All the Gs, part 1: Governing the radio spectrum

By on 27 Oct 2021

Category: Tech matters

Tags: , , , ,

Blog home

This series examines the history, governance and radio spectrum technology that led to 4G and 5G today. Check out part 2 and part 3.

Since the invention of modern wireless communication, which pretty much defines the 20th century (Marconi secured his patent in 1896), governance of the airwaves has been an issue.

In times of war, for example, warring parties confiscate radios and wires are cut, forcing the enemy to use radio. Why? So the enemy will have to use communication with a radiating quality that allows others to eavesdrop. It is named ‘radio’ because it goes out into the world like waves on water, radiating outward.

Who could regulate such a thing?

At the time of radio’s emergence, the most natural fit was the body that regulated postal services and telecommunications over wires — the International Telecommunication Union (ITU). The ITU predates the UN by many years, even though it’s now included within UN regulatory processes. 

This formed the backbone of regulation for all services that emerged from radio waves, right up to 5G today.

Why is radio spectrum management so complicated?

Radio spectrum management is tough because of interference. 

The first radio technology used spark gaps to make radio waves. This flooded the radio spectrum from top to bottom with noise, and the signalling unit was a pulse. But the pulse was everywhere, across every frequency, and anywhere within range could receive it. Depending on the strength of the transmission, your signal (in Morse code, also taken from the International Telegraph Code) could be heard by everyone.

There was, of course, a lot of interference from other signals. When mechanisms emerged to select just one section of the radio spectrum, there needed to be governance of this system, or everything would be drowned out with overlapping interference.

Assigning chunks (typically called ‘channels’) of radio wave frequency was needed for different purposes and remain in use until today. Some of these uses are:

  • Military — to source radio communications equipment for their battlefield and strategic communications, worldwide. 
  • Emergency services — for multiple uses in the field.
  • Public radio and television broadcasting — use bandwidth to provide radio and television services.
  • Private communications in microwave radio need assigned frequencies, phase, strength and even direction (microwave is often beam-formed).
  • Some consumer devices (phones, microwave ovens) ‘burn’ radio spectrum inside the home, making it unusable by other devices.

Frequency, strength, and phase

Putting aside who gets what frequency, there are basically only three elements of radio waves to note — frequency (or wavelength), strength (amplitude), and phase. These qualities become the defining characteristic of the radio spectrum’s segment:

  1. What frequency are you in and how wide (how many related frequencies) is the channel?
  2. What strength can you send at?
  3. What encoding (FM or AM, or phase modulation) do you use?

But there’s an important fourth — who decides?

Is this part of the spectrum licensed? There are sections of the radio left bare, leaving the specific region available for astronomy research, for instance. There are also parts left ungoverned, in the sense that anyone can use them without explicit licence. The whole process of deciding who-does-what is what the governance model is about.

What frequency is it?

This asks where in the spectrum of electromagnetic energy the radio signal lies, and is referred to as the ‘channel’. In old school AM and FM radio, the channel is the radio station’s allocated frequency in the radio spectrum. Sometimes, this is called wavelength, and older (pre-digital) radio users often talked about short, medium, and long wave services. Wavelength and frequency are inversely related, so shorter waves are higher frequencies and longer waves are lower frequency.

Take a radio station where I live in Brisbane, Australia, for example. B105FM’s frequency is 105kilohertz. Frequency relates inversely to wavelength (a shorter frequency means longer waves). If the wave gets short enough it can heat things, hence the term ‘microwave’ oven. Get shorter, and you can ‘see’ the waves in the form of light. Get shorter still, and the light sees through you as an x-ray. Go even shorter, and you get gamma radiation. They can all kill you, if they’re strong enough.

Wavelength defines distance and penetration of physical objects, too. Longer waves travel reasonably easily through solids and water, allowing television receivers inside concrete buildings to pick up radio signals from a television station’s antenna over large distances. However, weaker radio waves at higher frequency won’t travel on a rainy day (in some cases) because they bump into the water in the air. 

What strength is it?

By default, radio waves spread in a sphere out from the source, but careful design of the antenna and related materials can direct the radio waves with increased strength in one direction, or even into a ‘waveguide’, like cable television (and even the original Ethernet). With a waveguide the radiation can be directed but can still cause interference or be interfered with. So, this needs to be managed.

Strength, or amplitude, is like how loud a given radio signal is being shouted. Amplitude Modulation (AM) radio changes the peak heights of the waves. The waves lie in a single(ish) frequency, so you tune the radio to a frequency, and then select the signal from the changes in strength.

In Frequency Modulation (FM), a constant strength signal is sent, with variations in the frequency. This means ‘tuning’ must select a range of frequencies that implicitly become the ‘channel width’, therefore assigning a channel to only one thing at a time, to avoid collisions (because waves interfere). With wider channels more data can be sent, but will burn radio spectrum, which is scarce, especially where are specific needs, like getting inside buildings, or not being affected by rain. 

What phase and encoding is it?

Unlike strength and frequency, phase is a strange quality of radio waves and doesn’t factor much in regulation, at first glance. Encoding in phase makes high speed digital communications possible in some circumstances, but again, must be planned for and understood.

The supply chain needs certainty

Aside from the interference and specific use issues that require governance, supply of radio-telecommunications equipment worldwide depends on basic norms.

To make an FM radio in Viet Nam for sale to consumers in Jakarta an important consideration is whether the locally-sourced radio receiver parts will work in Jakarta. When some economies deliberately choose unusual frequencies, or encodings, the reason is usually domestic market control. They may want to limit service access to providers within their own control, limit Intellectual Property Royalty (IPR) payments to outside bodies, or require use of the supply chain inside the domestic economy. For other economies, this decision is the inverse; they have no capacity to make things and depend on the agreement to use standard channels, frequencies, and encodings. It works out better for everyone when these things are simpler.

Of course, you get competing standards. It’s often said that the good thing about standards is there are so many to choose from. In radio there has been competition between different encoding models, different signalling models, designs that preference quality over delay, or delay over quality and ensure rapid delivery, with some loss. It all depends on what you want, where you are and ultimately, who is profiting. With competing standards there’s often a better outcome because there is a standard.

Governance is about certainty

For suppliers, providers, and consumers, the whole point of the ITU radio regulatory process is to deliver the certainty needed, from all viewpoints. When there’s good governance, telecommunications providers can share precious radio space to run emergency communications, public and private mobile telephony, data services, and more. Parts and systems will inter-operate well, and there are viable consumer markets for these services and off-market uses for ordinary people.

The point of all this to lay the groundwork for understanding broadband cellular network technology in use today, which I’ll explore in the next part: All the Gs, part 2: 2G to 4G.

Rate this article

The views expressed by the authors of this blog are their own and do not necessarily reflect the views of APNIC. Please note a Code of Conduct applies to this blog.

Leave a Reply

Your email address will not be published. Required fields are marked *