WO2007065747A1

WO2007065747A1 - Rfid tag-based file system and associated access methods

Info

Publication number: WO2007065747A1
Application number: PCT/EP2006/067197
Authority: WO
Inventors: Marcos Dos Santos Rocha; Alois Ferscha; Marquart Franz; Manfred Hechinger; Rene Mayrhofer; Andreas Zeidler
Original assignee: Siemens Aktiengesellschaft
Priority date: 2005-12-09
Filing date: 2006-10-09
Publication date: 2007-06-14
Also published as: DE102005058967A1

Abstract

The invention essentially relates to a distributed RFID file system as well as methods for transparently accessing data that is distributed to one or several transponders which can be combined to a cluster having a correspondingly larger storage capacity. A cluster is provided with two types of RFID tags, i.e. cluster management transponders for organizing and cluster data transponders for storing the actual data sets, resulting in fast transparent access to data, fast and inexpensive adjustment of the transponder storage capacity by adding or removing writable RFID tags, and increased data robustness by means of the distributed storage.

Description

File system based on RFID tags and associated

Access method

The invention relates to a file system based on RFID tags and associated access methods, in which data is distributed on one or more transponders. Delivery-relevant data in the logistics industry have so far not been available either on optically readable

writable 2D bar codes with only very small

Storage capacity or stored on individual so-called RFID tags with a relatively limited capacity. Location-based information is currently mostly stored centrally on one or more computers, e.g. in the

Internet / intranet. Personal portable data storage, such as USB stick, compact flash card, portable hard disk and. s. w., are relatively expensive and can only be obtained via connectors

communicate - spontaneous, transparent communication is not possible with this. Furthermore, in this

Data is also stored on more expensive devices that are connected via a more complex radio interface, e.g. Bluetooth or WLAN. These more complex radio technologies

however require an external energy source, e.g. a battery or a power connector.

RFID (radio frequency identification) is a technology that enables data on so-called RFID transponders to be read and closed contactlessly and without visual contact

to save. An RFID transceiver reads or writes the information using radio waves

performed. At low frequencies this is done inductively via a near field, at higher frequencies via an electromagnetic far field. The distance over which an RFID transponder can be read currently ranges from a few millimeters to several meters, depending on the version. RFID tags can based on either active or passive transponders. Active transponders have an external energy source, e.g. a battery, which enables them to send data at any time. Passive transponders, on the other hand, get the energy they need from the radio waves of the reader. That is why they can only send if they are addressed by a reader, but are much cheaper and easier to maintain than active RFID tags. Implement modern RFID tags

deterministic or probabilistic time-division multiplexing for anti-collision to enable the parallel reading of several RFID tags. Leading RFID systems currently allow quasi-parallel reading of 200 RFID tags. In addition, more complex RFID tags are also able to hold data

encrypted to transmit. The storage capacity of common passive RFID tags is currently in the range of one bit to about 72 KB. With regard to multimedia data and

encrypted / signed documents, the storage capacity of individual tags is quickly used up. From the international patent application WO99 / 49335, for example, a communication method between a large number of such units and a control unit is known.

From the publication "The RFID Filesystem Whitepaper", Athens University of Economics and Business, Achilleas

Anagnostopoulos, 2005, also discloses a file system for a single RFID tag.

Finally, from the publication "Cascading RFID Tags", Jeffrey D. Lindsay and Walter Reade, Nov 2003,

Describes a nested or hierarchical system of RFID tags according to packaging levels of products.

Nested RFID transponders are used for this purpose. Redundant information is distributed over several RFID To save transponders, what the robustness and the

Accessibility of the stored data increased.

With the first version of QDOS published in 1980, the FAT (file allocation table) was introduced as a file system.

Initially, no subdirectories were administered. This changed with MS-DOS ® version 2.0. The FAT is a linked list in a storage area of a partition, in which information about each cluster, i.e. everyone

Allocation unit, a partition stand. This information can mean, for example, that the cluster is free, that the

Medium at the location of this cluster is damaged, that the cluster is occupied by a file and that the next cluster of the file is the cluster with the number X or that this is the last cluster of the file.

The object on which the invention is based is now to specify a file system based on RFID tags and associated access methods in which the disadvantages mentioned above are avoided.

This object is achieved by the features of claim 1. The further claims relate to preferred configurations of the file system according to the invention and corresponding access methods.

The invention essentially consists of a distributed RFID file system and of methods for transparent access to data which are distributed on one or more transponders, wherein several RFID transponders can be combined to form a cluster with a correspondingly larger storage capacity and a cluster of two types of RFID tags, namely cluster management transponders for organization and cluster data transponders for storing the actual data records. This will make one faster

transparent access to data, fast and

Cost-effective adaptation of the transponder memory capacity by adding or removing writable RFID tags and an increased data robustness among other things due to the distributed

Storage reached.

The invention is explained below with the aid of the drawing using preferred exemplary embodiments.

Because passive RFID tags are much cheaper and easier to maintain than active RFID tags, they concentrate

Application examples on passive RFID tags, although the

Invention also based on active RFID tags in

correspondingly is not difficult to implement.

In the file system according to the invention based on RFID tags, clusters of RFID tags are formed, preferably by gluing, of several RFID tags, the RFID tags

are at least so close to one another that they can still be detected together by an RFID reader / writer, and these clusters have two types of RFID tags or transponders, namely cluster management transponders and

Cluster data transponder.

Cluster management transponder

Such a management transponder 2 stores the file directory including a reference to the physical location where the data is actually stored.

Depending on the cluster size, the file directory and the FAT can be stored on one or more management transponders 2, 2 '.

The first bytes of a management transponder formatted for the file system according to the invention contain information 21 on the file system ID and version, information 22 on the transponder memory, such as, for. B. number of blocks and bytes per block, a unique transponder identifier 23, one

Cluster tag IDs list 24 with the IDs of the transponders belonging to the cluster and a FAT (file allocation table) or File allocation table 25. The FAT contains an entry for each file with the following content: file name, file size and a reference to the beginning of a linked list of transponder blocks, the FAT containing an entry for each data block on the RFID transponder cluster , whereby if the FAT is stored on several transponders, the IDs of the following management transponder

are stored and the rest of the writable part of the transponder memory by the so-called

Data blocks are occupied, which contain the actual file contents.

Cluster data transponder

Such a data transponder 1 represents the storage location of the actual data records.

The first bytes for the data transponder formatted for the file system according to the invention contain information 11 on the file system ID and on the version, information 12 on the

Transponder memory, such as the number of blocks and the number of bytes per block, a unique

Transponder identifier 13, optionally followed by an identifier 14 of the responsible management transponder. This

The identifier 14 is therefore optional since a data transponder is also an inexpensive, pure read-only memory (ROM), e.g. B. for origin data, can be that contains no dynamic data and fixed during the manufacturing process

is described. In this case, this data field remains free and the data transponder can only be addressed by its reference from the management transponder. The rest of the writable part of the transponder memory is occupied by data blocks 15, which are the actual ones

File contents included. Concepts, e.g. RAID5, to increase robustness,

Metadata in particular can be taken from the area of redundant data storage and also optionally in Find application in the file system of the invention. In the ideal case, the data of the FAT are distributed in such a way that they can be completely reconstructed, even if certain transponders or data blocks are illegible.

The management tags ensure that complete

Records are read. All transponders and data blocks on which a certain file is saved are saved in the management tags.

If the transponder is also optional

Support cryptographic process, which only allows tags to be written by authenticated systems, the data held on the management tags can be used to manipulate data records, e.g. by removing or exchanging a tag. This can be interesting if the documentation is complete

legal or economic reasons. Here is e.g. the use in the field of dangerous goods should also be mentioned.

The management and data transponders are used at

Established such a cluster. This process is called cluster initialization and requires that

Use of an RFID read / write device.

If transponders are added to or removed from a cluster afterwards, the FAT must be set to the

affected management transponders are updated.

The corresponding access methods are explained below using a simple exemplary embodiment with a cluster management transponder and two cluster data transponders: Cluster initialization

The management and data transponders are combined in a logical cluster. During production, the tags are provided with a file system ID, information about the

Transponder memory and a unique transponder

Provide identifier. The RFID reader / writer scans the surroundings and finds the transponders 1, 2 and 2 'available there. The user uses the transponder identifiers to select the transponders that are combined into a cluster - alternatively, all the transponders found in the area are automatically combined into a cluster when the user initiates the initialization. The RFID read / write device bears the identifier of the selected one

Management transponders in the management tag ID field 14 of the data transponders. The RFID read / write device enters the list of identifiers of the data transponders in cluster tag ID list 24 of the management transponder 2. The FAT 25 of the management transponder is initialized empty. Add RFID data transponders to a cluster

The RFID reader / writer scans the environment and finds the management and data transponders 1, 2 available there. The cluster tag ID lists 24 on the management transponders are read out. The data transponders found in the area and not in any management transponder

can be added to the existing clusters. Based on the cluster identifier and the list of available data transponders, the user selects which transponders are added to which cluster - alternatively, all "free" data transponders are automatically added to the existing cluster. The RFID reader / writer carries this Enter the identifier of the selected management transponder in the management tag ID field 14 of the data transponder 1. The RFID reader / writer carries the list of identifiers of the data transponders in the cluster tag ID list 24 of the management -Transponders 2 a. Removing RFID data transponders from a cluster The RFID reader / writer scans the environment and finds a management transponder 2 a cluster of the

file system according to the invention. The cluster tag ID list 24 of the management transponder and the FAT of the file system according to the invention are read out. The identifiers of the unused data transponders are determined and displayed by the RFID reader / writer. From this list, the user selects the data transponders that should be removed.

Read data

The RFID reader / writer scans the surroundings and finds a management transponder 2 or cluster of the

file system according to the invention. The cluster FAT, i.e. the management transponder, is read out. The software management module recognizes a file for which it is

interested, e.g. File Karte.jpg, and causes it to be read out. The RFID read / write device reads the transponder data blocks that are referenced in the FAT, summarizes them and passes them on to the software management module. Checksums are calculated by the software management module and the integrity of the data is thus checked. Optionally, the redundancy added by the software management module is used to recover lost data

reconstruct. The file is available for processing by the software management module.

Writing data

file system according to the invention.

The cluster FAT 25, i.e. the management transponder, is read out. The size of the available memory in the cluster is checked by the software management module. The software management module causes a file to be saved on the cluster. Data redundancy is optional added to increase data robustness, e.g.

Checksum or parity etc. The RFID reader / writer enters in the FAT the list of data blocks on which the file will be saved. The RFID read / write device writes the name of the file into the FAT of the management

Transponder and references the data blocks where the file was saved. The RFID read / write device writes the individual data blocks to the data transponder. advantages

The method described here enables transparent reading and writing of data records of "any" size on RFID transponders. The required storage capacity of an RFID transponder cluster can be adapted ad-hoc by adding / removing transponders.

In contrast to known “nested RFIDs” mentioned at the outset, the invention enables transparent writing and reading of larger data records on distributed RFID transponders, since the RFID transponders in the invention are combined to form a logical data memory.

Passive RFID tags in particular are cheap because they do not require a battery. RFID tags also do not require

Contact-based connection to a read / write device and are therefore potentially suitable for an infinite number of read processes since there is no wear on the contacts.

RFID tags are very robust, they can be difficult

Endure environmental conditions. Contactless reading and

Writing RFID transponders enables additional ones

Security for the data through physical protection of RFID transponders, e.g. by enclosing RFID transponders in a safety box. The data robustness can be increased by storing redundant data on distributed RFID tags. This can be done completely transparently for the user. An overview of the IDs from local

Available RFID transponders can be read by few cluster management RFID transponders can be implemented, which can greatly reduce the scan time. An overview of the data on several RFID tags can be quickly created by reading out cluster management RFID transponders. Mutual

Overwrite important data within one

Transponder clusters become central through the cluster

managed FAT prevented. Due to the controlled range of the reading terminal, transponder clusters are particularly suitable for storing complex, location-relevant information. It is possible to integrate inexpensive read-only tags in the file system according to the invention.

Claims

1. File system based on RFID tags,

where several RFID tags form a cluster,

in which at least one cluster management transponder for organization and at least one cluster data transponder for storing the data records of the cluster

File system. 2. File system according to claim 1,

in the cluster of RFID tags are formed in that several RFID tags are glued at least so close to one another on a common base that they can still be detected together by an RFID reader / writer.

3. File system according to claim 1 or 2,

where the cluster management transponders contain at least the following:

1. Information (21) on the file system ID and version;

2. Information (22) about the transponder memory itself;

3. a unique transponder identifier (23);

4. a cluster tag ID list (24) with the IDs of the transponders belonging to the respective cluster and

5. a file allocation table (25)

4. File system according to claim 3,

in which a file directory and the file allocation table are stored on several management transponders (2, 2 '), only the first cluster management transponder (2) having a cluster tag ID list (24).

5. File system according to one of claims 1 to 4,

where the cluster data transponders contain at least the following:

1. Information (11) on the file system ID and

Version;

2. Information (12) on the transponder memory;

3. a unique transponder identifier (13) and

4. Data blocks (15) which contain the actual file contents.

6. File system according to claim 5,

in which a respective cluster data transponder also has an identifier (14) of the person responsible for it

Has management transponders.

7. Access method for a file system according to claim 1, in which for cluster initialization

a. during manufacture, the RFID tags are provided with at least a file system ID, information about the transponder memory and a unique transponder identifier,

b. from an RFID read / write device in one

certain range of available transponders (1,2) are recorded,

c. Transponders are combined into a cluster, d. from the RFID reader / writer the identifier of the

selected management transponder is entered in a management tag ID field (14) of the relevant data transponder,

e. the list of identifiers of the data transponders is entered into the cluster tag ID list (24) of the management transponder by the RFID reader / writer and f. the file allocation table (25) of the management transponder is initialized empty.

8. A file system access method according to claim 1, wherein to add data transponders to one

Cluster

a. from an RFID read / write device in one

certain range of available transponders (1, 2) are recorded,

b. Cluster tag ID lists (24) are read out on the management transponders (2), the data Transponders that were found in the area and are not entered in any management transponder can be added to the existing clusters,

c. addable data transponders are added to the existing cluster,

d. from the RFID reader / writer the identifier of the

selected management transponder is entered in the management tag ID field of the added data transponder and

e. the list of identifiers of the data transponders is entered into a cluster tag ID list (24) of the management transponder by the RFID reader / writer.

9. Access method for a file system according to claim 1, in which to remove data transponders from one

Cluster

a. from an RFID read / write device in one

certain range of available transponders (1,2) are recorded,

b. a cluster tag ID list (24) of the management transponder and the file allocation table (25) of the file system are read out and

c. identifiers of the unused data transponders are determined by the RFID reader / writer and displayed for selection for removal.

10. A file system access method according to claim 1, wherein for reading data

a. from an RFID read / write device in one

certain range of available transponders (1,2) are recorded,

b. a file allocation table (25) of the management transponder is read out and

c. a file or a certain file type is recognized and read by a software management module,

- that of the RFID read-write device

Transponder blocks of data are read in the file allocation table are referenced, and these are summarized and passed on to the software management module, and

- That the software management module calculates checksums and thus the integrity of the

Data is checked.

11. Access method for a file system according to claim 1, in which for writing data

a. from an RFID read / write device in one

certain range of available transponders (1,2) are recorded,

b. a file allocation table (25) of the management

Transponder is read out,

c. the size of a software management module

available memory in the cluster is checked, d. is caused by a software management module that at least the data of a file to be saved are stored on the cluster,

e. from the RFID reader / writer to the

Data assignment table the list of data blocks on which the file will be stored is entered,

f. the name of the file is written by the RFID reader / writer into the file assignment table of the management transponder and the data blocks are referenced there, where the file was stored, and

G. the individual from the RFID reader / writer

Data blocks are written on the data transponder.