Joint design of multi-tap filters and power control for FBMC/OQAM based two-way decode-and-forward relaying systems in highly frequency selective channels

In this paper we study the achievable rate region of an FBMC based two-way decode-and-forward relaying system. Unlike a CPOFDM system, the FBMC based systems experience inter-carrier interference and inter-symbol interference especially in a highly frequency selective channel. To calculate the resulting rate region, we have to solve a joint optimization of the per-subcarrier multitap filters at the relay as well as at the users, which is nonconvex. Therefore, we resort to a two-step approach. First, we design closed-form solutions for the per-subcarrier pre-equalizers and equalizers at all nodes. Then we derive an optimal power allocation scheme to maximize the achievable rate. Simulation results show that the achievable sum rate increases as the number of taps used for pre-equalization and equalization at the subcarriers increases.