Vehicle Positioning Requirements for Location-Aware Beamforming in 5G UDN

Location-Aware Beamforming (LAB) in Ultra-Dense Networks (UDN) is a breakthrough technology for 5G New Radio (NR) millimeter wave (mmWave) radio in general and Vehicle-to-everything (V2X) communication in particular. Directional links with narrow antenna half-power beamwidth (HPBW) and massive multiple-input multiple-output (mMIMO) processing systems allows to increase transmitter and receiver gains and thus facilitates to overcome high path loss in mmWave. Well known problem of pencil beamforming is in construction of precoding vectors at the transmitter and combining vectors at the receiver during directional link establishing and maintaining. It is complicated by huge array size and cumbersome channel state information (CSI) exchange, which is especially time consuming for vehicles. Knowledge of transmitter and receiver location could significantly alleviate directional link establishment. Purpose of this research is positioning requirement development for vehicles with LAB. Approach used is survey of current state-of-the art in the field of LAB and analytical modeling. Findings of research include channel coherence time interdependence on the vehicle speed, beamwidth, pointing error and positioning service level. Practical implications of results are in justification of vehicle positioning requirements for LAB in a separate link.