Power-efficient mobile backhaul design for CoMP support in future wireless access systems

Base Stations (BSs) cooperation techniques, also referred to as Coordinated Multi-Point (CoMP) in the 3GPP terminology, promise significant performance gains in future 4G and beyond systems. The counterpart to such gains is represented by the challenging requirements that CoMP puts on the backhaul network, which may prevent the inclusion of certain BSs selected for the cooperative cluster. The consequences of such a failure can be relevant for the overall power consumption. Those BSs which are not eligible for cooperation would be unnecessarily included in the channel estimation process, which consumes power both at the BS side (sending of reference pilots) and on the backhaul network side (exchange of Channel State Information (CSI) between BSs). To limit the detrimental effects of such CoMP cluster “unfeasibility”, we discuss the benefits of a cross-layer approach which relates wireless CoMP requests to the backhaul network status. We show how the preemptive exclusion of the non-eligible BSs results in a considerable saving of the overall power consumption. We further complement our system by proposing optical bypass techniques aimed at improving the CoMP support from the backhaul perspective. This results, on one side, in the enhancement of the overall CoMP feasibility performance, and, on the other side, in the reduction of the consumed power thanks to the offload of IP processing to the switching layer1.