Localization by RFID ref: “LANDMARC: Indoor Location Sensing Using Active RFID”, PerCom’03 by: L. Ni, Y. Liu, Y. C. Lau, and A. P. Patil
Some Thought Solution 1: deploying many readers Solution 2: deploying many tags * Since RFID is not designed for location sensing, 8 different power levels: based on the signal strength received by the RFID reader, the reader will report or ignore the received ID, where power level 1 has the shortest range 2018/11/18
Goal of This Work to investigate whether the RFID technology is suitable for locating objects with accuracy and cost-effectiveness. LANDMARC: LocAtioN iDentification based on dynaMic Active RFID Calibration for in-building use. utilizing the concept of reference tags. 2018/11/18
LANDMARC Architecture: 1. readers 2. fixed tags 3. tracking tag 2018/11/18
LANDMARC Approach (I) In the sensing field: n readers m fixed tags u tracking tags (attached to a moving object) Readers are configured with continuous mode. Detection range = 1 ~ 8. Signal Strength Vector of a tracking tag: S=(S1, S2, …, Sn) Signal Strength Vector of a fixed tag i: Fi=(θ1, θ2, …, θn) *continuous mode: continuously reporting the tags that are within the specified range *detection-range of 1-8: reader will scan from range 1 to 8 and keep repeating the cycle with a rate of 30 seconds per range 2018/11/18
LANDMARC Approach (II) Euclidian distance between a tracking tag and the i-th fixed: Location of the tracking tag: pick the k fixed tags with the smallest “Euclidean distances” weighted location: 2018/11/18
Experiment Environment 2018/11/18
Environmental Factors: Daytime vs. Night Do not see much difference in the overall accuracy. *It shows the reference tag approach can successfully offset the dynamics of interference *effectively helps offset some of the environmental factors that contribute to the variations in a detected range 2018/11/18
Effect of n (Number of Readers) With more RF readers, a better decision can be made. 2018/11/18