Joint user pairing and resource allocation in full-duplex underlay cognitive radio networks

This paper considers a full-duplex underlay cognitive radio (CR) network with a full-duplex cognitive base station (CBS) transmitting signals to a set of half-duplex downlink secondary users (SUs) and receiving signals from a set of half-duplex uplink SUs. The problem of joint uplink and downlink SU pairing, channel and power allocation for maximizing the sum rate of the CR network is investigated. Two algorithms, one with high complexity and good performance, and the other one with low complexity and acceptable performance, are proposed to address the optimization problem. Simulation results are presented to verify the effectiveness of the proposed algorithms. It is shown that the proposed high-complexity algorithm always outperforms the proposed low-complexity algorithm and the optimal half-duplex schemes. It is also shown that the proposed low-complexity algorithm outperforms the optimal half-duplex schemes for loose transmit power constraints.