Method of Reading Data From Transponders Through a Reader, a Transponder, and a Reader

• US 20080272891A1
• Filed: 10/24/2006
• Published: 11/06/2008
• Est. Priority Date: 10/25/2005
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Amtmann, Franz
• Granted Patent: US 8,253,540 B2
• Time in Patent Office: Days
• US Class Current: 340/10.1
• 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 7/10039 interrogator driven, i.e. synchronous
• CPC Class Codes: G06K 7/10059 transponder driven

Abstract

A method of reading data (DAT1 . . . DAT4) from transponders (T1 . . . T4) by means of a reader device (RD) during a number (N) of time slots (TS) is disclosed, wherein the seizure of said time slots (TS) by the transponders (T1 . . . T4) is observed in both the reader device (RD) and the transponders (T1 . . . T4). A reorganization (REORG) is performed in dependence on said seizure, wherein both the reader device (RD) and the transponders (T1 . . . T4) choose a new number (N) of time slots (TS). In addition, the transponders (T1 . . . T4) select one of the new time slots (TS) in which to send data (DAT1 . . . DAT4) back to the reader device (RD) so as to adapt the system'"'"'s capacity to the real demands. Preferably, said reorganization (REORG) takes place without communication between the reader device (RD) and the transponders (T1 . . . T4). The invention further relates to a transponder (T1 . . . T4) and to a reader device (RD) for implementing the inventive method.

Claims

1. Method of reading data from transponders by means of a reader device during a number of time slots, comprising the steps of:

observing the seizure of said timeslots in both the reader device and the transponders, and

performing a reorganization in dependence on said seizure, wherein a new number of time slots is chosen in both the reader device and the transponders, and in the transponders additionally one of the new time slots is selected in which to send data back to the reader device.

2. Method as claimed in claim 1, wherein only those transponders perform said reorganization which did not transmit data to the reader device before said reorganization.

3. Method as claimed in claim 1, wherein only those transponders perform said reorganization whose data were not correctly received in the reader device before said reorganization.

4. Method as claimed in claim 1, wherein a transponder selects a new time slot only on the basis of a certain probability.

5. Method as claimed in claim 1, wherein said reorganization is performed without exchanging any information on said reorganization between said reader device and said transponders.

6. Method as claimed in claim 1, wherein both the reader device and the transponders count empty time slots, and wherein said reorganization is performed with a smaller new number of time slots if the number of said empty time slots exceeds a predefined limit.

7. Method as claimed in claim 6, wherein the counter of empty time slots in a transponder is increased upon receipt of a close slot command which is sent by the reader device within a waiting time after a preceding command, which waiting time is used by the reader device in waiting for data from the transponders.

8. Method as claimed in claim 1, wherein both the reader device and the transponders count data collisions between two or more transponders, and wherein said reorganization is performed with a greater new number of time slots if the number of said data collisions exceeds a predefined limit.

9. Method as claimed in claim 8, wherein the counter of data collisions in a transponder is increased upon receipt of a close slot command which is sent by the reader device after a waiting time following a preceding command, which waiting time is used by the reader device in waiting for data from the transponders.

10. Method as claimed in claim 1, wherein transmission channels are used instead of time slots, and wherein said transmission channels are formed by time slot, in which data are transmitted in addition in different frequency bands and/or with the use of different code sequences.

11. Method as claimed in claim 1, wherein a probability parameter additional to the number of time slots or instead of the number of time slots is chosen in both the reader device and the transponders during a reorganization, and wherein additionally a time slot in which to send data back to the reader device is selected in the transponders with a certain probability that is in accordance with said probability parameter.

12. Transponder designed to send data to a reader devices during a number of time slots, comprising:

means for observing a seizure of said time slots by other transponders, and

means for performing a reorganization in dependence on said seizure, wherein a new number of time slots is chosen, and in addition one of the new time slots is selected in which to send data back to the reader device.

13. Transponder as claimed in claim 12, additionally comprising:

a counter for counting empty time slots and means for increasing said counter upon receipt of a close slot command sent by the reader device within a waiting time after a preceding command, which waiting time is used by the reader device in waiting for data from the transponders and/or

a counter for counting data collisions between two or more transponders, and means for increasing said counter upon receipt of a close slot command sent by the reader devices after a waiting time following a preceding command, which waiting time is used by the reader device in waiting for data from the transponders.

14. Reader device designed to read data from transponders during a number of time slots, comprising:

means for observing the seizure of said time slots,

means for performing a reorganization in dependence on said seizure, wherein a new number of time slots is chosen without exchanging any information on said reorganization with said transponders.