5.150 The following bands:
are also designated for industrial, scientific and medical (ISM) applications. Radiocommunication services operating within these bands must accept harmful interference which may be caused by these applications. ISM equipment operating in these bands is subject to the provisions of No. 15.13.
5.282 In the bands 435-438 MHz, 1 260-1 270 MHz, 2 400-2 450 MHz, 3 400-3 410 MHz (in Regions 2 and 3 only) and 5 650-5 670 MHz, the amateur-satellite service may operate subject to not causing harmful interference to other services operating in accordance with the Table (see No. 5.43). Administrations authorizing such use shall ensure that any harmful interference caused by emissions from a station in the amateur-satellite service is immediately eliminated in accordance with the provisions of No. 25.11. The use of the bands 1 260-1 270 MHz and 5 650-5 670 MHz by the amateur-satellite service is limited to the Earth-to-space direction.
5.384A The frequency bands 1 710-1 885 MHz, 2 300-2 400 MHz and 2 500-2 690 MHz, or portions thereof, are identified for use by administrations wishing to implement International Mobile Telecommunications (IMT) in accordance with Resolution 223 (Rev.WRC 15)*. This identification does not preclude the use of these frequency bands by any application of the services to which they are allocated and does not establish priority in the Radio Regulations. (WRC 15)
5.393 Additional allocation: in Canada, the United States and India, the frequency band 2 310-2 360 MHz is also allocated to the broadcasting-satellite service (sound) and complementary terrestrial sound broadcasting service on a primary basis. Such use is limited to digital audio broadcasting and is subject to the provisions of Resolution 528 (Rev.WRC 19), with the exception of resolves 3 in regard to the limitation on broadcasting-satellite systems in the upper 25 MHz. Complementary terrestrial sound broadcasting stations shall be subject to bilateral coordination with neighbouring countries prior to their bringing into use. (WRC 19)
5.394 In the United States, the use of the band 2 300-2 390 MHz by the aeronautical mobile service for telemetry has priority over other uses by the mobile services. In Canada, the use of the band 2 360-2 400 MHz by the aeronautical mobile service for telemetry has priority over other uses by the mobile services. (WRC 07)
5.395 In France and Turkey, the use of the band 2 310-2 360 MHz by the aeronautical mobile service for telemetry has priority over other uses by the mobile service. (WRC-03)
G122 In the bands 2300-2310 MHz, 2395-2400 MHz, 2400-2417 MHz, and 4940-4990 MHz, Federal operations may be authorized on a non-interference basis to authorized non-Federal operations, and shall not constrain the implementation of any non-Federal operations.

Wiki entries

Amateur Radio (13 cm Band)

Current Use 2300–2450 MHz Amateur radio 13 cm band

The band 2300-2450 MHz is allocated on a secondary basis to amateur radio in all three ITU regions. According to the ITU, this band is used for short-range communications and for experimentation.

By virtue of 5.282, in the band 2400-2450 MHz, the amateur-satellite service may operate subject to not causing harmful interference to other services operating in accordance with the Table.

In the United States, only the sub-bands 2300-2310 and 2390-2450 MHz are allocated to the amateur service. The ARRL has adopted the following band plan:

2300.0-2303.0 High-rate data
2303.0-2303.5 Packet
2303.5-2303.8 TTY packet
2303.9-2303.9 Packet, TTY, CW, EME
2303.9-2304.1 CW, EME
2304.1 Calling frequency
2304.1-2304.2 CW, EME, SSB
2304.2-2304.3 SSB, SSTV, FAX, Packet AM, Amtor
2304.30-2304.32 Propagation beacon network
2304.32-2304.40 General propagation beacons
2304.4-2304.5 SSB, SSTV, ACSSB, FAX, Packet AM, Amtor experimental
2304.5-2304.7 Crossband linear translator input
2304.7-2304.9 Crossband linear translator output
2304.9-2305.0 Experimental beacons
2305.0-2305.2 FM simplex (25 kHz spacing)
2305.20 FM simplex calling frequency
2305.2-2306.0 FM simplex (25 kHz spacing)
2306.0-2309.0 FM Repeaters (25 kHz) input
2309.0-2310.0 Control and auxiliary links
2390.0-2396.0 Fast-scan TV
2396.0-2399.0 High-rate data
2399.0-2399.5 Packet
2399.5-2400.0 Control and auxiliary links
2400.0-2403.0 Satellite
2403.0-2408.0 Satellite high-rate data
2408.0-2410.0 Satellite
2410.0-2413.0 FM repeaters (25 kHz) output
2413.0-2418.0 High-rate data
2418.0-2430.0 Fast-scan TV
2430.0-2433.0 Satellite
2433.0-2438.0 Satellite high-rate data
2438.0-2450.0 WB FM, FSTV, FMTV, SS experimental

Wireless Cameras for Content Capture

Current Use 2360–2420 MHz Content Capture for Sporting and Other Major Events

The 3100-3450 MHz band is heavily used in the U.S. to support wireless cameras and other equipment for temporary use during major news and sporting events. These operations are typically under a short-term experimental license (called a Special Temporary Authority, or STA), which may cover multiple venues over multiple dates. Virtually all major sporting events will use this band for some aspect of their operations. The use of this band is coordinated in advance among the band's incumbents (the Federal government), and all systems at the event that wish to share this band.

Prior to the adoption of the 3.45 GHz Service for IMT in the 3450-3550 MHz band, content capture used 3100-3500 MHz, but now those operations do not use the upper 50 MHz to avoid interference to or from 5G systems.

Frequencies in the 2 GHz range are used for similar purposes, also under STA and prior coordination.

1435-1525 MHz is used for similar purposes, plus wireless microphones.

802.11/WLAN/Wi-Fi/WiGig

Current Use 2400–2495 MHz Wireless LANs

Wireless LANS utilize various channels in the 2.4, 5, and 6 GHz bands (multiple countries), and (in theory) the 3.6 GHz band (U.S. only). For a list of which channels are available in which regions, refer to the Wikipedia article.

Wi-Fi is a trademark permitted for devices that are based upon a published standard of the IEEE 802.11 committee and that have been certified by the Wi-Fi Alliance. Wi-Fi is presently incorporated in about three billion devices. Wireless cash registers were one of the earliest applications of what is now Wi-Fi.

Wi-Fi devices operate on an unlicensed basis, generally meaning they cannot cause interference to licensed services, and must accept any interference caused to them. Wi-Fi shares bands with other unlicensed or ISM devices, such as cordless phones at 2.4 and 5.8 GHz and microwave ovens at 2.4 GHz.

Some of the key patents related to Wi-Fi are credited (in the courts at least) to the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia, which has collected over $400 million in royalties and legal settlements over patent rights.

Google Project Loon

Current Use 2400–2500 MHz Project Loon

Starting in June 2013, Google is experimenting with bringing broadband Internet service to remote areas through the use of high-altitude balloons. The service uses the 2.4 and 5.8 GHz ISM bands for both service and backhaul. Google is first experimenting with the service in New Zealand, and claims that 3G-like speeds are achievable.

More information is available on the Google Project Loon Web site (link below)

Industrial, Scientific, and Medical Devices (ISM, FCC Part 18)

Current Use 2400–2500 MHz ISM (particularly microwave ovens)

Part 18 (section 18.301) of the FCC rules designate certain bands for high-power Industrial, Scientific, and Medical (ISM) devices. These devices generate significant radio energy, but not for telecommunications purposes. Examples includes microwave ovens, industrial heaters, medical diathermy, jewelry cleaners, and RFID tags.

ISM devices may be operated in most frequency bands subject to strict power limits, but are allowed unlimited power in these eleven specially-designated ISM bands.

Radiofrequency Identification (RFID)

Current Use 2400–2500 MHz RFID

An RFID system consists of an interrogator and a transponder, and is used for identification and data capture. RFID systems are used for a very wide range of applications, including:

Highway tolls
Vehicle tracking
Container tracking
Inventory control & theft prevention (often used to prevent shoplifting)
Healthcare (patient & drug tracking)
Passports
ID cards
Building entry
Livestock & pet tracking

and numerous other applications.

RFID tags can be extremely small devices with little or no internal power, which respond to an interrogation by utilizing some of the RF energy imparted by the interrogator; or they can be larger powered units that can be interrogated over larger distances.

The ITU is in the process of attempting to harmonize RFID bands, since RFID systems are used for global commerce. ITU Study Group 1 (Working Party 1B) is drafting a new ITU-R Recommendation on RFID.

ISO/IEC18000 is the principal standard for the RFID air interface.

RFID systems typically operate in ISM and unlicensed bands.

The bands listed below represent the totality of the various bands presently used around the world. The exact bands used in specific countries may vary (and is what the ITU is attempting to harmonize).

Unlicensed bands

Current Use 2400–2483.5 MHz Unlicensed band (commonly used by Wi-Fi)

Although these bands are allocated for ISM use, e.g. microwave ovens and industrial equipment, a major use has been unlicensed (Part 15) systems such as Wi-Fi, Bluetooth, and ZigBee. In the period 1995-2005, most of the cordless phones marketed in the US were in the 902-928 MHz band, but conflicts with the other uses and availability of DECT equipment has greatly decreased sales of 902-928 MHz cordless phones.

The rules for these bands sprung from FCC Docket 81-413 which sought to end an implicit prohibition of spread spectrum/CDMA technology that resulted from a focus on FDMA spectrum uses. This resulted in rules adopted in 1985 that allow unlicensed spread spectrum systems to use these bands for almost any possible application subject to a 1W power limit and a power spectral density limit. Initial applications, however, were limited to frequency hopping and "direct sequence" modulations, the latter being subject to ill-defined spreading and processing gain requirements.

An FCC rulemaking in 2002, in ET Docket No. 99-231, dropped the spreading and processing gain requirements, and permitted any digital modulation that meets the power and power spectral density limits. The immediate effect was to authorize Wi-Fi products under standard IEEE 802.11g. Subsequent Wi-Fi standards, including n and ac, were eligible for certification with no further rule changes.

Bluetooth is authorized under the original 1985 frequency hopping provisions.

The 2400 and 5800 MHz bands are used for Wi-Fi.

A good history is "The Innovation Journey of Wi-Fi: The Road To Global Success" by Wolter Lemstra, Vic Hayes, John Groenewegen; Cambridge University Press, 2010.