LANDMARC : Indoor Location Sensing Using Active RFID Student :Yi-Shyuan WU Adviser : Kai-Wei Ke Date :

Outline Introduction of location-aware systems RFID technology LANDMARC approach LANDMARC system Some effect and Influence in LANDMARC system Conclusion References

location-aware application — three principal technique Triangulation – uses the geometric properties of triangles to compute object locations.  Lateration : using distance measurements.  Angulation : using primarily angle or bearing measurements Scene analysis – uses features of a scene observed from a particular vantage point to draw conclusions about the location of the observer or of objects in the scene Proximity – A proximity location-sensing technique entails determining when an object is “ near ” a known location.

location-aware system Outdoor:  GPS(Global Positioning System) Indoor:  Infrared used diffuse infrared technology  RADAR is an RF based system, is not as optimal as desired  Ultrasonic Cricket Location Support System & Active Bat location system, high effective and accurate, and cost is exorbitant

location-aware system Indoor:  RFID(SpotON use received radio SSI)  / Ultra-wideband  /Zigbee 的定位導覽系統

RFID technology Radio Frequency Identification Reader 、 Tag(Transponder) Host ( 主電腦應用系統 ) 、 antenna

RFID technology — Reader RFID Reader 包含 :  與主電腦相連接的介面 RS232 、 RS485 、 RS422 、 Bluetooth 、  控制電路、收發模組與收發天線 控制電路包含 Microcontroller 用來控制 收發模組與收發天線發射 RF 無線電波對 Tag 進行讀取與寫入的動作

Transponder RFID technology — Tag

RFID technology — 操作原理 Reader: 當主電腦下辨識命令給 Reader 時,Reader 透過 Antenna 發射 RF 無線電波, Tag 在偵測範圍內即透過 RF 機制傳回給 Reader, 再傳回給電腦進行辨識 Tag: 進入偵測範圍時, 其內的 Antenna 感應到 電磁能量後, 其 RF 收發機制感應耦合出電流, 再經過電容充電成可用電源 (Passive), 將資 料傳回給 Reader

RFID technology — 國際標準之缺乏 在國際標準方面，因涉及各國之法令、利 益及各大廠商之利害關係 RFID 系統中，須標準化的流程有 :  Air Interface 與 Data Management 之標準化。  Reader 與 Host Computer 間之 Interface 。 目前 RFID 的國際標準及組織  ISO 標準 :ISO 大眾運輸票價卡、 ISO 門禁卡  EPC :MIT Auto ID Center 提出的是一個電子產 品碼 Electronic Product Code (EPC )

LANDMARC approach LANDMARC( Location Identification based on Dynamic Active RFID Calibration ) Idea of having extra fixed location reference tags to help location calibration SSI( signal strength information ) & Power Level( 1-8 in LANDMARC system)

LANDMARC approach Advantage: – No need for a large number of expensive RFID reader. – Environmental dynamic can easily be accommodated. – Location information is more accurate and reliable.

LANDMARC system LANDMARC system includes RF Reader, Reference Tag and Tracking Tag. – RF Reader : using IEEE b wireless network – Reference Tag : Serve as reference points in the system – Tracking Tag / Moving Tag

LANDMARC system

LANDMARC system setup System setup — API software (1/2) 1. Device ( RF readers )setup : Configuring the IP address. 2. Range : Specify what range for tags is to be scanned. 3. Time/tag limit per log file : How long and how much tag events recorded, somewhat critical to the configuration in sense of its effect on efficiency.

LANDMARC system setup System setup — API software (2/2) 4. Mode( Exception vs. Continuous ) :  Exception mode : The reader will report the tag when it is inside the detected range while it will not report again until the reader realizes the tag has gone out of range.  Continuous mode : The reader will continuously report the tag ID as long as it was in the configured range.

LANDMARC system Methodology Methodology Suppose : n RF readers m reference tags u tracking tags Readers configured with continuous mode and detection-rang of 1-8

LANDMARC system Methodology Define : Signal Strength Vector of tracking tags Signal Strength Vector of reference tags, denotes the tracking tag, reference tag received on reader i, where

LANDMARC system Methodology Define : Euclidean distance in signal strength between a tracking tag and a reference tag j When there are m reference tags, a tracking tag has its E vector as

LANDMARC system Methodology The process of locating the unknown tracking tags have three key issues: 1.The placement of the reference tags 2.To determine the number of reference tags in a reference cell k-nearest neighbor algorithm ( =1/k ?) 3.To determine the weights assigned to different neighbors

LANDMARC system Experimental results and performance evaluation Define the location estimation error e: real coordinates, computed coordinates

LANDMARC system Effect of the number of nearest neighbors k=2~5 k=4 works the best set k=4 as the value of k

LANDMARC system Cumulative percentile of error distance for k from 2 to 5.

LANDMARC system Influence of the environmental factors  Time: 10 groups of data from midnight to early morning 10 groups of data from 10:00 Am to 3:00 PM  Tracking Tag placement: Two placement

LANDMARC system Cumulative percentile of error distance in the daytime and at night.

LANDMARC system Cumulative percentile of error distance between two tracking tag placement configurations

LANDMARC system Effect of the number of readers  More RF readers to deal with non-line of sight (NLOS) which create the multi-path problem.  With more RF readers, more data can be gathered by having extra readers to do the sensing

LANDMARC system Cumulative percentile of error distance for 3 and 4 RF readers.

LANDMARC system Effect of placement of reference tags  Partition ( or sometimes a person standing)  Placement more reference tags Higher reference tag density lower reference tag density

LANDMARC system

Higher reference tag density

LANDMARC system Cumulative percentile of error distance with a higher reference tag density

LANDMARC system lower reference tag density

LANDMARC system Cumulative percentile of error distance with a lower reference tag density

Conclusion Although active RFID is not designed for accurate indoor location sensing, LANDMARC approach does show that active RFID is a viable cost-effective candidate for indoor location sensing. Three problem :  SSI & Power level  Long latency  Variation of the behavior of tags

References Lionel M. Ni, "LANDMAC ： Indoor Location Sensing Using Active RFID," IEEE International Conference in Pervasive Computing and Communications 2003 (IEEE PerCom 2003) ， Dallas ， TX ， USA ， March 2003 P. Bahl and V. N. Padmanabhan., "RADAR ： An In- Building RF-based User Location and Tracking System," In Proc. of Joint Conference of the IEEE Computer and Communications Societies (INFOCOM), J. Hightower and G. Borriello, A survey and taxonomy of location sensing systems for ubiquitous computing, CSE , University of Washington, Department of Computer Science and Engineering, Seattle, WA (August 2001), ower2001survey/hightower2001survey.pdf RFID 系統入門 - 無線射頻辨識系統 陳宏宇 / 著. 松崗