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RFID-based Distributed Memory for Mobile Applications. Michel Simatic. Table of contents. Introduction Passive RFID tags in existing architectures RFID-based distributed memory Experimental results Issues Conclusion and future work. Table of contents. Introduction
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RFID-based Distributed Memory for Mobile Applications Michel Simatic
Table of contents • Introduction • Passive RFID tags in existing architectures • RFID-based distributed memory • Experimental results • Issues • Conclusion and future work RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Table of contents • Introduction • Passive RFID tags in existing architectures • RFID-based distributed memory • Experimental results • Issues • Conclusion and future work RFID-based Distributed Memory for Mobile Applications – 15/10/2009
IntroductionRFID overview • RFID tag = Memory + Antenna + (radio) communication capabilities • Memory contains • (always) A unique identifier • (possibly) Bytes which can be written (and read ;-) ) • Tags can be passive or active • NFC technology can be used to interact with nearby tags • By 2013, 700 million users will have an NFC-enabled mobilephone [NFC study, 2008] • An RFID tag “contains” also applicative data: An RFID tag “stores” applicative data (located in the tag or elsewhere) related to the physical entity (object, person, location…) which the tag is linked to RFID-based Distributed Memory for Mobile Applications – 15/10/2009
IntroductionClassical RFID-based architectural pattern • Centralized architectural pattern [GS1 EPCglobal, 2007] RFID-based Distributed Memory for Mobile Applications – 15/10/2009
IntroductionClassical RFID-based architectural pattern Write DEF 2: Request to write DEF on tag r1 1: Read tag Id RFID-based Distributed Memory for Mobile Applications – 15/10/2009
IntroductionClassical RFID-based architectural pattern Read tag 2: Request value of tag r2 1: Read tag Id Request value of tag r2 Query tag r2 RFID-based Distributed Memory for Mobile Applications – 15/10/2009
IntroductionClassical RFID-based architectural pattern • Problem with centralized architectural pattern:It requires an access to a global network • LAN (Local Area Network)The mobile device must be connected via a cable or Bluetooth to an entity connected to a LAN • WLAN (Wireless Local Area Network)The mobile must have Wi-Fi capabilities+ The area must be covered by Wi-Fi • WAN (Wireless Area Network)The mobile must have access to a data plan allowing GPRS, UMTS or HSDPA connections RFID-based Distributed Memory for Mobile Applications – 15/10/2009
IntroductionGoal of this study • A global network is not available for some RFID-based applications • Find an RFID-based architectural pattern which meets the following requirements • Use of passive tags • No use of a global network (LAN, WLAN or WAN) • When users equipped with an RFID-enabled device read a tag, the applicative contents which is read is correct (no staleness issue) • Users equipped with an RFID-enabled device can query about the applicative contents of any remote tag (no need to be physically near the tag) RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Table of contents • Introduction • Passive RFID tags in existing architectures • RFID-based distributed memory • Experimental results • Issues • Conclusion and future work RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Passive RFID tags in existing architectures Centralized architectural pattern • How does it meet the requirements? • No use of a global network • When users equipped with an RFID-enabled device read a tag, the applicative contents which is read is correct (no staleness issue) • Users equipped with an RFID-enabled device can query about the applicative contents of any remote tag (no need to be physically near the tag) RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Passive RFID tags in existing architectures Semi-distributed architectural pattern • Pattern used in the application used to take care of Paris trees [Paris trees, 2006] RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Passive RFID tags in existing architectures Semi-distributed architectural pattern Sync Sync Sync Sync Sync Sync RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Passive RFID tags in existing architecturesSemi-distributed architectural pattern Write DEF 2: Write DEF 1: Read tag Id RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Passive RFID tags in existing architecturesSemi-distributed architectural pattern Read tag 2: Read contents 1: Read tag Id Read contents Query tag r2 RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Passive RFID tags in existing architecturesSemi-distributed architectural pattern 1: Read tag Id Read tag Read contents ?????? Read tag 1: Read tag Id Read contents RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Passive RFID tags in existing architecturesSemi-distributed architectural pattern Sync Sync Sync Sync Sync Sync RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Passive RFID tags in existing architecturesSemi-distributed architectural pattern • How does it meet the requirements? • No use of a global network • When users equipped with an RFID-enabled device read a tag, the applicative contents which is read is correct (no staleness issue) • Users equipped with an RFID-enabled device can query about the applicative contents of any remote tag (no need to be physically near the tag) RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Passive RFID tags in existing architecturesDistributed architectural pattern • The Ubiquitous Near-Field Distributed Memory [Couderc and Banâtre, 2009] RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Passive RFID tags in existing architecturesDistributed architectural pattern Write DEF Write DEF RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Passive RFID tags in existing architecturesDistributed architectural pattern Read tag Read contents ??????????? Query tag r2 RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Passive RFID tags in existing architecturesDistributed architectural pattern • How does it meet the requirements? • No use of a global network • When users equipped with an RFID-enabled device read a tag, the applicative contents which is read is correct (no staleness issue) • Users equipped with an RFID-enabled device can query about the applicative contents of any remote tag (no need to be physically near the tag) RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Table of contents • Introduction • Passive RFID tags in existing architectures • RFID-based distributed memory • Experimental results • Issues • Conclusion and future work RFID-based Distributed Memory for Mobile Applications – 15/10/2009
RFID-based Distributed Memory • Mixing Semi-Distributed and Distributed architectural patterns RFID-based Distributed Memory for Mobile Applications – 15/10/2009
RFID-based Distributed Memory Write DEF 1: Read contents 2: Write DEF and 42 (41+1) RFID-based Distributed Memory for Mobile Applications – 15/10/2009
RFID-based Distributed Memory Read tag 1: Read contents 2: Write contents Query tag r2 RFID-based Distributed Memory for Mobile Applications – 15/10/2009
RFID-based Distributed Memory 1: Read 2: Write Read tag Read tag 1: Read 2: Write RFID-based Distributed Memory for Mobile Applications – 15/10/2009
RFID-based Distributed Memory • How does it meet the requirements? • No use of a global network • When users equipped with an RFID-enabled device read a tag, the applicative contents which is read is correct (no staleness issue) • Users equipped with an RFID-enabled device can query about the applicative contents of any remote tag (no need to be physically near the tag) RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Table of contents • Introduction • Passive RFID tags in existing architectures • RFID-based distributed memory • Experimental results • Issues • Conclusion and future work RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Experimental resultsPervasive game as an application example • « Plug : Secrets of the museum » = a pervasive game played inMusée des arts et métiers [Plug, 2009] • 12 game sessions / 150 players15 game sessions / 200 players • 16 RFID tags are linked to specific objects. Each tag hosts a virtual card • Players are equipped with NFC-enabled mobile phones. Each phone hosts4 virtual cards • Players have to collect virtual cards of the same family.To do so, players exchange virtual cards with tags or with other players • No global network • Nokia 6131 NFC is not Wi-Fi enabled (+ the museum is not covered with Wi-Fi) • UMTS data plans are too expensive • The distributed architectural pattern could fit, but… RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Experimental resultsPervasive game as an application example • … but the game design requires a “hint function” • To help players collecting their family of cards, players can ask their mobile for a hintTwo possible answers: • 2 minutes ago, card “Lavoisier” was on tag “Statue of Liberty” • A priori, no tag contains an object which is of interest for you • To compute this answer, the mobile must query the contents of all of the tags, including the remote ones. RFID-based Distributed Memory • DMe[r] is a byte containing the value of the virtual card hold by tag rVCe[r] is a short containing the vector clock value RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Experimental results • 5 sessions (with 6 players each) were analyzed to evaluate RFID-based Distributed Memory • 88% of the hints were correct • Correctness depends of • How many tags are notified of a change • How long it takes to disseminate such information RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Experimental results • To evaluate dissemination of stale information, we define the notion of validity period • Validity period = Time of the next change of tag r – Time at which information concerning tag r contents is written Tag r3 Write MNO Tag r1 contains DEF Tag r2 contains UVW Tag r2 Write RST Tag r1 contains GHI Write UVW Tag r1 contains DEF Tag r1 Write DEF Write GHI Blue mobile Orangemobile Time Validity period of r1 info = t3 – t4 < 0 Stale information Validity period of r2 info = t5 – t4 > 0 Up-to-date information t1 t2 t3 t4 t5 RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Experimental results %) • Frequency of validity periods RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Table of contents • Introduction • Passive RFID tags in existing architectures • RFID-based distributed memory • Experimental results • Issues • Conclusion and future work RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Issues • Staleness • Experimental results • 100 – 88 = 12% of hint are not correct • 5% of data remained stale more than 12 minutes • How to reduce the problem? • A dedicated user goes periodically through all of the tags • We ask all users to periodically meet all together to synchronize their DMmobile • We relax the constraints concerning the global network.Thus, we introduce a server.Periodically, each phone synchronizes DMmobile and DMserver • Scalability • Hardware has limited size • It takes time to read DMr and VCr, and to write them back • For “Plug: Secrets of the museum”, limit is min(341,1104) = 341 tags RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Table of contents • Introduction • Passive RFID tags in existing architectures • RFID-based distributed memory • Experimental results • Issues • Conclusion and future work RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Conclusion • RFID-based Distributed Memory meets the requirements • No use of a global network (LAN, WLAN, WAN) • When users equipped with an RFID-enabled device read a tag, the applicative contents which is read is correct (no staleness issue) • Users equipped with an RFID-enabled device can query about the applicative contents of any remote tag (no need to be physically near the tag) • It is an interesting alternative to existing architectural patterns • Integrate in DM data linked to other entities of thesystem (e.g. mobile devices). See demo. • RFID-based Distributed Memory can be considered as an implementation of opportunistic data flooding [Zebranet, 2002].Our contribution is to integrate passive RFID tags in such peer-to-peer architecture RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Future work • Tackle issues • Staleness • Scalability • RFID-based Distributed Memory works because three conditions are verified • An element of DM can only be modified in one place • The set of RFID tags contributing to DM is defined at the beginning of the system lifetime • The set of RFID tags is ordered Release one (or more) of the three conditions • Model this Distributed Memory to determine the conditions on the number of mobiles, the behavior of the mobile users, the number of tags, the distance between the tags… which turns this Distributed Memory into a useful architecture RFID-based Distributed Memory for Mobile Applications – 15/10/2009
Thank you for your attention • Questions ? RFID-based Distributed Memory for Mobile Applications – 15/10/2009
References • [Couderc and Banâtre, 2009] P. Couderc and M. Banâtre. Beyond RFID: The Ubiquitous Near-Field Distributed Memory. ERCIM news, (76):35–36, January 2009. • [GS1 EPCglobal, 2007] F. Armenio, H. Barthel, L. Burstein, P. Dietrich, J. Duker, J. Garrett, B. Hogan, O. Ryaboy, S. Sarma, J. Schmidt, K. Suen, K. Traub, and J. Williams. The EPCglobal architecture framework. Technical Report Version 1.2, GS1 EPCglobal, September 2007. • [NFC study, 2008] Christian D. 700 million of users of NFC mobiles in 5 years (in French). http://www.generation-nt.com/juniper-etude-technologie-nfc-mobile-utilisateurs-actualite-151831.html, September 2008. • [Paris trees, 2006] ITR Manager.com. City of Paris is taking care of its trees with RFID tags (in French). http://www.itrmanager.com/articles/59758/59758.html, December 2006. • [Plug, 2009] M. Simatic, I. Astic, C. Aunis, A. Gentes, A. Guyot-Mbodji, C. Jutant, and E. Zaza. “Plug: Secrets of the Museum”: A pervasive game taking place in a museum. In Entertainment Computing - ICEC 2009, Eighth International Conference, Paris, France, September 3-5, 2009, Proceedings, Lecture Notes in Computer Science. Springer, September 2009. • [Zebranet, 2002] P. Juang, H. Oki, Y. Wang, M. Martonosi, L. S. Peh, and D. Rubenstein. Energy-efficient computing for wildlife tracking: design tradeoffs and early experiences with zebranet. In ASPLOS-X: Proceedings of the 10th international conference on Architectural support for programming languages and operating systems, pages 96–107, New York, NY, USA, 2002. ACM. RFID-based Distributed Memory for Mobile Applications – 15/10/2009