Least square channel estimation for large-MIMO multi-cell downlink with reduced number of pilots

Channel estimation is key to enabling effective multiuser transmission in multiple-input multiple-output cellular networks. Thanks to technology advances and a shift to higher frequency carriers, recently there is an increasing interest in using very large antenna arrays at both ends of a wireless link, which is known as massive MIMO. In this work the problem of reducing large overhead due to pilot transmission for estimating massive MIMO channel elements in the uplink of a time division duplex (TDD) system with pilot contamination is considered. Through an analytical framework, a modified least-square (LS) algorithm is proposed, which requires less numbers of pilots than number of unknown channel elements that does not sacrifice system performance. Simulation results show the effectiveness of the proposed algorithm in terms of reducing the numbers of pilot terms with insignificant sum-rate loss.