EPC Network - Industrial Applications of RFID...

GQ Huang

RFID-Basics-1

The University of Hong Konghttp://www.digiprise.org/ielm6050/ RFID-Basics-1

Components of RFID Systems

� RFID Principles� Hardware Components

� Software Components

� Infrastructure (EPCglobal) Network


How does RFID work?


Hardware Components of RFID Systems

� Basic Hardware Components� Basic RFID Principles

� RFID Tags

� RFID Readers� Host Computers

The University of Hong Kong http://www.digiprise.org/ielm6050/RFID-Basics-4

EPC Network – Building Blocks

Tags Data carrier – the ID number – Unique EPC Code – is programmed into the Tag

Tag Antenna

Connected to chip in Tag – could be wire or printed using conductive ink

Reader Antenna

Coil included in plastic or similar case – usually 12 – 18 inches square

Reader Data capture device – interrogates the tag and retrieves the data from all tags in the receiving area. Can be fixed or portable

GQ Huang

RFID-Basics-2


EPC Network – Building Blocks

Tags Data carrier – the ID number – Unique EPC Code – is programmed into the Tag

Tag Antenna Connected to chip in Tag – could be wire or printed using conductive ink

Reader Antenna

Coil included in plastic or similar case – usually 12 – 18 inches square

Reader Data capture device – interrogates the tag and retrieves the data from all tags in the receiving area. Can be fixed or portable

Savant Servers/Software to support readers, extract unique information from the read data, and communicate with External databases

ONS Object Name Service – similar to DNS in the Internet – knows the appropriate database holding full information about the product the tag is attached to


RFID Tags

� Paper thin and approximately 2”x 2” (50mm x 50mm) in size

� Placed inconspicuously on the inside cover of each book in a library’s collection

� Consists of an etched antenna and a tiny chip which stores vital bibliographic data including a unique ID number to identify each item

� Compare this to a barcode label which does not store any information and only points to a database


RFID Reader & Antenna

� Wide range of shapes and sizes to suit respective applications within the library

� Reader powers the antenna to generate an RF field� When a tag passes through this RF field, the information stored

on the chip is decoded by the reader, and sent to the central server that in turn, communicates to the Library Information System


RFID readers and tags

Hand-held

Combobar code/RFID

Fixed

OutsideDesktop

RFID Readers

Passive Tags – No power

Active Tags – Power, more storage, sensors

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RFID-Basics-3


Key functions of RFID components

� RFID Tag comprised of a microchip (that stores the unique identification number) and tag antenna (that enables the microchip to transmit ID information)

� RFID Network Components (readers, antennas, cables) that power and communicate with tags, converting radio waves returned from the tags into computer-readable information

� System Management Software that runs on a host computer and collects tag data automatically from the reader network


Tag

Basic RFID Principles of Tag and Reader Communications

Reader /Antenna


RFIDTag

How does RF work?� Carry data in a suitable Tag and recover the information by a non-contact

Radio Frequency communication. � The Antenna generates an electromagnetic field that energizes a chip (IC-

circuit) inside the Tag.

� The electromagnetic field is modulated by the Tag.

� The modulated signal is recovered by the Antenna and sent to the Reader unit for interpretation.

Antenna

Reader


How does RF work?

GQ Huang

RFID-Basics-4


RFID Primer

Note: The RF module creates radio frequency (RF). It receivesand transmits RF through the antenna…

Reader

RF Module

Antenna

Host Computer


RFID Primer

Note: Tag (transponder) is interrogated by the antenna....

Reader

RF ModuleTag

Antenna

Host Computer


RFID Primer

Note: The antenna captures the tag ID number…first as analog RF waves, then it is converted to digital information.

(Tag ID Communication)

Reader

RF ModuleTag

Antenna

Host Computer


Passive RFID原理

1

Reader(Transceiver Antenna)

Tag(Transponder)

3

<135K / 13.56M / 433M / 868M / 915M / 2.45G / 5.8G

頻率頻率頻率頻率

晶片晶片晶片晶片

GQ Huang

RFID-Basics-5


Active RFID 原理 – Type 1

1

2

Reader(Transceiver Antenna)

Tag(Transponder)

3

<135K / 13.56M / 433M / 868M / 915M / 2.45G


晶片晶片晶片晶片電池電池電池電池

藉由電池能量

發射器與接收器


Active RFID 原理 – Type 2

1

2

Tag(Transponder)

3

<135K / 13.56M / 433M / 868M / 915M / 2.45G


晶片晶片晶片晶片電池電池電池電池

藉由電池能量

接收器

發射器

4 公尺左右

數十公尺


Operating Principles

� LF/HF RFID systems: Operating under the near-field condition of EM wave propagation based on the Inductive coupling principle.

� UHF/Microwave RFID systems: Operating under the Far-fieldcondition of EM wave propagation based on the Back-scattering principle.


LF/HF RFID Inductive coupling principle: Transformer

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RFID-Basics-6


UHF/Microwave Back-scattering principle: Radar detection

Reader to tag commands

- Change EM wave intensity

Tag to reader response

– Change reflection coefficients


RFID Tags

� Tags can be read-only or read-write� Tag memory can be factory or field programmed,

partitionable, and optionally permanently locked� Bytes left unlocked can be rewritten over

more than 100,000 times


An RFID tag is a portable database / mobile memory. A device used to transmit information such as a serial number to the reader in a contact less manner

…A sophisticated computing and communications device…A wireless extension of Information Systems

Interrogation UnitTx/RxMicro

Computer

Computer Network

Antenna Tag

Radio Tx/Rx

RAM ROM

CPU I/O

Pwr Supply

Radio Tx/Rx

RAM ROM

CPU I/O

Pwr Supply


Tag Attributes and Characteristics (TABLE 3.1)

Attribute Characteristics

Design � IC-Based � Most common tag. IC with memory to perform simple computations.

� Chipless � Relies on material properties of tag for data transmission. Can achieve higher range and better

accuracy. Does not have computational power or ability to store new/additional data.

Type � Passive –no battery. Reader power both memory and RF circuitry. � Offers lowest range and accuracy. Least costly.

� Active – battery power both RF circuitry and memory. � Offers highest range and accuracy. Costliest.

� Semi-Active – reader activate RF circuitry but battery powers memory. � Offers better range and accuracy than passive tags at lower cost than active tags.

Memory � Read Only � Data written at tag manufacture time makes tag tamper proof (native characteristic of chipless tags).

� Write Once/Read Many � Ability to write data one time only makes the tag tamper resistant but provides flexibility to write data

after tag manufacture time, which can significantly reduce production costs.

� Read/Write � Most flexible. Vulnerable to data tampering and overwrite.

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RFID-Basics-7


RFID Tag Attributes

Active RFID Passive RFID

Tag Power Source Internal to tag Energy transferred using RF from reader

Tag Battery Yes No

Availability of power Continuous Only in field of reader

Signal strength (reader to tag) Low High

Signal strength (tag to reader) High low

Range Up to 100m Up to 3-5m, usually less

Multi-tag reading 1000’s of tags recognized – up to 100mph

Few hundred within 3m of reader

Data Storage / Memory Up to 128Kb or read/write with sophisticated search and access

128 bytes of read/write

Applicability in supply chain Movement of tagged items is variable and unconstrained.

Movement of tagged items is constrained.


Passive RFID Tags

� “Traditional” tags used in retail security applications� Tag contains an antenna, and a small chip that

stores a small amount of data� Tag can be programmed at manufacture or on

installation� Tag is powered by the high power

electromagnetic field generated by the antennas –usually in doorways

� The field allows the chip/antenna to reflect back an extremely weak signal containing the data

� Collision Detection – recognition of multiple tags in the read range – is employed to separately read the individual tags

� These passive tags form the basis of the Auto-ID designs, and, if manufactured in billions, will come down in price from $0.80 to $0.05 in the next 2 years.


Active Tags

� Battery Powered tags

� Have much greater range – 100m

� Hold much more information – Kbytes

� Can integrate sensing technology

� Temperature, GPS

� Can signal at defined time

� Multiple tags can be recorded at once

� Used for higher value items

� Shipping containers

� Babies

� Electronic assets

� Cost between $20 and $40 per item� Life between 2 – 4 years


Types of Tags - Memory Segmentation

� Read Only (Factory Programmed)

� WORM - Write Once, Read Many times

� Reprogrammable (Field Programmable)

� Read/Write (In-Use Programmable)

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RFID-Basics-8


Effect of multiple tags in the read field

� If tags are very close to each other, the “shadowing” effect will de-tune the tag receiver and hence reduce the read range.

� Need to use “anti-collision” algorithm to distinguish individual tags:

� Binary search and eliminate algorithm


Effect of multiple readers in the same area

� For an enclosure that has multiple readers/antennas, certain area may be covered by more than one readers/antennas pair.

� Tags in those area may be confused as different readers are sending different commands at slightly different times.

� Need to sequence the readers and/or antennas so that they do not “illuminate” the same area at the same time.


LF/HF versus UHF Read-Distance comparison


HF Power versus Range

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RFID-Basics-9


Special behavior of UHF tags on metal plate


LF/HF versus UHF resistance to interference


RF penetration characteristics

� RF-lucent materials:� RF energy penetrate relatively easily

� Paper, plastics, cloth, cardboard

� RF-opaque materials

� Conductive materials (block or reflect energy)� Metal, metalized plastics/paper, some liquids, pastes

� Absorptive materials (weaken RF energy)� Most liquids and moist fibres.


How materials can affect read range

Material 2.45Ghz 13.56MHz

Paper OK OK

Cardboard OK OK

Cloth OK OK

Wood OK OK

Glass Detune Detune

Rubber Detune Detune

Plastics Detune Detune

Water / liquid film Block 65% of range

Water/liquid immersion Block 30% of range

Human body Block Detune

GQ Huang

RFID-Basics-10


Tags can be attached to almost anything

� pallets or cases of product� vehicles

� company assets or personnel

� items such as apparel, luggage, laundry� people, livestock, or pets

� high value electronics such as computers, TVs, camcorders


Chipless RFID Tags

� No IC chip inside, just special material that reflects RF signal back to reader

� Materials� Very small fibers (nano-resonant structures)

� An array of chemicals that reflects RF energy in a distinct manner.

� Tiny aluminum fiber.

� Operating principle

� Antennas are made of special materials randomly placed / printed on the surface.

� Its reflection of RF energy constitute a random number that can uniquely identify the object.


What is RFID? -- The Readers

� Readers (interrogators) can be at a fixed point such as

� Entrance/exit

� Point of sale

� Warehouse

� Readers can also be mobile --tethered, hand-held, or wireless


Functions of readers

� Energize the Tag� Define operating frequency

� Read data from the Tag

� Write data onto the Tag� Communicate with the host computer

� Conduct built-in processing

GQ Huang

RFID-Basics-11


Reader Implementation Challenges

� Reader must deliver enough power from RF field to power the tag

� Reader must discriminate backscatter modulation in presence of carrier at same frequency

� 70db magnitude difference between transmitted and received signals

� Interference between readers

� Hugh volume of tag data – readers need to filter data before releasing to enterprise network


RFID Basics 2 –RFID Reader & Antenna

� Wide range of shapes and sizes to suit respective applications within the library

� Reader powers the antenna to generate an RF field

� When a tag passes through this RF field, the information stored on the chip is decoded by the reader, and sent to the central server that in turn, communicates to the Library Information System


RFID Reader Management Requirements

� Taxonomy of Readers� Reader Requirements for:

� Configuration� Monitoring � Control

� Ongoing Reader Management Work


Fixed RFID Readers

� “Pizza box” readers with ~2-8 antennas� Typically used in supply chain applications

� Dock doors and conveyor belts

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RFID-Basics-12


Fixed Reader Systems

� Wide range of system capabilities� Similar to home gateway or wireless access point

� Processors:

� Low-end 16-bit to mid range (~266MHz) 32-bit processor plus DSP or FPGA for signal processing

� Operating Systems:� Proprietary, embedded, WinCE or Linux

� Networking:

� Stand-alone TCP/IP network nodes running DHCP, HTTP, Telnet (or SSH), NTP, SNMP and proprietary API and/or control protocol


Integrated Reader/Antenna

� Single antenna with integrated reader capability


Reader/Antenna Systems

� Wide range of system capabilities� Very low-end access control point to higher-end “smart antennas”

� Processors:

� DSP only to low-end 16-bit CPU

� Operating Systems:

� Proprietary or embedded

� Networking:� Low-end: no standard networking, proprietary control system

perhaps based on RS-232 or USB

� High-end: Stand-alone TCP/IP node, might user Power over Ethernet (PoE), DHCP, proprietary control protocol


Handheld Readers

� Handheld systems with integrated RFID reader and antenna� Sometimes integrated into

an existing barcodescanner product

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RFID-Basics-13


Handheld Reader Systems

� Handheld RFID scanner built into a handheld PC� Processors:

� Low-end to mid-range 32-bit processor plus DSP or FPGA for signal processing


� Typically WinCE

� Networking:

� Wireless TCP/IP network nodes that use DHCP and connect to servers (perhaps intermittently) using proprietary data transfer applications


Embedded Readers

� “Credit Card-sized” module, used to add RFID to a special-purpose device

� Examples: RFID printer/encoders, packagesorters and POS terminals(AKA cash registers)


Embedded Reader Systems

� Embedded reader is hosted in a special-purpose device� Processors:

� No general purpose CPU -- DSP or FPGA for signal processing

� Host system provides general purpose CPU


� None.

� Networking:� None. Accessed via USB, Serial interface or PCMCIA

� Host processor may have networking capability


Configuration Requirements

� Networking configuration similar to any end-node infrastructure device

� DHCP, configuration and firmware downloads

� Small amount of persistent RFID-specific and device-specific configuration� Power level, active antennas, possibly some protocol and search

settings

� Set/get administrative status

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RFID-Basics-14


RFID Configuration Challenges

� Minimal system requirements� Lower-end “smart antennas” may not have much processor or

memory available

� Needs to be configurable as a stand-alone device or as an entity within another device� Printer, cash register, handheld PC, etc.

� Good fit for an SNMP MIB?

� Minimal agent system requirements

� Subagent and Entity MIB allow configuration of an RFID “device within a device”


Monitoring Requirements

� Monitoring of network connectivity similar to any other infrastructure device

� Monitoring of RFID-specific parameters� Operational status

� Antenna connection faults

� RF problems/interference

� Perhaps some thresholding on read counts or other parameters?


Monitoring Challenges

� RFID market is in early stages, so there hasn’t been much time for de facto standardization

� Readers (even within a single category) have significantly different hardware/software capabilities


Control Requirements

� Most readers do not change roles regularly� Examples of reader roles:

� A reader continuously reads a fixed set of protocols

� A reader is set to read a fixed set of protocols, in a fixed cycle whenever the dock door is open (detected via GPIO)

� A reader reads a fixed set of protocols for a defined time period whenever an electric eye is triggered

� Challenge is not in controlling reader search parameters, it is in collecting, parsing and collating RFID data from multiple read points� A standard way to collect RFID “reads” from multiple readers

would be useful

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RFID-Basics-15


Control Requirement Questions

� Applications are needed to control the RFID reader, but at what level of abstraction?

� Individual read cycle vs. set and forget?

� Where are the applications hosted?

� May be hosted on workstation (reached over network), on a fixed reader, on a handheld PC or on the host processor for an embedded reader

� Are there any “real-time” requirements?

� Regulatory requirements demand real-time (sub-millisecond) control over RF functions

� Control at a higher levels may not be real-time at all


Ongoing Related Efforts

� Reader Configuration� De facto standard set of DHCP options with bootfile and

configuration file download mechanisms emerging due to network vendor/system integrator efforts

� Reader Monitoring� EPC Global Reader Management Group

� Defining MIBs for reader monitoring and RFID-specific configuration

� Reader Control

� EPC Global Reader Protocol Group� Defining an XML/Web Services interface for reader control

� See: http://www.epcglobalinc.com


Limitations of Tag and Reader Communications

� Because RF is analog, not digital, it is susceptible to degradation caused by interference from� Spurious RF noise sources� Environmental conditions

� Liquid such as water� Metal, foil or other metallic objects� High humidity� Extreme temperatures – very hot or very cold� Motors or engines� Wireless devices such as cell phones and PDAs� Wireless computers or communication networks� Cordless phones

� Degree of interference is also affected by operating frequencies.


How to Overcome Limitations?

� Choose a suitable operating frequency � Select appropriate tags and readers

� Properly install and deploy antennas

� Extensive trials and pilots� RF physics

� Sophisticated software solutions that implement

� Error correction

� Fault tolerance

� Redundancy

EPC Network - Industrial Applications of RFID...

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