Joint Multi-Beam and Channel Tracking for mmWave Hybrid Beamforming Multi-user Systems

The millimeter wave (mmWave) technology will perform an important role in supporting multi-gigabit services. To compensate for significant path loss and penetration loss, more antennas are equipped to establish narrow beams and provide sufficient antenna array gains. In the meantime, the hybrid beamforming (HBF) structure is utilized to provide acceptable cost and energy consumption, which also flexibly supports multi-user scenarios. However, when the channel varies rapidly, efficiently tracking multiple paths or beam directions still faces difficulties. In this letter, a joint multi-beam and channel tracking scheme is proposed to efficiently perform the beam management for the mmWave HBF multi-user systems. The pilot allocation is optimized and the asymptotic performance of the proposed algorithm is analyzed. Numerical results indicate that the proposed algorithm can significantly improve the tracking performance under time-varying channels.