roughput. The throughput is aver- aged over a time of 500 ms. A patch antenna is used in both the BTS and UE. The throughput is more than 4.8 Gbps in the downlink in 20% of the environment when the Figure 11.28 CDF of downlink throughput with the same Tx/Rx antenna configuration. Rank 8 16 QAM R = 0.5 Rank 4 64QAMR = 0.8 Rank 2 64QAM R = 0.8 Rank 8 QPSK R = 0.5 Rank 4 16 QAM R = 0.5 Downlink throughput (Gbps) 11 Measurements Figure 11.29 CDF of downlink throughput with OMNI Rx antenna configuration. Rank 4 64QAMR = 0.8 Rank 8 16QAM R = 0.5 Rank 2 64 QAM R = 0.8 Rank 8 QPSK R = 0.5 Rank 4 16 QAM R = 0.5 Downlink throughput (Gbps) MCS is configured as Rank-4 64-QAM with a coding rate of R = 0.8. However, Rank-8 transmission is not effective in this environment, since it achieved only up to 4.5 Gbps instantaneously. The spatial correlation of BTS and UE should be low enough to support higher order MIMO. In the first step, to make the spatial correlation low on the UE side, the UE antenna is changed to an OMNI antenna. Figure 11.29 shows the CDF of the downlink throughput in the OMNI antenna configuration in the UE. However, the result is like achieving only 2.4 Gbps instantaneously and degraded compare to the result of Figure 11.28. This is because the spatial correlation of the BTS side is still high even when the correlation of the UE side is changed. In addition, the antenna gain is degraded by -11 dB due to the change in the UE antenna configuration. However, this antenna gain degradation is unavoidable when the OMNI antenna is used. In the second step, to make the spatial correlation low on both the BTS and UE side, the UE keeps using the OMNI antenna, and the space of the BTS antenna branch is changed to 101 in the horizontal direction and 6.61 in the vertical direction. Figure 11.30 shows the CDF of the downlink throughput in the configuration. The correlation is low enough, achieving more than 4.8 Gbps even in Rank-8 of 64-QAM R = 0.8, as well as Rank-4 64-QAM R = 0.8. The characteristics of both Rank-4 and 