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Analysis and design of distributed space-time trellis codes with amplify-and-forward relaying

IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2007年第4期56卷 1649-1660页

作者： Canpolat, Onur Uysal, Murat Fareed, Muhammad Mehboob Univ Waterloo Dept Elect & Comp Engn Waterloo ON N2L 3G1 Canada RIM Waterloo ON N2L 3W8 Canada

We study the asymptotic behavior of a cooperative scheme operating in amplify-and-forward (AF) mode when the number of relay terminals tends to infinity. We consider three time-division-multiple-access-based cooperation protocols which realize different degrees of broadcasting and receive collision. Optimal design rules for distributed space-time codes (STCs) are derived through the investigation of pairwise error probability expression for each considered protocol. The derived design rules reveal a Euclidean-distance-type performance metric, including some scaling terms due to the effects of AF operation mode and cooperation protocols as well as path loss/shadowing effects associated with the underlying relay links. Based on the derived criteria, an exhaustive computer code search is conducted to find out optimal distributed STCs. Our search results indicate the optimality of conventional designs, i.e., based on classical Euclidean distance, for relay numbers larger than two in a distributed scenario. For the special cases of one and two relays, we present novel distributed codes which are able to outperform their conventional counterparts and demonstrate robustness against distributed implementation.

关键词： amplify-and-forward (AF) relaying cooperative diversity distributed space-time coding pairwise error probability (PEP)

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distributed space-time Codes Using Constellation Rotation

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WIRELESS PERSONAL COMMUNICATIONS 2011年第1期61卷 161-177页

作者： Zhang, Chao Wang, Weidong Wei, Guo Univ Sci & Technol China Dept Elect Engn & Informat Sci Wireless Informat Network Lab Hefei 230026 Peoples R China

Rate and diversity impose a fundamental tradeoff in wireless communication. We propose a novel distributed space-time coding (DSTC) scheme based on constellation rotation (DSTC-CR) for Amplify-and-Forward relay networks. The proposed code can achieve full-diversity or full-rate, and also offers a flexibility for a desired rate-diversity tradeoff. This code can work well with arbitrary signal constellation and any number of relays and achieve minimal-delay. Through analysis of pairwise error probability, coding design criteria, Chernoff bound, decoding strategies and optimal power allocation are provided. Simulation results show that DSTC-CR scheme outperforms diagonal DSTC (DDSTC) and distributed linear dispersion (DLD) code at high power. From the comparison with DDSTC, the DSTC-CR scheme can achieve the same information rate using a lower modulation order.

关键词： distributed space-time coding Relay Cooperative network

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Do Cooperative Radios Collide?

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IEEE TRANSACTIONS ON COMMUNICATIONS 2012年第4期60卷 1020-1032页

作者： Rueetschi, Andrea Scaglione, Anna Univ Calif Davis Dept Elect & Comp Engn Davis CA 95616 USA Philips Semicond Zurich Switzerland Philips Semicond San Jose CA USA Cornell Univ Ithaca NY USA

When cooperative terminals transmit concurrently, the receiver experiences additional distortion by the presence of radios carrier offsets and time delays. With the inevitable inaccuracy in estimating the channel at the receiving end, is it realistic to assume that relays transmissions do not collide? To address this question, we provide an analytical framework to model the effect of channel estimation methods that treat the channel as deterministic and unknown, and derive the average symbol error rate (SER) of a maximum likelihood sequence decoder (MLSD) and of a linear minimum mean squared error (LMMSE) equalizer using such estimates. We select the appropriate architecture by mapping two different channel estimation techniques onto the proposed analytical framework, and derive their diversity gain. First we analyze the well known linear least square channel estimation (LLSE), then, we show how to cast a compressed channel sensing (CCS) method onto our analytical model, by a novel approximation of the estimator noise and modeling mismatch. We observe that the latter is the key bottleneck in LLSE whereas the CCS appears sufficiently flexible to deliver the promised gains. This conclusion shows that collisions models are overly pessimistic, but it also underscores the need for an advanced receiver synchronization design.

关键词： Cooperative communication channel estimation diversity distributed space-time coding

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Relay Power Allocation in distributed space-time Coded Networks with Channel Statistical Information

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2011年第2期10卷 443-449页

作者： Jing, Yindi Jafarkhani, Hamid Univ Alberta Dept Elect & Comp Engn Edmonton AB T6G 2V4 Canada Univ Calif Irvine Ctr Pervas Commun & Comp Irvine CA 92697 USA

This letter considers two-relay networks with Rician fading channels. It is assumed that the receiver has full channel information while the relays know the channel means and covariances only. To optimize network performance, we combine distributed space-time coding (DSTC) with relay power allocation. For the high signal-to-noise ratio (SNR) regime, we analytically find the relay power allocation that minimizes an upper bound on the pairwise error probability (PEP). Simulation shows that the proposed scheme largely improves network reliability. In some cases, lack of power allocation causes diversity loss.

关键词： Power allocation distributed space-time coding partial channel state information pairwise error probability Rician fading

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Novel distributed space-time Trellis Codes for Relay Systems over Cascaded Rayleigh Fading

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IEEE COMMUNICATIONS LETTERS 2010年第12期14卷 1140-1142页

作者： Ilhan, Haci Altunbas, Ibrahim Uysal, Murat Istanbul Tech Univ Dept Elect & Commun Engn TR-34469 Istanbul Turkey Ozyegin Univ Fac Engn TR-34662 Istanbul Turkey

In this letter, we consider the deployment of distributed space-time trellis codes (STTCs) for user cooperation. We derive a pairwise error probability (PEP) expression for distributed STTCs over cascaded Rayleigh fading channels. Using the derived PEP expression, we determine a code design criterion and propose novel 4-/8-/16-state 4-PSK and 8-/16-state 8-PSK distributed STTCs through a systematic code search. We confirm the superiority of the proposed codes through extensive Monte-Carlo simulations.

关键词： Error rate performance distributed space-time coding amplify-and-forward relaying cascaded Rayleigh fading channels

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Optimization of Linear Dispersion Codes for Wireless Relay Networks

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IEEE SIGNAL PROCESSING LETTERS 2009年第5期16卷 366-369页

作者： Nguyen, Ha X. Nguyen, Ha H. Le-Ngoc, Tho Univ Saskatchewan Dept Elect Engn Saskatoon SK S7N 5A9 Canada McGill Univ Dept Elect & Comp Engn Montreal PQ H3A 2A7 Canada

A design method is introduced for linear dispersion (LD) space-time codes in wireless relay networks under Rayleigh fading channels. The codes are designed with a stochastic quasi-gradient algorithm to minimize the upper bound of the average pairwise error probability. Simulation results show that the optimized codes achieve a coding gain of about 2 dB over codes that are randomly generated based on the isotropic distribution.

关键词： coding gain distributed space-time coding pair-wise error probability (PEP) relay networks stochastic optimization

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Training-Symbol Embedded, High-Rate, Single-Symbol ML-Decodable, distributed STBCs for Relay Networks

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IEEE TRANSACTIONS ON INFORMATION THEORY 2011年第9期57卷 6157-6169页

作者： Harshan, J. Rajan, B. Sundar Hjorungnes, Are Indian Inst Sci Dept Elect Commun Engn Bangalore 560012 Karnataka India Univ Oslo UNIK Univ Grad Ctr N-0313 Oslo Norway

distributed space-time block codes (DSTBCs) from complex orthogonal designs (CODs) (both square and nonsquare), coordinate interleaved orthogonal designs (CIODs), and Clifford unitary weight designs (CUWDs) are known to lose their single-symbol ML decodable (SSD) property when used in two-hop wireless relay networks using amplify and forward protocol. For such networks, in this paper, three new classes of high rate, training-symbol embedded (TSE) SSD DSTBCs are constructed: TSE-CODs, TSE-CIODs, and TSE-CUWDs. The proposed codes include the training symbols inside the structure of the code which is shown to be the key point to obtain the SSD property along with the channel estimation capability. TSE-CODs are shown to offer full-diversity for arbitrary complex constellations and the constellations for which TSE-CIODs and TSE-CUWDs offer full-diversity are characterized. It is shown that DSTBCs from nonsquare TSE-CODs provide better rates (in symbols per channel use) when compared to the known SSD DSTBCs for relay networks. Important from the practical point of view, the proposed DSTBCs do not contain any zeros in their codewords and as a result, antennas of the relay nodes do not undergo a sequence of switch on/off transitions within every codeword, and, thus, avoid the antenna switching problem.

关键词： Complex orthogonal designs cooperative diversity distributed space-time coding single-symbol ML decoding

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High-Rate, Single-Symbol ML Decodable Precoded DSTBCs for Cooperative Networks

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IEEE TRANSACTIONS ON INFORMATION THEORY 2009年第5期55卷 2004-2015页

作者： Harshan, J. Rajan, B. Sundar Indian Inst Sci Dept Elect Commun Engn Bangalore 560012 Karnataka India

distributed orthogonal space-time block codes (DOSTBCs) achieving full-diversity order and single-symbol maximum-likelihood (ML) decodability have been introduced recently by Yi and Kim for cooperative networks, and an upper bound on the maximal rate of such codes along with code constructions has been presented. In this paper, a new class of single-symbol ML decodable precoded distributed space-time block codes (SSD-PDSTBCs) called semiorthogonal SSD-PDSTBCs (semi-SSD-PDSTBCs) is introduced wherein, the source performs linear precoding of information symbols appropriately before transmitting it to all the relays. It is shown that DOSTBCs are a special case of semi-SSD-PDSTBCs. A special class of semi-SSD-PDSTBCs having diagonal covariance matrix at the destination is studied and an upper bound on the maximal rate of such codes is derived. The bounds obtained are approximately twice larger than that of the DOSTBCs. A systematic construction of semi-SSD-PDSTBCs is presented when the number of relays K >= 4. The constructed codes are shown to achieve the upper bound on the rate when K is of the form 0 or 3 modulo 4. For the rest of the values of K, the constructed codes are shown to have rates higher than that of DOSTBCs. It is shown that semi-SSD-PDSTBCs cannot be constructed with any form of linear processing at the relays when the source does not perform linear precoding of the information symbols.

关键词： Cooperative diversity distributed space-time coding precoding single-symbol maximum-likelihood (ML) decoding

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Cyclic distributed space-time Codes for Wireless Relay Networks With No Channel Information

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IEEE TRANSACTIONS ON INFORMATION THEORY 2010年第1期56卷 250-265页

作者： Oggier, Frederique Hassibi, Babak CALTECH Dept Elect Engn Pasadena CA 91125 USA

In this paper, we present a coding strategy for half duplex wireless relay networks, where we assume no channel knowledge at any of the transmitter, receiver, or relays. The coding scheme uses distributed space-time coding, that is, the relay nodes cooperate to encode the transmitted signal so that the receiver senses a space-time codeword. It is inspired by noncoherent differential techniques. The proposed strategy is available for any number of relays nodes. It is analyzed, and shown to yield a diversity linear in the number of relays. We also study the resistance of the scheme to relay node failures, and show that a network with relay nodes and d of them down behaves, as far as diversity is concerned, as a network with R - d nodes. Finally, our construction can be easily generalized to the case where the transmitter and receiver nodes have several antennas.

关键词： Differential modulation distributed space-time coding noncoherent multiple-input multiple-output (MIMO) channels

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Outage probability in distributed transmission based on best relay pair selection

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IET COMMUNICATIONS 2012年第12期6卷 1829-1836页

作者： Chen, G. Chambers, J. Univ Loughborough Adv Signal Proc Grp Loughborough Leics England

Cooperative diversity has been recently proposed as a way to form virtual antenna arrays and thereby mitigate the deleterious effect of fading channels in transmission. In an environment where multiple relays are available, selection of a subset of such relays may be required as, for example, in distributed space-time coding. In this study, the authors therefore use local measurements of the instantaneous channel conditions to select the best relay pair from a set of N available relays, which both come from the same cluster or different clusters, and then use these best relays for cooperation between the source and the destination. The authors also show that the best relay pair selection scheme has robustness against feedback error and outperforms a scheme based on selecting only the best single relay. The authors obtain analytical expressions for the probability density function, cumulative density function and the moment generating function of the received signal-to-noise ratio to derive closed-form expressions for outage probability over Rayleigh frequency flat-fading channels. The analytical results are supported by simulation studies.

关键词： moment generating function local measurements space-time codes Codes probability closed-form expressions cooperative communication robustness distributed transmission diversity reception distributed space-time coding feedback error cooperative diversity received signal- to-noise ratio antenna arrays Antenna arrays cumulative density function virtual antenna arrays probability density function Rayleigh frequency flat-fading channel Radio links and equipment outage probability Rayleigh channels best relay pair selection Other topics in statistics

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