Research On Multi-MSC Distributed Call Control Technology Of TETRA System

Trunked communication has been the focus of much recent effort, withcommunications technology in progress. TETRA, produced by the EuropeanTelecommunications Standards Institute (ETSI), has been widely used in professional fields,including police, fire, rail transportation, military, rescue and so on. As the better systemcapacity and coverage are required, a TETRA system with a single Mobile SwitchingCenter (MSC) cannot meet the demand of users. Moreover, in professional mobile radioand public safety areas, various departments cooperate frequently, which makes theinterconnection among TETRA systems sharply increasing. So, it is urgent need to developthe TETRA system of multi-MSC.The multi-MSC call control technology has been a hot topic in the study of mobilecommunication. Research on that has been relatively mature in the public mobilecommunication. However, many models and methods cannot be directly used in theTETRA system because of the characteristics of it. So, to realize interconnection amongTETRA systems, it is important to design network architecture, location managementmethods, and signaling processes for the TETRA multi-MSC system.The thesis summarizes the main multi-MSC technology of2G and3G, and analyzesthe IP-based network structure of TETRA systems. On the basis of it, the architecture ofdistributed network structure, distributed data storage and distributed call control isproposed. Moreover, several concepts are proposed, including home of subscriber, home ofgroup, main control MSC, relay MSC and code framework, which realize locationmanagement, user paging, group management, group paging, signaling transfer and mediatransfer. Besides, the important signaling processes are finished, including call set-up, calldisconnect, transmit control, short data and handover. Multicasting is used in media transferamong nodes, and special signaling processes about it are designed.The thesis also offers a software implementation of the multi-MSC system, completesthe functions of individual call and group call. A multi-MSC test environment has been setup and lots of tests about individual call and group call are finished. According to the result,the validity and usability of the design are verified. Finally, the call setup delay of thissystem is analyzed, and the result is less than300ms, which meets the design requirements.