https://www.ronpub.com/ojiot/OJIOT_2015v1i2n03_Cho.html Channel of the paper: Ho-sik Cho, Jianxun Ji, Zili Chen, Hyuncheol Park and Wonsuk Lee: Accurate Distance Estimation between Things: A Self-correcting Approach, Open Journal of Internet Of Things (OJIOT), 1 (2), pages 19-27, URN: urn:nbn:de:101:1-201704244959, 2015 en-us https://www.ronpub.com/ojiot/OJIOT_2015v1i2n03_Cho.html http://nbn-resolving.de/urn:nbn:de:101:1-201704244959 This paper suggests a method to measure the physical distance between an IoT device (a Thing) and a mobile device (also a Thing) using BLE (Bluetooth Low-Energy profile) interfaces with smaller distance errors. BLE is a well-known technology for the low-power connectivity and suitable for IoT devices as well as for the proximity with the range of several meters. Apple has already adopted the technique and enhanced it to provide subdivided proximity range levels. However, as it is also a variation of RSS-based distance estimation, Apple's iBeacon could only provide immediate, near or far status but not a real and accurate distance. To provide more accurate distance using BLE, this paper introduces additional self-correcting beacon to calibrate the reference distance and mitigate errors from environmental factors. By adopting self-correcting beacon for measuring the distance, the average distance error shows less than 10% within the range of 1.5 meters. Some considerations are presented to extend the range to be able to get more accurate distances.