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June 5, 1997


The Negroponte Switch
What is in the air will go under the ground. And what is underground will go into the air. Like, more and more television will go through cables than over airwaves and more and more telephone will use airwaves instead of copper wires buried along roads. That's the Negroponte switch.

Nicholas Negroponte, visionary-in-chief at the Massachusetts Institute of Technology Media Labs, first defined the switch in his futurology masterpiece
Being Digital. It was a Toffleresque prophecy because even as it was being made the switch was happening. The focus was, and is, on an Internet in the sky.

But years before the prophecy, and the ensuing debates, one scientific soul in southern India was busy burning the midnight tungsten. And all the answers to his quest, strangely pointed to the then undefined 'Negroponte switch'.

Dr Ashok Jhunjhunwala of the Indian Institute of Technology, Madras, had figured out that if telephones had to move from 1 per cent of Indian homes to 15 to 25 per cent, the transition would cost an astronomical sum, way beyond the means of a developing country. The only solution was to get rid of the expensive copper wires which need to be hooked to every home wanting a phone connection. There it was. The problem identified, Dr Jhunjhunwala went ahead to make the breakthrough 'wireless local loop' technology possible. And at less than half the price of similar methods developed elsewhere.

In this interview with Shobha Warrier, Dr Jhunjhunwala talks about the significance of corDECT, the 'wireless local loop' system, and the trials and tribulations of his research team which included Midas Communication Technologies Private Limited, a company floated by his former students:

What exactly is wireless in local loop technology?
You have 10, 20 or 30 telephone exchanges in a city which are linked together and also linked to other exchanges in other cities. Our telephones are connected to the telephone exchange through a pair of copper wires, we call them cables. This is called the local loop.

Most existing telecom networks around the world are based on this wired system. The inherent disadvantages in the wired system are many. They require a physical connection between the local exchange and the subscriber, and it involves long installation time, advance detailed planning, intensive labour costs and an architecture intrusive to the environment.

It also involves a loss of revenue to the telephone department because a majority of the network must be installed before subscriber connections are granted and the cabling to our homes itself costs half the price of every line.

Many times we cannot get a telephone connection simply because a telephone line is not available. Almost 98 to 99 per cent of the faults are cable faults. This part of the telephone system has been like this for nearly a 100 years. So we decided to focus of this part of the network. Also, because in India we want to expand telecommunications rapidly, reduce the cost and make it reliable. One of the ways to achieve this is by making it wireless, either partly for fully.

Wireless in local loop technology is basically replacing wires or copper in the local loop with a wireless system.

How do you connect the telephones to the exchange?
We have our own exchange, a 'compact base station'. From the exchange we take three pairs of wires to the base station which can be mounted either on the rooftop of a building or poles in streets. Each of these base stations transmits on a wireless medium to offices or houses.

At homes or offices, you have a subscriber access unit consisting of either a portable subscriber unit known as a 'handset' or the 'fixed subscriber access' unit known as a 'wallset'. From here you can connect to a regular telephone, fax or a modem. Each of these base stations can serve 150 subscribers.

Some experts have described it as a technological miracle. Does that mean it has not been used anywhere else in the world?
This is the technology of the mid-Nineties. There are a lot of wireless telephone systems like car telephones which have been of existence for 25-30 years. But when we are talking about wireless in local loop, we are talking about something that is quite distinct. Most of the earlier wireless systems are designed to provide communication while you are on the move. The quality aspect was not given enough stress because it was not supposed to be used much. But when you are sitting in your office, you are using the telephone almost all the time. The question is: can the (mobile) telephone handle so much traffic? If you really want to replace your telephone with a wireless in local loop telephone, it must be able to handle traffic.

When in office, you may want to get connected to, for example, the Internet. You need at least 9600 bytes per second or 28.8 kilo bytes per second, expandable to maybe 64 kbps. Today on wired lines I can easily get 9.6 and even go up to 28.8 kbps. So, the wireless that we are talking about is distinct from the kind of wireless communication that has existed for the last 25-30 years.

It is different from cellular technology also. Cellular is a generation just ahead of this but its voice quality is nothing compared to the wired one. Data communication ability also is very minimum in this. It can't really be expanded to 64 kbps. But the wireless in local loop can be used for a long time and can be expanded for data communication to 64 kbps. This is the third generation wireless communication technology. This came into existence in the mid-Nineties and we are not the only country that is using it.

Which are the other countries that are using this technology?
See, all the developed countries already have wired lines. All their offices and homes have wired lines. In India not more than 1 per cent of our homes and offices have wired lines. So, they (the developed countries) are thinking of expanding the wired lines for personal communication.

This cannot happen here. But it is extremely important for countries like India, China, Indonesia and Brazil (to expand the telephone network). This (the wireless local loop) gives us a cheap and more reliable communication system. And there are many companies who are making it.

The uniqueness in our system is that it is very, very cost-effective. Our cost is only a third of the price of the existing wireless in local loop technology.

How could you make it less expensive? I have heard that when DoT opened its doors, BPL had planned to make use of this technology but dropped it due to high costs.
When we are talking about the cost of the system, we are talking about Rs 10,000 per system which includes the front-end of the exchange. We have an advantage over the wired system because the cost of copper wire is going up every year. We could offer it at a low cost because we worked really hard on the architecture. Especially in understanding the Indian kind of requirements. And we did all the development work in India which does not really cost a lot of money. The hardware, software, even the designs for ICs (integrated circuits) were done in India so the investment for development was very low. Today a wireless local loop costs $700 in the West.

But in India, if you want to expand the telephone system from 1 to 15-25 per cent, you have to really reduce the cost. This is not well understood in the West. So, when you import technology from the West, it is expensive. BPL was to buy the technology. But here we look at every single aspect. I must admit we are not still talking about poor people, but about the middle class and the upper middle class who can afford to have a telephone. What we aim at is 200 million telephones. If we can achieve that, I will be very happy.

I have also heard that you are going to start an exchange here at Adyar.
It has already been functioning for the last six months. At the Adyar exchange, I have a trial 1,000-line system. From here we are connected to 15 base stations, one base station is on the rooftop of the Adyar telephone exchange building. We have given away around 100 wallsets, some of the wall sets are about 3-4 kilometres along the line of sight from the base station at Adyar exchange.

My office at IIT has a telephone which is 3.5 kilometres from the exchange. When the base station is mounted on the street, on a pole at about 10 metres' height, it can cover 100-400 metres from there. But from the rooftop it can cover 5 kilometres. This is the normal DECT (digital enhanced cordless telecommunications) system.

We are experimenting it to achieve 10 kilometres in urban areas and 25 kilometres in rural areas. The system for the rural areas will be ready in a few months.

You said that in the rural areas you can cover more area. How is this possible?
Because there are no high-rise buildings there. Line of sight is what is needed. The equipment that we would be using will be the same with only some changes.

Are you planning to use the system in any of the rural areas?
Yes. We have four licensees in India who have already started manufacturing it. They will then be offering it to DoT and other private operators. We are expecting millions of lines to be connected with the help of this system.

How do you see India's future telecommunications system with this technology being deployed?
Today we have only about 11-12 million lines in India. Which is just 1 per cent of the households while in the developed countries we have 60-70 per cent telephone lines. Even a country like China has 10 per cent telephone lines. I see 200-300 million lines in India in the next 10 years with the help of this technology.

It was reported that you have had some problems with the Department of Telecommunications. What were they?
There are problems and controversies. But people who have seen our system work think it is good. Yes, some are not happy…

Does that mean you will have difficulties in implementing…
Nothing is done without difficulties. I think we have to overcome all that. All those who have seen this system functioning are happy. And it is functioning here only because of DoT's support.

So, what we heard is not true.
(Reluctantly) Yes, we haven't got frequency clearance. Now, I expect the DoT to say, okay you can try 50,000 lines all over the country. But they are not coming forward. In fact, I have heard that they are trying to buy outside systems. I am not sure about it. I have just heard. But it is true that we have not been given frequency clearance.

What is frequency clearance?
For the geeks
DECT or 'digital enhanced cordless telecommunications' interface unit (D/U), is the heart of the system and acts as the interface to the existing telecom network (PSTN) on one end and as the base station controller on the other end.

It has fully duplicated switch and controls functions including the 'operation and maintenance centre' (OMC). The PC based OMC undertakes complete administration, detailed billing and maintenance.

Each D/U serves 1,000 subscribers through 20 base stations. To the PSTN it provides up to 6 EI trunks. Singnalling between D/U and PSTN is at present available on R2 MFC.

The 'compact base station' (CBS) is a small weather-proof unit, pole mounted for outdoor applications and wall mounted indoors.

This is connected to the D/U on three normal twisted pairs of wires. Each pair is an N-ISDN (144 kbps, 28+D) link in both directions.

The CBS forms a 'micro-cell' with a range of 100-3,000 metres, depending on the propagation environment. Many base stations may co-exist without any frequency allocation.

The CBS is remotely powered by D/U on the same three pairs of wires. One CBS serves from 30 to 70 subscribers depending on the traffic. The maximum traffic handled by a CBS is 5 enangs at 1 per cent blocking. The base stations can be added without any pre-planning to combat higher traffic requirements.

The 'subscriber access unit' is an intelligent device which continuously looks for access to the strongest base stations among many (if there are more than one) and locks to the CBS on the quietest channel through a unique feature known as 'continuous dynamic channel selection' (CDCS).

This ensures interference-free conversation. Another feature is the 'encryption in the air interface' which promises absolute freedom from eavesdropping.

The handset is of small size and weight and uses 3V electronics. Limited mobility is provided by the hand set with walking speed wherein the subscriber can have access to any base station connected to one D/U. The handset has an alphanumeric display, keypad and the air interface circuit.

The wallset is a wall mounted equipment on the user's premises. The antenna can be mounted directly on the wallset for access to indoor CBS. Alternatively, an external antenna connected by RF cable to a wallset can be used to access an outdoor CBS. The wallset provides a two-wire interface to which a standard telephone, a fax machine or a modem can be connected.

The wallset has a battery backup for 24 hours of operations without power.

When you are transmitting wireless, you are using some frequency spectrum which has to be reserved for the particular system. But it has been given to somebody else. Even for mobile communications, the same thing happened. But DoT gave the spectrum to mobile communications later. Similarly it has to be freed and given to us.

Today people like Bill Gates are talking about a communication system through computers, without telephones. How will the wireless in local loop technology adapt to this kind of communication?
A telephone line which does not have data connectivity is very bad for the country. You need lines with a capacity of 64 kbps. After all, the Internet is going to be extremely important. We have taken care to let our system easily integrated into the Internet.

Have you tried this technology at the IIT?
Of course. We tried it out here for five months before we moved on to the Adyar exchange. For the last 8-10 years we have been trying to develop this technology.

The main complaint outsiders have about India is about its bad telecommunications system. How much can you improve, especially at a time when the technology is developing so rabidly in other countries?
Three things have to be looked into. One is the exchange, second is the local loop and the third is inter-exchange connections.

From one exchange to another we have optical fibres which reduces costs and improves quality.

Exchanges are already reliable with the new digital electronics, which too cut down the costs.

Now it is only the local loop that is problematic and that is where we are trying to improve the situation. With wireless in local loop, the subscriber to exchange link will improve. By December, we plan to come out with 64 kbps connectivity.

Do you think your technology will be used all over India?
I foresee it being used all over the world. This month we are shipping the system to Brazil. Then to China, France and Indonesia.

Is it not pathetic that you could sell your system to other countries but here in India, you could use it only in one exchange with just 1,000 lines?
We have to be patient in India. There are difficulties in India. All kinds of difficulties and we have to overcome that. It will not work by just complaining.

Does it frustrate you?
Sometimes it does. But something inside tells us that we have to keep on trying. I know it is an uphill task but we have to go on working. If we, the most resourceful, well educated and more trained people don't try, who else is going to try and change the country?

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