Degrees of Freedom of Downlink Single-And Multi-Cell Multi-User MIMO Systems With Location Based CSIT

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Multiple antennas facilitate the coexistence of multiple users in wireless communications, leading to spatial multiplexing and spatial division and to significant system capacity increase. However, this comes at the cost of very precise Channel State Information at the Transmitters (CSIT). The authors advocate the use of channel propagation models to transform location information into (possibly incomplete) CSIT. They investigate the resulting multi-user sum rate from a DoF (Degree of Freedom, high SNR rate pre-log, spatial multiplexing factor) point of view. For single-cell multiuser communications, they argue for a revival of SDMA (Spatial Division Multiple Access).