An Evasive Scheduling Enhancement against Packet Dropping Attacks in C-V2X Communication

Third Generation Partnership Project (3GPP) has standardized the Sensing-Based Semi-Persistent Scheduling (SB-SPS) as the radio resource allocation algorithm for Cellular V2X (C-V2X) sidelink communication Mode 4. The algorithm leverages on past resource use pattern and reservation information of neighbor vehicles to reduce the chances of packet collisions. However, the very predictability can be exploited by potential attackers to intentionally cause packet collisions in the predicted transmission locations in the resource plane. In this letter, we demonstrate that such packet dropping attack can cause the victim to become a 'ghost vehicle' to neighbors for a long duration. If used in highly safety-critical situations, the attack can push the victim into a situation of higher crash risk, which would be worse off than not having the C-V2X safety communication. Therefore, we propose an enhancement to the SB-SPS algorithm to guard against the attack by randomizing actually used resource locations to a certain degree. We demonstrate the effectiveness of the proposed enhancement through analysis and simulation, and discuss its cost aspect as well.