1. 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

2. 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

3. 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

4. LANDMARC Architecture: 1. readers 2. fixed tags 3. tracking tag
2018/11/18

5. 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

6. 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

7. Experiment Environment
2018/11/18

8. 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

9. Effect of n (Number of Readers)
With more RF readers, a better decision can be made.
2018/11/18