GPS Performances

GPS
Title	GPS Performances
Author(s)	GMV
Level	Basic
Year of Publication	2011

Combined services performances

Galileo is being designed to be interoperable with other systems and, therefore, it will, in a great many instances, be used as part of a combined service. The identification of combined services is necessary to:

• Meet the most demanding user applications.
• Reduce satellite navigation system weaknesses.
• Provide robust solutions for applications requiring system redundancy for safety and/or security reasons.
• Access future GNSS market.
• Enable and expand new market opportunities.

The most obvious systems to be combined with Galileo are the other existing GNSS systems, GPS,GLONASS, SBAS and GBAS as they share with Galileo many characteristics that facilitate a combination at user level. By combining Galileo with other GNSS systems, improved performance in the following domains can be expected:

• Availability: Using as an example Galileo in combination with GPS and SBAS systems, the number of operational satellites will be in the region of 60. In normal urban environments this would result in an increased availability for 4 satellites from 40% to more than 90%.
• Position Accuracy: Allied to an increased availability in restricted environments (urban) is a better geometry of spacecraft or enhanced positioning performance.
• Integrity: GNSS based integrity systems and techniques, such as SBAS, RAIM and GBAS, would benefit from the addition of new constellations, including Galileo, in terms of lower achievable protection levels and/or integrity risk.
• Redundancy: By combining services from separate and fully independent systems full redundancy can be achieved. This is particularly important for Safety of Life applications that require full system backup.