Performance Analysis of Relay Selection in the Presence of on–off Relay Traffic

The outage probability and bit error rate averaged over the distribution of the number of relays in Nakagami- m fading channels are analyzed for full and partial relay selection (RS) schemes. This analysis considers a random number of relays caused by the relay´s own on-off traffic. Based on this analysis, optimization of the relaying time is performed, and the optimal values of the relaying time are obtained. Numerical results show that there do exist locally optimal values of the relaying time for different system settings. For average outage probability, the optimal value increases when the threshold increases, the m parameters decrease, or partial selection is used instead of full selection. For an average bit error rate, the optimal value increases when the average signal-to-noise ratio (SNR) decreases, the m parameters decrease, the number of relays increases, or partial selection is used instead of full selection.