Joint Power Allocation and Best-Relay Positioning for Incremental Selection Amplify-and-Forward Relaying

Incremental selection amplify-and-forward relaying (ISAF) has the best performance of outage probability among relaying strategies and has been identified as the best protocol. This paper proposes to jointly optimize power allocation (PA) and best-relay position based on cooperative diversity for ISAF in order to minimize outage probability. The closed-form solution to the adaptive allocation algorithm based on high signal-to-noise ratio (SNR) approximation of outage probability is presented, assuming maximum ratio combining (MRC) at the destination. Simulation results have shown that the system performance of outage probability with the proposal outperforms the fixed PA algorithms, and much less power is needed to achieve the same outage probability at the same effective rate. The power saving can be as much as 9 dB compared to the equal power allocation scheme.