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Compressed Relaying for Two-Way Relay networks With Correlated Sources

IEEE WIRELESS COMMUNICATIONS LETTERS 2015年第1期4卷 30-33页

作者： Huo, Qiang Yang, Kun Song, Lingyang Li, Yonghui Jiao, Bingli Huawei Technol Co Ltd Phys Layer & RRM IC Algorithm Dept Shanghai Res Ctr Shanghai 201206 Peoples R China Peking Univ Sch Elect Engn & Comp Sci Beijing 100871 Peoples R China Univ Sydney Sch Elect & Informat Engn Sydney NSW 2006 Australia

In this letter, a compressed relaying scheme via Huffman and physical-layer network coding (HPNC) is proposed for two-way relay networks with correlated sources (TWRN-CS). In the HPNC scheme, both sources first transmit the correlated raw source messages to the relay simultaneously. The relay performs physical-layer network coding (PNC) on the received symbols, compresses the PNC-coded symbols using Huffman coding, and broadcasts the compressed symbols to both source nodes. Then, each source decodes the other source's messages by using its own messages as side information. Compression rate and block error rate (BLER) of the proposed scheme are analyzed. Simulation results demonstrate that the HPNC scheme can effectively improve the network throughput, and meanwhile, achieve the superior BLER performance compared with the conventional non-compressed relaying scheme in TWRN-CS.

关键词： Compression correlated bidirectional relay networks Huffman coding physical-layer network coding

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network-Coded Multiple Access II: Toward Real-Time Operation With Improved Performance

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2015年第2期33卷 264-280页

作者： You, Lizhao Liew, Soung Chang Lu, Lu Chinese Univ Hong Kong Dept Informat Engn Shatin Hong Kong Peoples R China Chinese Univ Hong Kong Inst Network Coding Shatin Hong Kong Peoples R China

This paper presents a first real-time network-coded multiple access (NCMA) system that jointly exploits physical (PHY)-layer network coding (PNC) and multiuser decoding (MUD) to boost the throughput of a wireless local area network (WLAN). NCMA is a new design paradigm for multipacket reception wireless networks, in which the access point can receive and decode several packets simultaneously transmitted by multiple users. Conventionally, multipacket reception is realized using MUD only, whereas the key idea of NCMA is to use PNC together with MUD to realize multipacket reception. Although the feasibility of NCMA has previously been studied by the authors, our previous NCMA prototype was a version with offline signal processing. In addition, our previous investigation left open a number of theoretical and implementation issues, the resolution of which is critical to the adoption of NCMA in real practice. The current investigation makes the following state-of-the-art contributions toward NCMA: 1) we demonstrate a first NCMA system with integrated real-time PHY- and MAC-layer decoding;2) we construct a new unified framework for MAC-layer decoding that yields higher throughput with faster decoding-the faster decoding is one of the key enablers of our real-time implementation;and 3) we design new PHY-layer decoding techniques that overcome the poor performance of the first-generation NCMA prototype at low SNR. Experimental results show that, compared with the previous NCMA prototype, our new NCMA prototype improves real-time throughput by more than 100% at medium-high SNR (>= 8 dB).

关键词： network coding physical-layer network coding multiuser detection multiple access network-coded multiple access implementation

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Full-duplex MIMO and PLNC for the Y-network

Full-duplex MIMO and PLNC for the Y-network

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Mediterranean Electrotechnical Conference (MELECON)

作者： Filipe E. Ferreira Francisco A. Monteiro Ivo Sousa Instituto de Telecomunicações Portugal ISCTE - Instituto Universitário de Lisboa Portugal Instituto Superior Técnico Universidade de Lisboa Portugal

ISBN: (纸本)9781509000593

This paper considers a multi-way wireless network with three terminals which want to exchange or share data with the help of a relay: each terminal has some information that wants to transmit to the other two. The traditional way of doing this exchange either involves time-domain multiplexing (TDMA) or dedicated frequency-domain disjoint channels, at the expense of high bandwidth inefficiency. With the advent of network coding, and later physical-layer network coding, it became possible to reduce the number of time slots required to exchange the information between all the terminals. Moreover, using multiple-input multiple-output (MIMO) terminals and relays, the time-usage efficiency can be further boosted by transferring the burden from the time-domain to the spatial-domain via spatial multiplexing. This paper proposes the concatenation of the aforementioned techniques along with loopback interference cancellation, which recently became a central topic for the next generation of the physical-layer of wireless communications. The paper shows a protocol and techniques that allow all the information exchange between terminals to be reduced from the 6 time-slots, required in traditional TDMA, to one time-slot only, provided that the information packets are not too short. The error performance of this system is shown by means of simulation using MIMO Rayleigh fading channels.

关键词： MIMO Multi-way channel full-duplex interference suppression physical-layer network coding FULL DUPLEX multiple input multiple output systems suppression of interference physical layer information exchange network coding Device Terminal error performance

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Node Symbol Timing Error Estimator for physical-layer network-Coded Relay

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2015年第12期E98A卷 2733-2737页

作者： Dang, Xiaoyu Li, Qiang Xiao, Hao Wan, Cheng Nanjing Univ Aeronaut & Astronaut Dept Elect Informat Engn Nanjing Jiangsu Peoples R China

network coding on the physical-layer has recently been widely discussed as a potentially promising solution to the wireless access problem in a relay network. However, the existing research on physical-layer network coding (PNC), usually assumes that the symbol timing of the nodes is fully synchronized and hardly investigates the unavoidable symbol timing errors. Similar to many telecommunication systems, symbol timing plays a critical role in PNC and precise alignment has to be provided for the encoding. In this work, we propose a novel symbol timing algorithm with a low oversampling factor (samples per symbol) based on the a priori knowledge of the transmitted pulse shape. The proposed algorithm has the dual advantages of the low oversampling rate and high precision. The mean square error (MSE) performance is verified by simulations to be at least one order of magnitude better than that of the conventional optimum phase (OP) algorithm for a signal noise ratio (SNR) greater than 5 dB.

关键词： physical-layer network coding two-way relay channels symbol timing estimation pulse shape

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Efficient Decoding Algorithms for the Compute-and-Forward Strategy

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IEEE TRANSACTIONS ON COMMUNICATIONS 2015年第7期63卷 2475-2485页

作者： Mejri, Asma Rekaya-Ben Othman, Ghaya Telecom ParisTech Dept Commun & Elect F-75013 Paris France

We address in this paper decoding aspects of the Compute-and-Forward (CF) physical-layer network coding strategy. Under the CF framework, encoders use a special class of nested lattice codes and decoders are based on suboptimal minimum distance decoding of unknown performance gap with respect to optimal decoders. In this work, we develop and assess the performance of novel decoding algorithms for CF operating in the multiple access channel. Starting with the Gaussian channel, we investigate the maximum a posteriori (MAP) decoder. We derive a novel MAP decoding metric and develop practical decoding algorithms shown numerically to outperform the original one. For the fading channel, we analyze the ML decoder for integer-valued lattices and develop a novel Diophantine approximation-based near-ML decoding algorithm shown numerically to outperform the original CF decoder in the 1-D case using Z lattices.

关键词： physical-layer network coding compute-and-forward lattice decoding maximum a posteriori decoding

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A Comparative Analysis of Secrecy Rates of Wireless Two-Way Relay Systems 58

A Comparative Analysis of Secrecy Rates of Wireless Two-Way ...

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IEEE Global Telecommunications Conference (GLOBECOM)

作者： Chang, Chih-Hua Chang, Ronald Y. Huang, Yu-Chih Purdue Univ Sch Elect & Comp Engn W Lafayette IN 47907 USA Acad Sinica Res Ctr Informat Technol Innovat Taipei Taiwan Natl Taipei Univ Dept Commun Engn New Taipei 23741 Taiwan

ISBN: (纸本)9781479959525

This paper studies the information-theoretic secrecy rates of wireless two-way relay systems where two users wish to exchange information through a single relay with an eavesdropper observing all communications. We formulate and compare the achievable secrecy rates of the system that employs one of the three common relay protocols: conventional decode-and-forward (DF), DF with network coding (NC), and compute-and-forward (CF) based on physical-layer network coding (PNC). We show that CF based on PNC achieves the highest secrecy rate at high signal-to-noise ratio (SNR), while, interestingly, the other two protocols have mixed performance depending on the power allocation scheme and network topology. Our study offers insights into designing wireless two-way relay protocols from a secrecy perspective.

关键词： Two-way relaying information-theoretic security physical-layer security network coding physical-layer network coding

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Wireless MIMO Switching with Trusted and Untrusted Relays: Degrees of Freedom Perspective

Wireless MIMO Switching with Trusted and Untrusted Relays: D...

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IEEE International Conference on Communications (ICC)

作者： Wang, Fanggang Yuan, Xiaojun Lee, Jemin Quek, Tony Q. S. Beijing Jiaotong Univ State Key Lab Rail Traff Control & Safety Beijing Peoples R China ShanghaiTech Univ Sch Informat Sci & Technol Shanghai Peoples R China Singapore Univ Technol & Design Singapore Singapore

ISBN: (纸本)9781467364324

We investigate the degrees of freedom (DoF) and secrecy DoF for a general framework of multiway relay networks named wireless MIMO switching, where a number of users exchange information via a common relay. Each round of data exchange consists of one uplink transmission from users to relay and one downlink transmission from relay back to users. The data exchange model is unicast, i.e., every user transmits one message and intends to receive one message from one other user. We categorize unicast patterns using the notion of orbit borrowed from abstract algebra. Roughly speaking, an orbit is a minimum subset of users such that data exchange is closed within this subset. We analyze the achievable DoF of wireless MIMO switching with various numbers of orbits. Particularly, the DoF capacity for unicast with one and two orbits are established. Furthermore, we study communication secrecy with an untrusted relay in wireless MIMO switching. We present an achievable secrecy sum rate and the corresponding achievable secrecy DoF by assuming a non-regenerative relay. Then, we focus on unicast patterns with one and two orbits, and show that this achievable lower bound is actually the secrecy DoF capacity based on a novel genie-aided technique. Our results build a bridge between the DoF and the secrecy DoF in multiway relaying. The methodology of the proof can be generally applied to analyze the secrecy DoF in other relay networks.

关键词： Degrees of freedom MIMO switching physical-layer network coding multiway relay secrecy sum rate

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Joint Signal and Interference Alignment in Two-Way Relay Communications 81

Joint Signal and Interference Alignment in Two-Way Relay Com...

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81st IEEE Vehicular Technology Conference (VTC Spring)

作者： Liang, Yao-Jen Chen, Hsin-Jung Natl Chiayi Univ Dept Elect Engn Chiayi 60004 Taiwan Natl Taiwan Univ Grad Inst Commun Engn Taipei 10764 Taiwan

ISBN: (纸本)9781479980888

In this paper, we study the application of physical layer network coding (PNC) and interference alignment scheme to the joint design of uplink and downlink transmissions, where the base station (BS), the mobile stations (MSs) and the relays all have multiple antennas. Leveraging from the interference alignment and physical-layer network coding, a joint signal and interference alignment scheme is proposed, where uplink and downlink communications can be accomplished within two time slots. Since here two relays share the same spectrum to assist the data transmission, co-channel interference (CI) would be induced and the communication reliability would be deteriorated. To address this challenge, precoding matrices at the BS, the MSs, and relays have been carefully designed to ensure the removal of CI. Additionally, the received signals from BS and MSs are mixed and broadcasted to BS and MSs at the next time duration. Simulation results also demonstrate the performance of the proposed joint signal and interference alignment scheme.

关键词： cellular system two-way relay channel physical-layer network coding interference alignment

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Lattice network Codes over Optimal Lattices in Low Dimensions 7

Lattice Network Codes over Optimal Lattices in Low Dimension...

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7th International Workshop on Signal Design and Its Applications in Communications

作者： Shum, Kenneth W. Sun, Qifu Tyler Chinese Univ Hong Kong Inst Network Coding Hong Kong Hong Kong Peoples R China Univ Sci & Technol Sch Comp & Commun Engn Beijing Peoples R China

ISBN: (纸本)9781467383080

Lattice network coding is an important building block of physical-layer network coding. The receiver is required to compute a linear combination of the source symbols belonging to a finite alphabet with an algebraic structure. In this paper, lattice network codes are constructed from lattices that have optimal packing density and the best known shaping gain in low dimensions. Using the efficient quantization functions of these optimallattices, practical lattice network codes are constructed. Simulation results demonstrate that there is a 4 to 5 dB performance gain in comparison to the baseline lattice network code with hyper-cube shaping.

关键词： physical-layer network coding lattice network codes Gosset lattice

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Outage Approaching Turbo-network Codes for the Multiple-Access Relay Channel

Outage Approaching Turbo-Network Codes for the Multiple-Acce...

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International Conference on Communications Management and Telecommunications ComManTel

作者： Kraidy, Ghassan M. Notre Dame Univ Louaize ECCE Dept POB 72 Zouk Mikael Lebanon

ISBN: (纸本)9781467365475

In this work, we propose the construction of distributed turbo network codes that have close-to-outage probability performance over the quasi-static fading multiple-access relay (MARC) channel, where two users share a common relay to transmit their information to the destination. Our designs are based on full-diversity channel multiplexing schemes initially developed for point-to-point block fading channels, namely horizontal multiplexing and h-pi-diagonal multiplexing. Word error rate performance is compared to outage probability using Monte Carlo simulations.

关键词： Turbo codes physical-layer network coding multiple-access relay channel quasi-static fading channel

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