Wimax plus IPTV: you decide what to watch and when
New Delhi: Television signals carried on an emerging high-speed wireless data network and delivered to your television through a set-top box could be the latest challenge to India’s widespread cable and fast-growing satellite television companies. And the differentiator could well be the killer application that combines both the services: interactive television.
Bharti Airtel Ltd and Reliance Communications Ltd, the country’s top two wireless telecom service companies, are conducting trials of video-based services on Wimax, which is a standard capable of data speeds of 10 megabits per second (mbps, a measure of speed) up to 2km away from a radio transmitter.
State-owned Bharat Sanchar Nigam Ltd has included video capabilities in a tender for vendors competing for its Wimax roll-out mandate.
Currently, digital video streams for television, compressed using standards such as the so-called MPEG-2 and MPEG-4 are delivered to customers’ television sets via direct-to-home (DTH) satellite and cable, but not through radio networks such as cellular, due to the high amount of bandwidth required for such services.
Streaming such services over a local network, such as cable and a cellular or Wimax networks makes it possible to deliver programmes on-demand to each subscriber, unlike satellite-based services where users have to wait for the programme to appear. Subscribers of such services will be able to select their own shows from a list, or a menu, and use playback settings such as pause and rewind, as if they are playing a CD or DVD at home.
“If you are asking me if I can stream a full MPEG-4 video on a Wimax network at 2,500kbps, I don’t know," said Sriram T.V., vice-president for technology at Bharti Airtel, which is exploring the possibility of Internet-delivered TV content or Internet protocol TV (IPTV) over wireless networks such as Wimax using a set-top box. “But we are conducting trials for delivering video streams at 384kbps after compression." A kilobit or kb is one-thousandth of megabit.
The high bandwidth used by video services has been the main impediment to the launch of such services until now. While a normal GSM conversation takes up a bandwidth of 22.8kbps, a typical digital video broadcast stream, such as those used by satellite operators, takes up between 2mbps and 4mbps. Compared to this, the total bandwidth of a typical 3G base-station (using 24MHz spectrum) is only around 12mbps, making it impossible to support more than six subscribers at a time.
But with the emergence of powerful compression techniques and more efficient access technologies such as Wimax, the number of subscribers that can be supported under one base-station or tower has increased to more than a hundred. The government is also likely to allocate 20MHz of spectrum per operator, more than double the current cellular allocations, for the deployment of Wimax and similar services over next few months.
The biggest leap, so far, has come in compression technology, where new software now converts the same video file into one-fifth to one-tenth of what was possible earlier. Though the technology is now used to compress video for the small screen of mobiles, it can also be implemented for bigger screens such as TV.
In addition to lowering the size of the file through compression, another development that has taken place has been the emergence of higher efficiency transmission technologies such as Wimax.
Wimax can carry between two and five times the amount of data carried by a 3G network, depending on configurations. “With 20MHz spectrum, we can deliver more than 50mbps per base station," said Mallikarjun Rao, director for wireless business at Nortel Networks’ India unit, claiming a throughput of three-four times that of 3G networks.
A 50mbps capacity translates into the ability to support around 200 simultaneous video streams at 256kbps each, using one tower and 130 simultaneous users at 384kbps.
Not only can a cellular-based Wimax network be rolled out faster compared with a copper-based one, interactive TV on such wireless technologies will give it an edge over satellite-based services such as DTH.
Besides, the same set-top box can provide access to high-speed Internet, both on the computer and the TV. In fact, interactive content services may begin as an add-on service to a high-speed wireless Internet access service, according to industry insiders, and the combination may be priced around Rs1,000 or more a month.
Broadcast industry veterans, however, point out that commercial arrangements, and not technology-related issues, will remain a stumbling block. “Today, even over cable we can give facilities such as video and content on demand," said Ashok Mansukhani, executive vice-president of Hinduja TMT, one of the largest cable operators in India. “But if the broadcasters will not let you store their programmes, how will it roll out?"
Analysts believe that such issues are likely to be resolved with the entry of big end-to-end players. “The biggest fear of content firms, right now, when it comes to archiving of their programmes, is piracy and proper revenue-sharing," said Timmy Kandhari, executive director for media with audit firm PricewaterhouseCoopers.
“If the programmes are allowed to be archived, then it is also essential that the operator, whether it is the cable-industry or the telecom operator, shares the correct figures about the number of people who watch it and gives the right share of revenue to them."
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