Adaptive coordinated scheduling/beamforming scheme for downlink LTE-advanced system with non-ideal backhaul

Coordinated scheduling/beamforming (CS/CB) is regarded as a promising technique with non-ideal backhaul (NIB). However, due to the high latency of the NIB, the channel state information (CSI) and coordinated scheduling decisions will be severely delayed or even lost, resulting in serious system performance deterioration. To address this issue, an adaptive CS/CB scheme consisting of a semi-static coordinated resource allocation method as well as an adaptive scheduling scheme is presented in this paper. The semi-static resource allocation method is based on users' distribution information which varies relatively slowly with time, thus the method is inherently robust with the backhaul latency. Then according to the resource allocation decision, an adaptive scheduling scheme is designed to schedule users utilizing the latest CSI. Consequently, satisfactory system performance could be obtained under high backhaul latency. As shown in the simulation results, the proposed scheme always obtains significant gain in the cell edge user throughput over that of non-coordination schemes and traditional CS/CB schemes with different backhaul latency.