A method and system is described where a plurality of position reference devices use short-range wireless communication protocols to transmit positioning assistance data to nearby mobile devices, and the mobile devices use the assistance data to re-calibrate their positioning systems. In some embodiments, mobile device includes an accelerometer and the accelerometer measurements are used to calculate an updated velocity of the mobile device and an updated position of the mobile device based on the accelerometer measurements and previous velocity and position of the mobile device. The short-range communication methods include NFC, RFID, Bluetooth®, short-range 802.11, Wi-Fi Direct, and high frequency focused beams such as 60 GHz. The position reference devices are passive or active NFC tags, passive or active RFID tags, other devices that include such tags as their components, Bluetooth®-enabled devices, 60 GHz-enabled devices, and 802.11 access points that can lower their transmit power.