Challenges to data carrier in networked RFID

Transcription

1 Challenges to data carrier in networked RFID Feb. 21, 2008 Jin MITSUGI Associate Professor, Keio University Associate Director, Auto-ID Laboratory Japan

2 Defining Networked RFID EPCglobal network EPCglobal core services Subscriber EPCIS AuthenticationDiscovery ONS Root Tag Mngr Data Num Assignment Schema ISO/IEC EPCglobal subscriber EPC IS Accessing application EPCIS Query Interface EPC IS Repository EPC IS Capturing application ALE Interface Local ONS EPCIS Capturing Interface Partner EPCglobal subscriber EPC IS ONS Accessing application HW/SW Role Interface Filtering & Collection Reader Interface Reader Reader Management Reader Management Air Protocol TDS RF Tag Page 2

3 Data carrier in networked RFID (1) Conventional seal An RFID equipped smart seal for container security ID + Tamper information Jerry Banks, David Hanny, Manuel Pachano, Les Thompson, RFID APPLIED, Wiley, (2007), pp Page 3

4 Data carrier in networked RFID (2) Life cycle information management of Consumer electronics Recycle Manufacturer Consumer ID + Maintenance record ID + Lot number/ Hazardous Substance info Logistics Retailer ID + Sales Record Page 4

5 Data carrier in networked RFID (3) cold chain management ID + Sensor Data R.Kasper, The Cold Chain for perishable products in the air freight, Page 5

6 Data carrier in networked RFID (4) Suppliers Integrator Operator Maintenance Repair & Overhaul (MRO) manufacture to delivery Page 6 service life ~ 1-3 years up to 30 years

7 Related standards (incl. Working Draft) Application ObjectId or physical address specified Objectdata readsingleobject Filter & Collection Logical Memory ObjectId + ObjectData Physical address specified C1G2OpSpec:C1G2ReadParameter Raw data Interrogator ALE ISO 15961/15962 LLRP Physical address specified Read Tag EPC User Specific Data Raw data Gen2 ISO Rev1 (WD) ISO 24753(WD) IEEE 1451 Page 7

8 Fundamental challenges for data carrier in networked RFID Application ObjectId or physical address specified Objectdata readsingleobject Filter & Collection Logical Memory ObjectId + ObjectData Physical address specified C1G2OpSpec:C1G2ReadParameter Raw data Interrogator How do we map ObjectId with physical memory address in tags? Physical address specified Read Tag EPC User Specific Data Raw data How do we efficiently transfer data between reader and tags? Page 8

9 Data synchronization Page 9

10 How do we map ObjectId with physical memory address in tags? (1) Store the ObjectId and Data pair in the tag memory readallobjectids Tag Logical Memory ObjectId ObjectId Data Data catalogue of ObjectIds Pros. Cons. Catalogue of ObjectId can be built by reading all objectid. ISO non-directory access method Tag Physical Memory TID Memory bank Pointer to sensor address map (PSAM) USER Memory bank Data address, data length ObjectId, data Page 10 ISO WD reference reference Building the catalogue of ObjectId may be time consuming. User memory consumption may be large. ObjectId in tag may be further translated to comprehensive objectid. Canonicalization of increasing objectids.

11 How do we map ObjectId with physical memory address in tags? (2) Application ObjectId or physical address specified readsingleobject Filter & Collection Logical Memory ObjectId + ObjectData Objectdata Physical address specified C1G2OpSpec:C1G2ReadParameter Raw data Interrogator EPC Memory schema ObjectId Memory schema Resolver Physical address Physical address specified Read Tag Raw data ObjectId ObjectId Physical address Physical address EPC Page 11 User Specific Data

12 Building catalogue of ObjectId Speed comparison experiment Experiment description Time for the existing method is estimated by the measured turnaround time of a commercial reader Forward link=return link=40kbps Memory registry is in the same subnet of F&C. Catalogue building time msec Existing Proposal Number of ObjectIds to be retrieved from tag Proposed method can be advantageous in large number of ObjectIds cases. Page 12

13 How do we efficiently transfer data between reader and tags? Retrieving user-specific data under noisy environment (an experiment) Time to retrieve user-specific data msec 70 CNR=22dB CNR=25dB Noise free Block read unit (word) Forward link=return link=40kbps Even slightest noise deteriorates the user-specific data retrieval from tags. Page 13

14 Adaptive Block Size Control mechanism The first step: Similar to slow start in TCP The required time to be read (msec) Fixed block size (words) Retransmission entails longer reading time = Maximum block size with no retransmission Page 14

15 Adaptive block size control Experiment 300 The Required required time time to be to read be (msec) read Block size Size (words) (Word) SNR: 23dB SNR: 26dB Page 15

16 Protocol overhead is large R/W 1 st block 2 nd block fail L (words) large length tag data X th block 3 rd block Select Query ACK reqrn Read l (words) X th block TAG RN16 EPC Overhead handle User-specific data Reading user data A set of packet series for one block reading Page 16

17 Simulation including the practical protocol overhead The required Required time time to be read to be (msec) read 1.400E E E E E E E E+00 BER=1.00E-4 BER=1.00E-5 BER=1.00E-6 BER=1.00E Block Size size (words) (Word) 60words Data Small block size suffers from the degradation of reading speed due to large overhead Page 17

18 mechanism large length tag data 1 st block reading fail 1 st block repeat 2 nd block reading fail 2 nd block repeat fail 3 rd block repeat Success Success 4 th block repeat Adaptive block size optimization fail Page 18

19 Summary Generalized handling of user-specific data in tags entails a number of research topics. Memory schema resolver Large data retrieval Data synchronization Page 19