Performance Analysis of Fixed-Gain Amplify-and-Forward Relaying With MRC

Relay transmission has recently attracted much attention since it can offer spatial diversity with single antenna terminals. This paper addresses the performance of a multiple-relay system with fixed-gain amplify-and-forward (AF) relaying in Nakagami-m fading. A tight upper bound on the average symbol error probability (SEP) is obtained for a system with K relays and when the maximal ratio combining (MRC) is used at the destination. Based on the obtained bound, a maximum diversity order of m(K + 1), where m is the fading parameter, is shown. Moreover, the problem of power allocation (PA) to minimize the SEP upper bound is investigated. Numerical results illustrate significant gains provided by the proposed PA over equal PA (EPA) under various channel conditions.