Optimal Resource Allocation for Two-Way Relay-Assisted OFDMA

This paper studies the optimal resource allocation problem for the relay-assisted orthogonal frequency-division multiple-access (OFDMA) -based multiuser system. A new transmission protocol, named hierarchical OFDMA, is proposed to support two-way transmissions between the base station (BS) and each mobile user (MU) with or without an assisting relay station (RS) in "relay" or "direct" mode, respectively. In particular, two-way relaying is applied to MUs in relay mode with two relay-operations: decode-and-forward (DF) and amplify- and-forward (AF). Applying convex optimization techniques, efficient algorithms are developed for optimizing the resource allocation at the BS, RSs, and MUs. Simulation results show that substantial throughput gains are achievable by the proposed two- way relaying and optimal resource allocation schemes over the conventional one-way relaying and fixed resource allocation for relay-assisted OFDMA-based wireless networks.