Comp Transmission in Cloud Radio Access Networks

Coordinated multi-point (CoMP) is an efficient technique to increase cell-edge coverage probability and throughput in cloud radio access network (C- RAN). In this paper, we develop a tractable framework to analytically evaluate the performance of two typical CoMP schemes, namely, zero-forcing beamforming(ZFBF) and non-coherent joint transmission (NC-JT). Using the stochastic geometry based approach, we characterize the signal-to- interference ratio (SIR) distribution at a typical downlink user. Furthermore, we consider the effect of imperfect channel state information (CSI) on coverage probability of the typical user from the practical design perspective. It is observed that ZFBF can outperform NC-JT only when there is sufficient overhead to convey the quantized CSI. In summary, this work serves as a good rule of thumb to compare the effect of CoMP techniques in C-RAN.