Cooperative dynamic spectrum access for small cell networks with interference mitigation and QoS guarantee

Deployment of small cells (SCs) can provide high network capacity and extend the coverage for macrocells. However, when more small base stations are deployed or the traffic loads of macro users become heavier, interference becomes the major obstacle impacting the potential gain of SCs. In this paper, a cooperative dynamic spectrum access (CDSA) scheme under orthogonal channel deployment with centralized control manner is proposed. The CDSA allows SCs to sense the resource blocks (RBs) periodically. The optimal sensing period is determined using efficacy coefficient method to minimize the cross-tier interference and provide QoS guarantee at the same time. The effective capacity (EC) and interference ratio function of sensing period are also derived for the above solution in CDSA. To alleviate intra-tier interference and improve spectrum efficiency, CDSA achieves the optimal RBs allocation and power control by applying the particle swam optimization (PSO) method. Simulation results demonstrate that the CDSA performs much better on interference mitigation and QoS guarantee than the fixed and the randomized schemes under co-channel deployment. Especially in when the SCs are very dense or the traffic load of the macrocell is very heavy, the improvement of CDSA is obviouser.