Method for selecting one or more transponders

• US 20050231327A1
• Filed: 04/13/2005
• Published: 10/20/2005
• Est. Priority Date: 04/14/2004
• Status: Abandoned Application

• Current Assignee: Atmel Germany GmbH (Microchip Technology Incorporated)
• Original Assignee: Atmel Germany GmbH (Microchip Technology Incorporated)
• Inventors: Friedrich, Ulrich, Pangels, Michael
• Application Number:
  US11/104,438
• Publication Number:
  US 20050231327A1
• Time in Patent Office: Days
• US Class Current: 340/10.200
• CPC Class Codes: G01S 13/75 using transponders powered from received waves, e.g. using passive transponders , or using passive reflectors
• 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 7/10059 transponder driven

Abstract

A method and system is provided for selecting one or more transponders from a plurality of transponders by a base station, in which a random number generated in a given transponder determines a point in time when the transponder in question transmits an identification to the base station. The base station transmits a selection command, then, in order to determine whether at least one transponder is addressed by the selection command, all addressed transponders substantially simultaneously transmit an identification to the base station at a first point in time, and if more than one transponder is addressed, each addressed transponder transmits its identification to the base station at least once more at an additional point in time. The additional point in time being determined by the value of the random number generated or to be generated in the relevant transponder.

Claims

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

transmitting, by the base station, a selection command; and

determining whether at least one transponder is addressed by the selection command in that all addressed transponders substantially simultaneously transmit an identification to the base station at a first time point,

wherein if more than one transponder is addressed, each addressed transponder transmits its identification to the base station at least once more at an additional point in time on the basis of a generated random number that each transponder generates, the generated random number determining a time point when the transponder transmits an identification to the base station

2. The method according to claim 1, wherein a transponder whose random number corresponds to the first time point repeatedly generates a new random number such that the new random number no longer corresponds to the first time point, and wherein the additional time point is determined using the new generated random number.

3. The method according to claim 1, wherein possible values of the generated random number in given transponder correspond to the time points after an initial time point.

4. The method according to claim 1, wherein, in a slotted ALOHA selection method, the first time point lies within a slot, in particular a first slot, after the selection command.

5. The method according to claim 4, wherein a transponder whose random number corresponds to the slot of the first time point repeatedly generates a new random number until the new random number no longer corresponds to the slot of the first time point.

6. The method according to claim 4, wherein the random numbers are assigned to slots that follow the initial slot after the selection command.

7. The method according to claim 2 or 5, wherein the regeneration of the new random number is terminated upon receipt of a synchronization mark that is transmitted by the base station.

8. The method according to claim 1, wherein the one or more transponders are backscatter-based transponders.

9. The method according to claim 1, wherein the selection method is based on an ALOHA method or a slotted ALOHA.

10. A transmission system comprising:

a plurality of transponders; and

a base station for transmitting a selection command to the plurality of transponders, the selection command including a group select command for addressing a subset of transponders from the plurality of transponders,

wherein each of the subset of transponders generates a random number that indicates a time slot for transmitting to the base station,

wherein each of the subset of transponders transmit to the base station an identification during a first time slot, and

wherein, if a transponder of the subset of transponders generated a random number indicating transmission during the first time slot, that transponder repeatedly generates a new random number until the new random number indicates a time slot that is different from the first time slot.