System and method for allowing multiple RFID reader devices to read RFID tags without collision

• US 8,350,676 B2
• Filed: 09/12/2008
• Issued: 01/08/2013
• Est. Priority Date: 09/18/2007
• Status: Expired due to Fees

• Current Assignee: Emw Co., Ltd.
• Original Assignee: Emw Co., Ltd.
• Inventors: Ryou, Byung Hoon, Sung, Won Mo, Choi, Bong Suk, Kim, You Ho, Seo, Seung Up, Jang, Young Soo, Na, Ha Sun
• Primary Examiner(s): Wu, Daniel
• Assistant Examiner(s): MA, KAM WAN
• Application Number:
  US12/678,488
• Publication Number:
  US 20100201494A1
• Time in Patent Office: 1,579 Days
• Field of Search: 340/10.2, 455/447, 455450-453, 455/464, 455509-515, 370329-338
• US Class Current: 340/10.2
• 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 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas
• CPC Class Codes: H04W 74/00 Wireless channel access

Abstract

Provided are an RFID operating system and an RFID system operating method for allowing multiple RFID readers to read tags without collision. The RFID system operating method includes the steps of grouping RFID readers spaced apart by more than a spacing distance capable of avoiding collision between RFID readers into a single group to determine at least one group, classifying RPM readers included in each group into at least one sub-group based on a read time of each RFID reader, and driving the RFID readers such that RPM readers belonging to at least two different sub-groups that do not collide with each other simultaneously operate. According to the present invention, switching is performed sub-group by sub-group to reduce the number of switching operations and sub-groups can simultaneously operate to decrease a read time.

Claims

1. A method of operating an RFID (Radio Frequency Identification) system including multiple RFID readers, comprising:

grouping RFID readers spaced apart by more than a spacing distance to avoid collision between RFID readers into a single group to determine at least one group;

classifying RFID readers included in each group into at least one sub-group based on a read time of each RFID reader; and

driving the RFID readers such that RFID readers belonging to at least two different sub-groups that do not collide with each other simultaneously operate;

wherein driving the RFID readers comprises;

allowing RFID readers belonging to a first group to start to operate;

detecting a first sub-group that finishes the operation thereof among sub-groups included in the first group;

determining a second sub-group which belongs to a second group different from the first group and includes RFID readers that collide with RFID readers belonging to the first sub-group; and

allowing the RFID readers belonging to the second sub-group to operate after the RFID readers belonging to the first sub-group finish the operations thereof.

2. The method according to claim 1, wherein determining the at least one group comprises:

selecting a reference RFID reader;

selecting an RFID reader spaced apart from the reference reader by more than the spacing distance; and

excluding the selected RFID reader from the corresponding group when a distance between the selected RFID reader and an RFID reader included in the group other than the reference RFID reader is shorter than the spacing distance.

3. The method according to claim 1, wherein determining the group comprises determining a distance between the RFID readers based on the coordinates of the RFID readers.

4. The method according to claim 1, wherein the spacing distance is determined based on readable distances of the RFID readers.

5. The method according to claim 1, wherein determining the second sub-group is performed based on known data representing collision between subgroups.

6. A computer readable recording medium storing a program for executing a method of operating an RFID (Radio Frequency Identification) system including multiple RFID readers on a computer, comprising:

grouping RFID readers spaced apart by more than a spacing distance to avoid collision between RFID readers into a single group to determine at least one group;

classifying RFID readers included in each group into at least one sub-group based on a read time of each RFID reader; and

driving the RFID readers such that RFID readers belonging to at least two different sub-groups that do not collide with each other simultaneously operate;

wherein driving the RFID readers comprises;

allowing RFID readers belonging to a first group to start to operate;

detecting a first sub-group that finishes the operation thereof among sub-groups included in the first group;

determining a second sub-group which belongs to a second group different from the first group and includes RFID readers that collide with RFID readers belonging to the first sub-group; and

allowing the RFID readers belonging to the second sub-group to operate after the RFID readers belonging to the first sub-group finish the operations thereof.

7. A system of operating an RFID system including multiple RFID readers, comprising:

a grouping unit grouping RFID readers spaced apart by more than a spacing distance to avoid collision between RFID readers into a single group to determine at least one group;

a classification unit classifying RFID readers included in each group into at least one sub-group based on a read time of each RFID reader;

a driving unit driving the RFID readers such that RFID readers belonging to at least two different sub-groups that do not collide with each other simultaneously operate; and

an identification unit detecting a first sub-group that finishes the operation thereof among sub-groups included in a first group and providing the detection result to the driving unit, wherein the driving unit determines a second sub-group which belongs to a second group different from the first group and includes RFID readers that collide with RFID readers belonging to the first sub-group and allows the RFID readers belonging to the second sub-group to operate after the RFID readers belonging to the first sub-group finish the operations thereof.

8. The system according to claim 7, wherein the grouping unit selects an RFID reader spaced apart from a predetermined reference reader by more than the spacing distance and excludes the selected RFID reader from the corresponding group when a distance between the selected RFID reader and an RFID reader included in the group other than the reference RFID reader is shorter than the spacing distance.

9. The system according to claim 7, wherein the grouping unit determines a distance between the RFID readers based on the coordinates of the RFID readers.

10. The system according to claim 7, wherein the spacing distance is determined based on readable distances of the RFID readers.

11. The system according to claim 7, wherein the second sub-group is determined based on known data representing collision between sub-groups.