Implementation Of Voice Transfer Device Based On The Application Of Integrated Of Multi-Networks

The research project of this thesis is the sub-projects of the Development Programs of the National Natural Science Foundation of China (No.60472053) and the High Technology Research and Development Program of Jiangsu Province (BG2003004). The main task of this thesis is to develop broadband wireless access equipments based on Bluetooth technology, which can access to networks such as public switched telephone network (PSTN), Internet, cellular network, etc., and put them into production. In this thesis, the voice transfer in wireless personal area network (WPAN) is studied further and the concept of voice over WPAN (VoWPAN) is proposed. Then, the voice transfer over PSTN and IP networks are introduced to discuss the solution of integration between WPAN and other existing networks. Moreover, a voice transfer system in WPAN based on Bluetooth is developed out.Firstly, the significance of the project and the design factors of VoWPAN are discussed. Then, the Bluetooth technologies are introduced in detail, which include system architecture, topology of network, protocol stack, application profile and so on. Moreover, Bluetooth technology is compared with other WPAN technologies. The design schemes of access equipments and audio terminals in PSTN are proposed based on Bluetooth technology. The main float diagram of the whole system is given. In the solution of voice transfer in IP networks based on Bluetooth technology, the development situation of VoIP is presented. The Bluetooth network encapsulation protocol (BNEP) is analyzed to combine the applications between VoIP and Bluetooth and the design of VoIP is described.Finally, a Bluetooth voice communication system is proposed for the WPAN. Including audio gateway and voice terminals, the proposed system can provide point-to-point or point-to-multipoint voice connections between the audio gateway and voice terminals. As to the problem of short work time, the sleep mode is enabled, the length of scan windows is minimized, the length of scan intervals is optimized and all host interfaces are disabled so as to decrease the current consumption of voice terminals. By separating the RF part from the host of audio gateway, the complexity and the cost of antenna design can be reduced and shielding effect can be overcome. Because the system is designed on the basis of universal Bluetooth communication protocols, the ordinary Bluetooth products can be compatible with the system. The testing results show that the distance of system communication can reach over 100 meters. This system has applied in many oil fields for well controlling.