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Wi-Fi positioning woes

Alice lives in India. She has super-cheap cellular internet (less than $0.2/GB on some networks). Cheap enough for it to be her daily driver, using a number of portable Wi-Fi routers, which just sit on her desk. And since it is so cheap and portable and convenient and long-lasting, she just carries it everywhere in her purse, wherever she travels.

Alice also hates her smartphones. She has gone through three phones in the past two years, and just her luck, that her GPS never works correctly. Whether she’s waiting at a crowded bus station on a clear day, trying to get an Uber, or stuck somewhere in a storm, again trying to get an Uber, her phone just fails to locate her correctly long enough to order a cab. And sometimes, her bad luck seems to be contagious to those around her too, with everyone complaining about their location being off by hundreds of miles, somewhere near Alice’s house.

Obtaining a device’s location is complicated. These days, smartphones take a lot of variables into account, which include GPS satellites, cell towers, bluetooth, and Wi-Fi to pinpoint the user in a fast and battery-efficient way. Basically, signal strength from different cell towers help triangulate your approximate location. Some BLE devices can advertise their location to nearby devices. Apart from that, Google/Apple/Microsoft maintain a huge list of (Wi-Fi SSID + MAC) => Location combinations to triangulate it even further. These methods are quite battery efficient (unlike GPS), and quick (unlike GPS).

Sometimes, due to these portable hotspots, your device might receive wrong/conflicting location data. And depending on your surroundings (GPS signal strength, number of Wi-Fi hotspots around you), you, and other people around you might see the device’s location constantly jumping between two points, or in some cases, a completely the wrong location.

So, the next time you see your location off by quite a distance, or just jumping around, try switching from A-GPS to GPS-only temporarily. It might be slow and power-hungry, but is accurate.

Example of Android's location settings

BTW, this is also how your PCs sometimes know their location. Eg- when you visit Google Maps.

- Sid Verma | Twitter