ding environ- ment). The problem when one wants to optimize the antenna configuration is that the fading in real environments is always changing and it is not possible to know if the results depend on changes in the environment or changes in the antenna con- figuration. It is also possible to measure diversity gain by measuring each antenna in the antenna configuration separately in an anechoic chamber. After the measure- ments, by using software it is possible to add any type of fading and then estimate the diversity gain [51]. This takes a relatively long time, on the order of 1-2 hours in total. A very efficient alternative is to use the repeatable Rayleigh distribution available in the reverberation chamber. The antenna configuration is positioned in the reverberation chamber, as shown in Figure 12.8. If possible, a multiport network analyzer is used to measure amplitude and phase of the different antennas in the antenna configuration and the three fixed antennas in the reverberation chamber S For a diversity antenna with two branches, S12 and S13 are measured simultaneously. Both these antenna branches will show a certain probability to have fading below a certain level, usually referred to as the cumula- tive distribution function (CDF). By choosing the best of the measured S12 and S13 at every point in time, one gets a CDF that is called selection combining. It is, of course, possible to use the S12 and S13 to get the CDF of any diversity scheme (e.g., Switch Network analyzer Figure 12.8 Left: drawing of the standard-sized Bluetest reverberation chamber, shown with open door. The drawing shows a setup for measuring diversity gain with a multiport network analyzer. Right: photo of 900-MHz dipoles used in the tests. © 2009 by Taylor & Francis Group, LLC Long Term Evolution: 3GPP LTE Radio and Cellular Technology maximum ratio combining [MRC]) because both amplitude and phase have been measured. However, in this section we use selection combining. By taking the difference between the CDF for either S12 or S13