Field Experiments on Antenna Configuration Associated with Fading Correlation for Downlink Multi-User MIMO in LTE-Advanced

This paper presents field experimental results on a base station (BS) antenna configuration associated with the fading correlation when using 4-by-2 multi-user (MU) multiple-input multiple-output (MIMO) in the Long Term Evolution (LTE)-Advanced downlink. In field experiments conducted in urban and suburban areas, we consider four antenna configurations, i.e., combinations of cross-/co-polarized antennas with an antenna array/space diversity antennas. The field experimental results show that the cross-polarized antenna configuration with low and high correlated antenna pairs is very effective in achieving throughput of greater than 800 Mbps when 4-by-2 Rank-4 MU-MIMO is applied in a suburban area under line-of-sight (LOS) conditions. In an urban area, where the majority of the measurement course is under non-LOS (NLOS) conditions, the experimental results show limited improvement in throughput for Rank-4 MU-MIMO. In this environment, we also show that Rank-2 MU-MIMO employing a space diversity antenna configuration achieves relatively high throughput irrespective of the angular difference between spatially multiplexed mobile stations.