Date Added: Nov 2012
Coordinated Multi-Point (CoMP) techniques for LTE-Advanced systems promise high spectral efficiency and enhanced coverage; however, the performance of such systems heavily depends on the feedback quality. In this paper, the authors study the impact of quantized and delayed feedback on the achievable rate of CoMP systems. They first derive closed-form expressions and tight approximations on the sum-rate of Joint Transmission processing (JT) and Coordinated BeamForming (CBF) with imperfect Channel State Information (CSI). Schemes with increasing interference power at high SNR, i.e. CBF and JT to multiple users, are more sensitive to CSI imperfections than single-user JT.