Anti-collision coupling for contactless cards
Contactless cards and a corresponding anti-collision coupling method are provided, where the method includes requesting that the cards transmit their unique identifiers that each include a fixed number of bytes, receiving the unique identifiers simultaneously as byte-wise positive pulses, counting the received positive pulses, and determining that more than one card responded if the number of received positive pulses exceeds the fixed number of bytes; and where the contactless cards each include a unique identifier having a number of bytes, a receiver for receiving an anti-collision command indicative of a desired identifier byte, a comparator in signal communication with the receiver for comparing the desired identifier byte with a corresponding byte of the unique identifier, and a transmitter responsive to the comparator for transmitting the unique identifier as byte-wise positive pulses if the desired identifier byte matches the corresponding byte of the unique identifier.
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The present disclosure relates to contactless interface devices, and more particularly relates to anti-collision coupling for contactless interface devices. An anti-collision coupling for contactless interface devices is provided.
Contactless integrated circuit (IC) cards and radio frequency (RF) identification (RFID) cards are types of contactless interface devices known as contactless cards. In such contactless cards, an interface coupling or information exchange may be accomplished when the contactless cards come within range of a contactless card reader.
If more than one contactless card approaches a reader at the same time, there may be confusion in the reader because of multiple concurrent signals from each card. To alleviate such confusion, an anti-collision interface coupling method is used to identify the cards that approach the reader.
The anti-collision coupling methods for contactless cards are typically divided into close coupling methods and remote coupling methods, according to the desired approach distance between a card and a reader. In addition, the remote coupling methods are typically divided into proximity, vicinity and RF methods.
An example of a close coupling method (CICC) is set forth in the ISO 10536 standard, as known in the art. Examples of proximity coupling methods (PICC) are set forth in the ISO/IEC 14443 standard, as also known in the art. An example of a vicinity coupling method (VICC) is set forth in the ISO/IEC 15693 standard, as further known in the art.
The PICC methods defined in the ISO/IEC 14443 standard include a type A coupling method and a type B coupling method. For the type A method, the anti-collision method of the contactless cards that satisfy the ISO 14443 type A standard make use of a Unique Identification (UID), which each card has separately. When the contactless cards approach an effective region of the reader, the contactless cards each generate a signal to indicate their presence, the reader requests a card to transfer its UID, the card transfers the UID to the reader by unit, and the reader identifies the card by comparing the UID separately. The ISO 14443-A standard uses a UID method and a bit collision method, where the card is required to respond within a precise response time. Unfortunately, it takes the card a long time to respond because of the bit unit identification required within each card.
For the type B method, the anti-collision method of the contactless cards that satisfy the ISO 14443 type B standard makes use of an optional value called a Pseudo Unique Proximity card Identifier (PUPI), which each card generates separately. When the contactless cards approach an effective region of the reader, the reader requests the cards to generate a random value having a set scope, the cards each generate PUPI values different from each other, and the reader selects a card by calling one of the received PUPI values. In the ISO 14443-B standard, the card must generate a random value within a fixed range and the reader must generate slots. Unfortunately, this process takes a long time because of the card operation required within each card.
For the vicinity method, the anti-collision method of the contactless cards that satisfy the ISO 15693 standard makes use of a Unique Identification (UID), which each card has separately. When the contactless cards approach an effective region of the reader, the reader generates a slot having sixteen values whenever an EOF occurs. The reader requests a card to transfer a UID and recognizes the card by noting that the card responds to a slot that has the same value as its UID. The ISO 15693 standard uses a UID method, where the reader must make 16 slots. The card responds to the corresponding slot when the UID is in accord with the slot. The card compares its UID with the slots 0 to 16, and counts the slot whenever the EOF occurs. Unfortunately, this process takes a long time because of the card operation required within each card. Thus, conventional methods for anti-collision coupling suffer from the disadvantage that a complex arithmetic operation is required within each card. The above and other drawbacks and disadvantages of the prior art are addressed by an anti-collision coupling for contactless cards in accordance with exemplary embodiments of the present disclosure.
SUMMARY OF THE INVENTIONContactless cards and a corresponding anti-collision coupling method are provided. An exemplary embodiment anti-collision coupling method includes requesting that contactless cards transmit their unique identifiers that each include a fixed number of bytes, receiving the unique identifiers simultaneously as byte-wise positive pulses, counting the received positive pulses, and determining that more than one card responded if the number of received positive pulses exceeds the fixed number of bytes.
Exemplary embodiment contactless cards include a unique identifier having a number of bytes, a receiver for receiving an anti-collision command indicative of a desired identifier byte, a comparator in signal communication with the receiver for comparing the desired identifier byte with a corresponding byte of the unique identifier, and a transmitter responsive to the comparator for transmitting the unique identifier as byte-wise positive pulses if the desired identifier byte matches the corresponding byte of the unique identifier.
These and other features of the present disclosure will become apparent from the following description of exemplary embodiments, which is to be read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGSThe present disclosure presents an anti-collision coupling for contactless cards in accordance with the following exemplary figures, in which:
The present disclosure relates to contactless integrated circuit (IC) cards and radio frequency (RF) interface devices (RFID), and more particularly relates to anti-collision methods for interfacing such cards and devices. An exemplary method is used to identify a number of contactless IC or RFID cards associated with a reader by using a unique identification (UID) of each of the cards when a plural number of cards approach the reader. The method identifies each card to prevent collisions between the cards without requiring complex arithmetic operations by the cards. As shown in
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As shown in
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Thus, each card that receives the call command transfers its UID to the reader as positive pulses. The UID 610 of Card 1 includes a first UID byte value of 150, a second UID byte value of 180 and a third UID byte value of 180. The UID 620 of Card 2 includes a first UID byte value of 100, a second UID byte value of 80 and a third UID byte value of 80. The UID 630 of Card 3 includes a first UID byte value of 150, a second UID byte value of 120 and a third UID byte value of 120. The composite UID signal 640 at the reader includes first UID byte values of 100 and 150, second UID byte values of 80, 120 and 180, and third UID byte values of 80, 120 and 180.
As shown in
If the decision block S640 determines that more than one card responds to the reader, control is passed to a function block S660, at which the reader selects a second UID byte from among the second UID bytes received in the composite UID and calls the corresponding card. That block passes control to a decision block S670, which determines if more than one card still responds to the reader. If only one card responds to the reader, the block S670 passes control to another decision block S680, which determines if the reader has called all of the second UID bytes received in the composite UID signal. If the reader has not yet called all of the second UID bytes, control is passed back to the function block S660. If, on the other hand, the reader has already called all of the second UID bytes, control is passed to the function block S700.
If the decision block S670 determines that more than one card still responds to the reader, control passes to a function block S690. At the function block S690, which represents a recursive loop duplicating steps S630 through S650 or S660 through S680 for up to an nth UID byte (e.g., n=3,4,5 . . . ), the reader selects an nth UID byte from among the nth UID bytes received in the composite UID signal and calls the corresponding card. The function block S690 passes control to the function block S700.
Turning now to
The signal 900 further includes a start and an end using a Start of Frame (SOF) and an End of Frame (EOF), respectively. The reader 510 transfers the SOF and the UID call command and the SOF when the contactless cards 520, 530 and/or 540 approach the reader.
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It is to be understood that the teachings of the present disclosure may be implemented in various forms of hardware, software, firmware, special purpose processors, or combinations thereof. Most preferably, the teachings of the present disclosure are implemented as a combination of hardware and software. Moreover, the software is preferably implemented as an application program tangibly embodied on a program storage unit. The application program may be uploaded to, and executed by, a machine comprising any suitable architecture. Preferably, the machine is implemented on a computer platform having hardware such as one or more central processing units (“CPU”), a random access memory (“RAM”), and input/output (“I/O”) interfaces. The computer platform may also include an operating system and microinstruction code. The various processes and functions described herein may be either part of the microinstruction code or part of the application program, or any combination thereof, which may be executed by a CPU. In addition, various other peripheral units may be connected to the computer platform such as an additional data storage unit and a printing unit.
It is to be further understood that, because some of the constituent system components and methods depicted in the accompanying drawings are preferably implemented in software, the actual connections between the system components or the process function blocks may differ depending upon the manner in which the present disclosure is programmed. Given the teachings herein, one of ordinary skill in the pertinent art will be able to contemplate these and similar implementations or configurations of the present disclosure.
Although illustrative embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope or spirit of the present invention. All such changes and modifications are intended to be included within the scope of the present invention as set forth in the appended claims.
Claims
1. A method of detecting at least one contactless device that has a unique identification code (UID), the method comprising:
- requesting transfer of a UID;
- receiving at least one positive pulse indicative of a UID; and
- detecting whether more than one UID was transferred if the number of positive pulses received exceeds the number expected for one UID.
2. A method as defined in claim 1 wherein the UID comprises at least one byte, each byte being received in the shape of a positive pulse.
3. A method as defined in claim 1 wherein one UID was transferred, the method further comprising activating the device corresponding to the transferred UID.
4. A method as defined in claim 2 wherein more than one UID was detected, the method further comprising:
- selecting a first UID byte from the received UID bytes;
- requesting transfer of a UID having the selected first UID byte;
- receiving at least one positive pulse indicative of a UID; and
- detecting whether more than one UID having the selected first UID byte was transferred if the number of positive pulses received exceeds the number expected for one UID.
5. A method as defined in claim 4 wherein one UID having the selected first UID byte was transferred, the method further comprising activating the card corresponding to the transferred UID.
6. A method as defined in claim 4 wherein more than one UID having the selected first UID byte was detected, the method further comprising:
- selecting a second UID byte from the received UID bytes;
- requesting transfer of a UID having the selected first UID byte and the selected second UID byte;
- receiving at least one positive pulse indicative of a UID; and
- detecting whether more than one UID having the selected first UID byte and the selected second UID byte was transferred if the number of positive pulses received exceeds the number expected for one UID.
7. A method as defined in claim 6 wherein one UID having the selected first UID byte and the selected second UID byte was transferred, the method further comprising activating the card corresponding to the transferred UID.
8. A method as defined in claim 6 wherein more than one UID having the selected first UID byte and the selected second UID byte was detected, the method further comprising:
- selecting another UID byte from the received UID bytes;
- requesting transfer of a UID having the selected first UID byte and the selected second UID byte and the selected other UID byte;
- receiving at least one positive pulse indicative of a UID; and
- detecting whether more than one UID having the selected first UID byte and the selected second UID byte and the selected other UID byte was transferred if the number of positive pulses received exceeds the number expected for one UID.
9. A method as defined in claim 8 wherein one UID having the selected first UID byte and the selected second UID byte and the selected other UID byte was transferred, the method further comprising activating the card corresponding to the transferred UID.
10. A method of identifying a contactless device having a unique identification code (UID) to a reader, the method comprising:
- receiving a UID call command from a reader; and
- transferring at least one positive pulse indicative of the UID to the reader.
11. A method as defined in claim 10, further comprising:
- receiving an anti-collision command and at least one UID value from a reader; and
- if the at least one UID value from the reader matches a corresponding portion of the UID of the device, transferring at least one positive pulse indicative of the UID to the reader.
12. A reader for detecting at least one contactless device that has a unique identification code (UID), the reader comprising:
- a UID call commander for requesting transfer of a UID;
- a receiver in signal communication with the UID call commander for receiving at least one positive pulse indicative of a UID; and
- a detector in signal communication with the receiver for detecting whether more than one UID was transferred if the number of positive pulses received exceeds the number expected for one UID.
13. A reader as defined in claim 12 wherein the UID comprises at least one byte, the receiver disposed for receiving each byte in the shape of a positive pulse.
14. A reader as defined in claim 12, further comprising an activation unit in signal communication with the detector for activating a contactless device corresponding to a transferred UID.
15. A reader as defined in claim 13 disposed for detecting more than one UID, further comprising:
- a byte selector in signal communication with the detector for selecting a UID byte from the received UID bytes; and
- an anti-collision commander in signal communication with the byte selector for requesting transfer of a UID having the selected UID byte,
- wherein the receiver is disposed for receiving at least one positive pulse indicative of a UID responsive to the anti-collision commander and the detector is disposed for detecting whether more than one UID having the selected UID byte was transferred if the number of positive pulses received exceeds the number expected for one UID.
16. A contactless device comprising:
- a memory for storing a unique identification code (UID);
- a receiver in signal communication with the memory for receiving a command from a reader;
- a command interpreter in signal communication with the receiver for determining whether to transmit the UID; and
- a transmitter in signal communication with the memory for transmitting at least one positive pulse indicative of the UID to the reader.
17. A contactless device as defined in claim 16 wherein the command interpreter determines to transmit the UID if a UID call command is received, or if an anti-collision command and at least one UID value are received where the at least one UID value matches a corresponding portion of the UID of the contactless device.
18. A program storage device readable by a machine to execute program steps for detecting at least one contactless device that has a unique identification code (UID), the program steps comprising:
- requesting transfer of a UID;
- receiving at least one positive pulse indicative of a UID; and
- detecting whether more than one UID was transferred if the number of positive pulses received exceeds the number expected for one UID.
19. A program storage device as defined in claim 18 wherein the UID comprises at least one byte, each byte being received in the shape of a positive pulse, and more than one UID was detected, the program steps further comprising:
- selecting a UID byte from the received UID bytes;
- requesting transfer of a UID having the selected UID byte;
- receiving at least one positive pulse indicative of a UID; and
- detecting whether more than one UID having the selected UID byte was transferred if the number of positive pulses received exceeds the number expected for one UID.
20. A program storage device readable by a machine to execute program steps for identifying a contactless device having a unique identification code (UID) to a reader, the program steps comprising:
- receiving a UID call command from a reader;
- transferring at least one positive pulse indicative of the UID to the reader;
- receiving an anti-collision command and at least one UID value from a reader; and
- if the at least one UID value from the reader matches a corresponding portion of the UID of the card, transferring at least one positive pulse indicative of the UID to the reader.
21. A contactless card, comprising:
- a unique identifier comprising a plurality of bytes;
- a receiver for receiving an anti-collision command indicative of at least one desired identifier byte;
- a comparator in signal communication with the receiver for comparing the at least one desired identifier byte with at least one corresponding byte of the unique identifier; and
- a transmitter responsive to the comparator for transmitting the unique identifier as byte-wise positive pulses if the at least one desired identifier byte matches the at least one corresponding byte of the unique identifier.
22. A contactless card as defined in claim 21, further comprising an interpreter in signal communication with the receiver and the transmitter for recognizing a call command without anti-collision bytes and transmitting the unique identifier as byte-wise positive pulses in response thereto.
23. A contactless card as defined in claim 21 in combination with a reader, the reader comprising:
- a transmitter for transmitting an anti-collision command indicative of the at least one desired identifier byte;
- a receiver for receiving the unique identifier as byte-wise positive pulses if the at least one desired identifier byte matches the at least one corresponding byte of the unique identifier; and
- a detector in signal communication with the receiver for detecting a collision when the number of positive pulses exceeds the number of bytes in the unique identifier.
24. A contactless card reader, comprising:
- a transmitter for transmitting an anti-collision command indicative of at least one desired identifier byte;
- a receiver for receiving the unique identifier as byte-wise positive pulses if the at least one desired identifier byte matches the at least one corresponding byte of the unique identifier; and
- a detector in signal communication with the receiver for detecting a collision when the number of positive pulses exceeds the number of bytes in the unique identifier.
25. A contactless card reader as defined in claim 24, further comprising:
- a caller in signal communication with the transmitter for calling all contactless cards within a given range of the reader;
- a memory in signal communication with the receiver for storing in an ordered byte-wise manner all unique identifier bytes received in response to the caller; and
- an anti-collision commander in signal communication with the memory and the transmitter for issuing an anti-collision command to differentiate between multiple contactless cards.
26. A contactless card reader as defined in claim 25 wherein the caller calls all contactless cards within a given range of the reader at a periodic interval.
27. A contactless card reader as defined in claim 25 wherein the caller calls all contactless cards within a given range of the reader in response to a passive indication of at least one card.
28. A contactless card reader as defined in claim 25 wherein the memory is configured as a top matrix having a separate column and row for each byte of a unique identifier and having an additional row for each non-duplicate byte entry in any column.
29. A contactless card reader as defined in claim 28 wherein the detector fills in all remaining rightmost byte values for a row with the byte values of a unique identifier for a given card whenever a collision is not detected.
30. A contactless card reader as defined in claim 28 wherein the detector fills in one leftmost of the remaining byte values for a row with a commanded byte value of a unique identifier for a given card whenever a collision matches the existing byte and position.
31. An anti-collision coupling method for contactless cards, the method comprising:
- requesting that the cards transmit their unique identifiers, which each comprises a fixed plurality of bytes;
- receiving the unique identifiers simultaneously as byte-wise positive pulses;
- counting the received positive pulses; and
- determining that more than one card responded if the number of received positive pulses exceeds the fixed plurality of bytes.
32. An anti-collision coupling method as defined in claim 31, further comprising:
- initializing a byte position counter;
- setting a byte value to a byte value received in the first byte position of the unique identifiers; and
- forming an anti-collision command having the byte position counter and the byte value.
33. An anti-collision coupling method as defined in claim 32, further comprising:
- transmitting the anti-collision command comprising the byte position counter and at least one byte value to the cards;
- receiving the unique identifiers simultaneously as byte-wise positive pulses;
- counting the received positive pulses; and
- determining if more than one card responded if the number of received positive pulses exceeds the fixed plurality of bytes.
34. An anti-collision coupling method as defined in claim 33, further comprising, if more than one card responded:
- incrementing the byte position counter;
- setting the byte value to a byte value received in the incremented byte position of the unique identifiers;
- updating the anti-collision command by updating the byte position counter and adding the byte value; and
- repeating the steps of claim 33.
35. An anti-collision coupling method as defined in claim 33, further comprising, if only one card responded:
- determining that the reader has not called all of the unique identifier bytes corresponding to the current byte position counter;
- setting the byte value to another byte value received in the first byte position of the unique identifiers;
- updating the anti-collision command with the current byte value; and
- repeating the steps of claim 33.
36. An anti-collision coupling method as defined in claim 33, further comprising, if only one card responded:
- determining that the reader has called all of the unique identifier bytes corresponding to the current byte position counter; and
- activating the called cards corresponding to the received unique identifiers.
37. A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform program steps for anti-collision coupling of contactless cards, the program steps comprising:
- requesting that the cards transmit their unique identifiers, which each comprises a fixed plurality of bytes;
- receiving the unique identifiers simultaneously as byte-wise positive pulses;
- counting the received positive pulses; and
- determining that more than one card responded if the number of received positive pulses exceeds the fixed plurality of bytes.
38. A program storage device as defined in claim 37, the program steps further comprising:
- initializing a byte position counter;
- setting a byte value to a byte value received in the first byte position of the unique identifiers; and
- forming an anti-collision command having the byte position counter and the byte value.
39. A program storage device as defined in claim 38, the program steps further comprising:
- transmitting the anti-collision command comprising the byte position counter and at least one byte value to the cards;
- receiving the unique identifiers simultaneously as byte-wise positive pulses;
- counting the received positive pulses; and
- determining if more than one card responded if the number of received positive pulses exceeds the fixed plurality of bytes.
40. A program storage device as defined in claim 39, the program steps further comprising, if more than one card responded:
- incrementing the byte position counter;
- setting the byte value to a byte value received in the incremented byte position of the unique identifiers;
- updating the anti-collision command by updating the byte position counter and adding the byte value; and
- repeating the program steps of claim 39.
41. A program storage device as defined in claim 39, the program steps further comprising, if only one card responded:
- determining that the reader has not called all of the unique identifier bytes corresponding to the current byte position counter;
- setting the byte value to another byte value received in the first byte position of the unique identifiers;
- updating the anti-collision command with the current byte value; and
- repeating the program steps of claim 39.
42. A program storage device as defined in claim 39, the program steps further comprising, if only one card responded:
- determining that the reader has called all of the unique identifier bytes corresponding to the current byte position counter; and
- activating the called cards corresponding to the received unique identifiers.
Type: Application
Filed: Dec 13, 2005
Publication Date: Jul 6, 2006
Applicant:
Inventor: Yong-Wook Kim (Hwasung-si)
Application Number: 11/301,549
International Classification: G06K 7/08 (20060101);