iar with GPS. GPS projects were initiated by the US Department of Defense in 1973. GPS uses satellite signals to help find a location on earth (https://aerospace.org/article/ brief-history-gps) At a high level, the GPS system has three main components, as shown in Figure 16.7, namely the following: Control segment Space segment User segment Introduction to satellite communications Data to GPS satellite Space segment Data from Navigation Data GPS satellite from GPS satellite Control Segment User Segment Figure 16.7 - Architecture of satellite systems The control segment is the earth-based system that manages the satellite communication system. The space segment is a Geosynchronous Equatorial Orbiting (GEO) satellite that goes around the earth. The user segment is the GPS device in the car or, going forward, the smartphone. The GEO satellite orbits about 35.8 kilometers above the earth and the propagation delay for the round trip is about half a second. While for location services, a 0.5-second delay may be acceptable, it may be too much latency for other services typically supported by a smartphone. LEO satellites significantly reduce the latency to below 50 milliseconds. In the context of the positioning system, we often reference the Global Navigation Satellite System (GNSS). GNSS consists of a constellation of satellites, around the earth. This collection of satellites transmits a signal with positioning and timing data to GNSS receivers. This information is used to determine the precise location on the earth (https://www.euspa.europa.eu/european- space/eu-space-programme/what-gnss). A nice video explaining GNSS can be found here:https://www.youtube.com/ watch?v=gffG5sTegT4&t=157s Next, we'll look at considerations for satellite communication in 5G. 5G and Satellite Communications Satellite communication in 5G Satellite communication adds the satellite network to the network infrastructure of 5G. Since satellites have a global reach, they can be used for the following: Data distribution to many regions TV broad