Radio Spectrum Allocation - Who gets some, and what can they do with it?
Spectrum allocations are a fascinating area, in which the science of radio propagation and the engineering of telecommunications systems are linked with the economics of resource allocation, government regulation and international relations.
The Radio Spectrum is a small portion of the electromagnetic spectrum, generally considered to be between 3KHz and 300GHz. Above this range, we draw close to the visible light spectrum (via infrared), and below it, we're into the Extremely Low Frequency (ELF) range that is too low to be generally useful. Inside the Radio Spectrum lie all the radiocommunications services that contribute so much to modern life. The obvious things like terrestrial and satellite television and radio, mobile telephones, cordless telephones, wireless LAN, GPS, RFID and an alphabet soup of other systems.
The Radio Spectrum is a large but finite resource. It's obvious that if a TV signal is broadcast at a particular frequency, it effectively prevents any other use of that frequency and others nearby. The frequencies are not equal either- some are highly sought after. In general, the higher the frequency, the more data can be communicated. But the atmosphere does not provide a uniform level playing field for all frequencies. At 2.4GHz, water molecules in the atmosphere absorb the signal, so it's difficult to cover long distances without high-powered equipment. At 60GHz, oxygen atoms produce a similar, but much stronger effect. Shortwave radio signals can bounce of the inside of the ionosphere and hence travel around the world. The fundamental physical properties of silicon make it difficult to build equipment to use higher frequencies.
How then to decide what use is made of the spectrum? Who gets to use what frequencies, and what can they use them for?
The traditional response from government has been to determine the best uses for each part of the radio spectrum. The UHF range was adjudged perfect for television broadcast, and so the mid-hundreds of MHz were handed over to certain broadcasters. VHF, a lower range, was selected for FM radio broadcasts. These allocations were made in the days of state-run broadcasters and telecommunications companies. A panel of experts determined what was best, and everyone got on with it. Transmitters, user equipment, and distribution systems were constructed over the decades.
An international body, the International Telecommunication Union (ITU) began to standardise the allocations internationally. This meant that walkie-talkies in one country did not operate all over the radio broadcasts of their neighbours. It also meant that there was an international market for standardised radiocommunications equipment. Local regulators like the FCC in the USA, and Radiocommunications Agency in the UK worked within the ITU guidelines to allocate frequencies to the right services and the right organisations.
As the telecommunications and broadcasting markets became more competitive, the regulators looked for a more market-orientated way to do things. The march of technology was creating faster and faster transistors that could operate at higher and higher frequencies; and the public demand for more and better broadcast and telecommunications services was tangible.
A famous example is the notorious 3G mobile phone spectrum auction in the UK which concluded in April 2000. On offer were five packages of spectrum in the 2.1GHz range. Any organisation could bid for exclusive use of one of the packages for the next 20 years. The old GSM/2G market had four operators, so five 3G packages were created to guarantee at least one new market entrant. The five winners bid between 4 and 6 billion pounds each- a net windfall of 22 billion quid for Her Majesty's Treasury¹. In Germany, a similar exercise netted some €51 billion from six "winners" a few months later.
In these auctions, the governments selected the service (mobile telephony), the technology (3G UMTS) and the best frequencies, but left the choice of operators to the market. They were considered to be a great success at the time. The year 2000 was the peak of the dot com boom, and everyone got over-excited and bid more than they really should. Their self-imposed high payments have undoubtedly slowed down the introduction of 3G services.
Spectrum auctions continue. However, the current generation of auctions do not specify what use the spectrum can be put to- they are said to be "Technology-neutral". Ofcom (the successor to the old Radiocommunications Agency) is currently planning auctions in the 2.0GHz, 2.2GHz, 2.5-2.7GHz, 10GHz, 28GHz, 32GHz, and 40GHz bands. In each of these, ITU obligations will impose some limits on their use, mainly to prevent problems in neighbouring countries. But Ofcom is not laying down any extra rules. The 2.5GHz auction could see a mobile television tycoon bidding against a wireless internet provider for the same frequencies. Eventually, parts of the UHF spectrum (currently used for analogue television) will be auctioned off- will they be won by a mobile phone company or a television broadcaster? Only time will tell.
Future of spectrum allocation?
The next innovation will probably be widespread Spectrum Trading - the idea that organisations with a license to use portions of the radio spectrum will be permitted to sell them directly. This is already legal in many jurisdictions, although large-scale trading has yet to take place.
As technology continues to develop and complex modulation techniques become easier and easier to implement, some argue that the day will soon arrive when many communications systems can share the same frequencies. These free market theorists conclude that the most efficient way to determine how the spectrum is used is to cease regulating it altogether. They hold up the example of the so-called ISM bands at 2.4GHz and 5.1GHz. These are lightly regulated, but anyone can use any type of equipment provided it does not have a very high-powered signal. No license is required; no auctions are held, no exclusive allocations are made. This freedom has resulted in the plethora of efficient and popular WiFi Wireless LAN devices that would probably never have arisen in highly regulated bands.
¹ - Some £600 per head of population! A table contrasts this with other countries' auction results. http://www.3gnewsroom.com/country/index.shtml
- electromagnetic spectrum
- Mike Wills Propagation Tutorial, http://www.mike-willis.com/Tutorial/gases.htm
- The German 3G Licence Auction, http://www.nek.lu.se/NEKRRA/germanauction.pdf
- Byers Announces 3G Mobile Licence Winners, http://www.ofcom.org.uk/static/archive/spectrumauctions/auction/auction_index.htm
- Award of available spectrum: 1452 - 1492 MHz, http://www.ofcom.org.uk/consult/condocs/1452-1492/summary/
- Ofcom Spectrum Awards, http://www.ofcom.org.uk/radiocomms/spectrumawards/