5.149 In making assignments to stations of other services to which the bands:
13 360-13 410 kHz,
25 550-25 670 kHz,
37.5-38.25 MHz,
73-74.6 MHz in Regions 1 and 3,
150.05-153 MHz in Region 1,
322-328.6 MHz,
406.1-410 MHz,
608-614 MHz in Regions 1 and 3,
1 330-1 400 MHz,
1 610.6-1 613.8 MHz,
1 660-1 670 MHz,
1 718.8-1 722.2 MHz,
2 655-2 690 MHz,
3 260-3 267 MHz,
3 332-3 339 MHz,
3 345.8-3 352.5 MHz,
4 825-4 835 MHz, 4 950-4 990 MHz,
4 990-5 000 MHz,
6 650-6 675.2 MHz,
10.6-10.68 GHz,
14.47-14.5 GHz,
22.01-22.21 GHz,
22.21-22.5 GHz,
22.81-22.86 GHz,
23.07-23.12 GHz,
31.2-31.3 GHz,
31.5-31.8 GHz in Regions 1 and 3,
36.43-36.5 GHz,
42.5-43.5 GHz,
48.94-49.04 GHz,
76-86 GHz,
92-94 GHz,
94.1-100 GHz, 102-109.5 GHz,
111.8-114.25 GHz,
128.33-128.59 GHz,
129.23-129.49 GHz,
130-134 GHz,
136-148.5 GHz,
151.5-158.5 GHz,
168.59-168.93 GHz,
171.11-171.45 GHz,
172.31-172.65 GHz,
173.52-173.85 GHz,
195.75-196.15 GHz,
209-226 GHz,
241-250 GHz,
252-275 GHz
are allocated, administrations are urged to take all practicable steps to protect the radio astronomy service from harmful interference. Emissions from spaceborne or airborne stations can be particularly serious sources of interference to the radio astronomy service (see Nos. 4.5 and 4.6 and Article 29). (WRC 07)
5.338A In the frequency bands 1 350-1 400 MHz, 1 427-1 452 MHz, 22.55-23.55 GHz, 24.25-27.5 GHz, 30-31.3 GHz, 49.7 50.2 GHz, 50.4-50.9 GHz, 51.4-52.4 GHz, 52.4-52.6 GHz, 81-86 GHz and 92-94 GHz, Resolution 750 (Rev.WRC 19) applies. (WRC 19)
5.532A The location of earth stations in the space research service shall maintain a separation distance of at least 54 km from the respective border(s) of neighbouring countries to protect the existing and future deployment of fixed and mobile services unless a shorter distance is otherwise agreed between the corresponding administrations. Nos. 9.17 and 9.18 do not apply. (WRC 12)
US145   The following unwanted emissions power limits for non-geostationary satellites operating in the inter-satellite service that transmit in the band 22.55-23.55 GHz shall apply in any 200 MHz of the passive band 23.6-24 GHz, based on the date that complete advance publication information is received by the ITU’s Radiocommunication Bureau:

    (a) For information received before January 1, 2020: −36 dBW/200 MHz.

    (b) For information received on or after January 1, 2020: −46 dBW/200 MHz.
US278 In the bands 22.55-23.55 GHz and 32.3-33 GHz, non-geostationary inter-satellite links may operate on a secondary basis to geostationary inter-satellite links.

US342 In making assignments to stations of other services to which the bands:

13 360-13 410 kHz	42.77-42.87 GHz*
25 550-25 670 kHz	43.07-43.17 GHz*
37.5-38.25 MHz	43.37-43.47 GHz*
322-328.6 MHz*	48.94-49.04 GHz*
1330-1400 MHz*	76-86 GHz
1610.6-1613.8 MHz*	92-94 GHz
1660-1660.5 MHz*	94.1-100 GHz
1668.4-1670 MHz*	102-109.5 GHz
3260-3267 MHz*	111.8-114.25 GHz
3332-3339 MHz*	128.33-128.59 GHz*
3345.8-3352.5 MHz*	129.23-129.49 GHz*
4825-4835 MHz*	130-134 GHz
4950-4990 MHz	136-148.5 GHz
6650-6675.2 MHz*	151.5-158.5 GHz
14.47-14.5 GHz*	168.59-168.93 GHz*
22.01-22.21 GHz*	171.11-171.45 GHz*
22.21-22.5 GHz	172.31-172.65 GHz*
22.81-22.86 GHz*	173.52-173.85 GHz*
23.07-23.12 GHz*	195.75-196.15 GHz*
31.2-31.3 GHz	209-226 GHz
36.43-36.5 GHz*	241-250 GHz
42.5-43.5 GHz	252-275 GHz

are allocated (*indicates radio astronomy use for spectral line observations), all practicable steps shall be taken to protect the radio astronomy service from harmful interference. Emissions from spaceborne or airborne stations can be particularly serious sources of interference to the radio astronomy service (see ITU Radio Regulations at Nos. 4.5 and 4.6 and Article 29).

Wiki entries

Common Carrier Fixed Point-to-Point Microwave

Current Use 21.2–23.6 GHz Common Carrier Fixed Point-to-Point Microwave (max bandwidth 50 MHz)

These bands are permitted for use by common carrier fixed point-to-point microwave systems under Part 101, Subparts C & I of the FCC rules.

Possible MSS Allocations (WRC-15 Agenda Item 1.10)

Proposed Use 22–26 GHz Possible MSS allocations (WRC-15 agenda item 1.10)

Agenda item 1.10 of the 2015 World Radiocommunication Conference:

"to consider spectrum requirements and possible additional spectrum allocations for the mobile-satellite service in the Earth-to-space and space-to-Earth directions, including the satellite component for broadband applications, including International Mobile Telecommunications (IMT), within the frequency range 22 GHz to 26 GHz, in accordance with Resolution 234 (WRC-12)"

Iridium

Current Use 22.55–23.55 GHz Iridium inter-satellite links

Iridium is a mobile-satellite service (MSS) system that was first licensed by the FCC in 1995, and began commercial service in 1998.

Iridium utilizes an FDMA/TDMA Time Division Duplex (TDD) access technology, so that the same frequency band is used for both the user uplink and downlink transmissions, on a time-shared basis. It shares a portion of its spectrum (1617.775-1618.725 MHz) with Globalstar, which has mobile uplinks to its own MSS system in the 1610-1618.725 MHz band.

Each Iridium user uplink/downlink channel has a bandwidth of 31.5 kHz and is separated in frequency by 41.67 kHz to allow for Doppler shift. A single Iridium TDMA frame is 90 ms long, which begins with 22.48 ms guard time, followed by four user uplink and four user donwlink time slots (8.28 ms burst time each, separated by small guard times).

A good discussion of the Iridium system architecture, constellation design, and multi-access scheme can be found in chapter 2 of the thesis by Abdul Jabbar (link below).

In February 2013, Iridium was granted authority by the FCC to provide aeronautical mobile-satellite (route) service (AMS(R)S) in the 1618.725-1626.5 MHz portion of its spectrum, limited to oceanic, polar, and remote regions. According to the FCC, "for purposes of this authorization, we consider oceanic regions to be those beyond 12 nautical miles from the baselines of the coastal states." Authorization for remote areas of other territories is contingent upon completing the agreement-seeking process under 5.367 of the ITU Radio Regulations.

At the end of 2012, Iridium reported approximately 368,000 subscribers. The company plans to launch a new generation of satellites, Iridium Next, beginning in 2015.