LANDMARC : Indoor Location Sensing Using Active RFID Student :Yi-Shyuan WU Adviser : Kai-Wei Ke Date...
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Transcript of LANDMARC : Indoor Location Sensing Using Active RFID Student :Yi-Shyuan WU Adviser : Kai-Wei Ke Date...
LANDMARC : Indoor Location Sensing Using Active RFIDStudent :Yi-Shyuan WUAdviser : Kai-Wei KeDate : 2006.3.14
Outline
Introduction of location-aware systems
RFID technologyLANDMARC approachLANDMARC systemSome effect and Influence in
LANDMARC systemConclusionReferences
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 technology802.11 RADAR is an RF based system, is not as optim
al 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)802.15.3/Ultra-wideband802.15.4/Zigbee 的定位導覽系統
RFID technology
Radio Frequency IdentificationReader 、 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 、 Bluetoot
h 、 802.11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 系統
Active Tag
Passive Tag
感應器標籤Sensor Tag
其他主動式標籤
EAS 防竊系統
LF低頻系統
HF`高頻系統
UHF極高頻系統
Microwave微波系統
ISO 14443通訊協定
ISO 15693通訊協定
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 14443 大眾運輸票價卡、 ISO 1
5693 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 802.11b 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, whereiS
),...,,( 21 nSSSS
i
),1( ni
),...,,( 21 n
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
n
i iij SE1
2)( ),1( mj
),...,,( 21 mEEEE
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
k
i iii yxwyx1
),(),(
k
ii
ij
E
Ew
1 2
2
1
1
iw
LANDMARC system
Experimental results and performance evaluation
Define the location estimation error e:
real coordinates, computed coordinates
20
20 )()( yyxxe
),( 00 yx
),( yx
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 an
d at night.
LANDMARC system
Cumulative percentile of error distance between two trac
king 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 tagsPartition
( or sometimes a person standing) Placement more reference tags
Higher reference tag density
lower reference tag density
LANDMARC system
LANDMARC system
LANDMARC system
LANDMARC system
Higher reference tag density
LANDMARC system
Cumulative percentile of error distance with a higher r
eference 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 levelLong latencyVariation 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), 2000.
J. Hightower and G. Borriello, A survey and taxonomy of location sensing systems for ubiquitous computing, CSE 01-08-03, University of Washington, Department of Computer Science and Engineering, Seattle, WA (August 2001), http://www.cs.washington.edu/homes/jeffro/pubs/hightower2001survey/hightower2001survey.pdf
RFID 系統入門 - 無線射頻辨識系統 陳宏宇 / 著 . 松崗