RF impairments of vector modulators in wireless MIMO receivers

Multiple-input multiple-output (MIMO) systems enable significant improvements for the wireless links in communication networks. If parts of the spatial signal processing of these multiple antennas are executed in the analogue RF front-end, power consumption, system size and costs of the system are minimised but key benefits of MIMO can still be exploited. However, analogue RF circuits are affected by impairments. These effects are analysed and modelled for a direct down-conversion receiver using maximum ratio combining (MRC) in the RF front-end. The errors arising from silicon integration are modelled and their effect on the wireless communication system is analysed. It is shown that technology impairments of RF spatial signal processing do not limit the wireless link performance with respect to the received signal-to-noise-ratio (SNR) and the bit error rates (BER) in practical cases.