Investigation on Data Signal Muting to Improve Channel Estimation Accuracy in Downlink Coordinated Multiple-Point Transmission in LTE-Advanced

Abstract

Accurate channel estimation for multiple cells is essential in downlink coordinated multi-point (CoMP) transmission/reception. Therefore, this paper investigates a technique to improve the channel estimation for downlink CoMP in Long-Term Evolution (LTE)-Advanced. In particular, the performance of data signal muting, i.e., muting data signals that collide with the channel state information reference signal (CSI-RS) of a neighboring cell, is evaluated considering various CoMP schemes and intra-eNodeB and inter-eNodeB CoMP scenarios. In a multi-cell link level simulation, coordinated scheduling and coordinated beamforming (CS/CB) CoMP is employed. The simulation results show that data signal muting is effective in improving the channel estimation accuracy, which is confirmed by numerical analysis. Simulation results also show that it is effective in improving the throughput performance, especially for sets of user equipment at the cell boundary. Furthermore, the tradeoff relationship between accurate channel estimation by muting larger numbers of data signals and a high peak data rate, i.e., low overhead, is investigated. It is shown that when the number of coordinated cells is set to three, the CSI-RS reuse factor is set to three, and the well-planned CSI-RS pattern allocation is employed, the improvement in performance is almost saturated in a synchronized network.