Outage probability guaranteed relay selection in cooperative communications

This study is focused on the multiple relay selection problem in cooperative communications. The objective is to select the minimum set of relays to minimise the spectrum cost while preserving the signal-to-noise ratio (SNR) requirement at the destination. A probabilistic constraint is adopted to characterise the SNR outage requirement, which turns out to be intractable in general. As a solution, a tractable bound is derived for the outage probability constraint, with which the multiple relay selection problem can be formulated as a mixed integer optimisation problem with the on-and-off power mode at the relays, which is NP-hard. By utilising the intersections of the proposed bound for different relays, the authors propose an outage probability guaranteed relay selection algorithm which can find the optimal solution with significantly reduced complexity. A heuristic algorithm is also proposed for comparison. Extensive simulation results are provided to show the effectiveness of the proposed schemes.