Performance modelling of Video-on-Demand systems

Video-on-Demand (VoD) system have become increasingly popular over time. Currently constructed systems offer to their users a vast array of multimedia content spanning movies, video clips, TV programs, etc. that is made available through many video servers. One of the very important parameters at the initial stage of the system design is the blocking probability that follow the instances of unavailability of service resulting from the lack of provision of access to a given content. This parameter can be defined by means of appropriate tools, i.e. analytical models of systems, that enable to determine the level of losses in a system under design in relation to offered access demand and usage. The paper presents a new method for modelling of distributed Video-on-Demand systems. The proposed method is based on Erlang´s Ideal Grading (EIG) with differentiated availability. Until now, Erlang´s ideal gradings have not been used in modelling systems such as VoD.