An Interference Management Strategy for Dynamic TDD in Ultra-dense Networks.

Ultra-dense networks (UDNs) are considered to meet demands for fast increasing throughput requirements per unit area in hotspots. Along with the dynamic variation of the throughput for the uplink/downlink (UL/DL), flexible resource allocation schemes become very important in UDNs based on time division duplex (TDD) for densely deployed access points (APs) and user equipments (UEs). In this paper, we propose a strategy to resolve the interference problem brought by dynamic TDD in UDNs. Firstly, we design a clustering method based on the Chameleon algorithm to reduce the inter-cluster interference. With the clustering results, the throughput requirements of each cluster become similar. Then we adopt a dynamic UL/DL resource allocation (DRA) for small cells in each cluster, with fewer adopted frame structures reaching more users’ throughput requirements adequately. At last, in each cluster, we adopt multi-cell beamforming (MBF) in small cells with the same frame structure to further mitigate inter-cell interference (ICI). Simulation results show that our proposed strategy could achieve satisfactory performance in UL/DL throughput.