AnalogMUSIC: A Concurrent Beam Training Scheme for Multiple Users in mmWave Systems

In this paper, a multi-user concurrent beam training scheme, named AnalogMUSIC, is designed for mmWave systems with a single radio frequency (RF) chain. In AnalogMUSIC, a one-RF chain based multiple signal classification (MUSIC) algorithm is developed for accurate direction estimation, where the training beams are switched in a time-division manner. To pursue a short training time, the training beams are switched at rough directions predefined by a coarse- resolution codebook. We prove that the traditional MUSIC algorithm can be achieved in the frequency domain. For orthogonal frequency division multiple access (OFDMA) systems, the multi-user training signals can be decoupled in the frequency domain. Thus, AnalogMUSIC achieves the concurrent beam training for multiple users by allocating different subcarriers to different users. To further adapt the number of switched training beams to various channel conditions, two coarse-resolution codebooks and a beam mapping mechanism are designed. Extensive simulations show that AnalogMUSIC can effectively improve beam training accuracy and substantially reduce delay overhead, compared with the existing schemes.