Switch-and-examine node selection for efficient relaying systems

The opportunistic relaying in [1] was proposed as an efficient cooperative protocol in the wireless multi-hop systems. However, the opportunistic relaying may still have high complexity as the number of relay nodes increases since the link quality of the paths generated by multiple relay nodes should be monitored. In this paper, we propose a novel multi-hop relay protocol named ?switch and examine node selection? (SENS), where the relay node is selected if its link quality is above a certain threshold which is set to satisfy the required performance and the selected link is maintained unless its link quality does not fall below the threshold. From our derived statistics of the received output signal-to-noise ratio (SNR), we obtain the optimal threshold in terms of the link performance such as the average output SNR, the outage probability, and average error rate. Using the optimal threshold, we show from the analytical and numerical results that the performance of our proposed SENS protocol provides the same performance as the opportunistic relaying protocol while the complexity of our proposed scheme is much lower than the one of opportunistic system.