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Optimal index Codes For A New Class of Interlinked Cycle Structure

IEEE COMMUNICATIONS LETTERS 2018年第4期22卷 684-687页

作者： Vaddi, Mahesh Babu Rajan, B. Sundar Indian Inst Sci Dept Elect Commun Engn Bengaluru 560012 India

The interlinked cycle (IC) structure that generalizes cycles and cliques was defined by Thapa, Ong, and Johnson. Interlinked-cycle-cover (ICC) scheme that leverages IC structures in digraphs to construct scalar linear index codes was proposed. A class of infinitely many digraphs, where the proposed scalar linear codes based on ICC scheme are optimal were characterized by Thapa et. al. In this paper, we provide an addition to this class by providing optimal length index codes for IC structures with one cycle among non-inner vertex set.

关键词： index coding side information

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Optimality of Orthogonal Access for One-Dimensional Convex Cellular Networks

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IEEE COMMUNICATIONS LETTERS 2013年第9期17卷 1770-1773页

作者： Maleki, Hamed Jafar, Syed A. Univ Calif Irvine CPCC Irvine CA 92717 USA

It is shown that a greedy orthogonal access scheme achieves the sum degrees of freedom (DoF) of all one-dimensional (all nodes placed along a straight line) convex cellular networks (where cells are convex regions) when no channel knowledge is available at the transmitters except the knowledge of the network topology. In general, optimality of orthogonal access holds neither for two-dimensional convex cellular networks nor for one-dimensional non-convex cellular networks, thus revealing a fundamental limitation that arises when both one-dimensional and convex properties are simultaneously enforced. The result also establishes the sum capacity of the corresponding class of index coding problems.

关键词： Cellular networks interference degrees of freedom index coding

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The Capacity of 3 User Linear Computation Broadcast

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IEEE TRANSACTIONS ON INFORMATION THEORY 2024年第6期70卷 4414-4438页

作者： Yao, Yuhang Jafar, Syed A. Univ Calif Irvine Ctr Pervas Commun & Comp CPCC Dept Elect Engn & Comp Sci Irvine CA 92697 USA

The K User Linear Computation Broadcast (LCBC) problem is comprised of d dimensional data (from F-q ), that is fully available to a central server, and K users, who require various linear computations of the data, and have prior knowledge of various linear functions of the data as side-information. The optimal broadcast cost is the minimum number of q-ary symbols to be broadcast by the server per computation instance, for every user to retrieve its desired computation. The reciprocal of the optimal broadcast cost is called the capacity. The main contribution of this paper is the exact capacity characterization for the K = 3 user LCBC for all cases, i.e., for arbitrary finite fields F-q , arbitrary data dimension d, and arbitrary linear side-informations and demands at each user. A remarkable aspect of the converse (impossibility result) is that unlike the 2 user LCBC whose capacity was determined previously, the entropic formulation (where the entropies of demands and side-informations are specified, but not their functional forms) is insufficient to obtain a tight converse for the 3 user LCBC. Instead, the converse exploits functional submodularity. Notable aspects of achievability include sufficiency of vector linear coding schemes, subspace decompositions that parallel those found previously by Yao Wang in degrees of freedom (DoF) studies of wireless broadcast networks, and efficiency tradeoffs that lead to a constrained waterfilling solution. Random coding arguments are invoked to resolve compatibility issues that arise as each user has a different view of the subspace decomposition, conditioned on its own side-information.

关键词： Channel coding indexes Costs Vectors Servers Distributed databases Symbols Capacity broadcast index coding coded computation

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Topological Interference Management With Transmitter Cooperation

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IEEE TRANSACTIONS ON INFORMATION THEORY 2015年第11期61卷 6107-6130页

作者： Yi, Xinping Gesbert, David Tech Univ Berlin Dept Elect Engn & Comp Sci D-10587 Berlin Germany EURECOM Mobile Commun Dept F-06560 Sophia Antipolis France

Interference networks with no channel state information at the transmitter except for the knowledge of the connectivity graph have been recently studied under the topological interference management framework. In this paper, we consider a similar problem with topological knowledge but in a distributed broadcast channel setting, i.e., a network where transmitter cooperation is enabled. We show that the topological information can also be exploited in this case to strictly improve the degrees of freedom (DoF) as long as the network is not fully connected, which is a reasonable assumption in practice. Achievability schemes from graph theoretic and interference alignment perspectives are proposed. Together with outer bounds built upon generator sequence, the concept of compound channel settings, and the relation to index coding, we characterize the symmetric DoF for the so-called regular networks with constant number of interfering links, and identify the sufficient and/or necessary conditions for the arbitrary network topologies to achieve a certain amount of symmetric DoF.

关键词： Degrees of freedom (DoF) index coding interference alignment interference channel transmitter cooperation

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The DoF Region of the Three-Receiver Gaussian MIMO Broadcast Channel With Receiver Message Side Information

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IEEE TRANSACTIONS ON COMMUNICATIONS 2017年第5期65卷 2000-2010页

作者： Asadi, Behzad Ong, Lawrence Johnson, Sarah J. Univ Newcastle Sch Elect Engn & Comp Sci Callaghan NSW 2308 Australia

We consider the three-receiver Gaussian multiple-input multiple-output broadcast channel with an arbitrary number of antennas at the transmitter and the receivers. We investigate the degrees-of-freedom (DoF) region of the channel when each receiver requests a private message, and may know some of the messages requested by the other receivers as receiver message side information (RMSI). We establish the DoF region of the channel for all 16 possible non-isomorphic RMSI configurations by deriving tight inner and outer bounds on the region. To derive the inner bounds, we first propose a scheme for each RMSI configuration, which exploits both the null space and the side information of the receivers. We then use these schemes in conjunction with time sharing for 15 RMSI configurations, and with time sharing and two-symbol extension for the remaining one. To derive the outer bounds, we construct enhanced versions of the channel for each RMSI configuration, and upper bound their DoF region. After establishing the DoF region, in the case where all the nodes have the same number of antennas, we introduce some common properties of the DoF region, and the capacity region of the index coding problem.

关键词： MIMO broadcast channel degrees-of-freedom region side information index coding

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On coding for Cache-Aided Delivery of Dynamic Correlated Content

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2018年第8期36卷 1666-1681页

作者： Hassanzadeh, Parisa Tulino, Antonia M. Llorca, Jaime Erkip, Elza NYU Dept Elect & Comp Engn Brooklyn NY 11201 USA Nokia Bell Labs Holmdel NJ 07733 USA Univ Naples Federico II Dept Elect Engn & Informat Technol I-80125 Naples Italy

Cache-aided coded multicast leverages side information at wireless edge caches to efficiently serve multiple unicast demands via common multicast transmissions, leading to load reductions that are proportional to the aggregate cache size. However, the increasingly dynamic, unpredictable, and personalized nature of the content that users consume challenges the efficiency of existing caching-based solutions in which only exact content reuse is explored. This paper generalizes the cacheaided coded multicast problem to specifically account for the correlation among content files, such as, for example, the one between updated versions of dynamic data. It is shown that: 1) caching content pieces based on their correlation with the rest of the library and 2) jointly compressing requested files using cached information as references during delivery, can provide load reductions that go beyond those achieved with existing schemes. This is accomplished via the design of a class of correlation-aware achievable schemes, shown to significantly outperform the state-of-the-art correlation-unaware solutions. Our results show that as we move towards real-time and/or personalized media dominated services, where exact cache hits are almost non-existent but updates can exhibit high levels of correlation, network cached information can still be useful as references for network compression.

关键词： Coded caching coded multicasting correlated library dynamic data network coding index coding network compression content distribution

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Lattice index Codes From Algebraic Number Fields

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IEEE TRANSACTIONS ON INFORMATION THEORY 2017年第4期63卷 2098-2112页

作者： Huang, Yu-Chih Natl Taipei Univ Dept Commun Engn New Taipei Taiwan

Broadcasting K independent messages to multiple users where each user demands all the messages and already has a subset of the messages as side information is studied. Recently, Natarajan et al. proposed a novel broadcasting strategy called lattice index coding, which adopts lattices constructed over some principal ideal domains (PID) for transmission. Using the structure of lattices over PID, they showed that this scheme provides uniform side information gain for any side information configuration, a desired property which essentially guarantees a fair signal-to-noise ratio gain when normalized by the amount of information contained in side information. In this paper, we generalize this strategy to a general ring of algebraic integers, which may not be a PID. Upper and lower bounds on the side information gains for the proposed scheme constructed over some interesting classes of number fields are provided and are shown to coincide asymptotically in message rate. This generalization substantially enlarges the design space and partially includes the scheme by Natarajan et al. as a special case. Perhaps more importantly, in addition to side information gains, the proposed lattice index codes benefit from diversity gains inherent in constellations carved from number fields when used over Rayleigh fading channel. Some interesting examples are provided for which the proposed scheme allows the messages to be from the same field.

关键词： Lattice codes index coding broadcast channels side information

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Data Dissemination With Side Information and Feedback

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2014年第9期13卷 4708-4720页

作者： Dai, Mingjun Shum, Kenneth W. Sung, Chi Wan Shenzhen Univ Coll Informat Engn Shenzhen 518060 Peoples R China Xidian Univ State Key Lab Integrated Serv Networks Xian Peoples R China Chinese Univ Hong Kong Inst Network Coding Shatin Hong Kong Peoples R China City Univ Hong Kong Coll Sci & Engn Dept Elect Engn Kowloon Hong Kong Peoples R China

index coding (IC), which can be regarded as a special class of network coding, deals with the problem of sending a number of packets to a group of receivers, each of which requests one packet and may have some other packets in its cache. This paper generalizes the IC problem in that both the packet requested by a receiver and the packets in its cache can be linear combinations of the packets. To minimize the number of transmissions required, a heuristic algorithm based on the idea of partitioning the users into coding groups is designed. To realize this idea, a polynomial time algorithm to determine whether a set of users form a coding group over the binary field or a field with a size larger than the number of users is constructed. For users that form a coding group, the corresponding encoding vector can be also found. A lower bound is derived in order to evaluate the performance of the heuristic algorithm. Numerical results show that the number of transmissions required by the heuristic algorithm and the lower bound both grow roughly linearly with the number of users, and the heuristic algorithm outperforms some benchmark algorithms.

关键词： index coding network coding data dissemination coded side information broadcast relay channel

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index Coded-NOMA in Vehicular Ad Hoc Networks

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2022年第9期71卷 10073-10087页

作者： Pazhoor, Sreelakshmi Pachat, Jesy Mahesh, Anjana Ambika Deepthi, P. P. Rajan, B. Sundar Natl Inst Technol Elect & Commun Dept Calicut 673601 Kerala India Indian Inst Sci Dept Elect Commun Engn Bangalore 560012 Karnataka India

The demand for multimedia services is growing day by day in vehicular ad hoc networks (VANETs), resulting in high spectral usage and network congestion. Non-orthogonal multiple access (NOMA) is a promising wireless communication technique to solve the problems related to spectral efficiency effectively. The index coding (IC) is a powerful method to improve spectral utilization, where a sender aims to satisfy the needs of multiple receivers with a minimum number of transmissions. By combining these two approaches, in this work, we propose a novel technique called index coded NOMA (IC-NOMA), where we apply NOMA techniques on index coded data to reduce the number of transmissions further. This work shows that the IC-NOMA system demands a specific design for index codes to reap the advantages of NOMA. We have done the feasibility analysis of the proposed method in a general scenario and proposed an index code design to integrate IC over NOMA for the best efficiency. Through detailed analytical studies it is validated that the proposed transmission system provides improved spectral efficiency and power saving compared to conventional IC systems.

关键词： indexes NOMA Encoding Codes Integrated circuits Receivers Bandwidth Caching index coding Non-orthogonal multiple access vehicular communications

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Full Coded Caching Gains for Cache-Less Users

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IEEE TRANSACTIONS ON INFORMATION THEORY 2020年第12期66卷 7635-7651页

作者： Lampiris, Eleftherios Elia, Petros EURECOM F-06410 Sophia Antipolis France Tech Univ Berlin Dept Elect Engn & Comp Sci D-10587 Berlin Germany EURECOM Dept Commun Syst F-06410 Sophia Antipolis France

Within the context of coded caching, the work reveals the interesting connection between having multiple transmitters and having heterogeneity in the cache sizes of the receivers. Our work effectively shows that having multiple transmit antennas - while providing full multiplexing gains - can also simultaneously completely remove the performance penalties that are typically associated to cache-size unevenness. Focusing on the multiple-input single-output Broadcast Channel, the work first identifies the performance limits of the extreme case where cache-aided users coincide with users that do not have caches, and then expands the analysis to the case where both user groups are cache-aided but with heterogeneous cache-sizes. In the first case, the main contribution is a new algorithm that employs perfect matchings on a bipartite graph to offer full multiplexing as well as full coded-caching gains to both cache-aided as well as cache-less users. An interesting conclusion is that, starting from a single-stream centralized coded caching setting with normalized cache size gamma, then adding L antennas allows for the addition of up to approximately L/gamma extra cache-less users, at no added delay costs. Similarly surprising is the finding that, beginning with a single-antenna hybrid system (with both cache-less and cacheaided users), then adding L - 1 antennas to the transmitter, as well as endowing the cache-less users with a cumulative normalized cache size Gamma(2), increases the Degrees of Freedom by a multiplicative factor of up to Gamma(2) + L.

关键词： Caching networks coded caching heterogeneous cache sizes delivery rate uncoded cache placement index coding MISO broadcast channel network coding

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