Reducing Collision Probability in Sensing-Based SPS Algorithm for V2X Sidelink Communications

Sensing-based semi-persistent scheduling algorithm was developed by 3GPP as the standard for distributed resource selection in V2X sidelink communications. Sensing before resource selection largely reduces collision probability. However, we found that considerable collisions can happen if user equipments use different resource reservation intervals. An enhancement is proposed in this paper to prevent collisions. The proposed enhancement requires only simple computation and does not need additional information to be transmitted in sidelink control information. Simulations are conducted and results show that the improvement is significant. For our simulation scenario, the collision probability can be reduced by more than 77% under perfect channel condition. When channel condition is taken into consideration, the packet reception ratio can be improved by more than 6.41%.