Research And Implementation Of Media Gateway Module Of Digital Trunking Communication System Based On WLAN

The digital trunking system based on WLAN is a kind of private broadband mobile communication system which is mainly used in the commanding and dispatching of hotels, guesthouses, restaurants and other enterprises, and there is a huge market in china. The functions such as voice port and video port’s assignment and recovery, base station channel’s assignment and release, voice encoding format’s conversion, voice packet and video packet’s forwarding and recording are implemented in media gateway module. Therefore, the media gateway module is one of the most important part in the digital trunking system based on WLAN.First of all, the development situation of the media gateway in domestic and foreign mobile communication systems are summarized in this paper, based on analyzing the structure of the digital trunking system based on WLAN, the functions such as voice port and video port’s assignment and recovery, base station channel’s assignment and release, voice encoding format’s conversion, voice package and video packet’s forwarding and recording are described, and the signaling processing procedure of individual call, group call and video call are elaborated in detail, and the structure of the media gateway, the MGW-1 interface between MGW-C control module and mobile switching center MSC, the MGW-2 interface between MGW-C control module and MG business module, the MGW-3 interface between MG business module and base station BS and mobile phone server MS-SERVER, the signaling processing procedure of MGW-C module, MG-ACELP module and MG-G711 module are designed, and the PDU of base station channel’s assignment and release, voice and video port’s assignment and recovery are given. Then, the main program of MGW, the MGW-C control module, the MG-ACELP business module and the MG-G711 business module are developed by using C programming language in the Linux operation system, and the functions such as individual call, group call and video call are implemented. At last, the functions of individual call between user terminals, the individual call between TETRA mobile terminal and user terminal, the group call among user terminals, the group call between TETRA mobile terminal and user terminal and the video call are tested. The testing results show that the functions such as voice port and video port’s assignment and recovery, base station channel’s assignment and release, voice encoding format’s conversion, voice packet and video packet’s forwarding and recording are implemented in media gateway module, the results satisfy the design requirements.