On the performance gain of flexible UL/DL TDD with centralized and decentralized resource allocation in dense 5G deployments

Ultra dense small cell deployments and a very large number of applications are expected to be the essential aspects of the newly emerging 5
^th
generation (5G) wireless communication system. To match the diverse quality of service requirements imposed by a variety of applications, dynamic TDD is proposed as a solution by enabling flexible utilization of the spectrum for uplink and downlink of each cell. In this paper, the system performance of flexible (dynamic) TDD is compared to a fixed portioning of resources for uplink and downlink. Further, the degree of centralization for resource management is investigated in the context of dynamic TDD, because multi-cell scheduling will be important for the design of 5G ultra-dense network architecture. The results show that dynamic TDD is indeed a very promising option for 5G networks, and substantially decreases packet outage delays. We find that the performance gap between centralized and decentralized scheduling is small in case of planned deployments. However, centralized scheduling may be beneficial in certain dynamic TDD deployment scenarios with a very asymmetric access point distribution.