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January 5, 1998


MTNL orders for 2,000-line WLL system

The Mahanagar Telephone Nigam Limited is placing an order for a 2,000-line system based on an indigenous 'wireless in local loop' technology.

The system, intended for large-scale deployment, addresses the issue of trade-off between the system's capacity and bandwidth, teletraffic concentration and bit-rate to subscribers, according Professor Jhunjhunwala of the Indian Institute of Technology.

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He told the plenary session of the Science Congress in Madras yesterday that a 1,000-line unit developed by his group of former IIT students is already located at a telephone exchange at Adayar in Madras.

The 28 KBPS mounted unit would serve a 10-kilometre radius and the group hopes to develop the 64.4 KBPS unit within six months.

He told reporters that orders have been received for a 100,000-line system from a Brazilian company and the technology has already been transferred to a French company and two Chinese companies.

Another Brazilian company, which had taken the technology from them, is expected to undertake field trials over the next 10 days.

The system has already been validated and efforts are underway to upgrade the technology to make it cheaper per line for very sparse rural deployment and high-speed data services because no frequency planning is required in WLL.

Various modes of the system could also be deployed to serve a wide range of subscriber densities, he added.

Jhunjhunwala said most of the 15 million telephone lines in the country are in the urban areas and the cost estimate of each line is around Rs 30,000.

In the rural areas, the cost is higher around Rs 75,000 per line. The effort should be to bring down the cost per line to around Rs 10,000 over the next five to seven years.

The WLL system, unlike in fibre optics, has the built-in advantage of enhancing the bit-rate connectivity for new services like mobile phones. Internet access could also be provided using the Cor-DECT remote access switch, he added.

With hardly any maintenance cost - as the system is based on radio propagation - the success of the WLL system depends on innovations in deployment so that subscriber densities from as low as 1 per square kilometre to as high as 10,000 per square kilometre are handled equally well.

It is also important that the WLL system interfaces the existing public telephone network in a seamless fashion. He claimed that the wide spectrum of features in services of the Cor-DECT system of their group is ''not available in any single WLL systems today''.

A wall set with an 84 KBPS data interface, as specified in the DECT standards, is being developed which would enable the subscribers to get 64 KBPS access all the way from their home or office at the same cost as a modem link today.

Besides, a wall set with N-ISDN up to 144 KBPS is also under development to provide a s-interface to any off-the-shelf ISDN product.

CCS7 signalling would be supported in the future by DECT interface units when it is configured as an independent exchange.

Earlier: The Lone Ranger - An interview with Professor Jhunjhunwala


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