hed to 'medium' and a jump in second stream throughput can be seen with the first stream still carrying most of the data. At about 120 seconds time, the correlation is switched to 'low' and both streams are now carrying 40 Mbps with the total dual-stream throughput of 80 Mbps. Thus, depending on the level of antenna correlation throughput can vary between 40 to 80 Mbps, at fixed average SNR of 25 dB. From the condition number, 1 shown on the right-hand side axis, it can be seen that when the correlation is high the power difference between the first and second substreams is in the order of 25 dB which indicates that the SINR of second substream is about 0 dB since average SNR is 25 dB. For low correlation, the average condition number drops to below 10 dB; in this case the higher signal power of the second substream allows sending and detecting two streams simultaneously. A logical question for practical deployments is that of how to minimize antenna correlation. While this is in general difficult, one simple rule is to use cross-polarized eNodeB and UE antennas whenever possible. A drive test example with two different antenna setups is shown in Figure 12.43 to illustrate the impact. In the example, the same drive test route in an unloaded test network is driven twice, once using two vertically polarized antennas at the rooftop of the measurement car and once using a custom-manufactured cross-polarized antenna with a near- omni-horizontal pattern. The result shows that the dual-stream usage of the cross-polarized antenna is noticeably higher improving the throughput distribution at the high-SNR regime (typically coinciding with line of sight). However, at low-SNR regime the throughput of the vertically polarized antennas is slightly better in the example measurement (the gain of the vertically polarized antennas was higher and was not compensated). Similar behaviour has been noticed in numerous other measurements and the practical conclusion for field deployments is that cross-polarized configuration provides ga