ent is much easier to emulate in a reverberation chamber. The reverberation chamber is also a reference environment-a reflective reference environment with Rayleigh statistics that is much more suitable for devices with small antennas than the anechoic reference environment. The reverberation cham- ber has the advantages that it can be made much smaller and that the measurements can be performed much faster than in an anechoic chambers. Another very large advantage, especially important for 3GPP LTE, is the possibility to make direct measurements in the reflective (Rayleigh) reference environment of diversity gain and MIMO capacity for products with multiple antennas. The alternative "drive test" has several drawbacks: unreliable (one can never be sure to drive exactly the same route and through the same environment more than once); expensive (one needs to make simultaneous measurements for each of the multiple antennas in the terminal as well as for a reference antenna); and time consuming. © 2009 by Taylor & Francis Group, LLC Measuring Performance of 3GPP LTE Terminals We will see in this chapter that, for the first time ever, the reverberation chamber makes it possible to do repeatable system throughput tests in a reflective environ- ment as well as completely new tests of importance for 3GPP LTE technologies- for example, multiuser MIMO (MU-MIMO) and scheduling tests that are mainly only simulated in software today. System throughput tests could, as time passes, become more important for designers of 3GPP LTE terminals and small base sta- tions than the traditional TRP and TIS tests done in anechoic or reverberation chambers because they show the actual performance in the downlink and uplink in a Rayleigh environment. 12.1.2 Brief Background on Reverberation Chambers For about 30 years, reverberation chambers (or mode-stirred chambers) have been used to test how much electrical devices radiate (normally referred to as electro- magnetic compatibility [EMC] measurements) to avoid interference with other electr