Method for selecting one or several transponders

• US 20050083178A1
• Filed: 10/19/2004
• Published: 04/21/2005
• Est. Priority Date: 10/21/2003
• Status: Active Grant

• Current Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Original Assignee: Atmel Germany GmbH (Microchip Technology Incorporated)
• Inventors: Friedrich, Ulrich
• Granted Patent: US 7,312,692 B2
• Time in Patent Office: Days
• US Class Current: 340/10.200
• 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

In a method for selecting, by a base station, one or more transponders out of a plurality of transponders, selection steps are performed at least at two selection levels or stages. The base station controls all selection steps at the first and second level. The first selection level includes: each transponder generates a random transponder number, the base station generates numbered time slots, each transponder transmits a marker if and when its random transponder number coincides with a time slot number. When a single transponder random number coincides with a time slot number the respective transponder is selected by the base station. If more than one transponder random numbers coincide with a time slot number the second selection procedure is performed at a second selection level as a stochastic or a deterministic or a mixed stochastic-deterministic selection procedure.

Claims

1. A method for selecting by a base station at least one transponder out of a plurality of transponders, said method comprising the following steps a) to e) performed as a first selection procedure at a first selection level:

a) controlling by said base station (BS) a first selection procedure,

b) producing by each transponder (TR1, TR2, . . . ) a random transponder number,

c) generating in said base station (BS) numbered time slots so that each time slot has a time slot number,

d) transmitting by each transponder a marker to said base station during a time slot having a respective time slot number coinciding with said respective random transponder number,

e) selecting that transponder which was the only transponder transmitting during said coinciding time slot,

f) checking, at a second selection level, whether more transponders than one have transmitted a respective marker in the same time slot to provide a respective collision signal, and

g) performing, at said second selection level under the control of said base station and in response to said collision signal a second selection procedure as any one of a stochastic, a deterministic, and a mixed stochastic-deterministic selection procedure.

2. The method of claim 1, wherein said second selection procedure is performed as a stochastic ALOHA-selection procedure.

3. The method of claim 2, wherein said stochastic ALOHA-selection procedure is a time slot based selection procedure.

4. The method of claim 1, wherein said second selection procedure is performed as a deterministic binary search procedure.

5. The method of claim 1, further comprising performing said second selection procedure at said second selection level by the following substeps:

h1) generating in each of said plurality of transponders a respective transponder identification bit sequence,

h2) transmitting by said base station in a bit-by-bit fashion a selection bit sequence to said plurality of transponders,

h3) comparing, in accordance with a predeterminable comparison criterion, in each respective transponder said selection bit sequence with a respective identification bit sequence to provide a comparing result in the form of a selected bit,

h4) allocating a logic value to said selected bit, and

h5) selecting a respective transponder in accordance with said logic value of said selected bit.

6. The method of claim 5, further comprising generating said identification bit sequence in each transponder as a bit sequence that includes a random bit sequence.

7. The method of claim 1, further comprising retransmitting a received marking that includes one or more markers, at least partially from said base station to said transponders for checking whether more than one transponder has transmitted a marker within the same time slot, comparing in each transponder whether a retransmitted marking is matching the marker transmitted by the respective transponder, and excluding any transponder from any further selection procedure if there is no matching within said time slot.

8. The method of claim 1, further comprising encoding said marker for said transmitting of step d) in accordance with a 3-phase-1 type encoding.

9. The method of claim 1, further comprising generating said random transponder number of step b) in said first selection level by means of a clocked, linear shift register (SR) that is feedback controlled, and deactivating a clock signal for said shift register during phases of an increased power input of said shift register compared to an average power input of said shift register.

10. The method of claim 9, further comprising generating any random transponder number as a random number bit sequence.

11. The method of claim 1, further comprising generating any random transponder number produced during said second selection procedure at said second selection level by means of a clocked, linear shift register (SR) that is feedback controlled, and deactivating a clock signal to said shift register during phases of an increased power input to said shift register compared to an average power input to said shift register.

13. The method of claim 9, comprising deactivating said clock signal during a data transmission from said base station to any one of said plurality of transponders (TR1, TR2, TR3).

14. The method of claim 11, comprising deactivating said clock signal during a data transmission from said base station to any one of said plurality of transponders (TR1, TR2, TR3).

15. The method of claim 13, further comprising deactivating said shift register by means of a logic gate connected between a clock signal generator and said shift register.

16. The method of claim 14, further comprising deactivating said shift register by means of a logic gate connected between a clock signal generator and said shift register.

17. The method of claim 1, further comprising generating said random transponder number of step (b) of the first selection level and any second random transponder number of said second selection level by means of a clocked, linear shift register (SR) that is feedback controlled.

18. The method of claim 17, wherein said random transponder number of said second selection level is a random number bit sequence.

19. The method of claim 17, further comprising allocating a first portion of a number of bits of said shift register to said random transponder number of said first selection level, and allocating a remainder portion of shift register bits to said second random transponder number of said second selection level.

20. The method of claim 17, further comprising generating said random transponder number of said first selection level by means of a shift register and storing said random number in a memory, then generating said second random transponder number in said same shift register and storing said second random transponder number separately from said random transponder number of said first selection level.

21. The method of claim 20, further comprising clocking said shift register with a larger clock frequency for generating said first random transponder number and operating said shift register with a smaller clock frequency, relative to said first clock frequency for generating said second random number.

22. The method of claim 1, further comprising generating an additional random transponder number in response to a recognition that a second random transponder number of said second selection level is inadequate, wherein said second random transponder number is formed by a logic linking of transponder specific data with a random transponder number of said second selection level.

12. The method of clam 11, further comprising generating any random transponder number as a random number bit sequence.