Performance Evaluation of In-Band Full-Duplex System Using One-Time-Slot Two-Way Relay

Abstract

In-band full-duplex (IFD) two-way relay (TWR) system becomes one among the major concern for maximizing system capacity in wireless network, where one relay node and two source nodes using analog network coding (ANC) are deployed. This paper compares one-time-slot ANC (1TA) TWR, in which each node operates in IFD mode, with two-time-slot ANC (2TA) TWR, where each node is in in-band half-duplex mode. In addition, achievable sum rate of the 1TA-TWR is derived with adverse factors such as direct link interference as well as self-interference (SI), which is induced by IFD signaling. This paper proposes an iterative optimal power allocation (OPA) method to maximize the derived end-to-end sum rate, which is based on Lagrangian and Newton–Raphson algorithm under total power constraint. Numerical results elucidate the efficiency of the 1TA-TWR over the 2TA-TWR as the following: the 1TA-TWR based on the OPA becomes more and more viable than the 2TA-TWR based on existing OPA, as the relay node goes into the center of two source nodes, the link channel gain of mutual source nodes increases, and the SI channel gain approaches noise floor level.