Characterising Vehicle Suspension Variations in Millimetre Wave V2I System

Abstract

This paper investigates the effects of antenna vibration occurring due to suspension variation during the movement for vehicle-to-infrastructure (V2I) communication by developing a two dimensional (2D) model. With highly directional antennas fitted on a car's rear bumper and at a base station (BS), different beamwidths from 10° to 50° are investigated for a moving vehicle at 70mph. The gain sensitivity of the radiation pattern and the micro-Doppler shift are modelled for suspension variations between 5cm and 20cm. The analysis has been performed based on the observed angle of arrivals (AoA) at the receiver antenna in the elevation plane. The gain sensitivity represents the BSs' main lobes' misalignments and receiver antennas' radiation patterns at 26GHz. The results reveal a significant impact on gain sensitivity during the first 200m of movement away from the BS. Furthermore, the total Doppler shift increases due to the micro-Doppler with vertical displacements from the suspension variation. However, this can be mitigated if the beamwidth increases relative to the link budget or the BS height increases. The 2D model is validated by utilising accelerometer data recorded whilst the vehicle is moving at 70mph on a motorway, by extracting the displacements and computing the gain sensitivity.

On Antenna Mounting Position for 6G Vehicular Communications

“…The variations in (10) cause beam misalignments and, consequently, beamforming gain loss. Assuming both Tx and Rx are equipped with the same antenna array, the total beamforming gain can be expressed as…”

“…where the pointing angles ( θ, φ) are only affected by the roll δ ψ and pitch δ phi variations in (10). Both Tx and Rx are equipped with a squared uniform planar array (UPA) with N a × N a elements.…”

“…The authors in [9] studied these effects on Doppler spread and channel estimation. The study in [10] investigates the impact of antenna vibration during the vehicle's mobility in a vehicle-to-infrastructure (V2I) scenario. The results show that loss due to beam misalignment increases for narrower beams, shorter Tx-Rx distance, or for a lower height of the base station.…”