Transmission Power-Control Certificate Omission in Vehicular Ad Hoc Networks

The frequent dissemination of safety-related beacons among neighboring vehicles in VANET is fundamental for cooperative awareness. Nevertheless, this has over the years raised a major security concern hence the current state-of-the-art requires all safety-related beacons to carry a certificate and a digital signature as a security mechanism to ensure authenticity and integrity. Unfortunately, this security mechanism is characterized by an increase in the size of a beacons payload which as a result, induces an overhead in communication under dense traffic conditions.

Several works have been published in the literature investigating how to reduce this overhead without compromising the level of security achieved, as well as vehicle cooperative awareness. The Neighbor-based Certificate Omission scheme, which conveys the general idea of a vehicle attaching a certificate to its beacon based on changes it observes from its neighboring table was proposed to address this issue. However, on evaluating the scheme under a dense traffic scenario, it was observed that the scheme reduced the level of achieved cooperative awareness among vehicles as it was unable to obtain a fair balance between the number of incurredcryptographic packet loss(packets dropped because the vehicle had no corresponding certificate to verify it) andnetwork packet loss(packets dropped because of network channel congestion).

In this paper, we propose a Transmission Power-control Certificate Omission scheme, which seeks to achieve a better balance between the number of incurredcryptographic packet loss (CPL)andnetwork packet loss (NPL)to maximize vehicle cooperative awareness even under dense traffic conditions. Unlike previously proposed schemes, we efficiently control channel load by adopting a congestion detection and congestion control algorithm in our scheme. The simulation results indicate that our proposed scheme can achieve a better balance between the number of incurred CPL and NPL and can maximize vehicle cooperative awareness even under dense traffic conditions.