A VoIP QoS guarantee method applying the adaptive committed information rate to downstream service-flows in HFC network

This paper proposes an adaptive committed information rate (A-CIR) allocation algorithm for downstream VoIP service flows in HFC networks. Because the current DOCSIS specifications do not guarantee QoS for downstream VoIP service-flows, an A-CIR allocation algorithm is designed, considering the minimally required rate for a VoIP connection and signaling overhead for VoIP call processing in network congestion. To verify the performance of the proposed algorithm, it is directly tested in an active HFC network and the results are presented based on the ITU-T G107 E-model for VoIP service quality. From the results, the proposed algorithm is shown to reduce the packet loss, jitter, and delay in the HFC network and make stable VoIP service quality even in traffic congestion.