DATA TRANSMISSION METHOD IN PASSIVE COMMUNICATION SYSTEM

• US 20130113611A1
• Filed: 01/24/2011
• Published: 05/09/2013
• Est. Priority Date: 08/27/2010
• Status: Active Grant

• Current Assignee: Korea University Research and Business Foundation
• Original Assignee: Korea University Research and Business Foundation
• Inventors: Kim, Jong-Ok, Kim, Seon Wook, Hwang, Seok Joong
• Granted Patent: US 9,136,977 B2
• Time in Patent Office: Days
• US Class Current: 340/10.34
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer
• CPC Class Codes: H04L 1/0007 by modifying the frame length
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04W 4/12 Messaging; Mailboxes; Announcements

Abstract

This invention relates to a data transmission method in a passive communication system being wirelessly powered up and being passively operable, without using its own power, for data transmission and reception, such as in a passive RFID (Radio Frequency IDentification) communication system, which is capable of effectively configuring a message transmitted by a passive device, thereby providing improved transmission efficiency.

Claims

1. A data transmission method in a passive communication system including a passive device having no own power source and an active device which wirelessly supplies power to the passive device and communicates with the passive device, comprising the steps of:

a) by the active device, transmitting a request message including the number of synchronization signals determined on the basis of communication environmental information; and

b) by the passive device, transmitting a response message to the active device, the response message including a message fragment package including a synchronization signal and one or more message fragment,

wherein the message fragment package is constructed by the number of synchronization signals included in the request message of the active device.

2. The data transmission method according to claim 1, wherein the active device determines the number of message fragments located between the synchronization signals on the basis of the communication environmental information and includes the determined number of message fragments in the request message.

3. The data transmission method according to claim 2, wherein each of the message fragments includes an identification number and a checksum to determine whether or not data are normally received.

4. The data transmission method according to claim 3, further comprising the step of:

c) when an error occurs in data included in the message fragments received by the active device, by the active device, recording the error to correspond to the message fragment using the identification number of each of the message fragments.

5. The data transmission method according to claim 4, further comprising the steps of:

d) by the active device, in the even of the error, transmitting a re-transmission request message including a bit flag corresponding to the identification number of the message fragment to the passive device; and

e) by the passive device, constructing only data for a message fragment corresponding to the bit flag in conformance to a structure of the response message and transmitting the constructed data to the active device.

6. The data transmission method according to claim 4, further comprising the steps of:

f) by the active device, collecting error statistics for message fragments having the same distance from the synchronization signals using the error record;

g) by the active device, obtaining an offset of a bit error probability using the error statistics depending on the size of corresponding ones of the message fragments having the same distance; and

h) obtaining a slope of the bit error probability depending on the number of message fragments between the synchronization signals.

7. The data transmission method according to claim 6, further comprising the step of:

i) by the active device, obtaining a set, {message fragment size, synchronization signal interval, the number of synchronization signals}, to allow the response message structure to be optimal to communication environments using the offset and slope of the bit error probability, and request the passive device to apply this set.

8. The data transmission method according to claim 7, further comprising the step of:

after the step i),

j) by the active device, initializing the error record after the response message structure is changed.

9. The data transmission method according to claim 1, further comprising the step of:

k) by the active device, acquiring synchronization by detecting the synchronization signals from the response message received by the active device, and decoding data of the response message.

10. The data transmission method according to claim 1, wherein the passive device is a passive RFID.