Dynamic TDD: the Asynchronous Case and the Synchronous Case

Small cell networks (SCNs) are envisioned to embrace dynamic time division duplexing (TDD) in order to tailor downlink (DL)/uplink (UL) subframe resources to quick variations and burstiness of DL/UL traffic. The study of dynamic TDD is particularly important because it serves as the predecessor of the full duplex transmission technology, which has been identified as one of the candidate technologies for the 5th-generation (5G) networks. Up to now, the existing work on dynamic TDD only considered an asynchronous network scenario. However, the current 4G network is a synchronous one and it is very likely that the future 5G networks will follow the same system design philosophy for easy implementation. In this paper, for the first time, we consider dynamic TDD in synchronous networks and present analytical results on the probabilities of inter-cell inter-link interference and the DL/UL time resource utilization. Based on our analytical results, the area spectral efficiency is further investigated to shed new light on the performance and the deployment of dynamic TDD in future synchronous networks.