Research Of Multi-Channel Mac Protocol Based On Edca Mechanism For Wave Network

In complicated WAVE network which has various service requirements, the throughput and delay of normal data transferring service should be guaranteed. The channel access delay jitter should be varied within limits. Because IEEE802.11adopts DCF mechanism, so it can’t provide priority service in whole terminals and all the services stay in equal level. In this paper, we design a channel model based on EDCA mechanism which has competitive priority for WAVE network. In this network system, different nodes requiring different service will change CCH intervals dynamically in regardless of solid channel intervals. This paper designed a different slot allocation algorithm in accordance with network loads conditions, it made different nodes have a successful appointment of SCH, and also can transmit information successfully.First of all, we established a channel model based on EDCA mechanism. The single node appointed CCH intervals and implied a transferring model which providing different priority service. In this model the node collision status probability, transferring status probability of Markov chain model in accordance with channels’ state were calculated.Secondly, we designed the algorithm of control channel CCH intervals. Different priority nodes combat for ordering service channel in control channel. It improves channel utilization rate and makes channel intervals allocate reasonably. All the nodes combated for service channel in control channel transmit successfully in service channel. So we designed a algorithm which allocated intervals dynamically.Finally, this paper analyzed the system performance on the base of algorithm provided above. It compared with the MAC protocol based on DCF mechanism which has no priority difference in throughput and channel access delay.The experimental results show that the performance throughput and channel access delay of the algorithm based on EDCA scheme are obviously improved compared with the algorithm using DCF scheme. And also the throughput in SCH improves above15%when the number of the accessing nodes is verge to a big amount. In channel access delay aspect, the nodes collision rate of the protocol based of DCF mechanism is higher, so its channel access delay is longer. On the contrary, the protocol a lgorithm designed in this paper has a shorter channel access delay, and also has a faster speed to stability.