Design And Implementation Of Wireless AP Based On Load Balancing

With the rapid development of intelligent transportation system,the need for Internet access on buses is growing.Buses can access the Internet through WLAN technology using an open Access Point.At the same time,when the number of passengers on the bus a lot,AP load is very heavy,and the network resources can not be reasonably distributed,easy to lead to network low efficiency,or even paralyzed.Therefore,it is an inevitable trend for the development of high performance bus network to meet the diverse needs of passengers.Based on the MT7620 A chip produced by MediaTek,a high performance AP product based on AP master load balancing,is developed with Linux as the operating system.The product will be used in the public transportation system and is committed to solve the problem of a large number of passengers to access conflict,to provide passengers with high quality network services.The main research contents are as follows:1)According to the function and requirements of the AP products,it is proposed to adopt the synchronous dual frequency hardware scheme which supports both 802.11 ac and 802.11 n standard.Completed the design and implementation of the relevant chip selection and the main hardware module.Finally,the performance of the product in the5 G band was tested.The test results show that the average throughput of the 5G band is about 90 Mbps,and the transmission delay is about 40 MS.2)This paper analyses the IEEE802.11 standard MAC layer protocol,and the factors that affect the throughput of the wireless network are studied.It is concluded that the throughput of the wireless network is proportional to the number of backfalls and the number of backoffs and the number of sites.On the basis of the above,the paper summarizes the shortcomings of MAC layer under the Internet access scene demand of bus network,and puts forward AP master load balancing strategy based on flow control and load access control.3)This thesis designs the system software framework,analyzes the measurement index,the collection and the updating strategy of the load information in detail,and on this basis to achieve the flow control module,access control module and the corresponding Web management interface The flow control module is further subdivided into three modules: traffic statistics,traffic identification and classification,and traffic scheduling.Complete the PPP-based LTE function module.