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Papers
2014 paper including an overview of the market then.
RF location tracking using WIFI with a precision on the meter scale.
Decimeter localization using a single WIFI access point.
Precise timing slides is needed for a precise position determination.
Ultra Wide Band
Bespoon offers module by uposition and Spoonphone at $50 and up.
Ekahau offers asset tracking.
Essensium offers an accuracy down to 50cm with it's Boomerand module.
Geozondas has a number of products for different applications.
Purelink offers asset tracking and badges. Sewio offers a number of kits.
Sewio packet sniffer localization demo video using 802.15.4a.
Time Domain offers the PulsON 330 and 440.
The Russian contender UWBS offers a number of products
Bluetooth
Commercial solution for iPhone and android using bluetooth at $59 and up from Estimote.
On Github
Open source example app using WIFI.
DW1000 from Decawave
Updated