Joint Coloring-Based Resource Allocation and Power Reduction in Dense Small Cell Networks

Deployment of small cells within macrocell layout is a promising approach to meet the rapid growth of traffic demand. Cell range expansion (CRE) has been introduced into LTE-Advanced to balance cell load. Small cell CRE users may suffer severe downlink (DL) co-tier and cross-tier interference introduced by dense deployment of small cells. In this paper, we propose a joint coloring-based resource allocation and power reduction scheme to mitigate interference to CRE users while maintaining the network throughput. In order to mitigate the co-tier interference, we firstly group CRE users based on interference graph by coloring and allocate orthogonal resources to different groups. Then, small base stations (SBSs) reduce power on resources occupied by CRE users in other SBSs. In order to alleviate the cross-tier interference, macro base stations (MBSs) power reduction is provided based on a utility function. We apply particle swarm optimization (PSO) strategy to obtain the optimal power. System level simulation results show that our proposed algorithm can greatly improve the CRE user throughput with slightly sacrificing the macrocell throughput. Meanwhile, it can improve the network energy efficiency (EE).