Investigation of TDD frame structure design for latency reduction of LTE enhancement

Time division duplex (TDD) plays an important role in 5G systems because it employs an unpaired spectrum and offers channel reciprocity. However, employing TDD will lead to a long transmission latency due to the uplink/downlink transmission constraints. In this paper, we study the frame structure design for low latency communications in 5G TDD systems. We propose a frame structure design method that implements a shorter transmission time interval (TTI) and more switching points to allow lower latency in TDD systems. Analysis and evaluation results show that a shorter TTI and more switching points are not only beneficial in reducing user plane latency but also yield better performance in terms of user perceived throughput and user packet delay compared with current frame structure in LTE.