Experimental Evaluation on SU-MIMO Transmission with Closed-Loop Precoding in LTE-Advanced Uplink

This paper presents the laboratory experimental results employing LTE-Advanced testbed for the evaluation of the throughput performance of closed-loop single-user MIMO transmission at the uplink single carrier (SC)-FDMA radio access in LTE-Advanced. The throughput evaluation includes the impact of estimation accuracy of MIMO channel responses which are derived from the sounding reference signal (SRS) and used for the precoding vector (PV) selection and adaptive modulation and coding (AMC) at the base station. The experimental results elucidate that the maximum throughput of 200 Mbps is achieved in multipath fading environments by using 2-by-2 spatial multiplexing and carrier aggregation with 2 component carriers. The results also clarifies that the estimation accuracy of MIMO channel responses using the SRS has a greater influence on modulation and coding scheme (MCS) selection for AMC than PV selection due to the fact that the throughput performance employing AMC is clearly degraded by approximately 20% while the block error rate for Rank-1 closed-loop transmit diversity is not degraded very much when the transmission power ratio of SRS to data channel is reduced from 0 dB to -10 dB.