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href="/search/?searchtype=author&query=Caire%2C+G&start=200" class="pagination-link " aria-label="Page 5" aria-current="page">5 </a> </li> <li> <a href="/search/?searchtype=author&query=Caire%2C+G&start=250" class="pagination-link " aria-label="Page 6" aria-current="page">6 </a> </li> <li> <a href="/search/?searchtype=author&query=Caire%2C+G&start=300" class="pagination-link " aria-label="Page 7" aria-current="page">7 </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/2503.17088">arXiv:2503.17088</a> <span> [<a href="https://arxiv.org/pdf/2503.17088">pdf</a>, <a href="https://arxiv.org/ps/2503.17088">ps</a>, <a href="https://arxiv.org/format/2503.17088">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> </div> </div> <p class="title is-5 mathjax"> Unsourced Random Access in MIMO Quasi-Static Rayleigh Fading Channels: Finite Blocklength and Scaling Law Analyses </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Gao%2C+J">Junyuan Gao</a>, <a href="/search/cs?searchtype=author&query=Wu%2C+Y">Yongpeng Wu</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</a>, <a href="/search/cs?searchtype=author&query=Yang%2C+W">Wei Yang</a>, <a href="/search/cs?searchtype=author&query=Poor%2C+H+V">H. Vincent Poor</a>, <a href="/search/cs?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="2503.17088v1-abstract-short" style="display: inline;"> This paper considers the unsourced random access (URA) problem with a random and unknown number of active users in multiple-input multiple-output (MIMO) quasi-static Rayleigh fading channels. We derive non-asymptotic achievability bounds on the probability of incorrectly estimating the number of active users, and provide scaling laws on the gap between the estimated and true numbers of active user… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2503.17088v1-abstract-full').style.display = 'inline'; document.getElementById('2503.17088v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2503.17088v1-abstract-full" style="display: none;"> This paper considers the unsourced random access (URA) problem with a random and unknown number of active users in multiple-input multiple-output (MIMO) quasi-static Rayleigh fading channels. We derive non-asymptotic achievability bounds on the probability of incorrectly estimating the number of active users, and provide scaling laws on the gap between the estimated and true numbers of active users. We prove that the error probability reaches a plateau as the power $P$ and blocklength $n$ increase, whereas it decays exponentially with the number $L$ of receive antennas and eventually vanishes. Then, we explore the fundamental limits of URA by deriving non-asymptotic achievability bounds and converse bounds (including two single-user converse bounds and one multi-user ensemble converse bound) on the minimum energy-per-bit required by each active user to transmit $J$ bits with blocklength $n$ under misdetection and false-alarm constraints. Numerical results show that the extra required energy-per-bit due to the uncertainty in the number ${\rm{K}}_a$ of active users decreases as $L$ and $\mathbb{E}[{\rm{K}}_a]$ increase and the error requirement becomes milder. In the non-asymptotic regime, using codewords distributed on a sphere outperforms Gaussian random coding. Existing schemes are shown to exhibit a large gap to our bounds when the number of active users is large, calling for more advanced schemes that perform energy-efficiently in this case. In the asymptotic regime with $n\to\infty$, we establish scaling laws on the minimum required $P$ and $L$ to reliably support ${\rm{K}}_a$ active users as functions of $n$, which highlight the potential of MIMO in enabling low-cost communication and indicate that it is possible for the minimum required $P$ and $L$ to remain on the same order when the number of active users increases but stays below a threshold. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2503.17088v1-abstract-full').style.display = 'none'; document.getElementById('2503.17088v1-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 March, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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">Accepted by IEEE Transactions on Information Theory</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2503.04564">arXiv:2503.04564</a> <span> [<a href="https://arxiv.org/pdf/2503.04564">pdf</a>, <a href="https://arxiv.org/format/2503.04564">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="Artificial Intelligence">cs.AI</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cryptography and Security">cs.CR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Distributed, Parallel, and Cluster Computing">cs.DC</span> </div> </div> <p class="title is-5 mathjax"> Fundamental Limits of Hierarchical Secure Aggregation with Cyclic User Association </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Zhang%2C+X">Xiang Zhang</a>, <a href="/search/cs?searchtype=author&query=Li%2C+Z">Zhou Li</a>, <a href="/search/cs?searchtype=author&query=Wan%2C+K">Kai Wan</a>, <a href="/search/cs?searchtype=author&query=Sun%2C+H">Hua Sun</a>, <a href="/search/cs?searchtype=author&query=Ji%2C+M">Mingyue Ji</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2503.04564v2-abstract-short" style="display: inline;"> Secure aggregation is motivated by federated learning (FL) where a cloud server aims to compute an averaged model (i.e., weights of deep neural networks) of the locally-trained models of numerous clients, while adhering to data security requirements. Hierarchical secure aggregation (HSA) extends this concept to a three-layer network, where clustered users communicate with the server through an int… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2503.04564v2-abstract-full').style.display = 'inline'; document.getElementById('2503.04564v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2503.04564v2-abstract-full" style="display: none;"> Secure aggregation is motivated by federated learning (FL) where a cloud server aims to compute an averaged model (i.e., weights of deep neural networks) of the locally-trained models of numerous clients, while adhering to data security requirements. Hierarchical secure aggregation (HSA) extends this concept to a three-layer network, where clustered users communicate with the server through an intermediate layer of relays. In HSA, beyond conventional server security, relay security is also enforced to ensure that the relays remain oblivious to the users' inputs (an abstraction of the local models in FL). Existing study on HSA assumes that each user is associated with only one relay, limiting opportunities for coding across inter-cluster users to achieve efficient communication and key generation. In this paper, we consider HSA with a cyclic association pattern where each user is connected to $B$ consecutive relays in a wrap-around manner. We propose an efficient aggregation scheme which includes a message design for the inputs inspired by gradient coding-a well-known technique for efficient communication in distributed computing-along with a highly nontrivial security key design. We also derive novel converse bounds on the minimum achievable communication and key rates using information-theoretic arguments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2503.04564v2-abstract-full').style.display = 'none'; document.getElementById('2503.04564v2-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 March, 2025; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 March, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2025. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2503.02004">arXiv:2503.02004</a> <span> [<a href="https://arxiv.org/pdf/2503.02004">pdf</a>, <a href="https://arxiv.org/format/2503.02004">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> <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"> Group Sparsity Methods for Compressive Space-Frequency Channel Estimation and Spatial Equalization in Fluid Antenna System </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Dong%2C+X">Xuehui Dong</a>, <a href="/search/cs?searchtype=author&query=Wan%2C+K">Kai Wan</a>, <a href="/search/cs?searchtype=author&query=Li%2C+S">Shuangyang Li</a>, <a href="/search/cs?searchtype=author&query=Qiu%2C+R+C">Robert Caiming Qiu</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2503.02004v1-abstract-short" style="display: inline;"> Fluid Antenna System (FAS) unlocks unprecedented flexibility in wireless channel optimization through spatial reconfigurability. However, its practical deployment is hindered by the coupled challenges posed by high-dimensional channel estimation and real-time position optimization. This paper bridges wireless propagation physics with compressed sensing theory to address these challenges through th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2503.02004v1-abstract-full').style.display = 'inline'; document.getElementById('2503.02004v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2503.02004v1-abstract-full" style="display: none;"> Fluid Antenna System (FAS) unlocks unprecedented flexibility in wireless channel optimization through spatial reconfigurability. However, its practical deployment is hindered by the coupled challenges posed by high-dimensional channel estimation and real-time position optimization. This paper bridges wireless propagation physics with compressed sensing theory to address these challenges through three aspects. First, we establish a group-sparse recovery framework for space-frequency characteristics (SFC) in FAS, formally characterizing leakage-induced sparsity degradation from limited aperture and bandwidth as a structured group-sparsity problem. By deriving dictionary-adapted group restricted isometry property (D-GRIP), we prove tight recovery bounds for a convex $\ell_1/\ell_2$-mixed norm optimization formulation that preserves leakage-aware sparsity patterns. Second, we develop a Descending Correlation Group Orthogonal Matching Pursuit (DC-GOMP) algorithm that systematically relaxes leakage constraints to reduce subcoherence. This approach enables robust FSC recovery with accelerated convergence and superior performance compared to conventional compressive sensing methods like OMP or GOMP. Third, we formulate spatial equalization (SE) as a mixed-integer linear programming (MILP) problem, ensuring optimality through the branch-and-bound method. To achieve real-time implementability while maintaining near-optimal performance, we complement this with a greedy algorithm. Simulation results demonstrate the proposed channel estimation algorithm effectively resolves energy misallocation and enables recovery of weak details, achieving superior recovery accuracy and convergence rate. The SE framework suppresses deep fading phenomena and reduces hardware deployment overhead while maintaining equivalent link reliability. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2503.02004v1-abstract-full').style.display = 'none'; document.getElementById('2503.02004v1-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> 3 March, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2025. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2502.18251">arXiv:2502.18251</a> <span> [<a href="https://arxiv.org/pdf/2502.18251">pdf</a>, <a href="https://arxiv.org/ps/2502.18251">ps</a>, <a href="https://arxiv.org/format/2502.18251">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> </div> </div> <p class="title is-5 mathjax"> Optimal Communication-Computation Trade-off in Hierarchical Gradient Coding </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Gholami%2C+A">Ali Gholami</a>, <a href="/search/cs?searchtype=author&query=Jahani-Nezhad%2C+T">Tayyebeh Jahani-Nezhad</a>, <a href="/search/cs?searchtype=author&query=Wan%2C+K">Kai Wan</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2502.18251v1-abstract-short" style="display: inline;"> In this paper, we study gradient coding in a hierarchical setting, where there are intermediate nodes between the server and the workers. This structure reduces the bandwidth requirements at the server, which is a bottleneck in conventional gradient coding systems. In this paper, the intermediate nodes, referred to as $\textit{relays}$, process the data received from workers and send the results t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.18251v1-abstract-full').style.display = 'inline'; document.getElementById('2502.18251v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.18251v1-abstract-full" style="display: none;"> In this paper, we study gradient coding in a hierarchical setting, where there are intermediate nodes between the server and the workers. This structure reduces the bandwidth requirements at the server, which is a bottleneck in conventional gradient coding systems. In this paper, the intermediate nodes, referred to as $\textit{relays}$, process the data received from workers and send the results to the server for the final gradient computation. Our main contribution is deriving the optimal communication-computation trade-off by designing a linear coding scheme inspired by coded computing techniques, considering straggling and adversarial nodes among both relays and workers. The processing of the data in the relays makes it possible to achieve both the relay-to-server and the worker-to-relay communication loads simultaneously optimal with regard to the computation load. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.18251v1-abstract-full').style.display = 'none'; document.getElementById('2502.18251v1-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, 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">Partly submitted to ISIT 2025</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2502.09520">arXiv:2502.09520</a> <span> [<a href="https://arxiv.org/pdf/2502.09520">pdf</a>, <a href="https://arxiv.org/format/2502.09520">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"> SQ-GAN: Semantic Image Communications Using Masked Vector Quantization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Pezone%2C+F">Francesco Pezone</a>, <a href="/search/cs?searchtype=author&query=Barbarossa%2C+S">Sergio Barbarossa</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2502.09520v1-abstract-short" style="display: inline;"> This work introduces Semantically Masked VQ-GAN (SQ-GAN), a novel approach integrating generative models to optimize image compression for semantic/task-oriented communications. SQ-GAN employs off-the-shelf semantic semantic segmentation and a new specifically developed semantic-conditioned adaptive mask module (SAMM) to selectively encode semantically significant features of the images. SQ-GAN ou… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.09520v1-abstract-full').style.display = 'inline'; document.getElementById('2502.09520v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.09520v1-abstract-full" style="display: none;"> This work introduces Semantically Masked VQ-GAN (SQ-GAN), a novel approach integrating generative models to optimize image compression for semantic/task-oriented communications. SQ-GAN employs off-the-shelf semantic semantic segmentation and a new specifically developed semantic-conditioned adaptive mask module (SAMM) to selectively encode semantically significant features of the images. SQ-GAN outperforms state-of-the-art image compression schemes such as JPEG2000 and BPG across multiple metrics, including perceptual quality and semantic segmentation accuracy on the post-decoding reconstructed image, at extreme low compression rates expressed in bits per pixel. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.09520v1-abstract-full').style.display = 'none'; document.getElementById('2502.09520v1-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 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/2501.13298">arXiv:2501.13298</a> <span> [<a href="https://arxiv.org/pdf/2501.13298">pdf</a>, <a href="https://arxiv.org/format/2501.13298">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> </div> </div> <p class="title is-5 mathjax"> Collaborative Coded Caching for Partially Connected Networks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Akcay%2C+K">Kagan Akcay</a>, <a href="/search/cs?searchtype=author&query=Lampiris%2C+E">Eleftherios Lampiris</a>, <a href="/search/cs?searchtype=author&query=Salehi%2C+M">MohammadJavad Salehi</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2501.13298v2-abstract-short" style="display: inline;"> Coded caching leverages the differences in user cache memories to achieve gains that scale with the total cache size, alleviating network congestion due to high-quality content requests. Additionally, distributing transmitters over a wide area can mitigate the adverse effects of path loss. In this work, we consider a partially connected network where the channel between distributed transmitters (h… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.13298v2-abstract-full').style.display = 'inline'; document.getElementById('2501.13298v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.13298v2-abstract-full" style="display: none;"> Coded caching leverages the differences in user cache memories to achieve gains that scale with the total cache size, alleviating network congestion due to high-quality content requests. Additionally, distributing transmitters over a wide area can mitigate the adverse effects of path loss. In this work, we consider a partially connected network where the channel between distributed transmitters (helpers) and users is modeled as a distributed MIMO Gaussian broadcast channel. We propose a novel delivery scheme consisting of two phases: partitioning and transmission. In the partitioning phase, users with identical cache profiles are partitioned into the minimum number of sets, such that users within each set can successfully decode their desired message from a joint transmission enabled by MIMO precoding. To optimally partition the users, we employ the branch and bound method. In the transmission phase, each partition is treated as a single entity, and codewords are multicast to partitions with distinct cache profiles. The proposed delivery scheme is applicable to any partially connected network, and while the partitioning is optimal, the overall delivery scheme, including transmission, is heuristic. Interestingly, simulation results show that its performance closely approximates that of the fully connected optimal solution. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.13298v2-abstract-full').style.display = 'none'; document.getElementById('2501.13298v2-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 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 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/2501.12148">arXiv:2501.12148</a> <span> [<a href="https://arxiv.org/pdf/2501.12148">pdf</a>, <a href="https://arxiv.org/format/2501.12148">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> </div> </div> <p class="title is-5 mathjax"> Deep Unfolding of Fixed-Point Based Algorithm for Weighted Sum Rate Maximization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Hauffen%2C+J+C">Jan Christian Hauffen</a>, <a href="/search/cs?searchtype=author&query=Tan%2C+C+W">Chee Wei Tan</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2501.12148v2-abstract-short" style="display: inline;"> In this paper, we propose a novel approach that harnesses the standard interference function, specifically tailored to address the unique challenges of non-convex optimization in wireless networks. We begin by establishing theoretical guarantees for our method under the assumption that the interference function exhibits log-concavity. Building on this foundation, we develop a Primal-Dual Algorithm… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.12148v2-abstract-full').style.display = 'inline'; document.getElementById('2501.12148v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.12148v2-abstract-full" style="display: none;"> In this paper, we propose a novel approach that harnesses the standard interference function, specifically tailored to address the unique challenges of non-convex optimization in wireless networks. We begin by establishing theoretical guarantees for our method under the assumption that the interference function exhibits log-concavity. Building on this foundation, we develop a Primal-Dual Algorithm (PDA) to approximate the solution to the Weighted Sum Rate (WSR) maximization problem. To further enhance computational efficiency, we leverage the deep unfolding technique, significantly reducing the complexity of the proposed algorithm. Through numerical experiments, we demonstrate the competitiveness of our method compared to the state-of-the-art fractional programming benchmark, commonly referred to as FPLinQ. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.12148v2-abstract-full').style.display = 'none'; document.getElementById('2501.12148v2-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 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 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/2501.11855">arXiv:2501.11855</a> <span> [<a href="https://arxiv.org/pdf/2501.11855">pdf</a>, <a href="https://arxiv.org/format/2501.11855">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> </div> </div> <p class="title is-5 mathjax"> A New Construction Structure on Coded Caching with Linear Subpacketization: Non-Half-Sum Disjoint Packing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Cheng%2C+M">Minquan Cheng</a>, <a href="/search/cs?searchtype=author&query=Wei%2C+H">Huimei Wei</a>, <a href="/search/cs?searchtype=author&query=Wan%2C+K">Kai Wan</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2501.11855v3-abstract-short" style="display: inline;"> Coded caching is a promising technique to effectively reduce peak traffic by using local caches and the multicast gains generated by these local caches. We prefer to design a coded caching scheme with the subpacketization $F$ and transmission load $R$ as small as possible since these are the key metrics for evaluating the implementation complexity and transmission efficiency of the scheme, respect… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.11855v3-abstract-full').style.display = 'inline'; document.getElementById('2501.11855v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.11855v3-abstract-full" style="display: none;"> Coded caching is a promising technique to effectively reduce peak traffic by using local caches and the multicast gains generated by these local caches. We prefer to design a coded caching scheme with the subpacketization $F$ and transmission load $R$ as small as possible since these are the key metrics for evaluating the implementation complexity and transmission efficiency of the scheme, respectively. However, most of the existing coded caching schemes have large subpacketizations which grow exponentially with the number of users $K$, and there are a few schemes with linear subpacketizations which have large transmission loads. In this paper, we focus on studying the linear subpacketization, i.e., $K=F$, coded caching scheme with low transmission load. Specifically, we first introduce a new combinatorial structure called non-half-sum disjoint packing (NHSDP) which can be used to generate a coded caching scheme with $K=F$. Then a class of new schemes is obtained by constructing NHSDP. Theoretical and numerical comparisons show that (i) compared to the existing schemes with linear subpacketization (to the number of users), the proposed scheme achieves a lower load; (ii) compared to some existing schemes with polynomial subpacketization, the proposed scheme can also achieve a lower load in some cases; (iii) compared to some existing schemes with exponential subpacketization, the proposed scheme has loads close to those of these schemes in some cases. Moreover, the new concept of NHSDP is closely related to the classical combinatorial structures such as cyclic difference packing (CDP), non-three-term arithmetic progressions (NTAP), and perfect hash family (PHF). These connections indicate that NHSDP is an important combinatorial structure in the field of combinatorial design. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.11855v3-abstract-full').style.display = 'none'; document.getElementById('2501.11855v3-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 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 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/2501.11834">arXiv:2501.11834</a> <span> [<a href="https://arxiv.org/pdf/2501.11834">pdf</a>, <a href="https://arxiv.org/format/2501.11834">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> </div> </div> <p class="title is-5 mathjax"> PDA Construction via Union of Cartesian Product Cache Configurations for Coded Caching </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Wang%2C+J">Jinyu Wang</a>, <a href="/search/cs?searchtype=author&query=Cheng%2C+M">Minquan Cheng</a>, <a href="/search/cs?searchtype=author&query=Wan%2C+K">Kai Wan</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2501.11834v1-abstract-short" style="display: inline;"> Caching is an efficient technique to reduce peak traffic by storing popular content in local caches. Placement delivery array (PDA) proposed by Yan et al. is a combinatorial structure to design coded caching schemes with uncoded placement and one-shot linear delivery. By taking the $m$-fold Cartesian product of a small base PDA, Wang et al. constructed a big PDA while maintaining the memory ratio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.11834v1-abstract-full').style.display = 'inline'; document.getElementById('2501.11834v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.11834v1-abstract-full" style="display: none;"> Caching is an efficient technique to reduce peak traffic by storing popular content in local caches. Placement delivery array (PDA) proposed by Yan et al. is a combinatorial structure to design coded caching schemes with uncoded placement and one-shot linear delivery. By taking the $m$-fold Cartesian product of a small base PDA, Wang et al. constructed a big PDA while maintaining the memory ratio and transmission load unchanged, which achieves linear growth in both the number of users and coded caching gain. In order to achieve exponential growth in both the number of users and coded caching gain, in this paper we propose a PDA construction by taking the union operation of the cache configurations from the $m$-fold Cartesian product of a base PDA. The resulting PDA leads to a coded caching scheme with subpacketization increasing sub-exponentially with the number of users while keeping the load constant for fixed memory ratio. By applying the proposed construction to existing base PDAs, three new coded caching schemes are obtained, which cover some existing schemes as special cases and can achieve lower load with simultaneously lower subpacketization for some memory ratios. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.11834v1-abstract-full').style.display = 'none'; document.getElementById('2501.11834v1-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> 20 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">35 pages, 4 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/2501.01721">arXiv:2501.01721</a> <span> [<a href="https://arxiv.org/pdf/2501.01721">pdf</a>, <a href="https://arxiv.org/format/2501.01721">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"> Uncovering the Iceberg in the Sea: Fundamentals of Pulse Shaping and Modulation Design for Random ISAC Signals </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Liu%2C+F">Fan Liu</a>, <a href="/search/cs?searchtype=author&query=Xiong%2C+Y">Yifeng Xiong</a>, <a href="/search/cs?searchtype=author&query=Lu%2C+S">Shihang Lu</a>, <a href="/search/cs?searchtype=author&query=Li%2C+S">Shuangyang Li</a>, <a href="/search/cs?searchtype=author&query=Yuan%2C+W">Weijie Yuan</a>, <a href="/search/cs?searchtype=author&query=Masouros%2C+C">Christos Masouros</a>, <a href="/search/cs?searchtype=author&query=Jin%2C+S">Shi Jin</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2501.01721v1-abstract-short" style="display: inline;"> Integrated Sensing and Communications (ISAC) is expected to play a pivotal role in future 6G networks. To maximize time-frequency resource utilization, 6G ISAC systems must exploit data payload signals, that are inherently random, for both communication and sensing tasks. This paper provides a comprehensive analysis of the sensing performance of such communication-centric ISAC signals, with a focu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.01721v1-abstract-full').style.display = 'inline'; document.getElementById('2501.01721v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.01721v1-abstract-full" style="display: none;"> Integrated Sensing and Communications (ISAC) is expected to play a pivotal role in future 6G networks. To maximize time-frequency resource utilization, 6G ISAC systems must exploit data payload signals, that are inherently random, for both communication and sensing tasks. This paper provides a comprehensive analysis of the sensing performance of such communication-centric ISAC signals, with a focus on modulation and pulse shaping design to reshape the statistical properties of their auto-correlation functions (ACFs), thereby improving the target ranging performance. We derive a closed-form expression for the expectation of the squared ACF of random ISAC signals, considering arbitrary modulation bases and constellation mappings within the Nyquist pulse shaping framework. The structure is metaphorically described as an ``iceberg hidden in the sea", where the ``iceberg'' represents the squared mean of the ACF of random ISAC signals, that is determined by the pulse shaping filter, and the ``sea level'' characterizes the corresponding variance, caused by the randomness of the data payload. Our analysis shows that, for QAM/PSK constellations with Nyquist pulse shaping, Orthogonal Frequency Division Multiplexing (OFDM) achieves the lowest ranging sidelobe level across all lags. Building on these insights, we propose a novel Nyquist pulse shaping design to enhance the sensing performance of random ISAC signals. Numerical results validate our theoretical findings, showing that the proposed pulse shaping significantly reduces ranging sidelobes compared to conventional root-raised cosine (RRC) pulse shaping, thereby improving the ranging performance. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.01721v1-abstract-full').style.display = 'none'; document.getElementById('2501.01721v1-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> 3 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">13 pages, 7 figures, submitted to IEEE 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/2412.03956">arXiv:2412.03956</a> <span> [<a href="https://arxiv.org/pdf/2412.03956">pdf</a>, <a href="https://arxiv.org/format/2412.03956">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> </div> </div> <p class="title is-5 mathjax"> Blind and Topological Interference Managements for Bistatic Integrated Sensing and Communication </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Liu%2C+J">Jiayu Liu</a>, <a href="/search/cs?searchtype=author&query=Wan%2C+K">Kai Wan</a>, <a href="/search/cs?searchtype=author&query=Yi%2C+X">Xinping Yi</a>, <a href="/search/cs?searchtype=author&query=Qiu%2C+R+C">Robert Caiming Qiu</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2412.03956v4-abstract-short" style="display: inline;"> Integrated sensing and communication (ISAC) systems provide significant enhancements in performance and resource efficiency compared to individual sensing and communication systems, primarily attributed to the collaborative use of wireless resources, radio waveforms, and hardware platforms. This paper focuses on the bistatic ISAC systems with dispersed multi-receivers and one sensor. Compared to a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.03956v4-abstract-full').style.display = 'inline'; document.getElementById('2412.03956v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.03956v4-abstract-full" style="display: none;"> Integrated sensing and communication (ISAC) systems provide significant enhancements in performance and resource efficiency compared to individual sensing and communication systems, primarily attributed to the collaborative use of wireless resources, radio waveforms, and hardware platforms. This paper focuses on the bistatic ISAC systems with dispersed multi-receivers and one sensor. Compared to a monostatic ISAC system, the main challenge in the bistatic setting is that the information messages are unknown to the sensor and therefore they are seen as interference, while the channel between the transmitters and the sensor is unknown to the transmitters. In order to mitigate the interference at the sensor while maximizing the communication degree of freedom, we introduce two strategies, namely, blind interference alignment and topological interference management. Although well-known in the context of Gaussian interference channels, these strategies are novel in the context of bistttic ISAC. For the bistatic ISAC models with heterogeneous coherence times or with heterogeneous connectivity, the achieved ISAC tradeoff points in terms of communication and sensing degrees of freedom are characterized. In particular, we show that the new tradeoff outperforms the time-sharing between the sensing-only and the communication-only schemes. Simulation results demonstrate that the proposed schemes significantly improve the channel estimation error for the sensing task compared to treating interference as noise at the sensor. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.03956v4-abstract-full').style.display = 'none'; document.getElementById('2412.03956v4-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, 2025; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 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/2411.19248">arXiv:2411.19248</a> <span> [<a href="https://arxiv.org/pdf/2411.19248">pdf</a>, <a href="https://arxiv.org/format/2411.19248">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> </div> </div> <p class="title is-5 mathjax"> Reflecting Intelligent Surfaces-Assisted Multiple-Antenna Coded Caching </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Niu%2C+X">Xiaofan Niu</a>, <a href="/search/cs?searchtype=author&query=Cheng%2C+M">Minquan Cheng</a>, <a href="/search/cs?searchtype=author&query=Wan%2C+K">Kai Wan</a>, <a href="/search/cs?searchtype=author&query=Qiu%2C+R+C">Robert Caiming Qiu</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2411.19248v1-abstract-short" style="display: inline;"> Reconfigurable intelligent surface (RIS) has been treated as a core technique in improving wireless propagation environments for the next generation wireless communication systems. This paper proposes a new coded caching problem, referred to as Reconfigurable Intelligent Surface (RIS)-assisted multiple-antenna coded caching, which is composed of a server with multiple antennas and some single-ante… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.19248v1-abstract-full').style.display = 'inline'; document.getElementById('2411.19248v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.19248v1-abstract-full" style="display: none;"> Reconfigurable intelligent surface (RIS) has been treated as a core technique in improving wireless propagation environments for the next generation wireless communication systems. This paper proposes a new coded caching problem, referred to as Reconfigurable Intelligent Surface (RIS)-assisted multiple-antenna coded caching, which is composed of a server with multiple antennas and some single-antenna cache-aided users. Different from the existing multi-antenna coded caching problems, we introduce a passive RIS (with limited number of units) into the systems to further increase the multicast gain (i.e., degrees of freedom (DoF)) in the transmission, which is done by using RIS-assisted interference nulling. That is, by using RIS, we can `erase' any path between one transmission antenna and one receive antenna. We first propose a new RIS-assisted interference nulling approach to search for the phase-shift coefficients of RIS for the sake of interference nulling, which converges faster than the state-of-the-art algorithm. After erasing some paths in each time slot, the delivery can be divided into several non-overlapping groups including transmission antennas and users, where in each group the transmission antennas serve the contained users without suffering interference from the transmissions by other groups. The division of groups for the sake of maximizing the DoF could be formulated into a combinatorial optimization problem. We propose a grouping algorithm which can find the optimal solution with low complexity, and the corresponding coded caching scheme achieving this DoF. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.19248v1-abstract-full').style.display = 'none'; document.getElementById('2411.19248v1-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 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">The short version of this paper was presented in 2024 IEEE Information Theory Workshop, Nov. 24-28, 2024</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.00745">arXiv:2411.00745</a> <span> [<a href="https://arxiv.org/pdf/2411.00745">pdf</a>, <a href="https://arxiv.org/format/2411.00745">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Distributed, Parallel, and Cluster Computing">cs.DC</span> </div> </div> <p class="title is-5 mathjax"> Private, Augmentation-Robust and Task-Agnostic Data Valuation Approach for Data Marketplace </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Jahani-Nezhad%2C+T">Tayyebeh Jahani-Nezhad</a>, <a href="/search/cs?searchtype=author&query=Moradi%2C+P">Parsa Moradi</a>, <a href="/search/cs?searchtype=author&query=Maddah-Ali%2C+M+A">Mohammad Ali Maddah-Ali</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2411.00745v1-abstract-short" style="display: inline;"> Evaluating datasets in data marketplaces, where the buyer aim to purchase valuable data, is a critical challenge. In this paper, we introduce an innovative task-agnostic data valuation method called PriArTa which is an approach for computing the distance between the distribution of the buyer's existing dataset and the seller's dataset, allowing the buyer to determine how effectively the new data c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.00745v1-abstract-full').style.display = 'inline'; document.getElementById('2411.00745v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.00745v1-abstract-full" style="display: none;"> Evaluating datasets in data marketplaces, where the buyer aim to purchase valuable data, is a critical challenge. In this paper, we introduce an innovative task-agnostic data valuation method called PriArTa which is an approach for computing the distance between the distribution of the buyer's existing dataset and the seller's dataset, allowing the buyer to determine how effectively the new data can enhance its dataset. PriArTa is communication-efficient, enabling the buyer to evaluate datasets without needing access to the entire dataset from each seller. Instead, the buyer requests that sellers perform specific preprocessing on their data and then send back the results. Using this information and a scoring metric, the buyer can evaluate the dataset. The preprocessing is designed to allow the buyer to compute the score while preserving the privacy of each seller's dataset, mitigating the risk of information leakage before the purchase. A key feature of PriArTa is its robustness to common data transformations, ensuring consistent value assessment and reducing the risk of purchasing redundant data. The effectiveness of PriArTa is demonstrated through experiments on real-world image datasets, showing its ability to perform privacy-preserving, augmentation-robust data valuation in data marketplaces. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.00745v1-abstract-full').style.display = 'none'; document.getElementById('2411.00745v1-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">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/2410.17264">arXiv:2410.17264</a> <span> [<a href="https://arxiv.org/pdf/2410.17264">pdf</a>, <a href="https://arxiv.org/format/2410.17264">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="Machine Learning">cs.LG</span> </div> </div> <p class="title is-5 mathjax"> Radio Map Prediction from Aerial Images and Application to Coverage Optimization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Jaensch%2C+F">Fabian Jaensch</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</a>, <a href="/search/cs?searchtype=author&query=Demir%2C+B">Beg眉m Demir</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="2410.17264v1-abstract-short" style="display: inline;"> In recent years, several studies have explored deep learning algorithms to predict large-scale signal fading, or path loss, in urban communication networks. The goal is to replace costly measurement campaigns, inaccurate statistical models, or computationally expensive ray-tracing simulations with machine learning models that deliver quick and accurate predictions. We focus on predicting path loss… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.17264v1-abstract-full').style.display = 'inline'; document.getElementById('2410.17264v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.17264v1-abstract-full" style="display: none;"> In recent years, several studies have explored deep learning algorithms to predict large-scale signal fading, or path loss, in urban communication networks. The goal is to replace costly measurement campaigns, inaccurate statistical models, or computationally expensive ray-tracing simulations with machine learning models that deliver quick and accurate predictions. We focus on predicting path loss radio maps using convolutional neural networks, leveraging aerial images alone or in combination with supplementary height information. Notably, our approach does not rely on explicit classification of environmental objects, which is often unavailable for most locations worldwide. While the prediction of radio maps using complete 3D environmental data is well-studied, the use of only aerial images remains under-explored. We address this gap by showing that state-of-the-art models developed for existing radio map datasets can be effectively adapted to this task, achieving strong performance. Additionally, we introduce a new model that slightly exceeds the performance of the present state-of-the-art with reduced complexity. The trained models are differentiable, and therefore they can be incorporated in various network optimization algorithms. While an extensive discussion is beyond this paper's scope, we demonstrate this through an example optimizing the directivity of base stations in cellular networks via backpropagation to enhance coverage. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.17264v1-abstract-full').style.display = 'none'; document.getElementById('2410.17264v1-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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, 8 Figures, This work has been submitted to the IEEE for possible publication. arXiv admin note: substantial text overlap with arXiv:2402.00878</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.16140">arXiv:2410.16140</a> <span> [<a href="https://arxiv.org/pdf/2410.16140">pdf</a>, <a href="https://arxiv.org/format/2410.16140">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"> Cooperative Multistatic Target Detection in Cell-Free Communication Networks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Yang%2C+T">Tianyu Yang</a>, <a href="/search/cs?searchtype=author&query=Li%2C+S">Shuangyang Li</a>, <a href="/search/cs?searchtype=author&query=Song%2C+Y">Yi Song</a>, <a href="/search/cs?searchtype=author&query=Zhi%2C+K">Kangda Zhi</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2410.16140v1-abstract-short" style="display: inline;"> In this work, we consider the target detection problem in a multistatic integrated sensing and communication (ISAC) scenario characterized by the cell-free MIMO communication network deployment, where multiple radio units (RUs) in the network cooperate with each other for the sensing task. By exploiting the angle resolution from multiple arrays deployed in the network and the delay resolution from… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16140v1-abstract-full').style.display = 'inline'; document.getElementById('2410.16140v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.16140v1-abstract-full" style="display: none;"> In this work, we consider the target detection problem in a multistatic integrated sensing and communication (ISAC) scenario characterized by the cell-free MIMO communication network deployment, where multiple radio units (RUs) in the network cooperate with each other for the sensing task. By exploiting the angle resolution from multiple arrays deployed in the network and the delay resolution from the communication signals, i.e., orthogonal frequency division multiplexing (OFDM) signals, we formulate a cooperative sensing problem with coherent data fusion of multiple RUs' observations and propose a sparse Bayesian learning (SBL)-based method, where the global coordinates of target locations are directly detected. Intensive numerical results indicate promising target detection performance of the proposed SBL-based method. Additionally, a theoretical analysis of the considered cooperative multistatic sensing task is provided using the pairwise error probability (PEP) analysis, which can be used to provide design insights, e.g., illumination and beam patterns, for the considered problem. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16140v1-abstract-full').style.display = 'none'; document.getElementById('2410.16140v1-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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 WCNC 2025</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.16104">arXiv:2410.16104</a> <span> [<a href="https://arxiv.org/pdf/2410.16104">pdf</a>, <a href="https://arxiv.org/format/2410.16104">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 Deep Unfolding-Based Scalarization Approach for Power Control in D2D Networks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Hauffen%2C+J+C">Jan Christian Hauffen</a>, <a href="/search/cs?searchtype=author&query=Jung%2C+P">Peter Jung</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2410.16104v1-abstract-short" style="display: inline;"> Optimizing network utility in device-to-device networks is typically formulated as a non-convex optimization problem. This paper addresses the scenario where the optimization variables are from a bounded but continuous set, allowing each device to perform power control. The power at each link is optimized to maximize a desired network utility. Specifically, we consider the weighted-sum-rate. The s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16104v1-abstract-full').style.display = 'inline'; document.getElementById('2410.16104v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.16104v1-abstract-full" style="display: none;"> Optimizing network utility in device-to-device networks is typically formulated as a non-convex optimization problem. This paper addresses the scenario where the optimization variables are from a bounded but continuous set, allowing each device to perform power control. The power at each link is optimized to maximize a desired network utility. Specifically, we consider the weighted-sum-rate. The state of the art benchmark for this problem is fractional programming with quadratic transform, known as FPLinQ. We propose a scalarization approach to transform the weighted-sum-rate, developing an iterative algorithm that depends on step sizes, a reference, and a direction vector. By employing the deep unfolding approach, we optimize these parameters by presenting the iterative algorithm as a finite sequence of steps, enabling it to be trained as a deep neural network. Numerical experiments demonstrate that the unfolded algorithm performs comparably to the benchmark in most cases while exhibiting lower complexity. Furthermore, the unfolded algorithm shows strong generalizability in terms of varying the number of users, the signal-to-noise ratio and arbitrary weights. The weighted-sum-rate maximizer can be integrated into a low-complexity fairness scheduler, updating priority weights via virtual queues and Lyapunov Drift Plus Penalty. This is demonstrated through experiments using proportional and max-min fairness. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16104v1-abstract-full').style.display = 'none'; document.getElementById('2410.16104v1-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.14035">arXiv:2410.14035</a> <span> [<a href="https://arxiv.org/pdf/2410.14035">pdf</a>, <a href="https://arxiv.org/format/2410.14035">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> </div> </div> <p class="title is-5 mathjax"> Optimal Communication and Key Rate Region for Hierarchical Secure Aggregation with User Collusion </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Zhang%2C+X">Xiang Zhang</a>, <a href="/search/cs?searchtype=author&query=Wan%2C+K">Kai Wan</a>, <a href="/search/cs?searchtype=author&query=Sun%2C+H">Hua Sun</a>, <a href="/search/cs?searchtype=author&query=Wang%2C+S">Shiqiang Wang</a>, <a href="/search/cs?searchtype=author&query=Ji%2C+M">Mingyue Ji</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2410.14035v5-abstract-short" style="display: inline;"> Secure aggregation is concerned with the task of securely uploading the inputs of multiple users to an aggregation server without letting the server know the inputs beyond their summation. It finds broad applications in distributed machine learning paradigms such as federated learning (FL) where multiple clients, each having access to a proprietary dataset, periodically upload their locally traine… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.14035v5-abstract-full').style.display = 'inline'; document.getElementById('2410.14035v5-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.14035v5-abstract-full" style="display: none;"> Secure aggregation is concerned with the task of securely uploading the inputs of multiple users to an aggregation server without letting the server know the inputs beyond their summation. It finds broad applications in distributed machine learning paradigms such as federated learning (FL) where multiple clients, each having access to a proprietary dataset, periodically upload their locally trained models (abstracted as inputs) to a parameter server which then generates an aggregate (e.g., averaged) model that is sent back to the clients as an initializing point for a new round of local training. To enhance the data privacy of the clients, secure aggregation protocols are developed using techniques from cryptography to ensure that the server infers no more information of the users' inputs beyond the desired aggregated input, even if the server can collude with some users. Although laying the ground for understanding the fundamental utility-security trade-off in secure aggregation, the simple star client-server architecture cannot capture more complex network architectures used in practical systems. Motivated by hierarchical federated learning, we investigate the secure aggregation problem in a $3$-layer hierarchical network consisting of clustered users connecting to an aggregation server through an intermediate layer of relays. Besides the conventional server security which requires that the server learns nothing beyond the desired sum of inputs, relay security is also imposed so that the relays infer nothing about the users' inputs and remain oblivious. For such a hierarchical secure aggregation (HSA) problem, we characterize the optimal multifaceted trade-off between communication (in terms of user-to-relay and relay-to-server communication rates) and secret key generation efficiency (in terms of individual key and source key rates). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.14035v5-abstract-full').style.display = 'none'; document.getElementById('2410.14035v5-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> 19 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.13021">arXiv:2410.13021</a> <span> [<a href="https://arxiv.org/pdf/2410.13021">pdf</a>, <a href="https://arxiv.org/format/2410.13021">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> </div> </div> <p class="title is-5 mathjax"> Multi-Source Approximate Message Passing with Random Semi-Unitary Dictionaries </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=%C3%87akmak%2C+B">Burak 脟akmak</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2410.13021v2-abstract-short" style="display: inline;"> Motivated by the recent interest in approximate message passing (AMP) for matrix-valued linear observations with superposition of \emph{multiple statistically asymmetric signal sources}, we introduce a multi-source AMP framework in which the dictionary matrices associated with each signal source are drawn from a \emph{random semi-unitary ensemble} (rather than the standard Gaussian matrix ensemble… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.13021v2-abstract-full').style.display = 'inline'; document.getElementById('2410.13021v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.13021v2-abstract-full" style="display: none;"> Motivated by the recent interest in approximate message passing (AMP) for matrix-valued linear observations with superposition of \emph{multiple statistically asymmetric signal sources}, we introduce a multi-source AMP framework in which the dictionary matrices associated with each signal source are drawn from a \emph{random semi-unitary ensemble} (rather than the standard Gaussian matrix ensemble.) While a similar model has been explored by Vehkaper{盲}, Kabashima, and Chatterjee (2016) using the replica method, here we present an AMP algorithm and provide a high-dimensional yet \emph{finite-sample} analysis. As a proof of concept, we show the effectiveness of the proposed approach on the problem of \emph{message detection and channel estimation} in an unsourced random access scenario in wireless communication. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.13021v2-abstract-full').style.display = 'none'; document.getElementById('2410.13021v2-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 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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, 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/2410.05007">arXiv:2410.05007</a> <span> [<a href="https://arxiv.org/pdf/2410.05007">pdf</a>, <a href="https://arxiv.org/format/2410.05007">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> </div> </div> <p class="title is-5 mathjax"> A Semantic Model for Physical Layer Deception </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Han%2C+B">Bin Han</a>, <a href="/search/cs?searchtype=author&query=Zhu%2C+Y">Yao Zhu</a>, <a href="/search/cs?searchtype=author&query=Schmeink%2C+A">Anke Schmeink</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</a>, <a href="/search/cs?searchtype=author&query=Schotten%2C+H+D">Hans D. Schotten</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="2410.05007v1-abstract-short" style="display: inline;"> Physical layer deception (PLD) is a novel security mechanism that combines physical layer security (PLS) with deception technologies to actively defend against eavesdroppers. In this paper, we establish a novel semantic model for PLD that evaluates its performance in terms of semantic distortion. By analyzing semantic distortion at varying levels of knowledge on the receiver's part regarding the k… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.05007v1-abstract-full').style.display = 'inline'; document.getElementById('2410.05007v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.05007v1-abstract-full" style="display: none;"> Physical layer deception (PLD) is a novel security mechanism that combines physical layer security (PLS) with deception technologies to actively defend against eavesdroppers. In this paper, we establish a novel semantic model for PLD that evaluates its performance in terms of semantic distortion. By analyzing semantic distortion at varying levels of knowledge on the receiver's part regarding the key, we derive the receiver's optimal decryption strategy, and consequently, the transmitter's optimal deception strategy. The proposed semantic model provides a more generic understanding of the PLD approach independent from coding or multiplexing schemes, and allows for efficient real-time adaptation to fading channels. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.05007v1-abstract-full').style.display = 'none'; document.getElementById('2410.05007v1-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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 ICC 2025</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.00698">arXiv:2410.00698</a> <span> [<a href="https://arxiv.org/pdf/2410.00698">pdf</a>, <a href="https://arxiv.org/ps/2410.00698">ps</a>, <a href="https://arxiv.org/format/2410.00698">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"> Analysis of Cross-Domain Message Passing for OTFS Transmissions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Chong%2C+R">Ruoxi Chong</a>, <a href="/search/cs?searchtype=author&query=Li%2C+S">Shuangyang Li</a>, <a href="/search/cs?searchtype=author&query=Wei%2C+Z">Zhiqiang Wei</a>, <a href="/search/cs?searchtype=author&query=Matthaiou%2C+M">Michail Matthaiou</a>, <a href="/search/cs?searchtype=author&query=Ng%2C+D+W+K">Derrick Wing Kwan Ng</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2410.00698v1-abstract-short" style="display: inline;"> In this paper, we investigate the performance of the cross-domain iterative detection (CDID) framework with orthogonal time frequency space (OTFS) modulation, where two distinct CDID algorithms are presented. The proposed schemes estimate/detect the information symbols iteratively across the frequency domain and the delay-Doppler (DD) domain via passing either the a posteriori or extrinsic informa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.00698v1-abstract-full').style.display = 'inline'; document.getElementById('2410.00698v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.00698v1-abstract-full" style="display: none;"> In this paper, we investigate the performance of the cross-domain iterative detection (CDID) framework with orthogonal time frequency space (OTFS) modulation, where two distinct CDID algorithms are presented. The proposed schemes estimate/detect the information symbols iteratively across the frequency domain and the delay-Doppler (DD) domain via passing either the a posteriori or extrinsic information. Building upon this framework, we investigate the error performance by considering the bias evolution and state evolution. Furthermore, we discuss their error performance in convergence and the DD domain error state lower bounds in each iteration. Specifically, we demonstrate that in convergence, the ultimate error performance of the CDID passing the a posteriori information can be characterized by two potential convergence points. In contrast, the ultimate error performance of the CDID passing the extrinsic information has only one convergence point, which, interestingly, aligns with the matched filter bound. Our numerical results confirm our analytical findings and unveil the promising error performance achieved by the proposed designs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.00698v1-abstract-full').style.display = 'none'; document.getElementById('2410.00698v1-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.08045">arXiv:2408.08045</a> <span> [<a href="https://arxiv.org/pdf/2408.08045">pdf</a>, <a href="https://arxiv.org/format/2408.08045">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> </div> </div> <p class="title is-5 mathjax"> Joint Message Detection, Channel, and User Position Estimation for Unsourced Random Access in Cell-Free Networks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Gkiouzepi%2C+E">Eleni Gkiouzepi</a>, <a href="/search/cs?searchtype=author&query=%C3%87akmak%2C+B">Burak 脟akmak</a>, <a href="/search/cs?searchtype=author&query=Opper%2C+M">Manfred Opper</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2408.08045v1-abstract-short" style="display: inline;"> We consider unsourced random access (uRA) in user-centric cell-free (CF) wireless networks, where random access users send codewords from a common codebook during specifically dedicated random access channel (RACH) slots. The system is conceptually similar to the so-called 2-step RACH currently discussed in 3GPP standardization. In order to cope with the distributed and CF nature of the network, w… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.08045v1-abstract-full').style.display = 'inline'; document.getElementById('2408.08045v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.08045v1-abstract-full" style="display: none;"> We consider unsourced random access (uRA) in user-centric cell-free (CF) wireless networks, where random access users send codewords from a common codebook during specifically dedicated random access channel (RACH) slots. The system is conceptually similar to the so-called 2-step RACH currently discussed in 3GPP standardization. In order to cope with the distributed and CF nature of the network, we propose to partition the network coverage area into zones (referred to as ''locations'') and assign an uRA codebook to each location, such that users in a certain location make use of the associated codebook. The centralized uRA decoder makes use of the multisource AMP algorithm recently proposed by the authors. This yields at once the list of active uRA codewords, an estimate of the corresponding channel vectors, and an estimate of the active users' position. We show excellent performance of this approach and perfect agreement with the rigorous theoretical ''state evolution'' analysis. We also show that the proposed ''location-based'' partitioned codebook approach significantly outperforms a baseline system with a single non-partitioned uRA codebook. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.08045v1-abstract-full').style.display = 'none'; document.getElementById('2408.08045v1-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 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">5 pages, 7 figures, to be published in 25th IEEE International Workshop on Signal Processing Advances in Wireless Communications (SPAWC)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.08954">arXiv:2407.08954</a> <span> [<a href="https://arxiv.org/pdf/2407.08954">pdf</a>, <a href="https://arxiv.org/format/2407.08954">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Cryptography and Security">cs.CR</span> </div> </div> <p class="title is-5 mathjax"> PriRoAgg: Achieving Robust Model Aggregation with Minimum Privacy Leakage for Federated Learning </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Hou%2C+S">Sizai Hou</a>, <a href="/search/cs?searchtype=author&query=Li%2C+S">Songze Li</a>, <a href="/search/cs?searchtype=author&query=Jahani-Nezhad%2C+T">Tayyebeh Jahani-Nezhad</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2407.08954v1-abstract-short" style="display: inline;"> Federated learning (FL) has recently gained significant momentum due to its potential to leverage large-scale distributed user data while preserving user privacy. However, the typical paradigm of FL faces challenges of both privacy and robustness: the transmitted model updates can potentially leak sensitive user information, and the lack of central control of the local training process leaves the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.08954v1-abstract-full').style.display = 'inline'; document.getElementById('2407.08954v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.08954v1-abstract-full" style="display: none;"> Federated learning (FL) has recently gained significant momentum due to its potential to leverage large-scale distributed user data while preserving user privacy. However, the typical paradigm of FL faces challenges of both privacy and robustness: the transmitted model updates can potentially leak sensitive user information, and the lack of central control of the local training process leaves the global model susceptible to malicious manipulations on model updates. Current solutions attempting to address both problems under the one-server FL setting fall short in the following aspects: 1) designed for simple validity checks that are insufficient against advanced attacks (e.g., checking norm of individual update); and 2) partial privacy leakage for more complicated robust aggregation algorithms (e.g., distances between model updates are leaked for multi-Krum). In this work, we formalize a novel security notion of aggregated privacy that characterizes the minimum amount of user information, in the form of some aggregated statistics of users' updates, that is necessary to be revealed to accomplish more advanced robust aggregation. We develop a general framework PriRoAgg, utilizing Lagrange coded computing and distributed zero-knowledge proof, to execute a wide range of robust aggregation algorithms while satisfying aggregated privacy. As concrete instantiations of PriRoAgg, we construct two secure and robust protocols based on state-of-the-art robust algorithms, for which we provide full theoretical analyses on security and complexity. Extensive experiments are conducted for these protocols, demonstrating their robustness against various model integrity attacks, and their efficiency advantages over baselines. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.08954v1-abstract-full').style.display = 'none'; document.getElementById('2407.08954v1-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> 11 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/2407.06691">arXiv:2407.06691</a> <span> [<a href="https://arxiv.org/pdf/2407.06691">pdf</a>, <a href="https://arxiv.org/ps/2407.06691">ps</a>, <a href="https://arxiv.org/format/2407.06691">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"> OFDM Achieves the Lowest Ranging Sidelobe Under Random ISAC Signaling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Liu%2C+F">Fan Liu</a>, <a href="/search/cs?searchtype=author&query=Zhang%2C+Y">Ying Zhang</a>, <a href="/search/cs?searchtype=author&query=Xiong%2C+Y">Yifeng Xiong</a>, <a href="/search/cs?searchtype=author&query=Li%2C+S">Shuangyang Li</a>, <a href="/search/cs?searchtype=author&query=Yuan%2C+W">Weijie Yuan</a>, <a href="/search/cs?searchtype=author&query=Gao%2C+F">Feifei Gao</a>, <a href="/search/cs?searchtype=author&query=Jin%2C+S">Shi Jin</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2407.06691v2-abstract-short" style="display: inline;"> This paper aims to answer a fundamental question in the area of Integrated Sensing and Communications (ISAC): What is the optimal communication-centric ISAC waveform for ranging? Towards that end, we first established a generic framework to analyze the sensing performance of communication-centric ISAC waveforms built upon orthonormal signaling bases and random data symbols. Then, we evaluated thei… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06691v2-abstract-full').style.display = 'inline'; document.getElementById('2407.06691v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.06691v2-abstract-full" style="display: none;"> This paper aims to answer a fundamental question in the area of Integrated Sensing and Communications (ISAC): What is the optimal communication-centric ISAC waveform for ranging? Towards that end, we first established a generic framework to analyze the sensing performance of communication-centric ISAC waveforms built upon orthonormal signaling bases and random data symbols. Then, we evaluated their ranging performance by adopting both the periodic and aperiodic auto-correlation functions (P-ACF and A-ACF), and defined the expectation of the integrated sidelobe level (EISL) as a sensing performance metric. On top of that, we proved that among all communication waveforms with cyclic prefix (CP), the orthogonal frequency division multiplexing (OFDM) modulation is the only globally optimal waveform that achieves the lowest ranging sidelobe for quadrature amplitude modulation (QAM) and phase shift keying (PSK) constellations, in terms of both the EISL and the sidelobe level at each individual lag of the P-ACF. As a step forward, we proved that among all communication waveforms without CP, OFDM is a locally optimal waveform for QAM/PSK in the sense that it achieves a local minimum of the EISL of the A-ACF. Finally, we demonstrated by numerical results that under QAM/PSK constellations, there is no other orthogonal communication-centric waveform that achieves a lower ranging sidelobe level than that of the OFDM, in terms of both P-ACF and A-ACF cases. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06691v2-abstract-full').style.display = 'none'; document.getElementById('2407.06691v2-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 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">16 pages, 11 figures, submitted to IEEE 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/2407.02877">arXiv:2407.02877</a> <span> [<a href="https://arxiv.org/pdf/2407.02877">pdf</a>, <a href="https://arxiv.org/format/2407.02877">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"> Resource Allocation Design for Next-Generation Multiple Access: A Tutorial Overview </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Wei%2C+Z">Zhiqiang Wei</a>, <a href="/search/cs?searchtype=author&query=Xu%2C+D">Dongfang Xu</a>, <a href="/search/cs?searchtype=author&query=Li%2C+S">Shuangyang Li</a>, <a href="/search/cs?searchtype=author&query=Song%2C+S">Shenghui Song</a>, <a href="/search/cs?searchtype=author&query=Ng%2C+D+W+K">Derrick Wing Kwan Ng</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2407.02877v1-abstract-short" style="display: inline;"> Multiple access is the cornerstone technology for each generation of wireless cellular networks and resource allocation design plays a crucial role in multiple access. In this paper, we present a comprehensive tutorial overview for junior researchers in this field, aiming to offer a foundational guide for resource allocation design in the context of next-generation multiple access (NGMA). Initiall… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02877v1-abstract-full').style.display = 'inline'; document.getElementById('2407.02877v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.02877v1-abstract-full" style="display: none;"> Multiple access is the cornerstone technology for each generation of wireless cellular networks and resource allocation design plays a crucial role in multiple access. In this paper, we present a comprehensive tutorial overview for junior researchers in this field, aiming to offer a foundational guide for resource allocation design in the context of next-generation multiple access (NGMA). Initially, we identify three types of channels in future wireless cellular networks over which NGMA will be implemented, namely: natural channels, reconfigurable channels, and functional channels. Natural channels are traditional uplink and downlink communication channels; reconfigurable channels are defined as channels that can be proactively reshaped via emerging platforms or techniques, such as intelligent reflecting surface (IRS), unmanned aerial vehicle (UAV), and movable/fluid antenna (M/FA); and functional channels support not only communication but also other functionalities simultaneously, with typical examples including integrated sensing and communication (ISAC) and joint computing and communication (JCAC) channels. Then, we introduce NGMA models applicable to these three types of channels that cover most of the practical communication scenarios of future wireless communications. Subsequently, we articulate the key optimization technical challenges inherent in the resource allocation design for NGMA, categorizing them into rate-oriented, power-oriented, and reliability-oriented resource allocation designs. The corresponding optimization approaches for solving the formulated resource allocation design problems are then presented. Finally, simulation results are presented and discussed to elucidate the practical implications and insights derived from resource allocation designs in NGMA. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02877v1-abstract-full').style.display = 'none'; document.getElementById('2407.02877v1-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> 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">69 pages, 10 figures, 5 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.02442">arXiv:2407.02442</a> <span> [<a href="https://arxiv.org/pdf/2407.02442">pdf</a>, <a href="https://arxiv.org/format/2407.02442">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> </div> </div> <p class="title is-5 mathjax"> A New Achievable Region of the $K$-User MAC Wiretap Channel with Confidential and Open Messages Under Strong Secrecy </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Xu%2C+H">Hao Xu</a>, <a href="/search/cs?searchtype=author&query=Wong%2C+K">Kai-Kit Wong</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2407.02442v1-abstract-short" style="display: inline;"> This paper investigates the achievable region of a $K$-user discrete memoryless (DM) multiple access wiretap (MAC-WT) channel, where each user transmits both secret and open messages. All these messages are intended for Bob, while Eve is only interested in the secret messages. In the achievable coding strategy, the confidential information is protected by open messages and also by the introduction… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02442v1-abstract-full').style.display = 'inline'; document.getElementById('2407.02442v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.02442v1-abstract-full" style="display: none;"> This paper investigates the achievable region of a $K$-user discrete memoryless (DM) multiple access wiretap (MAC-WT) channel, where each user transmits both secret and open messages. All these messages are intended for Bob, while Eve is only interested in the secret messages. In the achievable coding strategy, the confidential information is protected by open messages and also by the introduction of auxiliary messages. When introducing an auxiliary message, one has to ensure that, on one hand, its rate is large enough for protecting the secret message from Eve and, on the other hand, the resulting sum rate (together with the secret and open message rate) does not exceed Bob's decoding capability. This yields an inequality structure involving the rates of all users' secret, open, and auxiliary messages. To obtain the rate region, the auxiliary message rates must be eliminated from the system of inequalities. A direct application of the Fourier-Motzkin elimination procedure is elusive since a) it requires that the number of users $K$ is explicitly given, and b) even for small $K = 3, 4, \ldots$, the number of inequalities becomes extremely large. We prove the result for general $K$ through the combined use of Fourier-Motzkin elimination procedure and mathematical induction. This paper adopts the strong secrecy metric, characterized by information leakage. To prove the achievability under this criterion, we analyze the resolvability region of a $K$-user DM-MAC channel. In addition, we show that users with zero secrecy rate can play different roles and use different strategies in encoding their messages. These strategies yield non-redundant rate inequalities. By considering all possible coding strategies, we provide a new achievable region for the considered channel, and show that it strictly improves those already known in the existing literature by considering a specific example. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02442v1-abstract-full').style.display = 'none'; document.getElementById('2407.02442v1-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">61 pages, 15 figures. arXiv admin note: text overlap with arXiv:2209.05403</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.01336">arXiv:2407.01336</a> <span> [<a href="https://arxiv.org/pdf/2407.01336">pdf</a>, <a href="https://arxiv.org/format/2407.01336">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"> Compressed Sensing Inspired User Acquisition for Downlink Integrated Sensing and Communication Transmissions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Song%2C+Y">Yi Song</a>, <a href="/search/cs?searchtype=author&query=Pedraza%2C+F">Fernando Pedraza</a>, <a href="/search/cs?searchtype=author&query=Li%2C+S">Shuangyang Li</a>, <a href="/search/cs?searchtype=author&query=Li%2C+S">Siyao Li</a>, <a href="/search/cs?searchtype=author&query=Yu%2C+H">Han Yu</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2407.01336v1-abstract-short" style="display: inline;"> This paper investigates radar-assisted user acquisition for downlink multi-user multiple-input multiple-output (MIMO) transmission using Orthogonal Frequency Division Multiplexing (OFDM) signals. Specifically, we formulate a concise mathematical model for the user acquisition problem, where each user is characterized by its delay and beamspace response. Therefore, we propose a two-stage method for… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.01336v1-abstract-full').style.display = 'inline'; document.getElementById('2407.01336v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.01336v1-abstract-full" style="display: none;"> This paper investigates radar-assisted user acquisition for downlink multi-user multiple-input multiple-output (MIMO) transmission using Orthogonal Frequency Division Multiplexing (OFDM) signals. Specifically, we formulate a concise mathematical model for the user acquisition problem, where each user is characterized by its delay and beamspace response. Therefore, we propose a two-stage method for user acquisition, where the Multiple Signal Classification (MUSIC) algorithm is adopted for delay estimation, and then a least absolute shrinkage and selection operator (LASSO) is applied for estimating the user response in the beamspace. Furthermore, we also provide a comprehensive performance analysis of the considered problem based on the pair-wise error probability (PEP). Particularly, we show that the rank and the geometric mean of non-zero eigenvalues of the squared beamspace difference matrix determines the user acquisition performance. More importantly, we reveal that simultaneously probing multiple beams outperforms concentrating power on a specific beam direction in each time slot under the power constraint, when only limited OFDM symbols are transmitted. Our numerical results confirm our conclusions and also demonstrate a promising acquisition performance of the proposed two-stage method. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.01336v1-abstract-full').style.display = 'none'; document.getElementById('2407.01336v1-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 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/2407.00750">arXiv:2407.00750</a> <span> [<a href="https://arxiv.org/pdf/2407.00750">pdf</a>, <a href="https://arxiv.org/format/2407.00750">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Cryptography and Security">cs.CR</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"> Physical Layer Deception with Non-Orthogonal Multiplexing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Chen%2C+W">Wenwen Chen</a>, <a href="/search/cs?searchtype=author&query=Han%2C+B">Bin Han</a>, <a href="/search/cs?searchtype=author&query=Zhu%2C+Y">Yao Zhu</a>, <a href="/search/cs?searchtype=author&query=Schmeink%2C+A">Anke Schmeink</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</a>, <a href="/search/cs?searchtype=author&query=Schotten%2C+H+D">Hans D. Schotten</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="2407.00750v3-abstract-short" style="display: inline;"> Physical layer security (PLS) is a promising technology to secure wireless communications by exploiting the physical properties of the wireless channel. However, the passive nature of PLS creates a significant imbalance between the effort required by eavesdroppers and legitimate users to secure data. To address this imbalance, in this article, we propose a novel framework of physical layer decepti… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.00750v3-abstract-full').style.display = 'inline'; document.getElementById('2407.00750v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.00750v3-abstract-full" style="display: none;"> Physical layer security (PLS) is a promising technology to secure wireless communications by exploiting the physical properties of the wireless channel. However, the passive nature of PLS creates a significant imbalance between the effort required by eavesdroppers and legitimate users to secure data. To address this imbalance, in this article, we propose a novel framework of physical layer deception (PLD), which combines PLS with deception technologies to actively counteract wiretapping attempts. Combining a two-stage encoder with randomized ciphering and non-orthogonal multiplexing, the PLD approach enables the wireless communication system to proactively counter eavesdroppers with deceptive messages. Relying solely on the superiority of the legitimate channel over the eavesdropping channel, the PLD framework can effectively protect the confidentiality of the transmitted messages, even against eavesdroppers who possess knowledge equivalent to that of the legitimate receiver. We prove the validity of the PLD framework with in-depth analyses and demonstrate its superiority over conventional PLS approaches with comprehensive numerical benchmarks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.00750v3-abstract-full').style.display = 'none'; document.getElementById('2407.00750v3-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 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 June, 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">Accepted for publication in 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/2405.00572">arXiv:2405.00572</a> <span> [<a href="https://arxiv.org/pdf/2405.00572">pdf</a>, <a href="https://arxiv.org/format/2405.00572">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Systems and Control">eess.SY</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/SPAWC60668.2024.10694442">10.1109/SPAWC60668.2024.10694442 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Modular Pragmatic Architecture for Multiuser MIMO with Array-Fed RIS </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Tiwari%2C+K+K">Krishan Kumar Tiwari</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2405.00572v2-abstract-short" style="display: inline;"> We propose a power- and hardware-efficient, pragmatic, modular, multiuser/multibeam array-fed RIS architecture particularly suited to operate in very high frequency bands (high mmWave and sub-THz), where channels are typically sparse in the beamspace and line-of-sight (LOS) is required to achieve an acceptable received signal level. The key module is an active multi-antenna feeder (AMAF) with a sm… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.00572v2-abstract-full').style.display = 'inline'; document.getElementById('2405.00572v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.00572v2-abstract-full" style="display: none;"> We propose a power- and hardware-efficient, pragmatic, modular, multiuser/multibeam array-fed RIS architecture particularly suited to operate in very high frequency bands (high mmWave and sub-THz), where channels are typically sparse in the beamspace and line-of-sight (LOS) is required to achieve an acceptable received signal level. The key module is an active multi-antenna feeder (AMAF) with a small number of active antennas placed in the near field of a RIS with a much larger number of passive controllable reflecting elements. We propose a pragmatic approach to obtain a steerable beam with high gain and very low sidelobes. Then, $K$ independently controlled beams can be achieved by stacking $K$ of such AMAF-RIS modules. Our analysis takes in full account: 1) the near-end crosstalk (NEXT) between the modules, 2) the far-end crosstalk (FEXT) due to the sidelobes; 3) a thorough energy efficiency comparison with respect to conventional active arrays with the same beamforming performance. Overall, we show that the proposed architecture is very attractive in terms of spectral efficiency, ease of implementation (hardware complexity), and energy efficiency. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.00572v2-abstract-full').style.display = 'none'; document.getElementById('2405.00572v2-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 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 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, 8 figures, The 25th IEEE International Workshop on Signal Processing Advances in Wireless Communications (SPAWC) 2024, Lucca, Italy. This paper is a condensed version of our earlier work (arXiv:2311.18593), focusing specifically on the example of a 16x16 RIS fed by a 2x2 AMAF presented at SPAWC 2024. For a more comprehensive treatment, including log scale ground footprints, RIS phase heat maps, frequency selectivity analysis for broadband design, beam steering-based codebook design, zero forcing precoding, benchmark comparisons against optimum active arrays, multiple examples, and detailed power efficiency analysis, please refer to the full version in arXiv:2311.18593.</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.09198">arXiv:2404.09198</a> <span> [<a href="https://arxiv.org/pdf/2404.09198">pdf</a>, <a href="https://arxiv.org/ps/2404.09198">ps</a>, <a href="https://arxiv.org/format/2404.09198">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> </div> </div> <p class="title is-5 mathjax"> Unsourced Random Access in MIMO Quasi-Static Rayleigh Fading Channels with Finite Blocklength </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Gao%2C+J">Junyuan Gao</a>, <a href="/search/cs?searchtype=author&query=Wu%2C+Y">Yongpeng Wu</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</a>, <a href="/search/cs?searchtype=author&query=Yang%2C+W">Wei Yang</a>, <a href="/search/cs?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="2404.09198v1-abstract-short" style="display: inline;"> This paper explores the fundamental limits of unsourced random access (URA) with a random and unknown number ${\rm{K}}_a$ of active users in MIMO quasi-static Rayleigh fading channels. First, we derive an upper bound on the probability of incorrectly estimating the number of active users. We prove that it exponentially decays with the number of receive antennas and eventually vanishes, whereas rea… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.09198v1-abstract-full').style.display = 'inline'; document.getElementById('2404.09198v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.09198v1-abstract-full" style="display: none;"> This paper explores the fundamental limits of unsourced random access (URA) with a random and unknown number ${\rm{K}}_a$ of active users in MIMO quasi-static Rayleigh fading channels. First, we derive an upper bound on the probability of incorrectly estimating the number of active users. We prove that it exponentially decays with the number of receive antennas and eventually vanishes, whereas reaches a plateau as the power and blocklength increase. Then, we derive non-asymptotic achievability and converse bounds on the minimum energy-per-bit required by each active user to reliably transmit $J$ bits with blocklength $n$. Numerical results verify the tightness of our bounds, suggesting that they provide benchmarks to evaluate existing schemes. The extra required energy-per-bit due to the uncertainty of the number of active users decreases as $\mathbb{E}[{\rm{K}}_a]$ increases. Compared to random access with individual codebooks, the URA paradigm achieves higher spectral and energy efficiency. Moreover, using codewords distributed on a sphere is shown to outperform the Gaussian random coding scheme in the non-asymptotic regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.09198v1-abstract-full').style.display = 'none'; document.getElementById('2404.09198v1-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 April, 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">Accepted by ISIT 2024</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.14192">arXiv:2403.14192</a> <span> [<a href="https://arxiv.org/pdf/2403.14192">pdf</a>, <a href="https://arxiv.org/ps/2403.14192">ps</a>, <a href="https://arxiv.org/format/2403.14192">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"> Fundamentals of Delay-Doppler Communications: Practical Implementation and Extensions to OTFS </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Li%2C+S">Shuangyang Li</a>, <a href="/search/cs?searchtype=author&query=Jung%2C+P">Peter Jung</a>, <a href="/search/cs?searchtype=author&query=Yuan%2C+W">Weijie Yuan</a>, <a href="/search/cs?searchtype=author&query=Wei%2C+Z">Zhiqiang Wei</a>, <a href="/search/cs?searchtype=author&query=Yuan%2C+J">Jinhong Yuan</a>, <a href="/search/cs?searchtype=author&query=Bai%2C+B">Baoming Bai</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2403.14192v1-abstract-short" style="display: inline;"> The recently proposed orthogonal time frequency space (OTFS) modulation, which is a typical Delay-Doppler (DD) communication scheme, has attracted significant attention thanks to its appealing performance over doubly-selective channels. In this paper, we present the fundamentals of general DD communications from the viewpoint of the Zak transform. We start our study by constructing DD domain basis… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.14192v1-abstract-full').style.display = 'inline'; document.getElementById('2403.14192v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.14192v1-abstract-full" style="display: none;"> The recently proposed orthogonal time frequency space (OTFS) modulation, which is a typical Delay-Doppler (DD) communication scheme, has attracted significant attention thanks to its appealing performance over doubly-selective channels. In this paper, we present the fundamentals of general DD communications from the viewpoint of the Zak transform. We start our study by constructing DD domain basis functions aligning with the time-frequency (TF)-consistency condition, which are globally quasi-periodic and locally twisted-shifted. We unveil that these features are translated to unique signal structures in both time and frequency, which are beneficial for communication purposes. Then, we focus on the practical implementations of DD Nyquist communications, where we show that rectangular windows achieve perfect DD orthogonality, while truncated periodic signals can obtain sufficient DD orthogonality. Particularly, smoothed rectangular window with excess bandwidth can result in a slightly worse orthogonality but better pulse localization in the DD domain. Furthermore, we present a practical pulse shaping framework for general DD communications and derive the corresponding input-output relation under various shaping pulses. Our numerical results agree with our derivations and also demonstrate advantages of DD communications over conventional orthogonal frequency-division multiplexing (OFDM). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.14192v1-abstract-full').style.display = 'none'; document.getElementById('2403.14192v1-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 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/2403.01558">arXiv:2403.01558</a> <span> [<a href="https://arxiv.org/pdf/2403.01558">pdf</a>, <a href="https://arxiv.org/format/2403.01558">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> </div> </div> <p class="title is-5 mathjax"> Adapt or Wait: Quality Adaptation for Cache-aided Channels </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Lampiris%2C+E">Eleftherios Lampiris</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2403.01558v1-abstract-short" style="display: inline;"> This work focuses on quality adaptation as a means to counter the effects of channel degradation in wireless, cache-aided channels. We design a delivery scheme which combines coded caching, superposition coding, and scalable source coding, while keeping the caching scheme oblivious to channel qualities. By properly adjusting the quality at the degraded users we are able to satisfy all demands in a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.01558v1-abstract-full').style.display = 'inline'; document.getElementById('2403.01558v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.01558v1-abstract-full" style="display: none;"> This work focuses on quality adaptation as a means to counter the effects of channel degradation in wireless, cache-aided channels. We design a delivery scheme which combines coded caching, superposition coding, and scalable source coding, while keeping the caching scheme oblivious to channel qualities. By properly adjusting the quality at the degraded users we are able to satisfy all demands in a time-efficient manner. In addition, superposition coding allows us to serve high-rate users with high content quality without subjecting them to a delay penalty caused by users with lower rate channels. We design a communication framework that covers all possible channel rate and quality configurations and we further provide algorithms that can optimise the served quality. An interesting outcome of this work is that a modest quality reduction at the degraded users can counter the effects of significant channel degradation. For example, in a 100-user system with normalized cache size 1/10 at each user, if 10 users experience channel degradation of 60% compared to the rate of the non-degraded users, we show that our transmission strategy leads to a 85% quality at the degraded users and perfect quality at the non-degraded users. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.01558v1-abstract-full').style.display = 'none'; document.getElementById('2403.01558v1-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> 3 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 Transactions on 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/2402.00878">arXiv:2402.00878</a> <span> [<a href="https://arxiv.org/pdf/2402.00878">pdf</a>, <a href="https://arxiv.org/format/2402.00878">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="Machine Learning">cs.LG</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"> Radio Map Estimation -- An Open Dataset with Directive Transmitter Antennas and Initial Experiments </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Jaensch%2C+F">Fabian Jaensch</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</a>, <a href="/search/cs?searchtype=author&query=Demir%2C+B">Beg眉m Demir</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="2402.00878v1-abstract-short" style="display: inline;"> Over the last years, several works have explored the application of deep learning algorithms to determine the large-scale signal fading (also referred to as ``path loss'') between transmitter and receiver pairs in urban communication networks. The central idea is to replace costly measurement campaigns, inaccurate statistical models or computationally expensive ray-tracing simulations by machine l… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.00878v1-abstract-full').style.display = 'inline'; document.getElementById('2402.00878v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.00878v1-abstract-full" style="display: none;"> Over the last years, several works have explored the application of deep learning algorithms to determine the large-scale signal fading (also referred to as ``path loss'') between transmitter and receiver pairs in urban communication networks. The central idea is to replace costly measurement campaigns, inaccurate statistical models or computationally expensive ray-tracing simulations by machine learning models which, once trained, produce accurate predictions almost instantly. Although the topic has attracted attention from many researchers, there are few open benchmark datasets and codebases that would allow everyone to test and compare the developed methods and algorithms. We take a step towards filling this gap by releasing a publicly available dataset of simulated path loss radio maps together with realistic city maps from real-world locations and aerial images from open datasources. Initial experiments regarding model architectures, input feature design and estimation of radio maps from aerial images are presented and the code is made available. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.00878v1-abstract-full').style.display = 'none'; document.getElementById('2402.00878v1-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, 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">13 pages, 121 figures, This work has been submitted to the IEEE 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/2401.06669">arXiv:2401.06669</a> <span> [<a href="https://arxiv.org/pdf/2401.06669">pdf</a>, <a href="https://arxiv.org/format/2401.06669">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"> User-Centric Cell-Free Wireless Networks for 6G: Communication Theoretic Models and Research Challenges </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=G%C3%B6ttsch%2C+F">Fabian G枚ttsch</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</a>, <a href="/search/cs?searchtype=author&query=Xu%2C+W">Wen Xu</a>, <a href="/search/cs?searchtype=author&query=Schubert%2C+M">Martin Schubert</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="2401.06669v1-abstract-short" style="display: inline;"> This paper presents a comprehensive communication theoretic model for the physical layer of a cell-free user-centric network, formed by user equipments (UEs), radio units (RUs), and decentralized units (DUs), uniformly spatially distributed over a given coverage area. We consider RUs equipped with multiple antennas, and focus on the regime where the UE, RU, and DU densities are constant and theref… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.06669v1-abstract-full').style.display = 'inline'; document.getElementById('2401.06669v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.06669v1-abstract-full" style="display: none;"> This paper presents a comprehensive communication theoretic model for the physical layer of a cell-free user-centric network, formed by user equipments (UEs), radio units (RUs), and decentralized units (DUs), uniformly spatially distributed over a given coverage area. We consider RUs equipped with multiple antennas, and focus on the regime where the UE, RU, and DU densities are constant and therefore the number of such nodes grows with the coverage area. A system is said scalable if the computing load and information rate at any node in the network converges to a constant as the network size (coverage area) grows to infinity. This imposes that each UE must be processed by a (user-centric) finite-size cluster of RUs, and that such cluster processors are dynamically allocated to the DUs (e.g., as software defined virtual network functions) in order to achieve a balanced computation load. We also assume that the RUs are connected to the DUs through a packet switching network, in order to achieve adaptive routing and load balance. For this model, we define in details the dynamic cluster formation and uplink pilot allocation. As a consequence of the pilot allocation and the scalability constraint, each cluster processor has a partial view of the network channel state information. We define the condition of ``ideal partial CSI'' when the channel vectors that can be estimated are perfectly known (while the ones that cannot be estimated are not know at all). We develop two attractive cluster-based linear receiver schemes for the uplink, and an uplink-downlink duality that allows to reuse such vectors as precoders for the downlink. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.06669v1-abstract-full').style.display = 'none'; document.getElementById('2401.06669v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.03898">arXiv:2401.03898</a> <span> [<a href="https://arxiv.org/pdf/2401.03898">pdf</a>, <a href="https://arxiv.org/format/2401.03898">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"> Ultra-Dense Cell-Free Massive MIMO for 6G: Technical Overview and Open Questions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Ngo%2C+H+Q">Hien Quoc Ngo</a>, <a href="/search/cs?searchtype=author&query=Interdonato%2C+G">Giovanni Interdonato</a>, <a href="/search/cs?searchtype=author&query=Larsson%2C+E+G">Erik G. Larsson</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</a>, <a href="/search/cs?searchtype=author&query=Andrews%2C+J+G">Jeffrey G. Andrews</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="2401.03898v3-abstract-short" style="display: inline;"> Ultra-dense cell-free massive multiple-input multiple-output (CF-MMIMO) has emerged as a promising technology expected to meet the future ubiquitous connectivity requirements and ever-growing data traffic demands in 6G. This article provides a contemporary overview of ultra-dense CF-MMIMO networks, and addresses important unresolved questions on their future deployment. We first present a comprehe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.03898v3-abstract-full').style.display = 'inline'; document.getElementById('2401.03898v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.03898v3-abstract-full" style="display: none;"> Ultra-dense cell-free massive multiple-input multiple-output (CF-MMIMO) has emerged as a promising technology expected to meet the future ubiquitous connectivity requirements and ever-growing data traffic demands in 6G. This article provides a contemporary overview of ultra-dense CF-MMIMO networks, and addresses important unresolved questions on their future deployment. We first present a comprehensive survey of state-of-the-art research on CF-MMIMO and ultra-dense networks. Then, we discuss the key challenges of CF-MMIMO under ultra-dense scenarios such as low-complexity architecture and processing, low-complexity/scalable resource allocation, fronthaul limitation, massive access, synchronization, and channel acquisition. Finally, we answer key open questions, considering different design comparisons and discussing suitable methods dealing with the key challenges of ultra-dense CF-MMIMO. The discussion aims to provide a valuable roadmap for interesting future research directions in this area, facilitating the development of CF-MMIMO MIMO for 6G. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.03898v3-abstract-full').style.display = 'none'; document.getElementById('2401.03898v3-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 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">Proceedings of the IEEE, accepted</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.02595">arXiv:2312.02595</a> <span> [<a href="https://arxiv.org/pdf/2312.02595">pdf</a>, <a href="https://arxiv.org/format/2312.02595">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> </div> </div> <p class="title is-5 mathjax"> Optimal Fairness Scheduling for Coded Caching in Multi-AP Multi-antenna WLAN </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Akcay%2C+K">Kagan Akcay</a>, <a href="/search/cs?searchtype=author&query=Salehi%2C+M">MohammadJavad Salehi</a>, <a href="/search/cs?searchtype=author&query=T%C3%B6lli%2C+A">Antti T枚lli</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2312.02595v2-abstract-short" style="display: inline;"> Coded caching (CC) schemes exploit the cumulative cache memory of network users, outperforming traditional uncoded schemes where cache contents are only used locally. Interestingly, this CC gain can also be combined with the spatial multiplexing gain of multi-antenna transmissions. In this paper, we extend the existing results of CC-aided data delivery in multi-access point (AP) wireless local are… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.02595v2-abstract-full').style.display = 'inline'; document.getElementById('2312.02595v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.02595v2-abstract-full" style="display: none;"> Coded caching (CC) schemes exploit the cumulative cache memory of network users, outperforming traditional uncoded schemes where cache contents are only used locally. Interestingly, this CC gain can also be combined with the spatial multiplexing gain of multi-antenna transmissions. In this paper, we extend the existing results of CC-aided data delivery in multi-access point (AP) wireless local area networks (WLAN) and video streaming applications by assuming multi-antenna transmitters at AP nodes. We present two distinct methods for using the extra resource that multi-antenna transmitters provide. While the first method tries to reduce the number of interference links in the network graph, the second one aims to remove inter-stream interference so that users with similar cache contents can be served simultaneously. While both methods provide increased throughput, they differ significantly in the underlying concept. Numerical simulations are used to compare the performance of different methods. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.02595v2-abstract-full').style.display = 'none'; document.getElementById('2312.02595v2-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 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.18593">arXiv:2311.18593</a> <span> [<a href="https://arxiv.org/pdf/2311.18593">pdf</a>, <a href="https://arxiv.org/format/2311.18593">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 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/10.36227/techrxiv.24570445.v2">10.36227/techrxiv.24570445.v2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A New Old Idea: Beam-Steering Reflectarrays for Efficient Sub-THz Multiuser MIMO </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Tiwari%2C+K+K">Krishan Kumar Tiwari</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2311.18593v2-abstract-short" style="display: inline;"> We present a novel, power- & hardware-efficient, multiuser, multibeam RIS (Reflective Intelligent Surface) architecture for multiuser MIMO, especially for very high frequency bands (e.g., high mmWave and sub-THz), where channels are typically sparse in the beamspace and LOS is the dominant component. The key module is formed by an active multiantenna feeder (AMAF) with a small number of active ant… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.18593v2-abstract-full').style.display = 'inline'; document.getElementById('2311.18593v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.18593v2-abstract-full" style="display: none;"> We present a novel, power- & hardware-efficient, multiuser, multibeam RIS (Reflective Intelligent Surface) architecture for multiuser MIMO, especially for very high frequency bands (e.g., high mmWave and sub-THz), where channels are typically sparse in the beamspace and LOS is the dominant component. The key module is formed by an active multiantenna feeder (AMAF) with a small number of active antennas, placed in the near field of a RIS with a much larger number of passive controllable reflecting elements. We propose a pragmatic approach to obtain a steerable beam with high gain and very low sidelobes. Then K independently controlled beams can be achieved by closely stacking K such AMAF-RIS modules. Our analysis includes the mutual interference between the modules and the fact that, due to the delay difference of propagation through the AMAF-RIS structure, the resulting channel matrix is frequency selective even for pure LOS propagation. We consider a 3D geometry and show that "beam focusing" is in fact possible (and much more effective in terms of coverage) also in the far-field, by creating spotbeams with limited footprint both in angle and in range. Our results show that: 1) simple RF beamforming (BF) without computationally expensive baseband multiuser precoding is sufficient to practically eliminate multiuser interference when the users are chosen with sufficient angular/range separation, thanks to the extremely low sidelobe beams; 2) the impact of beam pointing errors with standard deviation as large as 2.5 deg and RIS quantized phase-shifters with quantization bits > 2 is essentially negligible; 3) The proposed architecture is more power efficient & much simpler from a hardware implementation viewpoint than standard active arrays with the same BF performance. We show also that the array gain of the proposed AMAF-RIS structure is linear with the RIS aperture. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.18593v2-abstract-full').style.display = 'none'; document.getElementById('2311.18593v2-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </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/2310.20239">arXiv:2310.20239</a> <span> [<a href="https://arxiv.org/pdf/2310.20239">pdf</a>, <a href="https://arxiv.org/format/2310.20239">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> </div> </div> <p class="title is-5 mathjax"> Coded Caching Schemes for Multiaccess Topologies via Combinatorial Design </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Cheng%2C+M">Minquan Cheng</a>, <a href="/search/cs?searchtype=author&query=Wan%2C+K">Kai Wan</a>, <a href="/search/cs?searchtype=author&query=Elia%2C+P">Petros Elia</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2310.20239v1-abstract-short" style="display: inline;"> This paper studies a multiaccess coded caching (MACC) where the connectivity topology between the users and the caches can be described by a class of combinatorial designs. Our model includes as special cases several MACC topologies considered in previous works. The considered MACC network includes a server containing $N$ files, $螕$ cache nodes and $K$ cacheless users, where each user can access… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.20239v1-abstract-full').style.display = 'inline'; document.getElementById('2310.20239v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.20239v1-abstract-full" style="display: none;"> This paper studies a multiaccess coded caching (MACC) where the connectivity topology between the users and the caches can be described by a class of combinatorial designs. Our model includes as special cases several MACC topologies considered in previous works. The considered MACC network includes a server containing $N$ files, $螕$ cache nodes and $K$ cacheless users, where each user can access $L$ cache nodes. The server is connected to the users via an error-free shared link, while the users can retrieve the cache content of the connected cache-nodes while the users can directly access the content in their connected cache-nodes. Our goal is to minimise the worst-case transmission load on the shared link in the delivery phase. The main limitation of the existing MACC works is that only some specific access topologies are considered, and thus the number of users $K$ should be either linear or exponential to $螕$. We overcome this limitation by formulating a new access topology derived from two classical combinatorial structures, referred to as the $t$-design and the $t$-group divisible design. In these topologies, $K$ scales linearly, polynomially, or even exponentially with $螕$. By leveraging the properties of the considered combinatorial structures, we propose two classes of coded caching schemes for a flexible number of users, where the number of users can scale linearly, polynomially or exponentially with the number of cache nodes. In addition, our schemes can unify most schemes for the shared link network and unify many schemes for the multi-access network except for the cyclic wrap-around topology. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.20239v1-abstract-full').style.display = 'none'; document.getElementById('2310.20239v1-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 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </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">48 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/2310.15737">arXiv:2310.15737</a> <span> [<a href="https://arxiv.org/pdf/2310.15737">pdf</a>, <a href="https://arxiv.org/format/2310.15737">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> </div> </div> <p class="title is-5 mathjax"> Semantic-Preserving Image Coding based on Conditional Diffusion Models </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Pezone%2C+F">Francesco Pezone</a>, <a href="/search/cs?searchtype=author&query=Musa%2C+O">Osman Musa</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</a>, <a href="/search/cs?searchtype=author&query=Barbarossa%2C+S">Sergio Barbarossa</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="2310.15737v2-abstract-short" style="display: inline;"> Semantic communication, rather than on a bit-by-bit recovery of the transmitted messages, focuses on the meaning and the goal of the communication itself. In this paper, we propose a novel semantic image coding scheme that preserves the semantic content of an image, while ensuring a good trade-off between coding rate and image quality. The proposed Semantic-Preserving Image Coding based on Conditi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.15737v2-abstract-full').style.display = 'inline'; document.getElementById('2310.15737v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.15737v2-abstract-full" style="display: none;"> Semantic communication, rather than on a bit-by-bit recovery of the transmitted messages, focuses on the meaning and the goal of the communication itself. In this paper, we propose a novel semantic image coding scheme that preserves the semantic content of an image, while ensuring a good trade-off between coding rate and image quality. The proposed Semantic-Preserving Image Coding based on Conditional Diffusion Models (SPIC) transmitter encodes a Semantic Segmentation Map (SSM) and a low-resolution version of the image to be transmitted. The receiver then reconstructs a high-resolution image using a Denoising Diffusion Probabilistic Models (DDPM) doubly conditioned to the SSM and the low-resolution image. As shown by the numerical examples, compared to state-of-the-art (SOTA) approaches, the proposed SPIC exhibits a better balance between the conventional rate-distortion trade-off and the preservation of semantically-relevant features. Code available at https://github.com/frapez1/SPIC <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.15737v2-abstract-full').style.display = 'none'; document.getElementById('2310.15737v2-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </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">Accepted at ICASSP 2024</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.14911">arXiv:2310.14911</a> <span> [<a href="https://arxiv.org/pdf/2310.14911">pdf</a>, <a href="https://arxiv.org/format/2310.14911">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> </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/TWC.2024.3409609">10.1109/TWC.2024.3409609 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Joint Fronthaul Load Balancing and Computation Resource Allocation in Cell-Free User-Centric Massive MIMO Networks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Li%2C+Z">Zhiyang Li</a>, <a href="/search/cs?searchtype=author&query=G%C3%B6ttsch%2C+F">Fabian G枚ttsch</a>, <a href="/search/cs?searchtype=author&query=Li%2C+S">Siyao Li</a>, <a href="/search/cs?searchtype=author&query=Chen%2C+M">Ming Chen</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2310.14911v2-abstract-short" style="display: inline;"> We consider scalable cell-free massive multiple-input multiple-output networks under an open radio access network paradigm comprising user equipments (UEs), radio units (RUs), and decentralized processing units (DUs). UEs are served by dynamically allocated user-centric clusters of RUs. The corresponding cluster processors (implementing the physical layer for each user) are hosted by the DUs as so… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.14911v2-abstract-full').style.display = 'inline'; document.getElementById('2310.14911v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.14911v2-abstract-full" style="display: none;"> We consider scalable cell-free massive multiple-input multiple-output networks under an open radio access network paradigm comprising user equipments (UEs), radio units (RUs), and decentralized processing units (DUs). UEs are served by dynamically allocated user-centric clusters of RUs. The corresponding cluster processors (implementing the physical layer for each user) are hosted by the DUs as software-defined virtual network functions. Unlike the current literature, mainly focused on the characterization of the user rates under unrestricted fronthaul communication and computation, in this work we explicitly take into account the fronthaul topology, the limited fronthaul communication capacity, and computation constraints at the DUs. In particular, we systematically address the new problem of joint fronthaul load balancing and allocation of the computation resource. As a consequence of our new optimization framework, we present representative numerical results highlighting the existence of an optimal number of quantization bits in the analog-to-digital conversion at the RUs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.14911v2-abstract-full').style.display = 'none'; document.getElementById('2310.14911v2-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 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </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">15 pages, 7 figures, accepted to be published in 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/2310.09889">arXiv:2310.09889</a> <span> [<a href="https://arxiv.org/pdf/2310.09889">pdf</a>, <a href="https://arxiv.org/format/2310.09889">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> </div> </div> <p class="title is-5 mathjax"> The Capacity Region of Information Theoretic Secure Aggregation with Uncoded Groupwise Keys </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Wan%2C+K">Kai Wan</a>, <a href="/search/cs?searchtype=author&query=Sun%2C+H">Hua Sun</a>, <a href="/search/cs?searchtype=author&query=Ji%2C+M">Mingyue Ji</a>, <a href="/search/cs?searchtype=author&query=Mi%2C+T">Tiebin Mi</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2310.09889v2-abstract-short" style="display: inline;"> This paper considers the secure aggregation problem for federated learning under an information theoretic cryptographic formulation, where distributed training nodes (referred to as users) train models based on their own local data and a curious-but-honest server aggregates the trained models without retrieving other information about users' local data. Secure aggregation generally contains two ph… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.09889v2-abstract-full').style.display = 'inline'; document.getElementById('2310.09889v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.09889v2-abstract-full" style="display: none;"> This paper considers the secure aggregation problem for federated learning under an information theoretic cryptographic formulation, where distributed training nodes (referred to as users) train models based on their own local data and a curious-but-honest server aggregates the trained models without retrieving other information about users' local data. Secure aggregation generally contains two phases, namely key sharing phase and model aggregation phase. Due to the common effect of user dropouts in federated learning, the model aggregation phase should contain two rounds, where in the first round the users transmit masked models and, in the second round, according to the identity of surviving users after the first round, these surviving users transmit some further messages to help the server decrypt the sum of users' trained models. The objective of the considered information theoretic formulation is to characterize the capacity region of the communication rates in the two rounds from the users to the server in the model aggregation phase, assuming that key sharing has already been performed offline in prior. In this context, Zhao and Sun completely characterized the capacity region under the assumption that the keys can be arbitrary random variables. More recently, an additional constraint, known as "uncoded groupwise keys," has been introduced. This constraint entails the presence of multiple independent keys within the system, with each key being shared by precisely S users. The capacity region for the information-theoretic secure aggregation problem with uncoded groupwise keys was established in our recent work subject to the condition S > K - U, where K is the number of total users and U is the designed minimum number of surviving users. In this paper we fully characterize of the the capacity region for this problem by proposing a new converse bound and an achievable scheme. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.09889v2-abstract-full').style.display = 'none'; document.getElementById('2310.09889v2-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 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </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">37 pages, 3 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/2310.09749">arXiv:2310.09749</a> <span> [<a href="https://arxiv.org/pdf/2310.09749">pdf</a>, <a href="https://arxiv.org/format/2310.09749">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> </div> </div> <p class="title is-5 mathjax"> From Torch to Projector: Fundamental Tradeoff of Integrated Sensing and Communications </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Xiong%2C+Y">Yifeng Xiong</a>, <a href="/search/cs?searchtype=author&query=Liu%2C+F">Fan Liu</a>, <a href="/search/cs?searchtype=author&query=Wan%2C+K">Kai Wan</a>, <a href="/search/cs?searchtype=author&query=Yuan%2C+W">Weijie Yuan</a>, <a href="/search/cs?searchtype=author&query=Cui%2C+Y">Yuanhao Cui</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2310.09749v2-abstract-short" style="display: inline;"> Sensing and communications (S&C) have been historically developed in parallel. In recent decade, they have been evolving from separation to integration, giving rise to the integrated sensing and communications (ISAC) paradigm, that has been recognized as one of the six key 6G usage scenarios. Despite the plethora of research works dedicated to ISAC signal processing, the fundamental performance li… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.09749v2-abstract-full').style.display = 'inline'; document.getElementById('2310.09749v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.09749v2-abstract-full" style="display: none;"> Sensing and communications (S&C) have been historically developed in parallel. In recent decade, they have been evolving from separation to integration, giving rise to the integrated sensing and communications (ISAC) paradigm, that has been recognized as one of the six key 6G usage scenarios. Despite the plethora of research works dedicated to ISAC signal processing, the fundamental performance limits of S&C remain widely unexplored in an ISAC system. In this tutorial paper, we attempt to summarize the recent research findings in characterizing the performance boundary of ISAC systems and the resulting S&C tradeoff from an information-theoretical viewpoint. We begin with a folklore "torch metaphor" that depicts the resource competition mechanism of S&C. Then, we elaborate on the fundamental capacity-distortion (C-D) theory, indicating the incompleteness of this metaphor. Towards that end, we further elaborate on the S&C tradeoff by discussing a special case within the C-D framework, namely the Cramer-Rao bound (CRB)-rate region. In particular, S&C have preference discrepancies over both the subspace occupied by the transmitted signal and the adopted codebook, leading to a "projector metaphor" complementary to the ISAC torch analogy. We also present two practical design examples by leveraging the lessons learned from fundamental theories. Finally, we conclude the paper by identifying a number of open challenges. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.09749v2-abstract-full').style.display = 'none'; document.getElementById('2310.09749v2-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 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </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">15 pages, 11 figures, submitted to IEEE BITS the Information Theory Magazine</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.07658">arXiv:2310.07658</a> <span> [<a href="https://arxiv.org/pdf/2310.07658">pdf</a>, <a href="https://arxiv.org/format/2310.07658">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="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Networking and Internet Architecture">cs.NI</span> </div> </div> <p class="title is-5 mathjax"> The First Pathloss Radio Map Prediction Challenge </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Yapar%2C+%C3%87">脟a臒kan Yapar</a>, <a href="/search/cs?searchtype=author&query=Jaensch%2C+F">Fabian Jaensch</a>, <a href="/search/cs?searchtype=author&query=Levie%2C+R">Ron Levie</a>, <a href="/search/cs?searchtype=author&query=Kutyniok%2C+G">Gitta Kutyniok</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2310.07658v1-abstract-short" style="display: inline;"> To foster research and facilitate fair comparisons among recently proposed pathloss radio map prediction methods, we have launched the ICASSP 2023 First Pathloss Radio Map Prediction Challenge. In this short overview paper, we briefly describe the pathloss prediction problem, the provided datasets, the challenge task and the challenge evaluation methodology. Finally, we present the results of the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.07658v1-abstract-full').style.display = 'inline'; document.getElementById('2310.07658v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.07658v1-abstract-full" style="display: none;"> To foster research and facilitate fair comparisons among recently proposed pathloss radio map prediction methods, we have launched the ICASSP 2023 First Pathloss Radio Map Prediction Challenge. In this short overview paper, we briefly describe the pathloss prediction problem, the provided datasets, the challenge task and the challenge evaluation methodology. Finally, we present the results of the challenge. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.07658v1-abstract-full').style.display = 'none'; document.getElementById('2310.07658v1-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> 11 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </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">ICASSP 2023</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.14778">arXiv:2309.14778</a> <span> [<a href="https://arxiv.org/pdf/2309.14778">pdf</a>, <a href="https://arxiv.org/format/2309.14778">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="Emerging Technologies">cs.ET</span> </div> </div> <p class="title is-5 mathjax"> Multi-static Parameter Estimation in the Near/Far Field Beam Space for Integrated Sensing and Communication Applications </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Dehkordi%2C+S+K">Saeid K. Dehkordi</a>, <a href="/search/cs?searchtype=author&query=Pucci%2C+L">Lorenzo Pucci</a>, <a href="/search/cs?searchtype=author&query=Jung%2C+P">Peter Jung</a>, <a href="/search/cs?searchtype=author&query=Giorgetti%2C+A">Andrea Giorgetti</a>, <a href="/search/cs?searchtype=author&query=Paolini%2C+E">Enrico Paolini</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2309.14778v1-abstract-short" style="display: inline;"> This work proposes a maximum likelihood (ML)-based parameter estimation framework for a millimeter wave (mmWave) integrated sensing and communication (ISAC) system in a multi-static configuration using energy-efficient hybrid digital-analog arrays. Due to the typically large arrays deployed in the higher frequency bands to mitigate isotropic path loss, such arrays may operate in the near-field reg… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.14778v1-abstract-full').style.display = 'inline'; document.getElementById('2309.14778v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.14778v1-abstract-full" style="display: none;"> This work proposes a maximum likelihood (ML)-based parameter estimation framework for a millimeter wave (mmWave) integrated sensing and communication (ISAC) system in a multi-static configuration using energy-efficient hybrid digital-analog arrays. Due to the typically large arrays deployed in the higher frequency bands to mitigate isotropic path loss, such arrays may operate in the near-field regime. The proposed parameter estimation in this work consists of a two-stage estimation process, where the first stage is based on far-field assumptions, and is used to obtain a first estimate of the target parameters. In cases where the target is determined to be in the near-field of the arrays, a second estimation based on near-field assumptions is carried out to obtain more accurate estimates. In particular, we select beamfocusing array weights designed to achieve a constant gain over an extended spatial region and re-estimate the target parameters at the receivers. We evaluate the effectiveness of the proposed framework in numerous scenarios through numerical simulations and demonstrate the impact of the custom-designed flat-gain beamfocusing codewords in increasing the communication performance of the system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.14778v1-abstract-full').style.display = 'none'; document.getElementById('2309.14778v1-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 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2023. </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">16 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/2308.02324">arXiv:2308.02324</a> <span> [<a href="https://arxiv.org/pdf/2308.02324">pdf</a>, <a href="https://arxiv.org/format/2308.02324">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"> Robust mmWave/sub-THz multi-connectivity using minimal coordination and coarse synchronization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Miretti%2C+L">Lorenzo Miretti</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</a>, <a href="/search/cs?searchtype=author&query=Sta%C5%84czak%2C+S">S艂awomir Sta艅czak</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="2308.02324v3-abstract-short" style="display: inline;"> This study investigates simpler alternatives to coherent joint transmission for supporting robust connectivity against signal blockage in mmWave/sub-THz access networks. By taking an information-theoretic viewpoint, we demonstrate analytically that with a careful design, full macrodiversity gains and significant SNR gains can be achieved through canonical receivers and minimal coordination and syn… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.02324v3-abstract-full').style.display = 'inline'; document.getElementById('2308.02324v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.02324v3-abstract-full" style="display: none;"> This study investigates simpler alternatives to coherent joint transmission for supporting robust connectivity against signal blockage in mmWave/sub-THz access networks. By taking an information-theoretic viewpoint, we demonstrate analytically that with a careful design, full macrodiversity gains and significant SNR gains can be achieved through canonical receivers and minimal coordination and synchronization requirements at the infrastructure side. Our proposed scheme extends non-coherent joint transmission by employing a special form of diversity to counteract artificially induced deep fades that would otherwise make this technique often compare unfavorably against standard transmitter selection schemes. Additionally, the inclusion of an Alamouti-like space-time coding layer is shown to recover a significant fraction of the optimal performance. Our conclusions are based on a statistical single-user multi-point intermittent block fading channel model that, although simplified, enables rigorous ergodic and outage rate analysis, while also considering timing offsets due to imperfect delay compensation. In addition, we validate our theoretical approach by means of deterministic ray-tracing simulations that capture the essential features of next generation mmWave/sub-THz communications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.02324v3-abstract-full').style.display = 'none'; document.getElementById('2308.02324v3-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 4 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </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">Accepted version</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.01760">arXiv:2307.01760</a> <span> [<a href="https://arxiv.org/pdf/2307.01760">pdf</a>, <a href="https://arxiv.org/format/2307.01760">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 with MOCZ Waveform </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Dehkordi%2C+S+K">Saeid K. Dehkordi</a>, <a href="/search/cs?searchtype=author&query=Jung%2C+P">Peter Jung</a>, <a href="/search/cs?searchtype=author&query=Walk%2C+P">Philipp Walk</a>, <a href="/search/cs?searchtype=author&query=Wieruch%2C+D">Dennis Wieruch</a>, <a href="/search/cs?searchtype=author&query=Heuermann%2C+K">Kai Heuermann</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2307.01760v1-abstract-short" style="display: inline;"> In this work, we propose a waveform based on Modulation on Conjugate-reciprocal Zeros (MOCZ) originally proposed for short-packet communications in [1], as a new Integrated Sensing and Communication (ISAC) waveform. Having previously established the key advantages of MOCZ for noncoherent and sporadic communication, here we leverage the optimal auto-correlation property of Binary MOCZ (BMOCZ) for s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.01760v1-abstract-full').style.display = 'inline'; document.getElementById('2307.01760v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.01760v1-abstract-full" style="display: none;"> In this work, we propose a waveform based on Modulation on Conjugate-reciprocal Zeros (MOCZ) originally proposed for short-packet communications in [1], as a new Integrated Sensing and Communication (ISAC) waveform. Having previously established the key advantages of MOCZ for noncoherent and sporadic communication, here we leverage the optimal auto-correlation property of Binary MOCZ (BMOCZ) for sensing applications. Due to this property, which eliminates the need for separate communication and radar-centric waveforms, we propose a new frame structure for ISAC, where pilot sequences and preambles become obsolete and are completely removed from the frame. As a result, the data rate can be significantly improved. Aimed at (hardware-) cost-effective radar-sensing applications, we consider a Hybrid Digital-Analog (HDA) beamforming architecture for data transmission and radar sensing. We demonstrate via extensive simulations, that a communication data rate, significantly higher than existing standards can be achieved, while simultaneously achieving sensing performance comparable to state-of-the-art sensing systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.01760v1-abstract-full').style.display = 'none'; document.getElementById('2307.01760v1-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 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.00926">arXiv:2307.00926</a> <span> [<a href="https://arxiv.org/pdf/2307.00926">pdf</a>, <a href="https://arxiv.org/format/2307.00926">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"> Reduced-Complexity Cross-Domain Iterative Detection for OTFS Modulation via Delay-Doppler Decoupling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Liu%2C+M">Mengmeng Liu</a>, <a href="/search/cs?searchtype=author&query=Li%2C+S">Shuangyang Li</a>, <a href="/search/cs?searchtype=author&query=Bai%2C+B">Baoming Bai</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2307.00926v1-abstract-short" style="display: inline;"> In this paper, a reduced-complexity cross-domain iterative detection for orthogonal time frequency space (OTFS) modulation is proposed, which exploits channel properties in both time and delay-Doppler domains. Specifically, we first show that in the time domain effective channel, the path delay only introduces interference among samples in adjacent time slots, while the Doppler becomes a phase ter… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.00926v1-abstract-full').style.display = 'inline'; document.getElementById('2307.00926v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.00926v1-abstract-full" style="display: none;"> In this paper, a reduced-complexity cross-domain iterative detection for orthogonal time frequency space (OTFS) modulation is proposed, which exploits channel properties in both time and delay-Doppler domains. Specifically, we first show that in the time domain effective channel, the path delay only introduces interference among samples in adjacent time slots, while the Doppler becomes a phase term that does not affect the channel sparsity. This ``band-limited'' matrix structure motivates us to apply a reduced-size linear minimum mean square error (LMMSE) filter to eliminate the effect of delay in the time domain, while exploiting the cross-domain iteration for minimizing the effect of Doppler by noticing that the time and Doppler are a pair of Fourier dual. The state (MSE) evolution was derived and compared with bounds to verify the effectiveness of the proposed scheme. Simulation results demonstrate that the proposed scheme achieves almost the same error performance as the optimal detection, but only requires a reduced complexity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.00926v1-abstract-full').style.display = 'none'; document.getElementById('2307.00926v1-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> 3 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </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; this work has been accepted by SPAWC 2023</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.00850">arXiv:2307.00850</a> <span> [<a href="https://arxiv.org/pdf/2307.00850">pdf</a>, <a href="https://arxiv.org/format/2307.00850">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"> Fairness Scheduling in User-Centric Cell-Free Massive MIMO Wireless Networks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=G%C3%B6ttsch%2C+F">Fabian G枚ttsch</a>, <a href="/search/cs?searchtype=author&query=Osawa%2C+N">Noboru Osawa</a>, <a href="/search/cs?searchtype=author&query=Kanno%2C+I">Issei Kanno</a>, <a href="/search/cs?searchtype=author&query=Ohseki%2C+T">Takeo Ohseki</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2307.00850v3-abstract-short" style="display: inline;"> We consider a user-centric cell-free massive MIMO wireless network with $L$ remote radio units, each with $M$ antennas, serving $K_{\rm tot}$ user equipments (UEs). Most of the literature considers the regime $LM \gg K_{\rm tot}$, where the $K$ UEs are active on each time-frequency slot, and evaluates the system performance in terms of ergodic rates. In this paper, we take a quite different viewpo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.00850v3-abstract-full').style.display = 'inline'; document.getElementById('2307.00850v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.00850v3-abstract-full" style="display: none;"> We consider a user-centric cell-free massive MIMO wireless network with $L$ remote radio units, each with $M$ antennas, serving $K_{\rm tot}$ user equipments (UEs). Most of the literature considers the regime $LM \gg K_{\rm tot}$, where the $K$ UEs are active on each time-frequency slot, and evaluates the system performance in terms of ergodic rates. In this paper, we take a quite different viewpoint. We observe that the regime of $LM \gg K_{\rm tot}$ corresponds to a lightly loaded system with low sum spectral efficiency (SE). In contrast, in most relevant scenarios, the number of UEs is much larger than the total number of antennas, but users are not all active at the same time. To achieve high sum SE and handle $K_{\rm tot} \gg ML$, users must be scheduled over the time-frequency resource. The number of active users $K_{\rm act} \leq K_{\rm tot}$ must be chosen such that: 1) the network operates close to its maximum SE; 2) the active user set must be chosen dynamically over time in order to enforce fairness in terms of per-user time-averaged throughput rates. The fairness scheduling problem is formulated as the maximization of a concave componentwise non-decreasing network utility function of the per-user rates. Intermittent user activity imposes slot-by-slot coding/decoding which prevents the achievability of ergodic rates. Hence, we model the per-slot service rates using information outage probability. To obtain a tractable problem, we make a decoupling assumption on the CDF of the instantaneous mutual information seen at each UE $k$ receiver. We approximately enforce this condition with a conflict graph that prevents the simultaneous scheduling of users with large pilot contamination and propose an adaptive scheme for instantaneous service rate scheduling. Overall, the proposed dynamic scheduling is robust to system model uncertainties and can be easily implemented in practice. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.00850v3-abstract-full').style.display = 'none'; document.getElementById('2307.00850v3-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.08704">arXiv:2306.08704</a> <span> [<a href="https://arxiv.org/pdf/2306.08704">pdf</a>, <a href="https://arxiv.org/ps/2306.08704">ps</a>, <a href="https://arxiv.org/format/2306.08704">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 the Pulse Shaping for Delay-Doppler Communications </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Li%2C+S">Shuangyang Li</a>, <a href="/search/cs?searchtype=author&query=Yuan%2C+W">Weijie Yuan</a>, <a href="/search/cs?searchtype=author&query=Wei%2C+Z">Zhiqiang Wei</a>, <a href="/search/cs?searchtype=author&query=Yuan%2C+J">Jinhong Yuan</a>, <a href="/search/cs?searchtype=author&query=Bai%2C+B">Baoming Bai</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2306.08704v2-abstract-short" style="display: inline;"> In this paper, we study the pulse shaping for delay-Doppler (DD) communications. We start with constructing a basis function in the DD domain following the properties of the Zak transform. Particularly, we show that the constructed basis functions are globally quasi-periodic while locally twisted-shifted, and their significance in time and frequency domains are then revealed. We further analyze th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.08704v2-abstract-full').style.display = 'inline'; document.getElementById('2306.08704v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.08704v2-abstract-full" style="display: none;"> In this paper, we study the pulse shaping for delay-Doppler (DD) communications. We start with constructing a basis function in the DD domain following the properties of the Zak transform. Particularly, we show that the constructed basis functions are globally quasi-periodic while locally twisted-shifted, and their significance in time and frequency domains are then revealed. We further analyze the ambiguity function of the basis function, and show that fully localized ambiguity function can be achieved by constructing the basis function using periodic signals. More importantly, we prove that time and frequency truncating such basis functions naturally leads to approximate delay and Doppler orthogonalities, if the truncating windows are periodic within the support. Motivated by this, we propose a DD Nyquist pulse shaping scheme considering signals with periodicity. Finally, our conclusions are verified by using various strictly or approximately periodic pulses. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.08704v2-abstract-full').style.display = 'none'; document.getElementById('2306.08704v2-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 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.06648">arXiv:2306.06648</a> <span> [<a href="https://arxiv.org/pdf/2306.06648">pdf</a>, <a href="https://arxiv.org/format/2306.06648">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> </div> </div> <p class="title is-5 mathjax"> Information-Theoretic Limits of Bistatic Integrated Sensing and Communication </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=Jiao%2C+T">Tian Jiao</a>, <a href="/search/cs?searchtype=author&query=Wan%2C+K">Kai Wan</a>, <a href="/search/cs?searchtype=author&query=Wei%2C+Z">Zhiqiang Wei</a>, <a href="/search/cs?searchtype=author&query=Geng%2C+Y">Yanlin Geng</a>, <a href="/search/cs?searchtype=author&query=Li%2C+Y">Yonglong Li</a>, <a href="/search/cs?searchtype=author&query=Yang%2C+Z">Zai Yang</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2306.06648v4-abstract-short" style="display: inline;"> Bistatic sensing refers to scenarios where the transmitter (illuminating the target) and the sensing receiver (estimating the target state) are physically separated, in contrast to monostatic sensing, where both functions are co-located. In practical settings, bistatic sensing may be required either due to inherent system constraints or as a means to mitigate the strong self-interference encounter… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.06648v4-abstract-full').style.display = 'inline'; document.getElementById('2306.06648v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.06648v4-abstract-full" style="display: none;"> Bistatic sensing refers to scenarios where the transmitter (illuminating the target) and the sensing receiver (estimating the target state) are physically separated, in contrast to monostatic sensing, where both functions are co-located. In practical settings, bistatic sensing may be required either due to inherent system constraints or as a means to mitigate the strong self-interference encountered in monostatic configurations. A key practical challenge in bistatic radio-frequency radar systems is the synchronization and calibration of the separate transmitter and sensing receiver. In this paper, we are not concerned with these signal processing aspects and take a complementary information-theoretic perspective on bistatic integrated sensing and communication (ISAC). Namely, we aim to characterize the capacity-distortion function-the fundamental tradeoff between communication capacity and sensing accuracy. We consider a general discrete channel model for a bistatic ISAC system and derive a multi-letter representation of its capacity-distortion function. Then, we establish single-letter upper and lower bounds and provide exact single-letter characterizations for degraded bistatic ISAC channels. Furthermore, we extend our analysis to a bistatic ISAC broadcast channel and derive the capacity-distortion region with a single-letter characterization in the degraded case. Numerical examples illustrate the theoretical results, highlighting the benefits of ISAC over separate communication and sensing, as well as the role of leveraging communication to assist sensing in bistatic systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.06648v4-abstract-full').style.display = 'none'; document.getElementById('2306.06648v4-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 March, 2025; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </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">37 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/2305.08363">arXiv:2305.08363</a> <span> [<a href="https://arxiv.org/pdf/2305.08363">pdf</a>, <a href="https://arxiv.org/format/2305.08363">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"> User-Centric Clustering Under Fairness Scheduling in Cell-Free Massive MIMO </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cs?searchtype=author&query=G%C3%B6ttsch%2C+F">Fabian G枚ttsch</a>, <a href="/search/cs?searchtype=author&query=Osawa%2C+N">Noboru Osawa</a>, <a href="/search/cs?searchtype=author&query=Amano%2C+Y">Yoshiaki Amano</a>, <a href="/search/cs?searchtype=author&query=Kanno%2C+I">Issei Kanno</a>, <a href="/search/cs?searchtype=author&query=Yamazaki%2C+K">Kosuke Yamazaki</a>, <a href="/search/cs?searchtype=author&query=Caire%2C+G">Giuseppe Caire</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="2305.08363v1-abstract-short" style="display: inline;"> We consider fairness scheduling in a user-centric cell-free massive MIMO network, where $L$ remote radio units, each with $M$ antennas, serve $K_{\rm tot} \approx LM$ user equipments (UEs). Recent results show that the maximum network sum throughput is achieved where $K_{\rm act} \approx \frac{LM}{2}$ UEs are simultaneously active in any given time-frequency slots. However, the number of users… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.08363v1-abstract-full').style.display = 'inline'; document.getElementById('2305.08363v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.08363v1-abstract-full" style="display: none;"> We consider fairness scheduling in a user-centric cell-free massive MIMO network, where $L$ remote radio units, each with $M$ antennas, serve $K_{\rm tot} \approx LM$ user equipments (UEs). Recent results show that the maximum network sum throughput is achieved where $K_{\rm act} \approx \frac{LM}{2}$ UEs are simultaneously active in any given time-frequency slots. However, the number of users $K_{\rm tot}$ in the network is usually much larger. This requires that users are scheduled over the time-frequency resource and achieve a certain throughput rate as an average over the slots. We impose throughput fairness among UEs with a scheduling approach aiming to maximize a concave component-wise non-decreasing network utility function of the per-user throughput rates. In cell-free user-centric networks, the pilot and cluster assignment is usually done for a given set of active users. Combined with fairness scheduling, this requires pilot and cluster reassignment at each scheduling slot, involving an enormous overhead of control signaling exchange between network entities. We propose a fixed pilot and cluster assignment scheme (independent of the scheduling decisions), which outperforms the baseline method in terms of UE throughput, while requiring much less control information exchange between network entities. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.08363v1-abstract-full').style.display = 'none'; document.getElementById('2305.08363v1-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </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">arXiv admin note: text overlap with arXiv:2211.15294</span> </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" 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