Research Of Channel Reservation Scheme Based On Dcf Mechanism For Wave Network

Wireless access in vehicular environments (WAVE) network is an important technology in vehicular communication network, more over is an important part of intelligent transport systems (ITS). The transmission of safety information and unsafe information is realized by the wireless communication of the vehicles and between vehicle and roadside infrastructure in the WAVE network. Safety information is mainly used for accident avoidance, road warning and other security applications, while the non security information is mainly used for Internet access, entertainment services, and other non security applications. Therefore, the key problems in the WAVE network research are how to optimize the channel resource allocation, and realize the coordination of safety information and non safety information transmission control, so as to improve the performance of WAVE network.This dissertation is based on the DCF mechanism, and it is the key research object that the specific process and method of the node through control channel (CCH) reserving service channel (SCH) in the WAVE network. And the performance of the channel reservation scheme based on DCF mechanism is analyzed.Firstly, through the research and analysis of the existing problems in the channel reservation scheme of WAVE network technology standards and other related MAC protocol, a channel reservation scheme is proposed which is based on DCF mechanism in WAVE network. All nodes can immediately switch to the SCH for related business, after reserving SCH successfully by sending request for send (RFS) packet on CCH.Secondly, according to the probability of the nodes competing in SCH on CCH, the system model of channel reservation scheme is constructed which is based on DCF mechanism. The Markov chain model and matrix analysis method is used to obtain probability of nodes transmitting packet and the steady state probability of the system. Thus, the important index of the performance of the system is obtained, that is, average transmission delay in node transport data and SCH throughput.Finally, the performance of the channel reservation scheme is analyzed which is based on DCF mechanism in the WAVE network. The results show that the performance has no negligible impact that RFS packet generation rate and minimum contention window for the channel reservation scheme based on DCF mechanism. A channel reservation scheme based on DCF scheme in WAVE network is compared with the IEEE 1609.4 protocol and the variable CCH interval protocol. Performance comparison results show that under the condition of the given system parameters, the proposed channel reservation scheme can reduce the average transmission delay by about 20%, and the throughput of SCH can be improved by about 25%, compared with the channel reservation schemes for two other protocols.