work analyzer Figure 12.10 Setup for measuring a six-element MIMO antenna. © 2009 by Taylor & Francis Group, LLC Measuring Performance of GPP LTE Terminals terminated in 50 Q. The S parameters between the connected port in the MIMO configuration and each of the fixed wall-mounted antennas, used for polarization stirring, are measured for all positions of the platform and mechanical stirrers and all frequency points. The measurement procedure is then repeated for every antenna port, using exactly the same platform and stirrer positions. Thus, the field inside the chamber is exactly the same when measuring every port. The complex transmission coefficients S21 between the connected port and each of the fixed wall antennas, as well as the reflection coefficients S11 of each wall antenna and S22 of the test object ports, are stored for every stirrer position and frequency point. Finally, we connect the reference antenna to the network analyzer and perform the same measurements. In a small chamber, it is advantageous to use frequency stirring (averaging) to improve accuracy. In such cases, we correct the complex samples of S21 with mismatch factors due to both S11 and S22 before frequency stirring, as explained in Kildal and Carlsson [52, Equation 1]. We also normalize the corrected S21 samples to a reference level corresponding to 100% radiation effi- ciency. This is obtained from the corrected S21 samples measured for the reference antenna and its known radiation efficiency. We refer to these corrected and normal- ized samples of S21 as normalized S21 values. The normalized S21 values can now be used to calculate the MIMO capacity as described previously. 12.3.7 Measuring System Throughput Multiantenna solutions at the terminal or base stations will be key technologies in 3GPP LTE to ensure high throughput and low delays to users also at the cell edge. There are no accepted or well-known standards today to measure system through- put of multiantenna solutions. One of the reasons for this is that established stan- dar