Mobile Voice Over Ip Communication System Audio Codecs

With the development of network technology and mobile communication, the technology of mobile IP will apply more widely, but the existing mobile IP speech communication don't maturation enough in the routing, handoff and speech quality etc,these problems affect the speech quality of communication directly or indirectly. So how to improve the speech quality of speech communication is a hot topic that many project team studies. The designed mobile IP speech communication system in this paper support the mobility of mobile node in the wireless network environment, and retain the good speech quality during the process of mobility.The main work in this paper includes:1. This paper does a study about the SIP protocol and the standard of iLBC speech codec, and proposes a scheme of implement of mobile IP speech communication system by using the combination of SIP protocol and mobile IP.2. Brings forward a scheme of using iLBC speech codec in the module of speech by analyzing the performance and technical superiority of iLBC.3. Under VC6.0, the paper implements the speech codec based on iLBC by using C++ language.4. In order to meet the request of the real-time environment of mobile IP, optimizes the codec by the way of software.It is used the idea of modularization in the design of whole system, mobile IP speech communication system is divided into module of SIP protocol stack, module of server, module of NAT, module of network communication, module of RTP/RTCP, module of speech, module of application. These modules are independent each other, therefore all modules are designed easily and feasibly.Mobile IP speech communication system that designed in the paper is tested by connection, signaling and speech quality etc in the fix network environment. The result of test shows that the system designed in the paper can implement every function admirably.