COGNITIVE RADIO - a smart communication concept

COGNITIVE RADIO

[Here is an article on Cognitive Radio compiled by my students Shijesh, Sibil, Shyju and John by browsing the internet, books and journals]


The Radio Spectrum – that segment of the electromagnetic continuum comprising the radio-frequency range – accommodates myriad communications devices today.

As the Radio Spectrum gets is gets more and more crowded and available frequencies become scarce the evolution of Cognitive Radio may be able to optimally manage the available spectrum.

The use of radio frequency bands has been regulated in most countries through the process of spectrum allocation in which the use of a particular frequency band is restricted to the license holders of the band. Within this framework, spectrum has often been viewed as a scarce resource in high demand. However, various studies carried out have suggested that most licensed spectrums are often under-utilized with large spectral holes at different places at different times.

Cognitive Radio (CR) systems have been proposed as a possible solution to the spectrum crisis. The idea is to detect times when a specific licensed band is not used at a particular place and use that band for transmission without causing any significant interference to the transmissions of the license holder.

Built on the foundation of the Software Defined Radio (SDR), Cognitive Radios will learn and autonomously perform “cognitive” functions as a form of intelligence that comes from their ability to be defined and upgraded using software.

To examine the concept of cognitive radio consider the example.

Let’s say you walk into an empty café called Spectrum. Since all of the tables are available, you position yourself at the best one and settle down for a meal. [Let’s assume all tables have four seats and you occupy one seat].

A few minutes later, another person comes in and sits on a seat at another vacant table.

Soon, if all the tables are full [but there are a few vacant seats on some tables], a new patron must negotiate with someone already at a table to be allowed to share the table. [Maybe she may request you to let her occupy the vacant chair at your table, and you may agree].

This process of negotiation is the concept behind a technology called Cognitive Radio, a way to share and optimally utilize unused spectrum. Cognitive Radio is sometimes called Smart Radio because it senses its environment and reacts to it.

The present paucity of radio spectrum is primarily due to the cost and performance limits of legacy hardware established during the past century. Traditionally, radios were hardwired to operate at a particular power and frequency, and once a station was assigned a frequency, no other station could use it. Over the years, as engineers built radios in cheaper and smaller packages, it became possible to build intelligence into them, making the idea of sharing frequencies possible.

Engineers are now working to bring flexible operating intelligence to future radios, cell phones and other wireless communications devices. During the coming decade, cognitive radio technology should enable nearly any wireless system to locate and link to any locally available unused radio spectrum to best serve the consumer. Employing adaptive software, these smart devices could reconfigure their communications functions to meet the demands of the transmission network or the user.

Cognitive Radio will intelligently know, by sensing, adapting and learning, what to do based on prior experiential knowledge, by building an internal database that defines how to best operate in different places and at specific times of day.

As Cognitive Radios send and receive signals, they will nimbly leap and bound in and out of free bands as required, avoiding those that are already in use. This lightning-fast channel jumping will permit cognitive radio systems to transmit voice and data streams at reasonable speeds.

This efficient use of existing Radio Frequency resources will alleviate spectrum-availability traffic jams and wireless communications may become far more dependable, convenient and, perhaps, considerably economical than it is today. Indeed, if Cognitive Radio technology progresses as its developers hope the airwaves will never be the same again.

Virtual Reality

VIRTUAL REALITY

A Mulla Nasrudin Story

By

VIKRAM KARVE



Here is one of my favourite Mulla Nasrudin stories.


Mulla Nasrudin bought a beautiful house at a picturesque place far away from civilization high up in the hills.

From time to time he would suddenly pack his bags, leave the city, and go away to his house in the hills, disappearing for days, sometimes for weeks, sometimes for months.

And just as suddenly as he used to disappear, he used to unpredictably return back to the city, suddenly, without any warning or notice.

When asked the reason for his erratic and whimsical behaviour, Nasrudin explained:

“I have kept a caretaker woman up there in the hills to look after my house. She is the ugliest woman - horrible, repulsive, hideous, and nauseating. Just one look at her and one feels like vomiting.

When I go to live there, at first she looks horrible. But slowly, slowly, after a few lonely days, she is not so horrible. Then after some more desolate forlorn days, she doesn’t seem that undesirable. And as more and more time passes in lonesome seclusion, a day comes when I start seeing some beauty in her.

The day I start seeing beauty in that horrid woman I know that it is time to escape from my virtual world in the hills. The day I start getting attracted to the hideous woman means enough is enough – I have lived away from the real world for too long - now even this horrible revolting woman has started looking beautiful. I may even fall in love with this ghastly ugly repugnant woman - that's dangerous.

So I pack up my things and rush back to the city.”



So, my dear friend who is reading this…has the virtual world, the cyber world started looking “beautiful”…?

Maybe it’s time to return to the Real World…!

Good Bye, take care…


VIKRAM KARVE

Copyright © Vikram Karve 2009

Vikram Karve has asserted his right under the Copyright, Designs and Patents Act 1988 to be identified as the author of this work.

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