Adaptive optimization of QoS constraint transmission capacity of VANET

Abstract Safety applications would be one of the most important on-board implementations in Vehicular Ad-hoc Network (VANET). Broadcasting the Basic Safety Message (BSM) periodically could help drivers increase their awareness range for preventing casualties of traffic accidents or reducing the number of traffic accidents. Usually, the safety applications have more stringent performance requirements (e.g. time delay and reliability) than other kinds of applications. However, because the vehicle density and speed are both changed frequently, the optimal network transmission parameters should not remain the same. So, setting constant transmission parameters in all conditions may cause problems, such as channel congestion, packet collisions and so on, which could degrade Quality of Service (QoS) of safety applications. For the purpose of maximizing the transmission capacity and keeping the application-level QoS of safety applications meeting their requirements, this paper proposes an optimization scheme with standard Particle Swarm Optimization (PSO) to adjust transmission parameters dynamically. The experimental results show that the optimized transmission parameters can get better results on transmission capacity and awareness probability compared with the transmission parameters which are used in real testbeds.