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
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
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
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
Which are the other countries that are using this
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)
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
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
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
What is frequency clearance?
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.
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
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
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
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
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?
Tell us what you think of this story