Saturday, January 17, 2009

Project 2 Speech : Mobile Phones - The Early Days

We take many things in our life for granted. One such thing is the mobile phone. It has become a part and parcel of our lives, almost an extension to our hands and ears. And yet we take it for granted! Perhaps if we could learn something about how it evolved we would appreciate it better. So today I am going to talk about the history of mobile phones.

By 1920s, telephones and radios had become popular means of communication. Telephones enabled one-to-one, two-way communication through electric wires. Radio communication was mainly one-to-many, one-way through wireless medium. Both the telephone and the radio were not portable enough to be carried around and could be used only from a fixed location.

But people wanted to listen to their favorite radio programs even when they were on move. This led to car radios and portable transistors. Now they wanted to use telephones also on the move. This was almost impossible using wired communication systems. You can’t just walk or drive around in the city with a telephone and a long wire trailing behind you. So they invented hand-held walkie-talkies that used radio technology. A conventional radio just had a receiver. But a walkie-talkie had both a transmitter and a receiver. This made one-to-one, two-way conversation possible while on move.

But the walkie-talkies could operate only within a range of 1.5 kms. For longer ranges it required a more powerful and hence bulkier transmitter to be carried around. Now this would have been fine for weightlifters but was certainly not for everyone else. Hence they installed these huge transmitters weighing nearly 40 kilograms in cars. This enabled car-to-car communication while on move. A single central radio tower in the city coordinated the communication up to a range of 80 kilometers.

And then someone had a bright idea to connect car phone to land phone calls. This was the first Mobile Telephone system.

However the problem was far from over. Firstly, how do you provide long-range connectivity to people walking around without expecting them to carry bulky mobile transmitters? Secondly, the mobile phone operators were authorized to use just around 400 channels. Therefore only 400 calls were possible at one time. This was certainly not enough for a big city.

Introduction of cellular concept solved both these problems. The city was divided into small cells of about an area of 25 square kilometers each. Instead of a single central tower for the entire city, each cell had its own base station. All the base stations in the city formed a wireless network to relay the calls to longer distances. So the mobile phone transmitters needed to be just powerful enough for its transmission to reach its nearest base station. This reduced the size of mobile phones and made them portable.

Cellular concept enabled reuse of channels. The available channels were allocated to the cells in such a manner that two adjacent cells did not have any channel in common. But non-adjacent cells could reuse the channels without any signal interference. This method enabled much more people to talk simultaneously.

This was the birth of first generation cell phones in early 1980s. Second-generation technologies like TDMA, CDMA increased the capacity of the cell phones to handle thousands of simultaneous calls.

You very well know what today’s cell phones are capable of. The next generation phones will have high quality audio /video content being transferred at high broadband speeds. We will have features like video chatting, mobile TV, high-definition video TV content, Digital Video Broadcasting. There is lot more to look forward to. As Sharukh Khan says in Om Shanti Om, “Picture abhi baaki hai mere dost!(Show is not over yet !)”
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[Date Delivered : December 20, 2008
Objective:

  • Select an appropriate outline which allows listeners to easily follow and understand your speech
  • Make your message clear, with supporting material directly contributing to that message
  • Use appropriate transitions when moving from one idea to another
  • Create a strong opening and conclusion
Time Alloted : Five to Seven minutes]

4 comments:

  1. Looking back on how mobile communication started, it is quite interesting to see how it turned into something this beneficial.

    ReplyDelete
  2. I actually enjoyed reading through this posting.Many thanks.


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  3. Thanks your blog is awesome.
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