Indoor Location Sensing Using Active RFID Lionel M. Ni, HKUST Yunhao Liu, HKUST  Yiu Cho Lau, IBM Abhishek P. Patil, MSU L...
Motivation Overview of RFID Performance Evaluation LANDMARC Approach LANDMARC Conclusion
Why Indoors Location-Sensing ?
Location-aware Computing <ul><li>The location is an important context that changes whenever the object moves </li></ul><ul...
Location Sensing Techniques <ul><li>Triangulation: use geometric properties of triangle to compute object locations </li><...
Sensing Technologies <ul><li>Infrared </li></ul><ul><li>Ultrasonic  </li></ul><ul><li>Radio Frequency </li></ul><ul><ul><l...
Existing Technologies and Systems <ul><li>Infrared   </li></ul><ul><li>Example: Active Badge Location System   </li></ul><...
IEEE 802.11 Example: RADAR <ul><li>It is using a standard 802.11 network adapter to measure signal strengths at multiple b...
<ul><li>Strength </li></ul><ul><ul><li>Easy to set up </li></ul></ul><ul><ul><li>Requires few base stations </li></ul></ul...
Ultrasonic   <ul><li>Active Bat (AT&T) </li></ul><ul><ul><li>ultrasound time-of-flight measurement  </li></ul></ul><ul><ul...
Cricket Location Support System  (M.I.T) <ul><li>Ultrasonic time-of-flight and a radio frequency control signal  </li></ul...
RFID: SpotON  <ul><li>Objects are located by homogenous sensor nodes without central control  </li></ul><ul><li>SpotOn tag...
LANDMARC Prototype <ul><li>Selection  criteria </li></ul><ul><ul><li>Use commodity products or off-the-shelf components </...
What is RFID  (Radio Frequency Identification)   ? <ul><li>RFID is a means of storing and retrieving data through electrom...
Passive RFID
Active RFID <ul><li>RF Reader </li></ul><ul><ul><li>Range up to 150 feet </li></ul></ul><ul><ul><li>Identify 500 tags in 7...
Active RFID Advantages <ul><li>Non-line-of-sight nature  </li></ul><ul><li>RF tags can be read despite the extreme environ...
Using RFID: First Attempt <ul><li>How many readers are needed? </li></ul><ul><ul><li>Build an array of readers: too expens...
<ul><li>the received signal power at distance is given by </li></ul><ul><li>free space loss  is given by </li></ul>
Difficulties
LANDMARC Approach <ul><li>The LANDMARC system mainly consists of two physical components, the RF readers and RF tags   </l...
The Concept of Reference Tags
<ul><li>Distance estimation </li></ul><ul><li>Placement of reference tags </li></ul><ul><li>Selection of k neighboring ref...
Three Key Issues the placement of the reference tags   •   the value of  k  in this algorithm  •   the formula of the weig...
Distance Estimation: Signal Strength <ul><li>Signal Strength Vector of an unknown tag  </li></ul><ul><li>Signal Strength V...
 
 
Effect of the Value k  Cumulative Percentile Of Error Distance When K Value Is 2, 3, 4, 5
Influence of  The Environmental Factors   <ul><li>Cumulative Percentile Of Error Distance in Daytime & Night   </li></ul>
Influence of  The Environmental Factors (cont’d) <ul><li>Change The Placements Of Tracking Tags   </li></ul>
Influence of  The Environmental Factors (cont’d) <ul><li>Cumulative Percentile Of Error Distance When Changing The Placeme...
Effect of  The Number of Readers   <ul><li>Cumulative Percentile Of Error Distance With 3 or 4 Readers Data  </li></ul>
The Effect of Placement of Reference Tags   <ul><li>Without Partition </li></ul>
Effect of Placement of Reference Tags (cont’d)   <ul><li>With Partition </li></ul>
Effect of Placement of Reference Tags (cont’d)   <ul><li>With Partition </li></ul>
Placement of Reference Tags <ul><li>Replacements of the Reference Tags with a Higher Density   </li></ul>
Effect of Higher Density Reference Tags <ul><li>Cumulative Percentile Of Error Distance With Higher Reference Tag Density ...
Lower Density of Reference Tags <ul><li>Replacements of the Reference Tags with a Lower Density   </li></ul>
Effect of Lower Density Reference Tags <ul><li>Cumulative Percentile Of Error Distance With lower Reference Tag Density   ...
<ul><li>Using 4 RF readers in the lab, with one reference tag per square meter,  accurately locate the objects within erro...
Conclusions <ul><li>RFID can be a good candidate for building location-sensing systems  </li></ul><ul><li>Able to handle d...
Questions?
Thank you !
Desk Refrigerator Desk Desk Sofa Refrigerator 2. Tracking movement 3. Notify where you are (Location sensing) 4. Notify yo...
Triangulation   <ul><ul><li>Lateration </li></ul></ul><ul><ul><ul><li>Direct </li></ul></ul></ul><ul><ul><ul><li>Time-of-f...
<ul><li>Scene Analysis </li></ul><ul><li>use features of a scene observed from a certain reference point </li></ul><ul><li...
Project Motivation <ul><li>GPS’s inability for accurate indoor location sensing </li></ul><ul><li>Develop a cost-effective...
Passive RFID vs. Active RFID Active tag System
A Triangulation Approach   A  Triangulation Approach
 
Active RFID <ul><li>RF Reader </li></ul><ul><ul><li>Range up to 150 feet </li></ul></ul><ul><ul><li>Identify 500 tags in 7...
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  • The last one may need rephrase Plenty of other application scenarios, depending on your imagination and creativity
  • Indoor Location Sensing Using Active RFID

    1. 1. Indoor Location Sensing Using Active RFID Lionel M. Ni, HKUST Yunhao Liu, HKUST Yiu Cho Lau, IBM Abhishek P. Patil, MSU LANDMARC
    2. 2. Motivation Overview of RFID Performance Evaluation LANDMARC Approach LANDMARC Conclusion
    3. 3. Why Indoors Location-Sensing ?
    4. 4. Location-aware Computing <ul><li>The location is an important context that changes whenever the object moves </li></ul><ul><li>Location-aware services allow to offer value-added service to the user, depending on their current geographic position and will be a key feature of many future mobile applications </li></ul><ul><li>Sensing the location: explicit and implicit cooperation; outdoor or indoor </li></ul>
    5. 5. Location Sensing Techniques <ul><li>Triangulation: use geometric properties of triangle to compute object locations </li></ul><ul><ul><li>Signal strength: signal attenuation is a function of distance to the signal source </li></ul></ul><ul><li>Scene analysis: use features of a scene observed from a certain reference point </li></ul><ul><li>Proximity: determine if an object is near a known location </li></ul>
    6. 6. Sensing Technologies <ul><li>Infrared </li></ul><ul><li>Ultrasonic </li></ul><ul><li>Radio Frequency </li></ul><ul><ul><li>RFID </li></ul></ul><ul><ul><li>802.11 </li></ul></ul><ul><ul><li>Bluetooth </li></ul></ul><ul><li>Others </li></ul>
    7. 7. Existing Technologies and Systems <ul><li>Infrared </li></ul><ul><li>Example: Active Badge Location System </li></ul><ul><li>Low power requirements </li></ul><ul><li>Low circuitry costs: $2-$5 for the entire coding/decoding circuitry </li></ul><ul><li>Simple circuitry </li></ul><ul><li>Higher security </li></ul><ul><li>Portable </li></ul><ul><li>High noise immunity </li></ul><ul><li>Line-of-sight </li></ul><ul><li>Coarse resolution </li></ul><ul><li>Short range </li></ul><ul><li>Blocked by common materials </li></ul><ul><li>Light, weather sensitive </li></ul><ul><li>Pollution can affect transmission </li></ul>
    8. 8. IEEE 802.11 Example: RADAR <ul><li>It is using a standard 802.11 network adapter to measure signal strengths at multiple base stations positioned to provide overlapping coverage in a given area </li></ul>
    9. 9. <ul><li>Strength </li></ul><ul><ul><li>Easy to set up </li></ul></ul><ul><ul><li>Requires few base stations </li></ul></ul><ul><ul><li>Uses the same infrastructure that provides general wireless networking in the building </li></ul></ul><ul><li>Weakness </li></ul><ul><ul><li>Poor overall accuracy: </li></ul></ul><ul><ul><ul><li>scene-analysis: within 3 meters with 50 percent probability </li></ul></ul></ul><ul><ul><ul><li>signal strength: 4.3 meters at the same probability </li></ul></ul></ul><ul><ul><li>Support Wave LAN NIC </li></ul></ul>Microsoft RADAR
    10. 10. Ultrasonic <ul><li>Active Bat (AT&T) </li></ul><ul><ul><li>ultrasound time-of-flight measurement </li></ul></ul><ul><ul><li>can locate Bats to within 9cm of their true position for 95 percent of the measurements </li></ul></ul>
    11. 11. Cricket Location Support System (M.I.T) <ul><li>Ultrasonic time-of-flight and a radio frequency control signal </li></ul><ul><li>Lateration and proximity techniques </li></ul><ul><li>Decentralized scalability </li></ul><ul><li>4x4 square-foot regions </li></ul>Listener Beacon
    12. 12. RFID: SpotON <ul><li>Objects are located by homogenous sensor nodes without central control </li></ul><ul><li>SpotOn tags use received radio signal strength information as a sensor measurement for estimating inter-tag distance </li></ul><ul><li>No complete system yet </li></ul>
    13. 13. LANDMARC Prototype <ul><li>Selection criteria </li></ul><ul><ul><li>Use commodity products or off-the-shelf components </li></ul></ul><ul><ul><li>Low cost </li></ul></ul><ul><ul><li>Resolution: no more than 2-3 meters </li></ul></ul><ul><li>Decision: RFID technology </li></ul>
    14. 14. What is RFID (Radio Frequency Identification) ? <ul><li>RFID is a means of storing and retrieving data through electromagnetic transmission to a RF compatible integrated circuit </li></ul><ul><li>3 basic components </li></ul>
    15. 15. Passive RFID
    16. 16. Active RFID <ul><li>RF Reader </li></ul><ul><ul><li>Range up to 150 feet </li></ul></ul><ul><ul><li>Identify 500 tags in 7.5 seconds with the collision avoidance </li></ul></ul><ul><ul><li>Support 8 power levels (function of distance) </li></ul></ul><ul><li>Active Tag system </li></ul><ul><ul><li>Emit signal, which consists of a unique 7-character ID, every 7.5 seconds for identification by the readers </li></ul></ul><ul><ul><li>Button-cell battery (2-5 years life) </li></ul></ul><ul><ul><li>Operate at the frequency of 303.8 MHz </li></ul></ul>
    17. 17. Active RFID Advantages <ul><li>Non-line-of-sight nature </li></ul><ul><li>RF tags can be read despite the extreme environmental factors : snow, fog, ice, paint … </li></ul><ul><li>be read in less than 100 milliseconds </li></ul><ul><li>promising transmission range </li></ul><ul><li>cost-effectiveness </li></ul>
    18. 18. Using RFID: First Attempt <ul><li>How many readers are needed? </li></ul><ul><ul><li>Build an array of readers: too expensive </li></ul></ul><ul><li>How reliable is the tag detection? </li></ul><ul><ul><li>Not very reliable due to signal attenuation </li></ul></ul><ul><li>Placement of RF readers </li></ul><ul><li>Cannot measure distance directly </li></ul>
    19. 19. <ul><li>the received signal power at distance is given by </li></ul><ul><li>free space loss is given by </li></ul>
    20. 20. Difficulties
    21. 21. LANDMARC Approach <ul><li>The LANDMARC system mainly consists of two physical components, the RF readers and RF tags </li></ul>
    22. 22. The Concept of Reference Tags
    23. 23. <ul><li>Distance estimation </li></ul><ul><li>Placement of reference tags </li></ul><ul><li>Selection of k neighboring reference tags </li></ul><ul><li>Weight of each selected reference tags </li></ul>Known Reference Tags
    24. 24. Three Key Issues the placement of the reference tags • the value of k in this algorithm • the formula of the weight •
    25. 25. Distance Estimation: Signal Strength <ul><li>Signal Strength Vector of an unknown tag </li></ul><ul><li>Signal Strength Vector of a reference tag </li></ul><ul><li>Euclidian distance </li></ul>
    26. 28. Effect of the Value k Cumulative Percentile Of Error Distance When K Value Is 2, 3, 4, 5
    27. 29. Influence of The Environmental Factors <ul><li>Cumulative Percentile Of Error Distance in Daytime & Night </li></ul>
    28. 30. Influence of The Environmental Factors (cont’d) <ul><li>Change The Placements Of Tracking Tags </li></ul>
    29. 31. Influence of The Environmental Factors (cont’d) <ul><li>Cumulative Percentile Of Error Distance When Changing The Placement Of Tracking Tags </li></ul>
    30. 32. Effect of The Number of Readers <ul><li>Cumulative Percentile Of Error Distance With 3 or 4 Readers Data </li></ul>
    31. 33. The Effect of Placement of Reference Tags <ul><li>Without Partition </li></ul>
    32. 34. Effect of Placement of Reference Tags (cont’d) <ul><li>With Partition </li></ul>
    33. 35. Effect of Placement of Reference Tags (cont’d) <ul><li>With Partition </li></ul>
    34. 36. Placement of Reference Tags <ul><li>Replacements of the Reference Tags with a Higher Density </li></ul>
    35. 37. Effect of Higher Density Reference Tags <ul><li>Cumulative Percentile Of Error Distance With Higher Reference Tag Density </li></ul>
    36. 38. Lower Density of Reference Tags <ul><li>Replacements of the Reference Tags with a Lower Density </li></ul>
    37. 39. Effect of Lower Density Reference Tags <ul><li>Cumulative Percentile Of Error Distance With lower Reference Tag Density </li></ul>
    38. 40. <ul><li>Using 4 RF readers in the lab, with one reference tag per square meter, accurately locate the objects within error distance such that the largest error is 2 meters and the average is about 1 meter. </li></ul>Overall Accuracy
    39. 41. Conclusions <ul><li>RFID can be a good candidate for building location-sensing systems </li></ul><ul><li>Able to handle dynamic environments </li></ul><ul><li>Suffer some problems </li></ul><ul><ul><li>Difference of Tags’ Behavior </li></ul></ul><ul><ul><li>RFID does not provide the signal strength of tags directly </li></ul></ul><ul><ul><li>Unable to adjust emitting interval </li></ul></ul><ul><ul><li>Standardization </li></ul></ul>
    40. 42. Questions?
    41. 43. Thank you !
    42. 44. Desk Refrigerator Desk Desk Sofa Refrigerator 2. Tracking movement 3. Notify where you are (Location sensing) 4. Notify your eating schedule 7. Time sensing 8. immobility sensing 11. Proximity sensing 16. Notify “ ok to eat” 1.walk 5.Stop eating 6.Back to desk 10. Walk around 9. Notify to move 12. Walk away from sofa 13. Distance& Time sensing 14. Notify to stop 15. Go back to desk 17. Go to kitchen 18. Refer Healthy food 19. Eat matched food An Obesity Care Case
    43. 45. Triangulation <ul><ul><li>Lateration </li></ul></ul><ul><ul><ul><li>Direct </li></ul></ul></ul><ul><ul><ul><li>Time-of-flight </li></ul></ul></ul><ul><ul><ul><li>Attenuation </li></ul></ul></ul><ul><ul><li>Angulation </li></ul></ul>
    44. 46. <ul><li>Scene Analysis </li></ul><ul><li>use features of a scene observed from a certain reference point </li></ul><ul><li>Proximity </li></ul><ul><ul><ul><li>determine if an object is near a known location </li></ul></ul></ul>
    45. 47. Project Motivation <ul><li>GPS’s inability for accurate indoor location sensing </li></ul><ul><li>Develop a cost-effective indoor location sensing infrastructure </li></ul><ul><li>Enables location-based Web services for mobile-commerce (m-commerce) environment </li></ul><ul><li>Plenty of other application scenarios, depending on your imagination and creativity </li></ul>
    46. 48. Passive RFID vs. Active RFID Active tag System
    47. 49. A Triangulation Approach A Triangulation Approach
    48. 51. Active RFID <ul><li>RF Reader </li></ul><ul><ul><li>Range up to 150 feet </li></ul></ul><ul><ul><li>Identify 500 tags in 7.5 seconds with the collision avoidance </li></ul></ul><ul><ul><li>Support 8 power levels (function of distance) </li></ul></ul><ul><li>Active Tag system </li></ul><ul><ul><li>Emit signal, which consists of a unique 7-character ID, every 7.5 seconds for identification by the readers </li></ul></ul><ul><ul><li>Button-cell battery (2-5 years life) </li></ul></ul><ul><ul><li>Operate at the frequency of 303.8 MHz </li></ul></ul>
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