Singular Value Distribution of the Measured Channel 11.2.4.2 SINR Distribution 11.2.4.3 Measured Throughput with Link Adaptation 11.2.4.4 Measured Rates with Different Antenna Configurations 11.2.5 Outdoor Results 11.2.6 Discussion of Results Real-Time Multiuser Downlink Measurements 11.3.1 Fair and Efficient Scheduling 11.3.2 Multiuser Measurement 11.3.3 Discussion of Results Polarization Multiplexing for Multiuser Downlink 11.4.1 2 x 2 Cross-Polarized MIMO Channel 11.4.2 Measurement Setup 11.4.3 Single-User Throughput Analysis 11.4.3.1 Channel Characteristics 11.4.3.2 Channel Condition Number 11.4.3.3 SVD Precoding 11.4.3.4 Spatial Water Filling 11.4.3.5 Precoding with Unitary Codebooks and Bit Loading © 2009 by Taylor & Francis Group, LLC Early Real-Time Experiments and Field Trial Measurements 11.4.4 Multiuser Scheduling 11.4.4.1 XPD Antennas for Multiuser Scheduling 11.4.4.2 Impact of More Users on System Performance 11.4.5 Discussion of Results 11.4.5.1 Summary of Field Trial Results References 11.1. Description of a Scalable MIMO- OFDM Experimental System for Real-Time Measurements The experimental test bed that allowed the first-ever multiple input, multiple out- put orthogonal frequency division multiple access (MIMO-OFDM) transmis- sion according to the new 3rd Generation Partnership Project long term evolution (3GPP-LTE) air interface was planned at the end of 2005. This was during the early stages of the LTE standardization. Since that time, the standardization body has agreed to a few minor changes that have no impact on the validity and relevance of the measurement results obtained with the LTE demonstration system described in this chapter. Table 11.1 gives an overview of the system parameters of the experimental sys- tem and, for comparison, the current parameter values of the standard. The main change has been in the definition of a physical resources block (RBs) from 25 sub- carriers over 7 OFDM symbols to 12 subcarriers and 14 OFDM symbols, which in spirit has exchanged time against frequency g