Downlink overhead reduction for multi-cell cooperative processing enabled wireless networks

Multi-cell Cooperative Processing (MCP) has been recognised as an efficient technique for increasing spectral efficiency of future cellular systems. However the provided benefits come at the cost of increased overhead and computational complexity; Mobile Stations (MSs) need to feed back to their assigned Base Station (BS) their local channel state information (CSI) which in turn needs to be transmitted to the Control Unit that coordinates the cooperating BSs. Furthermore user data needs to be routed to and from all cooperating BSs on the downlink and uplink respectively. Therefore in order for the overhead to be affordable, it is admitted that cooperating BSs shall be organised in clusters of a limited size. Nevertheless, it is still crucial that CSI feedback and inter-base information exchange be reduced. In this paper linear precoding is considered with the target of overhead minimisation of the downlink. A novel technique is proposed which allows MSs not to feed back the channel coefficients related to the cluster BSs that provide weak channel quality. This is shown to provide a good trade-off between performance and overhead.