Performance Analysis of Beam Sweeping in Millimeter Wave Assuming Noise and Imperfect Antenna Patterns

Beam alignment is an important component of millimeter wave communication systems, which use analog beam steering.We analyze the performance of beam alignment methods based on the hierarchical beam sweeping that are adopted in IEEE 802.11ad and IEEE 802.15.3c. Previous work studies misalignment probability due to thermal noise or antenna gain fluctuation alone. At the early stage of the alignment process, however, both effects are important. We incorporate both effects and derive probability of misalignment not only with respect to the best path but also to secondary ones. Our analysis can capture the misalignment severity in terms of power loss with respect to the perfect alignment case. Numerical examples show that line-of-sight channels are more constrained by the thermal noise, while the non- line-of-sight channels are more constrained by the antenna gain fluctuations.