The Optimization Of WLAN’s Access Control Mechanism

With the rapid development of the wireless communication systems, wirelesslocal area network (WLAN) is considered as one of the most effective wireless accessmethods. It can expand Internet service to mobile environment successfully, and it hasbeen interpreted as an integral part of future communication systems. As a result, theconnection between Internet and computer, as well as the interrelationship of softwareengineering disciplines, is becoming increasingly close. The access controlmechanism which mainly solves the limited channel resources for the multi-userdistribution, is an important part of IEEE802.11protocol. Whether finite channelresources can be used efficiently in the access control mechanism or not woulddetermine the performance of WLAN.WLAN is introduced, including its standards, development history and accesscontrol mechanism. The software lifecycle, the processes and stages of softwaredesigning and the concept and various methods of software testing are illustrated aswell. Markov chain model is quoted to study DCF access scheme and analyze theperformance of DCF. In P-probability access control mechanism, the networkcongestion information is applied into basic access control, which assigns thecontention window after sending data frames. So the probability of frame collisionmay fall and the throughput of whole network can be enhanced. The mechanism issimple, distributed and adaptive characteristics.OPNET is used to simulate the new mechanism, which is tested by using thetechniques and methods of software engineering. Ultimately the simulation is testifiedcorrect and comes to a conclusion. The experimental result shows that P-probabilityaccess control mechanism can offer a higher throughput while decreasing frame delayand packet loss comparing with the original standard, EIED, MILD.