Research On Improving Quality Of Service In SIPHello Media Stack

With the progress of VoIP technology, the function of standard SIP UA gets more and more variety. As a standard SIP UA under self development, SIPHello as a simple UA which support only Voice Communication and Instant Message, have developed to supporting Presence and Video Communication. In future, SIPHello plan to support more functions such as Video Conference and IPTV. In the mean time, people have more and more requirements on service quality. Common research on QoS include: improvements based on network layer such as Differentiated Services and Integrated Services; improvements based on network transporting such as Overlay and application layer rerouting; and improvements based on application such as jitter buffer algorithm. These methods are all based on a limited bandwidth Internet now, and improve quality of service when the network is congested. But we believe the Next Generation Network (NGN) will have unlimited bandwidth and guaranteed QoS, therefore we need to improve service quality based on NGN. In addition, as bandwidth resource getting more sufficient, the requirement of video communication of SIP UA is more and more important. SIPHello can only support simple video communication functions now, and it can not interwork with other SIP UA, so we need to research on compatibility and improvement on efficience.This paper is based on this background. By improving on media stack of SIPHello, we enhance the quality of serviceof SIPHello. As in audio improvement, we refer to some common VoIP UA, make media stack to support high sample rate to improve voice quality. As in video communication, we research on H.263 and it's transporting protocol, plant a open source codec into SIPHello and make some improvements.Firstly, this paper analyzes and researches some technologies in SIPHello in the round, including signal protocol, transporting protocol and codec. Then we research on some problems existed in SIPHello and propose some approaches to improve those problems. The whole work include three parts: make media stack to support 16KHz sample rate; based on some standards, modify the H.263 codec to support interworking with other SIP UA, and improve on video capture. This paper introduce all the realize procedure, and perform tests on voice quality improvement and video communication interworking.The last part of this paper analyzes this approach and its' results on the test datas, the results show that: the voice quality enhanced significantly and SIPHello can interwork with most of SIP UA.