Modeling and monitoring of VoIP connection

The Real Time Transfer Protocol (RTP), widely used in Voice over IP (VoIP) technologies for audio and video data transmission, is analyzed to design a mathematical model of VoIP connection. The model attempts to meet basic features of VoIP technologies as well as key features of the real link functioning like the frame delays, losses, etc. The proposed approach is based on the finite-state unobservable hidden Markov model. The unobservable state is assumed to be a finite-dimensional Markov process, whereas the observation is assumed to be a non-Markovian multivariate point process that indicates the heterogeneous frames reception. For the proposed model, the hidden link state optimal filtering problem given the packet/losses stream observations is formulated and its solution is provided. Proposed link model validity and filtering algorithm performance are illustrated by processing of captured real video streams delivered via 3G mobile network by Linphone VoIP services.