Review & Pr esentation
Hybrid Context Inconsistency Resolution for Context-aware Services Chenhua Chen1, Chunyang Ye2, 3 and Hans-Arno Jacobsen2 Department of Computer Science, University of Saarland Middleware Systems Research Group, University of Toronto 3 Institute of Software, Chinese Academy of Sciences 1
2
Antenna ICÂ Chip Substrate Connection
Outline RF I D & D iscussion on Paper s
Outline Background ~ RFID Introduction ~ Context-awareness concepts Research Problem ~ Context Inconsistency Resolution Hybrid Solution ~ Context Correlation Model ~ Application Recovery Model Experimental Results Concluding Remarks References and Fun Thoughts
I ntr oductor y Wor ds: “ An Important Technology”
Tracking Technologies and Automatic ID Systems Various technologies are used to track and automatically ID people, products, and other objects – Barcodes – Optical Character Recognition (OCR) – Biometrics • Voice recognition and ID systems • Fingerprint ID systems
– Smart cards – Memory cards – Microprocessor cards
RF I D : What is it ? RFID combines many of the features of several of these technologies – Like barcodes, RFID is used to identify and track objects – As with OCR and biometrics, RFID enables automatic ID and verification – RFID also can be used like smart cards, memory card, and microprocessor cards to store information and provide interactive data processing
Most RFID tags contain at least two parts. One is an integrated circuit for storing and processing information, modulating and demodulating a (RF) signal, and other specialized functions. The second is an antenna for receiving and transmitting the signal.
H ow is RF I D unique? – It can be used to accurately locate and identify objects from a distance using RF signals – It can be used to detect and read objects that are not in line of sight –Data can be interactively managed and processed by the RFID chip and RFID system
M ar k et & Application Industrial Products
Logistics/ Trans.
Consumer Products
Retail Products
Homeland Security
Key Industry Drivers Leading Us Toward RFID
Other Service
Example: RF I D in L ibr ar ies
Simplifies checkout process for staff
Inventory of Collections
Use with new and future technology
Item Security
Express checkout for patrons
Cur r ent T echnology
Contexts locations, time etc. Implicit input/output Seamless integrated
Context-aw ar eness An important feature of pervasive applications
Contexts locations, time etc. Implicit input/output Seamless integrated Contextawareness Sense environment automatically Remember history Adapt to changing situations
Context-aw ar eness Application An example
Supply Chain Scenar io The example used in the paper
Reading RFID tags
Update warehouse database
Context-aw ar eness Resolution An example of application semantics
Contexts locations, time etc. Implicit input/output Seamless integrated
Context I nconsistency •
Reasons – Environmental noise
•
Examples – RFID reader report wrong readings • Register incorrect number in warehouse – GPS or GSM devices report inaccurate location • Pick wrong route
Context I nconsistency Resolution Consistency constraints
Context queue
Validate consistency constraints
Inconsistency resolution
2) Remove oldest 3) Remove all 4) User preference, heuristics etc.
Inconsistent contexts
1) Remove latest
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Context I nconsistency Resolution L imitation • Difficult to identify problematic contexts – E.g., remove the latest, oldest, least frequently used etc. – Counter example to remove the latest • Two RFID readers, the first one is inaccurate, the second one is accurate
• Resolution approaches rely heavily on constraints – Accuracy and completeness of constraints are crucial – Counter example • Constraint: Two RFID readers report identical readings • Reported readings are the same but inaccurate
Resear ch Pr oblem
How to get a better Context Inconsistency Resolution for Context-aware Services
T heir Pr oposal : H ybr id Solution The big picture
Example of the pr oposal 1. Two readers report inconsistent readings
2. Postpone inconsistency resolution 3. Warehouse check in, collect weight info
4. Update profile of goods 5. Resolve inconsistent readings based on weight and profile Chen, Ye and Jacobsen, PerCom'11, Seattle
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Challenges H ow to mak e use of the application semantics in r esolution?
Close to T 0: Semantic infor mation is of limited usefulness
Close to T 2: When to unacceptable r esolve? r ecover y cost
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Example of Application Semantics • Previous Location: (2, 3) • Current Location: (4, 5) • Inconsistency found! • The probability of each context being inaccurate is 50% warehouse
• Continue move one step • New Location: (4, 4)
• (2, 3) is more likely to be inaccurate, since it is impossible to move from (2, 3) to (4, 4) in two steps. Chen, Ye and Jacobsen, PerCom'11, Seattle
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Context-cor r elation M odel
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Application Er r or Recover y Inconsistency detection
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Backward recovery Forward recovery
Example of Er r or Recover y
• Backward recovery – Backtrack the movement
• Forward recovery – Select a different path warehouse
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COST M OD EL
• Compensation cost (cpc) – For backward recovery – Cost of compensating a task
• Execution cost (ecc) – For forward recovery – Cost of executing a task
• Total cost for an error recovery plan
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Resolution Algor ithm
Resolution Algor ithm Inconsistency detected
Resolve inconsistency
Postpone resolution
Compute error recovery cost
Application continues
Collect application semantics
Calculate probability
Build correlation graph
Error recovery
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Exper iment XXXXXX
Exper iment Setup
• 16 X 16 Map • cpc = ecc = 1 • Search the target in a heuristic way • Random placement of goods • Metrics: – Accuracy of resolution – Cost of error recovery Chen, Ye and Jacobsen, PerCom'11, Seattle
warehouse
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Results L-RL: Remove latest L-RO: Remove oldest M-H: Hybrid solution
Higher error rate
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Results L-RL: Remove latest L-RO: Remove oldest M-H: Hybrid solution
Location-aware Higher threshold Chen, Ye and Jacobsen, PerCom'11, Seattle
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Results L-RL: Remove latest L-RO: Remove oldest M-H: Hybrid solution H-ER: Error recovery only
Higher error rate
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Results L-RL: Remove latest L-RO: Remove oldest M-H: Hybrid solution H-ER: Error recovery only
Location-aware Higher threshold Chen, Ye and Jacobsen, PerCom'11, Seattle
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Scalability Randomly generate correlation graph Calculate probability of each context being inaccurate Record the time needed
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Some T houghts & Refer ences RF I D & D iscussion
Concluding r emar k s
• A novel approach to resolve context inconsistency – Combine low-level inconsistency resolution with high-level error recovery – Correlation model to reason about inaccurate contexts – Cost model to calculate recovery cost – Algorithm to trade off accuracy against recovery cost
• Future work – More real-life experiments
Society’s Concer ns Privacy
Tracking individuals Illicit or inappropriate use of personal data Tracking personal activities (e.g., purchase habits, travel)
Security
Unsanctioned readers Theft of information Inadequate encryption
Global differences
Regulations around collecting data Standards Ownership of data
Back U p Slides & Refer ences RF I D & D iscussion
Back U p Slide RF I D T ags: Passive vs. Active
Benefits of RF I D •Automatic reads •Active chips can be written •Many chips can be read simultaneously •Standardized and unique encoding •Better process specific data collection
I nnovative Applications SUPPLY CHAIN TRACKING RETAIL AND INVENTORY MANAGEMENT BAGGAGE HANDLING CREDIT CARDS HEALTH CARE ID AND MEDICAL DATA SMART PASSPORTS IMPORT/EXPORT PROCESSES AUTO ID FOR TOLLS, IGNITION, PARKING CHILD AND PET TRACKING
Refer ence Books RFID security Rockland, MA : Syngress, c2006 Frank Thornton ... [et al.]. RFID implementation New York : McGraw-Hill, c2007. Dennis E. Brown. RFID essentials Beijing ; Sebastopol, CA : O'Reilly, 2006 Bill Glover and Himanshu Bhatt. RFID for dummies Hoboken, N.J. ; Chichester : Wiley, 2005. by Patrick J. Sweeney.
Websites Managing RFID data http://portal.acm.org/citation.cfm?id=1316791 http://portal.acm.org/citation.cfm?id=1083592.1083723 http://www.informaworld.com/index/768428270.pdf http://portal.acm.org/citation.cfm?id=1107548.1107603 http://www.ingentaconnect.com/content/mcb/089/2003/00000031/00000010/art00005 Temporal management of RFID data http://portal.acm.org/citation.cfm?id=1083592.1083723 http://www.springerlink.com/index/f32p7n6t32q71703.pdf http://portal.acm.org/citation.cfm?id=1164127.1164143 http://millennium.cs.ucla.edu/~zaniolo/papers/ICDE07RFID.pdf http://www.itee.uq.edu.au/~xueli/RoozbehDerakhshan.pdf Mining compressed commodity workflows from massive RFID data sets http://portal.acm.org/citation.cfm?id=1183641 http://daisy.cs.uiuc.edu/hector/research.pdf http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4368141 http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4401085 http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4529801 Warehousing and Analyzing Massive RFID Data Sets http://xavier.ceng.calpoly.edu/ime312/RFID_warehouse.pdf http://portal.acm.org/citation.cfm?id=1083592.1083723 http://doi.ieeecomputersociety.org/10.1109/ICDE.2006.171 http://www.springerlink.com/index/r7y7wnmwqtfpx92t.pdf http://portal.acm.org/citation.cfm?id=1080148.1080164
Context-cor r elation M odel
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RF I D in Action
A Ver y Active T ag
Back U p Slide
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the Guard channel policy rejects all new calls until the channel occupancy goes below threshold
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Some Other T houghts Sky is still the limit but RFID did not reached half of its limit yet Some L ink s (if time permits)
RFID - Technology Video (Detailed) http://www.youtube.com/watch?v=4Zj7txoDxbE RFID Demonstration http://www.youtube.com/watch?v=FVmD4iTXRLE That´s how we will shop within a couple of years! http://www.youtube.com/watch?v=sDyqhcy1L-0 Future Store (Smart Check Out) http://www.youtube.com/watch?v=zBz3aoikLpU
F U n T houghts & food for thoughts
F U N T houghts or F ood for thought How can we redesign this earth from fresh? What will be the goal? What kind of systems we need to establish?
Some L ink s (if time permits)
Redesigning the human civilization (Detailed) http://www.youtube.com/watch? v=eK2KBFjShVs&annotation_id=annotation_25083&sr c_vid=uOw5eW52vRk&feature=iv Resource based economy http://www.youtube.com/watch? v=uOw5eW52vRk&feature=mfu_in_order&list=UL