Clustering and precoding design for CoMP-CB in downlink heterogeneous networks

Coordinated multi-point (CoMP) schemes provide an alternative solution to enhanced inter cell interference coordination (eICIC) for the severe interference in downlink heterogeneous networks (HetNets). In particular, CoMP with coordinated beamforming (CB), which requires only channel state information sharing on the backhaul among the base stations (BSs), provides a good tradeoff between performance and complexity. In this work we consider CoMP-CB in downlink HetNets and we study two precoding schemes: with precoder 1 (P1) signal to leakage plus noise ratio (SLNR) beamforming is applied by all the BSs within the coordination cluster, whereas with precoder 2 (P2) only the macro BSs apply SLNR beamforming. By comparing three different static clustering solutions, we evaluate the proposed schemes in terms of both the achievable rate and the back-haul/feedback load. Numerical results show that the proposed CoMP-CB schemes outperform eICIC by providing a gain up to 25%. Moreover, P2 provides rates close to the ones achieved by P1, but with an important backhaul and feedback load saving.