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HDVSL stands for high definition video capability over subscriber link. HDVSL is an Indian standard built around a network operating system. The standard has been specifically developed to address the need for a high bandwidth low power terminal like a LCD screen. The Technology Development Board of the Government of India conferred the National Technology Day Award on 11 May 2008 on the inventor for developing and commercialising the HDVSL standard - marking the first official recognition of the Indian Government to the new standard for interactive video. The standard uses ITU's G.HN standard for local backhaul inside the premises and then merges with the fibre optic based IP network.


The HDVSL technology stack is very similar to the Chinese 3G standard, but far more spectrum efficient with a scalable path to 10 Gbit/s+ speeds in a wireless terminal. The HDVSL operating system interfaces with terminal level stacks such as android, iOS and Windows. The standard was initially deployed over wired DSL networks in 2007-08. At that point, the network topology consisted of a HDVSL Dslam at the switch end and a HDVSL modem at the home end. The current version 2013 is a significant and quantum improvement over the 2007 version in terms of spectrum efficiency, terminal power requirements and its ability to handle uncompressed video flawlessly.

India has only around 2.5 million DSL subscribers, 80% of which are on the ADSL2+ standard. Indian DSL penetration has been limited by the absence of personal computers in Indian homes. Only an estimated 3 million of the 200 million Indian homes own a computer. Most government plans to increase PC penetration in recent years have failed. Reasons for failure include the cost of a PC, language, computer illiteracy etc. In contrast, India has close to 900 million mobile subscribers, an increasing number of which aspire to own a smartphone. Migrating a DSL+ level of IP data service to a mobile phone is highly challenging.

Some parts of India have population densities in excess of 250,000 people per square kilometer. Coupled with the fact that most of these people live in reinforced cement concrete houses - radio propation and coverage are difficult to overcome challenges. HDVSL is an Indian DSL standard, which successfully addresses this problem. The HDVSL standard operates a 36 Mbit/s duplex Ethernet link - and the HDVSL modem has a direct connection to a display, eliminating the need for a client-side processor altogether. As a result, client side processor based systems such as android, ios and windows can coexist with HDVSL.

HDVSL has an estimated 250K users under deployment in India and China - mostly over an independent RF channel generated from a femtocell interconnected with the internet.The HDVSL standard is likely to see large scale commercialisation as a substitute to LTE in 2013. It is not clear at this stage, how the highly complex semiconductors required for the Multi band RF link would be sourced. Primetel, the inventor of the HDVSL stack is rumoured to have licensed the stack to IBT semiconductors and the first chipsets are expected in Q1/2014 with a 155 Mbit/s duplex ability.

The most ambitious HDVSL deployment on a tier I telco network was the videomail content delivery network (CDN) being built by NYSE listed Mahanagar Telephone Nigam Limited (MTNL) in the city of Mumbai, India. MTNL is the broadband market leader in national capital Delhi and the commercial capital Mumbai with close to one million DSL broadband subscribers. The videomail CDN in Mumbai is believed to have a capacity of over 100 Tbit/s making it probably the most powerful CDN every deployed anywhere. It is believed that this CDN will be interfaced with a global network of femtocells to provide wireless HDVSL connectivity using the unlicensed femtocell bands initially and then migrating to the 90 GHz band.

India has also approved the construction of a HDVSL-compliant rich media data centre with an initial capacity of 28,000 video servers. The data centre is being built by the Interactivity consortium and would connect to the San Francisco to London medianet submarine cable. The Medianet submarine cable is likely to have full function landing points in Singapore Media City and Dubai Media City. Once fully operational - it will facilitate a place shift of television channels making terminal based place shift devices like slingbox obsolete.

Chinese taxis[edit]

China's largest taxi operator will commence trials of a HDVSL based "in cab" television service which plays location specific content and advertisements. As an example, when the taxi is about to approach a famous landmark - a video related to that landmark plays on a 9" screen in the taxi. The HDVSL terminal also provides an audio return path to enable the taxi passenger to access a translation service which can help instruct the taxi driver. A large pilot project was tested during the Canton fair in 2008 with excellent results.


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