Small Cell Dynamic TDD Transmissions in Heterogeneous Networks

Future wireless communication systems feature heterogeneous networks (HetNets), with small cells underlying existing macrocells. In order to maximize the off-loading benefits of small cells and mitigate the interference from the macrocell tier to the small cell tier, cell range expansion (CRE) and almost blank subframes (ABSs) have been designed for small cells and macrocells, respectively. Besides, enhanced 4th generation (4G) networks see interesting activities of dynamic time division duplexing (TDD) transmissions in small cells to adapt the communication service to the fast variation of downlink (DL) and uplink (UL) traffic demands. However, it is still unclear up to now, whether it is feasible to introduce the dynamic TDD technology into HetNets due to complexity issues. Therefore, in this paper, we investigate this fundamental problem and propose a feasible scheme to enable small cell dynamic TDD transmissions in HetNets. Simulation results show that compared with the static TDD scheme with CRE and ABS operations, the proposed scheme can achieve superior performance gains in terms of DL and UL packet throughputs when the traffic load is low to medium, at the expense of introducing the small cell DL to macrocell UL interference cancellation (IC) functionality in macrocell base stations (BSs).