TELECOM Systems have changed immensely and have thereby totally changed the lives of people over the last thirty years. It all started with the digitalization of signals, and the consequent rise of signal processing. Voice and Video Signals were not only transmitted but increasingly processed in digital domain. This change was made possible by the introduction of very large scale integrated circuits (VLSI) and the Moore’s law which would make these ICs carry out more and more processing at lower and lower cost. The processor architecture (closely followed by Digital Signal Processor or DSP architecture) also evolved to suit. On the one hand DSPs made communication system design largely a software effort, making it possible to realise vastly more complex designs. On the other hand, the availability of DSPs closed the gap between theory and practice and theoretical innovations were converted into systems in a matter of months.

In India, the changing face of telecom was recognized in mid-eighties, when CDOT under the leadership of Sam Pitroda, took upon the task of making totally indigenous Digital Telephone Exchanges. This significantly reduced the cost of the switching
element of the Telecom network drastically; from being the dominant cost element in the early eighties, switching became a marginal cost element in the nineties. Similarly the digitalization of the long distance trunk network followed by use of optical fibre in the network made possible a backbone network that was highly reliable and offered huge capacity. The cost to performance of the backbone dropped enormously, and
it too become a marginal cost element. That left the access network. It remained not just the primary cost element, but also a very difficult part of the network to build and maintain. The developed countries had

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Paper No 36-C; Copyright © 2006 by the IETE..

already built the copper based access network to most homes and the innovation in this part was slow till the nineties.

Convergence had already taken place in the backbone network where digitalized voice, digitalized video and data would travel together. Switching elements were increasingly being designed to handle all kinds of traffic. However, the access part of the
network however had very little convergence. ISDN, the first effort at convergence in the access, had largely failed to take off.

India, soon to have a billion people, was still struggling to provide basic telephony. Even in cities, a simple telephone connection involved a long waiting period (as long as eight years in mid-eighties). In 1994, we were still struggling to cross ten million lines with less than a million time being added per year. It was at this point in time that the TeNeT (Telecom and
Computer Network) group at IIT Madras, proposed that India get to 100 million telephones in a decade. The group evangelised these goals and the means to achieve them, on public platforms. Today, a decade later, the dream has become reality, due in part to the TeNeT group’s effort. However, convergence in the access is still lacking, and many of the TeNeT groups current efforts are towards this goal.

The next section introduces some of the main activities of the TeNeT group. Section 3 discusses the wireless last mile solution and the group’s efforts at achieving convergence through this route. Section 4 discusses the wired last mile option and fibre backbone issues, and the last section tackles network management issues and the TeNeT group’s approaches to solve them.