Interactive DTV framework spread over broadcast and communication networks

Interactive Digital Television (DTV) broadcasting is catching popularity while broadband Internet and wireless communication networks are being made available at lower prices. The former is characterised by a guaranteed quality of delivery but a limited and expensive overall bandwidth, whereas the latter offers, in principle, a much higher backbone bandwidth, but suffers from a bad Quality of Service (QoS). 3G mobile networks lie in between as far as QoS or speed is concerned. In order to be successful, new interactive multimedia programmes will have to target all delivery channels. There is then a need for transmitting these programmes alternatively on multiple media to ensure ubiquity and optimise the data delivery based on content requirement. This paper presents a framework for an interactive DTV system implemented on top of current DTV and Internet technologies, which allows an optimal use of the combined broadcast + Internet path bandwidth. We design a "smart" media server that relies on the content type (data or streaming), the service class and available bandwidth to determine the type of content to be sent over the broadcast or the Internet path. We address also the middleware architecture at the client side as well as the multimedia encoding language issue.