QoS-Factor Transmission Control Mechanism for Voice over IP Network based on RTCP-XR Scheme

With the increasing demand for Internet telephony services by using the Voice over IP (VoIP) technology, techniques for QoS-factor monitoring over IP networks are required to manage the speech quality of VoIP services constantly. This paper presents an end-to-end bidirectional transmission control mechanism to manage QoS-factors such as jitter, delay, packet loss rate, etc., based on the RTCP-XR scheme. Also, we propose and modify the standard RTCP-XR scheme defined by IETF to perform better quality monitoring of VoIP service. In order to evaluate the newly proposed RTCP-XR scheme for VoIP services, we measure in real-time the quality degree of the received speech signal while applying our improved packet loss concealment (PLC) algorithms in a G.729A codec using an implemented session initiation protocol (SIP)-based SoftPhone and a 1-port gateway. And then, for the accurate QoS delivering evaluation of the RTCP-XR Scheme we applied calls through the PSTN to SIP gateways, SIP gateways to the PSTN, and SIP gateways to SIP gateways. The experimental results confirm that the applied VoIP service in real environments with the QoS-factor transmission control mechanism achieve a sufficient accuracy for quality monitoring of VoIP services