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Satellite issues: Earth stations in motion (ESIM)

​​​​​​​​​​​​Satellite issues


Challenges and solutions

Earth stations in motion (ESIM) communicate, currently, with geostationary-satellite orbit (GSO) systems operating in the fixed-satellite service (FSS) and operate on platforms in motion in the frequency ranges 17.7-20.2 GHz (space-to-Earth) and 27.5-30 GHz (Earth-to-space).

Historically, communication services to mobile platforms were usually provided by satellite systems in the mobile-satellite service (MSS) using relatively low-frequency bands (e.g. the 1.5 GHz, 1.6 GHz, 2.1 GHz, and 2.4 GHz bands). The frequency bandwidths available to individual users in these ranges are relatively low - typically a few kHz to a few hundred kHz. The narrow frequency bandwidths available limit the data rates that can be achieved, which range from a few kbit/s to around 700 kbit/s in a single channel.

The typical data rates currently provided by terminals operating in networks serving ESIMs are around 100 Mbit/s. Data rates may increase to support greater broadband demand or be reduced for applications using smaller earth station antennas while still supporting much higher data rates than are available over existing MSS systems. ITU studies examine how to deliver higher data rates, without impacting other and existing services adversely.

When ships are at sea or aircraft cross the oceans, they are out of reach of terrestrial networks. For such craft on or over vast oceans, an ESIM system can resolve this challenge by providing continuous broadband connectivity for crew and passengers.

ESIMs provide broadband communications on cruise ships, the largest of which can accommodate several thousands of passengers. In addition, ESIM stations can provide broadband communications for managing ship operations, such as for transmission of engine diagnostics, as well as for access to the ship operator's corporate network and for its crew's communications.

In addition, ESIMs meet the broadband connectivity requirements of land vehicles, including trains, coaches, vans, trucks, and motorhomes. Land ESIM can provide connectivity throughout countries and are particularly useful in areas that are not served by terrestrial networks.

ESIM applications also exist for government users and aid organizations that have broadband communication needs for land vehicles, ships, and aircraft. For example, when telecommunications infrastructure is down due to natural disasters, land ESIM can be vital. 

ITU’s contribution


ITU Member States agreed at the WRC-19 in Sharm el-Sheikh, Egypt to a new Resolution that will boost the deployment of ESIM: to address the increasing need for radio-frequency spectrum for ESIM, while protecting other radio services, WRC-19 agreed on the regulatory and technical conditions under which the frequency bands 17.7‑19.7 GHz (space-to-Earth) and 27.5-29.5 GHz (Earth-to-space) can be used by the three types of ESIM communicating with geostationary (GSO) space stations in the fixed-satellite service (FSS).

The new Resolution starts by stating that “there is a need for global broadband mobile-satellite communications, and that some of this need could be met by allowing earth stations in motion (ESIMs) to communicate with space stations of the geostationary-satellite orbit (GSO) fixed-satellite service (FSS) operating in the frequency bands 17.7-19.7 GHz (space-to-Earth) and 27.5-29.5 GHz (Earth-to-space)."

However, the Resolution also cautions that the frequency bands 17.7-19.7 GHz (space-to-Earth) and 27.5-29.5 GHz (Earth-to-space) “are also allocated to terrestrial and space services used by a variety of different systems, and these existing services and their future development need to be protected, without the imposition of undue constraints, from the operation of ESIMs."

Considering the above, the Resolution lays out technical, operational, and regulatory conditions for any ESIM communicating with a GSO FSS space station in the frequency bands 17.7-19.7 GHz and 27.5-29.5 GHz, or parts thereof.

WRC-19 also decided to continue studies on this issue for the 2023 WRC, where the use of the frequency bands 17.7-18.6 GHz, 18.8-19.3 GHz and 19.7-20.2 GHz (space-to-Earth) and 27.5-29.1 GHz and 29.5-30 GHz (Earth-to-space) by ESIM communicating with non-geostationary satellites in the fixed-satellite service will be addressed together with a potential additional 500 MHz of new spectrum being identified for ESIM communicating with geostationary satellites in the fixed-satellite service in the frequency band 12.75-13.25 GHz (Earth-to-space). 


Last update: March 2022  ​