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Power Allocation Strategies for distributed space-time codes in Two-Way Relay Networks

IEEE TRANSACTIONS ON SIGNAL PROCESSING 2010年第10期58卷 5331-5339页

作者： Wang, Wenjin Jin, Shi Gao, Xiqi Wong, Kai-Kit McKay, Matthew R. Southeast Univ Natl Mobile Commun Res Lab Sch Informat Sci & Engn Nanjing Peoples R China Southeast Univ Dept Radio Engn Nanjing 210018 Peoples R China UCL Dept Elect & Elect Engn London WC1E 7JE England Hong Kong Univ Sci & Technol Dept Elect & Comp Engn Ctr Wireless Informat Technol Kowloon Hong Kong Peoples R China

We study a two-way relay network (TWRN), where distributed space-time codes are constructed across multiple relay terminals in an amplify-and-forward mode. Each relay transmits a scaled linear combination of its received symbols and their conjugates, with the scaling factor chosen based on automatic gain control. We consider equal power allocation (EPA) across the relays, as well as the optimal power allocation (OPA) strategy given access to instantaneous channel state information (CSI). For EPA, we derive an upper bound on the pairwise-error-probability (PEP), from which we prove that full diversity is achieved in TWRNs. This result is in contrast to one-way relay networks, in which case a maximum diversity order of only unity can be obtained. When instantaneous CSI is available at the relays, we show that the OPA which minimizes the conditional PEP of the worse link can be cast as a generalized linear fractional program, which can be solved efficiently using the Dinkelback-type procedure. We also prove that, if the sum-power of the relay terminals is constrained, then the OPA will activate at most two relays.

关键词： distributed space-time codes power allocation two-way relay channel

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Asymptotic performance analysis of distributed space-time codes

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IEEE COMMUNICATIONS LETTERS 2006年第11期10卷 775-777页

作者： Uysal, Murat Canpolat, Onur Fareed, Muhammad Mehboob Univ Waterloo Dept Elect & Comp Engn Waterloo ON N2L 3G1 Canada

We study the asymptotic behavior of a cooperative scheme operating in amplify-and-forward (AF) mode for a large number of relays. An optimal code design rule is derived through the investigation of pairwise error probability (PEP) expression. The design rule turns out to be an Euclidean-distance-type metric including some scaling terms due to path loss and shadowing effects associated with underlying relay links and AF operation mode. Since the design criterion is channel dependent, it does not allow itself for a practical code design. However, we demonstrate that classical Euclidean distance can be used as a sub-optimal solution for realizing cooperative diversity advantages which we further verify through our simulation study.

关键词： distributed space-time codes cooperative diversity fading channels pairwise error probability

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Performance analysis of distributed space-time codes in amplify-and-forward mode

Performance analysis of distributed space-time codes in ampl...

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8th IEEE Workshop on Signal Processing Advances in Wireless Communications

作者： Maham, Behrouz Nader-Esfahani, Said Univ Tehran Sch ECE Tehran 14174 Iran Univ Oslo UniK Oslo Norway

ISBN: (纸本)9781424409549

The idea of space-time coding, devised for multiple-antenna systems, can be applied to communication over a wireless relay network in amplify-and-forward (AF) mode. In this paper, we propose a distributed space-time protocol in which source node contributes in transmitting information as a virtual relay, for a general R-relay system. This system does not require channel state information at relays. Our simulation results show that we get significant performance gain, when the source to destination link is also employed for transmitting information. Furthermore, assuming MPSK and MQAM modulation and maximum likelihood (ML) detection, we derive a formula for the bit error probability of the investigated schemes in Rayleigh fading channels. Our analytical results have been confirmed by simulation results, using full-rate, full-diversity distributed codes.

关键词： cooperation distributed space-time codes amplify-and-forward

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distributed GABBA space-time codes in Amplify-and-Forward Relay Networks

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2009年第4期8卷 2036-2045页

作者： Maham, Behrouz Hjorungnes, Are Abreu, Giuseppe Univ Oslo UNIK Univ Grad Ctr N-0316 Oslo Norway Univ Oulu Ctr Wireless Commun Oulu Finland

Cooperative communications via distributed space-time codes has been recently proposed as a way to form virtual multiple-antennas that provide dramatic gains in slow fading wireless environments. In this paper, we consider the design of practical distributed space-time codes for wireless relay networks using the amplify-and-forward (AF) scheme, where each relay transmits a scaled version of the linear combinations of the received symbols and their complex conjugate. We employ GABBA codes, which are systematically constructed, orthogonally decodable, full-rate, full-diversity space-time block codes, in a distributed fashion. Our scheme is valid for any number of relays with linear orthogonal decoding in the destination, which make it feasible to employ large numbers of potential relays to improve the diversity order. We generalize the distributed space-time codes in AF mode when the source-destination link contributes in both phases of the transmission. Assuming M-PSK or M-QAM constellations and maximum likelihood (ML) detection, we derive an approximate formula for the symbol error probability of the investigated scheme in Rayleigh fading channels. The analytical results are confirmed by simulations, indicating both the accuracy of the analysis, and the fact that low-complexity, flexible, and high-performing distributed space-time block codes can be designed based on GABBA codes.

关键词： Wireless relay network distributed space-time codes performance analysis cooperative communications

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Multigroup ML Decodable Collocated and distributed space-time Block codes

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IEEE TRANSACTIONS ON INFORMATION THEORY 2010年第7期56卷 3221-3247页

作者： Rajan, G. Susinder Rajan, B. Sundar Atheros India LLC Madras 600004 Tamil Nadu India Indian Inst Sci Dept Elect Commun Engn Bangalore 560012 Karnataka India

In this paper, collocated and distributed space-time block codes (DSTBCs) which admit multigroup maximum-likelihood (ML) decoding are studied. First, the collocated case is considered and the problem of constructing space-time block codes (STBCs) which optimally tradeoff rate and ML decoding complexity is posed. Recently, sufficient conditions for multigroup ML decodability have been provided in the literature and codes meeting these sufficient conditions were called Clifford unitary weight (CUW) STBCs. An algebraic framework based on extended Clifford algebras (ECAs) is proposed to study CUW STBCs and using this framework, the optimal tradeoff between rate and ML decoding complexity of CUW STBCs is obtained for few specific cases. Code constructions meeting this tradeoff optimally are also provided. The paper then focuses on multigroup ML decodable DSTBCs for application in synchronous wireless relay networks and three constructions of four-group ML decodable DSTBCs are provided. Finally, the orthogonal frequency-division multiplexing (OFDM)-based Alamouti space-time coded scheme proposed by Li-Xia for a 2-relay asynchronous relay network is extended to a more general transmission scheme that can achieve full asynchronous cooperative diversity for arbitrary number of relays. It is then shown how differential encoding at the source can be combined with the proposed transmission scheme to arrive at a new transmission scheme that can achieve full cooperative diversity in asynchronous wireless relay networks with no channel information and also no timing error knowledge at the destination node. Four-group decodable DSTBCs applicable in the proposed OFDM-based transmission scheme are also given.

关键词： Asynchronous cooperative communication Clifford algebra cooperative diversity decoding complexity distributed space-time codes orthogonal frequency-division multiplexing (OFDM) space-time codes

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distributed GABBA space-time codes in amplify-and-forward cooperation

Distributed GABBA space-time codes in amplify-and-forward co...

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IEEE Information Theory Workshop Information Theory for Wireless Networks

作者： Maham, Behrouz Hjorungnes, Are Univ Oslo UniK Univ Grad Ctr Oslo Norway

ISBN: (纸本)9781424411993

The idea of space-time coding, devised for multiple-antenna systems, can be applied to communication over a wireless relay network. This paper is on the design of practical distributed space-time codes for wireless relay networks, in which uses amplify-and-forward (AF) scheme in a way that each relay transmits a scaled version of linear combination of the received symbols. We use the recently presented GABBA codes, which are systematically constructed, orthogonally decodable, full-rate, full-diversity space-time block codes, in a distributed fashion. Our scheme is generalized to any number of relays with linear orthogonal decoding in the destination, which make it feasible to employ large number of potential relays to improve diversity order. Assuming BPSK modulation and maximum likelihood (ML) detection, we derive a formula for the bit error probability of the investigated scheme in Rayleigh fading channels. Our analytical results have been confirmed by simulation results, using full-rate, full-diversity distributed codes.

关键词： cooperation distributed space-time codes GABBA codes amplify-and-forward

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Fast Forced Symbol Method For distributed space-time Turbo codes Using Complex Orthogonal Design

Fast Forced Symbol Method For Distributed Space-Time Turbo C...

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17th IEEE Symposium on Computers and Communications (lSCC)

作者： Sattar, Zeeshan Ould-Cheikh-Mouhamedou, Youssouf Alsanie, Abdulhameed M. Behairy, Hatim M. King Saud Univ Dept Elect Engn Riyadh Saudi Arabia King Saud Univ PSATRI STC Chair Riyadh Saudi Arabia King Saud Univ Natl Elect Commun & Photon Res Program Riyadh Saudi Arabia King Saud Univ King Abdulaziz City Sci & Technol Riyadh Saudi Arabia

ISBN: (纸本)9781467327138

The idea of distributed space-time codes (DSTCs) was proposed to achieve spatial and temporal diversity without having channel information at the relays in wireless networks. In that scheme, distributive relays cooperate with each other to generate a space-time Code (STC) at the receiver. However, DSTCs have poor error rate performances at low signal to noise ratios (SNRs) that may disqualify them from being used in next generation mobile communications systems. To overcome this issue, this paper proposes a novel scheme based on the joint use of DSTCs and turbo codes, which we call "distributed space-time Turbo codes (DST-TCs)". We also propose a Fast Forced Symbol Method (FFSM) which significantly improves the coding gain of the proposed DST-TCs. The FFSM is based on repeated decoding operations and does not require any significant change in the design of encoder and decoder of DST-TC. The FFSM provides 0.9 dB of coding gain over simple DST-TC at frame error rate (FER) of 10(-5).

关键词： distributed space-time codes fast forced symbol method turbo codes repeated decoding

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Soft decode-and-forward cooperative communication with distributed space-time coding

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AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS 2013年第10期67卷 861-867页

作者： Huo, Peng Cao, Lei Univ Mississippi Dept Elect Engn Oxford MS 38677 USA

In existing soft decode-and-forward (SDF) cooperative communication systems, the source node is idling in the second time phase while the relay transmits the soft information. In fact, the source can transmit the hard information that cooperates with the relay's soft information using distributed space-time block codes (DSTBC). In this paper, we theoretically derive the detection performance in the second time phase by either using or not using the DSTBC based on the assumption that the soft information can be approximated by Gaussian distribution. This result also enables the optimal power allocation between the source and the relay in the second time phase. Finally, we show via simulation that the advantage of using DSTBC in the second time phase leads to the overall performance improvement of the coded cooperative system. Published by Elsevier GmbH.

关键词： distributed space-time codes Soft decode-and-forward (SDF) Coded cooperative system Turbo decoding

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Pairwise Error Probability of distributed space-time Coding Employing Alamouti Scheme in Wireless Relays Networks

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WIRELESS PERSONAL COMMUNICATIONS 2009年第2期51卷 231-244页

作者： Duong, Trung Q. Nguyen, Ngoc-Tien Hoang, Trang Nguyen, Viet-Kinh Blekinge Inst Technol S-37225 Ronneby Sweden MPT Hanoi Vietnam CEA LETI Heterogeneous Silicon Integrat Dept Grenoble France Hanoi Natl Univ Univ Technol Hanoi Vietnam

In this paper, we analyze the pairwise error probability (PEP) of distributed space-time codes, in which the source and the relay generate Alamouti space-time code in a distributed fashion. We restrict our attention to the space-time code construction for Protocol III in Nabar et al. (IEEE Journal on Selected Areas Communications 22(6): 1099-1109, 2004). In particular, we derive two closed-form approximations for PEP when the relay is either close to the destination or source and an upper bound for any position of the relay. Using the alternative definition of Q-function, we can express these PEPs in terms of finite integral whose integrand is composed of trigonometric functions. We further show that with only one relay assisted source-destination link, system still achieves diversity order of two, assuming single-antenna terminals. We also perform Monte-Carlo simulations to verify the analysis.

关键词： distributed space-time codes Relay channels Pairwise error probability (PEP)

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Non-orthogonal Amplify and Forward Relay Selection Systems with distributed space-time Trellis Coded Continuous Phase Modulation

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WIRELESS PERSONAL COMMUNICATIONS 2015年第2期84卷 1209-1225页

作者： Demiroglu, Ali Serdar Altunbas, Ibrahim Celebi, Mehmet E. Istanbul Tech Univ Elect & Commun Engn Dept TR-34469 Istanbul Turkey Netas Headquarters TR-34912 Istanbul Turkey

Most of the works on cooperative systems with or without relay selection have focused on linear modulations such as phase shift keying and quadrature amplitude modulation. Whereas, continuous phase modulation (CPM) is a good alternative to these modulations due to its constant envelope property which enables us to use inexpensive and energy-efficient non-linear power amplifiers. In the literature, a few works are based on relaying systems with CPM. To the best of our knowledge, none exists with relay selection. In this paper, we propose single and multiple relay selection CPM schemes based on a new generalized relay selection criterion for non-orthogonal amplify and forward (AF) systems operating with various time sharing protocols. In particular, using the proposed criterion, the best relay or the best two relays over a set of four available relays is/are selected. Error performances of the non-orthogonal AF relay selection systems and their counterparts are compared over frequency non-selective quasi-static Rayleigh fading channels using Viterbi algorithm at the destination terminal. Our numerical results present superiority of the proposed non-orthogonal relay selection systems.

关键词： Relay selection Continuous phase modulation Non-orthogonal amplify and forward relaying distributed space-time codes Cooperative communications

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