Based On The E-model Of Voip Quality Evaluation System

Along with the rapid development of network technology, VoIP started to play its major role during our daily communication. However, the data transmission provided by IP network seems to be unreliable and lowers the VoIP audio quality by loss, delay and jitter. Therefore, research on the evaluation of VoIP audio quality could be considered as a necessity to make improvements.In this article, we propose a VoIP quality evaluation system based on parameters that impairs VoIP communication. Firstly, the development of VoIP and the theory of H. 323 will be introduced. Secondly, H.323 will be selected to analyze and improve the factors that affect the audio quality of VoIP communication. Then, we will circumstantiate the principal as well as applied research of E-Model. We will also design and achieve an E-Model based evaluation system of VoIP quality which uses interfaces of WinPcap to capture Ethernet packets, grabs VoIP audio stream packed by RTP protocol. It computes loss, delay and jitter by unpacking RTP packets, extends E-Model by proposing Ij parameter, simplifies the extended E-Model using default values provided in ITU-T G. 107 which is utilized to calculate corresponding R value and MOS score. Thus, audio quality could be ranked. According to the emulation, we will find out that the MOS score of our system matches the PESQMOS score of ITU-T PESQ system, which approves our system accurate in the evaluation of audio quality.Whereas ITU-T's E-Model doesn't consider the impact of jitter, we will use extend E-Model containing a new parameter Ij based on H(Hurst coefficient) and T(jitter buffer size) in the evaluation system which could effectively quantify the influence cased by jitter.