Extending the Reach of GPS-assisted Femtocell Synchronization and Localization Through Tightly-Coupled Opportunistic Navigation

A strategy known as Tightly-Coupled Opportunistic Navigation (TCON) is proposed for extending the penetration of GPS-assisted femtocells in weak-signal indoor environments. Standards and regulatory agencies impose strict time, frequency, and location requirements on femtocells. These can be met with GPS aiding to unparalleled time and positioning accuracies, but GPS signals are extremely weak and thus difficult to acquire indoors. The results of this paper suggest that a TCON solution fusing GPS with CDMA cellular signals offers significant sensitivity gains over state-of-the-art assisted-GPS receivers, allowing GPS-synchronized femtocells to be deployed in 90% of all residences.