Performance comparison of cooperative relay links with different relay processing strategies: Nakagami/Gamma approximation approaches

EURASIP Journal on Wireless Communications and Networking, Apr 2014

In this article, we investigate and compare the error performance of two-hop communication links (THCLs) with multiple relays, when distributed and cooperative relay processing schemes are respectively employed. Our main objectives include finding some general and relatively simple ways for estimating error performance and demonstrating the trade-off of using cooperative relay processing. One distributed relay processing and two cooperative relay processing schemes are compared. In the two cooperative relay processing schemes, one assumes the ideal relay cooperation, in which relays exchange information without consuming energy, while the other one assumes energy consumption for relay cooperation. In this paper, the error performance of the THCLs employing the considered relay processing schemes is investigated, when the channels from source to relays, the channels for information exchange and that from relays to destination experience various types of fading modeled by the Nakagami-m distributions. In order to derive the formulas for the bit error rate (BER) of the THCLs employing binary phase-shift keying (BPSK) modulation and various relay processing schemes, we introduce the Nakagami and Gamma approximation for finding the distribution functions of various variables encountered. Our studies show that the proposed approximation approaches are highly effective, which are capable of accurately predicting the BER of the THCLs supported by the different relay processing schemes.

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Performance comparison of cooperative relay links with different relay processing strategies: Nakagami/Gamma approximation approaches

Jia Shi Chen Dong Lie-Liang Yang 0 School of Electronics and Computer Science, University of Southampton , Southampton, SO17 1BJ, UK In this article, we investigate and compare the error performance of two-hop communication links (THCLs) with multiple relays, when distributed and cooperative relay processing schemes are respectively employed. Our main objectives include finding some general and relatively simple ways for estimating error performance and demonstrating the trade-off of using cooperative relay processing. One distributed relay processing and two cooperative relay processing schemes are compared. In the two cooperative relay processing schemes, one assumes the ideal relay cooperation, in which relays exchange information without consuming energy, while the other one assumes energy consumption for relay cooperation. In this paper, the error performance of the THCLs employing the considered relay processing schemes is investigated, when the channels from source to relays, the channels for information exchange and that from relays to destination experience various types of fading modeled by the Nakagami-m distributions. In order to derive the formulas for the bit error rate (BER) of the THCLs employing binary phase-shift keying (BPSK) modulation and various relay processing schemes, we introduce the Nakagami and Gamma approximation for finding the distribution functions of various variables encountered. Our studies show that the proposed approximation approaches are highly effective, which are capable of accurately predicting the BER of the THCLs supported by the different relay processing schemes. 1 Introduction It has been widely recognized that cooperative communications will play important roles in the future generations of wireless communication systems [1-4]. One type of cooperative communication systems is the relayassisted, where distributed mobile nodes, often referred to as relays, are employed for attaining cooperative diversity, in order to enhance the reliability of wireless communications [5,6]. The relay-assisted wireless communication systems have been investigated in the context of various relay protocols, which include amplify-and-forward (AF), decode-and-forward (DF), compress-and-forward (CF) protocols, etc. [5-7]. Along with the relay-assisted wireless communications, a lot of researches have addressed the bit error rate (BER) or symbol error rate (SER) analysis, when assuming communications over, such as, Rayleigh fading, Rician fading and Nakagami-m fading channels [8-15]. In the analyses, various cooperative relay scenarios have been considered, which include the classic three-node relay network [13,14], serial or parallel multihop cooperative relay networks [9,12,15], etc. A lot of exact or approximate closed-form formulas have been derived for evaluating the BER/SER of considered scenarios. In [10], the exact average SER formulas have been obtained for the cooperative network, where a source sends messages to a destination with the aid of multiple AF relays, when assuming communications over flat Rayleigh fading channels. In [11], the SER analysis has been done in the context of the multihop cooperative relay networks over various types of fading channels, when both the number of relays and the number of hops may take arbitrary values. In addition to BER/SER, the outage probability of cooperative wireless systems has been investigated, for example, in [16-19]. In more detail, the lower and asymptotic bounds of outage probability have been derived in [16] for dual-hop relay networks experiencing Rayleigh fading. By contrast, in [17,19], the outage probability has been derived, when assuming communication over independent and non-identically distributed Nakagami-m fading channels. Furthermore, considering capacity/throughput, in [20-22], the authors have studied the capacity bound and rate region of two-hop relay networks. In [21], a traditional three-node relay system has been considered, and the upper and lower bounds of ergodic capacity have been derived, when various relay schemes are employed. In [22], the capacity bounds have been analyzed in the context of multinode ad hoc networks. In the published references, such as [13,18,23,24], on the relay communications employing cooperative relays, a typical assumption used is ideal cooperation among relays. Under this assumption, there is no energy consumption for the information exchange required by cooperation and, furthermore, other overheads required are also often ignored. Against this background, in [25], we studied and compared various relay processing schemes in association with the two-hop communication links (THCLs), where multiple relays assisted one source to communicate with a destination. We demonstrated that the studies under ideal assumptions often result in misleading observations, when practical scenarios were considered. Continuing the work in [25], in this paper, we investigate further three types (...truncated)


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Jia Shi, Chen Dong, Lie-Liang Yang. Performance comparison of cooperative relay links with different relay processing strategies: Nakagami/Gamma approximation approaches, EURASIP Journal on Wireless Communications and Networking, 2014, pp. 53, Volume 2014, Issue 1, DOI: 10.1186/1687-1499-2014-53