Field Experiments on Closed-Loop SU-MIMO Transmission Considering Effect of Antenna Configurations in LTE-Advanced Uplink

This paper presents experimental results to clarify the throughput performance and effective location probability for closed-loop single-user (SU)-MIMO transmission considering the effect of antenna configurations in the LTE-Advanced uplink. The achievable throughput performance with adaptive modulation and coding (AMC) and hybrid automatic repeat request (HARQ) is evaluated using the implemented LTE-Advanced transceivers, where the total transmission power and bandwidth per component carrier of a mobile station (MS) are set to 23 dBm and 17.28 MHz, respectively. The experimental results show that when 2-by-2 Rank-2 SU-MIMO, i.e., spatial multiplexing, is applied, a cross-polarized antenna configuration exhibits better throughput performance compared to that using co-polarized antennas and the location probability for achieving throughput greater than 200 Mbps is clearly increased. Furthermore, we confirm that the throughput performance using cross-polarized antennas is very robust against the variation in MS antenna angles irrespective of the rank values for SU-MIMO transmission. The experimental results also show that 2-by-2 Rank-2 SU-MIMO using the cross- polarized antennas improves the throughput performance compared to 1-by-2 SIMO at the location probability of greater than 60% even when the MS antenna gain imbalance level of 12 dB is considered.