Effect of Decentralized Congestion Control on Cooperative Systems

Vehicular cooperative systems are expected to provide a promising solution for enhancing active safety of vehicles. It requires stable and secure wireless communications for mutual information exchange among vehicles. In order to realize stable and secure communications, packet loss due to collisions need to be suppressed and communication apparatus should be ensured to perform proper cryptographic verification of packets. Because the hardware constraints in cooperative systems allow only a limited rate for cryptographic processing of packets, congestion control acts as a key technology to solve these challenges. This paper proposes a congestion control algorithm for vehicular cooperative systems to control the packet reception rate at a communication apparatus of a vehicle. The proposed algorithm is evaluated quantitatively by network simulation. The results show that the proposed algorithm can stabilize the packet reception rate by controlling the packet transmission rate on surrounding vehicles in a decentralized manner.