A Two-Tier Clustering based Downlink Resource Allocation Algorithm for Small Cell Networks

This paper studies the downlink spectrum resource allocation problem in a small cell network and focuses on mitigating intra-tier interference between different small cells. A two-tier clustering based downlink resource allocation (TCRA) algorithm is proposed to perform spectrum resource allocation. To increase spectrum utilization, the algorithm allows different small-cell user equipments (SUEs) to share the same physical resource blocks (PRBs). Meanwhile, to mitigate intra-tier interference, those SUEs who are close to each other in distance are avoided to share the same PRBs as much as possible. To implement this, a two-tier clustering approach is introduced in PRB allocation. In the first tier, all small cells in the system are partitioned into a set of small cell clusters based on graph coloring, and those small cells with the same color are partitioned into the same cluster. In the second tier, all SUEs in each small cell cluster are further partitioned into a set of user clusters based on the interference graph of each small cell cluster. After the two-tier clustering, PRB allocation is performed based on the user clusters obtained. Simulation results show that the proposed TCRA algorithm can significantly improve the system performance in terms of total system capacity.