Impact of receive diversity on the performance of amplify-and-forward relaying under APS and IPS power constraints

In this letter, we investigate the impact of receive diversity on the error rate performance of a relay-assisted cooperative scheme in which the relay terminal is operating in amplify-and-forward (AF) mode under the so-called average power scaling (APS) and instantaneous power scaling (IPS) constraints. We assume that the source and relay terminals are each equipped with one antenna, while the destination terminal is equipped with N receive antennas. Through the derivation of symbol error rate expressions, we demonstrate that the maximum achievable diversity orders under APS and IPS constraints are N+1 and 2N, respectively.