an overview of the iso rfid data protocol & library applications paul chartier project editor...
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An Overview of the ISO RFID Data Protocol & Library Applications
Paul Chartier
Project Editor ISO/IEC 15961 & 15962
June 2006
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
A Basic Question: “Why Standards?”
BSI defines standardisation as the process of “establishing and applying an agreed set of solutions intended for repeated application, directed at benefits for stakeholders and balancing their diverse interests.”
The library community has developed and adopted a broad variety of standards
- but not yet for RFID
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
Some Benefits of RFID Standards
Specifies the rules for components to be fit for purpose Establishes interoperability of RFID devices Establishes compatibility between library systems but
still supports flexible applications Avoids systems clash with other applications - given
that RFID tags on library items move around the community
Stakes a claim for library systems so that other RFID systems do not corrupt library applications
Provides a better chance of migration as technology improvements are made
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
RFID SystemThe Generic Model
RFIDTagAir interfaceApplication protocolData
content
APPLICATION
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
RFID Standards Types of Standard
Technology - air interfacedefines what it does
Conformance & Performancecompares actual devices with standards
“Middleware” protocolshow data and instructions are processed
Data contenthow business data is supported
Applicationsmaking it work for a specific sector
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
ISO RFID StandardsAir Interface Standards
Various aspects can be covered, but key are: The air interface: frequency, modulation, bit encoding Anticollision
– the ability to almost simultaneously address a number of tags unambiguously
– not always a requirement Commands and responses that address memory in
terms of blocks (or words, or pages)
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
Tag ArchitectureISO/IEC 18000-3 Mode 1
Single memory Can emulate a UII by
placing this first Separate TID and
System Info (inc AFI) Block size & number
of blocks can vary
SYST EM INFO
UNIQUE T AG ID
includes Application Fam ily Id Data Form at
optional
NUM BER OF BLOCKS
BLOCK SIZE
Each block can beaddressed individuallyand blocks can belocked selectively
T his area containsall the application dataconcatenated inone sequence
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
An RFID Implementation Based Only on the Air interface
Interrogator(Reader /Encoder)
An
ten
na
RF T ag
Air InterfaceCom m ands
AirInterfaceResponses
ApplicationSoftware
ISO/IEC 18000
AIR INT ERFACERESPONSES
AIR INT ERFACECOMMANDS
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
Implications of the Application Working at the Air interface Level
Memory map has to be pre-defined for encoding New data requires a new “message” or memory map
rule Need to understand the memory map to read data Need to use RFID air interface commands Data might not be encoded most efficiently Data might not be encoded most efficiently, especially
variable length and optional data
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
APPLICATION PROTOCOL STANDARDS
Data Protocol
The Data Protocol addresses data handling between the application and the RF tag
ISO/IEC 15961 Data protocol - application interface:– defines the application commands and responses– uses object identifiers to define all data types
ISO/IEC 15962 Data protocol - data encoding rules– efficient encoding of object identifiers– common data compaction
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
RFID Data ProtocolPositioning ISO/IEC 15961 & 15962
Interrogator(Reader /Encoder)
An
ten
na
RF T ag
Air InterfaceCom m ands
AirInterfaceResponses
ApplicationSoftware
ISO/IEC 18000
APPLICAT IONCOM M ANDS
APPLICAT IONRESPONSES
ISO/IEC15961
Data ProtocolProcessor
Encoder
Decoder
Command /Response
UnitLogicalM emory
TagDriver(s)
ISO/IEC15962
ISO/IEC 15962
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
RFID Data ProtocolOverview
In terrogatorReader / Encoder
Antenna
Air InterfaceCom m ands Air Interface
Responses
Application Software
• The Data Protocol fills a gap in communications
In terrogatorReader / Encoder
Antenna
Air InterfaceCom m ands Air Interface
Responses
Application Software
Data ProtocolApplication Interface
ISO/IEC 15961
• Business issues are addressed by the Application Interface
• This generates commands and processes responses Interrogator
Reader / Encoder
Antenna
Air InterfaceCom m ands Air Interface
Responses
Application Software
ApplicationCom m ands
Data ProtocolApplication Interface
ISO/IEC 15961
In terrogatorReader / Encoder
Antenna
Air InterfaceCom m ands Air Interface
Responses
Application Software
ApplicationCom m ands Application
Responses
Data ProtocolApplication Interface
ISO/IEC 15961
• The encoding rules convert the data in the commands into efficient encoding on the RF tag
In terrogatorReader / Encoder
Antenna
Air InterfaceCom m ands Air Interface
Responses
Application Software
ApplicationCom m ands Application
Responses
Data ProtocolApplication Interface
ISO/IEC 15961
Data ProtocolEncoding RulesISO/IEC 15962
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
RFID Data ProtocolISO/IEC 15961 Application Interface
In terrogatorReader / Encoder
Antenna
Air InterfaceCom m ands Air Interface
Responses
Application Software
ApplicationCom m ands Application
Responses
Data ProtocolApplication Interface
ISO/IEC 15961
Data ProtocolEncoding RulesISO/IEC 15962
Application Interface
Format O bject Identifier
System Information
C ommand & R esponseApplication Family Data Format Access Method
Generated based on ASN.1• Abstract syntax• Transfer encoding
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
RFID Data Protocol ISO/IEC 15961 Object Identifiers
Object identifiers used for selective read / write Based on ISO/IEC 9834-1 established rules and structures ISO/IEC 9834-1 allows systems to define objects to any
level of granularity - just need an object ID A typical object identifier: 1 0 15961 127 13 The Hierarchical structure ensures uniqueness of objects Therefore, possible to encode different data, including
closed system objects with no risk of corruption Extension techniques make the system totally expandable
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
ISO/IEC JTC1/SC31 Logical Tag Structure
SYST EM INFO
UNIQUE T AG ID
includes Application Fam ily Id Data Form at
optional
NUM BER OF BLOCKS
BLOCK SIZE
Each block can beaddressed individuallyand blocks can belocked selectively
T his area containsall the application dataconcatenated inone sequence
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
ISO/IEC Air Interface & Data ProtocolSystem Information
This provides a protocol level - not data - method for managing the interface between application and RF tag, and includes:
Application Family: to enable a subset of RF tags to be in the communication channel
Data Format: to specify the interpretative nature of the encoded bytes on the RF tag
Access Method: to create a logical structure of the bytes encoded on the RF tag
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
ISO/IEC Air Interface & Data ProtocolSystem Information: Application Family
There is a real need to manage the transactions across the air interface– with large population of tags– where there is a risk of different types of tag being
present To be compatible with smart card rules (SC17), RFID
for Item Management has to co-manage some codes Application Family codes are allocated to focus on a
meaningful subset within the system, thus excluding RF tags from other systems
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
The AFIA Tool for Efficient Communications
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
The AFI: A Powerful Tool to Select Only Relevant Tags
Reader
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
RFID Data ProtocolISO/IEC 15962 Data Encoding Rules
InterrogatorReader / Encoder
Antenna
Air InterfaceCommands Air Interface
Responses
Application Software
ApplicationCommands Application
Responses
Data ProtocolApplication Interface
ISO/IEC 15961
Data ProtocolEncoding RulesISO/IEC 15962
InterrogatorReader / Encoder
Data Protocol Processor
D ata C om pac to r
D ata F o rm atte r
Log ical Mem ory
T ag Driver
Consider this like a bar code encoder, but common to many RF tags
Each different air interface has its own Tag Driver, determining precise mapping rules
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
ISO/IEC 15962Data Compaction Schemes The ISO/IEC 15962 process looks, on a case by case basis of
each data object, at the byte encoding on the RF tag It selects the most efficient encoding scheme from the alternatives
(the most efficient scheme is at the top of this list) – Integer: encodes number as binary– Numeric: 4 bits per digit– 5-bit: uppercase alphabetic– 6-bit: uppercase alphabetic, numeric, etc– 7-bit: all ISO 646 (US ASCII)– Octet: unaltered 8-bit
It also preserves user-defined data and supports UTF-8 for international character sets
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
ISO/IEC 15962Logical Memory
A software representation of the RF tag memory
Structured by extracting the system information from the RF tag
Structure– width = block (or codeword) size– length = number of blocks (or codewords)
LogicalM emory
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
RFID Data ProtocolRevisions to ISO/IEC 15961 & 15962
15961-1: 15961 (pub October 2004) needs to be simplified with respect to the data constructs topics
New application commands for 18000-6C and sensors
15961-2: Rules for new Registration Authority for AFIs and other data constructs
15961-3: Specification of data constructs 15962: New encoding and data mapping
processes for 18000-6C and sensors
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
ISO/IEC 15961Data Constructs
Application Family Identifier (AFI): Used to manage selection across air interface
Data Format: A “shorthand” code to truncate the encoding of long Object Identifiers
Object Identifier for UII - Register of key traceability codes
Object Identifier for other item-attendant data - Register of OID structure for other data
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
Library CommunityData Constructs Process - with SC31
EDItEUR has made initial request for registration, with the understanding that the application was incomplete
The assignment of data constructs for libraries is accepted Additional information required for:
– Object Identifier for primary code– Object Identifier structure for additional data objects
JTC1/SC31 WG4 has a procedure that can approve the registration and assign the AFI and Data Format
The data constructs will be published and maintained on the web
Libraries & ISO RFID Standards June 2006Copyright praxis consultants,2006
Library CommunityData Constructs - within the Sector
Define data objects (e.g. ISIL, ISBN) Specify data objects
– format (e.g. alphanumeric, numeric, UTF-8)– fixed or variable length– fixed or maximum length
Specify relative-OID value Extend and revise with no constraints from SC31/WG4
Thank you for your attention