It should be noted that a network simulator is designed to test the performance of a single device under test: simulation is not normally appropriate for stressing the multi-user scheduler algorithm of the base station.
Multiple simulators can be used to simulate multiple base stations, and they may be coupled with faders to simulate multi-path interference/MIMO scenarios.
The benefit of testing in a laboratory environment, however, is that the tests are easy to repeat, and allow the operator to create any set of network conditions in order to stress-test a handset. Of course, no set of test scenarios can exactly mimic every possible condition in the live network. But the simulator plays a crucial part in the operator's overall strategy for assessing and validating the operation of terminals in the live network.
The author, Francois Ortolan is a Regional Wireless Specialist at Anritsu (EMEA).