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is-link">Go</button> </div> </div> </form> </div> </div> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Wong%2C+K&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Wong%2C+K&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Wong%2C+K&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Wong%2C+K&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2502.17116">arXiv:2502.17116</a> <span> [<a href="https://arxiv.org/pdf/2502.17116">pdf</a>, <a href="https://arxiv.org/format/2502.17116">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> A First Look at the Performance Enhancement Potential of Fluid Reconfigurable Intelligent Surface </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Salem%2C+A">Abdelhamid Salem</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Alexandropoulos%2C+G">George Alexandropoulos</a>, <a href="/search/eess?searchtype=author&query=Chae%2C+C">Chan-Byoung Chae</a>, <a href="/search/eess?searchtype=author&query=Murch%2C+R">Ross Murch</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2502.17116v1-abstract-short" style="display: inline;"> The fluid antenna concept represents shape-flexible and position-flexible antenna technologies designed to enhance wireless communication applications. In this paper, we apply this concept to reconfigurable intelligent surfaces (RISs), introducing fluid RIS (FRIS), where each tunably reflecting element becomes a fluid element with additional position reconfigurability. This new paradigm is referre… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.17116v1-abstract-full').style.display = 'inline'; document.getElementById('2502.17116v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.17116v1-abstract-full" style="display: none;"> The fluid antenna concept represents shape-flexible and position-flexible antenna technologies designed to enhance wireless communication applications. In this paper, we apply this concept to reconfigurable intelligent surfaces (RISs), introducing fluid RIS (FRIS), where each tunably reflecting element becomes a fluid element with additional position reconfigurability. This new paradigm is referred to as fluid RIS (FRIS). We investigate an FRIS-programmable wireless channel, where the fluid meta-surface is divided into non-overlapping subareas, each acting as a fluid element that can dynamically adjust both its position and phase shift of the reflected signal. We first analyze the single-user, single-input single-output (SU-SISO) channel, in which a single-antenna transmitter communicates with a single-antenna receiver via an FRIS. The achievable rate is maximized by optimizing the fluid elements using a particle swarm optimization (PSO)- based approach. Next, we extend our analysis to the multi-user, multiple-input single-output (MU-MISO) case, where a multi-antenna base station (BS) transmits individual data streams to multiple single-antenna users via an FRIS. In this case, the joint optimization of the positions and phase shifts of the FRIS element, as well as the BS precoding to maximize the sum-rate is studied. To solve the problem, a combination of techniques including PSO, semi-definite relaxation (SDR), and minimum mean square error (MMSE) is proposed. Numerical results demonstrate that the proposed FRIS approach significantly outperforms conventional RIS configurations in terms of achievable rate performance. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.17116v1-abstract-full').style.display = 'none'; document.getElementById('2502.17116v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2502.15258">arXiv:2502.15258</a> <span> [<a href="https://arxiv.org/pdf/2502.15258">pdf</a>, <a href="https://arxiv.org/format/2502.15258">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> On Performance of LoRa Fluid Antenna Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Mu%2C+G">Gaoze Mu</a>, <a href="/search/eess?searchtype=author&query=Hou%2C+Y">Yanzhao Hou</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Chen%2C+M">Mingjie Chen</a>, <a href="/search/eess?searchtype=author&query=Cui%2C+Q">Qimei Cui</a>, <a href="/search/eess?searchtype=author&query=Tao%2C+X">Xiaofeng Tao</a>, <a href="/search/eess?searchtype=author&query=Zhang%2C+P">Ping Zhang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2502.15258v1-abstract-short" style="display: inline;"> This paper advocates a fluid antenna system (FAS) assisting long-range communication (LoRa-FAS) for Internet-of-Things (IoT) applications. Our focus is on pilot sequence overhead and placement for FAS. Specifically, we consider embedding pilot sequences within symbols to reduce the equivalent symbol error rate (SER), leveraging the fact that the pilot sequences do not convey source information and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.15258v1-abstract-full').style.display = 'inline'; document.getElementById('2502.15258v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.15258v1-abstract-full" style="display: none;"> This paper advocates a fluid antenna system (FAS) assisting long-range communication (LoRa-FAS) for Internet-of-Things (IoT) applications. Our focus is on pilot sequence overhead and placement for FAS. Specifically, we consider embedding pilot sequences within symbols to reduce the equivalent symbol error rate (SER), leveraging the fact that the pilot sequences do not convey source information and correlation detection at the LoRa receiver needs not be performed across the entire symbol. We obtain closed-form approximations for the probability density function (PDF) and cumulative distribution function (CDF) of the FAS channel, assuming perfect channel state information (CSI). Moreover, the approximate SER, hence the bit error rate (BER), of the proposed LoRa-FAS is derived. Simulation results indicate that substantial SER gains can be achieved by FAS within the LoRa framework, even with a limited size of FAS. Furthermore, our analytical results align well with that of the Clarke's exact spatial correlation model. Finally, the correlation factor for the block correlation model should be selected as the proportion of the exact correlation matrix's eigenvalues greater than $1$. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.15258v1-abstract-full').style.display = 'none'; document.getElementById('2502.15258v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 7 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2502.04693">arXiv:2502.04693</a> <span> [<a href="https://arxiv.org/pdf/2502.04693">pdf</a>, <a href="https://arxiv.org/format/2502.04693">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Systems and Control">eess.SY</span> </div> </div> <p class="title is-5 mathjax"> Be Water, My Antennas: Riding on Radio Wave Fluctuation in Nature for Spatial Multiplexing using Programmable Meta-Fluid Antenna </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Liu%2C+B">Baiyang Liu</a>, <a href="/search/eess?searchtype=author&query=Tong%2C+K">Kin-Fai Tong</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Chae%2C+C">Chan-Byoung Chae</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+H">Hang Wong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2502.04693v1-abstract-short" style="display: inline;"> Interference and scattering, often deemed undesirable, are inevitable in wireless communications, especially when the current mobile networks and upcoming sixth generation (6G) have turned into ultra-dense networks. Current approaches relying on multiple-input multiple-output (MIMO) combined with artificial-intelligence-aided (AI) signal processing have drawbacks of being power-hungry and requirin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.04693v1-abstract-full').style.display = 'inline'; document.getElementById('2502.04693v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.04693v1-abstract-full" style="display: none;"> Interference and scattering, often deemed undesirable, are inevitable in wireless communications, especially when the current mobile networks and upcoming sixth generation (6G) have turned into ultra-dense networks. Current approaches relying on multiple-input multiple-output (MIMO) combined with artificial-intelligence-aided (AI) signal processing have drawbacks of being power-hungry and requiring wide bandwidth that raise scalability concerns. In this article, we take a radical approach and utilize the channel fading phenomenon to our advantage. Specifically, we propose a novel meta-fluid antenna architecture, referred to as the `fluid' antenna system (FAS), that can freely surf on radio wave fluctuations, like `fluid' figuratively speaking, with fine resolution in space to opportunistically avoid interference, eliminating the need for expensive signal processing. Our experimental results demonstrate that under rich scattering conditions, the proposed meta-fluidic architecture is able to exploit the natural ups and downs of radio waves in space for spatial multiplexing. These breakthrough results show that scattering can be desirable not harmful and interference can be dodged not suppressed, fundamentally changing our perception of fading and our understanding on how interference should be managed in wireless communications networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.04693v1-abstract-full').style.display = 'none'; document.getElementById('2502.04693v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2502.03922">arXiv:2502.03922</a> <span> [<a href="https://arxiv.org/pdf/2502.03922">pdf</a>, <a href="https://arxiv.org/format/2502.03922">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Graph Neural Network Enabled Fluid Antenna Systems: A Two-Stage Approach </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=He%2C+C">Changpeng He</a>, <a href="/search/eess?searchtype=author&query=Lu%2C+Y">Yang Lu</a>, <a href="/search/eess?searchtype=author&query=Chen%2C+W">Wei Chen</a>, <a href="/search/eess?searchtype=author&query=Ai%2C+B">Bo Ai</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Niyato%2C+D">Dusit Niyato</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2502.03922v1-abstract-short" style="display: inline;"> An emerging fluid antenna system (FAS) brings a new dimension, i.e., the antenna positions, to deal with the deep fading, but simultaneously introduces challenges related to the transmit design. This paper proposes an ``unsupervised learning to optimize" paradigm to optimize the FAS. Particularly, we formulate the sum-rate and energy efficiency (EE) maximization problems for a multiple-user multip… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.03922v1-abstract-full').style.display = 'inline'; document.getElementById('2502.03922v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.03922v1-abstract-full" style="display: none;"> An emerging fluid antenna system (FAS) brings a new dimension, i.e., the antenna positions, to deal with the deep fading, but simultaneously introduces challenges related to the transmit design. This paper proposes an ``unsupervised learning to optimize" paradigm to optimize the FAS. Particularly, we formulate the sum-rate and energy efficiency (EE) maximization problems for a multiple-user multiple-input single-output (MU-MISO) FAS and solved by a two-stage graph neural network (GNN) where the first stage and the second stage are for the inference of antenna positions and beamforming vectors, respectively. The outputs of the two stages are jointly input into a unsupervised loss function to train the two-stage GNN. The numerical results demonstrates that the advantages of the FAS for performance improvement and the two-stage GNN for real-time and scalable optimization. Besides, the two stages can function separately. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.03922v1-abstract-full').style.display = 'none'; document.getElementById('2502.03922v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2501.09106">arXiv:2501.09106</a> <span> [<a href="https://arxiv.org/pdf/2501.09106">pdf</a>, <a href="https://arxiv.org/format/2501.09106">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Physical Layer Security in FAS-aided Wireless Powered NOMA Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Ghadi%2C+F+R">Farshad Rostami Ghadi</a>, <a href="/search/eess?searchtype=author&query=Kaveh%2C+M">Masoud Kaveh</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Martin%2C+D">Diego Martin</a>, <a href="/search/eess?searchtype=author&query=Jantti%2C+R">Riku Jantti</a>, <a href="/search/eess?searchtype=author&query=Yan%2C+Z">Zheng Yan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2501.09106v1-abstract-short" style="display: inline;"> The rapid evolution of communication technologies and the emergence of sixth-generation (6G) networks have introduced unprecedented opportunities for ultra-reliable, low-latency, and energy-efficient communication. However, the integration of advanced technologies like non-orthogonal multiple access (NOMA) and wireless powered communication networks (WPCNs) brings significant challenges, particula… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.09106v1-abstract-full').style.display = 'inline'; document.getElementById('2501.09106v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.09106v1-abstract-full" style="display: none;"> The rapid evolution of communication technologies and the emergence of sixth-generation (6G) networks have introduced unprecedented opportunities for ultra-reliable, low-latency, and energy-efficient communication. However, the integration of advanced technologies like non-orthogonal multiple access (NOMA) and wireless powered communication networks (WPCNs) brings significant challenges, particularly in terms of energy constraints and security vulnerabilities. Traditional antenna systems and orthogonal multiple access schemes struggle to meet the increasing demands for performance and security in such environments. To address this gap, this paper investigates the impact of emerging fluid antenna systems (FAS) on the performance of physical layer security (PLS) in WPCNs. Specifically, we consider a scenario in which a transmitter, powered by a power beacon via an energy link, transmits confidential messages to legitimate FAS-aided users over information links while an external eavesdropper attempts to decode the transmitted signals. Additionally, users leverage the NOMA scheme, where the far user may also act as an internal eavesdropper. For the proposed model, we first derive the distributions of the equivalent channels at each node and subsequently obtain compact expressions for the secrecy outage probability (SOP) and average secrecy capacity (ASC), using the Gaussian quadrature methods. Our results reveal that incorporating the FAS for NOMA users, instead of the TAS, enhances the performance of the proposed secure WPCN. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.09106v1-abstract-full').style.display = 'none'; document.getElementById('2501.09106v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2025. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2501.06974">arXiv:2501.06974</a> <span> [<a href="https://arxiv.org/pdf/2501.06974">pdf</a>, <a href="https://arxiv.org/ps/2501.06974">ps</a>, <a href="https://arxiv.org/format/2501.06974">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Downlink OFDM-FAMA in 5G-NR Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Hong%2C+H">Hanjiang Hong</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Xu%2C+H">Hao Xu</a>, <a href="/search/eess?searchtype=author&query=Xu%2C+Y">Yin Xu</a>, <a href="/search/eess?searchtype=author&query=Shin%2C+H">Hyundong Shin</a>, <a href="/search/eess?searchtype=author&query=Murch%2C+R">Ross Murch</a>, <a href="/search/eess?searchtype=author&query=He%2C+D">Dazhi He</a>, <a href="/search/eess?searchtype=author&query=Zhang%2C+W">Wenjun Zhang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2501.06974v1-abstract-short" style="display: inline;"> Fluid antenna multiple access (FAMA), enabled by the fluid antenna system (FAS), offers a new and straightforward solution to massive connectivity. Previous results on FAMA were primarily based on narrowband channels. This paper studies the adoption of FAMA within the fifth-generation (5G) orthogonal frequency division multiplexing (OFDM) framework, referred to as OFDM-FAMA, and evaluate its perfo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.06974v1-abstract-full').style.display = 'inline'; document.getElementById('2501.06974v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.06974v1-abstract-full" style="display: none;"> Fluid antenna multiple access (FAMA), enabled by the fluid antenna system (FAS), offers a new and straightforward solution to massive connectivity. Previous results on FAMA were primarily based on narrowband channels. This paper studies the adoption of FAMA within the fifth-generation (5G) orthogonal frequency division multiplexing (OFDM) framework, referred to as OFDM-FAMA, and evaluate its performance in broadband multipath channels. We first design the OFDM-FAMA system, taking into account 5G channel coding and OFDM modulation. Then the system's achievable rate is analyzed, and an algorithm to approximate the FAS configuration at each user is proposed based on the rate. Extensive link-level simulation results reveal that OFDM-FAMA can significantly improve the multiplexing gain over the OFDM system with fixed-position antenna (FPA) users, especially when robust channel coding is applied and the number of radio-frequency (RF) chains at each user is small. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.06974v1-abstract-full').style.display = 'none'; document.getElementById('2501.06974v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2025. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted, under review</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2501.02911">arXiv:2501.02911</a> <span> [<a href="https://arxiv.org/pdf/2501.02911">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Fluid Antennas: Reshaping Intrinsic Properties for Flexible Radiation Characteristics in Intelligent Wireless Networks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Lu%2C+W">Wen-Jun Lu</a>, <a href="/search/eess?searchtype=author&query=He%2C+C">Chun-Xing He</a>, <a href="/search/eess?searchtype=author&query=Zhu%2C+Y">Yongxu Zhu</a>, <a href="/search/eess?searchtype=author&query=Tong%2C+K">Kin-Fai Tong</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Shin%2C+H">Hyundong Shin</a>, <a href="/search/eess?searchtype=author&query=Cui%2C+T+J">Tie Jun Cui</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2501.02911v1-abstract-short" style="display: inline;"> Fluid antennas present a relatively new idea for harnessing the fading and interference issues in multiple user wireless systems, such as 6G. Here, we systematically compare their unique radiation beam forming mechanism to the existing multiple-antenna systems in a wireless system. Subsequently, a unified mathematical model for fluid antennas is deduced based on the eigenmode theory. As mathematic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.02911v1-abstract-full').style.display = 'inline'; document.getElementById('2501.02911v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.02911v1-abstract-full" style="display: none;"> Fluid antennas present a relatively new idea for harnessing the fading and interference issues in multiple user wireless systems, such as 6G. Here, we systematically compare their unique radiation beam forming mechanism to the existing multiple-antenna systems in a wireless system. Subsequently, a unified mathematical model for fluid antennas is deduced based on the eigenmode theory. As mathematically derived from the multimode resonant theory, the spectral expansion model of any antennas which occupy variable spaces and have changeable feeding schemes can be generalized as fluid antennas. Non-liquid and liquid fluid antenna examples are presented, simulated and discussed. The symmetry or modal parity of eigenmodes is explored as an additional degree of freedom to design the fluid antennas for future wireless systems. As conceptually deduced and illustrated, the multi-dimensional and continuously adaptive ability of eigenmodes can be considered as the most fundamental intrinsic characteristic of the fluid antenna systems. It opens an uncharted area in the developments of intelligent antennas (IAs), which brings more flexibility to on-demand antenna beam null manipulating techniques for future wireless applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.02911v1-abstract-full').style.display = 'none'; document.getElementById('2501.02911v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2025. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2412.20418">arXiv:2412.20418</a> <span> [<a href="https://arxiv.org/pdf/2412.20418">pdf</a>, <a href="https://arxiv.org/format/2412.20418">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Image and Video Processing">eess.IV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> </div> </div> <p class="title is-5 mathjax"> Diff4MMLiTS: Advanced Multimodal Liver Tumor Segmentation via Diffusion-Based Image Synthesis and Alignment </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Chen%2C+S">Shiyun Chen</a>, <a href="/search/eess?searchtype=author&query=Lin%2C+L">Li Lin</a>, <a href="/search/eess?searchtype=author&query=Cheng%2C+P">Pujin Cheng</a>, <a href="/search/eess?searchtype=author&query=Jin%2C+Z">ZhiCheng Jin</a>, <a href="/search/eess?searchtype=author&query=Chen%2C+J">JianJian Chen</a>, <a href="/search/eess?searchtype=author&query=Zhu%2C+H">HaiDong Zhu</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K+K+Y">Kenneth K. Y. Wong</a>, <a href="/search/eess?searchtype=author&query=Tang%2C+X">Xiaoying Tang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2412.20418v1-abstract-short" style="display: inline;"> Multimodal learning has been demonstrated to enhance performance across various clinical tasks, owing to the diverse perspectives offered by different modalities of data. However, existing multimodal segmentation methods rely on well-registered multimodal data, which is unrealistic for real-world clinical images, particularly for indistinct and diffuse regions such as liver tumors. In this paper,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.20418v1-abstract-full').style.display = 'inline'; document.getElementById('2412.20418v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.20418v1-abstract-full" style="display: none;"> Multimodal learning has been demonstrated to enhance performance across various clinical tasks, owing to the diverse perspectives offered by different modalities of data. However, existing multimodal segmentation methods rely on well-registered multimodal data, which is unrealistic for real-world clinical images, particularly for indistinct and diffuse regions such as liver tumors. In this paper, we introduce Diff4MMLiTS, a four-stage multimodal liver tumor segmentation pipeline: pre-registration of the target organs in multimodal CTs; dilation of the annotated modality's mask and followed by its use in inpainting to obtain multimodal normal CTs without tumors; synthesis of strictly aligned multimodal CTs with tumors using the latent diffusion model based on multimodal CT features and randomly generated tumor masks; and finally, training the segmentation model, thus eliminating the need for strictly aligned multimodal data. Extensive experiments on public and internal datasets demonstrate the superiority of Diff4MMLiTS over other state-of-the-art multimodal segmentation methods. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.20418v1-abstract-full').style.display = 'none'; document.getElementById('2412.20418v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2412.04877">arXiv:2412.04877</a> <span> [<a href="https://arxiv.org/pdf/2412.04877">pdf</a>, <a href="https://arxiv.org/format/2412.04877">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Fluid Antenna Index Modulation for MIMO Systems: Robust Transmission and Low-Complexity Detection </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Guo%2C+X">Xinghao Guo</a>, <a href="/search/eess?searchtype=author&query=Xu%2C+Y">Yin Xu</a>, <a href="/search/eess?searchtype=author&query=He%2C+D">Dazhi He</a>, <a href="/search/eess?searchtype=author&query=Zhang%2C+C">Cixiao Zhang</a>, <a href="/search/eess?searchtype=author&query=Hong%2C+H">Hanjiang Hong</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Zhang%2C+W">Wenjun Zhang</a>, <a href="/search/eess?searchtype=author&query=Wu%2C+Y">Yiyan Wu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2412.04877v2-abstract-short" style="display: inline;"> The fluid antenna (FA) index modulation (IM)-enabled multiple-input multiple-output (MIMO) system, referred to as FA-IM, significantly enhances spectral efficiency (SE) compared to the conventional FA-assisted MIMO system. To improve robustness against the high spatial correlation among multiple activated ports of the fluid antenna, this paper proposes an innovative FA grouping-based IM (FAG-IM) s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.04877v2-abstract-full').style.display = 'inline'; document.getElementById('2412.04877v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.04877v2-abstract-full" style="display: none;"> The fluid antenna (FA) index modulation (IM)-enabled multiple-input multiple-output (MIMO) system, referred to as FA-IM, significantly enhances spectral efficiency (SE) compared to the conventional FA-assisted MIMO system. To improve robustness against the high spatial correlation among multiple activated ports of the fluid antenna, this paper proposes an innovative FA grouping-based IM (FAG-IM) system. A block grouping scheme is employed based on the spatial correlation model and the distribution structure of the ports. Then, a closed-form expression for the average bit error probability (ABEP) upper bound of the FAG-IM system is derived. To reduce the complexity of the receiver, the message passing architecture is incorporated into the FAG-IM system. Building on this, an efficient approximate message passing (AMP) detector, named structured AMP (S-AMP) detector, is proposed by exploiting the structural characteristics of the transmitted signals. Simulation results confirm that the proposed FAG-IM system significantly outperforms the existing FA-IM system in the presence of spatial correlation, achieving more robust transmission. Furthermore, it is demonstrated that the proposed low-complexity S-AMP detector not only reduces time complexity to a linear scale but also substantially improves bit error rate (BER) performance compared to the minimum mean square error (MMSE) detector, thereby enhancing the practical feasibility of the FAG-IM system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.04877v2-abstract-full').style.display = 'none'; document.getElementById('2412.04877v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to an IEEE journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2412.03839">arXiv:2412.03839</a> <span> [<a href="https://arxiv.org/pdf/2412.03839">pdf</a>, <a href="https://arxiv.org/format/2412.03839">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Fluid Antenna Systems Enabling 6G:Principles, Applications, and Research Directions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Wu%2C+T">Tuo Wu</a>, <a href="/search/eess?searchtype=author&query=Zhi%2C+K">Kangda Zhi</a>, <a href="/search/eess?searchtype=author&query=Yao%2C+J">Junteng Yao</a>, <a href="/search/eess?searchtype=author&query=Lai%2C+X">Xiazhi Lai</a>, <a href="/search/eess?searchtype=author&query=Zheng%2C+J">Jianchao Zheng</a>, <a href="/search/eess?searchtype=author&query=Niu%2C+H">Hong Niu</a>, <a href="/search/eess?searchtype=author&query=Elkashlan%2C+M">Maged Elkashlan</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Chae%2C+C">Chan-Byoung Chae</a>, <a href="/search/eess?searchtype=author&query=Ding%2C+Z">Zhiguo Ding</a>, <a href="/search/eess?searchtype=author&query=Karagiannidis%2C+G+K">George K. Karagiannidis</a>, <a href="/search/eess?searchtype=author&query=Debbah%2C+M">Merouane Debbah</a>, <a href="/search/eess?searchtype=author&query=Yuen%2C+C">Chau Yuen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2412.03839v1-abstract-short" style="display: inline;"> Fluid antenna system (FAS) as a new version of reconfigurable antenna technologies promoting shape and position flexibility, has emerged as an exciting and possibly transformative technology for wireless communications systems. FAS represents any software-controlled fluidic, conductive or dielectric structure that can dynamically alter antenna's shape and position to change the gain, the radiation… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.03839v1-abstract-full').style.display = 'inline'; document.getElementById('2412.03839v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.03839v1-abstract-full" style="display: none;"> Fluid antenna system (FAS) as a new version of reconfigurable antenna technologies promoting shape and position flexibility, has emerged as an exciting and possibly transformative technology for wireless communications systems. FAS represents any software-controlled fluidic, conductive or dielectric structure that can dynamically alter antenna's shape and position to change the gain, the radiation pattern, the operating frequency, and other critical radiation characteristics. With its capability, it is highly anticipated that FAS can contribute greatly to the upcoming sixth generation (6G) wireless networks. This article substantiates this thought by addressing four major questions: 1) Is FAS crucial to 6G? 2) How to characterize FAS? 3) What are the applications of FAS? 4) What are the relevant challenges and future research directions? In particular, five promising research directions that underscore the potential of FAS are discussed. We conclude this article by showcasing the impressive performance of FAS. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.03839v1-abstract-full').style.display = 'none'; document.getElementById('2412.03839v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.11453">arXiv:2411.11453</a> <span> [<a href="https://arxiv.org/pdf/2411.11453">pdf</a>, <a href="https://arxiv.org/ps/2411.11453">ps</a>, <a href="https://arxiv.org/format/2411.11453">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Fluid Antenna-Aided Rate-Splitting Multiple Access </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Ghadi%2C+F+R">Farshad Rostami Ghadi</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Lopez-Martinez%2C+F+J">F. Javier Lopez-Martinez</a>, <a href="/search/eess?searchtype=author&query=Hanzo%2C+L">Lajos Hanzo</a>, <a href="/search/eess?searchtype=author&query=Chae%2C+C">Chan-Byoung Chae</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2411.11453v1-abstract-short" style="display: inline;"> This letter considers a fluid antenna system (FAS)-aided rate-splitting multiple access (RSMA) approach for downlink transmission. In particular, a base station (BS) equipped with a single traditional antenna system (TAS) uses RSMA signaling to send information to several mobile users (MUs) each equipped with FAS. To understand the achievable performance, we first present the distribution of the e… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.11453v1-abstract-full').style.display = 'inline'; document.getElementById('2411.11453v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.11453v1-abstract-full" style="display: none;"> This letter considers a fluid antenna system (FAS)-aided rate-splitting multiple access (RSMA) approach for downlink transmission. In particular, a base station (BS) equipped with a single traditional antenna system (TAS) uses RSMA signaling to send information to several mobile users (MUs) each equipped with FAS. To understand the achievable performance, we first present the distribution of the equivalent channel gain based on the joint multivariate t-distribution and then derive a compact analytical expression for the outage probability (OP). Moreover, we obtain the asymptotic OP in the high signal-to-noise ratio (SNR) regime. Numerical results show that combining FAS with RSMA significantly outperforms TAS and conventional multiple access schemes, such as non-orthogonal multiple access (NOMA), in terms of OP. The results also indicate that FAS can be the tool that greatly improves the practicality of RSMA. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.11453v1-abstract-full').style.display = 'none'; document.getElementById('2411.11453v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.09235">arXiv:2411.09235</a> <span> [<a href="https://arxiv.org/pdf/2411.09235">pdf</a>, <a href="https://arxiv.org/ps/2411.09235">ps</a>, <a href="https://arxiv.org/format/2411.09235">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> FAS for Secure and Covert Communications </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Yao%2C+J">Junteng Yao</a>, <a href="/search/eess?searchtype=author&query=Xin%2C+L">Liangxiao Xin</a>, <a href="/search/eess?searchtype=author&query=Wu%2C+T">Tuo Wu</a>, <a href="/search/eess?searchtype=author&query=Jin%2C+M">Ming Jin</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Yuen%2C+C">Chau Yuen</a>, <a href="/search/eess?searchtype=author&query=Shin%2C+H">Hyundong Shin</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2411.09235v1-abstract-short" style="display: inline;"> This letter considers a fluid antenna system (FAS)-aided secure and covert communication system, where the transmitter adjusts multiple fluid antennas' positions to achieve secure and covert transmission under the threat of an eavesdropper and the detection of a warden. This letter aims to maximize the secrecy rate while satisfying the covertness constraint. Unfortunately, the optimization problem… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.09235v1-abstract-full').style.display = 'inline'; document.getElementById('2411.09235v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.09235v1-abstract-full" style="display: none;"> This letter considers a fluid antenna system (FAS)-aided secure and covert communication system, where the transmitter adjusts multiple fluid antennas' positions to achieve secure and covert transmission under the threat of an eavesdropper and the detection of a warden. This letter aims to maximize the secrecy rate while satisfying the covertness constraint. Unfortunately, the optimization problem is non-convex due to the coupled variables. To tackle this, we propose an alternating optimization (AO) algorithm to alternatively optimize the optimization variables in an iterative manner. In particular, we use a penalty-based method and the majorization-minimization (MM) algorithm to optimize the transmit beamforming and fluid antennas' positions, respectively. Simulation results show that FAS can significantly improve the performance of secrecy and covertness compared to the fixed-position antenna (FPA)-based schemes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.09235v1-abstract-full').style.display = 'none'; document.getElementById('2411.09235v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.08386">arXiv:2411.08386</a> <span> [<a href="https://arxiv.org/pdf/2411.08386">pdf</a>, <a href="https://arxiv.org/ps/2411.08386">ps</a>, <a href="https://arxiv.org/format/2411.08386">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> A Secure Beamforming Design: When Fluid Antenna Meets NOMA </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Mai%2C+L">Lifeng Mai</a>, <a href="/search/eess?searchtype=author&query=Yao%2C+J">Junteng Yao</a>, <a href="/search/eess?searchtype=author&query=Tang%2C+J">Jie Tang</a>, <a href="/search/eess?searchtype=author&query=Wu%2C+T">Tuo Wu</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Shin%2C+H">Hyundong Shin</a>, <a href="/search/eess?searchtype=author&query=Adachi%2C+F">Fumiyuki Adachi</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2411.08386v1-abstract-short" style="display: inline;"> This letter proposes a secure beamforming design for downlink non-orthogonal multiple access (NOMA) systems utilizing fluid antenna systems (FAS). We consider a setup where a base station (BS) with $M$ fluid antennas (FAs) communicates to a cell-center user (CU) and a cell-edge user (CEU), each with a FA. The CU is the intended recipient while the CEU is regarded as a potential eavesdropper. Our a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.08386v1-abstract-full').style.display = 'inline'; document.getElementById('2411.08386v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.08386v1-abstract-full" style="display: none;"> This letter proposes a secure beamforming design for downlink non-orthogonal multiple access (NOMA) systems utilizing fluid antenna systems (FAS). We consider a setup where a base station (BS) with $M$ fluid antennas (FAs) communicates to a cell-center user (CU) and a cell-edge user (CEU), each with a FA. The CU is the intended recipient while the CEU is regarded as a potential eavesdropper. Our aim is to maximize the achievable secrecy rate by jointly optimizing the secure beamforming vectors and the positions of FAs. To tackle this, we adopt an alternating optimization (AO) algorithm that optimizes secure beamforming and the positions of the FAs iteratively while keeping the other variables fixed. Numerical results illustrate that when FAs meet NOMA, the proposed scheme greatly enhances the secrecy rate compared to conventional multiple-input single-output (MISO) fixed antenna NOMA systems and other benchmark schemes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.08386v1-abstract-full').style.display = 'none'; document.getElementById('2411.08386v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.08383">arXiv:2411.08383</a> <span> [<a href="https://arxiv.org/pdf/2411.08383">pdf</a>, <a href="https://arxiv.org/format/2411.08383">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> FAS-Driven Spectrum Sensing for Cognitive Radio Networks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Yao%2C+J">Junteng Yao</a>, <a href="/search/eess?searchtype=author&query=Jin%2C+M">Ming Jin</a>, <a href="/search/eess?searchtype=author&query=Wu%2C+T">Tuo Wu</a>, <a href="/search/eess?searchtype=author&query=Elkashlan%2C+M">Maged Elkashlan</a>, <a href="/search/eess?searchtype=author&query=Yuen%2C+C">Chau Yuen</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Karagiannidis%2C+G+K">George K. Karagiannidis</a>, <a href="/search/eess?searchtype=author&query=Shin%2C+H">Hyundong Shin</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2411.08383v1-abstract-short" style="display: inline;"> Cognitive radio (CR) networks face significant challenges in spectrum sensing, especially under spectrum scarcity. Fluid antenna systems (FAS) can offer an unorthodox solution due to their ability to dynamically adjust antenna positions for improved channel gain. In this letter, we study a FAS-driven CR setup where a secondary user (SU) adjusts the positions of fluid antennas to detect signals fro… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.08383v1-abstract-full').style.display = 'inline'; document.getElementById('2411.08383v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.08383v1-abstract-full" style="display: none;"> Cognitive radio (CR) networks face significant challenges in spectrum sensing, especially under spectrum scarcity. Fluid antenna systems (FAS) can offer an unorthodox solution due to their ability to dynamically adjust antenna positions for improved channel gain. In this letter, we study a FAS-driven CR setup where a secondary user (SU) adjusts the positions of fluid antennas to detect signals from the primary user (PU). We aim to maximize the detection probability under the constraints of the false alarm probability and the received beamforming of the SU. To address this problem, we first derive a closed-form expression for the optimal detection threshold and reformulate the problem to find its solution. Then an alternating optimization (AO) scheme is proposed to decompose the problem into several sub-problems, addressing both the received beamforming and the antenna positions at the SU. The beamforming subproblem is addressed using a closed-form solution, while the fluid antenna positions are solved by successive convex approximation (SCA). Simulation results reveal that the proposed algorithm provides significant improvements over traditional fixed-position antenna (FPA) schemes in terms of spectrum sensing performance. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.08383v1-abstract-full').style.display = 'none'; document.getElementById('2411.08383v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.06642">arXiv:2411.06642</a> <span> [<a href="https://arxiv.org/pdf/2411.06642">pdf</a>, <a href="https://arxiv.org/ps/2411.06642">ps</a>, <a href="https://arxiv.org/format/2411.06642">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> </div> </div> <p class="title is-5 mathjax"> Antenna Coding Empowered by Pixel Antennas </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Shen%2C+S">Shanpu Shen</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Murch%2C+R">Ross Murch</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2411.06642v1-abstract-short" style="display: inline;"> Pixel antennas, based on discretizing a continuous radiation surface into small elements called pixels, are a flexible reconfigurable antenna technology. By controlling the connections between pixels via switches, the characteristics of pixel antennas can be adjusted to enhance the wireless channel. Inspired by this, we propose a novel technique denoted antenna coding empowered by pixel antennas.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.06642v1-abstract-full').style.display = 'inline'; document.getElementById('2411.06642v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.06642v1-abstract-full" style="display: none;"> Pixel antennas, based on discretizing a continuous radiation surface into small elements called pixels, are a flexible reconfigurable antenna technology. By controlling the connections between pixels via switches, the characteristics of pixel antennas can be adjusted to enhance the wireless channel. Inspired by this, we propose a novel technique denoted antenna coding empowered by pixel antennas. We first derive a physical and electromagnetic based communication model for pixel antennas using microwave multiport network theory and beamspace channel representation. With the model, we optimize the antenna coding to maximize the channel gain in a single-input single-output (SISO) pixel antenna system and develop a codebook design for antenna coding to reduce the computational complexity. We analyze the average channel gain of SISO pixel antenna system and derive the corresponding upper bound. In addition, we jointly optimize the antenna coding and transmit signal covariance matrix to maximize the channel capacity in a multiple-input multiple-output (MIMO) pixel antenna system. Simulation results show that using pixel antennas can enhance the average channel gain by up to 5.4 times and channel capacity by up to 3.1 times, demonstrating the significant potential of pixel antennas as a new dimension to design and optimize wireless communication systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.06642v1-abstract-full').style.display = 'none'; document.getElementById('2411.06642v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 11 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.14088">arXiv:2409.14088</a> <span> [<a href="https://arxiv.org/pdf/2409.14088">pdf</a>, <a href="https://arxiv.org/ps/2409.14088">ps</a>, <a href="https://arxiv.org/format/2409.14088">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Intelligent Reflecting Surface-Aided Multiuser Communication: Co-design of Transmit Diversity and Active/Passive Precoding </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Zheng%2C+B">Beixiong Zheng</a>, <a href="/search/eess?searchtype=author&query=Ma%2C+T">Tiantian Ma</a>, <a href="/search/eess?searchtype=author&query=Tang%2C+J">Jie Tang</a>, <a href="/search/eess?searchtype=author&query=You%2C+C">Changsheng You</a>, <a href="/search/eess?searchtype=author&query=Lin%2C+S">Shaoe Lin</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.14088v1-abstract-short" style="display: inline;"> Intelligent reflecting surface (IRS) has become a cost-effective solution for constructing a smart and adaptive radio environment. Most previous works on IRS have jointly designed the active and passive precoding based on perfectly or partially known channel state information (CSI). However, in delay-sensitive or high-mobility communications, it is imperative to explore more effective methods for… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.14088v1-abstract-full').style.display = 'inline'; document.getElementById('2409.14088v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.14088v1-abstract-full" style="display: none;"> Intelligent reflecting surface (IRS) has become a cost-effective solution for constructing a smart and adaptive radio environment. Most previous works on IRS have jointly designed the active and passive precoding based on perfectly or partially known channel state information (CSI). However, in delay-sensitive or high-mobility communications, it is imperative to explore more effective methods for leveraging IRS to enhance communication reliability without the need for any CSI. In this paper, we investigate an innovative IRS-aided multiuser communication system, which integrates an IRS with its aided multi-antenna base station (BS) to simultaneously serve multiple high-mobility users through transmit diversity and multiple low-mobility users through active/passive precoding. In specific, we first reveal that when dynamically tuning the IRS's common phase-shift shared with all reflecting elements, its passive precoding gain to any low-mobility user remains unchanged. Inspired by this property, we utilize the design of common phase-shift at the IRS for achieving transmit diversity to serve high-mobility users, yet without requiring any CSI at the BS. Meanwhile, the active/passive precoding design is incorporated into the IRS-integrated BS to serve low-mobility users (assuming the CSI is known). Then, taking into account the interference among different users, we formulate and solve a joint optimization problem of the IRS's reflect precoding and the BS's transmit precoding, with the aim of minimizing the total transmit power at the BS. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.14088v1-abstract-full').style.display = 'none'; document.getElementById('2409.14088v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 9 figures, Early Access in IEEE TWC</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.08525">arXiv:2409.08525</a> <span> [<a href="https://arxiv.org/pdf/2409.08525">pdf</a>, <a href="https://arxiv.org/ps/2409.08525">ps</a>, <a href="https://arxiv.org/format/2409.08525">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Frequency Diverse RIS (FD-RIS) Enhanced Wireless Communications via Joint Distance-Angle Beamforming </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Xiao%2C+H">Han Xiao</a>, <a href="/search/eess?searchtype=author&query=Hu%2C+X">Xiaoyan Hu</a>, <a href="/search/eess?searchtype=author&query=Wang%2C+W">Wenjie Wang</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Yang%2C+K">Kun Yang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.08525v1-abstract-short" style="display: inline;"> The conventional reconfigurable intelligent surface (RIS) assisted far-field communication systems can only implement angle beamforming, which actually limits the capability for reconfiguring the wireless propagation environment. To overcome this limitation, this paper proposes a newly designed frequency diverse RIS (FD-RIS), which can achieve joint distance-angle beamforming with the assistance o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.08525v1-abstract-full').style.display = 'inline'; document.getElementById('2409.08525v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.08525v1-abstract-full" style="display: none;"> The conventional reconfigurable intelligent surface (RIS) assisted far-field communication systems can only implement angle beamforming, which actually limits the capability for reconfiguring the wireless propagation environment. To overcome this limitation, this paper proposes a newly designed frequency diverse RIS (FD-RIS), which can achieve joint distance-angle beamforming with the assistance of the time modulation technology. The signal processing model for FD-RIS-aided wireless communications is first derived. Then, an optimization problem aimed at maximizing the achievable rate is formulated where the frequency-time modulations are jointly optimized to achieve distance-angle beamforming. Furthermore, a novel iterative algorithm based on the cross-entropy optimization (CEO) framework is proposed to effectively handle the non-convex optimization problem. The numerical results validate that the proposed FD-RIS assisted communication scheme can achieve a notable performance improvement compared with the baseline scheme utilizing traditional RIS. In addition, the effectiveness of the proposed CEO algorithm is further verified by comparing with the benchmark using the genetic algorithm (GA). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.08525v1-abstract-full').style.display = 'none'; document.getElementById('2409.08525v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.16251">arXiv:2408.16251</a> <span> [<a href="https://arxiv.org/pdf/2408.16251">pdf</a>, <a href="https://arxiv.org/format/2408.16251">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Neural Network-Assisted Hybrid Model Based Message Passing for Parametric Holographic MIMO Near Field Channel Estimation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Yuan%2C+Z">Zhengdao Yuan</a>, <a href="/search/eess?searchtype=author&query=Guo%2C+Y">Yabo Guo</a>, <a href="/search/eess?searchtype=author&query=Gao%2C+D">Dawei Gao</a>, <a href="/search/eess?searchtype=author&query=Guo%2C+Q">Qinghua Guo</a>, <a href="/search/eess?searchtype=author&query=Wang%2C+Z">Zhongyong Wang</a>, <a href="/search/eess?searchtype=author&query=Huang%2C+C">Chongwen Huang</a>, <a href="/search/eess?searchtype=author&query=Jin%2C+M">Ming Jin</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.16251v1-abstract-short" style="display: inline;"> Holographic multiple-input and multiple-output (HMIMO) is a promising technology with the potential to achieve high energy and spectral efficiencies, enhance system capacity and diversity, etc. In this work, we address the challenge of HMIMO near field (NF) channel estimation, which is complicated by the intricate model introduced by the dyadic Green's function. Despite its complexity, the channel… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.16251v1-abstract-full').style.display = 'inline'; document.getElementById('2408.16251v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.16251v1-abstract-full" style="display: none;"> Holographic multiple-input and multiple-output (HMIMO) is a promising technology with the potential to achieve high energy and spectral efficiencies, enhance system capacity and diversity, etc. In this work, we address the challenge of HMIMO near field (NF) channel estimation, which is complicated by the intricate model introduced by the dyadic Green's function. Despite its complexity, the channel model is governed by a limited set of parameters. This makes parametric channel estimation highly attractive, offering substantial performance enhancements and enabling the extraction of valuable sensing parameters, such as user locations, which are particularly beneficial in mobile networks. However, the relationship between these parameters and channel gains is nonlinear and compounded by integration, making the estimation a formidable task. To tackle this problem, we propose a novel neural network (NN) assisted hybrid method. With the assistance of NNs, we first develop a novel hybrid channel model with a significantly simplified expression compared to the original one, thereby enabling parametric channel estimation. Using the readily available training data derived from the original channel model, the NNs in the hybrid channel model can be effectively trained offline. Then, building upon this hybrid channel model, we formulate the parametric channel estimation problem with a probabilistic framework and design a factor graph representation for Bayesian estimation. Leveraging the factor graph representation and unitary approximate message passing (UAMP), we develop an effective message passing-based Bayesian channel estimation algorithm. Extensive simulations demonstrate the superior performance of the proposed method. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.16251v1-abstract-full').style.display = 'none'; document.getElementById('2408.16251v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.14969">arXiv:2408.14969</a> <span> [<a href="https://arxiv.org/pdf/2408.14969">pdf</a>, <a href="https://arxiv.org/format/2408.14969">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Secrecy Performance Analysis of RIS-Aided Fluid Antenna Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Ghadi%2C+F+R">Farshad Rostami Ghadi</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Kaveh%2C+M">Masoud Kaveh</a>, <a href="/search/eess?searchtype=author&query=Lopez-Martinez%2C+F+J">F. Javier Lopez-Martinez</a>, <a href="/search/eess?searchtype=author&query=New%2C+W+K">Wee Kiat New</a>, <a href="/search/eess?searchtype=author&query=Xu%2C+H">Hao Xu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.14969v1-abstract-short" style="display: inline;"> This paper examines the impact of emerging fluid antenna systems (FAS) on reconfigurable intelligent surface (RIS)-aided secure communications. Specifically, we consider a classic wiretap channel, where a fixed-antenna transmitter sends confidential information to an FAS-equipped legitimate user with the help of an RIS, while an FAS-equipped eavesdropper attempts to decode the message. To evaluate… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.14969v1-abstract-full').style.display = 'inline'; document.getElementById('2408.14969v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.14969v1-abstract-full" style="display: none;"> This paper examines the impact of emerging fluid antenna systems (FAS) on reconfigurable intelligent surface (RIS)-aided secure communications. Specifically, we consider a classic wiretap channel, where a fixed-antenna transmitter sends confidential information to an FAS-equipped legitimate user with the help of an RIS, while an FAS-equipped eavesdropper attempts to decode the message. To evaluate the proposed wireless scenario, we first introduce the cumulative distribution function (CDF) and probability density function (PDF) of the signal-to-noise ratio (SNR) at each node, using the central limit theorem and the Gaussian copula function. We then derive a compact analytical expression for the secrecy outage probability (SOP). Our numerical results reveal how the incorporation of FAS and RIS can significantly enhance the performance of secure communications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.14969v1-abstract-full').style.display = 'none'; document.getElementById('2408.14969v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.14947">arXiv:2408.14947</a> <span> [<a href="https://arxiv.org/pdf/2408.14947">pdf</a>, <a href="https://arxiv.org/format/2408.14947">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Image and Video Processing">eess.IV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> </div> </div> <p class="title is-5 mathjax"> ERX: A Fast Real-Time Anomaly Detection Algorithm for Hyperspectral Line Scanning </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Garske%2C+S">Samuel Garske</a>, <a href="/search/eess?searchtype=author&query=Evans%2C+B">Bradley Evans</a>, <a href="/search/eess?searchtype=author&query=Artlett%2C+C">Christopher Artlett</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">KC Wong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.14947v4-abstract-short" style="display: inline;"> Detecting unexpected objects (anomalies) in real time has great potential for monitoring, managing, and protecting the environment. Hyperspectral line-scan cameras are a low-cost solution that enhance confidence in anomaly detection over RGB and multispectral imagery. However, existing line-scan algorithms are too slow when using small computers (e.g. those onboard a drone or small satellite), do… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.14947v4-abstract-full').style.display = 'inline'; document.getElementById('2408.14947v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.14947v4-abstract-full" style="display: none;"> Detecting unexpected objects (anomalies) in real time has great potential for monitoring, managing, and protecting the environment. Hyperspectral line-scan cameras are a low-cost solution that enhance confidence in anomaly detection over RGB and multispectral imagery. However, existing line-scan algorithms are too slow when using small computers (e.g. those onboard a drone or small satellite), do not adapt to changing scenery, or lack robustness against geometric distortions. This paper introduces the Exponentially moving RX algorithm (ERX) to address these issues, and compares it with four existing RX-based anomaly detection methods for hyperspectral line scanning. Three large and more complex datasets are also introduced to better assess the practical challenges when using line-scan cameras (two hyperspectral and one multispectral). ERX was evaluated using a Jetson Xavier NX edge computing module (6-core CPU, 8GB RAM, 20W power draw), achieving the best combination of speed and detection performance. ERX was 9 times faster than the next-best algorithm on the dataset with the highest number of bands (108 band), with an average speed of 561 lines per second on the Jetson. It achieved a 29.3% AUC improvement over the next-best algorithm on the most challenging dataset, while showing greater adaptability through consistently high AUC scores regardless of the camera's starting location. ERX performed robustly across all datasets, achieving an AUC of 0.941 on a drone-collected hyperspectral line scan dataset without geometric corrections (a 16.9% improvement over existing algorithms). This work enables future research on the detection of anomalous objects in real time, adaptive and automatic threshold selection, and real-time field tests. The datasets and the Python code are openly available at: https://github.com/WiseGamgee/HyperAD, promoting accessibility and future work. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.14947v4-abstract-full').style.display = 'none'; document.getElementById('2408.14947v4-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">17 pages, 13 figures, 4 tables, code and datasets accessible at https://github.com/WiseGamgee/HyperAD</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.13447">arXiv:2408.13447</a> <span> [<a href="https://arxiv.org/pdf/2408.13447">pdf</a>, <a href="https://arxiv.org/ps/2408.13447">ps</a>, <a href="https://arxiv.org/format/2408.13447">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> FAS-RIS Communication: Model, Analysis, and Optimization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Yao%2C+J">Junteng Yao</a>, <a href="/search/eess?searchtype=author&query=Zheng%2C+J">Jianchao Zheng</a>, <a href="/search/eess?searchtype=author&query=Wu%2C+T">Tuo Wu</a>, <a href="/search/eess?searchtype=author&query=Jin%2C+M">Ming Jin</a>, <a href="/search/eess?searchtype=author&query=Yuen%2C+C">Chau Yuen</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Adachi%2C+F">Fumiyuki Adachi</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.13447v1-abstract-short" style="display: inline;"> This correspondence investigates the novel fluid antenna system (FAS) technology, combining with reconfigurable intelligent surface (RIS) for wireless communications, where a base station (BS) communicates with a FAS-enabled user with the assistance of a RIS. To analyze this technology, we derive the outage probability based on the block-diagonal matrix approximation (BDMA) model. With this, we ob… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.13447v1-abstract-full').style.display = 'inline'; document.getElementById('2408.13447v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.13447v1-abstract-full" style="display: none;"> This correspondence investigates the novel fluid antenna system (FAS) technology, combining with reconfigurable intelligent surface (RIS) for wireless communications, where a base station (BS) communicates with a FAS-enabled user with the assistance of a RIS. To analyze this technology, we derive the outage probability based on the block-diagonal matrix approximation (BDMA) model. With this, we obtain the upper bound, lower bound, and asymptotic approximation of the outage probability to gain more insights. Moreover, we design the phase shift matrix of the RIS in order to minimize the system outage probability. Simulation results confirm the accuracy of our approximations and that the proposed schemes outperform benchmarks significantly. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.13447v1-abstract-full').style.display = 'none'; document.getElementById('2408.13447v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.13444">arXiv:2408.13444</a> <span> [<a href="https://arxiv.org/pdf/2408.13444">pdf</a>, <a href="https://arxiv.org/ps/2408.13444">ps</a>, <a href="https://arxiv.org/format/2408.13444">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> FAS-RIS: A Block-Correlation Model Analysis </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Lai%2C+X">Xiazhi Lai</a>, <a href="/search/eess?searchtype=author&query=Yao%2C+J">Junteng Yao</a>, <a href="/search/eess?searchtype=author&query=Zhi%2C+K">Kangda Zhi</a>, <a href="/search/eess?searchtype=author&query=Wu%2C+T">Tuo Wu</a>, <a href="/search/eess?searchtype=author&query=Morales-Jimenez%2C+D">David Morales-Jimenez</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.13444v1-abstract-short" style="display: inline;"> In this correspondence, we analyze the performance of a reconfigurable intelligent surface (RIS)-aided communication system that involves a fluid antenna system (FAS)-enabled receiver. By applying the central limit theorem (CLT), we derive approximate expressions for the system outage probability when the RIS has a large number of elements. Also, we adopt the block-correlation channel model to sim… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.13444v1-abstract-full').style.display = 'inline'; document.getElementById('2408.13444v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.13444v1-abstract-full" style="display: none;"> In this correspondence, we analyze the performance of a reconfigurable intelligent surface (RIS)-aided communication system that involves a fluid antenna system (FAS)-enabled receiver. By applying the central limit theorem (CLT), we derive approximate expressions for the system outage probability when the RIS has a large number of elements. Also, we adopt the block-correlation channel model to simplify the outage probability expressions, reducing the computational complexity and shedding light on the impact of the number of ports. Numerical results validate the effectiveness of our analysis, especially in scenarios with a large number of RIS elements. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.13444v1-abstract-full').style.display = 'none'; document.getElementById('2408.13444v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.04724">arXiv:2408.04724</a> <span> [<a href="https://arxiv.org/pdf/2408.04724">pdf</a>, <a href="https://arxiv.org/format/2408.04724">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Performance Analysis of FAS-Aided NOMA-ISAC: A Backscattering Scenario </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Ghadi%2C+F+R">Farshad Rostami Ghadi</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Lopez-Martinez%2C+F+J">F. Javier Lopez-Martinez</a>, <a href="/search/eess?searchtype=author&query=Shin%2C+H">Hyundong Shin</a>, <a href="/search/eess?searchtype=author&query=Hanzo%2C+L">Lajos Hanzo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.04724v1-abstract-short" style="display: inline;"> This paper investigates a two-user downlink system for integrated sensing and communication (ISAC) in which the two users deploy a fluid antenna system (FAS) and adopt the nonorthogonal multiple access (NOMA) strategy. Specifically, the integrated sensing and backscatter communication (ISABC) model is considered, where a dual-functional base station (BS) serves to communicate the two users and sen… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.04724v1-abstract-full').style.display = 'inline'; document.getElementById('2408.04724v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.04724v1-abstract-full" style="display: none;"> This paper investigates a two-user downlink system for integrated sensing and communication (ISAC) in which the two users deploy a fluid antenna system (FAS) and adopt the nonorthogonal multiple access (NOMA) strategy. Specifically, the integrated sensing and backscatter communication (ISABC) model is considered, where a dual-functional base station (BS) serves to communicate the two users and sense a tag's surrounding. In contrast to conventional ISAC, the backscattering tag reflects the signals transmitted by the BS to the NOMA users and enhances their communication performance. Furthermore, the BS extracts environmental information from the same backscatter signal in the sensing stage. Firstly, we derive closed-form expressions for both the cumulative distribution function (CDF) and probability density function (PDF) of the equivalent channel at the users utilizing the moment matching method and the Gaussian copula. Then in the communication stage, we obtain closed-form expressions for both the outage probability and for the corresponding asymptotic expressions in the high signal-to-noise ratio (SNR) regime. Moreover, using numerical integration techniques such as the Gauss-Laguerre quadrature (GLQ), we have series-form expressions for the user ergodic communication rates (ECRs). In addition, we get a closed-form expression for the ergodic sensing rate (ESR) using the Cramer-Rao lower bound (CRLB). Finally, the accuracy of our analytical results is validated numerically, and we confirm the superiority of employing FAS over traditional fixed-position antenna systems in both ISAC and ISABC. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.04724v1-abstract-full').style.display = 'none'; document.getElementById('2408.04724v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.02160">arXiv:2408.02160</a> <span> [<a href="https://arxiv.org/pdf/2408.02160">pdf</a>, <a href="https://arxiv.org/ps/2408.02160">ps</a>, <a href="https://arxiv.org/format/2408.02160">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Modeling and Design of RIS-Assisted Multi-cell Multi-band Networks with RSMA </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Salem%2C+A">Abdelhamid Salem</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Chae%2C+C">Chan-Byoung Chae</a>, <a href="/search/eess?searchtype=author&query=Zhang%2C+Y">Yangyang Zhang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.02160v1-abstract-short" style="display: inline;"> Reconfigurable intelligent surface (RIS) has been identified as a promising technology for future wireless communication systems due to its ability to manipulate the propagation environment intelligently. RIS is a frequency-selective device, thus it can only effectively manipulate the propagation of signals within a specific frequency band. This frequency selective characteristic can make deployin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.02160v1-abstract-full').style.display = 'inline'; document.getElementById('2408.02160v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.02160v1-abstract-full" style="display: none;"> Reconfigurable intelligent surface (RIS) has been identified as a promising technology for future wireless communication systems due to its ability to manipulate the propagation environment intelligently. RIS is a frequency-selective device, thus it can only effectively manipulate the propagation of signals within a specific frequency band. This frequency selective characteristic can make deploying RIS in wireless cellular networks more challenging, as adjacent base stations (BSs) operate on different frequency bands. In addition, rate-splitting multiple access (RSMA) scheme has been shown to enhance the performance of RIS-aided multi-user communication systems. Accordingly, this work considers a more practical reflection model for RIS-aided RSMA communication systems, which accounts for the responses of signals across different frequency bands. To that end, new analytical expressions for the ergodic sum-rate are derived using the moment generating function (MGF) and Jensen inequality. Based on these analytical sum-rate expressions, novel practical RIS reflection designs and power allocation strategies for the RSMA scheme are proposed and investigated to maximize the achievable sum-rate in RIS-assisted multi-cell, multi-band cellular networks. Simple sub-optimal designs are also introduced and discussed. The results validate the significant gains of our proposed reflection design algorithms with RSMA over conventional schemes in terms of achievable sum-rate. Additionally, the power allocation strategy for the RSMA scheme is shown to offer superior performance compared to conventional precoding schemes that do not rely on RSMA. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.02160v1-abstract-full').style.display = 'none'; document.getElementById('2408.02160v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.11389">arXiv:2407.11389</a> <span> [<a href="https://arxiv.org/pdf/2407.11389">pdf</a>, <a href="https://arxiv.org/ps/2407.11389">ps</a>, <a href="https://arxiv.org/format/2407.11389">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Networking and Internet Architecture">cs.NI</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Spatial-spectral Cell-free Networks: A Large-scale Case Study </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Zhu%2C+Z">Zesheng Zhu</a>, <a href="/search/eess?searchtype=author&query=Wang%2C+L">Lifeng Wang</a>, <a href="/search/eess?searchtype=author&query=Wang%2C+X">Xin Wang</a>, <a href="/search/eess?searchtype=author&query=Wang%2C+D">Dongming Wang</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.11389v1-abstract-short" style="display: inline;"> This paper studies the large-scale cell-free networks where dense distributed access points (APs) serve many users. As a promising next-generation network architecture, cell-free networks enable ultra-reliable connections and minimal fading/blockage, which are much favorable to the millimeter wave and Terahertz transmissions. However, conventional beam management with large phased arrays in a cell… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.11389v1-abstract-full').style.display = 'inline'; document.getElementById('2407.11389v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.11389v1-abstract-full" style="display: none;"> This paper studies the large-scale cell-free networks where dense distributed access points (APs) serve many users. As a promising next-generation network architecture, cell-free networks enable ultra-reliable connections and minimal fading/blockage, which are much favorable to the millimeter wave and Terahertz transmissions. However, conventional beam management with large phased arrays in a cell is very time-consuming in the higher-frequencies, and could be worsened when deploying a large number of coordinated APs in the cell-free systems. To tackle this challenge, the spatial-spectral cell-free networks with the leaky-wave antennas are established by coupling the propagation angles with frequencies. The beam training overhead in this direction can be significantly reduced through exploiting such spatial-spectral coupling effects. In the considered large-scale spatial-spectral cell-free networks, a novel subchannel allocation solution at sub-terahertz bands is proposed by leveraging the relationship between cross-entropy method and mixture model. Since initial access and AP clustering play a key role in achieving scalable large-scale cell-free networks, a hierarchical AP clustering solution is proposed to make the joint initial access and cluster formation, which is adaptive and has no need to initialize the number of AP clusters. After AP clustering, a subchannel allocation solution is devised to manage the interference between AP clusters. Numerical results are presented to confirm the efficiency of the proposed solutions and indicate that besides subchannel allocation, AP clustering can also have a big impact on the large-scale cell-free network performance at sub-terahertz bands. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.11389v1-abstract-full').style.display = 'none'; document.getElementById('2407.11389v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.08141">arXiv:2407.08141</a> <span> [<a href="https://arxiv.org/pdf/2407.08141">pdf</a>, <a href="https://arxiv.org/ps/2407.08141">ps</a>, <a href="https://arxiv.org/format/2407.08141">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> A Framework of FAS-RIS Systems: Performance Analysis and Throughput Optimization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Yao%2C+J">Junteng Yao</a>, <a href="/search/eess?searchtype=author&query=Lai%2C+X">Xiazhi Lai</a>, <a href="/search/eess?searchtype=author&query=Zhi%2C+K">Kangda Zhi</a>, <a href="/search/eess?searchtype=author&query=Wu%2C+T">Tuo Wu</a>, <a href="/search/eess?searchtype=author&query=Jin%2C+M">Ming Jin</a>, <a href="/search/eess?searchtype=author&query=Pan%2C+C">Cunhua Pan</a>, <a href="/search/eess?searchtype=author&query=Elkashlan%2C+M">Maged Elkashlan</a>, <a href="/search/eess?searchtype=author&query=Yuen%2C+C">Chau Yuen</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.08141v1-abstract-short" style="display: inline;"> In this paper, we investigate reconfigurable intelligent surface (RIS)-assisted communication systems which involve a fixed-antenna base station (BS) and a mobile user (MU) that is equipped with fluid antenna system (FAS). Specifically, the RIS is utilized to enable communication for the user whose direct link from the base station is blocked by obstacles. We propose a comprehensive framework that… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.08141v1-abstract-full').style.display = 'inline'; document.getElementById('2407.08141v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.08141v1-abstract-full" style="display: none;"> In this paper, we investigate reconfigurable intelligent surface (RIS)-assisted communication systems which involve a fixed-antenna base station (BS) and a mobile user (MU) that is equipped with fluid antenna system (FAS). Specifically, the RIS is utilized to enable communication for the user whose direct link from the base station is blocked by obstacles. We propose a comprehensive framework that provides transmission design for both static scenarios with the knowledge of channel state information (CSI) and harsh environments where CSI is hard to acquire. It leads to two approaches: a CSI-based scheme where CSI is available, and a CSI-free scheme when CSI is inaccessible. Given the complex spatial correlations in FAS, we employ block-diagonal matrix approximation and independent antenna equivalent models to simplify the derivation of outage probabilities in both cases. Based on the derived outage probabilities, we then optimize the throughput of the FAS-RIS system. For the CSI-based scheme, we first propose a gradient ascent-based algorithm to obtain a near-optimal solution. Then, to address the possible high computational complexity in the gradient algorithm, we approximate the objective function and confirm a unique optimal solution accessible through a bisection search method. For the CSI-free scheme, we apply the partial gradient ascent algorithm, reducing complexity further than full gradient algorithms. We also approximate the objective function and derive a locally optimal closed-form solution to maximize throughput. Simulation results validate the effectiveness of the proposed framework for the transmission design in FAS-RIS systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.08141v1-abstract-full').style.display = 'none'; document.getElementById('2407.08141v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">submitted to IEEE journal for possible publication</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.05791">arXiv:2407.05791</a> <span> [<a href="https://arxiv.org/pdf/2407.05791">pdf</a>, <a href="https://arxiv.org/format/2407.05791">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Joint Beamforming and Antenna Design for Near-Field Fluid Antenna System </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Chen%2C+Y">Yixuan Chen</a>, <a href="/search/eess?searchtype=author&query=Chen%2C+M">Mingzhe Chen</a>, <a href="/search/eess?searchtype=author&query=Xu%2C+H">Hao Xu</a>, <a href="/search/eess?searchtype=author&query=Yang%2C+Z">Zhaohui Yang</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Zhang%2C+Z">Zhaoyang Zhang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.05791v2-abstract-short" style="display: inline;"> In this letter, we study the energy efficiency maximization problem for a fluid antenna system (FAS) in near field communications. Specifically, we consider a point-to-point near-field system where the base station (BS) transmitter has multiple fixed-position antennas and the user receives the signals with multiple fluid antennas. Our objective is to jointly optimize the transmit beamforming of th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.05791v2-abstract-full').style.display = 'inline'; document.getElementById('2407.05791v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.05791v2-abstract-full" style="display: none;"> In this letter, we study the energy efficiency maximization problem for a fluid antenna system (FAS) in near field communications. Specifically, we consider a point-to-point near-field system where the base station (BS) transmitter has multiple fixed-position antennas and the user receives the signals with multiple fluid antennas. Our objective is to jointly optimize the transmit beamforming of the BS and the fluid antenna positions at the user for maximizing the energy efficiency. Our scheme is based on an alternating optimization algorithm that iteratively solves the beamforming and antenna position subproblems. Our simulation results validate the performance improvement of the proposed algorithm and confirm the effectiveness of FAS. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.05791v2-abstract-full').style.display = 'none'; document.getElementById('2407.05791v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.03449">arXiv:2407.03449</a> <span> [<a href="https://arxiv.org/pdf/2407.03449">pdf</a>, <a href="https://arxiv.org/format/2407.03449">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> A Tutorial on Fluid Antenna System for 6G Networks: Encompassing Communication Theory, Optimization Methods and Hardware Designs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=New%2C+W+K">Wee Kiat New</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Xu%2C+H">Hao Xu</a>, <a href="/search/eess?searchtype=author&query=Wang%2C+C">Chao Wang</a>, <a href="/search/eess?searchtype=author&query=Ghadi%2C+F+R">Farshad Rostami Ghadi</a>, <a href="/search/eess?searchtype=author&query=Zhang%2C+J">Jichen Zhang</a>, <a href="/search/eess?searchtype=author&query=Rao%2C+J">Junhui Rao</a>, <a href="/search/eess?searchtype=author&query=Murch%2C+R">Ross Murch</a>, <a href="/search/eess?searchtype=author&query=Ram%C3%ADrez-Espinosa%2C+P">Pablo Ram铆rez-Espinosa</a>, <a href="/search/eess?searchtype=author&query=Morales-Jimenez%2C+D">David Morales-Jimenez</a>, <a href="/search/eess?searchtype=author&query=Chae%2C+C">Chan-Byoung Chae</a>, <a href="/search/eess?searchtype=author&query=Tong%2C+K">Kin-Fai Tong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.03449v2-abstract-short" style="display: inline;"> The advent of the sixth-generation (6G) networks presents another round of revolution for the mobile communication landscape, promising an immersive experience, robust reliability, minimal latency, extreme connectivity, ubiquitous coverage, and capabilities beyond communication, including intelligence and sensing. To achieve these ambitious goals, it is apparent that 6G networks need to incorporat… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.03449v2-abstract-full').style.display = 'inline'; document.getElementById('2407.03449v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.03449v2-abstract-full" style="display: none;"> The advent of the sixth-generation (6G) networks presents another round of revolution for the mobile communication landscape, promising an immersive experience, robust reliability, minimal latency, extreme connectivity, ubiquitous coverage, and capabilities beyond communication, including intelligence and sensing. To achieve these ambitious goals, it is apparent that 6G networks need to incorporate the state-of-the-art technologies. One of the technologies that has garnered rising interest is fluid antenna system (FAS) which represents any software-controllable fluidic, conductive, or dielectric structure capable of dynamically changing its shape and position to reconfigure essential radio-frequency (RF) characteristics. Compared to traditional antenna systems (TASs) with fixed-position radiating elements, the core idea of FAS revolves around the unique flexibility of reconfiguring the radiating elements within a given space. One recent driver of FAS is the recognition of its position-flexibility as a new degree of freedom (dof) to harness diversity and multiplexing gains. In this paper, we provide a comprehensive tutorial, covering channel modeling, signal processing and estimation methods, information-theoretic insights, new multiple access techniques, and hardware designs. Moreover, we delineate the challenges of FAS and explore the potential of using FAS to improve the performance of other contemporary technologies. By providing insights and guidance, this tutorial paper serves to inspire researchers to explore new horizons and fully unleash the potential of FAS. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.03449v2-abstract-full').style.display = 'none'; document.getElementById('2407.03449v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">53 pages, 45 figures, 5 tables. Accepted by IEEE Communications Surveys and Tutorials</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.02400">arXiv:2407.02400</a> <span> [<a href="https://arxiv.org/pdf/2407.02400">pdf</a>, <a href="https://arxiv.org/ps/2407.02400">ps</a>, <a href="https://arxiv.org/format/2407.02400">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1109/LCOMM.2024.3418338">10.1109/LCOMM.2024.3418338 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Coding-Enhanced Cooperative Jamming for Secret Communication in Fluid Antenna Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Xu%2C+H">Hao Xu</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=New%2C+W+K">Wee Kiat New</a>, <a href="/search/eess?searchtype=author&query=Li%2C+G">Guyue Li</a>, <a href="/search/eess?searchtype=author&query=Ghadi%2C+F+R">Farshad Rostami Ghadi</a>, <a href="/search/eess?searchtype=author&query=Zhu%2C+Y">Yongxu Zhu</a>, <a href="/search/eess?searchtype=author&query=Jin%2C+S">Shi Jin</a>, <a href="/search/eess?searchtype=author&query=Chae%2C+C">Chan-Byoung Chae</a>, <a href="/search/eess?searchtype=author&query=Zhang%2C+Y">Yangyang Zhang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.02400v1-abstract-short" style="display: inline;"> This letter investigates the secret communication problem for a fluid antenna system (FAS)-assisted wiretap channel, where the legitimate transmitter transmits an information-bearing signal to the legitimate receiver, and at the same time, transmits a jamming signal to interfere with the eavesdropper (Eve). Unlike the conventional jamming scheme, which usually transmits Gaussian noise that interfe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02400v1-abstract-full').style.display = 'inline'; document.getElementById('2407.02400v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.02400v1-abstract-full" style="display: none;"> This letter investigates the secret communication problem for a fluid antenna system (FAS)-assisted wiretap channel, where the legitimate transmitter transmits an information-bearing signal to the legitimate receiver, and at the same time, transmits a jamming signal to interfere with the eavesdropper (Eve). Unlike the conventional jamming scheme, which usually transmits Gaussian noise that interferes not only with Eve but also with the legitimate receiver, in this letter, we consider that encoded codewords are transmitted to jam Eve. Then, by employing appropriate coding schemes, the legitimate receiver can successfully decode the jamming signal and then cancel the interference, while Eve cannot, even if it knows the codebooks. We aim to maximize the secrecy rate through port selection and power control. Although the problem is non-convex, we show that the optimal solution can be found. Simulation results show that by using the FAS technique and the proposed jamming scheme, the secrecy rate of the system can be significantly increased. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02400v1-abstract-full').style.display = 'none'; document.getElementById('2407.02400v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 3 figures, this paper has been accepted by IEEE Communications Letters</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.05499">arXiv:2406.05499</a> <span> [<a href="https://arxiv.org/pdf/2406.05499">pdf</a>, <a href="https://arxiv.org/format/2406.05499">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> A Pixel-based Reconfigurable Antenna Design for Fluid Antenna Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Zhang%2C+J">Jichen Zhang</a>, <a href="/search/eess?searchtype=author&query=Rao%2C+J">Junhui Rao</a>, <a href="/search/eess?searchtype=author&query=Ming%2C+Z">Zhaoyang Ming</a>, <a href="/search/eess?searchtype=author&query=Li%2C+Z">Zan Li</a>, <a href="/search/eess?searchtype=author&query=Chiu%2C+C">Chi-Yuk Chiu</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Tong%2C+K">Kin-Fai Tong</a>, <a href="/search/eess?searchtype=author&query=Murch%2C+R">Ross Murch</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.05499v2-abstract-short" style="display: inline;"> Fluid Antenna Systems (FASs) have recently been proposed for enhancing the performance of wireless communication. Previous antenna designs to meet the requirements of FAS have been based on mechanically movable or liquid antennas and therefore have limited reconfiguration speeds. In this paper, we propose a design for a pixel-based reconfigurable antenna (PRA) that meets the requirements of FAS an… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.05499v2-abstract-full').style.display = 'inline'; document.getElementById('2406.05499v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.05499v2-abstract-full" style="display: none;"> Fluid Antenna Systems (FASs) have recently been proposed for enhancing the performance of wireless communication. Previous antenna designs to meet the requirements of FAS have been based on mechanically movable or liquid antennas and therefore have limited reconfiguration speeds. In this paper, we propose a design for a pixel-based reconfigurable antenna (PRA) that meets the requirements of FAS and the required switching speed. It can provide 12 FAS ports across 1/2 wavelength and consists of an E-slot patch antenna and an upper reconfigurable pixel layer with 6 RF switches. Simulation and experimental results from a prototype operating at 2.5 GHz demonstrate that the design can meet the requirements of FAS including port correlation with matched impedance. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.05499v2-abstract-full').style.display = 'none'; document.getElementById('2406.05499v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 16 figures, Submitted to IEEE Transations on Antennas and Propagation</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.05444">arXiv:2406.05444</a> <span> [<a href="https://arxiv.org/pdf/2406.05444">pdf</a>, <a href="https://arxiv.org/format/2406.05444">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Systems and Control">eess.SY</span> </div> </div> <p class="title is-5 mathjax"> A Generalized Pointing Error Model for FSO Links with Fixed-Wing UAVs for 6G: Analysis and Trajectory Optimization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Moon%2C+H">Hyung-Joo Moon</a>, <a href="/search/eess?searchtype=author&query=Chae%2C+C">Chan-Byoung Chae</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Alouini%2C+M">Mohamed-Slim Alouini</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.05444v1-abstract-short" style="display: inline;"> Free-space optical (FSO) communication is a promising solution to support wireless backhaul links in emerging 6G non-terrestrial networks. At the link level, pointing errors in FSO links can significantly impact capacity, making accurate modeling of these errors essential for both assessing and enhancing communication performance. In this paper, we introduce a novel model for FSO pointing errors i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.05444v1-abstract-full').style.display = 'inline'; document.getElementById('2406.05444v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.05444v1-abstract-full" style="display: none;"> Free-space optical (FSO) communication is a promising solution to support wireless backhaul links in emerging 6G non-terrestrial networks. At the link level, pointing errors in FSO links can significantly impact capacity, making accurate modeling of these errors essential for both assessing and enhancing communication performance. In this paper, we introduce a novel model for FSO pointing errors in unmanned aerial vehicles (UAVs) that incorporates three-dimensional (3D) jitter, including roll, pitch, and yaw angle jittering. We derive a probability density function for the pointing error angle based on the relative position and posture of the UAV to the ground station. This model is then integrated into a trajectory optimization problem designed to maximize energy efficiency while meeting constraints on speed, acceleration, and elevation angle. Our proposed optimization method significantly improves energy efficiency by adjusting the UAV's flight trajectory to minimize exposure to directions highly affected by jitter. The simulation results emphasize the importance of using UAV-specific 3D jitter models in achieving accurate performance measurements and effective system optimization in FSO communication networks. Utilizing our generalized model, the optimized trajectories achieve up to 11.8 percent higher energy efficiency compared to those derived from conventional Gaussian pointing error models. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.05444v1-abstract-full').style.display = 'none'; document.getElementById('2406.05444v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 12 figures, under revision; IEEE Transactions on Wireless Communications</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.03098">arXiv:2406.03098</a> <span> [<a href="https://arxiv.org/pdf/2406.03098">pdf</a>, <a href="https://arxiv.org/ps/2406.03098">ps</a>, <a href="https://arxiv.org/format/2406.03098">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> A Data and Model-Driven Deep Learning Approach to Robust Downlink Beamforming Optimization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Liang%2C+K">Kai Liang</a>, <a href="/search/eess?searchtype=author&query=Zheng%2C+G">Gan Zheng</a>, <a href="/search/eess?searchtype=author&query=Li%2C+Z">Zan Li</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Chae%2C+C">Chan-Byoung Chae</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.03098v1-abstract-short" style="display: inline;"> This paper investigates the optimization of the long-standing probabilistically robust transmit beamforming problem with channel uncertainties in the multiuser multiple-input single-output (MISO) downlink transmission. This problem poses significant analytical and computational challenges. Currently, the state-of-the-art optimization method relies on convex restrictions as tractable approximations… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.03098v1-abstract-full').style.display = 'inline'; document.getElementById('2406.03098v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.03098v1-abstract-full" style="display: none;"> This paper investigates the optimization of the long-standing probabilistically robust transmit beamforming problem with channel uncertainties in the multiuser multiple-input single-output (MISO) downlink transmission. This problem poses significant analytical and computational challenges. Currently, the state-of-the-art optimization method relies on convex restrictions as tractable approximations to ensure robustness against Gaussian channel uncertainties. However, this method not only exhibits high computational complexity and suffers from the rank relaxation issue but also yields conservative solutions. In this paper, we propose an unsupervised deep learning-based approach that incorporates the sampling of channel uncertainties in the training process to optimize the probabilistic system performance. We introduce a model-driven learning approach that defines a new beamforming structure with trainable parameters to account for channel uncertainties. Additionally, we employ a graph neural network to efficiently infer the key beamforming parameters. We successfully apply this approach to the minimum rate quantile maximization problem subject to outage and total power constraints. Furthermore, we propose a bisection search method to address the more challenging power minimization problem with probabilistic rate constraints by leveraging the aforementioned approach. Numerical results confirm that our approach achieves non-conservative robust performance, higher data rates, greater power efficiency, and faster execution compared to state-of-the-art optimization methods. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.03098v1-abstract-full').style.display = 'none'; document.getElementById('2406.03098v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">This paper has been accepted for publication in the IEEE Journal on Selected Areas in Communications, Special Issue on Advanced Optimization Theory and Algorithms for Next Generation Wireless Communication Networks</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.15607">arXiv:2405.15607</a> <span> [<a href="https://arxiv.org/pdf/2405.15607">pdf</a>, <a href="https://arxiv.org/format/2405.15607">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Channel Estimation and Reconstruction in Fluid Antenna System: Oversampling is Essential </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=New%2C+W+K">Wee Kiat New</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Xu%2C+H">Hao Xu</a>, <a href="/search/eess?searchtype=author&query=Ghadi%2C+F+R">Farshad Rostami Ghadi</a>, <a href="/search/eess?searchtype=author&query=Murch%2C+R">Ross Murch</a>, <a href="/search/eess?searchtype=author&query=Chae%2C+C">Chan-Byoung Chae</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.15607v2-abstract-short" style="display: inline;"> Fluid antenna system (FAS) has recently surfaced as a promising technology for the upcoming sixth generation (6G) wireless networks. Unlike traditional antenna system (TAS) with fixed antenna location, FAS introduces a flexible component in which the radiating element can switch its position within a predefined space. This capability allows FAS to achieve additional diversity and multiplexing gain… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.15607v2-abstract-full').style.display = 'inline'; document.getElementById('2405.15607v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.15607v2-abstract-full" style="display: none;"> Fluid antenna system (FAS) has recently surfaced as a promising technology for the upcoming sixth generation (6G) wireless networks. Unlike traditional antenna system (TAS) with fixed antenna location, FAS introduces a flexible component in which the radiating element can switch its position within a predefined space. This capability allows FAS to achieve additional diversity and multiplexing gains. Nevertheless, to fully reap the benefits of FAS, obtaining channel state information (CSI) over the predefined space is crucial. In this paper, we study the system with a transmitter equipped with a traditional fixed antenna and a receiver with a fluid antenna by considering an electromagnetic-compliant channel model. We address the challenges of channel estimation and reconstruction using Nyquist sampling and maximum likelihood estimation (MLE) methods. Our analysis reveals a fundamental tradeoff between the accuracy of the reconstructed channel and the number of estimated channels, indicating that half-wavelength sampling is insufficient for perfect reconstruction and that oversampling is essential to enhance accuracy. Despite its advantages, oversampling can introduce practical challenges. Consequently, we propose a suboptimal sampling distance that facilitates efficient channel reconstruction. In addition, we employ the MLE method to bound the channel estimation error by $蔚$, with a specific confidence interval (CI). Our findings enable us to determine the minimum number of estimated channels and the total number of pilot symbols required for efficient channel reconstruction in a given space. Lastly, we investigate the rate performance of FAS and TAS and demonstrate that FAS with imperfect CSI can outperform TAS with perfect CSI. In contrast to existing works, we also show that there is an optimal fluid antenna size that maximizes the achievable rate. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.15607v2-abstract-full').style.display = 'none'; document.getElementById('2405.15607v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 16 figures - including subfigures. Accepted by IEEE TWC</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.11520">arXiv:2405.11520</a> <span> [<a href="https://arxiv.org/pdf/2405.11520">pdf</a>, <a href="https://arxiv.org/format/2405.11520">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> On Performance of FAS-aided Wireless Powered NOMA Communication Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Ghadi%2C+F+R">Farshad Rostami Ghadi</a>, <a href="/search/eess?searchtype=author&query=Kaveh%2C+M">Masoud Kaveh</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Jantti%2C+R">Riku Jantti</a>, <a href="/search/eess?searchtype=author&query=Yan%2C+Z">Zheng Yan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.11520v2-abstract-short" style="display: inline;"> This paper studies the performance of a wireless powered communication network (WPCN) under the non-orthogonal multiple access (NOMA) scheme, where users take advantage of an emerging fluid antenna system (FAS). More precisely, we consider a scenario where a transmitter is powered by a remote power beacon (PB) to send information to the planar NOMA FAS-equipped users through Rayleigh fading channe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.11520v2-abstract-full').style.display = 'inline'; document.getElementById('2405.11520v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.11520v2-abstract-full" style="display: none;"> This paper studies the performance of a wireless powered communication network (WPCN) under the non-orthogonal multiple access (NOMA) scheme, where users take advantage of an emerging fluid antenna system (FAS). More precisely, we consider a scenario where a transmitter is powered by a remote power beacon (PB) to send information to the planar NOMA FAS-equipped users through Rayleigh fading channels. After introducing the distribution of the equivalent channel coefficients to the users, we derive compact analytical expressions for the outage probability (OP) in order to evaluate the system performance. Additionally, we present asymptotic OP in the high signal-to-noise ratio (SNR) regime. Eventually, results reveal that deploying the FAS with only one activated port in NOMA users can significantly enhance the WPCN performance compared with using traditional antenna systems (TAS). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.11520v2-abstract-full').style.display = 'none'; document.getElementById('2405.11520v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 19 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">This manuscript has been submitted to the 20th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.11306">arXiv:2405.11306</a> <span> [<a href="https://arxiv.org/pdf/2405.11306">pdf</a>, <a href="https://arxiv.org/format/2405.11306">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Meta Reinforcement Learning for Resource Allocation in Multi-Antenna UAV Network with Rate Splitting Multiple Access </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Zarini%2C+H">Hosein Zarini</a>, <a href="/search/eess?searchtype=author&query=Dehkordi%2C+M+F">Maryam Farajzadeh Dehkordi</a>, <a href="/search/eess?searchtype=author&query=Farhadi%2C+A">Armin Farhadi</a>, <a href="/search/eess?searchtype=author&query=Mili%2C+M+R">Mohammad Robat Mili</a>, <a href="/search/eess?searchtype=author&query=Movaghar%2C+A">Ali Movaghar</a>, <a href="/search/eess?searchtype=author&query=Rasti%2C+M">Mehdi Rasti</a>, <a href="/search/eess?searchtype=author&query=Li%2C+Y">Yonghui Li</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.11306v1-abstract-short" style="display: inline;"> Unmanned aerial vehicles (UAVs) with multiple antennas have recently been explored to improve capacity in wireless networks. However, the strict energy constraint of UAVs, given their simultaneous flying and communication tasks, renders the exploration of energy-efficient multi-antenna techniques indispensable for UAVs. Meanwhile, lens antenna subarray (LAS) emerges as a promising energy-efficient… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.11306v1-abstract-full').style.display = 'inline'; document.getElementById('2405.11306v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.11306v1-abstract-full" style="display: none;"> Unmanned aerial vehicles (UAVs) with multiple antennas have recently been explored to improve capacity in wireless networks. However, the strict energy constraint of UAVs, given their simultaneous flying and communication tasks, renders the exploration of energy-efficient multi-antenna techniques indispensable for UAVs. Meanwhile, lens antenna subarray (LAS) emerges as a promising energy-efficient solution that has not been previously harnessed for this purpose. In this paper, we propose a LAS-aided multi-antenna UAV to serve ground users in the downlink transmission of the terahertz (THz) band, utilizing rate splitting multiple access (RSMA) for effective beam division multiplexing. We formulate an optimization problem of maximizing the total system spectral efficiency (SE). This involves optimizing the UAV's transmit beamforming and the common rate of RSMA. By recasting the optimization problem into a Markov decision process (MDP), we propose a deep deterministic policy gradient (DDPG)-based resource allocation mechanism tailored to capture problem dynamics and optimize its variables. Moreover, given the UAV's frequent mobility and consequential system reconfigurations, we fortify the trained DDPG model with a meta-learning strategy, enhancing its adaptability to system variations. Numerically, more than 20\% energy efficiency gain is achieved by our proposed LAS-aided multi-antenna UAV equipped with 4 lenses, compared to a single-lens UAV. Simulations also demonstrate that at a signal-to-noise (SNR) of 10 dB, the incorporation of RSMA results in a 22\% SE enhancement over conventional orthogonal beam division multiple access. Furthermore, the overall system SE improves by 27\%, when meta-learning is employed for fine-tuning the conventional DDPG method in literature. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.11306v1-abstract-full').style.display = 'none'; document.getElementById('2405.11306v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.09663">arXiv:2405.09663</a> <span> [<a href="https://arxiv.org/pdf/2405.09663">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Design and Implementation of mmWave Surface Wave Enabled Fluid Antennas and Experimental Results for Fluid Antenna Multiple Access </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Shen%2C+Y">Yuanjun Shen</a>, <a href="/search/eess?searchtype=author&query=Tang%2C+B">Boyi Tang</a>, <a href="/search/eess?searchtype=author&query=Gao%2C+S">Shuai Gao</a>, <a href="/search/eess?searchtype=author&query=Tong%2C+K">Kin-Fai Tong</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+H">Hang Wong</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Zhang%2C+Y">Yangyang Zhang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.09663v1-abstract-short" style="display: inline;"> While multiple-input multiple-output (MIMO) technologies continue to advance, concerns arise as to how MIMO can remain scalable if more users are to be accommodated with an increasing number of antennas at the base station (BS) in the upcoming sixth generation (6G). Recently, the concept of fluid antenna system (FAS) has emerged, which promotes position flexibility to enable transmitter channel st… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.09663v1-abstract-full').style.display = 'inline'; document.getElementById('2405.09663v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.09663v1-abstract-full" style="display: none;"> While multiple-input multiple-output (MIMO) technologies continue to advance, concerns arise as to how MIMO can remain scalable if more users are to be accommodated with an increasing number of antennas at the base station (BS) in the upcoming sixth generation (6G). Recently, the concept of fluid antenna system (FAS) has emerged, which promotes position flexibility to enable transmitter channel state information (CSI) free spatial multiple access on one radio frequency (RF) chain. On the theoretical side, the fluid antenna multiple access (FAMA) approach offers a scalable alternative to massive MIMO spatial multiplexing. However, FAMA lacks experimental validation and the hardware implementation of FAS remains a mysterious approach. The aim of this paper is to provide a novel hardware design for FAS and evaluate the performance of FAMA using experimental data. Our FAS design is based on a dynamically reconfigurable "fluid" radiator which is capable of adjusting its position within a predefined space. One single-channel fluid antenna (SCFA) and one double-channel fluid antenna (DCFA) are designed, electromagnetically simulated, fabricated, and measured. The measured radiation patterns of prototypes are imported into channel and network models for evaluating their performance in FAMA. The experimental results demonstrate that in the 5G millimeter-wave (mmWave) bands (24-30 GHz), the FAS prototypes can vary their gain up to an averaged value of 11 dBi. In the case of 4-user FAMA, the double-channel FAS can significantly reduce outage probability by 57% and increases the multiplexing gain to 2.27 when compared to a static omnidirectional antenna. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.09663v1-abstract-full').style.display = 'none'; document.getElementById('2405.09663v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to IEEE Transactions on Antennas and Propagation</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.05715">arXiv:2405.05715</a> <span> [<a href="https://arxiv.org/pdf/2405.05715">pdf</a>, <a href="https://arxiv.org/format/2405.05715">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Shifting the ISAC Trade-Off with Fluid Antenna Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Zou%2C+J">Jiaqi Zou</a>, <a href="/search/eess?searchtype=author&query=Xu%2C+H">Hao Xu</a>, <a href="/search/eess?searchtype=author&query=Wang%2C+C">Chao Wang</a>, <a href="/search/eess?searchtype=author&query=Xu%2C+L">Lvxin Xu</a>, <a href="/search/eess?searchtype=author&query=Sun%2C+S">Songlin Sun</a>, <a href="/search/eess?searchtype=author&query=Meng%2C+K">Kaitao Meng</a>, <a href="/search/eess?searchtype=author&query=Masouros%2C+C">Christos Masouros</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.05715v1-abstract-short" style="display: inline;"> As an emerging antenna technology, a fluid antenna system (FAS) enhances spatial diversity to improve both sensing and communication performance by shifting the active antennas among available ports. In this letter, we study the potential of shifting the integrated sensing and communication (ISAC) trade-off with FAS. We propose the model for FAS-enabled ISAC and jointly optimize the transmit beamf… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.05715v1-abstract-full').style.display = 'inline'; document.getElementById('2405.05715v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.05715v1-abstract-full" style="display: none;"> As an emerging antenna technology, a fluid antenna system (FAS) enhances spatial diversity to improve both sensing and communication performance by shifting the active antennas among available ports. In this letter, we study the potential of shifting the integrated sensing and communication (ISAC) trade-off with FAS. We propose the model for FAS-enabled ISAC and jointly optimize the transmit beamforming and port selection of FAS. In particular, we aim to minimize the transmit power, while satisfying both communication and sensing requirements. An efficient iterative algorithm based on sparse optimization, convex approximation, and a penalty approach is developed. The simulation results show that the proposed scheme can attain 33% reductions in transmit power with guaranteed sensing and communication performance, showing the great potential of the fluid antenna for striking a flexible tradeoff between sensing and communication in ISAC systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.05715v1-abstract-full').style.display = 'none'; document.getElementById('2405.05715v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.00032">arXiv:2404.00032</a> <span> [<a href="https://arxiv.org/pdf/2404.00032">pdf</a>, <a href="https://arxiv.org/format/2404.00032">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Human-Computer Interaction">cs.HC</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Image and Video Processing">eess.IV</span> </div> </div> <p class="title is-5 mathjax"> Deployment of Deep Learning Model in Real World Clinical Setting: A Case Study in Obstetric Ultrasound </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Wong%2C+C+K">Chun Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Ngo%2C+M">Mary Ngo</a>, <a href="/search/eess?searchtype=author&query=Lin%2C+M">Manxi Lin</a>, <a href="/search/eess?searchtype=author&query=Bashir%2C+Z">Zahra Bashir</a>, <a href="/search/eess?searchtype=author&query=Heen%2C+A">Amihai Heen</a>, <a href="/search/eess?searchtype=author&query=Svendsen%2C+M+B+S">Morten Bo S酶ndergaard Svendsen</a>, <a href="/search/eess?searchtype=author&query=Tolsgaard%2C+M+G">Martin Gr酶nneb忙k Tolsgaard</a>, <a href="/search/eess?searchtype=author&query=Christensen%2C+A+N">Anders Nymark Christensen</a>, <a href="/search/eess?searchtype=author&query=Feragen%2C+A">Aasa Feragen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.00032v1-abstract-short" style="display: inline;"> Despite the rapid development of AI models in medical image analysis, their validation in real-world clinical settings remains limited. To address this, we introduce a generic framework designed for deploying image-based AI models in such settings. Using this framework, we deployed a trained model for fetal ultrasound standard plane detection, and evaluated it in real-time sessions with both novic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.00032v1-abstract-full').style.display = 'inline'; document.getElementById('2404.00032v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.00032v1-abstract-full" style="display: none;"> Despite the rapid development of AI models in medical image analysis, their validation in real-world clinical settings remains limited. To address this, we introduce a generic framework designed for deploying image-based AI models in such settings. Using this framework, we deployed a trained model for fetal ultrasound standard plane detection, and evaluated it in real-time sessions with both novice and expert users. Feedback from these sessions revealed that while the model offers potential benefits to medical practitioners, the need for navigational guidance was identified as a key area for improvement. These findings underscore the importance of early deployment of AI models in real-world settings, leading to insights that can guide the refinement of the model and system based on actual user feedback. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.00032v1-abstract-full').style.display = 'none'; document.getElementById('2404.00032v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.17837">arXiv:2403.17837</a> <span> [<a href="https://arxiv.org/pdf/2403.17837">pdf</a>, <a href="https://arxiv.org/format/2403.17837">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Graphics">cs.GR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Multimedia">cs.MM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Image and Video Processing">eess.IV</span> </div> </div> <p class="title is-5 mathjax"> GTA-HDR: A Large-Scale Synthetic Dataset for HDR Image Reconstruction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Barua%2C+H+B">Hrishav Bakul Barua</a>, <a href="/search/eess?searchtype=author&query=Stefanov%2C+K">Kalin Stefanov</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">KokSheik Wong</a>, <a href="/search/eess?searchtype=author&query=Dhall%2C+A">Abhinav Dhall</a>, <a href="/search/eess?searchtype=author&query=Krishnasamy%2C+G">Ganesh Krishnasamy</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.17837v1-abstract-short" style="display: inline;"> High Dynamic Range (HDR) content (i.e., images and videos) has a broad range of applications. However, capturing HDR content from real-world scenes is expensive and time-consuming. Therefore, the challenging task of reconstructing visually accurate HDR images from their Low Dynamic Range (LDR) counterparts is gaining attention in the vision research community. A major challenge in this research pr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.17837v1-abstract-full').style.display = 'inline'; document.getElementById('2403.17837v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.17837v1-abstract-full" style="display: none;"> High Dynamic Range (HDR) content (i.e., images and videos) has a broad range of applications. However, capturing HDR content from real-world scenes is expensive and time-consuming. Therefore, the challenging task of reconstructing visually accurate HDR images from their Low Dynamic Range (LDR) counterparts is gaining attention in the vision research community. A major challenge in this research problem is the lack of datasets, which capture diverse scene conditions (e.g., lighting, shadows, weather, locations, landscapes, objects, humans, buildings) and various image features (e.g., color, contrast, saturation, hue, luminance, brightness, radiance). To address this gap, in this paper, we introduce GTA-HDR, a large-scale synthetic dataset of photo-realistic HDR images sampled from the GTA-V video game. We perform thorough evaluation of the proposed dataset, which demonstrates significant qualitative and quantitative improvements of the state-of-the-art HDR image reconstruction methods. Furthermore, we demonstrate the effectiveness of the proposed dataset and its impact on additional computer vision tasks including 3D human pose estimation, human body part segmentation, and holistic scene segmentation. The dataset, data collection pipeline, and evaluation code are available at: https://github.com/HrishavBakulBarua/GTA-HDR. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.17837v1-abstract-full').style.display = 'none'; document.getElementById('2403.17837v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to IEEE</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">MSC Class:</span> Artificial intelligence; Computer vision; Machine learning; Deep learning <span class="has-text-black-bis has-text-weight-semibold">ACM Class:</span> I.3.3; I.4.5 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.17265">arXiv:2403.17265</a> <span> [<a href="https://arxiv.org/pdf/2403.17265">pdf</a>, <a href="https://arxiv.org/format/2403.17265">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Cache-Enabled Millimetre-Wave Fluid Antenna Systems: Modeling and Performance </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Ghadi%2C+F+R">Farshad Rostami Ghadi</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Tong%2C+K">Kin-Fai Tong</a>, <a href="/search/eess?searchtype=author&query=Zhang%2C+Y">Yangyang Zhang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.17265v1-abstract-short" style="display: inline;"> This letter investigates the performance of content caching in a heterogeneous cellular network (HetNet) consisting of fluid antenna system (FAS)-equipped mobile users (MUs) and millimeter-wave (mm-wave) single-antenna small base stations (SBSs), distributed according to the independent homogeneous Poisson point processes (HPPP). In particular, it is assumed that the most popular contents are cach… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.17265v1-abstract-full').style.display = 'inline'; document.getElementById('2403.17265v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.17265v1-abstract-full" style="display: none;"> This letter investigates the performance of content caching in a heterogeneous cellular network (HetNet) consisting of fluid antenna system (FAS)-equipped mobile users (MUs) and millimeter-wave (mm-wave) single-antenna small base stations (SBSs), distributed according to the independent homogeneous Poisson point processes (HPPP). In particular, it is assumed that the most popular contents are cached in the SBSs to serve the FAS-equipped MUs requests. To assess the system performance, we derive compact expressions for the successful content delivery probability (SCDP) and the content delivery delay (CDD) using the Gauss-Laguerre quadrature technique. Our numerical results show that the performance of cache-enabled mm-wave HetNets can be greatly improved, when the FAS is utilized at the MUs instead of traditional fixed-antenna system deployment. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.17265v1-abstract-full').style.display = 'none'; document.getElementById('2403.17265v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.08648">arXiv:2403.08648</a> <span> [<a href="https://arxiv.org/pdf/2403.08648">pdf</a>, <a href="https://arxiv.org/format/2403.08648">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Meta Reinforcement Learning for Resource Allocation in Aerial Active-RIS-assisted Networks with Rate-Splitting Multiple Access </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Faramarzi%2C+S">Sajad Faramarzi</a>, <a href="/search/eess?searchtype=author&query=Javadi%2C+S">Sepideh Javadi</a>, <a href="/search/eess?searchtype=author&query=Zeinali%2C+F">Farshad Zeinali</a>, <a href="/search/eess?searchtype=author&query=Zarini%2C+H">Hosein Zarini</a>, <a href="/search/eess?searchtype=author&query=Mili%2C+M+R">Mohammad Robat Mili</a>, <a href="/search/eess?searchtype=author&query=Bennis%2C+M">Mehdi Bennis</a>, <a href="/search/eess?searchtype=author&query=Li%2C+Y">Yonghui Li</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.08648v1-abstract-short" style="display: inline;"> Mounting a reconfigurable intelligent surface (RIS) on an unmanned aerial vehicle (UAV) holds promise for improving traditional terrestrial network performance. Unlike conventional methods deploying passive RIS on UAVs, this study delves into the efficacy of an aerial active RIS (AARIS). Specifically, the downlink transmission of an AARIS network is investigated, where the base station (BS) levera… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.08648v1-abstract-full').style.display = 'inline'; document.getElementById('2403.08648v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.08648v1-abstract-full" style="display: none;"> Mounting a reconfigurable intelligent surface (RIS) on an unmanned aerial vehicle (UAV) holds promise for improving traditional terrestrial network performance. Unlike conventional methods deploying passive RIS on UAVs, this study delves into the efficacy of an aerial active RIS (AARIS). Specifically, the downlink transmission of an AARIS network is investigated, where the base station (BS) leverages rate-splitting multiple access (RSMA) for effective interference management and benefits from the support of an AARIS for jointly amplifying and reflecting the BS's transmit signals. Considering both the non-trivial energy consumption of the active RIS and the limited energy storage of the UAV, we propose an innovative element selection strategy for optimizing the on/off status of RIS elements, which adaptively and remarkably manages the system's power consumption. To this end, a resource management problem is formulated, aiming to maximize the system energy efficiency (EE) by jointly optimizing the transmit beamforming at the BS, the element activation, the phase shift and the amplification factor at the RIS, the RSMA common data rate at users, as well as the UAV's trajectory. Due to the dynamicity nature of UAV and user mobility, a deep reinforcement learning (DRL) algorithm is designed for resource allocation, utilizing meta-learning to adaptively handle fast time-varying system dynamics. Simulations indicate that incorporating an active RIS at the UAV leads to substantial EE gain, compared to passive RIS-aided UAV. We observe the superiority of the RSMA-based AARIS system in terms of EE, compared to existing approaches adopting non-orthogonal multiple access (NOMA). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.08648v1-abstract-full').style.display = 'none'; document.getElementById('2403.08648v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.03756">arXiv:2403.03756</a> <span> [<a href="https://arxiv.org/pdf/2403.03756">pdf</a>, <a href="https://arxiv.org/ps/2403.03756">ps</a>, <a href="https://arxiv.org/format/2403.03756">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Maximizing Energy Charging for UAV-assisted MEC Systems with SWIPT </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Hu%2C+X">Xiaoyan Hu</a>, <a href="/search/eess?searchtype=author&query=Wen%2C+P">Pengle Wen</a>, <a href="/search/eess?searchtype=author&query=Xiao%2C+H">Han Xiao</a>, <a href="/search/eess?searchtype=author&query=Wang%2C+W">Wenjie Wang</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.03756v1-abstract-short" style="display: inline;"> A Unmanned aerial vehicle (UAV)-assisted mobile edge computing (MEC) scheme with simultaneous wireless information and power transfer (SWIPT) is proposed in this paper. Unlike existing MEC-WPT schemes that disregard the downlink period for returning computing results to the ground equipment (GEs), our proposed scheme actively considers and capitalizes on this period. By leveraging the SWIPT techni… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.03756v1-abstract-full').style.display = 'inline'; document.getElementById('2403.03756v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.03756v1-abstract-full" style="display: none;"> A Unmanned aerial vehicle (UAV)-assisted mobile edge computing (MEC) scheme with simultaneous wireless information and power transfer (SWIPT) is proposed in this paper. Unlike existing MEC-WPT schemes that disregard the downlink period for returning computing results to the ground equipment (GEs), our proposed scheme actively considers and capitalizes on this period. By leveraging the SWIPT technique, the UAV can simultaneously transmit energy and the computing results during the downlink period. In this scheme, our objective is to maximize the remaining energy among all GEs by jointly optimizing computing task scheduling, UAV transmit and receive beamforming, BS receive beamforming, GEs' transmit power and power splitting ratio for information decoding, time scheduling, and UAV trajectory. We propose an alternating optimization algorithm that utilizes the semidefinite relaxation (SDR), singular value decomposition (SVD), and fractional programming (FP) methods to effectively solve the nonconvex problem. Numerous experiments validate the effectiveness of the proposed scheme. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.03756v1-abstract-full').style.display = 'none'; document.getElementById('2403.03756v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.00453">arXiv:2403.00453</a> <span> [<a href="https://arxiv.org/pdf/2403.00453">pdf</a>, <a href="https://arxiv.org/ps/2403.00453">ps</a>, <a href="https://arxiv.org/format/2403.00453">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Exploring Fairness for FAS-assisted Communication Systems: from NOMA to OMA </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Yao%2C+J">Junteng Yao</a>, <a href="/search/eess?searchtype=author&query=Zhou%2C+L">Liaoshi Zhou</a>, <a href="/search/eess?searchtype=author&query=Wu%2C+T">Tuo Wu</a>, <a href="/search/eess?searchtype=author&query=Jin%2C+M">Ming Jin</a>, <a href="/search/eess?searchtype=author&query=Pan%2C+C">Cunhua Pan</a>, <a href="/search/eess?searchtype=author&query=Elkashlan%2C+M">Maged Elkashlan</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.00453v1-abstract-short" style="display: inline;"> This paper addresses the fairness issue within fluid antenna system (FAS)-assisted non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA) systems, where a single fixed-antenna base station (BS) transmits superposition-coded signals to two users, each with a single fluid antenna. We define fairness through the minimization of the maximum outage probability for the two users, und… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.00453v1-abstract-full').style.display = 'inline'; document.getElementById('2403.00453v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.00453v1-abstract-full" style="display: none;"> This paper addresses the fairness issue within fluid antenna system (FAS)-assisted non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA) systems, where a single fixed-antenna base station (BS) transmits superposition-coded signals to two users, each with a single fluid antenna. We define fairness through the minimization of the maximum outage probability for the two users, under total resource constraints for both FAS-assisted NOMA and OMA systems. Specifically, in the FAS-assisted NOMA systems, we study both a special case and the general case, deriving a closed-form solution for the former and applying a bisection search method to find the optimal solution for the latter. Moreover, for the general case, we derive a locally optimal closed-form solution to achieve fairness. In the FAS-assisted OMA systems, to deal with the non-convex optimization problem with coupling of the variables in the objective function, we employ an approximation strategy to facilitate a successive convex approximation (SCA)-based algorithm, achieving locally optimal solutions for both cases. Empirical analysis validates that our proposed solutions outperform conventional NOMA and OMA benchmarks in terms of fairness. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.00453v1-abstract-full').style.display = 'none'; document.getElementById('2403.00453v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.19188">arXiv:2402.19188</a> <span> [<a href="https://arxiv.org/pdf/2402.19188">pdf</a>, <a href="https://arxiv.org/format/2402.19188">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> KGAMC: A Novel Knowledge Graph Driven Automatic Modulation Classification Scheme </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Li%2C+Y">Yike Li</a>, <a href="/search/eess?searchtype=author&query=Yua%2C+L">Lu Yua</a>, <a href="/search/eess?searchtype=author&query=Zhou%2C+F">Fuhui Zhou</a>, <a href="/search/eess?searchtype=author&query=Wu%2C+Q">Qihui Wu</a>, <a href="/search/eess?searchtype=author&query=Al-Dhahir%2C+N">Naofal Al-Dhahir</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.19188v2-abstract-short" style="display: inline;"> Automatic modulation classification (AMC) is a promising technology to realize intelligent wireless communications in the sixth generation (6G) wireless communication networks. Recently, many data-and-knowledge dual-driven AMC schemes have achieved high accuracy. However, most of these schemes focus on generating additional prior knowledge or features of blind signals, which consumes longer comput… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.19188v2-abstract-full').style.display = 'inline'; document.getElementById('2402.19188v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.19188v2-abstract-full" style="display: none;"> Automatic modulation classification (AMC) is a promising technology to realize intelligent wireless communications in the sixth generation (6G) wireless communication networks. Recently, many data-and-knowledge dual-driven AMC schemes have achieved high accuracy. However, most of these schemes focus on generating additional prior knowledge or features of blind signals, which consumes longer computation time and ignores the interpretability of the model learning process. To solve these problems, we propose a novel knowledge graph (KG) driven AMC (KGAMC) scheme by training the networks under the guidance of domain knowledge. A modulation knowledge graph (MKG) with the knowledge of modulation technical characteristics and application scenarios is constructed and a relation-graph convolution network (RGCN) is designed to extract knowledge of the MKG. This knowledge is utilized to facilitate the signal features separation of the data-oriented model by implementing a specialized feature aggregation method. Simulation results demonstrate that KGAMC achieves superior classification performance compared to other benchmark schemes, especially in the low signal-to-noise ratio (SNR) range. Furthermore, the signal features of the high-order modulation are more discriminative, thus reducing the confusion between similar signals. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.19188v2-abstract-full').style.display = 'none'; document.getElementById('2402.19188v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 29 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.18683">arXiv:2402.18683</a> <span> [<a href="https://arxiv.org/pdf/2402.18683">pdf</a>, <a href="https://arxiv.org/format/2402.18683">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Integrated Sensing and Communication Meets Smart Propagation Engineering: Opportunities and Challenges </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Meng%2C+K">Kaitao Meng</a>, <a href="/search/eess?searchtype=author&query=Masouros%2C+C">Christos Masouros</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Petropulu%2C+A+P">Athina P. Petropulu</a>, <a href="/search/eess?searchtype=author&query=Hanzo%2C+L">Lajos Hanzo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.18683v1-abstract-short" style="display: inline;"> Both smart propagation engineering as well as integrated sensing and communication (ISAC) constitute promising candidates for next-generation (NG) mobile networks. We provide a synergistic view of these technologies, and explore their mutual benefits. First, moving beyond just intelligent surfaces, we provide a holistic view of the engineering aspects of smart propagation environments. By delving… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.18683v1-abstract-full').style.display = 'inline'; document.getElementById('2402.18683v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.18683v1-abstract-full" style="display: none;"> Both smart propagation engineering as well as integrated sensing and communication (ISAC) constitute promising candidates for next-generation (NG) mobile networks. We provide a synergistic view of these technologies, and explore their mutual benefits. First, moving beyond just intelligent surfaces, we provide a holistic view of the engineering aspects of smart propagation environments. By delving into the fundamental characteristics of intelligent surfaces, fluid antennas, and unmanned aerial vehicles, we reveal that more efficient control of the pathloss and fading can be achieved, thus facilitating intrinsic integration and mutual assistance between sensing and communication functionalities. In turn, with the exploitation of the sensing capabilities of ISAC to orchestrate the efficient configuration of radio environments, both the computational effort and signaling overheads can be reduced. We present indicative simulation results, which verify that cooperative smart propagation environment design significantly enhances the ISAC performance. Finally, some promising directions are outlined for combining ISAC with smart propagation engineering. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.18683v1-abstract-full').style.display = 'none'; document.getElementById('2402.18683v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 5 figures, submitted to IEEE journal for possible publication</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.17502">arXiv:2402.17502</a> <span> [<a href="https://arxiv.org/pdf/2402.17502">pdf</a>, <a href="https://arxiv.org/format/2402.17502">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Image and Video Processing">eess.IV</span> </div> </div> <p class="title is-5 mathjax"> FedLPPA: Learning Personalized Prompt and Aggregation for Federated Weakly-supervised Medical Image Segmentation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Lin%2C+L">Li Lin</a>, <a href="/search/eess?searchtype=author&query=Liu%2C+Y">Yixiang Liu</a>, <a href="/search/eess?searchtype=author&query=Wu%2C+J">Jiewei Wu</a>, <a href="/search/eess?searchtype=author&query=Cheng%2C+P">Pujin Cheng</a>, <a href="/search/eess?searchtype=author&query=Cai%2C+Z">Zhiyuan Cai</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K+K+Y">Kenneth K. Y. Wong</a>, <a href="/search/eess?searchtype=author&query=Tang%2C+X">Xiaoying Tang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.17502v2-abstract-short" style="display: inline;"> Federated learning (FL) effectively mitigates the data silo challenge brought about by policies and privacy concerns, implicitly harnessing more data for deep model training. However, traditional centralized FL models grapple with diverse multi-center data, especially in the face of significant data heterogeneity, notably in medical contexts. In the realm of medical image segmentation, the growing… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.17502v2-abstract-full').style.display = 'inline'; document.getElementById('2402.17502v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.17502v2-abstract-full" style="display: none;"> Federated learning (FL) effectively mitigates the data silo challenge brought about by policies and privacy concerns, implicitly harnessing more data for deep model training. However, traditional centralized FL models grapple with diverse multi-center data, especially in the face of significant data heterogeneity, notably in medical contexts. In the realm of medical image segmentation, the growing imperative to curtail annotation costs has amplified the importance of weakly-supervised techniques which utilize sparse annotations such as points, scribbles, etc. A pragmatic FL paradigm shall accommodate diverse annotation formats across different sites, which research topic remains under-investigated. In such context, we propose a novel personalized FL framework with learnable prompt and aggregation (FedLPPA) to uniformly leverage heterogeneous weak supervision for medical image segmentation. In FedLPPA, a learnable universal knowledge prompt is maintained, complemented by multiple learnable personalized data distribution prompts and prompts representing the supervision sparsity. Integrated with sample features through a dual-attention mechanism, those prompts empower each local task decoder to adeptly adjust to both the local distribution and the supervision form. Concurrently, a dual-decoder strategy, predicated on prompt similarity, is introduced for enhancing the generation of pseudo-labels in weakly-supervised learning, alleviating overfitting and noise accumulation inherent to local data, while an adaptable aggregation method is employed to customize the task decoder on a parameter-wise basis. Extensive experiments on four distinct medical image segmentation tasks involving different modalities underscore the superiority of FedLPPA, with its efficacy closely parallels that of fully supervised centralized training. Our code and data will be available. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.17502v2-abstract-full').style.display = 'none'; document.getElementById('2402.17502v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 10 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.16116">arXiv:2402.16116</a> <span> [<a href="https://arxiv.org/pdf/2402.16116">pdf</a>, <a href="https://arxiv.org/format/2402.16116">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> On Performance of RIS-Aided Fluid Antenna Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Ghadi%2C+F+R">Farshad Rostami Ghadi</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=New%2C+W+K">Wee Kiat New</a>, <a href="/search/eess?searchtype=author&query=Xu%2C+H">Hao Xu</a>, <a href="/search/eess?searchtype=author&query=Murch%2C+R">Ross Murch</a>, <a href="/search/eess?searchtype=author&query=Zhang%2C+Y">Yangyang Zhang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.16116v1-abstract-short" style="display: inline;"> This letter studies the performance of reconfigurable intelligent surface (RIS)-aided communications for a fluid antenna system (FAS) enabled receiver. Specifically, a fixed singleantenna base station (BS) transmits information through a RIS to a mobile user (MU) which is equipped with a planar fluid antenna in the absence of a direct link.We first analyze the spatial correlation structures among… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.16116v1-abstract-full').style.display = 'inline'; document.getElementById('2402.16116v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.16116v1-abstract-full" style="display: none;"> This letter studies the performance of reconfigurable intelligent surface (RIS)-aided communications for a fluid antenna system (FAS) enabled receiver. Specifically, a fixed singleantenna base station (BS) transmits information through a RIS to a mobile user (MU) which is equipped with a planar fluid antenna in the absence of a direct link.We first analyze the spatial correlation structures among the positions (or ports) in the planar FAS, and then derive the joint distribution of the equivalent channel gain at the user by exploiting the central limit theorem. Furthermore, we obtain compact analytical expressions for the outage probability (OP) and delay outage rate (DOR). Numerical results illustrate that using FAS with only one activated port into the RIS-aided communication network can greatly enhance the performance, when compared to traditional antenna systems (TAS). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.16116v1-abstract-full').style.display = 'none'; document.getElementById('2402.16116v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.11294">arXiv:2402.11294</a> <span> [<a href="https://arxiv.org/pdf/2402.11294">pdf</a>, <a href="https://arxiv.org/format/2402.11294">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Power Optimization for Integrated Active and Passive Sensing in DFRC Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Lou%2C+X">Xingliang Lou</a>, <a href="/search/eess?searchtype=author&query=Xia%2C+W">Wenchao Xia</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Zhao%2C+H">Haitao Zhao</a>, <a href="/search/eess?searchtype=author&query=Quek%2C+T+Q+S">Tony Q. S. Quek</a>, <a href="/search/eess?searchtype=author&query=Zhu%2C+H">Hongbo Zhu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.11294v1-abstract-short" style="display: inline;"> Most existing works on dual-function radar-communication (DFRC) systems mainly focus on active sensing, but ignore passive sensing. To leverage multi-static sensing capability, we explore integrated active and passive sensing (IAPS) in DFRC systems to remedy sensing performance. The multi-antenna base station (BS) is responsible for communication and active sensing by transmitting signals to user… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.11294v1-abstract-full').style.display = 'inline'; document.getElementById('2402.11294v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.11294v1-abstract-full" style="display: none;"> Most existing works on dual-function radar-communication (DFRC) systems mainly focus on active sensing, but ignore passive sensing. To leverage multi-static sensing capability, we explore integrated active and passive sensing (IAPS) in DFRC systems to remedy sensing performance. The multi-antenna base station (BS) is responsible for communication and active sensing by transmitting signals to user equipments while detecting a target according to echo signals. In contrast, passive sensing is performed at the receive access points (RAPs). We consider both the cases where the capacity of the backhaul links between the RAPs and BS is unlimited or limited and adopt different fusion strategies. Specifically, when the backhaul capacity is unlimited, the BS and RAPs transfer sensing signals they have received to the central controller (CC) for signal fusion. The CC processes the signals and leverages the generalized likelihood ratio test detector to determine the present of a target. However, when the backhaul capacity is limited, each RAP, as well as the BS, makes decisions independently and sends its binary inference results to the CC for result fusion via voting aggregation. Then, aiming at maximize the target detection probability under communication quality of service constraints, two power optimization algorithms are proposed. Finally, numerical simulations demonstrate that the sensing performance in case of unlimited backhaul capacity is much better than that in case of limited backhaul capacity. Moreover, it implied that the proposed IAPS scheme outperforms only-passive and only-active sensing schemes, especially in unlimited capacity case. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.11294v1-abstract-full').style.display = 'none'; document.getElementById('2402.11294v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.06692">arXiv:2402.06692</a> <span> [<a href="https://arxiv.org/pdf/2402.06692">pdf</a>, <a href="https://arxiv.org/format/2402.06692">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Image and Video Processing">eess.IV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Artificial Intelligence">cs.AI</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Graphics">cs.GR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Multimedia">cs.MM</span> </div> </div> <p class="title is-5 mathjax"> HistoHDR-Net: Histogram Equalization for Single LDR to HDR Image Translation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Barua%2C+H+B">Hrishav Bakul Barua</a>, <a href="/search/eess?searchtype=author&query=Krishnasamy%2C+G">Ganesh Krishnasamy</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">KokSheik Wong</a>, <a href="/search/eess?searchtype=author&query=Dhall%2C+A">Abhinav Dhall</a>, <a href="/search/eess?searchtype=author&query=Stefanov%2C+K">Kalin Stefanov</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.06692v1-abstract-short" style="display: inline;"> High Dynamic Range (HDR) imaging aims to replicate the high visual quality and clarity of real-world scenes. Due to the high costs associated with HDR imaging, the literature offers various data-driven methods for HDR image reconstruction from Low Dynamic Range (LDR) counterparts. A common limitation of these approaches is missing details in regions of the reconstructed HDR images, which are over-… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.06692v1-abstract-full').style.display = 'inline'; document.getElementById('2402.06692v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.06692v1-abstract-full" style="display: none;"> High Dynamic Range (HDR) imaging aims to replicate the high visual quality and clarity of real-world scenes. Due to the high costs associated with HDR imaging, the literature offers various data-driven methods for HDR image reconstruction from Low Dynamic Range (LDR) counterparts. A common limitation of these approaches is missing details in regions of the reconstructed HDR images, which are over- or under-exposed in the input LDR images. To this end, we propose a simple and effective method, HistoHDR-Net, to recover the fine details (e.g., color, contrast, saturation, and brightness) of HDR images via a fusion-based approach utilizing histogram-equalized LDR images along with self-attention guidance. Our experiments demonstrate the efficacy of the proposed approach over the state-of-art methods. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.06692v1-abstract-full').style.display = 'none'; document.getElementById('2402.06692v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to IEEE</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">MSC Class:</span> Artificial intelligence; Computer vision; Machine learning; Deep learning <span class="has-text-black-bis has-text-weight-semibold">ACM Class:</span> I.3.3; I.4.5 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.05722">arXiv:2402.05722</a> <span> [<a href="https://arxiv.org/pdf/2402.05722">pdf</a>, <a href="https://arxiv.org/format/2402.05722">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Information Theory">cs.IT</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> </div> </div> <p class="title is-5 mathjax"> Physical Layer Security over Fluid Antenna Systems: Secrecy Performance Analysis </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/eess?searchtype=author&query=Ghadi%2C+F+R">Farshad Rostami Ghadi</a>, <a href="/search/eess?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/eess?searchtype=author&query=Lopez-Martinez%2C+F+J">F. Javier Lopez-Martinez</a>, <a href="/search/eess?searchtype=author&query=New%2C+W+K">Wee Kiat New</a>, <a href="/search/eess?searchtype=author&query=Xu%2C+H">Hao Xu</a>, <a href="/search/eess?searchtype=author&query=Chae%2C+C">Chan-Byoung Chae</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.05722v2-abstract-short" style="display: inline;"> This paper investigates the performance of physical layer security (PLS) in fluid antenna-aided communication systems under arbitrary correlated fading channels. In particular, it is considered that a single fixed-antenna transmitter aims to send confidential information to a legitimate receiver equipped with a planar fluid antenna system (FAS), while an eavesdropper, also taking advantage of a pl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.05722v2-abstract-full').style.display = 'inline'; document.getElementById('2402.05722v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.05722v2-abstract-full" style="display: none;"> This paper investigates the performance of physical layer security (PLS) in fluid antenna-aided communication systems under arbitrary correlated fading channels. In particular, it is considered that a single fixed-antenna transmitter aims to send confidential information to a legitimate receiver equipped with a planar fluid antenna system (FAS), while an eavesdropper, also taking advantage of a planar FAS, attempts to decode the desired message. For this scenario, we first present analytical expressions of the equivalent channel distributions at the legitimate user and eavesdropper by using copula, so that the obtained analytical results are valid for any arbitrarily correlated fading distributions. Then, with the help of Gauss-Laguerre quadrature, we derive compact analytical expressions for the average secrecy capacity (ASC), the secrecy outage probability (SOP), and the secrecy energy efficiency (SEE) for the FAS wiretap channel. Moreover, for exemplary purposes, we also obtain the compact expression of ASC, SOP, and SEE by utilizing the Gaussian copula under correlated Rayleigh fading channels as a special case. Eventually, numerical results indicate that applying the fluid antenna with only one activated port to PLS can guarantee more secure and reliable transmission, when compared to traditional antenna systems (TAS) exploiting maximal ratio combining (MRC) and antenna selection (AS) under selection combining (SC). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.05722v2-abstract-full').style.display = 'none'; document.getElementById('2402.05722v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a 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