Refining Packet Collision Check in Resource Allocation for NR Sidelink Mode 2.

To enable direct vehicle-to-vehicle communication in 3GPP New Radio (NR) Sidelink Mode 2, each vehicle must autonomously select radio radio resource to use by using Sensing-based semi-persistent-scheduling (SB-SPS) algorithm. SB-SPS helps avoid packet collisions through determining whether or not selecting a particular resource inside the resource selection window will cause a collision with other vehicle’s transmission. This paper shows that such check is insufficient because packet collisions can still occur beyond the selection window due to various combinations of resource reservation periods allowed in the NR Sidelink Mode 2 in Release 16. In order to solve the problem and further reduce packet collisions currently unchecked by SB-SPS, a resource scoring method and a Received Signal Strength Indicator (RSSI)-based scoring assistance scheme are proposed. Simulation experiments show that the proposal reduces the number of total packet collisions and the number of consecutive collision events by 15-25% compared to SB-SPS.