Performance Evaluation of CS/CB for Coordinated Multipoint Transmission in LTE-A Downlink

Coordinated multipoint (CoMP) processing is a key enabling technique in Long Term Evolution-Advanced (LTE-A) to improve the system spectral efficiency. Among the CoMP processing schemes, while joint transmission (JT) from multiple coordinated eNBs has high computing complexity due to the data sharing, coordinated scheduling/coordinated beamforming (CS/CB) lowers the backhaul requirement. In this paper, based on the modified signal-to-leakage-and-noise ratio (M-SLNR), a transmit precoding algorithm is proposed for CS/CB. The performance of this algorithm is evaluated through system level simulations under imperfect CSI scenario. As illustrated by the simulation results, the proposed algorithm is capable of significantly improving the spectral efficiency of CS/CB than that of single cell multiuser multiple-input-multiple-output (MU-MIMO), upon suppressing the dominant leakage interference using as few spatial resources as possible. Specifically, intra-site CoMP and inter-site CoMP employing the proposed algorithm have a spectral efficiency gain of 13% and 20%, respectively, compared with single cell MU-MIMO.