Understanding RFID COUNTING PROTOCOL

Review & PResentation

Understanding RFID Counting Protocols Binbin Chen# Ziling Zhou^# Haifeng Yu^ # Advanced Digital Sciences Center ^ National University of Singapore MOBICOM 13

Antenna IC Chip Substrate Connection

outline

RFID & Discussion on Papers

outline Background ~ RFID Introduction ~ Counting Protocols & Counting Research Research problem & the big picture ~ Three Questions Detailed Discussion ~ Which design aspects are important ~ The two phases ~ Validating their thesis Experimental Results from the better protocol Concluding Remarks References and Fun Thoughts

intRoductoRy woRds: “ A Needed 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

RFid: what is it ?

RFID combines many of the features of several of these technologies ●

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– 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.

examPle: RFid in libRaRies

Simplifies checkout process for staff

Inventory of Collections

Use with new and future technology

Item Security

Express checkout for patrons

cuRRent technology

Middle ware

 Manage, collect, filter, aggregate and maintain for application.  Keep track of underlying sensors  Context aware application can adapt behavior with support of mw.

how is RFid 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

many aPPlications need counting

RFID technology enables large-scale counting

maRket & aPPlication Industrial Products

Logistics/ Trans.

Consumer Products

Retail Products

Homeland Security

Key Industry Drivers Leading Us Toward RFID

Other Service

RFid counting PRoblem (a simple single-set version)

• One reader and tags • They run a protocol to get an – Getting the exact is expensive Randomization helps • Guarantee: holds (say, with probability) – Here, bounds the relative error

See paper for generalizations: Measure of Goodness or Performance = Amount of time is needed (slot used) e.g., a reader moves around to extend coverage

Monte Carlo Randomized Algo Time slot & Predicate Function

Legends: RFID tag RFID reader

ReseaRch PRoblem

ReseaRch PRoblem

(Three main questions)

Question 1: Given the long list of protocols in practice, how much room is there for further improvement?

Question 2: What are the key aspects that determine a RFID counting protocol’s performance? What are the techniques that are only of secondary importance?

Question 3: Guided by the answers to the earlier two questions, can we easily design simple protocols that outperform existing ones?

ReseaRch PRoblem

(Three main questions)

Question 1: Given the long list of protocols in practice, how much room is there for further improvement?

Answer 1: To determine how much improvement is still possible, we obtain strong lower bounds on the overhead of RFID counting, by leveraging a recent breakthrough result on communication complexity [GHD Paper by Chakrabarti & Regev, 11].

ReseaRch PRoblem

(Three main questions)

Question 2: What are the key aspects that determine a RFID counting protocol’s performance? What are the techniques that are only of secondary importance?

Answer 2: They identify that a key design aspect for singleset RFID counting protocols to approach optimal performance is to have two conceptual phases: The first phase uses roughly Θ(log log n) slots to obtain a rough estimate with constant (e.g., 0.5) relative error, and the second phase uses roughly ( 1/ (ε2 .log 1/ ε)) slots to eventually obtain a final estimate with the desired relative error of ε.

ReseaRch PRoblem

(Three main questions)

Question 2: What are the key aspects that determine a RFID counting protocol’s performance? What are the techniques that are only of secondary importance?

Answer 2 (cont.): Also their thesis further indicates that many other performance-enhancing or ideas techniques (Seven of the current research) proposed in the literature are only of secondary importance.

ReseaRch PRoblem

(Three main questions)

Question 3: Guided by the answers to the earlier two questions, can we easily design simple protocols that outperform existing ones?

Answer 3: They manage to design such protocols by simply putting together a few basic building blocks from the literature. Although they do not claim novelty on these building blocks – instead, they aim to show that simply putting them together in a proper manner as guided by their earlier answers is already sufficient to outperform existing protocols. This serves as an ultimate validation of the utility of our earlier findings.

design asPect

RFid counting PRoblem

• One reader and tags • They run a protocol to get an – Getting the exact is expensive Randomization helps • Guarantee: holds (say, with probability) – Here, bounds the relative error See paper for generalizations: e.g., a reader moves around to extend coverage

Legends: RFID tag RFID reader

existing RFid counting ReseaRch

• An impressive arsenal of techniques

existing RFid counting ReseaRch

• An impressive arsenal of techniques

• The central design goal: Reduce time overhead & provide the guarantee

• Diverse views on which design aspects are important Should we combine all these techniques despite the resulting complexity?

Novel statistical gauges Optimization of parameters Adaptive iterations ……

theiR centRal thesis FoR RFid counting

The overlooked key is to have two phases:

1st phase

Rough estimate

2nd phase

Final estimate

Other techniques proposed in the literature are less important than originally thought Note: • the term can be reduced to a term

the insPiRation • Novel lower boundsfor RFID counting protocols: (Rough) Theorem: For single-set RFID counting, no protocol can estimate with relative error while incurringoverhead

• Our proof leverages a recent breakthrough result in communication complexity [Chakrabarti&Regev, STOC’11] – They proved GHD (Gap Hamming Distance) problem is hard – We connect RFID counting and GHD by a novel reduction – Details in paper

two distinct gRouPs Multiplicative overhead:

Enhanced

Additive overhead:

Note: • Some protocols reduce the term to a term

dditive-oveRhead PRotocols aRe betteR

Enhanced

Additive overhead:

ow they achieve additive oveRhead? • Despite their many differences (as originally emphasized), they all have a two-phase design:

1st phase

Rough estimate

2nd phase

Final estimate

theiR thesis has not been discoveRed

Enhanced Use of a novel gauge: the indices of the first non-empty slots

FNEB (’10) ART (’12) Use of a novel gauge: the average run length of non-empty slots

ZOE (’13) i) Unique design about the gauge: trial has a single They also employ other Each interesting techniques: slot

– involved optimizations, adaptive iterations …

ii) Two-phase design

an old gauge oF the eaRly eZb (’07) PRotocol

• # of empty slots

– More empty slots less tags

1

2

3

4

5

6

the novel gauges • ART: average run length of non-empty slots – In the example: (1+2+1)/3 • FNEB: index of the first non-empty slot • ZOE: still # of empty slots, but each slot is independent

1

2

3

4

5

6

let us examine aRt’s (’12) PeRFoRmance gain (over the early EZB (’07) protocol)

RePlace aRt’s (’12) gauge by the old eZb’s (’07) gauge We keep everything else unmodified

similaRly …

• FNEB’s gauge seems not help

• Neither does ZOE’s

a new(?) design &exPeRiment

• The design of is solely driven by our thesis: – It applies the 2-phase design – It uses simple & basic building blocks in all other aspects we claim no novelty for these building blocks

pseudo-code: 1: Invoke a simple early protocol (LOF ’08) to get a rough estimate ; 2.1: calculate tag-responding probability according to ; 2.2: Use a simple early gauge (EZB ’07) to obtain the final estimate;

is faster

how about multiPle-set RFid counting?

• Consider a reader sequentially visits multiple locations to count # of tags in a large space – Here : the sets can overlap

aPPly theiR thesis •• Unlike single-set case, no one happens to use 2 phase – All existing protocols incur multiplicative overhead – Our thesis hints that big improvement might be possible

• Applying our thesis needs to overcome a challenge – The reader has no rough estimate of until the last location

• Our protocol uses some interesting techniques to overcome the challenge – It achieves additive overhead, and is faster

• Knowing the thesis is critical – It guides us to identify & focus on the key challenge

concluding RemaRks

• Inspired by RFID counting lower bound results, as they find the overlooked key is a 2-phase design

1st phase

Rough estimate

2nd phase

Final estimate

• All other techniques are less important • Future work – Non-progammable RFID

back uP slides & ReFeRences RFID & Discussion

society’s conceRns 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 uP slide RFid tags: Passive vs. active

beneFits oF RFid • Automatic reads • Active chips can be written • Many chips can be read simultaneously • Standardized and unique encoding • Better process specific data collection

innovative 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

ReFeRence 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.

Papers

1874Randomzied Algorithms - Motwani, Raghavan – 1995 359Probabilistic computations: towards a unified measure of complexity - Yao – 1977 340Probabilistic counting algorithms for data base applications - Flajolet, Martin – 1985 92A linear-time probabilistic counting algorithm for database applications - Whang, Vander-zanden, et al. – 1990 50Analysis of tree algorithms for RFID arbitration - Hush, Wood – 1998 30Evaluating and optimizing power consumption of anti-collision protocols for applications - Zhou, Chen, et al.

26An optimal algorithm for the distinct elements problem - Kane, Nelson, et al. – 2010 26Fast and reliable estimation schemes in rfid systems - Kodialam, Nandagopal – 2006 19Cardinality estimation for large-scale RFID systems - Qian, Ngan, et al. – 2008 12Anonymous tracking using RFID tags - Kodialam, Nandgopal, et al. – 2007 12Framed ALOHA for multiple RFID objects identification - Zhen, Kobayashi, et al. – 2005 11Finding popular categories for RFID tags - Sheng, Tan, et al. – 2008 7An Optimal Lower Bound on the Communication Complexity of Gap Hamming CHAKRABARTI, REGEV 6Counting RFID tags efficiently and anonymously - Han, Sheng, et al. – 2010 62010a) ‘Energy efficient algorithms for the RFID estimation problem - Li, Wu, et al.

4PET: Probabilistic estimating tree for large-scale RFID estimation - Zheng, Li – 2012 2Efficient and reliable low-power backscatter networks - Wang, Hassanieh, et al.

1Understanding RFID counting protocols. Technical report. Available at http://www.comp.nus.edu.sg/~yuhf/rfid-tr.pdf - Chen, Zhou, et al.

1RFID as an Infrastructure - Qiao, Chen, et al. – 2013 1Every bit counts - fast and scalable RFID estimation - Shahzad, Liu – 20121 ZOE: Fast cardinality estimation for largescale rfid systems - Zheng, Li - 2013

Fun thoughts & Food FoR thoughts

Fun thoughts oR Food FoR thought WHAT ELSE WE CAN DO WITH HUMAN INTERACTED RFID WHAT IS GOOGLE TANGO WHAT PRICE SHOULD WE HAVE FOR A 3D PRINTER