Abstract: A system for emulating an over-the-air channel for communicating with a device under test is provided. The system comprises an anechoic chamber having NA primary probes and NB secondary probes where NA>NB. The system also comprises a dividing module for dividing NA primary impulse responses {?nA} into NB subsets; and a defining module for defining NB secondary impulse responses {vnB} in terms of the primary impulse responses {?nA} and a set of NB complex sequences {?nB}. In the system, either the primary probes are downlink probes, the primary impulse responses are downlink impulse responses, the secondary probes are uplink probes and the secondary impulse responses are uplink impulse responses, or the primary probes are uplink probes, the primary impulse responses are uplink impulse responses, the secondary probes are downlink probes and the secondary impulse responses are downlink impulse responses.