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Satellite issues: Earth stations in motion (ESIM)

​​​​​​​​​​​​Satellite issues


Challenges and solutions


Earth stations in motion (ESIM) are earth stations that communicate 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 and 27.5-30 GHz.

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 ESIM are around 100 Mbit/s. Data rates may increase to support higher 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 crafts on or over vast oceans, an ESIM system can resolve this challenge by providing continuous broadband connectivity for passengers and crew.

ESIM 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 corporate network and for crew communications. The number of maritime vessels with a broadband connection by satellite grew by almost 25% between 2012 and 2013. In 2014, over 20 000 vessels were satellite connected and this number is expected to increase to around 50 000 vessels over the next few years. This strong growth has created greater demand for spectrum for ESIM.

In addition, ESIM 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 without coverage 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 information and communication infrastructure is down in natural disasters, land ESIM can be vital. 

ITU’s contribution

Delegates from around the world 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 services, delegates at WRC-19 decided 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."

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

In order to strike the right balance between the innovative services that ESIM are providing and the other applications using these frequency bands, the Resolution states that “transmitting aeronautical and maritime ESIM in the frequency band 27.5-29.5 GHz shall not cause unacceptable interference to terrestrial services to which the frequency band is allocated and operating in accordance with the Radio Regulations" and “transmitting land ESIMs in the frequency band 27.5-29.5 GHz shall not cause unacceptable interference to terrestrial services in neighbouring countries to which the frequency band is allocated and operating in accordance with the Radio Regulations."

Last update: Dec ​​2019 ​