Joint subcarrier and power allocation for DF-based multiuser two-way relay networks

Two-way decode-and-forward (DF) relay technique is an efficient method to improve system performance in 5G networks. However, traditional orthogonal frequency division multiplexing (OFDM) based two-way relay systems only consider a per-subcarrier relay strategy, which treats each subcarrier as a separate channel, which results in significant sum rate loss, especially in fading environments. In this paper, a joint coding scheme over multiple subcarriers is involved for multipair users in two-way relay systems to obtain multiuser diversity. A generalized subcarrier pairing strategy is proposed to permit each user- pair to occupy different subcarriers during the two transmission phases, i.e., the multiple access and broadcast phases. Moreover, a low complexity joint resource allocation scheme is proposed to improve the spectrum efficiency with an additional multi-user diversity gain. Some numerical simulations are finally provided to verify the efficacy of our proposal.