Research And Implementation Of Call Control For Digital Trunked Mobile Station In The Direct Mode Operation

Digital trunked system is a kind of private mobile communication system that synthesizes trunked technology, packet data service, command and control function based on digital communication technology, and it has been widely used in many industries and department, such as public security, security, airport, port and city railway transportation and so on. Because mobile stations mainly rely on the foreign equipment manufacturers, their price is high, and they exists unsafe factor. Therefore, it is significant to develop digital trunked mobile station.The direct mo.de operation of digital trunked is the operation of direct inter-communication between mobile stations without using network infrastructures, it can provide users with voice data, circuit data and short message data service, and its the call control is key to ensure the direct mode operation to work normally.First of all, the features of digital trunked mobile station and development situation of call control for digital trunked in the direct mode operation at home and abroad are summarized in this paper., based on analysing protocol stack of call control for digital trunked in the direct mode operation, the service process of call setting up, call reservation and call release is described in detail. Then, environment functions between protocol stack of call control and user’s interface, interface primitives of protocol stack for call control and PDU of DMCC are designed. And UML language and C language mixed programming is used, the module division of protocol stack for call control in the direct mode operation are implementated by design of class diagram, the interfaces between each module and up-down layer are implementated by design of structure chart, the dynamic behavior of PC and CC function module is implementated by design of state diagram,. Next, the funcations are implementated by using Telelogic Tau, such as call setting up by calling user, call setting up by called user, request transmitting after transmitting cease, receiving call request after transmitting cease, sending call release request, receiving call release indication and so on. At last, the protocol conformance test of call setting up by calling user, call setting up by called user, request transmitting after transmitting cease receiving call request after transmitting cease, sending call release request and receiving call release indication is completed, and based on VxWorks operating system, the funcation tests of call control for mobile station in the direct mode operation, such as call setting up, call transfer and call release are done, the test result satisfies the design requirement.