Low satellite visibility areas: Extension of the GPS capabilities to deploy location-based services

Abstract

Global navigation satellite systems (GNSSs), such as the global positioning system (GPS), can be successfully used to fix a receiver position if at least four satellites are visible. This problem thwarts the usage of plain GPS receivers in many areas where the visibility of the GPS satellites is impaired. Such areas include highly populated metropolitan areas and business districts, where the GPS is typically used to deploy location-based services. To overcome this problem, GPS augmentation systems and terrestrial positioning systems are typically used. Nevertheless, they have high deployment costs and require unusual dedicated receivers. © 2005-2012 IEEE.