SYNCHRONIZATION METHOD BETWEEN READER AND TAG

• US 20090153309A1
• Filed: 11/05/2008
• Published: 06/18/2009
• Est. Priority Date: 12/17/2007
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: CHOI, Su Na, KIM, Hyunseok, PYO, Cheol Sig, CHAE, Jong-Suk, LEE, Heyung Sub, SEONG, Nak Seon
• Granted Patent: US 8,274,374 B2
• Time in Patent Office: Days
• US Class Current: 340/10.510
• 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

Abstract

Disclosed is a synchronization method between a reader and tag according to an example embodiment, the method including: transmitting, by the reader, a first write command message to the tag at a first time; detecting, by the tag, the first write command message from the reader at a second time and transmitting a first response message to the reader in response to the first write message; transmitting, by the reader, a second write command message including first time information of the first time to the tag; and correcting, by the tag, a clock offset using a difference between the first time and the second time.

Claims

1. A synchronization method between a reader and a tag, comprising:

transmitting, by the reader, a first write command message to the tag at a first time;

detecting, by the tag, the first write command message from the reader at a second time and transmitting a first response message to the reader in response to the first write message;

transmitting, by the reader, a second write command message including first time information of the first time to the tag; and

correcting, by the tag, a clock offset using a difference between the first time and the second time.

2. The method of claim 1, wherein the reader and the tag respectively include a Real Time Clock (RTC), and the tag corrects a time of the RTC by adding a difference between the first time and the second time to the present time, or subtracting the difference between the first time and the second time from the present time.

3. The method of claim 1, wherein the reader records, in a memory region, the first time information of the first time, fourth time information of a fourth time, the fourth time being a time when the first response message is received from the tag, and fifth time information of a fifth time, the fifth time being a time when the second write command message is transmitted to the tag.

4. The method of claim 1, wherein the tag records the first time information of the first time, second time information of the second time, third time information of a third time, the third time being a time when the first response message is transmitted to the reader, and sixth time information of a sixth time, the sixth time being a time when the second write command message is received from the reader.

5. The method of claim 1, further comprising:

transmitting, by the tag, a second response message in response to the second write command message at a seventh time;

detecting, by the reader, the second response message from the tag at an eighth time and recording eighth time information of the eighth time in a memory region;

transmitting, by the reader, a third write command message including the eighth time information to the tag at a ninth time;

receiving, by the tag, the third write command message from the reader at a tenth time; and

correcting, by the tag, a message delay time using a difference between the seventh time and the eighth time.

6. The method of claim 5, wherein the correcting comprises:

adding a value to the tenth time or subtracting the value from the tenth time, the value being obtained by dividing a difference between the seventh time and the eighth time by 2.

7. A synchronization method between a reader and tag, comprising:

transmitting a second write command message including first time information of a first time to the tag at a fifth time, when the reader receives a first response message from the tag at a fourth time in response to a first write command message transmitted to the tag at the first time;

correcting a clock offset using a difference between a second time and the first time, the second time being a time when the tag receives the first write command message from the reader;

transmitting, by the tag, a second response message to the reader at a seventh time in response to the second write command message;

transmitting a third write command message including eighth time information of an eighth time at a ninth time, when the reader receives the second response message from the tag at the eighth time; and

correcting, by the tag, a delay time using a difference between the seventh time and the eighth time.

8. The method of claim 7, wherein the message delay time is generated between the fourth time and the fifth time and between the eighth time and the ninth time.

9. The method of claim 7, the correcting comprising:

adding a value to the tenth time or subtracting the value from the tenth time, when the tag receives the third write command message from the reader, the value being obtained by dividing a difference between the seventh time and the eighth time by 2.

10. A synchronization method between a reader and a tag, comprising:

transmitting, by the reader, a first read command message including first time information to the tag at a first time;

transmitting a second time message including second time information to the reader at a third time, the second time information being information of a second time, the second time being a time when the tag detects the first read command message from the reader; and

correcting, by the reader, a clock offset using a difference between the first time and the second time.

11. The method of claim 10, wherein the correcting comprises:

adding a difference between the first time and the second time to the present time or subtracting the difference between the first time and the second time from the present time.

12. The method of claim 10, further comprising:

transmitting, by the reader, the second read command message to the tag at a fifth time;

transmitting a second response message including third time information of the third time to the reader at a seventh time in response to the second read command message, when the tag receives the second read command message from the reader at a sixth time; and

correcting, by the reader, a message delay time using a difference between the third time and the fourth time.

13. The method of claim 12, wherein the correcting comprises:

adding a value to the eighth time or subtracting the value from the eighth time, when the reader receives the second response message from the tag, the value being obtained by dividing a difference between the third time and the fourth time by 2.