Uplink-downlink interference alignment in TDD-based cellular networks

Considering the time duplex division (TDD)-based cellular network, this paper investigates the uplink/downlink interference under the framework of centralized-radio access network (C-RAN). According to different uplink/downlink configurations within three neighboring cells, two fundamental cases are discussed, which can be further classified into several scenarios. For the sake of tackling this kind of interference, the interference alignment (IA) transceivers are studied case-by-case. Specifically, by applying the concept of reference vectors, to which direction the interference is to be aligned, we propose a simply methodology to align the interference at the un-intended receivers. Then with respect to the antenna settings, the heuristic process of IA design is presented and discussed. Finally, simulations verify the proposed IA transceivers greatly outperform its benchmark, when there is strong uplink/downlink inter-cell interference.