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Recently, massive multiple-input multiple-output (MIMO) system has attracted tremendous research interests in wireless communications. Among various performance aspects and design problems regarding massive MIMO, precoding at the base station (BS) is one of the most important function components to ensure reliable downlink transmission. This paper provides a survey of linear precoding techniques for downlink transmission under both single-cell (SC) and multicell (MC) scenarios. In an SC scenario, a series of classical precoding techniques are reviewed and compared. In an MC scenario, massive MIMO suffers from pilot contamination problems, where orthogonal pilot sequences have to be reused among cells, leading to estimation errors of channel state information at the transmitter. Precoding techniques with and without the cooperation among BSs are reviewed and the cooperative precoding …