Resource Allocation in MIMO-OFDM-Based Cooperative Cognitive Radio Networks

We consider a MIMO-OFDM-based cooperative cognitive radio network (CCRN) in which there exists a number of regenerative relays to cooperate with the cognitive base station (CBS) in serving an SU. Our objective is to optimize the transmit covariance matrices at the CBS and the relays and obtain the optimal subcarrier pairing, relay assignment, where the dual-decomposition technique is recruited as a tool. The optimal resource allocation is performed subject to the individual power constraints in the CBS and relays and the interference power constraint on the primary system. Moreover, due to the high computational complexity of the optimal approach, a suboptimal algorithm is further proposed. The joint allocation of the resources in the proposed suboptimal algorithm is performed taking into account the decode-and-forward cooperation strategy, the interference imposed on the primary network, and the power budgets at the CBS and the relays. The performance of different approaches and the effect of deploying multiple antennas at users are explored through simulations.