Capacity and Outage Probability in Multiuser OFDM Dual-Hop Relay Systems

The conventional amplify-and-forward relaying protocol has less complex but worse performance than the decode-and-forward type. In the orthogonal frequency division multiplexing (OFDM) multihop relay systems, the system capacity can be enhanced via using the subcarrier permutation scheme at the relay terminals. However, under the multiuser scenario, one subcarrier may possess the best condition for several users, but only one user can choose it to transmit the data. This competitive relation among users will influence the system performance. In this paper, the system capacity and outage probability with a direct link are studied for the multiuser OFDM dual-hop relay system in Rayleigh fading channels. Simulation and numerical results show that the system performance has a large impact under a multiuser scenario.