Method for raising communication reliability of radio frequency identification system

A radio frequency identification system and reliable technology, applied in the field of radio frequency identification, can solve the problems of low information error rate, difficulty in correctly demodulating the returned data of tags, and difficulty in detection of card readers, etc., to achieve reliable communication, improve communication confidentiality performance, and resist Effect of Noise Performance Improvement

Inactive Publication Date: 2007-08-22
TSINGHUA UNIV
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

[0006] For the problems referred to above, the purpose of the present invention is to provide a method for improving the communication reliability of radio frequency identification system, adopt the method of the present invention can make RFID system obtain lower information error rate under the condition of low signal-to-noise ratio, solve the problem of card reader Problems that are difficult to detect or to correctly demodulate the data returned by tags

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  • Method for raising communication reliability of radio frequency identification system
  • Method for raising communication reliability of radio frequency identification system

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Embodiment 1

[0035] Based on the RFID system using the m-sequence as the spreading code, the m-sequence with different digits can be selected according to different performance requirements. The sequence and its initial state must be consistent in the tag and the reader. For example, when a 6-bit m-sequence is selected, the spread spectrum gain is 127 times, that is, the ratio of the output SNR of the system to the input SNR is 127 times. As shown in Figure 3, this embodiment directly performs data modulation on the baseband signal after spectrum spreading, specifically including the following steps:

[0036] 1) The baseband digital signal adopts NRZ encoding, and the data information of the label is sent to the spread spectrum module, and the direct sequence spread spectrum is performed through the 6-bit m sequence, and the spread spectrum gain is 127 times;

[0037]2) The baseband signal after frequency spreading is sent to the reverse modulation module, ASK or PSK modulation can be perf...

Embodiment 2

[0042] The RFID system based on the second embodiment uses the m-sequence as the spreading code, and the m-sequence with different digits can be selected according to different performance requirements, and the sequence and its initial state must be consistent in the tag and the card reader. For example, when using a 6-bit m-sequence, the spread spectrum gain is 127 times, that is, the ratio of the system's output signal-to-noise ratio to the input signal-to-noise ratio is 127 times. As shown in Figure 4, in this embodiment, data modulation is performed after performing subcarrier modulation on the baseband signal after spectrum spreading, so as to further improve the communication reliability of the RFID system, specifically including the following steps:

[0043] 1) The baseband digital signal uses NRZ encoding to send the data information of the tag to the spread spectrum module, and performs direct sequence spread spectrum through the 6-bit m-sequence, and the spread spectr...

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Abstract

This invention relates to a method for increasing communication reliability of RF identifying system including: 1, adding a direct sequence spread spectrum circuit in labels in the reverse link between the communications of a label and a card reader and adding a spread spectrum code and a de-spread circuit same to the direct sequence spread spectrum circuit in the card reader, 2, the baseband data to be sent by the label is engaged in direct sequence spread spectrum by the preset spread code and the spread circuit, 3, modulating the baseband data after being spread onto a carrier, 4, the label feedback signal is reflected to the reader via the antenna, 5, said reader demodulates the carrier reflected by the label, 6, said reader de-spreads the baseband signal by the spreading code in conformity with the label to get the baseband data sent by the label.

Description

technical field [0001] The invention relates to a radio frequency identification method in the communication field, in particular to a method for improving communication reliability of a radio frequency identification system. Background technique [0002] RFID (Radio Frequency Identification) technology in the communication field is an automatic item identification technology that uses radio frequency to conduct long-distance communication to identify items. This technology is mainly adapted to today's digital mobile commerce, and can realize automatic identification and remote real-time monitoring and management. It is one of the popular technologies in contemporary information technology. Install the RFID tag on the object that needs to be authenticated, and the tag sends the identity information about the object to the receiving device through electromagnetic waves. In this way, the RFID system can be used to track and manage almost all physical objects. RFID technology ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06K7/00
Inventor 李敏张春李永明王志华
Owner TSINGHUA UNIV
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