There will soon be four Global Navigation Satellite Systems (GNSS): GPS (US), Glonass (Russia), Galileo (Europe) and Compass (China). Add to this the Regional Navigation Satellite Systems (RNSS) of Beidou (China), QZSS (Japan) and the Indian RNSS (IRNSS), and the Space-Based Augmentation Systems (SBAS), and within 5 years there may be over 50 navigation satellites visible at any one time in the “hot spot” of Asia and Australia.
This collection of satellite navigation constellations has been referred to as a “System of Systems” (SoS), highlighting the fact that there are advantages in exploiting all of the available satellites, and their multiple broadcast frequencies and signals. In this paper, we discuss what some of the advantages of extra satellites and signals are likely to be, and how “System of Systems” receivers differ from conventional receivers. For example, compared to a single constellation, more transmitting navigation satellites delivers higher accuracy, integrity, and availability (especially in restricted environments such as urban canyons).
In this paper, we examine the implications for receivers of the SoS requirements, from antenna and front end, through to digital baseband and measurement processing. Drawbacks to the SoS approach include far more complex hardware and software. Initial estimates of power consumption, for instance, show that these receivers could discharge a battery 200 times faster than a conventional receiver!