GPS tethering for energy conservation

Due to the low-speed GPS transmission and poor signal quality, localization is considered an expensive operation in battery-operated smartphones. This is even worse for apps that need a single location fix such as Foursquare and Flickr rather than continuous navigation because it cannot exploit the less-demanding 'warm start' mode of GPS operation. This paper proposes GPS-Tether (GTR) which shares and reuses the known GPS coordinates among mobile devices in the proximity. Benefiting from unremitting Wifi discovery behaviors of smartphones, GTR does not need an additional protocol and does not disrupt operations of non-GTR clients. Experiments based on Samsung Galaxy smartphones and Monsoon Power Monitor show that GTR can extend smartphones battery usage as much as 19% compared to Assisted GPS (A-GPS). One important design goal is that it should require minimal changes for the implementation of GTR, which has been accomplished by incorporating the Wifi virtualization technique.