Resource allocation for multiuser cognitive radio with primary user´s cooperation

In this paper, we consider a downlink cognitive radio network (CRN) consisting of one cognitive base station (CBS) and multiple secondary users (SUs) that shares multiple channels with a primary network. The CRN is permitted to access the channel licensed to the primary user (PU) only if the signal to interference plus noise ratio (SINR) on that channel at the PU is higher than a predetermined level. The objective is to maximize the total throughput of the CRN with cooperation from the PU. For this, we propose a centralized efficient near-optimal joint channel and power allocation scheme based on dual optimization method. Specifically, the duality gap between the dual scheme and the optimal scheme is nearly zero as the number of channels gets large, while, in contrast to the exponential complexity of the optimal scheme, the complexity of the dual scheme is only linear in the number of channels. Additionally, a low-complexity sub-optimal two-step scheme is also proposed, the complexity of which is further reduced. Simulation results are obtained to verify the effectiveness of the proposed schemes. It is shown that the dual scheme achieves almost the same total throughput compared with that achieved by the optimal scheme even with small number of channels. Moreover, the performance of the two-step scheme is very close to that of the optimal scheme.