@article {gaglione2009, title = {Multi-Constellation System as Augmentation to GPS Performance in Difficult Environment or Critical Applications}, journal = {ATTI DELL{\textquoteright}ISTITUTO ITALIANO DI NAVIGAZIONE}, volume = {190}, year = {2009}, note = {Paper Selected from the ENC - 2009 Conference held in Naples on 4 - 6 May 2009}, pages = {{\textendash}}, abstract = {
The GPS Standard Positioning Service (SPS) does\ 
not provide suitable performance in all environment
conditions or in every possible applications. In\ 
severely signal degraded environments, e.g.\ 
mountainous or urban areas, where a lot of GPS\ 
signals are blocked by buildings or natural\ 
obstacles, the positioning is inaccurate because of
bad satellite configuration or impossible owing to\ 
lack of minimum number of visible satellites.\ 
Otherwise GPS SPS is inadequate for critical safety
applications like aircraft take-off or landing, because\ 
does not satisfy the Required Navigation Parameters
(RNP) relative to these flight phases.\ 
To solve the GPS gap on regional scale, space-based
augmentations could be employed. In this study a\ 
simulation is carried out, considering GLONASS\ 
and EGNOS GEO constellations and a set of 3\ 
geosynchronous satellites (similar to QZSS space\ 
segment). A software for constellation analysis is\ 
developed in MATLAB{\textregistered} environment to evaluate\ 
the considered augmentations performances in\ 
critical conditions (urban canyon or critical phase of\ 
flight). The used indicators to evaluate coverage\ 
performance are the VSN (Visible Satellites\ 
Number), DOP (Dilution of Precision) and the\ 
probability that integrity is available to be computed\ 
in autonomous.\ 
}, issn = {1120-6977}, author = {ANGRISANO, A and GAGLIONE, S and PACIFICO, A and VULTAGGIO, M} }