What is CGC (Complementary ground component)?

A complementary ground component is a framework for a mobile satellite service that utilizes terrestrial base stations to give availability in weak signal regions, like metropolitan areas.
The Complementary Ground Component is utilized to improve the satellite coverage in highly shadowed regions and to upgrade in-house coverage. The CGC is utilized in broadcasting and communication satellite frameworks that provide services to mobile users. The CGC utilizes a similar frequency range as the satellite itself.