Design And Implementation Of MAC Layer In 5G Terminal Simulation System

With the rapid development of the Fifth Generation Mobile Communication(5G),the number of users in mobile communication networks continues to surge.The capacity of the base station serving the service is limited.When the number of users exceeds the capacity of the base station,the base station will not work properly due to overload,resulting in a large number of services being lost and causing huge economic losses.In order to better simulate the number and behavior of users,the 5G terminal simulator has great advantages for 5G process testing or large-scale user testing under the same base station.In the development and application of 5G terminal emulators,reasonable MAC(Medium Access Control)design is also crucial.This project relies on the Chongqing Municipality's key industry common key technology innovation major theme special project "Development and Application of 5G Terminal Simulation Equipment",based on the 5G scenario in the Releasel5 protocol,to design and implement the multi-user MAC layer function.The specific research contents of the thesis are as follows:1.Design for the main functions of the MAC layer in the 5G terminal simulation system.The functions of the MAC layer are divided into a random access module,a multiplexing and demultiplexing module,a HARQ(Hybrid Automatic Repeat Request)module,and a scheduling module.In the aspect of MAC layer function design,first,based on the research of state machine,a primitive design method suitable for MAC layer is studied.Then,based on this primitive design method,study the state transition and transition of 5G users.Finally,the interaction interface between the MAC layer and other layers is designed based on the status of each user,which is the basis for communication authentication between layers.?2.A design scheme based on thread pool architecture is proposed for the design of MAC layer functions.This solution mainly encapsulates 8 terminals into tasks,and uses the threads in the thread pool to manage the 8 terminal tasks and execute the MAC layer state machine under each task.In terms of the implementation of the state machine of the MAC layer,the design function is used to discuss the implementation ideas of each module,and finally the realization of the MAC layer function is completed.3.In order to verify the rationality of the design and the feasibility of the implementation,the paper uses hardware Digital Signal Processing(DSP)chip,software CCS and software Ubuntu14.04 to test the MAC layer function.First,debug the MAC layer function code based on the Linux operating system to ensure the correctness of the code.Then,the debugged code is transplanted into the DSP development environment CCS for secondary debugging,and the debugging result is connected to the simulation terminal software of the PC through the serial port and displayed.Finally,the DSP analysis results are packaged using wireshark headers and displayed with pcap files.The main contents of the test are:random access process of MAC layer,multiplexing and demultiplexing process,HARQ process.The test results show that the data output by the DSP can be successfully parsed out,which satisfies the consistency of the protocolIn summary,the paper first studies the principle and logic flow of the MAC layer function,then designs the primitive interaction interface between the MAC layer and each layer,and finally tests each module of the MAC layer function,which is provided by the 5G terminal simulation system support plan.