Data format for efficient encoding and access of multiple data items in RFID tags

• US 7,822,944 B2
• Filed: 05/29/2007
• Issued: 10/26/2010
• Est. Priority Date: 05/26/2006
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Schuessler, Frederick
• Primary Examiner(s): Patel; Hetul
• Assistant Examiner(s): SCHNEE, HAL W
• Application Number:
  US11/806,053
• Publication Number:
  US 20070276985A1
• Time in Patent Office: 1,246 Days
• Field of Search: 711/207, 711/217, 711/E12.015, 711/E12.034, 340/10.1
• US Class Current: 711/217
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Abstract

Systems and methods for optimizing random access retrieval of a requested data item in a radio frequency identification (RFID) tag are provided. During random access retrieval, a first read of a memory bank in the RFID tag is performed. The first read providers a set of identifier indices stored in a packed object in the memory bank of the RFID tag and a length of the packed object. A determination is then made whether a retrieved identifier index represents the requested data item to be retrieved. A second read of the memory bank, accessing the portion of the memory bank including the data items, is then performed. The location of the data item in the packed object may optionally be determined prior to the second read.

Claims

1. A method for random access retrieval of a requested data item stored in a Radio Frequency Identification (RFID) tag, comprising:

determining a first read size comprising at least one of (a) a smallest first read such that the first read has a high likelihood of providing all of bits needed to establish presence or absence of target identifiers with a low likelihood of a read-overrun error response from the RFID tag or (b) a largest first read such that the first read will incur an acceptably-low re-transmit rate due to signal-to-noise ratio with a low likelihood of a read-overrun error response from the RFID tag;

performing the first read of a memory bank in the RFID tag to retrieve a set of identifier indices stored in a packed object in the memory bank and a length of the packed object, wherein the packed object comprises;

a length section including an indication of a number of identifiers in the packed object,

an identifier section including the set of identifier indices representing an identifier for the requested data item contained within the packed object, and

a data section encoding a data portion associated with the requested data item included in the identifier section;

determining whether a retrieved identifier index in the set of identifier indices represents the requested data item;

if the retrieved identifier index represents the requested data item, performing a second read of the memory bank, wherein the second read accesses the data section of the memory bank including the requested data item; and

receiving data based on the second read, wherein the received data are processed, transmitted to a remote server, or combinations thereof.

2. The method of claim 1, wherein the RFID tag comprises a Gen 2 tag.

3. The method of claim 1, further comprising maintaining statistics related to a probability of overruns among a population of RFID tags and utilizing the statistics in determining the size of the first read.

4. The method of claim 1, further comprising determining a location of the requested data item within the packed object based on either a memory format of the RFID tag if each data element in the packed object is independently encoded or a virtual random access if two or more data elements are concatenated and encoded as a single unit.

5. The method of claim 1, further comprising decoding an alphanumeric subsection of the packed object.

6. The method of claim 1, further comprising encoding the packed object in the memory bank.

7. A method for random access retrieval of a requested data item stored in a Radio Frequency Identification (RFID) tag, comprising:

determining a first read size comprising at least one of (a) a smallest first read such that the first read has a high likelihood of providing all of bits needed to establish presence or absence of target identifiers with a low likelihood of a read-overrun error response from the RFID tag or (b) a largest first read such that the first read will incur an acceptably-low re-transmit rate due to signal-to-noise ratio with a low likelihood of a read-overrun error response from the RFID tag;

performing the first read of a memory bank in the RFID tag to retrieve a set of identifier indices stored in a packed object in the memory bank and a length of the packed object, wherein the packed object comprises;

a length section including an indication of a number of identifiers in the packed object,

an identifier section including the set of identifier indices representing an identifier for the requested data item contained within the packed object, and

a data section encoding a data portion associated with the requested data item included in the identifier section;

determining whether a retrieved identifier index in the set of identifier indices represents the requested data item;

determining a location of the requested data item within the packed object in the memory bank based on information provided in the first read if a retrieved identifier index represents the requested data item;

if the retrieved identifier index represents the requested data item, performing a second read of the memory bank, wherein the second read accesses the data section of the memory bank including the requested data item; and

receiving data based on the second read, wherein the received data are processed, transmitted to a remote server, or combinations thereof.

8. The method of claim 7, wherein the RFID tag comprises a Gen 2 tag.

9. The method of claim 7, further comprising maintaining statistics related to a probability of overruns among a population of RFID tags and utilizing the statistics in determining the size of the first read.

10. The method of claim 7, wherein determining the location of the requested data item within the packed object is based on either a memory format of the RFID tag if each data element in the packed object is independently encoded or a virtual random access if two or more data elements are concatenated and encoded as a single unit.

11. The method of claim 7, further comprising decoding an alphanumeric subsection of the packed object.

12. The method of claim 7, further comprising encoding the packed object in the memory bank.