Multi-frequency Coordination Based Beam Management Scheme for 6G C-V2X Sidelink Communications

Abstract

Direct communications among vehicles to exchange massive sensor data is an essential component to achieve fully autonomous driving, which can be enabled by Vehicle-to-Everything (V2X) sidelink communications in the mmWave frequency band. However, in a dynamic vehicular environment, frequent beam tracking for obtaining time-varying channel information and maintaining accurate beam alignment incurs high training overhead. To reduce the overhead, a multi-frequency coordination-based beam tracking (MFC-BT) scheme is proposed and formulated as a compressed sensing recovery problem. In the training phase, the optimal training beams are designed by minimizing the Cramér-Rao lower bound (CRLB) of channel spatial angle parameters estimation. The prior angle probability distribution is determined by the spatial congruence with sub-6 GHz channel as well as the temporal correlation of V2X channel. In the estimation phase, sub-6 GHz channel spatial information and previous angle information are extracted as weights to estimate the best beam pair. Simulation results show that compared to the conventional tracking method, the proposed scheme can reduce the training overhead by 48% to achieve a 38.9% effective rate improvement, which is significant at low SNR.