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.