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Multiple Multicasts With the Help of a Relay

IEEE TRANSACTIONS ON INFORMATION THEORY 2010年第12期56卷 6142-6158页

作者： Guenduez, Deniz Simeone, Osvaldo Goldsmith, Andrea J. Poor, H. Vincent Shamai (Shitz), Shlomo Princeton Univ Dept Elect Engn Princeton NJ 08544 USA Stanford Univ Dept Elect Engn Stanford CA 94305 USA New Jersey Inst Technol CWCSPR Newark NJ 07102 USA Technion Israel Inst Technol Dept Elect Engn IL-32000 Haifa Israel

The problem of simultaneous multicasting of multiple messages with the help of a relay terminal is considered. In particular, a model is studied in which a relay station simultaneously assists two transmitters in multicasting their independent messages to two receivers. The relay may also have an independent message of its own to multicast. As a first step to address this general model, referred to as the compound multiple access channel with a relay (cMACr), the capacity region of the multiple access channel with a "cognitive" relay is characterized, including the cases of partial and rate-limited cognition. Then, achievable rate regions for the cMACr model are presented based on decode-and-forward (DF) and compress-and-forward (CF) relaying strategies. Moreover, an outer bound is derived for the special case, called the cMACr without cross-reception, in which each transmitter has a direct link to one of the receivers while the connection to the other receiver is enabled only through the relay terminal. The capacity region is characterized for a binary modulo additive cMACr without cross-reception, showing the optimality of binary linear block codes, and thus highlighting the benefits of physical layer network coding and structured codes. Results are extended to the Gaussian channel model as well, providing achievable rate regions for DF and CF, as well as for a structured code design based on lattice codes. It is shown that the performance with lattice codes approaches the upper bound for increasing power, surpassing the rates achieved by the considered random coding-based techniques.

关键词： Cognitive radio lattice coding multicasting network coding relay channel

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On the Gaussian multiway relay channel with intra-cluster links

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EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING 2016年第1期2016卷 1页

作者： Savard, Anne Weidmann, Claudio Univ Lille Telecom Lille CNRS UMR IEMN 8520 F-59000 Lille France Univ Cergy Pontoise CNRS ETIS ENSEA F-95014 Cergy Pontoise France

This paper studies the extension of the multiway relay channel (introduced by Gunduz et al.) by adding intra-cluster links. In this model, multiple clusters of users communicate with the help of one relay and the users within a cluster wish to exchange messages among themselves. Restricted encoders are considered;thus, the encoded messages of each user depend only on its own message, not on previously decoded ones. Cut-set bounds and achievable rates are given for the Gaussian case with and without time-sharing between clusters. Depending on the protocol considered, schemes based on random coding or nested lattice coding are proposed. The schemes are compared in terms of exchange capacity, that is the equal rate point in the capacity region of a symmetric multiway relay channel. It is shown that the gap between the cut-set bound and Compress-and-Forward, as well as Amplify-and-Forward, is independent of the transmit power constraints when time-sharing is used.

关键词： Relay channel Relaying protocols AWGN coding lattice coding

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Semantically Secure lattice Codes for Compound MIMO Channels

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IEEE TRANSACTIONS ON INFORMATION THEORY 2020年第3期66卷 1572-1584页

作者： Campello, Antonio Ling, Cong Belfiore, Jean-Claude Imperial Coll London Dept Elect & Elect Engn London SW7 2AZ England Huawei Technol Co Ltd France Res Ctr Math & Algorithm Sci Lab F-92100 Boulogne Billancourt France

We consider compound multi-input multi-output (MIMO) wiretap channels where minimal channel state information at the transmitter (CSIT) is assumed. Code construction is given for the special case of isotropic mutual information, which serves as a conservative strategy for general cases. Using the flatness factor for MIMO channels, we propose lattice codes universally achieving the secrecy capacity of compound MIMO wiretap channels up to a constant gap (measured in nats) that is equal to the number of transmit antennas. The proposed approach improves upon existing works on secrecy coding for MIMO wiretap channels from an error probability perspective, and establishes information theoretic security (in fact semantic security). We also give an algebraic construction to reduce the code design complexity, as well as the decoding complexity of the legitimate receiver. Thanks to the algebraic structures of number fields and division algebras, our code construction for compound MIMO wiretap channels can be reduced to that for Gaussian wiretap channels, up to some additional gap to secrecy capacity.

关键词： lattice coding information theoretic security semantic security compound channel

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A Hidden OSTBC Scheme to Enhance Physical Layer Security by Employing a Pseudorandom Precoder

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IEEE TRANSACTIONS ON COMMUNICATIONS 2020年第1期68卷 363-375页

作者： Sanandaji, Nader Falahati, Abolfazl Iran Univ Sci & Technol Dept Elect Engn Digital Coding & Cryptog Syst DCCS Lab Tehran 16844 Iran

The capability of exploiting Orthogonal Space-Time Block Codes (OSTBC) for increasing physical layer security of wireless systems is studied. A technique named "hidden OSTBC" is introduced, in which, a pseudorandom sequence is utilized by both transmitter and legitimate receiver to provide required security. Traditionally, employing pseudorandom sequences with methods such as spread spectrum or cooperative jamming involves huge amount of bandwidth or transmission power constraints, which are major challenges for wireless systems. Without requiring additional power or bandwidth, this study is designed to address exploitation of a pseudorandom antipodal sequence as a precoder. Elements of this sequence are multiplied to each antenna's transmitting symbol, and legitimate receiver employs the same sequence upon its combining rule. Mathematical analysis and simulations prove that an eavesdropper who does not know the pseudorandom sequence suffers from a degraded equivalent channel. Security enhancement is studied by investigating eavesdropper's higher error rate compared with that of legitimate receiver. Also, by employing lattice-based codebooks, a lower-bound is drawn for secrecy capacity, implying the achievability of nearly perfect secrecy regarding information theoretic analysis.

关键词： Physical layer security orthogonal space-time block code (OSTBC) symbol error rate lattice coding secrecy capacity

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AirCon: Over-the-Air Consensus for Wireless Blockchain Networks

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2024年第5期23卷 4566-4582页

作者： Xie, Xin Hua, Cunqing Hong, Jianan Gu, Pengwenlong Xu, Wenchao Shanghai Jiao Tong Univ Sch Cyber Sci & Engn Shanghai 200240 Peoples R China Inst Polytech Paris Telecom Paris Dept INFRES LTCI F-91120 Palaiseau France Hong Kong Polytech Univ Dept Comp Hong Kong Peoples R China

Blockchain has been deemed as a promising solution for providing security and privacy protection in the next-generation wireless networks. Large-scale concurrent access for massive wireless devices to accomplish the consensus procedure may consume prohibitive communication and computing resources, and thus may limit the application of blockchain in wireless conditions. As most existing consensus protocols are designed for wired networks, directly apply them for wireless users equipment (UEs) may exhaust their scarce spectrum and computing resources. In this paper, we propose AirCon, a byzantine fault-tolerant (BFT) consensus protocol for wireless UEs via the over-the-air computation. The novelty of AirCon is to take advantage of the intrinsic characteristic of the wireless channel and automatically achieve the consensus in the physical layer while receiving from the UEs, which greatly reduces the communication and computational cost that would be caused by traditional consensus protocols. We implement the AirCon protocol integrated into an LTE system and provide solutions to the critical issues for over-the-air consensus implementation. Experimental results are provided to show the feasibility of the proposed protocol, and simulation results to show the performance of the AirCon protocol under different wireless conditions.

关键词： Consensus protocol over-the-air computation wireless blockchain network lattice coding

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Zero-Delay Joint Source-Channel coding in the Presence of Interference Known at the Encoder

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IEEE TRANSACTIONS ON COMMUNICATIONS 2016年第8期64卷 3311-3322页

作者： Varasteh, Morteza Gunduz, Deniz Tuncel, Ertem Imperial Coll London Dept Elect & Elect Engn London SW7 2BZ England Univ Calif Santa Barbara Dept Elect & Comp Engn Santa Barbara CA 93106 USA

Zero-delay transmission of a Gaussian source over an additive white Gaussian noise (AWGN) channel is considered in the presence of an independent additive Gaussian interference signal. The mean squared error (MSE) distortion is minimized under an average power constraint assuming that the interference signal is known at the transmitter. Optimality of simple linear transmission does not hold in this setting due to the presence of the known interference signal. While the optimal encoder-decoder pair remains an open problem, various non-linear transmission schemes are proposed in this paper. In particular, interference concentration (ICO) and one-dimensional lattice (1DL) strategies, using both uniform and non-uniform quantization of the interference signal, are studied. It is shown that, in contrast to typical scalar quantization of Gaussian sources, a non-uniform quantizer, whose quantization intervals become smaller as we go further from zero, improves the performance. Given that the optimal decoder is the minimum MSE (MMSE) estimator, a necessary condition for the optimality of the encoder is derived, and the numerically optimized encoder (NOE) satisfying this condition is obtained. Based on the numerical results, it is shown that 1DL with non-uniform quantization performs closer (compared with the other schemes) to the NOE while requiring significantly lower complexity.

关键词： Interference concentration Joint source-channel coding lattice coding Zero-delay transmission

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Asymptotic Capacity of the Separated MIMO Two-Way Relay Channel

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IEEE TRANSACTIONS ON INFORMATION THEORY 2011年第11期57卷 7542-7554页

作者： Yang, Hyun Jong Chun, Joohwan Paulraj, Arogyaswami Korea Ocean Res & Dev Inst Taejon South Korea Korea Adv Inst Sci & Technol Dept Elect Engn Taejon 305701 South Korea Stanford Univ Dept Elect Engn Stanford CA 94305 USA

A multiple-input multiple-output two-way relay channel consisting of two communication nodes and a full-duplex relay node in which no direct link exists between the two communication nodes is considered. We propose an achievable scheme that employs horizontally encoded lattice codes combined with generalized singular value decomposition-based precoding for the first phase. The second phase of the proposed scheme follows the fundamentals of the previous scheme, which uses vertically encoded structural bining, with the only difference that the added codeword of the two codewords from the communication nodes, instead of those two individual codewords, is decoded and retransmitted in the proposed scheme. We show that the proposed scheme achieves the cut-set bound asymptotically as the signal-to-noise ratios of the channels tend to infinity.

关键词： Generalized singular value decomposition (GSVD) lattice coding linear precoding multiple-input multiple-output (MIMO) channels two-way relay channels (TWRC)

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Data Compression With Low Distortion and Finite Blocklength

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IEEE TRANSACTIONS ON INFORMATION THEORY 2017年第7期63卷 4268-4285页

作者： Kostina, Victoria CALTECH Pasadena CA 91125 USA

This paper considers lossy source coding of n-dimensional memoryless sources and shows an explicit approximation to the minimum source coding rate required to sustain the probability of exceeding distortion d no greater than epsilon, which is simpler than known dispersion-based approximations. Our approach takes inspiration in the celebrated classical result stating that the Shannon lower bound to rate-distortion function becomes tight in the limit d -> 0. We formulate an abstract version of the Shannon lower bound that recovers both the classical Shannon lower bound and the rate-distortion function itself as special cases. Likewise, we show that a nonasymptotic version of the abstract Shannon lower bound recovers all previously known nonasymptotic converses. A necessary and sufficient condition for the Shannon lower bound to be attained exactly is presented. It is demonstrated that whenever that condition is met, the rate-dispersion function is given simply by the varentropy of the source. Remarkably, all finite alphabet sources with balanced distortion measures satisfy that condition in the range of low distortions. Most continuous sources violate that condition. Still, we show that lattice quantizers closely approach the nonasymptotic Shannon lower bound, provided that the source density is smooth enough and the distortion is low. This implies that fine multidimensional lattice coverings are nearly optimal in the rate-distortion sense even at finite n. The achievability proof technique is based on a new bound on the output entropy of lattice quantizers in terms of the differential entropy of the source, the lattice cell size, and a smoothness parameter of the source density. The technique avoids both the usual random coding argument and the simplifying assumption of the presence of a dither signal.

关键词： Lossy source coding lattice coding rate-distortion function Shannon's lower bound low distortion high resolution finite blocklength regime dispersion rate-dispersion function nonasymptotic analysis

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On the Capacity Region of Asymmetric Gaussian Two-Way Line Channel

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IEEE TRANSACTIONS ON COMMUNICATIONS 2016年第9期64卷 3669-3682页

作者： Ghasemi-Goojani, Shahab Karimi-Bidhendi, Saeed Behroozi, Hamid Sharif Univ Technol Dept Elect Engn Tehran *** Iran

lattice codes are known to outperform random codes for certain networks, especially in the Gaussian two-way relay channels (GTWRCs) where lattice codes are able to exploit their linearity. As an extension of the GTWRC, in this paper, we consider the asymmetric Gaussian two-way line network where two nodes exchange their messages through multiple relays. We first investigate the capacity region of the full-duplex two-way two-relay line network. The results can be extended to an arbitrary number of relays and to half-duplex scenarios. This channel consists of four nodes: 1 <-> 2 <-> 3 <-> 4, where nodes 1 and 4 with the help of two full-duplex relays, i.e., nodes 2 and 3, exchange their messages with each other. Using lattice codes, we design a novel scheme that allows the relay nodes to send the data in both directions simultaneously under an asymmetric rate region. In the proposed scheme, each relay decodes the sum of lattice points and then re-encodes it into another lattice codeword (which satisfies the transmit power constraint at the relay). It is shown that the proposed scheme achieves the capacity region of asymmetric two-way line network within 0.5 bit independent of the number of relays.

关键词： lattice coding two-way line network two-way relay channel capacity region

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High-Dimensional Superposition NOMA and its User Pairing Strategy

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2021年第6期20卷 3800-3814页

作者： Zou, Jun Sung, Chi Wan Shum, Kenneth W. City Univ Hong Kong Dept Elect Engn Hong Kong Peoples R China Nanjing Univ Sci & Technol Sch Elect & Opt Engn Nanjing 210094 Peoples R China Chinese Univ Hong Kong Sch Sci & Engn Shenzhen Peoples R China

A novel power-domain non-orthogonal multiple access (NOMA) scheme with high-dimensional modulation is proposed. Signals for two users, each of which selected from a high-dimensional modulation constellation matrix, are superimposed on the same time-frequency resource for transmissions. While inter-user interference is treated as noise at the receiver of the far user, successive interference cancellation is used at the receiver of the near user. By analyzing the upper bounds of the detection errors, the power allocation factor is derived, which depends only on the relative power gain of the two users, i.e., the ratio between the squared of the two channel gains, but not on the operating signal-to-noise ratio. This nice feature allows us to perform user pairing easily for a system with more than two users. The optimal user pairing strategy that minimizes the total power consumption is analytically derived. Simulation results show that our proposed design outperforms some benchmark scheme.

关键词： lattices NOMA Modulation Resource management Error probability Quadrature amplitude modulation Constellation diagram Non-orthogonal multiple access (NOMA) lattice coding spherical coding superposition coding user pairing

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