Design And Implementation Of WLAN Reliable Multicast Transmission And Its Network Management

With the extensive application of wireless local area network (WLAN), wireless LAN video applications businesses, based on the standard of IEEE802.11, gradually increased. Today most videos on the Internet are transmitted by multicast, so video transmitted by multicast based on wireless LAN has become a hot research. However, video transmitted by multicast is based on the UDP protocol, which is not sensitive to packet timeout and loss. In the wired network, we can get good visual effect because of low error rate and high throughput capacity of network. Wireless multicast faces many complex problems.Firstly, WLAN system using wireless radio frequency as the transmission medium, surrounding environment has a great impact on the wireless signal, for example, devices based on802.11b protocol use2.4G band, which is a public frequency, channel faces interference of disturbance sources like microwave oven.Secondly, WLAN multicast users have different data receiving capacities, in order not to affect the low receiving rate of user, we need to limit the data forwarding rate of access point (AP).Therefore, to improve the quality of WLAN multicast service has become a key technology.H3C Technologies Co., Limited (H3C), proposed a simple and effective multicast optimization method:convert multicast data frames into unicast frames in the wireless access point, and then forward the unicast data frames. It can not only ensure the video transmission on the whole is still in the form of multicast, i.e. multicast sources send data to multicast members, but also enables the data to have recovery mechanism, forwarding priority setting, high throughput and other advantages of unicast data frame, greatly improves the reliability of multicast and the quality of multicast services. The author participated in the project design, and completed the following work in this project.The first part, achieve the core function of multicast optimization project--convert multicast data frames to unicast frames and forward data. Convert multicast data frames to unicast data frames in a wireless access point, and then set the priority of data frame, ACK strategy etc. according to the802.11protocols in order to improve the reliability of transmission. The second part, implement the network management function of multicast optimization project. In order to enable users to configure equipment more convenient, the author implemented Web network management function of multicast optimization. The user can access equipment through browsers such as IE and Firefox, and then configure the equipment. Control multicast optimization function of opening and closing, select the configuration parameters and query optimization information through the web page.At present, the results of the work have been applied to a variety of WLAN equipment made by H3C Technologies Co.