Blind downlink channel estimation of multi-user multi-cell massive MIMO system in presence of the pilot contamination

摘要

The pilot contamination is a challenge of channel estimation in multi-user multi-cell massive Multiple Input Multiple Output (MIMO) system. In the Time Division Duplexing (TDD) technique, the uplink estimated channel is used for pre-coding the downlink signals, which leads to converting the downlink channel estimation to channel gain estimation. The classical method for the channel gain estimation is pilot-based estimation, which has several problems such as low spectral efficiency. In this paper, we propose a blind method for estimating the downlink channel gain in the TDD based multi-cell multi-user massive MIMO system in the presence of the pilot contamination. In the proposed method, we show that the average energy of the downlink received signal to each user is a function of the channel gain, thus by calculating this average energy using samples of the received signal, the channel gain is estimated. The convergence of the proposed method is analyzed theoretically, and the performance of the proposed method is evaluated with simulation results. (C) 2020 Elsevier GmbH. All rights reserved.