Phase Noise in Beamforming

In this article we examine the effect of phase noise on a multi-antenna beamforming system. The effect is quantified in terms of error vector magnitude (EVM). It is shown that using independent phase noise sources improves EVM performance in the main lobe. It is further shown that when forming beams using antenna amplitude attenuation (tapering) for groups of correlated noise sources, lowest EVM is obtained when correlated noise sources are assigned to tapered amplitudes in a way which minimizes the differences between the sums of the tapering coefficients of the groups. Bounds for the variance of the phase noise in the main lobe are provided. Further a method achieving secure communication by forming a secure beam by adding uncorrelated phase noise to the antenna elements is presented.