Research And Development Of Interconnection Between TETRA Digital Trunked System And Public Communication Network

TETRA digital trunked system is a kind of special mobile communication system,which is widely used for dispatching of police,traffic and other department.Public communication network is an important infrastructure for the whole society.Because public communication network has a wide coverage and fully developed,TETRA digital truned system has a wealth of dispatching functions;TETRA digital trunked system and public communication network will coexist for long time in communication field.Therefor,the interconnection between TETRA digital trunked system and public communication network has important practical value.First of all,based on summarizing the current situation of various research on interconnection between digital trunked system and public communication network at home and abroad,the structure of interconnection between digital trunked system and public communication network,the function of each module and the mapping relationship between SIP message and TETRA signaling are analyzed,and the signaling procedure of call admission,call drop,call rejected from TETRA digital trunked system to public communication network and from public communication network to TETRA digital trunked system are described in detail.Next,the structure of TETRA-SIP gateway,the interface TS-M between TETRA-SIP gateway and MSC,the interface TS-G between TETRA-SIP gateway and media gateway,the interface TS-S between TETRA-SIP gateway and SIP-PSTN gateway are designed,and the PDU of calling control,channel configure and channel release are described,and the main procedure of TETRA-SIP gateway,the processing procedure of the TETRA module,the SIP module and the media negotiation module are given.And then,based on Linux operating system,main procedure of TETRA-SIP gateway,the TETRA module,the SIP module and the media negotiation module are developed by using oSIP and eXosip protocol stack and C language.Finally,call admission,call drop,call rejected from TETRA digital trunked system to public communication network and from public communication network to TETRA digital trunked system are tested,and the results of the test show that the function of interconnecting TETRA digital trunked system with public communication network is implemented by the TETRA-SIP gateway,and the TETRA-SIP gateway meets the design requirements.