VideoStream

Written on 9:56 AM by ooe

VideoStream covers a portfolio of wholesale products that offers service providers the ability to connect to their customers over an ATM network. The product offers the service provider the ability to connect many users through BT's ATM network and provide an aggregated delivery from the service provider's premises. The VideoStream product is specifically designed and configured to carry real time video from the service provider to the user's TV via a set top box provided by the service provider.

The user has an ADSL connection to BT's network where traffic is aggregated towards the appropriate service provider using the ATM network. The signalling from the user identifies their ‘on demand’ video request. The service provider then transmits the required content back to the requesting user. It should be noted that the signalling channel is always available, but that the transmission of content to the user is only established over the network ‘on demand’.

The user connects to a set top box (STB) provided by the service provider that interfaces to the VideoStream product through an ATM25 interface. The downstream rate is around 2.5 Mbit/s and the upstream rate is set to 256 kbit/s. The downstream rate is specifically designed to enable the flexible real-time delivery of MPEG1 based video content and services. The aggregate connection to the service provider is available over STM-1, 4 or 16 interfaces.

Unlike the IPStream product, VideoStream is designed to support transport of constant bit rate (CBR) services such as a constant video transmission. Where the user is watching a film, for example, this CBR capacity is required for the duration of the film. This means that the use of contention that was used to optimise capacity requirements in the network cannot be used for this type of service. Instead, a technique of overbooking is used. This means that the total number of users exceeds the number of transmission channels from the service provider over the aggregate connection. As not all users will be using the service at the same time, this capacity management is not a problem and use of the transmission channels is managed by the service provider through requests received from the users on the signalling channel.

As for IPStream, it is up to each competing service provider to decide what content, and facilities they will offer their users. However, typical service providers using VideoStream would have the option to provide movies, music videos, time shifted TV, non-broadcast TV programmes on demand, and video games. The interactive nature of the connection also means that familiar video features including stop, fast forward, pause, etc. are also available as part of the service provider's service definition. Finally, e-commerce services such as home shopping can develop to really take advantage of the broadband nature of the connection through the use of video clips and personalised product information.