Resource allocation for constrained backhaul in picocell networks

Cellular network capacity and coverage can be improved by deployment of low power base stations referred to as picocells. Due to the associated deployment cost, a large number of picocells challenges the traditional approach to backhaul, where each cell has a dedicated backhaul link. This paper considers a more efficient approach, in which the backhaul is provided over a wireless channel shared among picocells. The considered backhaul network consists of multiple connector nodes (CNs) each providing backhaul to a group of picocells. A key problem in this setting is how to efficiently exploit and allocate this limited bandwidth resource among picocells. We consider joint scheduling and power allocation of backhaul transmissions based on limited bandwidth availability. We propose a backhaul scheduling approach based on traffic demands on picocells (i.e., the load of their mobile users), that maximizes the picocell utility. The approach applies to any underlying physical layer transmission scheme. We then investigate the proposed solution for an OFDM system. We first determine optimal power allocation under power and interference constraints for OFDM transmissions from multiple CNs. We then present an algorithm that performs joint scheduling and power allocation for OFDM transmissions in the backhaul channel.