Random-based fair allocation in Multi-Relay cooperative OFDM system

In this paper, a novel Multi-relay Adaptive Random Selection (MARS) strategy in a dual-hop multi-relay OFDM system is proposed. In this strategy, the relays cooperate according to contribution factors suggested by each relay. The selection of the OFDM sub-channels is based on uniform random distribution where the thresholds of the uniform random variable are associated with the contribution factors. This approach guarantees fairness in allocating the resources in each relay. The approach is compared with static allocation of the OFDM sub-channels. The MARS strategy is tested in a multi relay system over flat and selective Rayleigh fading channels. Simulation results show the superiority of the proposed scheme in improving the OFDM system performance in terms of BER. The performance is achieved by creating a virtual diversity by randomizing the allocation where no channel information is required.