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Use of radio frequency bands of the electromagnetic spectrum is regulated by governments in most countries, in a Spectrum management process known as frequency allocation or spectrum allocation. Radio propagation does not stop at national boundaries. Giving technical and economic reasons, governments have sought to harmonise the allocation of RF bands and their standardization.
A number standards bodies work on standards for frequency allocation, including:
- International Telecommunication Union (ITU)
- European Conference of Postal and Telecommunications Administrations (CEPT)
- European Telecommunications Standards Institute (ETSI)
- International Special Committee on Radio Interference (Comité international spécial des perturbations radioélectriques - CISPR)
These standards bodies have assigned frequency bands in three types of allocation:
- No one may transmit: frequencies reserved for radio astronomy to avoid interference at radio telescopes
- Anyone may transmit, as long as they respect certain transmission power and other limits: open spectrum bands such as the unlicensed ISM bands and the unlicensed ultra-wideband band, and the somewhat more regulated amateur radio frequency allocations. Often users use a "listen before talk" contention-based protocol.
- Only the licensed user of that band may transmit: the licensing body may give the same frequency to several users as a form of frequency reuse if they cannot interfere because their coverage map areas never overlap.
High-demand sections of the electromagnetic spectrum may sometimes be allocated through auctions.
Every day, users rely on allocation of frequencies for efficient use of such devices as:
- cell phone
- cordless phone
- garage door opener
- car key remote control
- broadcast television and audio
- Standard time broadcast
- vehicle-speed radar, air traffic radar, weather radar
- mobile radio
- Global Positioning System (GPS) navigation
- satellite TV broadcast reception; also backend signal dissemination
- Microwave oven
- RFID devices such as active badges, passports, wireless gasoline token, no-contact credit-cards, and product tags
- toll-road payment vehicle transponders
- Citizen's band radio and Family Radio Service
- Radio control, including Radio-controlled model aircraft and vehicles
- wireless microphones and musical instrument links
Power levels vary widely (from 1 milliwatt in a Bluetooth node to 1 kilowatt in a microwave oven). While the general RF band controls propagation characteristics, who uses what is arbitrary and historical. A particular frequency may require line of sight, or may be attenuated by rain, but whether it carries ambulance or pizza delivery traffic depends on what region it's used in.
Earlier equipment could not process higher frequencies, nor was it compact enough to support certain uses. Over time the exploitable frequencies have increased and semiconductors have shrunk. A tube radio is neither mobile nor reasonably battery powered; GPS works at 1,500 MHz and fits in a pocket. A Bluetooth headset can talk to a mobile phone which is trunked on a microwave link, and at the other end someone is on a cordless phone.
The range of "radio frequencies" is a matter of international convention. The separation of countries into the three formal ITU RF allocation regions is one source of different RF allocation policies in different parts of the world. The definition of the ITU Regions is based largely on longitude. According to ITU Radio Regulations section 5.1: Member States assign licenses to stations; article 5 of the ITU regulations allocates frequencies to services (such as broadcasting and mobile). The ITU divides the world into five administrative regions:
- the Americas,
- Western Europe,
- Eastern Europe and Northern Asia,
- Africa, and
- Asia and Australasia.
The ITU also categorises states into three Radio regulatory Regions:
- Region 1
- Europe, Middle East, Africa, the former Soviet Union, including Siberia; and Mongolia;
- Region 2
- North and South America and Pacific (East of the International Date Line);
- Region 3
- Asia, Australia and the Pacific Rim (West of the International Date Line).
Thus, the RF allocations fundamentally differ between continents. Longitude may traverse continents, for example, the 40°E meridian crosses Europe (Russia), Asia (Middle East) and Africa.
The division between Europe and the other regions is the root of the different RF allocations in the ITU Radio Regulations, and standards around the world. ITU-R Study group 1 details how and why there are three separate Regions.
- Amateur radio frequency allocations
- Broadcast license
- Cellular frequencies
- Radio Resource Management (RRM)
- Spectrum management
- Spectrum reallocation
- Frequency coordinator
- Earth observation satellites transmission frequencies
- Haim, Mazar (August 2008). An Analysis of Regulatory Frameworks for Wireless Communications, Societal Concerns and Risk: The Case of Radio Frequency (RF) Allocation and Licensing (Ph.D. thesis). Middlesex University. Retrieved 2010-09-04.
- ITU Radio Regulations - Volume 1 (Article 5) international table of frequencies by ITU Region
- ; ISBN 92-95003-23-3 from public archives of Abdus Salam International Centre for Theoretical Physiscs
- Australian radiofrequency 2009 Spectrum Wall Chart (PDF 300 kb) (from the Australian Communications and Media Authority) On 1 July 2005, the Australian Broadcasting Authority and the Australian Communications Authority merged to become the Australian Communications and Media Authority (ACMA).
- Radio Frequency (RF) Allocations Table Chart to 30 MHz
- Canadian Table of Frequency Allocations (from Industry Canada)
- UK Frequency Allocation Table 2010 (from Ofcom, pdf format)
- US Frequency Allocation Chart - Covering the range 3 kHz to 300 GHz (from Department of Commerce)
- Galbi, Douglas (2002), Revolutionary Ideas for Radio Regulation," Section IV, Personal Freedom and Licensing.
- UnwantedEmissions.com - On-line query of U.S. allocation table, with additional information.
- Cuadro Nacional de Atribución de Frequencias 2007 (from COFETEL México)
- - Pakistan Table of Frequency Allocations
- India Frequency Allocation Plan 2005
- Japan Frequency Assignment Plan 2008
- Harvey J. Levin: Pioneering the Economics of the Airwaves
- The Invisible Resource: Use and Regulation of the Radio Spectrum
- U.S. spectrum graphic from technology Review, 2010
- India frequency allocation