Data transmission method in passive communication system
First Claim
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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, the method comprising the steps of:
- a) by the active device, determining a number of synchronization signals and a number of message fragments located between the synchronization signals on the basis of communication environmental information, and transmitting a request message including the number of synchronization signals and the number of message fragments;
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 fragments, wherein the message fragment package is constructed by the number of synchronization signals included in the request message of the active device, and each of the message fragments includes an identification number and a checksum to determine whether data are normally received or not;
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 received message fragments using the identification number of each of the message fragments;
d) by the active device, in the event 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;
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;
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) by the active device, obtaining a slope of the bit error probability depending on the number of message fragments between the synchronization signals.
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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.
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5 Claims
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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, the method comprising the steps of:
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a) by the active device, determining a number of synchronization signals and a number of message fragments located between the synchronization signals on the basis of communication environmental information, and transmitting a request message including the number of synchronization signals and the number of message fragments; 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 fragments, wherein the message fragment package is constructed by the number of synchronization signals included in the request message of the active device, and each of the message fragments includes an identification number and a checksum to determine whether data are normally received or not; 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 received message fragments using the identification number of each of the message fragments; d) by the active device, in the event 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; 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; 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) by the active device, obtaining a slope of the bit error probability depending on the number of message fragments between the synchronization signals. - View Dependent Claims (2, 3, 4, 5)
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Specification