The effect of phase shifter errors on the performance of millimeter wave beamforming

Due to the limitation in cost and power supply, RF beamforming with low precision phase shifter, instead of baseband beamforming, is widely used in millimeter wave system. In IEEE 802.11 ad, beamforming is based on a codebook with 2-bit phase shifter. The inadequate precision degrades the link performance. This paper analyses the performance loss due to the limited precision of phase shifter and simulation is performed to validate the result of analysis. At the same time several conclusions are obtained: (1) with the increase of the precision of the phase shifter, the performance of beamforming is improved, resulting a better sidelobe suppression and main lobe gain; (2) The gain loss brought by the low precision phase shifter is limited, a 3-bit phase shifter can get a performance close to the ideal one. We conclude that precision of the phase shifter is not the key factor that affects the performance of millimeter wave beamforming. More attention should be focused on other aspects, such as the channel estimation, acquisition of optimal beamforming weights, etc.