Rearch Of Wireless LAN Access Point Based On IEEE 802.11a/b/g

The performance of the Access Point, the core in the Wireless LAN, will directly affect the bandwidth of the whole WLAN and the quality of applications. So the research on Access Point must be very helpful for the Wireless LAN development.The existing condition of IEEE 802.11 is described in the range of the world, and some solutions of Access Point is compared In the thesis, Then, a Access Point that is based on WT4 WLAN chip has been designed, including software and hardware solution.This thesis analyzed Enhanced Network Driver(END) driver in VxWorks. Referring to the data storage format in Linux, data storage format in END driver is changed. The scheme of data receiving and sending also has been improved according to hardware characteristic. Through researching 802.11 MAC that is very important in the whole system and analyzing the Media Access delay of Distributed Coordination Function(DCF) using Math model, the paper has deducted the relationship between Media Access delay and active nodes in the network. A method of improving the performance of infrastructure network has been brought up based on this relationship. In the improved method, through listening the data sent by these nodes, Access Point statistic the numbers active nodes in the network to calculate the best value of Minimum Value of Contention Window (CW_min). Then it sent the CW_min to all the active nodes. When each node sent data, it can set its CW)(min) dynamically. So, the probability of collision in the network can be decreased.The result of test and simulation showed that the Throughput of infrastructure network can be increased obviously by the improved END driver solution and MAC protocol, and verified the correctness of these improvements.