Precoding and Clustering Design for CoMP-CB in Downlink Heterogeneous Networks

Coordinated multi-point (CoMP) schemes represent an alternative solution to enhanced inter cell interference coordination (eICIC) to tackle 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. Then, we also study the effects of inter-cluster interference by comparing several static clustering solutions. 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 occupation saving.