Now that everything is transforming wireless, the need for bandwidth is increasing day by day. Not only are we starting to reach the limit in the amount of usable bandwidth, the problem due to frequency limitations and the mass of people trying to use that spectrum is magnanimous and it deserves attention. Is it fair to ask if the spectrum we have now is enough to support the level of activities carried out these days, considering the fact that everything is going mobile? In fact, there is only one electromagnetic spectrum and relatively lesser set of frequencies available for the applications. That being said, are we running out of frequencies?
We might have noticed that as we use up more frequencies, the chances of us stepping onto another frequency is more. This is common when you share Wi-Fi, and when you receive faster response in a channel, which nobody else uses. It depends on the channel allocation and the number of people who use the same set of frequencies. In order to regulate this, there are communication protocols, which define the required frequency the device needs to operate. GSM (mobile phones) uses 900 MHz/1800 MHz in Asia, Europe and Africa. Wi-Fi works well in 2.4 GHz and 5 GHz. Now this was because, many people have flooded the 2.4 GHz spectrum trying to use it creating a need for a new range of frequency for it to operate upon. As these services begin to evolve, this means one thing- new service, more frequency usage!
The crisis of manageable sort is interference. If your home/office has many networked devices, then apparently your channel gets exhausted. This is because you have a finite channel allocation slots and when the devices outnumber those slots, the throughput of the channel reduces, which is not easily solvable unless fundamental change in the protocol is made. Think of this in a much larger scale covering the whole wide world which includes TV broadcasting, Internet, other forms of communications like phone calls, military applications etc. This is the reason why several organizations are seeking a different frequency spectrum allocation due to the overly increasing bandwidth requirements.
Indeed the amount of spectrum is finite, and new blocks of spectrum are made in small chunks, at a fairly higher price, we absolutely have sufficient spectrum, provided we make better use of it. Both technology and regulatory policy are important here, and fortunately, both are keeping pace with the increasing demand noted above. More spectrum is being made available, and a good amount of this is unlicensed – available for limited-range activities with no licensing cost.
Because of natural fading, any signal is effective over a limited range. We can re-use the given block of spectrum over distance. This is termed as Frequency re-use. MIMO (Multiple Input Multiple Output) uses multiple antennas at the transmitting and receiving end. Now this improves spectral efficiency, link reliability and reduces fading effect. Combine this with limited range usage, like what is applied in WLANs and WWANs, the crisis does not look as bad as it seems.
Cognitive radio is an intelligent radio, which automatically detects channels in wireless spectrum and then changes its transmission or reception accordingly to ease communication in a given band at one location. This is called Dynamic Spectrum Management. This is kind of, like how the air-traffic control systems work.
We might as well, manage the crisis with quite a few upcoming technologies in our arsenal.
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