Researchment And Implementation Of Development Sulution And Key Technology Of Voice Communication Of IMS Terminal Based On ARM Embedded System

With the development of next generation network NGN (Next Generation Network) and VOIP (Voice over Internet Protocol)technology matures, people's demand for communication services is not the voice calls only, but the internet application which is the integration of voice, video, information, entertainment and other services. Conform to this trend, telecom operators propose to research an embedded terminal integrated a variety of services.Currently, IMS is considered to the core technology of NGN (Next Generation Network).It is not only a solution to the convergence of mobile and fixed network, but also an important way to integrate the voice, data and video services. Based on SIP (Session Initiation Protocol) system is a key component of multimedia applications implemented in next generation network.This paper firstly summarizes the research focus and key technologies of IMS terminal based on embedded system, and the general design strategy of IMS terminal based on embedded system, including terminal management strategy, the choice of embedded platform, in addition to this, signaling selection, transmission protocol selection and codecs selection of audio and video communication,interface design strategy and other related strategies; Secondly,this paper elaborates the design and implementation of IMS terminal based on embedded system, includes design and implementation of interface, the configuration management of the IMS terminal, telephone, SMS, contacts, call history, multimedia, information browsing, Gallery, Web browsing, push to talk and terminal settings; Thirdly,this paper researches Audio codecs and improves supported audio encoding format of IMS terminals, adds the G.729 audio codec to the open source library of SIP, while this paper researches IMS terminals audio echo cancellation (AEC) function, integrates echo cancellation algorithm with the SIP open source library; Finally, this paper researches packet loss compensation (PLC) mechanism, Voice Activation Detection (VAD), Comfort Noise Generation (CNG), delay and jitter of the IMS terminal, design and implement the RTCP protocol and speech coding based on network adaptive algorithm. Based on the above work, this paper applies the method which is called average subjective value (MOS, mean opinion score) to assess voice quality of IMS terminal. The voice quality of IMS terminal added to audio echo cancellation before and after are compared, and the voice quality of IMS terminal and linphone are compared.Lastly this paper verifies network adaptive algorithm based on RTCP and speech codecs.