On 802.11n Based Multi-Channel Integration Backhual System

Because the high requirements of bandwidth, transmission reliability, delay and stability the wired-line is usually used in the traditional backhaul. However, for some places where are not convenient to install wireline, the wireless transmission is the only choice. For this purpose, wireless transmission bandwidth, transmission stability and transmission delay are the problems to be overcome.The IEEE 802.11n standard proposed a channel binding technology in which the joint channel bandwidth for the binding of two 20MHz to 40MHz makes the channel transmission rate doubled. The further use and extend of the IEEE 802.11n channel binding technology in the IEEE 802.11ac standard makes it support more channels binding. At present, it is the most commonly used with IEEE 802.11n 40 MHZ bandwidth binding. With the use of the channel binding technology, the channel binding technology on the single network card can improve the channel utilization and transmission bandwidth in a certain extent. Normally, for individual user, the single bandwidth is basically enough. However, it is difficult to meet the requirements of the wireless backhaul link which is very high demand on bandwidth. The wireless backhaul commonly used in the field of very few users. There is still much room for improvement in the spectrum efficiency. Therefore, this paper focuses on multi-card and multi-channel bonding technology, which is used to further improve the wireless backhaul link transmission bandwidth and spectral efficiency.This thesis focuses on Linux Bonding technology, which is commonly used for binding ethernet cards, to bind wireless network cards, so as to achieve the purpose of binding wireless channels to expand the wireless transmission bandwidth. And then, the bandwidth binding used for wireless backhual link is investigated to improve the transmission performance of wireless backhaul. Because of the complex wireless environment, the bandwidth binding is easily influence by external interference. Therefore, to ensure stable and reliable bandwidth binding, it needs to integrate the mechanism of initial channel scan and channel assignment, periodic channel scan and the optimal channel selection, periodic interference detection and channel switching, Linux Bonding load balancing, and multi-channel coordination of sending and receiving, and the final composition of wireless multi-channel integration backhaul system. According to the design scheme of wireless multi-channel integration backhual system, a system test platform is built for testing and demostration. The measurement system uses the IEEE 802.11n wireless standard, supports 40MHz bandwidth binding, and gets the theoretical maximum rate of 300Mbps. Finally, the binding performance of two channels, three channels and four channels are tested, followed by test results analysis and summary.