In The Cognitive Radio Resource Allocation Algorithm Research

The resource allocation problem is discussed in the uplink transmission of an orthogonal frequency division multiple access (OFDMA) based CR net-work. The resource allocation aims to maximize the uplink throughput of SUs in CR network under the constraints of the primary user (PU) interference and the transmit power limits of SUs. In general, the optimal joint power and spec-trum allocation is known as NP-hard. To ease the computation complexity while maintain good performance, a novel particle swarm optimization (P-SO) based joint uplink power and spectrum allocation algorithm is proposed to solve this resource allocation problem. Due to the combinatorial nature of the resource allocation problem, our algorithm in which power continuously changes while the spectrum allocation strategy alters in the iteration process can obtain better performance than the existing decomposition based algorith-m that spectrum assignment and power allocation are implemented separately. For our specific application, we present new design of the position and velocity parameters as well as the iterative process involved in PSO. Simulation results show the effectiveness of the proposed algorithm.Furthermore, relay selection and resource allocation problem are consid-ered in a two-way cooperative relay CR network with several SUs. Different from other relay system, there is no fixed relay for SUs in the two-way relay CR network. Any SU in good channel condition can serve as a potential relay, which makes relay selection and resource allocation essential. In this disserta-tion, a novel joint relay selection and resource allocation scheme is proposed to maximize the throughput of the whole system. In order to reduce the com-putational complexity of the joint optimization problem, the scheme proposed in this dissertation is separated into two steps. In the first step, relay selection in conjunction with spectrum allocation is conducted based on the instanta- neous channel state information (CSI). In the second step, the optimal power allocation is carried out by convex optimization method and dual decomposi-tion method respectively for the direct link and relay link. Simulation results show that the proposed scheme improves the throughput of two-way relay CR network.Finally, the whole dissertation is summarized and future research direc-tions are pointed out.