Radio frequency identification readers, methods and computer program products for adjusting a query command slot-counter parameter Q

Patent metadata

Field	Value
Publication number	US-9405943-B2
Application number	US-201514679058-A
Country	US
Kind code	B2
Filing date	Apr 6, 2015
Priority date	Nov 26, 2008
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

RFID readers and methods for adjusting a query command slot-count parameter Q for use by radio frequency identification (RFID) tag reader in an RFID tag inventory round are provided. A method for adjusting a query command slot-count parameter Q for use by an RFID tag reader includes setting an initial value for Q for a first inventory round, issuing a query command to a population of RFID tags, and monitoring replies from the population of RFID tags. The value of Q is decreased by a first amount if no reply is received, and the value of Q is increased by a second amount different from the first amount if a tag collision reply is received.

First claim

The invention claimed is:

1. A method, comprising: setting, via a processor, an initial value for a query command slot-count parameter for a first inventory round; issuing, via the processor, a query command comprising the initial value for the query command slot-count parameter to a plurality of radio frequency identification tags; identifying, via the processor, replies from the plurality of radio frequency identification tags; and adjusting, via the processor, the initial value of the query command slot-count parameter for use in a second inventory round by a first amount if no reply is received for the query command that is issued, and by a second amount different from the first amount if a tag collision reply is received for the query command that is issued, wherein the second amount is a lesser of 1.0 and a value of a formula (0.1)*(Ave_Tcoll/Ave T_idle), wherein Ave_Tcoll is an average duration of a collided reply from the plurality of radio frequency identification tags, and wherein Ave_Tidle is an average duration of no reply from the plurality of radio frequency identification tags, wherein the Ave_Tcoll is in the range of 581 microseconds to less than 1456 microseconds.

2. The method of claim 1 , wherein the adjusting the initial value of the query command slot-count parameter by the first amount when no reply is received comprises decreasing the initial value of the query command slot-count parameter.

3. The method of claim 1 , wherein the adjusting the initial value of the query command slot-count parameter by the second amount when a tag collision reply is received comprises increasing the initial value of the query command slot-count parameter.

4. The method of claim 1 , wherein the first amount is less than the second amount.

5. A non-transitory computer readable medium storing a plurality of instructions which, when executed by a processor, causes the processor to perform operations, the operations comprising: setting an initial value for a query command slot-count parameter for a first inventory round; issuing a query command comprising the initial value for the query command slot-count parameter to a plurality of radio frequency identification tags; identifying replies from the plurality of radio frequency identification tags; and adjusting the initial value of the query command slot-count parameter for use in a second inventory round by a first amount if no reply is received for the query command that is issued, and by a second amount different from the first amount if a tag collision reply is received for the query command that is issued, wherein the second amount is a lesser of 1.0 and a value of a formula (0.1)*(Ave_Tcoll/Ave_Tidle), wherein Ave_Tcoll is an average duration of a collided reply from the plurality of radio frequency identification tags, and wherein Ave_Tidle is an average duration of no reply from the plurality of radio frequency identification tags, wherein the Ave_Tcoll is in the range of 581 microseconds to less than 1456 microseconds.

6. The non-transitory computer readable medium of claim 5 , wherein the adjusting comprises decreasing the initial value of the query command slot-count parameter for use in the second inventory round by the first amount when no reply is received for the query command that is issued.

7. The non-transitory computer readable medium of claim 5 , wherein the adjusting comprises increasing the initial value of the query command slot-count parameter for use in the second inventory round by the second amount when a tag collision reply is received for the query command that is issued, wherein the first amount is less than the second amount.

8. The non-transitory computer readable medium of claim 5 , wherein the first amount is less than the second amount.

9. A radio frequency identification reader, comprising: a processor of a radio frequency identification controller; a transceiver coupled to the radio frequency identification controller; a radio frequency antenna coupled to the transceiver; wherein the radio frequency antenna transmits a command received from the processor of the radio frequency identification controller via the transceiver and receives responses from a plurality of radio frequency identification tags; and wherein the processor of the radio frequency identification controller performs operations, the operations comprising: setting an initial value for a query command slot-count parameter for a first inventory round; issuing a query command comprising the initial value for the query command slot-count parameter to the plurality of radio frequency identification tags; identifying replies from the plurality of radio frequency identification tags; and adjusting the initial value of the query command slot-count parameter for use in a second inventory round by a first amount if no reply is received for the query command that is issued, and by a second amount different from the first amount if a tag collision reply is received for the query command that is issued, wherein the second amount is a lesser of 1.0 and a value of a formula (0.1)*(Ave_Tcoll/Ave_Tidle), wherein Ave_Tcoll is an average duration of a collided reply from the plurality of radio frequency identification tags, and wherein Ave_Tidle is an average duration of no reply from the plurality of radio frequency identification tags, wherein the Ave_Tcoll is in the range of 581 microseconds to less than 1456 microseconds.

10. The radio frequency identification reader of claim 9 , wherein the controller decreases the initial value of the query command slot-count parameter when no reply is received.

11. The radio frequency identification reader of claim 9 , wherein the controller increases the initial value of the query command slot-count parameter when a tag collision reply is received.

12. The radio frequency identification reader of claim 9 , wherein the first amount is less than the second amount.

13. The radio frequency identification reader of claim 9 , further comprising:
a memory for storing the initial value of the query command slot-count parameter and subsequent values of the query command slot-count parameter.

Assignees

• At & T Ip I Lp

Inventors

• Daneshmand Mahmoud
• Wang Chonggang

Classifications

• H04Q2209/47

  using RFID associated with sensors · CPC title

• G06K7/10029 Primary

  the collision being resolved in the time domain, e.g. using binary tree search or RFID responses allocated to a random time slot · CPC title

• G06K17/0022

  arrangements or provisions for transferring data to distant stations, e.g. from a sensing device ("transfer between computer elements G06F13/00 "; data-transmission H04L) · CPC title

• H04W74/0816

  with collision avoidance · CPC title

• G06K7/0008 Primary

  General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer · CPC title