Design And Implementation Of A Low Delay Distributed WIFI Baseband Remote Transmission Technology

With the rapid development of Wireless communication network,Wi Fi(Wireless Fidelity)is more and more widely used.However,in large enterprises,schools,hospitals and other densely populated scenarios,the most common solution is to use multiple Access points for Wi Fi signal coverage,which results in high cost and is not conducive to network deployment.Therefore,the new AP with baseband and rf separation can improve signal coverage,but there is no low delay transmission scheme between baseband and RF.To solve this problem,the remote transmission technology of distributed Wi Fi is studied,and a distributed low-delay Wi Fi remote transmission scheme is proposed and its feasibility is verified.The main work is as follows:Firstly,the performance index of link transmission is analyzed for 100 m remote scenario,and the scheme design is completed.Analyze the functional requirements and performance requirements of distributed Wi Fi remote transmission,focusing on the analysis of networking requirements,synchronization requirements,performance requirements and other aspects.Through the analysis of transmission delay,it is necessary to switch at a lower level to achieve low delay transmission.According to the thought of L1 level switch of Flex E technology,a low delay transmission link suitable for distributed Wi Fi is designed,and a suitable link construction scheme and delay management scheme are designed.Secondly,the FPGA design and implementation of distributed Wi Fi baseband transmission scheme is completed based on software radio platform.Firstly,the FPGA code writing,VIVADO function simulation and timing simulation of each module of distributed Wi Fi baseband transmission link are carried out,and then the overall simulation of the link is carried out.Then,based on the remote transmission link,the design of delay management is coded by FPGA.Thirdly,in the laboratory environment,the distributed Wi Fi baseband remote transmission scheme is verified experimentally.(1)According to the scheme design,the link establishment test is carried out,and the link establishment can be completed.(2)Test the end-to-end transmission of business data,and the transmitted data is correct.The bit error rate of BBU(Building Baseband Unit)and RRU(Radio Remote Unit)transmitted data is less than 10-12.(3)Through the time synchronization test of the local clock,it is found that the BBU and RRU can complete the time synchronization,and the time synchronization accuracy is less than one clock.(4)For 100 m fiber remote transmission,the unidirectional transmission delay of all ROC(Radio On Chip)in BBU and RRU after time delay alignment is less than 1.5us.The research results of distributed Wi Fi remote transmission scheme in thesis are of reference significance to the scheme design and engineering experiment of distributed Wi Fi design with high rate and low delay.