Robust design of SC-FDE based two-way relay systems under channel uncertainty

Abstract

In this paper, we consider the robust transceiver design for a single-carrier frequency-domain equalization (SC-FDE) based two-way amplify-and-forward (AF) relay system with imperfect channel state information (CSI). We formulate the optimization problem for the relay filter and destination equalizers as the maximization of the achievable bit rate (ABR) of the system subject to a relay transmit power constraint. Due to the lack of analytical tractable expression for the system ABR under imperfect CSI, solving the optimization problem directly is challenging. Thereby, a lower bound on the link ABR is first derived and adopted in the objective function. Based on the lower bound, the optimal equalizers at the two terminal nodes can be determined in closed form. Subsequently, the optimization of the relay filter is transformed into a convex power allocation problem and an efficient algorithm is proposed to find its global optimal solution. Numerical results are provided to confirm the ABR performance of the proposed robust two-way AF relaying strategy.