Complementary ground component

File:Complementary Ground Component.jpg

A complementary ground component is a terrestrial infill system for a mobile-satellite service that uses terrestrial base stations to provide connectivity in weak signal areas, such as urban areas.{{cite web|url=https://www.theregister.com/2008/11/04/complementary_ground_components/|title=Ofcom tries to launch satellite plans again|author=Bill Ray|date=4 November 2008|publisher=The Register|accessdate=2010-07-26}} According to EU Decision 626/2008/EC:

:"complementary ground components" of mobile satellite systems shall mean ground-based stations used at fixed locations, in order to improve the availability of the mobile-satellite service in geographical areas within the footprint of the system's satellite(s), where communications with one or more space stations cannot be ensured with the required quality”{{cite web|url=https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX%3A32008D0626|title=DECISION No 626/2008/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 30 June 2008 on the selection and authorisation of systems providing mobile satellite services (MSS)|date=30 June 2008|accessdate=2010-07-26|publisher=Official Journal of the European Union}}, page L 172/17, para 18

Such systems use the same frequencies assigned for space usage.