During his keynote speech at Apple's Worldwide Developers Conference in June 2008, Steve Jobs foreshadowed two industry trends with the announcement of the iPhone 3G: "Location services is going to be a really big deal on the iPhone... it's going to explode. We get location data from cell towers, from Wi-Fi, and now we also get it from GPS." The first trend is obvious: location services have indeed become a really big deal (with more than 1,000 location-enabled applications) on the iPhone and for the rest of the mobile industry. Google's recent announcement of free turn-by-turn navigation for mobile devices will only accelerate this trend. The second, less visible, trend is the blending of multiple (hybrid) location technologies in mobile devices. This article explains the linkage between the two trends and how hybrid location technology enables a better user experience of Location-based Services (LBS).

In his speech, Jobs explicitly mentioned three location technologies: Cell Tower Positioning (Cell-ID), Wi-Fi Positioning, and the Global Positioning System (GPS). Why three? Because each technology, in isolation, cannot meet the consumer expectations of quick and accurate determination of user location anywhere in the world. LBS are useful only when users' locations are known; it takes a blend of several technologies to reliably achieve this, adding to device cost and complexity.

Not all devices use the same mix of location technologies, but the three used in the iPhone are currently the most common. Others, such as the GLONASS satellite system, are likely to be joining them soon. TV Signals, Bluetooth, Radio Frequency Identification (RFIDs) and a variety of on-board sensors can also be used. Let's go deeper into the pros and cons of each common technology.

GPS

GPS is the leading location technology, since it enables the most accurate position calculation. On mobile devices, assistance data can be provided over the cellular network (A-GPS) to make the position calculation faster and more reliable. On networks that support A-GPS, user location can take less than 10 seconds, with accuracies approaching 5 meters. Although most smart phones today already have A-GPS capability, its usefulness starts to break down as the sky becomes more obstructed - in urban streets and especially indoors. This is why GPS technology by itself is insufficient.