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

Jia Shi,Chen Dong,Lie-Liang Yang

doi:10.1186/1687-1499-2014-53

Abstract

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.

Highlights

It has been widely recognized that cooperative communications will play important roles in the future generations of wireless communication systems [1,2,3,4]
The results show that the error performance predicted from the formulas derived based on the approximation approaches agree well with that obtained by simulations for the various scenarios addressed
Our performance studies show that both the approximation approaches can be confidently used for predicting the bit error rate (BER) of the schemes generating equalgain combining (EGC)-type decision variables, the Nakagami-SAp may yield more accurate results than the Nakagami-TAp

Summary

Introduction

It has been widely recognized that cooperative communications will play important roles in the future generations of wireless communication systems [1,2,3,4]. We assume that the relays do not communicate with each other, instead, they receive signals from the source, share their information with the aid of the IECU and independently process and transmit their signals to the destination. Since information exchange is ideal, the signals received by the IECU are given by ycu = yr, where yr is given by (1) In this case, assuming that the CSI of all S-R channels are known to the IECU, it can form the decision variable based on MRC as zcu = hHsrycu =. L S-R channels experience independent Nakagami-m fading with the same PDF determined by the parameters msr and sr, the average BER of the IECU’s detection can be expressed as [28,29,30].

Bit error rate of CRP

Conclusions