| TETRA digital trunking communication system is a professional mobile communication system based on time division multiple access,and is mainly used to command and dispatch in public security,security,fire control,military,transportation,government and other departments.The TETRA digital trunking base station is responsible for radio resource management,and communication connection between fixed network and mobile users,and transmission of signals and user information.When there are multiple base stations in the TETRA digital trunking system,the base station synchronization technology is used for mobile stations to perform cell search and handoff.Therefore,TETRA digital trunking base station synchronization technology is one of the key technologies of TETRA digital trunking system development.On the basis of summarizing the base station synchronization technology of various mobile communication systems at home and abroad,synchronization techniques of various mobile communication systems are firstly analyzed and compared in this paper.According to the composition of TETRA digital trunking system and the working process of base station subsystem,TETRA digital trunking base station synchronization functions are analyzed,and the base station synchronization error suppression method is designed,and the base station synchronization technology and synchronization mode are analyzed and compared,and the best base station synchronization technology and base station synchronization mode are selected.Then,based on OPNET simulation software,the network,process and node model of TETRA digital trunking system are constructed by C language,and the state transition diagram of Mobile Switching Center(MSC),switching equipment and Base Station Controller(BSC)are designed,and the simulation results of synchronization error for each node are given,and the influence of the number of base stations and the distance between base stations on the base station synchronization performance is analyzed,and the base station synchronization scheme is determined.Next,based on the Linux operating system,the master clock synchronization software on the MSC side,the slave clock synchronization software on the BSC side,and different timing mode synchronization software between BTS and BSC are developed by the C language,and the synchronization function between the BSC and the MSC based on the 1588 protocol and the synchronization function between the BTS and BSC based on the 3-mode Timing Synchronization Card are implemented.Finally,based on the Windows operating system,TETRA digital trunking protocol analyzer is used to capture TETRA digital trunking system air interface data,and the base station synchronization function and synchronization precision are tested by Xshell tools and Wireshark tools,and the test results meet the design requirements. |
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