The Coverage-Latency-Capacity Dilemma for TDD Wide Area Operation and Related 5G Solutions

In this paper we present a novel configurable 5G time division duplex (TDD) frame structure, including a flexible scheduling (resource allocation) framework for wide area scenarios. The unavoidable tradeoffs between coverage, latency, and capacity are studied with the objective of deriving a 5G air interface solution that is capable of serving users with highly diverse service requirements. Among others, it is shown that coverage challenged users will experience larger latency, while other users can still be served with shorter latency if adopting the proposed 5G solution. Achieving low latency, does, however, come at cost of lower spectral efficiency, so our solution includes control mechanisms for determining on a per user basis if the link shall be optimized for latency or capacity.