Research And Implementation Of VoIP In Wireless Mobile Termination

VoIP is the abbreviated form of Voice over Internet Protocol, it means transmitting analog signals of voice on Internet after converting them into digital signals,so it has the characters of low cost and high expansibility. In recent years, more and more companies are trying to develop products based on VoIP,and their research results make VoIP technique relatively mature now. But a coming serious problem is that IP Internet can not promise the (Quality of Service)QoS of real-time communication signals like voice and video,so how to guarantee VoIP QoS become the bottleneck to popularize VoIP application. This thesis is just based on this bottleneck and it provide the relevant solutions.The first part of the thesis describes the current research situation of VoIP at home and abroad and extracts the QoS problems now that we should face to. The middle part describes the theory of VoIP QoS, analyzes the key factors that affect the QoS: voice coding method, jitter buffer technique, echo cancellation, then put forward to relavent proposals: Evaluate the different voice encryption algorithm basing on bandwidth requirement, average viewpoint value, distortion damage value,complexity and other more marks; Introduce the jitter buffer algorithm and praise self-adapting jitter buffer algorithm is the best algorithm currently to resolve the jitter; Discribes echo cancellation and provide the method of echo canceller. The last part introsuces the mobile terminal project, emphasize the relevant methods that should be adopted to guarantee QoS, provide the concrete design process and the main data structure and algorithm; The latter end gives the conclusion of the whole thesis and provides the techniques should be further researched next step.The project that this thesis bases on has been finished and the prouduct has been put into market.