RFID tag system with block coding, such as space-time block coding

• US 8,508,369 B2
• Filed: 03/29/2007
• Issued: 08/13/2013
• Est. Priority Date: 09/01/2006
• Status: Active Grant

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: Maltseff, Paul A.
• Primary Examiner(s): Nguyen, Tai T
• Assistant Examiner(s): NWUGO, OJIAKO K
• Application Number:
  US12/446,445
• Publication Number:
  US 20100277318A1
• Time in Patent Office: 2,329 Days
• Field of Search: 340 51- 55, 340 101- 105, 3405721-5729, 235375-385, 455/101
• US Class Current: 340/572.1
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: H04B 5/77 for interrogation
• CPC Class Codes: H04B 7/0667 of delayed versions of same signal using space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04B 7/12 Frequency diversity

Abstract

An apparatus for use in an RFID data collection system includes an antenna portion for wirelessly exchanging signals and a memory portion for storing RFID data. A signal processing portion is coupled among the antenna portion and the memory portion. The signal processing portion is configured to receive RFID data and to at least encode or decode the received RFID data via space-time block codes (STBC). For example, an RFID tag employs two spatially separated antennas and circuitry for transmitting to an RFID reader data stored in tag memory as STBC encoded data. Other configurations are also disclosed.

Claims

1. An RFID tag, comprising:

a tag substrate;

at least first and second spatially separated antennas formed on the substrate;

a memory received by the substrate and storing tag data;

processing circuitry;

first and second modulation circuitries corresponding to the first and second spatially separated antennas,

wherein the processing circuitry and first and second modulation circuitries are received by the substrate and coupled among the first and second antennas and the memory,

wherein the processing circuitry and first and second modulation circuitries are configured to;

receive the tag data; and

generate a protocol communication based on the tag data,

wherein the protocol communication indicates that the RFID tag is configured to use space-time block coding (STBC),

produce first and second blocks of related output symbols,

wherein the first block of output symbols includes at least a first pair of symbols and, the second block of output symbols includes at least a second pair of symbols, and

wherein at least some of the symbols in the second block of output symbols is a negation and/or complex conjugate of a related symbol in the first block of output symbols; and

wherein the first antenna transmits the first block of symbols, and the second antenna transmits the second block of symbols.

2. The RFID tag of claim 1 wherein the processing circuitry is further configured to:

transmit the protocol communication; and

enter an STBC communications mode.

3. The RFID tag of claim 1 wherein the first and second pairs of symbols are respectively x₁, −

x₂* and x₂, x₁*, or x₁, x₂* and x₂, −

x₁*, or x₁, x₂*i and x₂, −

x₁*i, or x₁, −

x₂*i and x₂, x₁*i.

4. The RFID tag of claim 1 wherein the first pair of symbols is x₁, x₂ and the second pair of symbols is −

x₂*, x₁* or x₂*, −

x₁* or x₂*i, −

x₁*i or −

x₂*i, x₁*i.

5. The RFID tag of claim 1 wherein the RFID tag is a passive tag.

6. The RFID tag of claim 1 wherein the processing and modulation circuitries are further configured to transmit the first block using a first frequency, and transmit the second block using a second frequency.

7. An RFID reader, comprising:

antenna means for wirelessly exchanging signals

wherein the signals include a protocol communication and first and second blocks of symbols and,

wherein the antenna means includes at least first and second spatially separated antennas for concurrently receiving the first and second blocks of symbols, respectively;

a memory means for storing data; and

processing and circuitry means, coupled among the antenna means and the memory means, for;

processing the protocol communication,

wherein the protocol communication indicates that an RFID tag is configured to use space-time block coding (STBC), and

concurrently decoding the first and second blocks of symbols to extract RFID tag data stored in the RFID tags,

wherein the RFID tag data is encoded using STBC.

8. The RFID reader of claim 7 wherein the processing and circuitry means further includes means for transmitting data using STBC.

9. The RFID reader of claim 7 wherein the processing and circuitry means further comprises means for entering an STBC communications mode responsive to said processing the protocol communication.

10. A semiconductor device for use in an RFID tag, the device comprising:

encoder circuitries configured to receive incoming tag data stored by the RFID tag and convert the tag data into blocks of multiple symbols,

wherein the encoder circuitry is further configured to generate encoded sequences of symbols in at least some of the blocks, and,

wherein the generated encoded sequences include selectively negating symbols, selectively complex conjugating symbols, and selectively complex conjugating symbols;

processing circuitry configured to receive at least some of the incoming tag data and generate a protocol communication based on the incoming tag data,

wherein the protocol communication indicates that the RFID tag is configured to use diversity in the transmitted encoded sequences based on time diversity, coding or frequency diversity; and

an output portion for outputting the protocol communication and the blocks of multiple symbols to be transmitted by the RFID tag,

wherein the RFID tag includes at least two spatially separated transmitting antennas,

wherein each of the at least two transmitting antennas transmits a differently encoded sequence, and

wherein the RFID tag creates further diversity in the transmitted encoded sequences based on time diversity, coding or frequency diversity.

11. The semiconductor device for use with an RFID tag of claim 10 wherein each block of multiple symbols comprises two symbols.

12. The semiconductor device for use with an RFID tag of claim 10 wherein the encoder circuitries are further configured to provide time diversity by replicating symbols among blocks of symbols.

13. The semiconductor device for use with an RFID tag of claim 10, further comprising memory, coupled to the encoder circuitry, for storing the tag data, and analog circuitry coupled among the antennas and the output portion for converting the blocks of multiple symbols into signals for transmission by the antennas.

14. An apparatus for use in an RFID data collection system, the apparatus comprising:

an antenna portion for wirelessly exchanging signals including a protocol communication and first and second blocks of symbols,

wherein the antenna means includes at least first and second spatially separated antennas for concurrently transmitting or receiving the first and second blocks of symbols, respectively;

a memory portion for storing RFID data; and

a signal processing portion coupled among the antenna portion and the memory portion, wherein the signal processing portion is configured to;

process or generate the protocol communication,

wherein the protocol communication indicates that an RFID tag is configured to use space-time block coding (STBC),

enter a STBC communications mode responsive to said processing or generating the protocol communication, and

receive RFID data and to at least encode or decode the received RFID data via space-time block codes.

15. The apparatus of claim 14 wherein the apparatus is an RFID tag, and wherein the signal processing portion is configured to encode the received RFID data via space-time block codes.

16. The apparatus of claim 14 wherein the apparatus is an RFID tag reader, and wherein the signal processing portion is configured to decode the received RFID data via space-time block codes.

17. A non-transitory computer-readable medium having programming instructions stored thereon, wherein the programming instructions, when executed by at least one device, cause the at least one device to:

process a protocol communication initiated by an RFID tag,

wherein the protocol communication indicates that an RFID tag is configured to use space-time block coding (STBC);

enter a STBC communications mode responsive to processing the protocol communication;

receive the tag data from the RFID tag, wherein the tag data is encoded using STBC;

decode the space-time block encoded tag data; and

,

output the decoded space-time block encoded tag data for data storage or automated data processing.

18. The non-transitory computer-readable medium of claim 17 wherein the programming instructions, when executed by the at least one device, further cause the device to initially communicate with the RFID tag to determine whether the RFID tag can provide space-time block encoded RFID tag data from at least first and second spatially separated antennas formed on the substrate.

19. A wireless data collection system comprising:

an RFID tag having;

at least first and second spatially separated antennas to transmit blocks of symbols;

an encoder configured to generate from incoming symbols a first block of output symbols for transmission by the first antenna, and a second block of output symbols for transmission by the second antenna,

wherein the second block of output symbols is related to the first block of output symbols;

wherein each one of the output symbols in the first block of output symbols is related, as a set of symbols, with one of the output symbols in the second block of output symbols, and

wherein one symbol in each set of symbols is a negation, complex conjugate, or a negative complex conjugate of the other symbol in the set of symbols; and

,

an RFID reader module having at least one antenna and configured to exchange wireless signals with the RFID tag;

wherein at least the RFID tag or the RFID reader is configured to transmit blocks of symbols, wherein the signals have two or more diversities selected from the group of;

space diversity, time diversity, frequency diversity and coding diversity.

20. The wireless data collection system of claim 19 wherein the both the RFID tag and the RFID reader module have N number of antennas, where N is greater than or equal to three.

21. The wireless data collection system of claim 19, the RFID tag further having:

a memory storing tag data; and

processing circuitry and modulation circuitries corresponding to the first and second spatially separated antennas, the processing circuitry and modulation circuitries coupled among the first and second antennas and the memory.

22. The wireless data collection system of claim 21, wherein the processing circuitry and modulation circuitries are further configured to:

receive the tag data; and

generate a protocol communication based on the tag data,

wherein the protocol communication indicates that the RFID tag is capable of using space-time block coding (STBC).