Research And Implementation Of Police Digital Trunking Terminal Protocol Stack

Police Digital Trunking system is a police-specific command and dispatch system.It has the characteristics of large area system,wide coverage,low cost,and smooth transition from analog to digital clusters.It uses domestic encryption algorithms,has independent intellectual property rights,and can achieve different interconnection between manufacturers' systems.The police digital trunking terminal protocol stack implements mobility management,call control,short message and packet data,as well as authentication and encryption functions.It is the key technology of the police digital trunking system.Therefore,the research and implementation of the terminal protocol stack is of great significance.This article describes the police digital trunking terminal protocol stack architecture,and analyzes the functions of the physical layer,data link layer,and call control layer,based on the review of the research status of digital trunking systems at home and abroad.The main tasks are as follows:1.Mobility management,call control,short message and packet data and authentication and encryption functional modules for the police digital trunking terminal protocol stack are designed;2.The registration and handover signaling procedures of the mobility management module in the protocol stack of the police digital trunking terminal are proposed.The signaling procedures of the call control module voice single call and group call are proposed,as well as the short message and packet data functional modules.Signaling procedures of functions in authentication and encryption modules such as bidirectional authentication are also proposed;3.The interface functions of the protocol stack are defined,based on the UNIX operating system,in the Cygwin development environment and A6 hardware development platform,using the SMC state machine and C language.The mobility management module,call control module,short message module,packet data module authentication and encryption module are developed.The modules implement the functions such as terminal registration,verification,group attachment,handover,call,short message,packet data,authentication and encryption;4.The functions of mobility management module,call control module,short message and packet data module as well as authentication and encryption module are tested.The testing results show that the developed police digital trunking terminal protocol stack meets the design requirements.