Echo Cancellation Of Voip Analysis And Research

VoIP technology is a new application which is use packet-switched network to transmit information of video and audio.With the technology of Internet rapid development,use IP telephony based VoIP technology is marked by the IP in packet network and multimedia network for the business objectives of the integration of the two mainstream technologies.It will be a breakthrough that traditional telecommunication and IP network advantage can be complementation.Currently the application of VoIP has been able to achieve most of the traditional functions of PSTN and made further requests based on the quality of voice calls of VoIP.Compared to the PSTN,the quality of IP voice communication is not satisfactory. There are many factors as the echo is the one of main factor.The echo problem of VoIP communication which uses the echo cancellations for the echo processing can attain certain effect.So this paper decribes the depth research and fouces the analysis and improvement in the adaptive filter algorithm module of echo canceller.In the course of the echo canceller design,we use a hybrid algorithm as the core algorithm to improve the module. Through computer simulation tests,the new improved algorithm compared to the traditional algorithms such as LMS and NLMS have the obvious improved in convergence rate.Compared with RLS algorithm has the obvious simplified in algorithm complexity.Firstly,the paper describes the basic principles and technology construction of VoIP, then based on it propose the importance and necessity of echo cancellation.Secondly,the principle and method of echo are analyzed.At the last,we study the adaptive algorithm in echo cancellation application and provide a hybrid algorithm which can take into account the convergence speed and complexity of the algorithm.Through computer simulation and analyze the result.The new hybrid algorithm can effectively improve and optimize the echo cancellation which current commonly used.It not only achieves the related echo canceller technical requirements but also have the better performance indicators.The paper is divided into six chapters: The chapter 1 describes the development of VoIP and trend of development,the characteristics,advantages and problems of VoIP system.The chapter 2 describes the basic knowledge included basic principle and basic model of VoIP.Compared and analyzed the different protocols of VoIP then analysis the key technology and achievement approach of VoIP.The chapters 3 analyze the principles in echo of VoIP and key processing technology. The relationship between echo and delay and call quality.The chapter 4 do the in-depth analysis to key adaptive algorithm of VoIP system's echo cancellation module and study the LMS,NLMS and RLS algorithm simulation.Analyzed and compared the advantage and disadvantage of different algorithms.The paper proposed a hybrid algorithm.Compared relevant analysis comparison to simulation realization can have the optimization results.The chapters 5 analyze the VoIP system and design an effective echo canceller model and simulation analysis.Compared to it and arrive at a final conclusion.The chapter 6 summaries the main research work and describe the paper in different aspects,infer to the future direction of development.