QoS Approach Based On DCF In Wireless Local Area Network

In communication networks many kinds of traffic have stringent end-to-end Quality of Service (QoS) requirements,including delay, bandwidth, packet loss rate etc. With the development of the personal mobile communication system and wide utilization of wireless local area network(WLAN), more and more people began to concern on the problems of providing QoS on the wireless networks. Furthermore, the seamless combination of various wireless communication system using Mobile IP is another promising of future framework of wireless network. In this thesis we study the following aspects. We study the QoS strategy in wireless networks. After understanding the wireless local network based on IEEE 802.11, we point out the problem that occur when a large MSDU(MAC Service Data Unit) is to be sent in the DCF mode in Wireless LAN. When a MSDU is divided into several MPDUs (MAC Protocol Date Unit), the later MPDU will service as a important role. It is necessary to improve the priority of the later MPDU. We use the leap, linear and exponential methods to reduce the minimum contention window () and the distributed inter frame space (DIFS) , so . The result of simulation approve that our approaches can reduce the delay of the transmission of MSDU, improve the performance of the network. In different situation we can choose appropriate parameters to satisfy the user's QoS requirement. With the development of Mobile IP, the QoS according to Mobile has been an important issue. In this paper, we compared with several mobile-detection methods, point out that the schedule that combined with network layer and lower layer will have better performance.