On Dynamic Time-Division-Duplex Transmissions for Small-Cell Networks

Motivated by the promising benefits of dynamic time division duplex (TDD), in this paper, we use a unified framework to investigate both the technical issues of applying dynamic TDD in homogeneous small-cell networks (HomSCNs) and the feasibility of introducing dynamic TDD into heterogeneous networks (HetNets). First, HomSCNs are analyzed, and a small-cell base-station (BS) scheduler that dynamically and independently schedules downlink (DL) and uplink (UL) subframes is presented, such that load balancing between the DL and UL traffic can be achieved. Moreover, the effectiveness of various interlink interference mitigation (ILIM) schemes and their combinations is systematically investigated and compared. Moreover, the interesting possibility of partial interference cancelation (IC) is also explored. Second, based on the proposed schemes, the joint operation of dynamic TDD together with cell range expansion (CRE) and almost blank subframe (ABS) in HetNets is studied. In this regard, scheduling polices in small cells and an algorithm to derive the appropriate macrocell traffic offload and ABS duty cycle under dynamic TDD operation are proposed. Moreover, the full IC and the partial IC schemes are investigated for dynamic TDD in HetNets. The user-equipment (UE) packet throughput performance of the proposed/discussed schemes is benchmarked using system-level simulations.