Performance Analysis of Decode-and-Forward with Cooperative Diversity and Alamouti Cooperative Space-Time Coding in Clustered Multihop Wireless Networks PDF Download

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Languages : en
Pages : 121

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Space-time coding and spatial diversity schemes enhance the performance of energy constrained multihop clustered relay networks. The purpose of this thesis is to evaluate the performance of techniques such as the decode-and-forward with cooperative diversity and the Alamouti space-time coding, which were primarily used in relay multiple-input multiple-output communications, in distributed clustered two-hop and multihop relaying networks consisting of single-antenna terminals. Simulation results, in single carrier Rayleigh and Stanford University Interim channels for phase shift keyed and quadrature amplitude modulation, show that the use of the decode-and-forward with cooperative diversity and the Alamouti cooperative space-time coding schemes improve the error probability performance in a power constrained, clustered multihop relaying network operating in a multipath fading environment.

Author: Gbenga Adetokunbo Owojaiye
Publisher:
ISBN:
Category :
Languages : en
Pages :

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In this thesis, space-time block codes originally developed for multiple antenna systems are extended to cooperative multi-hop networks. The designs are applicable to any wireless network setting especially cellular, adhoc and sensor networks where space limitations preclude the use of multiple antennas. The thesis first investigates the design of distributed orthogonal and quasi-orthogonal space time block codes in cooperative networks with single and multiple antennas at the destination. Numerical and simulation results show that by employing multiple receive antennas the diversity performance of the network is further improved at the expense of slight modification of the detection scheme. The thesis then focuses on designing distributed space time block codes for cooperative networks in which the source node participates in cooperation. Based on this, a source-assisting strategy is proposed for distributed orthogonal and quasi-orthogonal space time block codes. Numerical and simulation results show that the source-assisting strategy exhibits improved diversity performance compared to the conventional distributed orthogonal and quasi-orthogonal designs. Motivated by the problem of channel state information acquisition in practical wireless network environments, the design of differential distributed space time block codes is investigated. Specifically, a co-efficient vector-based differential encoding and decoding scheme is proposed for cooperative networks. The thesis then explores the concatenation of differential strategies with several distributed space time block coding schemes namely; the Alamouti code, square-real orthogonal codes, complex-orthogonal codes, and quasiorthogonal codes, using cooperative networks with different number of relay nodes. In order to cater for high data rate transmission in non-coherent cooperative networks, differential distributed quasi-orthogonal space-time block codes which are capable of achieving full code-rate and full diversity are proposed. Simulation results demonstrate that the differential distributed quasi-orthogonal space-time block codes outperform existing distributed space time block coding schemes in terms of code rate and bit-error-rate performance. A multidifferential distributed quasi-orthogonal space-time block coding scheme is also proposed to exploit the additional diversity path provided by the source-destination link. A major challenge is how to construct full rate codes for non-coherent cooperative broadband networks with more than two relay nodes while exploiting the achievable spatial and frequency diversity. In this thesis, full rate quasi-orthogonal codes are designed for noncoherent cooperative broadband networks where channel state information is unavailable. From this, a generalized differential distributed quasi-orthogonal space-frequency coding scheme is proposed for cooperative broadband networks. The proposed scheme is able to achieve full rate and full spatial and frequency diversity in cooperative networks with any number of relays. Through pairwise error probability analysis we show that the diversity gain of the proposed scheme can be improved by appropriate code construction and sub-carrier allocation. Based on this, sufficient conditions are derived for the proposed code structure at the source node and relay nodes to achieve full spatial and frequency diversity. In order to exploit the additional diversity paths provided by the source-destination link, a novel multidifferential distributed quasi-orthogonal space-frequency coding scheme is proposed. The overall objective of the new scheme is to improve the quality of the detected signal at the destination with negligible increase in the computational complexity of the detector. Finally, a differential distributed quasi-orthogonal space-time-frequency coding scheme is proposed to cater for high data rate transmission and improve the performance of noncoherent cooperative broadband networks operating in highly mobile environments. The approach is to integrate the concept of distributed space-time-frequency coding with differential modulation, and employ rotated constellation quasi-orthogonal codes. From this, we design a scheme which is able to address the problem of performance degradation in highly selective fading environments while guaranteeing non-coherent signal recovery and full code rate in cooperative broadband networks. The coding scheme employed in this thesis relaxes the assumption of constant channel variation in the temporal and frequency dimensions over long symbol periods, thus performance degradation is reduced in frequencyselective and time-selective fading environments. Simulation results illustrate the performance of the proposed differential distributed quasi-orthogonal space-time-frequency coding scheme under different channel conditions.

Author: Yindi Jing
Publisher: Springer Science & Business Media
ISBN: 1461468310
Category : Technology & Engineering
Languages : en
Pages : 118

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Distributed Space-Time Coding (DSTC) is a cooperative relaying scheme that enables high reliability in wireless networks. This brief presents the basic concept of DSTC, its achievable performance, generalizations, code design, and differential use. Recent results on training design and channel estimation for DSTC and the performance of training-based DSTC are also discussed.

Author: B. Tulasi Sowjanya
Publisher: Archers & Elevators Publishing House
ISBN: 8119385128
Category : Antiques & Collectibles
Languages : en
Pages : 65

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Author: Panupat Poocharoen
Publisher:
ISBN:
Category :
Languages : en
Pages : 140

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The imperfections of the propagation channel due to channel fading and the self-generated noise from the RF front-end of the receiver cause errors in the received signal in electronic communication systems. When network coding is applied, more errors occur because of error propagation due to the inexact decoding process. In this dissertation we present a system called Partial Network Coding with Cooperation (PNC-COOP) for wireless ad hoc networks. It is a system which combines opportunistic network coding with decode-and-forward cooperative diversity, in order to reduce this error propagation by trading off some transmission degrees of freedom. PNC-COOP is a decentralized, energy efficient strategy which provides a substantial benefit over opportunistic network coding when transmission power is a concern. The proposed scheme is compared with both opportunistic network coding and conventional multi-hop transmission analytically and through simulation. Using a 3-hop communication scenario, in a 16-node wireless ad hoc network, it is shown that PNC-COOP improves the BER performance by 5 dB compared to opportunistic network coding. On average, it reduces the energy used by each sender node around 10% and reduces the overall transmitted energy of the network by 3.5%. When retransmission is applied, it is shown analytically that PNC-COOP performs well at relatively low to medium SNR while the throughput is comparable to that of opportunistic network coding. The effectiveness of both opportunistic network coding and PNC-COOP depends not only on the amount of network coding but also on other factors that are analyzed and discussed in this dissertation.

Author: Michael B. Matthews
Publisher: Institute of Electrical & Electronics Engineers(IEEE)
ISBN: 9780780386228
Category : Technology & Engineering
Languages : en
Pages : 1142

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Author: Hamid Jafarkhani
Publisher: Cambridge University Press
ISBN: 1139444441
Category : Technology & Engineering
Languages : en
Pages : 320

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This book covers the fundamental principles of space-time coding for wireless communications over multiple-input multiple-output (MIMO) channels, and sets out practical coding methods for achieving the performance improvements predicted by the theory. Starting with background material on wireless communications and the capacity of MIMO channels, the book then reviews design criteria for space-time codes. A detailed treatment of the theory behind space-time block codes then leads on to an in-depth discussion of space-time trellis codes. The book continues with discussion of differential space-time modulation, BLAST and some other space-time processing methods and the final chapter addresses additional topics in space-time coding. The theory and practice sections can be used independently of each other. Written by one of the inventors of space-time block coding, this book is ideal for a graduate student familiar with the basics of digital communications, and for engineers implementing the theory in real systems.

Author: Zheng Li
Publisher:
ISBN: 9781124782478
Category : Asynchronous transfer mode
Languages : en
Pages :

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Space-time coding (STC) is a promising technique to achieve transmit diversity in Multiple-Input-Multiple-Output (MIMO) systems. Recently, space-time coding in a distributed fashion (DSTC) for cooperative relay networks attracts a lot of research interests. The design of space-time coding for cooperative relay networks has some new challenges which are different from the design of space-time coding for MIMO systems. The synchronization issue is one of the most important problems in the design of distributed space-time coding for cooperative communication systems since the cooperative systems are asynchronous in nature, e.g., there may exist timing errors and multiple frequency offsets in the cooperative systems. In this dissertation, we will discuss and study several designs of space-time coding for cooperative systems with different system models and in different asynchronous scenarios. In the first topic, we attempt to design very simple space-time coding schemes for cooperative systems with timing errors in Amplify-and-Forward (AF) mode. One of the major purposes is to make the relay nodes as simple as possible so that the relay nodes only need to implement very simple operations with a very low complexity. Another major purpose is to achieve full diversity and fast Maximum-Likelihood (ML) decoding at the receiver despite the existence of the timing errors. Except for the timing errors, the problem of multiple frequency offsets is another kind of asynchronous error which should be solved as well. In the second topic, we investigate the scenario that the timing errors and the multiple frequency offsets are existed simultaneously in the Decode-and-Forward (DF) cooperative systems. We adopt OFDM to combat the timing errors and propose an intercarrier interference (ICI) Self-Cancellation scheme to suppress the ICI caused by multiple frequency offsets. In the third topic, we consider the physical layer security issue in cooperative systems with timing errors. In order to avoid illegal interception of the eavesdropper in a cooperative system, we propose a distributed differential encoding/decoding scheme combined with deliberate signal randomization to achieve Low Probability of Interception (LPI) as well as to obtain full diversity regardless of the timing errors.

Author: Mohamed M. M. Elfituri
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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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.

Author: Michael A. Tope
Publisher:
ISBN: 9781423506126
Category :
Languages : en
Pages : 94

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Currently wireless multi-hop ad hoc networks utilize protocols that relay packets of data node-by-node along a path connecting the source node to the sink node. This thesis describes a new methodology called "Cooperative Diversity" where information is relayed from the source to the sink via clusters of neighboring nodes. We first describe a routing protocol to establish spatially diversified paths through a field of randomly dispersed nodes. Second, an idealized configuration called the "Synthetic Waveguide" is introduced and its information theoretic channel capacity is developed. Third, we derive an outage model based channel capacity for the synthetic waveguide operating with a low forwarding latency. The low latency channel capacity is far different from that predicted by traditional channel capacity. Next, a simple modulation called stuttered simulcast is introduced and shown to approach the performance of an optimal distributed space-time code. Finally, a Monte Carlo simulation of the cooperative diversity routing protocol confines its superior performance in regions of operational interest.