 XPD-MMSE: Equal power allocation Co-Pol: SVD precoding: Equal power allocation Co-Pol: MMSE: Equal power allocation Averaged Received SNR Over Time and Frequency (dB) Figure 11.28 Performance gains with SVD precoding-dual stream-equal power allocation. © 2009 by Taylor & Francis Group, LLC Early Real-Time Experiments and Field Trial Measurements Adaptive Transmission Scheme XPD-SVD precoding: Water-filling XPD-MMSE: Equal power allocation Co-Pol: SVD precoding: Water-filling Co-Pol: MMSE: Equal power allocation Average Received SNR Over Time and Frequency (dB) Figure 11.29 Water-filling power allocation gains. is even more relevant if suboptimal decoding algorithms, such as a zero-forcing decorrelator or an MMSE filter, are used at the receiver because these algorithms commonly employ a channel inversion step, which boosts the noise power after sig- nal processing. The condition number of the channel is an indicator of the resulting noise enhancement. A high condition number means a higher noise enhancement, and a lower condition number means a lower noise enhancement. Channel correla- tions because of LOS channel conditions tend to increase the condition number of the matrix. Referring to Equation (11.1), the worst-case channel condition in an LOS copo- larized channel occurs when all the channel coefficients are equal to a constant h, Fixed VS. Adaptive Schemes XPD-SVD precoding: Equal power allocation XPD-SVD precoding: Water-filling Co-Pol: SVD precoding: Equal power allocation Co-Pol: SVD precoding: Water-filling Average Received SNR Over Time and Frequency (dB) Figure 11.30 Water-filling power allocation upper bound. © 2009 by Taylor & Francis Group, LLC Long Term Evolution: 3GPP LTE Radio and Cellular Technology Theory vs. Practice SVD. waterfilling. Cross polarized LTE codebook. MS. Cross polarized SVD. waterfilling. Co polarized LTE codebook. MS. Co polarized MMSE.EPA. Cross polarized MMSE.EPA. Co polarized Average Received SNR Over Time and Frequency (dB) Figure 11.31 Codebook precoding throughput gain