Sensing-Based Beamformed Resource Allocation in Standalone Millimeter-Wave Vehicular Networks

TL;DR

This work addresses uncoordinated, sidelink resource allocation for NR V2X in FR2 mmWave, where directional beamforming and high mobility create collisions and hidden/exposed node issues. It introduces a directional, SCI-assisted resource allocation scheme (DBRA) that uses primary and paired transmission directions to sense resource occupancy and guide selection within sensing/selection windows. Through mmWave V2X simulations, the approach shows significant collision reductions compared with baselines that do not configure SCI transmissions, with further improvements realized with larger antenna arrays and moderate network loads. The findings suggest a practical path to robust standalone NR V2X resource management in dense urban mmWave vehicular networks, with future work on mobility, sensing errors, and analytical performance modeling.

Abstract

In 3GPP New Radio (NR) Vehicle-to-Everything (V2X), the new standard for next-generation vehicular networks, vehicles can autonomously select sidelink resources for data transmission, which permits network operations without cellular coverage. However, standalone resource allocation is uncoordinated, and is complicated by the high mobility of the nodes that may introduce unforeseen channel collisions (e.g., when a transmitting vehicle changes path) or free up resources (e.g., when a vehicle moves outside of the communication area). Moreover, unscheduled resource allocation is prone to the hidden node and exposed node problems, which are particularly critical considering directional transmissions. In this paper, we implement and demonstrate a new channel access scheme for NR V2X in Frequency Range 2 (FR2), i.e., at millimeter wave (mmWave) frequencies, based on directional and beamformed transmissions along with Sidelink Control Information (SCI) to select resources for transmission. We prove via simulation that this approach can reduce the probability of collision for resource allocation, compared to a baseline solution that does not configure SCI transmissions.

Figures (8)

• Figure 1: Vehicles antenna arrays setting.
• Figure 2: Flowchart for the Selection Window in dbra.
• Figure 3: Illustration of the Sensing and Selection Windows in dbra.
• Figure 4: Maps of the urban scenarios. White dots indicate the initial positions of the vehicles, while red and blue lines represent the routes of the vehicles in the corresponding lanes.
• Figure 5: vs. $n_{tx}$ in the 2W-LD scenario, with PRFS-1 and $D=20$ Mbps.