Hybrid Overlay/Underlay Resource Allocation for Cognitive Radio Networks in User Mobility Environment

A novel resource allocation scheme for mobile secondary users (SU) in a cellular cognitive radio network (CRN) is presented, which shares spectrum with primary users (PU) by hybrid overlay/underlay sharing method. Assuming the PUs´ activities are stable during one period, this paper studies how to allocate subchannels to several mobile SUs and power control to avoid interference to PUs. The allocation problem is defined as a maximum throughput and fair access (MTFA) problem, which seeks fair access opportunities for each SU and maximizes the expected throughput as well. With the mobility information of SUs, we present a general framework to solve the problem, which is divided into several sub-problems during each basic time period (BTP). In the proposed framework, a maximum weighted bipartite matching (MWBM) is utilized to solve the MTFA problem in each BTP. Our proposal is evaluated by simulations using assumed mobility traces. Compared with channel greedy algorithm, the proposed algorithm outperforms in terms of access fair only with a small reduction in network throughput. Compared with random access algorithm, it has much better performance not only in throughput but also access fairness.