In this paper, a decode‐and‐forward (DF) cooperative network under Nakagami‐m fading is considered. A threshold‐based selection relaying scheme is used to choose the relays for cooperation and the selected relays then employ distributed space‐time coding (DSTC) to retransmit their detected symbols to destination. When employing DSTC, due to decoding errors at DF relays, intersymbol interference (ISI) would be inevitable in these networks. A new beamforming (BF) method, named as bisector alignment, is proposed for mitigating ISI between symbols of DSTC scheme caused by erroneous detection of symbols at relay. It is demonstrated that this scheme by using a simple maximal ratio combining is more power efficient compared with other existing methods. A closed‐form expression for end‐to‐end bit error rate (BER) of the system is derived and the asymptotic behavior analysis of the system illustrates …
