Performance Measurement of VoIP Codecs in Different Transmission Models

• Main Authors: Ching An Hsieh, 謝景安
• Other Authors: Chih-Yu Wen
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/08657319640624632137

碩士 === 國立中興大學 === 電機工程學系所 === 97 === Voice Over IP is a hot topic for network technology. It refers to real-time delivery of packet voice across networks using the Internet protocol. Due to the bandwidth is shared by Internet users, the voice packages will compete with the traffic load, which make the voice quality deteriorate rapidly with heavily traffic load. Voice quality is affected by unreliable packet delivery. Therefore, one of the main problems in the implementation of packet voice over IP is to maintain the desired QoS . In this thesis, we discuss some factors of voice quality, including the choice of speech codec, packetization, packet loss, delay, delay variation (jitter) and network service model, Based on these factors, we propose a method to evaluate the communication quality for VoIP networks and to examine the relationship between the jitter and the characteristics of the background traffic. We simulate the VoIP traffic by NIST(National Institute of Standards and Technology) Net and Chariot. Given six speech codecs and two transmission models, regarding the results of our simulations, the performance analysis for the delay and delay jitter of different speech codecs based on two background traffic is presented.