Impact of the Undesired RF-IF Chain Effects on the LS-CMA based Beamformer in CDMA Mobile Communications

In mobile communications, nonideal operation of the RF-IF chain has significant effects on the signal received by the BS. Since most beamforming algorithms use the received signal parameters to steer suitable beam, any error or uncertainty cause significant degradation in beamforming performance. In this paper, effects of some of the most important RF-IF chain errors occurred in down conversion process are investigated theoretically as well as by simulation. Our investigations show that the error caused by the difference between down converters, has a significant effect on the beamformer performance. It is shown that the RF-IF chain phase and amplitude errors have a more significant effect on the beamformer performance than the other errors. Because of the higher sensitivity of the phase of the received signal, phase error has the most significant effect.