Invited Speaker

Exact Sojourn Time Distribution in an Online IPTV Recording System

In this work, we study one particular system in Internet-based Television (IPTv), that is the network-based TV recorder. An example for such a service is OnlineTVRecorder (OTR) service available in Germany. The live TV programs are recorded at the OTR Server and registered users can download their previously programmed shows and later view them offline on a PC or handheld device.

Basically, the system consists of a server (or a server farm) and the bandwidth at which a user can download recorded files depends on different system parameters, such as the number of concurrently downloading users or the user's access speed. The file size the user wishes to download and finally, the impatience the user shows are also key parameters when evaluating the system.

In order to obtain the exact sojourn time of a user in the system, we build up a queuing model where the different network conditions and user behaviour are taken into account. Markov assumptions in the modelling process allow us to extend Sericola et al.'s work [2]; a technique that was also used in Masuyama and Takine [1].

This is a joined work with Tobias Hossfeld (University of Wurzburg) and Kenji Leibnitz (Osaka University).

[1] Masuyama, H. and Takine, T.: Sojourn time distribution in a MAP/M/1 processor sharing queue. Operations Research Letters 31(5), 406-412 (2003).

[2] Sericola, B., Guillemin, F. and Boyer, J.: Sojourn times in the M/PH/1 processor sharing queue. Queuing Systems 50(1), 109-130 (2005).