Field Experimental Results of E-UTRA Downlink with Precoding and Non-Precoding MIMO

This paper investigates the effect of precoding in multiple input multiple output (MIMO) transmission from the viewpoint of transmitter antenna configurations, i.e., space diversity (SD) or polarization diversity (PD), in field experiments using the Evolved UMTS Terrestrial Radio Access (E-UTRA) experimental system. The field experimental results show that there is no performance gap between with and without precoding irrespective of the antenna configuration in a non-line of sight (NLOS) environment when a common precoding vector is applied over the entire signal bandwidth of 18 MHz and the maximum likelihood detection with QR-decomposition and M-algorithm (QRM-MLD) based algorithm is applied at the receiver. In a high correlation channel as observed in a line of sight (LOS) environment, there is also no performance gap between with and without precoding. However, in the high received SINR region, the throughput performance of the precoding with the PD configuration is worse than that without precoding since decoding errors occurred in both codewords, which are mapped onto two different transmitters, due to a significantly high received power gap between vertically and horizontally-polarized antennas.