Given integers $n > k > 0$, and a set of integers $L subset [0, k-1]$, an $L$-system is a family of sets $mathcal{F} subset binom{[n]}{k}$ such that $|F cap F'| in L$ for distinct $F, F'in mathcal{F}$. $L$-systems correspond to independent sets in a certain generalized Johnson graph $G(n, k, L)$, so that the maximum size of an $L$-system is equivalent to finding the independence number of the graph $G(n, k, L)$. The Lov'asz number $vartheta(G)$ is a semidefinite programming approximation of the independence number of a graph $G$. In this paper, we determine the order of magnitude of $vartheta(G(n, k, L))$ of any generalized Johnson graph with $k$ and $L$ fixed and $nrightarrow infty$. As an application of this theorem, we give an explicit construction of a graph $G$ on $n$ vertices with large gap between the Lov'asz number and the Shannon capacity $c(G)$. Specifically, we prove that for any $epsilon > 0$, for infinitely many $n$ there is a generalized Johnson graph $G$ on $n$ vertices which has ratio $vartheta(G)/c(G) = Omega(n^{1-epsilon})$, which greatly improves on the best known explicit construction.
{"title":"$L$-systems and the Lovász number","authors":"William Linz","doi":"arxiv-2402.05818","DOIUrl":"https://doi.org/arxiv-2402.05818","url":null,"abstract":"Given integers $n > k > 0$, and a set of integers $L subset [0, k-1]$, an\u0000$L$-system is a family of sets $mathcal{F} subset binom{[n]}{k}$ such that\u0000$|F cap F'| in L$ for distinct $F, F'in mathcal{F}$. $L$-systems correspond\u0000to independent sets in a certain generalized Johnson graph $G(n, k, L)$, so\u0000that the maximum size of an $L$-system is equivalent to finding the\u0000independence number of the graph $G(n, k, L)$. The Lov'asz number\u0000$vartheta(G)$ is a semidefinite programming approximation of the independence\u0000number of a graph $G$. In this paper, we determine the order of magnitude of $vartheta(G(n, k, L))$\u0000of any generalized Johnson graph with $k$ and $L$ fixed and $nrightarrow\u0000infty$. As an application of this theorem, we give an explicit construction of\u0000a graph $G$ on $n$ vertices with large gap between the Lov'asz number and the\u0000Shannon capacity $c(G)$. Specifically, we prove that for any $epsilon > 0$,\u0000for infinitely many $n$ there is a generalized Johnson graph $G$ on $n$\u0000vertices which has ratio $vartheta(G)/c(G) = Omega(n^{1-epsilon})$, which\u0000greatly improves on the best known explicit construction.","PeriodicalId":501433,"journal":{"name":"arXiv - CS - Information Theory","volume":"60 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This book delves into the burgeoning field of quantum resource theories, a novel and vibrant area of research within quantum information science that seeks to unify diverse quantum phenomena under a single framework. By recognizing various attributes of physical systems as "resources," this approach offers a fresh perspective on quantum phenomena, transforming our understanding and application of concepts such as quantum entanglement, coherence, and more. With a focus on the pedagogical, the book aims to equip readers with the advanced mathematical tools and physical principles needed to navigate and contribute to this rapidly evolving field. It covers a wide range of topics, from the foundational aspects of quantum mechanics and quantum information to detailed explorations of specific resource theories, including entanglement, asymmetry, and thermodynamics. Through rigorous mathematical exposition and a unique axiomatic approach, the book provides deep insights into the operational and conceptual frameworks that underpin quantum resource theories, making it an invaluable resource for graduate students, early-career researchers, and anyone interested in the cutting-edge developments in quantum information science.
{"title":"Resources of the Quantum World","authors":"Gilad Gour","doi":"arxiv-2402.05474","DOIUrl":"https://doi.org/arxiv-2402.05474","url":null,"abstract":"This book delves into the burgeoning field of quantum resource theories, a\u0000novel and vibrant area of research within quantum information science that\u0000seeks to unify diverse quantum phenomena under a single framework. By\u0000recognizing various attributes of physical systems as \"resources,\" this\u0000approach offers a fresh perspective on quantum phenomena, transforming our\u0000understanding and application of concepts such as quantum entanglement,\u0000coherence, and more. With a focus on the pedagogical, the book aims to equip\u0000readers with the advanced mathematical tools and physical principles needed to\u0000navigate and contribute to this rapidly evolving field. It covers a wide range\u0000of topics, from the foundational aspects of quantum mechanics and quantum\u0000information to detailed explorations of specific resource theories, including\u0000entanglement, asymmetry, and thermodynamics. Through rigorous mathematical\u0000exposition and a unique axiomatic approach, the book provides deep insights\u0000into the operational and conceptual frameworks that underpin quantum resource\u0000theories, making it an invaluable resource for graduate students, early-career\u0000researchers, and anyone interested in the cutting-edge developments in quantum\u0000information science.","PeriodicalId":501433,"journal":{"name":"arXiv - CS - Information Theory","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Frameproof codes have been extensively studied for many years due to their application in copyright protection and their connection to extremal set theory. In this paper, we investigate upper bounds on the cardinality of wide-sense $t$-frameproof codes. For $t=2$, we apply results from Sperner theory to give a better upper bound, which significantly improves a recent bound by Zhou and Zhou. For $tgeq 3$, we provide a general upper bound by establishing a relation between wide-sense frameproof codes and cover-free families. Finally, when the code length $n$ is at most $frac{15+sqrt{33}}{24}(t-1)^2$, we show that a wide-sense $t$-frameproof code has at most $n$ codewords, and the unique optimal code consists of all weight-one codewords. As byproducts, our results improve several best known results on binary $t$-frameproof codes.
{"title":"Improved upper bounds for wide-sense frameproof codes","authors":"Yuhao Zhao, Xiande Zhang","doi":"arxiv-2402.05596","DOIUrl":"https://doi.org/arxiv-2402.05596","url":null,"abstract":"Frameproof codes have been extensively studied for many years due to their\u0000application in copyright protection and their connection to extremal set\u0000theory. In this paper, we investigate upper bounds on the cardinality of\u0000wide-sense $t$-frameproof codes. For $t=2$, we apply results from Sperner\u0000theory to give a better upper bound, which significantly improves a recent\u0000bound by Zhou and Zhou. For $tgeq 3$, we provide a general upper bound by\u0000establishing a relation between wide-sense frameproof codes and cover-free\u0000families. Finally, when the code length $n$ is at most\u0000$frac{15+sqrt{33}}{24}(t-1)^2$, we show that a wide-sense $t$-frameproof code\u0000has at most $n$ codewords, and the unique optimal code consists of all\u0000weight-one codewords. As byproducts, our results improve several best known\u0000results on binary $t$-frameproof codes.","PeriodicalId":501433,"journal":{"name":"arXiv - CS - Information Theory","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Coded blockchains have acquired prominence in the recent past as a promising approach to slash the storage costs as well as to facilitate scalability. Within this class, Luby Transform (LT) coded blockchains are an appealing choice for scalability in heterogeneous networks owing to the availability of a wide range of low-complexity LT decoders. While these architectures have been studied from the aspects of storage savings and scalability, not much is known in terms of their security vulnerabilities. Pointing at this research gap, in this work, we present novel denial-of-service (DoS) threats on LT coded blockchains that target nodes with specific decoding capabilities, thereby preventing them from joining the network. Our proposed threats are non-oblivious in nature, wherein adversaries gain access to the archived blocks, and choose to execute their threat on a subset of them based on underlying coding scheme. We show that our optimized threats can achieve the same level of damage as that of blind attacks, however, with limited amount of resources. This is the first work of its kind that opens up new questions on designing coded blockchains to jointly provide storage savings, scalability and resilience to optimized threats.
{"title":"Optimized Denial-of-Service Threats on the Scalability of LT Coded Blockchains","authors":"Harikrishnan K., J. Harshan, Anwitaman Datta","doi":"arxiv-2402.05620","DOIUrl":"https://doi.org/arxiv-2402.05620","url":null,"abstract":"Coded blockchains have acquired prominence in the recent past as a promising\u0000approach to slash the storage costs as well as to facilitate scalability.\u0000Within this class, Luby Transform (LT) coded blockchains are an appealing\u0000choice for scalability in heterogeneous networks owing to the availability of a\u0000wide range of low-complexity LT decoders. While these architectures have been\u0000studied from the aspects of storage savings and scalability, not much is known\u0000in terms of their security vulnerabilities. Pointing at this research gap, in\u0000this work, we present novel denial-of-service (DoS) threats on LT coded\u0000blockchains that target nodes with specific decoding capabilities, thereby\u0000preventing them from joining the network. Our proposed threats are\u0000non-oblivious in nature, wherein adversaries gain access to the archived\u0000blocks, and choose to execute their threat on a subset of them based on\u0000underlying coding scheme. We show that our optimized threats can achieve the\u0000same level of damage as that of blind attacks, however, with limited amount of\u0000resources. This is the first work of its kind that opens up new questions on\u0000designing coded blockchains to jointly provide storage savings, scalability and\u0000resilience to optimized threats.","PeriodicalId":501433,"journal":{"name":"arXiv - CS - Information Theory","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We consider the capacity of emph{treelike committee machines} (TCM) neural networks. Relying on Random Duality Theory (RDT), cite{Stojnictcmspnncaprdt23} recently introduced a generic framework for their capacity analysis. An upgrade based on the so-called emph{partially lifted} RDT (pl RDT) was then presented in cite{Stojnictcmspnncapliftedrdt23}. Both lines of work focused on the networks with the most typical, emph{sign}, activations. Here, on the other hand, we focus on networks with other, more general, types of activations and show that the frameworks of cite{Stojnictcmspnncaprdt23,Stojnictcmspnncapliftedrdt23} are sufficiently powerful to enable handling of such scenarios as well. In addition to the standard emph{linear} activations, we uncover that particularly convenient results can be obtained for two very commonly used activations, namely, the emph{quadratic} and emph{rectified linear unit (ReLU)} ones. In more concrete terms, for each of these activations, we obtain both the RDT and pl RDT based memory capacities upper bound characterization for emph{any} given (even) number of the hidden layer neurons, $d$. In the process, we also uncover the following two, rather remarkable, facts: 1) contrary to the common wisdom, both sets of results show that the bounding capacity decreases for large $d$ (the width of the hidden layer) while converging to a constant value; and 2) the maximum bounding capacity is achieved for the networks with precisely textbf{emph{two}} hidden layer neurons! Moreover, the large $d$ converging values are observed to be in excellent agrement with the statistical physics replica theory based predictions.
{"title":"Fixed width treelike neural networks capacity analysis -- generic activations","authors":"Mihailo Stojnic","doi":"arxiv-2402.05696","DOIUrl":"https://doi.org/arxiv-2402.05696","url":null,"abstract":"We consider the capacity of emph{treelike committee machines} (TCM) neural\u0000networks. Relying on Random Duality Theory (RDT), cite{Stojnictcmspnncaprdt23}\u0000recently introduced a generic framework for their capacity analysis. An upgrade\u0000based on the so-called emph{partially lifted} RDT (pl RDT) was then presented\u0000in cite{Stojnictcmspnncapliftedrdt23}. Both lines of work focused on the\u0000networks with the most typical, emph{sign}, activations. Here, on the other\u0000hand, we focus on networks with other, more general, types of activations and\u0000show that the frameworks of\u0000cite{Stojnictcmspnncaprdt23,Stojnictcmspnncapliftedrdt23} are sufficiently\u0000powerful to enable handling of such scenarios as well. In addition to the\u0000standard emph{linear} activations, we uncover that particularly convenient\u0000results can be obtained for two very commonly used activations, namely, the\u0000emph{quadratic} and emph{rectified linear unit (ReLU)} ones. In more concrete\u0000terms, for each of these activations, we obtain both the RDT and pl RDT based\u0000memory capacities upper bound characterization for emph{any} given (even)\u0000number of the hidden layer neurons, $d$. In the process, we also uncover the\u0000following two, rather remarkable, facts: 1) contrary to the common wisdom, both\u0000sets of results show that the bounding capacity decreases for large $d$ (the\u0000width of the hidden layer) while converging to a constant value; and 2) the\u0000maximum bounding capacity is achieved for the networks with precisely\u0000textbf{emph{two}} hidden layer neurons! Moreover, the large $d$ converging\u0000values are observed to be in excellent agrement with the statistical physics\u0000replica theory based predictions.","PeriodicalId":501433,"journal":{"name":"arXiv - CS - Information Theory","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Reconfigurable intelligent surface (RIS) is a key technology to control the communication environment in future wireless networks. Recently, beyond diagonal RIS (BD-RIS) emerged as a generalization of RIS achieving larger coverage through additional tunable impedance components interconnecting the RIS elements. However, conventional RIS and BD-RIS can effectively serve only users in their proximity, resulting in limited coverage. To overcome this limitation, in this paper, we investigate distributed RIS, whose elements are distributed over a wide region, in opposition to localized RIS commonly considered in the literature. The scaling laws of distributed BD-RIS reveal that it offers significant gains over distributed conventional RIS and localized BD-RIS, enabled by its interconnections allowing signal propagation within the BD-RIS. To assess the practical performance of distributed BD-RIS, we model and optimize BD-RIS with lossy interconnections through transmission line theory. Our model accounts for phase changes and losses over the BD-RIS interconnections arising when the interconnection lengths are not much smaller than the wavelength. Numerical results show that the performance of localized BD-RIS is only slightly impacted by losses, given the short interconnection lengths. Besides, distributed BD-RIS can achieve orders of magnitude of gains over conventional RIS, even in the presence of low losses.
{"title":"Localized and Distributed Beyond Diagonal Reconfigurable Intelligent Surfaces with Lossy Interconnections: Modeling and Optimization","authors":"Matteo Nerini, Golsa Ghiaasi, Bruno Clerckx","doi":"arxiv-2402.05881","DOIUrl":"https://doi.org/arxiv-2402.05881","url":null,"abstract":"Reconfigurable intelligent surface (RIS) is a key technology to control the\u0000communication environment in future wireless networks. Recently, beyond\u0000diagonal RIS (BD-RIS) emerged as a generalization of RIS achieving larger\u0000coverage through additional tunable impedance components interconnecting the\u0000RIS elements. However, conventional RIS and BD-RIS can effectively serve only\u0000users in their proximity, resulting in limited coverage. To overcome this\u0000limitation, in this paper, we investigate distributed RIS, whose elements are\u0000distributed over a wide region, in opposition to localized RIS commonly\u0000considered in the literature. The scaling laws of distributed BD-RIS reveal\u0000that it offers significant gains over distributed conventional RIS and\u0000localized BD-RIS, enabled by its interconnections allowing signal propagation\u0000within the BD-RIS. To assess the practical performance of distributed BD-RIS,\u0000we model and optimize BD-RIS with lossy interconnections through transmission\u0000line theory. Our model accounts for phase changes and losses over the BD-RIS\u0000interconnections arising when the interconnection lengths are not much smaller\u0000than the wavelength. Numerical results show that the performance of localized\u0000BD-RIS is only slightly impacted by losses, given the short interconnection\u0000lengths. Besides, distributed BD-RIS can achieve orders of magnitude of gains\u0000over conventional RIS, even in the presence of low losses.","PeriodicalId":501433,"journal":{"name":"arXiv - CS - Information Theory","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This letter considers a two-panel massive multiple-input multiple-output (MIMO) communication system, where the base station (BS) is equipped with two antenna panels that may use different frequency bands for communication. By exploiting the geometric relationships between antenna panels, efficient channel inference methods across antenna panels are proposed to reduce the overhead of real-time channel estimation. Four scenarios are considered, namely far-field free-space, near-field free-space, multi-path sharing far-field scatterers, and multi-path sharing near-field scatterers. For both far-field and near-field free-space scenarios, we show that the channel of one panel can be fully inferred from that of the other panel, as long as the multi-path components (MPCs) composing the channel can be resolved. On the other hand, for the multi-path scenarios sharing far-field or near-field scatterers, only the angles or range of angles of the MPCs can be inferred, respectively. Simulation results based on commercial 3D ray-tracing software are presented to validate our developed channel inference techniques.
本文探讨了双天线板大规模多输入多输出（MIMO）通信系统，其中基站（BS）配备了两个天线板，可使用不同的频段进行通信。通过利用天线板之间的几何关系，提出了跨天线板的高效信道推断方法，以减少实时信道估计的开销。本文考虑了四种情况，即远场自由空间、近场自由空间、多路径共享远场散射体和多路径共享近场散射体。对于远场和近场自由空间场景，我们的研究表明，只要组成信道的多路径分量（MPCs）能够被解析，一个面板的信道完全可以从另一个面板的信道中推断出来。另一方面，对于共享远场或近场散射体的多路径情况，只能分别推断出 MPC 的角度或角度范围。本文介绍了基于商用 3D 射线跟踪软件的仿真结果，以验证我们开发的信道推断技术。
{"title":"Can Channels be Fully Inferred Between Two Antenna Panels?","authors":"Y. Qiu, D. W, Y. Zeng","doi":"arxiv-2402.05387","DOIUrl":"https://doi.org/arxiv-2402.05387","url":null,"abstract":"This letter considers a two-panel massive multiple-input multiple-output\u0000(MIMO) communication system, where the base station (BS) is equipped with two\u0000antenna panels that may use different frequency bands for communication. By\u0000exploiting the geometric relationships between antenna panels, efficient\u0000channel inference methods across antenna panels are proposed to reduce the\u0000overhead of real-time channel estimation. Four scenarios are considered, namely\u0000far-field free-space, near-field free-space, multi-path sharing far-field\u0000scatterers, and multi-path sharing near-field scatterers. For both far-field\u0000and near-field free-space scenarios, we show that the channel of one panel can\u0000be fully inferred from that of the other panel, as long as the multi-path\u0000components (MPCs) composing the channel can be resolved. On the other hand, for\u0000the multi-path scenarios sharing far-field or near-field scatterers, only the\u0000angles or range of angles of the MPCs can be inferred, respectively. Simulation\u0000results based on commercial 3D ray-tracing software are presented to validate\u0000our developed channel inference techniques.","PeriodicalId":501433,"journal":{"name":"arXiv - CS - Information Theory","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dephasing is a prominent noise mechanism that afflicts quantum information carriers, and it is one of the main challenges towards realizing useful quantum computation, communication, and sensing. Here we consider discrimination and estimation of bosonic dephasing channels, when using the most general adaptive strategies allowed by quantum mechanics. We reduce these difficult quantum problems to simple classical ones based on the probability densities defining the bosonic dephasing channels. By doing so, we rigorously establish the optimal performance of various distinguishability and estimation tasks and construct explicit strategies to achieve this performance. To the best of our knowledge, this is the first example of a non-Gaussian bosonic channel for which there are exact solutions for these tasks.
{"title":"Exact quantum sensing limits for bosonic dephasing channels","authors":"Zixin Huang, Ludovico Lami, Mark M. Wilde","doi":"arxiv-2402.05793","DOIUrl":"https://doi.org/arxiv-2402.05793","url":null,"abstract":"Dephasing is a prominent noise mechanism that afflicts quantum information\u0000carriers, and it is one of the main challenges towards realizing useful quantum\u0000computation, communication, and sensing. Here we consider discrimination and\u0000estimation of bosonic dephasing channels, when using the most general adaptive\u0000strategies allowed by quantum mechanics. We reduce these difficult quantum\u0000problems to simple classical ones based on the probability densities defining\u0000the bosonic dephasing channels. By doing so, we rigorously establish the\u0000optimal performance of various distinguishability and estimation tasks and\u0000construct explicit strategies to achieve this performance. To the best of our\u0000knowledge, this is the first example of a non-Gaussian bosonic channel for\u0000which there are exact solutions for these tasks.","PeriodicalId":501433,"journal":{"name":"arXiv - CS - Information Theory","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eduardo Noboro Tominaga, Onel Luis Alcaraz López, Tommy Svensson, Richard Demo Souza, Hirley Alves
Contemporary wireless communication systems rely on Multi-User Multiple-Input Multiple-Output (MU-MIMO) techniques. In such systems, each Access Point (AP) is equipped with multiple antenna elements and serves multiple devices simultaneously. Notably, traditional systems utilize fixed antennas, i.e., antennas without any movement capabilities, while the idea of movable antennas has recently gained traction among the research community. By moving in a confined region, movable antennas are able to exploit the wireless channel variation in the continuous domain. This additional degree of freedom may enhance the quality of the wireless links, and consequently the communication performance. However, movable antennas for MU-MIMO proposed in the literature are complex, bulky, expensive and present a high power consumption. In this paper, we propose an alternative to such systems that has lower complexity and lower cost. More specifically, we propose the incorporation of rotation capabilities to APs equipped with Uniform Linear Arrays (ULAs) of antennas. We consider the uplink of an indoor scenario where the AP serves multiple devices simultaneously. The optimal rotation of the ULA is computed based on estimates of the positions of the active devices and aiming at maximizing the per-user mean achievable Spectral Efficiency (SE). Adopting a spatially correlated Rician channel model, our numerical results show that the rotation capabilities of the AP can bring substantial improvements in the SE in scenarios where the line-of-sight component of the channel vectors is strong. Moreover, our proposed system is robust against imperfect positioning estimates.
{"title":"On the Spectral Efficiency of Indoor Wireless Networks with a Rotary Uniform Linear Array","authors":"Eduardo Noboro Tominaga, Onel Luis Alcaraz López, Tommy Svensson, Richard Demo Souza, Hirley Alves","doi":"arxiv-2402.05583","DOIUrl":"https://doi.org/arxiv-2402.05583","url":null,"abstract":"Contemporary wireless communication systems rely on Multi-User Multiple-Input\u0000Multiple-Output (MU-MIMO) techniques. In such systems, each Access Point (AP)\u0000is equipped with multiple antenna elements and serves multiple devices\u0000simultaneously. Notably, traditional systems utilize fixed antennas, i.e.,\u0000antennas without any movement capabilities, while the idea of movable antennas\u0000has recently gained traction among the research community. By moving in a\u0000confined region, movable antennas are able to exploit the wireless channel\u0000variation in the continuous domain. This additional degree of freedom may\u0000enhance the quality of the wireless links, and consequently the communication\u0000performance. However, movable antennas for MU-MIMO proposed in the literature\u0000are complex, bulky, expensive and present a high power consumption. In this\u0000paper, we propose an alternative to such systems that has lower complexity and\u0000lower cost. More specifically, we propose the incorporation of rotation\u0000capabilities to APs equipped with Uniform Linear Arrays (ULAs) of antennas. We\u0000consider the uplink of an indoor scenario where the AP serves multiple devices\u0000simultaneously. The optimal rotation of the ULA is computed based on estimates\u0000of the positions of the active devices and aiming at maximizing the per-user\u0000mean achievable Spectral Efficiency (SE). Adopting a spatially correlated\u0000Rician channel model, our numerical results show that the rotation capabilities\u0000of the AP can bring substantial improvements in the SE in scenarios where the\u0000line-of-sight component of the channel vectors is strong. Moreover, our\u0000proposed system is robust against imperfect positioning estimates.","PeriodicalId":501433,"journal":{"name":"arXiv - CS - Information Theory","volume":"208 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mustapha Bounoua, Giulio Franzese, Pietro Michiardi
The analysis of scientific data and complex multivariate systems requires information quantities that capture relationships among multiple random variables. Recently, new information-theoretic measures have been developed to overcome the shortcomings of classical ones, such as mutual information, that are restricted to considering pairwise interactions. Among them, the concept of information synergy and redundancy is crucial for understanding the high-order dependencies between variables. One of the most prominent and versatile measures based on this concept is O-information, which provides a clear and scalable way to quantify the synergy-redundancy balance in multivariate systems. However, its practical application is limited to simplified cases. In this work, we introduce S$Omega$I, which allows for the first time to compute O-information without restrictive assumptions about the system. Our experiments validate our approach on synthetic data, and demonstrate the effectiveness of S$Omega$I in the context of a real-world use case.
{"title":"S$Ω$I: Score-based O-INFORMATION Estimation","authors":"Mustapha Bounoua, Giulio Franzese, Pietro Michiardi","doi":"arxiv-2402.05667","DOIUrl":"https://doi.org/arxiv-2402.05667","url":null,"abstract":"The analysis of scientific data and complex multivariate systems requires\u0000information quantities that capture relationships among multiple random\u0000variables. Recently, new information-theoretic measures have been developed to\u0000overcome the shortcomings of classical ones, such as mutual information, that\u0000are restricted to considering pairwise interactions. Among them, the concept of\u0000information synergy and redundancy is crucial for understanding the high-order\u0000dependencies between variables. One of the most prominent and versatile\u0000measures based on this concept is O-information, which provides a clear and\u0000scalable way to quantify the synergy-redundancy balance in multivariate\u0000systems. However, its practical application is limited to simplified cases. In\u0000this work, we introduce S$Omega$I, which allows for the first time to compute\u0000O-information without restrictive assumptions about the system. Our experiments\u0000validate our approach on synthetic data, and demonstrate the effectiveness of\u0000S$Omega$I in the context of a real-world use case.","PeriodicalId":501433,"journal":{"name":"arXiv - CS - Information Theory","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139761409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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