Design And Implementation Of Multi-mode Wireless Networks Based On Wi-Fi

Wireless communication technology and Internet has a rapid improve now, as well as the widespread popularization of intelligent terminals, user demand on the quality of network service becomes higher and higher. Thus, the traditional single-mode WiFi network cannot meet users requirements of coverage, resource utilization, quality of service and so on. Multi-mode wireless transmission technology can combine the different bands of WiFi networking technology with each other very well, achieve mutual benefit and complementarity, and effectively relieve the strain on spectrum. It provides users with intelligent wireless communication system with high stability, low latency, better coverage and better user experience.First of all, in this thesis, the existing multi-mode wireless technologies are described. The switch technology and access to select technology of heterogeneous wireless network are analyzed. The shortcomings of the existing multi-mode wireless technology are pointes out according to the actual situations.Then, this thesis shows the design of multi-mode wireless transmission scheme, which includes system architecture design, protocol stack design, data processing design and data packet frame format design etc. Five kinds of technical routes are proposed for customers' demands and objectives. Firstly, the seamlessly switch of different frequency WiFi network can be completed via the IP tunneling technology. Secondly, the link quality can be real time detected by adopting intelligent wireless link detection technology. The optimal link is selected according to multi-attribute decision algorithm combined with link detection technology. Thirdly, ARQ retransmission mechanism can be used to ensure that IP packets according to the sequence of submission, to solve packet loss and disorder problems caused by link switch. Using multilink redundancy transmission technology can also complete the data transmission on low quality link. Lastly, TCP acknowledgment packet redundant transmission and TCP shunt technology can be used to optimize TCP operation and reduce link congestion. The important modules' implementations of convergent server and the terminals are described in detail.Finally, the system was tested. The result shows that the system can make the terminal seamlessly switching between different frequency WiFi networks. The link quality detection result is good that the system can still provide high quality services in poor network environment. The proposed multilink redundancy transmission technology and TCP acknowledgment packet redundancy transmission technology can improve system performance.