Last updated

The Unlicensed National Information Infrastructure (U-NII) [1] [2] radio band is part of the radio frequency spectrum used by IEEE 802.11a devices and by many wireless ISPs. It operates over four ranges:


Effective radiated power (ERP), synonymous with equivalent radiated power, is an IEEE standardized definition of directional radio frequency (RF) power, such as that emitted by a radio transmitter. It is the total power in watts that would have to be radiated by a half-wave dipole antenna to give the same radiation intensity as the actual source at a distant receiver located in the direction of the antenna's strongest beam. ERP measures the combination of the power emitted by the transmitter and the ability of the antenna to direct that power in a given direction. It is equal to the input power to the antenna multiplied by the gain of the antenna. It is used in electronics and telecommunications, particularly in broadcasting to quantify the apparent power of a broadcasting station experienced by listeners in its reception area.

dBm is unit of level used to indicate that a power ratio is expressed in decibels (dB) with reference to one milliwatt (mW). It is used in radio, microwave and fiber-optical communication networks as a convenient measure of absolute power because of its capability to express both very large and very small values in a short form compared to dBW, which is referenced to one watt (1,000 mW).

The industrial, scientific and medical (ISM) radio bands are radio bands reserved internationally for the use of radio frequency (RF) energy for industrial, scientific and medical purposes other than telecommunications. Examples of applications in these bands include radio-frequency process heating, microwave ovens, and medical diathermy machines. The powerful emissions of these devices can create electromagnetic interference and disrupt radio communication using the same frequency, so these devices were limited to certain bands of frequencies. In general, communications equipment operating in these bands must tolerate any interference generated by ISM applications, and users have no regulatory protection from ISM device operation.

BandFreq. RangeBandwidthMax PowerMax EIRP
U-NII Low / U-NII-1 / U-NII Indoor5.150–5.250 GHz100 MHz50 mW200 mW
U-NII Mid / U-NII-2A5.250–5.350 GHz100 MHz250 mW1 W
U-NII-2B5.350–5.470 GHz120 MHz
U-NII Worldwide / U-NII-2C / U-NII-2-Extended / U-NII-2e5.470–5.725 GHz255 MHz250 mW1 W
U-NII Upper / U-NII-35.725-5.850 GHz125 MHz1 W200 mW
DSRC/ITS / U-NII-45.850–5.925 GHz75 MHz

Wireless ISPs generally use 5.725–5.825 GHz.
In the USA licensed amateur radio operators are authorized 5.650–5.925 GHz by Part 97.303 of the FCC rules.

Wireless Internet service provider

A wireless Internet service provider (WISP) is an Internet service provider with a network based on wireless networking. Technology may include commonplace Wi-Fi wireless mesh networking, or proprietary equipment designed to operate over open 900 MHz, 2.4 GHz, 4.9, 5, 24, and 60 GHz bands or licensed frequencies in the UHF band, LMDS, and other bands from 6Ghz to 80Ghz.

U-NII is an FCC regulatory domain for 5 GHz wireless devices. U-NII power limits are defined by the United States CFR Title 47 (Telecommunication), Part 15 - Radio Frequency Devices, Subpart E - Unlicensed National Information Infrastructure Devices, Paragraph 15.407 - General technical requirements. Regulatory use in individual countries may differ.

Federal Communications Commission Independent agency of the U.S. Government

The Federal Communications Commission (FCC) is an independent agency of the United States government created by statute to regulate interstate communications by radio, television, wire, satellite, and cable. The FCC serves the public in the areas of broadband access, fair competition, radio frequency use, media responsibility, public safety, and homeland security.

<i>Code of Federal Regulations</i> law code

The Code of Federal Regulations (CFR) is the codification of the general and permanent rules and regulations published in the Federal Register by the executive departments and agencies of the federal government of the United States. The CFR is divided into 50 titles that represent broad areas subject to federal regulation.

The European HiperLAN standard operates in same frequency band as the U-NII.

HiperLAN is a Wireless LAN standard. It is a European alternative for the IEEE 802.11 standards. It is defined by the European Telecommunications Standards Institute (ETSI). In ETSI the standards are defined by the BRAN project. The HiperLAN standard family has four different versions.

5 GHz (802.11a/h/j/n)

Except where noted, all information taken from Annex J of IEEE 802.11-2007 modified by amendments k, y and n. Because countries set their own regulations regarding specific uses and maximum power levels within these frequency ranges, it is recommended that local authorities are consulted as regulations may change at any time.

In 2007, the FCC began requiring that devices operating in channels 52, 56, 60 and 64 must have Dynamic Frequency Selection (DFS) capabilities. This is to avoid communicating in the same frequency range as some radar. In 2014, the FCC issued new rules [9] for all devices due to interference with government weather radar systems. Fines and equipment seizure were listed as punishment for non-compliance.

Radar object detection system based on radio waves

Radar is a detection system that uses radio waves to determine the range, angle, or velocity of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna and a receiver and processor to determine properties of the object(s). Radio waves from the transmitter reflect off the object and return to the receiver, giving information about the object's location and speed.

United StatesEuropeJapanSingaporeChinaIsraelKoreaTurkeyIndia
40/20 MHz [10] 40/20 MHz40/20 MHz [11] 10 MHz20 MHz20 MHz20 MHz [12] 20 MHz [13] 20 MHz40/20 MHz5/10 MHz [14]
U-NII-2C1005500Yes [15] YesYesNoNoNoNoYesNoYesYes
1045520Yes [15] YesYesNoNoNoNoYesNoYesYes
1085540Yes [15] YesYesNoNoNoNoYesNoYesYes
1125560Yes [15] YesYesNoNoNoNoYesNoYesYes
1165580Yes [15] YesYesNoNoNoNoYesNoYesYes
1205600No [16] YesYesNoNoNoNoYesNoYesYes
1325660Yes [15] YesYesNoNoNoNoNoNoNoYes
1365680Yes [15] YesYesNoNoNoNoNoNoYesYes
1405700Yes [15] YesYesNoNoNoNoNoNoNoYes
U-NII-4 [17] 1695845NoUnknownNoYes
(proposed expansion)

See also

Related Research Articles

IEEE 802.11 set of media access control (MAC) and physical layer (PHY) specifications

IEEE 802.11 is part of the IEEE 802 set of LAN protocols, and specifies the set of media access control (MAC) and physical layer (PHY) protocols for implementing wireless local area network (WLAN) Wi-Fi computer communication in various frequencies, including but not limited to 2.4, 5, and 60 GHz frequency bands.

Ultra high frequency The range 300-3000 MHz of the electromagnetic spectrum

Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter. Radio waves with frequencies above the UHF band fall into the super-high frequency (SHF) or microwave frequency range. Lower frequency signals fall into the VHF or lower bands. UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. They are used for television broadcasting, cell phones, satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, and numerous other applications.

Ultra-wideband is a radio technology that can use a very low energy level for short-range, high-bandwidth communications over a large portion of the radio spectrum. UWB has traditional applications in non-cooperative radar imaging. Most recent applications target sensor data collection, precision locating and tracking applications.

Wireless local loop (WLL), is the use of a wireless communications link as the "last mile / first mile" connection for delivering plain old telephone service (POTS) or Internet access to telecommunications customers. Various types of WLL systems and technologies exist.

The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz). Thus it crosses the conventional boundary between the UHF and SHF bands at 3.0 GHz. The S band is used by airport surveillance radar for air traffic control, weather radar, surface ship radar, and some communications satellites, especially those used by NASA to communicate with the Space Shuttle and the International Space Station. The 10 cm radar short-band ranges roughly from 1.55 to 5.2 GHz. The S band also contains the 2.4–2.483 GHz ISM band, widely used for low power unlicensed microwave devices such as cordless phones, wireless headphones (Bluetooth), wireless networking (WiFi), garage door openers, keyless vehicle locks, baby monitors as well as for medical diathermy machines and microwave ovens. India’s regional satellite navigation network (IRNSS) broadcasts on 2.483778 to 2.500278 GHz.

The V band ("vee-band") is a standard designation by the Institute of Electrical and Electronics Engineers (IEEE) for a band of frequencies in the microwave portion of the electromagnetic spectrum ranging from 40 to 75 gigahertz (GHz). The V band is not heavily used, except for millimeter wave radar research and other kinds of scientific research. It should not be confused with the 600–1000 MHz range of Band V of the UHF frequency range.

Code of Federal Regulations, Title 47, Part 15 is an oft-quoted part of Federal Communications Commission (FCC) rules and regulations regarding unlicensed transmissions. It is a part of Title 47 of the Code of Federal Regulations (CFR), and regulates everything from spurious emissions to unlicensed low-power broadcasting. Nearly every electronics device sold inside the United States radiates unintentional emissions, and must be reviewed to comply with Part 15 before it can be advertised or sold in the US market.

Radio spectrum part of the electromagnetic spectrum from 3 Hz to 3000 GHz (3 THz)

The radio spectrum is the part of the electromagnetic spectrum with frequencies from 30 Hertz to 300 GHz. Electromagnetic waves in this frequency range, called radio waves, are extremely widely used in modern technology, particularly in telecommunication. To prevent interference between different users, the generation and transmission of radio waves is strictly regulated by national laws, coordinated by an international body, the International Telecommunication Union (ITU).

A cognitive radio (CR) is a radio that can be programmed and configured dynamically to use the best wireless channels in its vicinity to avoid user interference and congestion. Such a radio automatically detects available channels in wireless spectrum, then accordingly changes its transmission or reception parameters to allow more concurrent wireless communications in a given spectrum band at one location. This process is a form of dynamic spectrum management.

IEEE 802.11d-2001 is an amendment to the IEEE 802.11 specification that adds support for "additional regulatory domains". This support includes the addition of a country information element to beacons, probe requests, and probe responses. The country information elements simplifies the creation of 802.11 wireless access points and client devices that meet the different regulations enforced in various parts of the world. The amendment has been incorporated into the published IEEE 802.11-2012 standard.

IEEE 802.11h-2003, or just 802.11h, refers to the amendment added to the IEEE 802.11 standard for Spectrum and Transmit Power Management Extensions. It solves problems like interference with satellites and radar using the same 5 GHz frequency band. It was originally designed to address European regulations but is now applicable in many other countries. The standard provides Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) to the 802.11a PHY. It has been integrated into the full IEEE 802.11-2007 standard.

High-speed multimedia radio

High-speed multimedia radio (HSMM) is the implementation of wireless data networks over amateur radio frequencies using commercial off-the-shelf (COTS) hardware such as 802.11 access points. Only licensed amateur radio operators may use amplifiers and specialized antennas to increase the power and coverage of the 802.11 signal.

IEEE 802.11y-2008 is an amendment to the IEEE 802.11-2007 standard that enables data transfer equipment to operate using the 802.11a protocol on a co-primary basis in the 3650 to 3700 MHz band except when near a grandfathered satellite earth station. IEEE 802.11y is only being allowed as a licensed band. It was approved for publication by the IEEE on September 26, 2008.

In telecommunications, white spaces refer to frequencies allocated to a broadcasting service but not used locally.

IEEE 802.11a-1999 or 802.11a was an amendment to the IEEE 802.11 wireless local network specifications that defined requirements for an orthogonal frequency division multiplexing (OFDM) communication system. It was originally designed to support wireless communication in the unlicensed national information infrastructure (U-NII) bands as regulated in the United States by the Code of Federal Regulations, Title 47, Section 15.407.

IEEE 802.11b-1999 or 802.11b, is an amendment to the IEEE 802.11 wireless networking specification that extends throughput up to 11 Mbit/s using the same 2.4GHz band. A related amendment was incorporated into the IEEE 802.11-2007 standard.

There are several uses of the 2.4 GHz band. Interference may occur between devices operating at 2.4 GHz. This article details the different users of the 2.4 GHz band, how they cause interference to other users and how they are prone to interference from other users.

IEEE 802.11af, also referred to as White-Fi and Super Wi-Fi, is a wireless computer networking standard in the 802.11 family, that allows wireless local area network (WLAN) operation in TV white space spectrum in the VHF and UHF bands between 54 and 790 MHz. The standard was approved in February 2014. Cognitive radio technology is used to transmit on unused portions of TV channel band allocations, with the standard taking measures to limit interference for primary users, such as analog TV, digital TV, and wireless microphones.


  1. "15.07.2005, Heise: 5 GHz WLAN to be available all over Europe" www.heise.de Archived 2005-08-07 at the Wayback Machine
  2. ""Cisco: Glossary" www.cisco.com".
  3. 1 2 ""Dynamic Frequency Selection for 5 GHz WLAN in the US and Canada" www.cisco.com".
  4. 1 2 3 4 "FCC 15.407 as of October 1, 2014 - hallikainen.com". www.hallikainen.com.
  5. 1 2 3 "FCC-03-287A1.doc" (PDF).
  6. ""15E, Dynamic Frequency Selection, DFS, DFS Approval" fcc.gov".
  7. ""What's New With Unlicensed National Information Infrastructure (U-NII)"" (PDF).
  8. "Driving Wi-Fi Ahead: the Upper 5 GHz Band". 23 February 2015.
  9. "5 GHz Unlicensed Spectrum (UNII)". 12 December 2015.
  10. FCC 15.407 as of August 8, 2008 – hallikainen.com Archived July 24, 2011, at the Wayback Machine
  11. "802.11-2007 Japan MIC Released the new 5 GHz band (W56)" (PDF). Bureau Veritas — ADT. Archived from the original (PDF) on 2007-07-10. Retrieved 2008-02-23.
  12. Israel: צו הטלגרף האלחוטי (אי תחולת הפקודה) (מס' 2), התשס"ו – 2005 (PDF) (in Hebrew).
  13. Korea Frequency Distribution Table 2008.12.31 (in Korean)
  14. India frequency allocation table
  15. 1 2 3 4 5 6 7 8 "Publication Number: 443999 Rule Parts: 15E". FCC . October 5, 2009. Devices must be professionally installed when operating in the 5470 – 5725 MHz band
  16. "Elimination of interference to Terminal Doppler Weather Radar" (PDF). FCC . July 27, 2010.
  17. ""(see page 9) Sharing the 5.9 GHz Band Between Unlicensed Devices and DSRC"" (PDF).