Glossary
Definitions
9 definitions
ITU (International Telecommunication Union)
The United Nations specialised agency responsible for global coordination of radio spectrum and satellite orbital positions, whose Radio Regulations are the binding international treaty governing which frequency bands each service type can use and how orbital filings are coordinated.
ITU Filing
The formal submission made by a national administration to the ITU on behalf of a satellite operator, notifying other administrations of the planned satellite network's frequency and orbital parameters — the first step in securing international recognition and coordination priority for spectrum rights.
In-Flight Connectivity (IFC)
Satellite-based internet service delivered to passengers and crew aboard commercial aircraft in flight, with the global market reaching $6.3 billion in 2024 and over 10,000 equipped aircraft, powered by Ku-band and Ka-band VSAT and emerging LEO systems.
In-Orbit Servicing
The emerging capability of sending robotic spacecraft to rendezvous with existing satellites in orbit to refuel them, repair or replace components, extend their operational life, or modify their orbit — transforming satellites from disposable assets into maintainable infrastructure.
Inmarsat
A British GEO satellite operator founded in 1979, originally serving maritime distress communications, now operating L-band (Inmarsat-4), Ka-band Global Xpress (I-6), and EAN (European Aviation Network) services — acquired by Viasat in 2023, creating a global HTS satellite operator.
Intelsat
One of the world's largest GEO satellite operators, founded in 1964 as an intergovernmental organisation and privatised in 2001, operating 50+ GEO satellites across C, Ku, and Ka bands — completed a merger with SES in 2024 to create the world's largest commercial satellite operator.
Inter-Satellite Link (ISL)
A direct communication link between two satellites, using laser (optical) or radio frequency (RF) technology, enabling traffic routing across a constellation without touching the ground and reducing latency by avoiding the uplink-downlink round-trip via ground gateways.
IoT via Satellite
The use of satellite networks to connect sensors, trackers, and devices in remote areas beyond terrestrial cellular coverage — delivering small data packets (position, temperature, status) from ships, trucks, pipelines, weather stations, and agricultural equipment to cloud platforms via LEO or GEO constellations.
Iridium
The only mobile satellite operator with true pole-to-pole global coverage, operating 66 active LEO satellites at 781 km altitude with inter-satellite links — providing satellite phone, IoT (Iridium Short Burst Data), maritime, and aviation services through a second-generation Iridium NEXT constellation completed in 2019.