Rate Loss Caused by Limited Feedback and Channel Delay in Coordinated Multi-Point System

Abstract

This paper investigates the performance of clustered base station (BS) coordination with limited feedback and channel state information (CSI) delay. Given imperfect CSI caused by the limited feedback and channel delay, the expression of data rate per cell is derived. Moreover, compared to the rate with perfect CSI, a rate loss upper bound is obtained. A optimal feedback bits expression are derived to minimize the rate loss caused by limited feedback and channel delay. The numerical results show that the rate loss reduces when the number of feedback bits increases and the channel delay decreases. Meanwhile, the rate loss value reaches to a fixed value when feedback bits increase gradually. On the other hand, when the channel delay increases gradually, the rate loss can be improved little by the increasing of feedback bits. Lastly, as SNR increases, the system performance with the imperfect CSI improves more slowly than that with the perfect CSI.