Method for selecting one or more transponders

• US 7,336,154 B2
• Filed: 07/30/2004
• Issued: 02/26/2008
• Est. Priority Date: 08/01/2003
• Status: Expired due to Fees

• Current Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Original Assignee: Atmel Germany GmbH (Microchip Technology Incorporated)
• Inventors: Friedrich, Ulrich
• Primary Examiner(s): Zimmerman; Brian
• Assistant Examiner(s): NGUYEN, NAM V
• Application Number:
  US10/903,721
• Publication Number:
  US 20050024186A1
• Time in Patent Office: 1,306 Days
• Field of Search: 340/10.2, 340/10.4, 340/10.41, 340/10.42, 340/10.3, 340/10.31, 340/10.5, 340/10.1, 235/435, 342/42, 342/44, 342/118, 342126-128
• US Class Current: 340/10.2
• CPC Class Codes: G06K 17/00 Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations
• 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
• CPC Class Codes: G06K 7/10049 binary tree

Abstract

One or more transponders are selected by a base station out of a plurality of transponders. For this purpose an identification bit sequence (IB) that is or includes a random number bit sequence (ZB) is made available in the respective transponder and the base station transmits in a bit-by-bit fashion a selection bit sequence (AB) to the transponders. These sequences (IB or ZB) and (AB) are compared bit-by-bit in the respective transponder. The comparing is performed by way of a predeterminable comparing criterion to provide a comparing result in the form of a selection bit to which a bit value is assigned. The selection is then made depending on the bit value of the selection bit of the respective transponder.

Claims

1. A method of selecting one or more transponders from a plurality of transponders by a base station, said method comprising the following selection steps:

a) generating, respectively in each respective transponder of said plurality of transponders, a respective random number bit sequence comprising random bit values;

b) providing, respectively in each said respective transponder, an identification bit sequence comprising said random number bit sequence of said respective transponder;

c) transmitting bit-by-bit a selection bit sequence comprising selection bit values, from said base station to said plurality of transponders;

d) comparing bit-by-bit, respectively in each said respective transponder, corresponding bits of said identification bit sequence of said respective transponder with corresponding bits of said selection bit sequence, wherein said comparing is carried out using a predetermined comparison criterion to provide a comparison result;

e) in each said respective transponder, respectively allocating to a transponder selecting indicator bit for said respective transponder a transponder selecting indicator bit value according to and depending on said comparison result;

f) respectively selecting one or more of said transponders in response to and depending on said transponder selecting indicator bit value allocated to said transponder selecting indicator bit of each said transponder respectively;

g) prior to said respective bit-wise comparing of said corresponding bit of said identification bit sequence of said respective transponder with said corresponding bit of said selection bit sequence in said step d), transmitting a respective bit value of said respective corresponding bit of said identification bit sequence from said respective transponder to said base station; and

h) generating at least one of said selection bit values of said selection bit sequence in said base station in response to and depending on at least one said respective bit value of said respective corresponding bit of said identification bit sequence received by said base station from said respective transponder.

2. The method of claim 1, further comprising transmitting said predetermined comparison criterion from said base station to said transponders.

3. The method of claim 2, further comprising varying said comparison criterion dependent on a respective bit position of bits of said identification bit sequence and of bits of said selection bit sequence that are to be compared with one another.

4. The method of claim 1, further comprising selecting said predetermined comparison criterion as an arithmetic operator.

5. The method of claim 4, wherein said arithmetic operator is selected as any one of a larger-than operator, a smaller-than operator and an equal-to operator.

6. The method of claim 1, wherein said identification bit sequence comprises, in addition to said random number bit sequence, a static bit sequence portion which is respectively assigned to said transponders when said transponders are manufactured.

7. The method of claim 1, further comprising repeatedly performing said selection steps in successive selection processes, and omitting from a subsequent one of said selection processes transponders that have been selected in a preceding one of said selection processes.

8. The method of claim 7, further comprising generating in a respective one of said transponders still participating in said subsequent selection process, a new random number bit sequence and including said new random number bit sequence in said identification bit sequence.

9. The method of claim 1, further comprising encoding said random bit values of said random number bit sequence by assigning a time duration t0 to a random bit value “

0” and

assigning a time duration t1 to a random bit value “

1”

.

10. The method of claim 9, wherein said encoding of said random bit values is performed in said transponders.

11. The method of claim 9, further comprising encoding said selection bit values of said selection bit sequence by assigning a time duration T0 to a selection bit value “

0” and

assigning a time duration T1 to a selection bit value “

1”

, wherein T0 is greater than t0 and t1, and wherein T1 is greater than t0 and t1.

12. The method of claim 11, wherein said encoding of said selection bit values is performed in said base station.

13. The method of claim 11, wherein said encoding of said selection bit values is represented by a time duration of a time slot between two synchronization markers.