Adaptive modulated cooperative system with selection combining

In this paper, adaptive modulation is implemented for a selection combining Demodulate and Forward Relay system. In this method, the source and relay select the modulation type based on the channel quality measurement, which is the output SNR, to improve the total throughput of the system. The adaptation thresholds are computed by solving an optimization problem. The model is generalized for the N-relay system and the optimization problem is modified for this case. Adaptive modulation is then employed for the N-relay DMF system. The results demonstrate that employing the proposed method improves the total throughput of the system by keeping the BER performance at the target level.