e received power for a reference antenna with known radia- tion efficiency. The radiation efficiency measurement procedure is similar to the calibration mea- surement procedure described earlier and can be summarized in the following steps: Perform the calibration measurement procedure as described in the previ- ous section, including the calculations of mismatch and reference transfer function. Replace the reference antenna with the test antenna and repeat the measure- ment procedure (i.e., sample S11, S21, and S22) for each stirrer position. If the fixed-measurement antenna is the same as in the calibration measurement, there is no need to remeasure S11, and only S21 and S22 need to be samples. Calculate the antenna mismatch and radiation efficiency for the test antenna as described in the following. © 2009 by Taylor & Francis Group, LLC Measuring Performance of 3GPP LTE Terminals Equivalently to the calculations for the preceding reference transfer function, the test antenna mismatch, mismatch power correction, and average transfer func- tion are calculated as shown in the following equations: (12.17) (12.18) (12.19) The radiation efficiency is then directly given by (12.20) and the total radiation efficiency is given by (12.21) 12.3.2 Measurement of Total Radiated Power For active test units, the TRP is determined by the power output from the ampli- fier and the radiation efficiency of the antenna. The TRP is therefore often used as a performance parameter, especially when a cabled connection to the antenna port is difficult. The following description is based on measurements of user equipment (UE) but can be modified to measurements of any kind of equipment by using the appropriate instrumentation. The TRP measurement procedure is similar to the radiation efficiency proce- dure described earlier; the main difference is that the network analyzer is replaced by a base station simulator and power meter. The base station simulator is used to establish and maintain a connection to the UE and control its traffic c