Research And Implementation Of Key Technology Based On VoIP Mobile Terminal

Quality-of-service (QoS) limitation is a major challenge for real-time voice communication over IP networks (VoIP). The technology to improve the QoS of VoIP is beening a hot study field.This paper analyzes the main factors that affect the QoS of VoIP: end-to-end delay, voice codec and delay variation (also known as jitter). This paper also gives the definite solution to the above three problems each. It takes P2P (peer to peer) technology to decrease the end-to-end delay, and give the details on how to use the udp to penetrate the NAT to set up P2P connection in the FreePP Mobile Terminal project. When describe the voice codec, the paper appraise the character and performance of different voice codec through bandwidth requirement, Mean Opinion Score, distortion value and complexity. At last, the paper introduces some popular arithmetic which can absorb the jitter just like static adjustment arithmetic and dynamic adjustment between TalkSpurt. Besides, this paper proposed a new receiver-based playout scheduling scheme arithmetic called voice packet playout based on the time-scale modification technique which performs well on aborbing jitter than the previous arithmetic.By now, the commercial product of FreePP Mobile Terminal has been accepted by market.