QPER is inserted into the coaxial links between real UEs and base stations (gnodeB,enodeB,AP) or base station emulators to simulate essential effects of signal propagation through open space, such as the free space path loss, slow or fast fading, shadowing, drop-outs and various handover situations. Various signal propagation models can be applied to calculate signal strength, channel coefficients, and other radio channel effects (Doppler, Delay, Multipath etc.). Optionally also MIMO effects can be generated with additional SW controlled phase shifter. A replay function for drive tests, enables to use the measured values of a drive test to replay the experienced scenario in the lab. The QPER can also be used in combination with the LTS offering an automated environment comprehending both load and changing air interface charateristics to replay real world scenario’s.