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September 5, 20122 min read

Congestion in the Radio Frequency Spectrum


congestionIt has long been held by spectrum-regulating authorities and the radio communications industry that the radio frequency portion of the electromagnetic spectrum is a finite resource in danger of running out.

This is not strictly true. In fact, the spectrum does not exist as a physical entity but is simply a method of classifying electromagnetic waves by their wavelength and frequency.  It is not threatened with exhaustion.

Radio waves are produced naturally and by man-made equipment such as radio transmitters and, depending upon their parameters, these waves will occupy a position within the spectrum, known as a frequency or channel.  Man’s ability to generate radio waves has limits, so in this context the spectrum is bounded by those limits. But even within these boundaries, there is more spectrum available than is ever likely to be needed.

However, if we accept the convention that the spectrum is a natural resource rather than a means of classification, we should also understand that it is unique among natural resources because it can be recycled indefinitely without loss. (While some other resources approximate this, even the most efficient recycling process will suffer some loss over time.)  Additionally, and again uniquely, any piece of radio frequency spectrum can be used simultaneously by multiple users, providing there is sufficient geographic separation.  This suggests that the spectrum is a resource with more capacity than is likely to be needed.

While this looks very encouraging, the physics of radio wave propagation dictate that some frequencies will be more desirable than others.  These desirable frequencies are limited to a few parts of the spectrum and as everybody naturally wants to operate in these prime spots, we have the potential for congestion.

The cause for concern then is not exhaustion of the spectrum, but the rapidly growing demand for access to the prime positions within it.  Managing this demand is the challenge spectrum regulators and the radio communications industry face.

From the early days of radio communications, authorities used individual apparatus-licensing as the most common method to manage spectrum access. As radio technology developed, it became possible to reduce interference and allow closer spacing between users.

Over the years, increasingly-stringent conditions imposed upon manufacturers and operators ensured more efficient and interference-free communications. Essentially, radio frequency spectrum utilisation – particularly the prime portions – is now limited only by the technology used to access it and the management processes in place.

This “command and control” system of regulation worked well for basic communications and broadcasting operations in clearly-defined channels and is still widely used. But a growing demand for mass spectrum access, particularly for personal and social applications, along with the market-based approach to regulation currently in favor, render this model uneconomic for many applications.  That leaves spectrum regulators increasingly resorting to selling management rights over technology-neutral blocks of spectrum rather than attempting to manage it themselves.

In all other respects, managing radio frequency spectrum access is no different to managing any other resource; it must balance supply against demand while governed by politics and economics. The challenge for radio communications solution providers like Tait is to provide ever more efficient and more effective communications solutions.


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