Energy-efficient resource allocation for multi-user two-way relay-assisted OFDM system

Energy-efficient communication has attracted more and more attention due to the large energy consumption in wireless communication network. Relay-assisted OFDM cellular network is one of the most effective frameworks in the IMT-Advanced system to improve the spectral efficiency. This paper investigates the energy-efficient resource allocation for multiuser two-way multi-relay OFDM network. We formulate a joint optimization problem of subcarrier pairing based on energy-efficient subcarrier assignment, relay selection, rate allocation to minimize the total transmit power under individual uplink and downlink QoS requirement for each user. In order to solve the optimization problem with low computational complexity, the problem is divided into three subproblems. Then, the optimal subcarrier assignment algorithm is proposed as well as the Lagrange dual method is applied to solve the optimal rate allocation. Furthermore, the simulation results illustrate our analysis and the performance of the proposed schemes.