Hybrid positioning system
Hybrid positioning systems are systems for finding the location of a mobile device using several different positioning technologies. Usually GPS (Global Positioning System) is one major component of such systems, combined with cell tower signals, wireless internet signals, Bluetooth sensors, IP addresses and network environment data, or other local Positioning Systems.
These systems are specifically designed to overcome the limitations of GPS, which is very exact in open areas, but works poorly indoors or between tall buildings (the urban canyon effect). By comparison, cell tower signals are not hindered by buildings or bad weather, but usually provide less precise positioning. Wi-Fi positioning systems may give very exact positioning, in urban areas with high Wi-Fi density - and depend on a comprehensive database of Wi-Fi access points.
Hybrid positioning systems are increasingly being explored for certain civilian and commercial location-based services and location-based media, which need to work well in urban areas in order to be commercially and practically viable.
Hybrid positioning systems are developed and used in services from Unwired Labs LocationAPI, Combain Mobile,AlterGeo,  Devicescape, Navizon, Google Maps for Mobile, openBmap, Opencellid for application in smartphones, PlaceEngine, Skyhook Wireless, Xtify. The maturity of the approaches used by these systems needs to be proved in operational use.
Early works in this area include the Place Lab project, which started on 2003 and went inactive in 2006. Later methods let smartphones combine the accuracy of GPS with the low power consumption of cell-ID transition point finding.
- AlterGeo: About us http://platform.altergeo.ru/index.php?mode=about
- Innovation: Hybrid Positioning http://www.gpsworld.com/gnss-system/algorithms-methods/innovation-hybrid-positioning-9628
- Skyhook Wireless - How it works. http://www.skyhookwireless.com/howitworks/xps.php
- AlterGeo - global location technology provider
- Combain Mobile http://www.combain.com/
- Navizon - Indoor positioning system
- Google Submission for Wifi collection
- Skyhook Wireless http://www.skyhookwireless.com/
- Energy-Efﬁcient Positioning for Smartphones using Cell-ID Sequence Matching by Jeongyeup Paek, Kyu-Han Kim, Jatinder P. Singh, Ramesh Govindan