Performance of threshold-based relay selection in amplify-and-forward cooperative networks over rayleigh fading channels

Relay selection can validly mitigate performance degradation caused by channel fading and increase diversity level, however all-time cooperation decreases bandwidth efficiency. This paper investigates performance of threshold-based relay selection in amplify-andforward cooperative networks over Rayleigh fading channels. SER closed-form expression and bandwidth efficiency formula are derived when M-PSK signal is given. This paper also provides numeric simulation to verify the analysis. It shows that, with low-SNR or few relay-nodes, raising threshold can improve bandwidth efficiency and, with high-SNR or lots of relay-nodes, decreasing threshold can dramatically improve SER performance.