As mentioned earlier, the Global Positioning System (GPS) is now a part of a growing international context—the Global Navigation Satellite System. One definition of GNSS embraces any constellation of satellites providing signals from space that facilitate autonomous positioning, navigation, and timing on a global scale. Currently, there is one other system besides GPS that satisfies this definition. It is the Russian Federation’s GLONASS, an acronym for Globalnaya Navigatsionnaya Sputnikovaya Sistema.
There are several other satellite systems in development that will likely reach similar capability soon and will take their place within the GNSS definition. In fact, some of them are considered by many to already fall under the GNSS label. These include the GALILEO system administered by the EU, the Chinese Beidou Navigation Satellite System (BDS), and regional systems such as the Indian Regional Navigation Satellite System (IRNSS) and the Japanese Quasi-Zenith Satellite System (QZSS) are often included as well.