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Satellite issues: Earth stations in motion (ESIM)


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

​Taking place in Egypt from 28 October to 22 November 2019, the ITU World Radiocommunication Conference (WRC-19) will decide 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).

Studies have been carried out on sharing and compatibility between ESIM and both space and terrestrial services allocated in the frequency bands above. These studies have identified sample regulations to protect services and sample guidelines to assist administrations in deploying ESIM on their territories. In addressing the spectrum needs of ESIM, due consideration has been taken of studies by the Radiocommunication Sector (ITU-R) and evidence available to date.

The technical, operational and regulatory responsibilities of bodies in charge of the operation, authorization and interference management of ESIM need to be defined for the three types of ESIM.

The frequency bands 19.7-20.2 GHz and 29.5-30 GHz are already available to ESIM operating in accordance with Resolution 156 (WRC-15). These bands are shared with terrestrial services in a limited number of countries and can accommodate ESIM operations with relatively limited technical and operational constraints.

The frequency bands within the scope of WRC-19 agenda item 1.5, specifically 17.7-19.7 GHz and 27.5-29.5 GHz, are allocated to several different services. The use of ESIM in some parts of these frequency bands may not be feasible in some geographic locations due to use by other services, which may need to be protected. For example, the frequency bands 27.8285-28.4445 GHz and 28.8365-29.4525 GHz are used by the fixed service in various countries in Europe based on its harmonized channel plan, and ESIM are not allowed to transmit on those same frequencies in some countries.

When ESIM operate in international waters and airspace, the responsible operators need to comply with appropriate technical limits to protect fixed services from harmful interference. To protect other services sharing the 27.5-29.5 GHz frequency band, different constraints could apply to different types of ESIM, as interference scenarios are different for maritime, aeronautical and land ESIM.

Furthermore, as ESIM move from one location to another or across borders, they may need to change their operating frequencies. To ensure continuity of service and meet user requirements, ESIM operators often consider it vital to operate within different parts of the frequency bands 17.7-19.7 GHz and 27.5-29.5 GHz, so they can access the full spectrum needed to provide service.​

Last update: June 2019 ​