British Telecom (BT) will change the majority of its broadband network to use multicast routers starting next year. This means that complete IPTV services, using quality of service protocols, could then be launched for the first time on the BT network.
The TV network has always maintained that it did not see the need for upgrading its network with multicast routers, which would have meant replacing its entire broadcast network, because of Freeview, the free-to-air DVB-T broadcast network in the UK, is already strong.
This is the reason why it has no IPTV linear TV service, and instead relies on Internet delivered VoD, which offers mostly movies and re-runs on its BT Vision service. BT Vision has devices that also have DVB-T tuners so they can receive Freeview on the same device.
However, Steve White, head of information systems and technology for IPTV at BT, said that the BT network was being upgraded because it was getting too expensive renting DVB-T multiplex space to broadcast Sky Sports to BT Vision customers. So the company decided to send it multicast, he said.
A multicast network uses a Type D internet addressing system where content is sent from one point in a network to another, and any branch along the way can opt to also access that address, or not. Multicast is the basis of the Internet Group Management Protocol and is the foundation of modern IPTV systems. It saves huge amount of bandwidth, because each TV channel only has to be sent around a fiber network once, not as multiple unicast copies. Most public broadband networks across Western Europe do not have multicast, except where they have been upgraded for IPTV.
In 2010, BT and other UK broadcasters were given the rights for re-broadcasting a number of BSkyB channels, and these were directly added to BT Vision. But White said that sending over the internet without full quality of service protection as an adaptive stream wouldn’t have been good enough, so the BT network rented a TV channel on one of the UK DVB-T multiplexes which broadcasts Freeview.
Now BT sees multicast as a way to get back the millions it costs to rent a channel and instead run the service over its own IPTV network. Such a public multicast service could lead to more channels being launched IPTV style.
That would mean a limitless number of IPTV TV channels could be launched through BT’s network, all of them with a signal ample enough to show on a connected TV screen, identical with broadcast TV quality, up to HD and beyond. Proponents to adaptive streaming may believe this is unnecessary, but the difference in quality and reliability is likely to be noticed.