Distributed space-time block coding in wireless cooperative communications.

Cheng Ho Ting.Thesis (M.Phil.)--Chinese University of Hong Kong, 2005.Includes bibliographical references (leaves 90-93).Abstracts in English and Chinese.Abstract --- p.iAcknowledgement --- p.ivChapter 1 --- Introduction --- p.1Chapter 1.1 --- Overview of Wireless Cooperative Communications --- p.1Chapter 1.2 --- Motivation --- p.2Chapter 1.3 --- Distributed Space-Time Block Coding --- p.4Chapter 1.4 --- Imperfect Channel Estimation --- p.4Chapter 1.5 --- Time-Varying Channels --- p.4Chapter 1.6 --- Outline of the thesis --- p.5Chapter 2 --- Background Study --- p.6Chapter 3 --- Distributed Space-Time Block Coding --- p.13Chapter 3.1 --- Introduction --- p.13Chapter 3.2 --- System Model --- p.13Chapter 3.3 --- BER Analysis by Characteristic Equations --- p.16Chapter 3.4 --- BER Analysis by Error Terms --- p.18Chapter 3.4.1 --- Non-fading R→D link --- p.19Chapter 3.4.2 --- Fading R→D link --- p.19Chapter 3.5 --- Performance --- p.20Chapter 3.5.1 --- Accuracy of Analytical Expressions --- p.20Chapter 3.5.2 --- Observation of Second-order Diversity --- p.21Chapter 3.6 --- Summary --- p.22Chapter 4 --- Distributed Space-Time Block Coding with Imperfect Channel Estimation --- p.31Chapter 4.1 --- Introduction --- p.31Chapter 4.2 --- System Model --- p.32Chapter 4.3 --- BER Analysis --- p.32Chapter 4.3.1 --- Non-fading R→D link --- p.33Chapter 4.3.2 --- Fading R→D link --- p.34Chapter 4.4 --- Numerical Results --- p.34Chapter 4.5 --- Summary --- p.36Chapter 5 --- Distributed Space-Time Block Coding with Time-Varying Channels --- p.43Chapter 5.1 --- Introduction --- p.43Chapter 5.2 --- System Model --- p.44Chapter 5.3 --- Pilot Symbol Assisted Modulation (PSAM) for DSTBC --- p.45Chapter 5.4 --- Reception Methods --- p.48Chapter 5.4.1 --- Maximum-Likelihood Detection (ML) in [29] --- p.48Chapter 5.4.2 --- Cooperative Maximum-Likelihood Detection (CML) --- p.50Chapter 5.4.3 --- Alamouti's Receiver (AR) --- p.51Chapter 5.4.4 --- Zero-forcing Linear Detection (ZF) --- p.51Chapter 5.4.5 --- Decision-feedback Detection (DF) --- p.52Chapter 5.5 --- BER Analysis for Time-varying Channels --- p.53Chapter 5.5.1 --- Quasi-Static Channels (p = 1) --- p.53Chapter 5.5.2 --- ZF: Uncorrelated Channel (p = 0) --- p.54Chapter 5.5.3 --- ZF: General Channel --- p.55Chapter 5.5.4 --- DF: General Channel --- p.56Chapter 5.6 --- Numerical Results --- p.57Chapter 5.7 --- Summary --- p.60Chapter 6 --- Conclusion and Future Work --- p.74Chapter 6.1 --- Conclusion --- p.74Chapter 6.2 --- Future Work --- p.76Chapter 6.2.1 --- Design of Code Matrix --- p.76Chapter 6.2.2 --- Adaptive Protocols --- p.77Chapter A --- Derivation of (3.23) --- p.79Chapter B --- Derivation of (3.30) and (3.32) --- p.83Chapter C --- Derivation of (4.9) and (4.13) --- p.85Chapter D --- Derivation of (5.68) --- p.88Bibliography --- p.9

Distributed space time block coding in asynchronous cooperative relay networks

The design and analysis of various distributed space time block coding schemes for asynchronous cooperative relay networks is considered in this thesis. Rayleigh frequency flat fading channels are assumed to model the links in the networks, and interference suppression techniques together with an orthogonal frequency division multiplexing type transmission approach are employed to mitigate the synchronization errors at the destination node induced by the different delays through the relay nodes. Closed-loop space time block coding is first considered in the context of decode-and-forward (regenerative) networks. In particular, quasi orthogonal and extended orthogonal coding techniques are employed for transmission from four relay nodes and parallel interference cancellation detection is exploited to mitigate synchronization errors. Availability of a direct link between the source and destination nodes is studied, and a new Alamouti space time block coding technique with parallel interference cancellation detection which does not require such a direct link connection and employs two relay nodes is proposed. Outer coding is then added to gain further improvement in end-to-end performance and amplify-and-forward (non regenerative) type networks together with distributed space time coding are considered to reduce relay node complexity. Novel detection schemes are then proposed for decode-and-forward networks with closed-loop extended orthogonal coding which reduce the computational complexity of the parallel interference cancellation. Both sub-optimum and near-optimum detectors are presented for relay nodes with single or dual antennas. End-to-end bit error rate simulations confirm the potential of the approaches and their ability to mitigate synchronization errors. A relay selection approach is also formulated which maximizes spatial diversity gain and attains robustness to timing errors. Finally, a new closed-loop distributed extended orthogonal space time block coding solution for amplify-and-forward type networks which minimizes the number of feedback bits by using a cyclic rotation phase is presented. This approach utilizes an orthogonal frequency division multiplexing type transmission structure with a cyclic prefix to mitigate synchronization errors. End-to-end bit error performance evaluations verify the efficacy of the scheme and its success in overcoming synchronization errors

Distributed space time block coding and application in cooperative cognitive relay networks

The design and analysis of various distributed space time block coding schemes for cooperative relay networks is considered in this thesis. Rayleigh frequency flat and selective fading channels are assumed to model the links in the networks, and interference suppression techniques together with an orthogonal frequency division multiplexing (OFDM) type transmission approach are employed to mitigate synchronization errors at the destination node induced by the different delays through the relay nodes. Closed-loop space time block coding is first considered in the context of decode-and-forward (regenerative) networks. In particular, quasi orthogonal and extended orthogonal coding techniques are employed for transmission from four relay nodes and parallel interference cancellation detection is exploited to mitigate synchronization errors. Availability of a direct link between the source and destination nodes is studied. Outer coding is then added to gain further improvement in end-to-end performance and amplify-and-forward (non regenerative) type networks together with distributed space time coding are considered to reduce relay node complexity. A novel detection scheme is then proposed for decode-and-forward and amplify-and-forward networks with closed-loop extended orthogonal coding and closed-loop quasi-orthogonal coding which reduce the computational complexity of the parallel interference cancellation. The near-optimum detector is presented for relay nodes with single or dual antennas. End-to-end bit error rate simulations confirm the potential of the approach and its ability to mitigate synchronization errors

Técnicas de cooperação entre estações base para sistemas celulares

Mestrado em Engenharia Electrónica e TelecomunicaçõesA cooperação entre células é uma das áreas de pesquisa em maior crescimento, sendo uma solução promissora para sistemas celulares sem fio, por forma a amenizar a interferência entre as células, melhorar a equidade do sistema e aumentar a capacidade nos anos vindouros. Esta tecnologia já está em estudo no LTE-Advanced sob o conceito de coordenação multiponto (CoOMP). Esta dissertação insere-se na área de comunicações sem fios e tem como principal objectivo, estudar, implementar e avaliar o desempenho de esquemas de cooperação entre estações base, projectados para os futuros sistemas de comunicações móveis de portadora múltipla (OFDM/A). Especificamente, o sistema cooperativo estudado é constituído por duas estações base equipadas com um agregado de antenas, ligadas a uma unidade de processamento central, e dois terminais móveis equipados cada um com apenas uma antena. O sistema referido foi implementado de acordo com as especificações do LTE e avaliado em diversos cenários de propagação. As técnicas desenvolvidas permitem contornar os problemas relacionados com a má qualidade de canal entre emissor e receptor, melhorando o seu desempenho, especificamente ao nível da taxa de erros de transmissão.Multicell cooperation is one of the fastest growing areas of research, and it is a promising solution for cellular wireless systems to mitigate intercell interference, improve system fairness and increase capacity in the years to come. This technology is already under study in LTE-Advanced under the coordinated multipoint (CoOMP) concept. This dissertation is inserted in the wireless communications area, with its main objective being the study, implementation and evaluation of the performance of cooperative schemes between base stations designed for the future mobile communication multiple carrier systems (OFDM/A). Specifically, the cooperative system studied consists of two base stations, each with multiple antenna, connected to a central processing unit, and two mobile terminals, each equipped with only one antenna. The system referred to was implemented in accordance with the specifications of LTE and was tested in various different propagation situations. The developed techniques ensure the mitigation of problems related to interference between the portable terminals namely at the cell edges, improving specifically the bit error rate performance

Distributed space-time block coding in cooperative relay networks with application in cognitive radio

Spatial diversity is an effective technique to combat the effects of severe fading in wireless environments. Recently, cooperative communications has emerged as an attractive communications paradigm that can introduce a new form of spatial diversity which is known as cooperative diversity, that can enhance system reliability without sacrificing the scarce bandwidth resource or consuming more transmit power. It enables single-antenna terminals in a wireless relay network to share their antennas to form a virtual antenna array on the basis of their distributed locations. As such, the same diversity gains as in multi-input multi-output systems can be achieved without requiring multiple-antenna terminals. In this thesis, a new approach to cooperative communications via distributed extended orthogonal space-time block coding (D-EO-STBC) based on limited partial feedback is proposed for cooperative relay networks with three and four relay nodes and then generalized for an arbitrary number of relay nodes. This scheme can achieve full cooperative diversity and full transmission rate in addition to array gain, and it has certain properties that make it alluring for practical systems such as orthogonality, flexibility, low computational complexity and decoding delay, and high robustness to node failure. Versions of the closed-loop D-EO-STBC scheme based on cooperative orthogonal frequency division multiplexing type transmission are also proposed for both flat and frequency-selective fading channels which can overcome imperfect synchronization in the network. As such, this proposed technique can effectively cope with the effects of fading and timing errors. Moreover, to increase the end-to-end data rate, this scheme is extended for two-way relay networks through a three-time slot framework. On the other hand, to substantially reduce the feedback channel overhead, limited feedback approaches based on parameter quantization are proposed. In particular, an optimal one-bit partial feedback approach is proposed for the generalized D-O-STBC scheme to maximize the array gain. To further enhance the end-to-end bit error rate performance of the cooperative relay system, a relay selection scheme based on D-EO-STBC is then proposed. Finally, to highlight the utility of the proposed D-EO-STBC scheme, an application to cognitive radio is studied

Distributed convolutional-based coding for cooperative systems

Whenever size, power, or other constraints preclude the use of multiple-input multiple-output (MIMO) systems, wireless systems cannot benefit from the well-known advantages of space-time coding (STC) methods. Also the complexity (multiple radio-frequency (RF) front ends at both the transmitter and the receiver), channel estimation, and spatial correlation in centralized MIMO systems degrade the performance. In situations like these, the alternative would be to resort to cooperative communications via multiple relay nodes. When these nodes work cooperatively, they form a virtual MIMO system. The destination receives multiple versions of the same message from the source and one or more relays, and combines these to create diversity. There are two main cooperative diversity techniques for transmission between a pair of nodes through a multiple relay nodes: decode-and-forward (DF) and amplify-and-forward (AF) modes. In the DF mode, the signal received from the source node is demodulated and decoded before retransmission. In the AF mode, the relay node simply amplifies and retransmits the signal received from the source node. No demodulation or decoding of the received signal is performed in this case. In encoded cooperative communication networks, the diversity of the system degrades significantly. This diversity degradation is attributed to the errors made at the relay nodes. Consequently, if better reliability is achieved at the relay nodes, the diversity may improve. or even may be preserved. as compared to the error-free case. In light of this, the objective of this thesis is to devise coding schemes suitable for relay channels that aim at improving the end-to-end performance of such systems. In this thesis, we present a coding scheme suitable for cooperative networks where the source and relays share their antennas to create a virtual transmit array to transmit towards their destination. We focus on the problem of coding for the relay channels. While the relays may use several forwarding strategies, including AF and DF, we focus on coded DF relaying. We derive upper bounded expressions for the bit error rate (BER) assuming M -ary phase shift keying ( M -PSK) transmission and show that the proposed scheme achieves large coding gains and frill diversity relative to the coded non-cooperative case for a wide range of signal-to-noise ratio (SNR) of interest. To improve the detection reliability further, we consider antenna/relay selection on the performance of cooperative networks in conjunction with the distributed coding scheme proposed. For simplicity, we assume that there is one relay that is equipped with n R antennas and only the best antenna is selected. For this scenario, assuming DF and AF relaying, we derive upper bounds on the BER for M -PSK transmission. Our analytical results show that the proposed scheme achieves full diversity for the entire range of BER of interest, unlike the case without antenna selection. In the last part of the thesis, we consider the same system considered in the ideal case but now with system imperfections. In particular, we consider the case when the channel state information is estimated at all nodes involved in the transmission process. We derive upper bounds on the performance with imperfect channel estimation. Our results show that there is a performance degradation due to the presence of channel estimation error. However, the observations made in the case of ideal channel state information still hold for the non-ideal case

Cross-Layer design and analysis of cooperative wireless networks relying on efficient coding techniques

2011/2012This thesis work aims at analysing the performance of efficient cooperative techniques and of smart antenna aided solutions in the context of wireless networks. Particularly, original contributions include a performance analysis of distributed coding techniques for the physical layer of communication systems, the design of practical efficient coding schemes that approach the analytic limiting bound, the cross-layer design of cooperative medium access control systems that incorporate and benefit from advanced physical layer techniques, the study of the performance of such solutions under realistic network assumptions, and, finally the design of access protocols where nodes are equipped with smart antenna systems.XXV Ciclo198

Space-time coded cooperation in Wireless Networks

Nowadays, the concept of spatial diversity and cooperative networks attract a lot of interest because they improve the reliability of transmission in wireless networks. Spatial diversity is achieved when multiple antennas are at the transmitter. With great growth and demand for high speed high data rate wireless communication, more and more antennas are required. In order to achieve maximum diversity, these antennas should be well separated so that the fading on each link is uncorrelated. This condition makes it difficult to have more than two antennas on a mobile terminal. The relay's cooperation helps increase the diversity order without extra hardware cost. However, its main inconvenience is the use of multiple time slots compared to the direct link transmission. In this thesis, we develop a cooperation model which is composed of three terminals: source, relay and destination. The transmitters (source and relay) are composed of 2 antennas at the transmitter and the receivers (relay and destination) have 4 antennas. In the first proposed model, transmitters and decoders are composed of an Alamouti encoder and decoder respectively. In the second model, we also add a turbo encoder at transmitters and iterative decoding takes place at receivers. In both cases, the transmission cycle is composed of two time slots and the decode and forward (DF) protocol is applied. Multiple scenarios are considered by changing the environment of the transmission, such as line of sight (LOS) or non line of sight (NLOS) or by modifying the location of the relay between the source and destination. We also simulate an uplink and a downlink communication. All the scenarios show a coding gain with the turbo coded space-time cooperation