Downlink-to-Uplink Interference Cancellation in Cloud Radio Access Networks

Dynamically choosing the time-division duplex (TDD) configuration in Long-Term Evolution (LTE) results in intercell interference. Among various interference types, the downlink-to-uplink interference is the strongest due to the much larger downlink (DL) transmission power from a base station than the uplink (UL) transmission power from a user equipment (UE). Although coordinating the neighboring base stations to operate in the same UL/DL configuration is a way to mitigate the interference, the flexibility of TDD is sacrificed. In this paper, we discuss an interference cancellation method exploiting the cloud radio access network (C-RAN) architecture. The downlink- to-uplink interference is cancelled by utilizing the knowledge of the downlink signal available at the cloud server. Simulation results show the effectiveness of this method, which maintains the flexibility of dynamically choosing the UL/DL configuration according to the traffic demand in the TDD system.