The packet-based networks performance requirements for real-time facsimile transmission

Abstract

The research presented in this paper focuses on real-time facsimile transmission over packet-based networks. With the migration of PSTNs to Next-Generation Networks (NGNs), where data, voice and video share a common packet-switched network, it is crucial to be able to provide the same services with this new technology without any degradation in Quality of Service or inconvenience to the end-user. Facsimile is a widely used service and therefore a mandatory service that must be implemented in the new environment. Facsimile devices and protocols have been optimized for facsimile communication over the PSTN. However, using packet-based communication for transferring a facsimile document, i.e., fax over IP (FoIP), is not straightforward. Real-time facsimile transmission brings different requirements to packet-based networks, which should be considered when implementing a facsimile service over packet-based networks. However, little effort has been made so far to analyze FoIP performance in a packet-based network. This paper presents an analysis of the different requirements for reliable real-time facsimile transmission over packet-based networks. The metrics, the Facsimile Satisfactory Rate parameter, for an evaluation of the overall FoIP transmission quality was proposed, and the various characteristics of the packet-based network, like network delay and its variation (jitter) and packet loss, with an emphasis on facsimile transmission using the VoIP G.711 codec and the T.38 protocol were investigated in order to determine the margins of the network parameters that enable a successful and reliable real-time facsimile transfer over packet-based networks.