On the Optimal CSI Feedback Rate of Downlink MIMO Systems Using Multiple Receive Antennas in Cellular Networks

A downlink cellular network is considered, in which multiple-antenna base stations (BSs) are distributed following a homogeneous Poisson point process. Each BS serves a single user equipped with multiple-receive antennas. The partial channel state information is achieved at the transmitter using a limited feedback. The singular-value-decomposition-based precoding is performed for the downlink spatial multiplexing. In this letter, the optimal number of feedback bits that maximizes the net spectral efficiency is investigated. The net spectral efficiency is defined to measure the net profit achieved by using limited-feedback-based spatial multiplexing. By extending previous studies, the effect of using multiple-receive antennas on the optimal number is investigated. Specifically, the scaling rate of the optimal number is newly obtained for more than one receive antenna.