Earth Stations in Motion (ESIMs) are the result of the most modern satellite technological developments and are designed to be used on aircraft, ships and land vehicles. They are small size terminals, with high-precision tracking capabilities, associated with state-of-the-art Ka-band satellites providing high-power multiple spot beam coverage, allowing transmission rates in the order of 10-50 Mbits/s.
Recognising that there is a need for global broadband mobile-satellite communications and that part of this need could be met by allowing ESIMs to communicate with fixed-satellite services (FSS) , the 2015 World Radiocommunication Conference (WRC‑15) decided to clarify that ESIMs can communicate with geostationary (GSO) FSS space stations using the 19.7-20.2 GHz (space-to-Earth) and 29.5-30.0 GHz (Earth-to-space) Ka-band radiofrequency spectrum. ESIMs’ use is subject to certain technical and operational conditions, which are specified in Resolution 156 (WRC-15).
In a related move, delegations gathered in Geneva for WRC-15 decided not to include the satellite Ka-band in the list of bands for study and future decision for globally harmonised use by terrestrial mobile broadband (5G).
The best solution for users on the move
These decisions by WRC-15 pave the way for satellite systems to provide global broadband connectivity for the transportation community, including aeronautical, maritime and land users.
The advances in satellite and earth station technology make ESIMs the best solution for users on the move and bring the benefits of high performance FSS networks to communities that have yet to benefit from true broadband offerings. This important decision is a big step towards the UN goal of connecting the unconnected.
The adopted regulatory framework for ESIMs as part of the ITU Radio Regulations will facilitate market access and leverage the deployment of this advanced technology in parts of the radio spectrum where satellites are able to deliver high power, multiple spot beams and broadband applications for ESIMs.
Inmarsat has recently completed deployment of a new generation satellite system, Global Xpress (GX), offering broadband mobile communications worldwide on land, at sea and in the air through the new constellation of Inmarsat-5 (I-5) Ka-band GSO FSS satellites.
User terminals for Inmarsat GX aeronautical, maritime and land applications, specifically to be deployed as ESIMs, will be provided by several equipment manufacturers. Terminals within the GX network provide rapid acquisition into the network, seamless transition from one beam to another and minimal outages when transitioning to a new satellite.
GX terminals will also immediately inhibit transmission when mispointing of their antenna would cause the exceedance of the off-axis EIRP levels above those specified in Resolution 156 (WRC‑15), Recommendation ITU-R S.524, ETSI EN 303 978 or above any other limits coordinated with neighbouring satellite networks under the usual ITU inter-system coordination procedures.
WRC-15 also decided that the next Conference – WRC-19 – should consider the use of the frequency bands 17.7-19.7 GHz (space-to-Earth) and 27.5- 29.5 GHz (Earth-to-space) by ESIMs communicating with GSO FSS space stations, taking into account the results of studies carried out by the ITU Radiocommunication Sector on:
- Technical and operational characteristics and user requirements of different types of ESIMs, including the use of spectrum to provide the envisioned services and the degree to which flexible access to spectrum can facilitate sharing with other services;
- Sharing and compatibility studies in order to ensure the adequate protection of current and planned stations of other services using the same frequency bands as ESIMs.