Research And Implementation Of Key Technologies For Real-time Processing And Transmission Of High-throughout Information Streams

The data simulation software,as the core component of the navigation simulation source under the Beidou satellite navigation system project,needs to complete the the real-time simulation of observation and navigation messages for the four navigation systems which are GPS system,Galileo system,GLONASS system,and Beidou system,and transfer to the simulation source hardware to complete the simulation of the navigation information.The simulation process of the data simulation software contains a large amount of satellite information and user trajectory information.The calculation is complicated and the time requirements are extremely strict.The delay of the processing and transmission process of a single navigation system must be controlled within 2ms,so the data processing throughout per unit time is very large.In addition,high-throughout information streams processing and transmission is also an important part of software-based radar and Beidou navigation satellite signal quality assessment software.Therefore,the research and implementation of key technologies for real-time processing and transmission of high-throughput information streams become extremely important.This paper analyzes the data simulation process in the data simulation software in depth,defines and tests the information streams processing and transmission delay,respectively,determines the optimization target,and analyzes the factors affecting its real-time performance.Then,some real-time optimization technologies are proposed for the factors that affect its real-time performance.Through the feasibility analysis,the real-time optimization solution for information streams processing and transmission in the data simulation software is designed.The delay of the information streams processing flow in the data simulation software without optimization has exceeded 2ms,the variance has exceeded 200,000μs~2,and the delay of the information streams transmission flow has also exceeded 300μs.For the acceleration of the processing flow of the information streams,this paper analyzes the reasons for the bottleneck of the current information streams processing delay in detail at first,and then analyzes the optimization of the bottlenecks in the two solutions of thread binding CPU core and kernel real-time preemption patch.The thread binding CPU core cooperates with the CPU isolation ensure that the simulation thread can run only on the bound CPU core without competition from other non-system threads,which reduces the delay of information streams processing and improves the stability of the delay.Installing the kernel real-time preemption patch on Ubuntu 16.04 system improves the system’s hard real-time capability,improves the system’s response speed,reduces the system’s delay,and reduces the jitter of the information streams processing delay.After installing a real-time patch on the Ubuntu 16.04 system and binding the simulation thread to the CPU core,the delay of information streams processing of each navigation system in the data simulation software is reduced to less than 1.7ms,and the variance is also controlled to be less than40,000μs~2.For the real-time optimization of the information stream transmission,this paper analyzes in detail the bottlenecks of using the traditional socket method to send and receive messages,analyzes the optimization of these bottlenecks by the Intel open source data plane development kit DPDK,and then optimizes the information stream transmission by using DPDK.DPDK improves the transmission speed of data packets from the network card to the memory by bypassing the kernel,using mode IO,and active polling.Using Tencent’s DPDK-based,open source network framework F-Stack to make up for the shortcoming that DPDK doesn’t have protocol stack.While possessing DPDK-based message processing capabilities,it also has Free BSD-based upper-layer protocol stack capabilities,and has good API compatibility.For the design of the F-Stack single-process single-thread model,the ability to send and receive messages on logical threads is realized through multiplexing.Finally,the optimization and acceleration of the information stream transmission was completed,the delay was reduced to 210μs,and the variance was reduced to less than 10μs~2,and its real-time performance and stability are greatly improved.After real-time optimization of information streams processing and transmission in the data simulation software,the delays of the four navigation system’s simulation processes of the GPS system,Galileo system,GLONASS system,and Beidou system are all reduced to less than 2ms,which satisfies the real-time performance of the data simulation software.It also provides direction and experience for real-time optimization of software-based radar and Beidou navigation satellite signal quality assessment software.