Analysis and optimization of backhaul sharing in CoMP

The great potential of multi-cell processing in Coordinated Multi-point (CoMP) transmission is hindered by the limited bandwidth of the backhaul network. In this paper, we tackle this problem from two perspectives. First, we provide a thorough analytical study of the expected capacity when employing zero forcing (ZF) beamforming based on quantized channel state information (CSI). We derive simple yet accurate expression for the average capacity per user when Zero-forcing precoders are employed. Then, we propose a low-complexity algorithm to share the backhaul bandwidth between the different users in a fair manner. The algorithm does water-filling for the backhaul bandwidth among users based on their signal-to-interference ratio (SIR), with a target of Equal SIR for all users. We analytically prove that the proposed algorithm is more fair than the standard techniques for backhaul sharing. Simulation results are provided to asses the analytical findings about the superiority of our algorithm in terms of both fairness and sum rate.