| In recent years, the strong rise of mobile internet has promoted the rapid development of wireless communication technology. Because of its advantage of high bandwidth and low prices, WiFi is becoming the first entry to access to the mobile internet. However, the WiFi access point in traditional WLAN must be connected to the Ethernet by cable links, wireless signal only covers “one-jump” range. WiFi mesh network is a distributed self-organizing wireless mesh network based on WiFi technology. It is composed of several nodes which interconnected to each other by WiFi link according to the mesh topology. Each node can be used as an access pointer for the users, and also a wireless router to forward the data of other nodes. Therefore, WiFi mesh network can turn the wireless hotspot to wireless hot area, and solve the problem that traditional WLAN is difficult to deploy and expand the coverage quickly. WiFi mesh network is the new development direction of WiFi technology.This paper is derived from a cooperation project with the enterprise, which means to develop a prototype AP for the WiFi mesh network. We tried to improve the throughput of network by expanding the MAC layer protocol, the research is focused on multi-channel and congestion control technology. Multi-channel technology can effectively reduce the probability of channel competition conflict in the network, and improve the utilization rate of bandwidth. Congestion control technology helps to alleviate the congestion in the network, and reduce the packet sending delay and loss rate. We implemented the function of data transmission on multi-channel in the mesh data backhaul scenario and congestion control mechanism based on an open source network card driver, and analyzed their practical effect in test. The result shows that the scheme actually helps to improve the backhaul data transmission throughput and alleviate the congestion.This paper is divided into six chapters. In the first chapter, we introduced the background of this subject, basic concept and current development of WiFi Mesh network, research focus of this paper, as well as the content of each chapter. The content of second chapter mainly introduces how to use the technology of multi-channel for data transmission in WiFi Mesh network. Refer to the common channel framework proposed by IEEE802.11 s draft, we designed and implemented a channel switching according to the sequence diagram scheme, the key technology and implementation details of which are also illustrated in this chapter. In the third chapter, we carried on the test and analysis to the performance of data transmission over multi-channel technology. The theme of the fourth chapter is the congestion control. In addition to the original code, we implemented a congestion control mechanism on the basis of flow based data schedule function and speed limitation over the token bucket. Similarly, we tested the actual effect of the congestion control solution in chapter five. The sixth chapter is the last chapter, the content of which summarizes all the work we have done, and points out the deficiencies as well as the direction of we need to work on in the future. |
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