CN102055482B - Data transmission method - Google Patents

Abstract

The present invention provides a data coding method applied to the tag side in a passive radio frequency identification system. The technical solution is to use the same length coding for binary data 0 and binary data 1, and if the binary data 1 uses an intermediate phase jump coding method, then Binary data 0 adopts the encoding method of intermediate phase without jumping; if binary data 0 adopts the encoding method of intermediate phase jumping, then binary data 1 adopts the encoding method of intermediate phase without jumping. The encoding method provided by the present invention can reduce the phase jump probability between the encoding waveforms of two adjacent binary data in the encoding, so as to solve the phase between the encoding waveforms of two adjacent binary data existing in the existing encoding method Problems with high jump probability.

Description

A data encoding method applied to tag end in passive radio frequency identification system

technical field

The invention belongs to the technical field of radio frequency identification communication, and in particular relates to a data encoding method applied in a radio frequency identification system.

Background technique

Radio Frequency Identification (RFID) communication technology is a non-contact automatic identification technology; the radio frequency identification system is mainly composed of tags, readers and computer network systems. The reader communicates with the tag through radio frequency signals, obtains the identification information stored on the tag, and at the same time manages and transmits the read tag information through the computer network system.

RFID systems can be divided into two categories: passive RFID systems and active RFID systems, the main difference between the two is the label side. The tags of the passive RFID system need to obtain energy from the RF signal emitted by the reader, while the tags of the active RFID system can provide energy by themselves.

In the passive RFID system, the reader sends the encoded and modulated RF signal to the tag, and the tag encodes the reply data information and modulates it into a backscattered RF signal, and then sends it to the reader. In radio frequency identification international standards, such as ISO 18000-6A/B/C, the encoding method of the tag before sending the data information to the reader is usually FM0 or Miller encoding. However, there is a phase jump between any two encoded waveforms of binary data in FM0 encoding, and the jump probability is 100%; there is a phase jump between two adjacent binary data 0 encoded waveforms in Miller encoding, and the jump probability is 25%. Frequent phase jumps will lead to spectrum energy leakage and broaden the signal spectrum.

Contents of the invention

The main purpose of the present invention is to provide a data encoding method applied to the tag side in the passive radio frequency identification system, which can reduce the phase jump probability between the encoded waveforms of two adjacent binary data in the encoding, so as to solve the problem of existing encoding The method has the problem that the phase jump probability between two adjacent binary data encoding waveforms is relatively high.

The technical scheme 1 of the present invention is, a kind of data coding method, is applied to the label end of passive radio frequency identification system, is characterized in that, comprises the following steps:

Assume that S ₁ represents the high level with no intermediate phase transition, S ₂ represents the falling edge of the intermediate phase transition, S ₃ represents the rising edge of the intermediate phase transition, and S ₄ represents the low level with no intermediate phase transition.

use the same length encoding for binary data 0 and binary data 1; and

If the first two bits of the binary data sequence to be transmitted are 00, use S ₁ S ₁ encoding, that is, the first bit 0 is encoded by S ₁ , and the second bit 0 is also encoded by S ₁ ;

If the first two bits of the binary data sequence to be transmitted are 01, use S ₁ S ₂ encoding, that is, the first bit 0 is encoded by S ₁ , and the second bit 1 is encoded by S ₂ ;

If the first two bits of the binary data sequence to be transmitted are 10, use S ₂ S ₄ encoding, that is, the first bit 1 is encoded by S ₂ , and the second bit 0 is encoded by S ₄ ;

If the first two bits of the binary data sequence to be transmitted are 11, S ₂ S ₃ encoding is used, that is, the first bit 1 is encoded by S ₂ , and the second bit 1 is encoded by S ₃ ; and

If the K-th bit of binary data to be transmitted is 0 (for the convenience of description, it is assumed that the subsequent binary data to be transmitted is located in the K-th bit of the binary data sequence to be transmitted, and K>2), and

If the K-1 bit binary data is 0, then:

If the K-2 and K-1 binary data are 00 and S ₁ S ₁ is used for encoding, then the K-th binary data 0 is encoded with S ₄ ;

If the K-2 and K-1 binary data are 00 and S ₁ S ₄ encoding is adopted, then the K-th binary data 0 adopts S ₄ encoding;

If the K-2 and K-1 binary data are 00 and encoded with S ₄ S ₁ , then the K-th binary data 0 is encoded with S ₁ ;

If the K-2 and K-1 binary data are 00 and S ₄ S ₄ encoding is adopted, then the K-th binary data 0 adopts S ₁ encoding;

If the K-2th and K-1th binary data are 10 and adopt S ₂ S ₄ encoding, then the K-th binary data 0 adopts S ₄ encoding;

If the K-2th and K-1th binary data are 10 and adopt S ₃ S ₁ encoding, then the K-th binary data 0 adopts S ₁ encoding;

If the K-1 bit binary data is 1, then:

If the K-1th binary data 1 adopts _S2 encoding, then the Kth binary data 0 adopts _S4 encoding;

If the K-1th binary data 1 adopts _S3 encoding, then the Kth binary data 0 adopts _S1 encoding.

If the K-th bit of binary data to be transmitted above is 1, and

If the K-1 bit binary data is 0, then:

If the K-1th binary data 0 adopts _S1 encoding, then the Kth binary data 1 adopts _S2 encoding;

If the K-1th binary data 0 adopts _S4 encoding, then the Kth binary data 1 adopts _S3 encoding;

If the K-1 bit binary data is 1, then:

If the K-1th binary data 1 adopts _S2 encoding, then the Kth binary data 1 adopts _S3 encoding;

If the K-1th binary data 1 adopts _S3 encoding, then the Kth binary data 1 adopts _S2 encoding.

If the positions of the binary data 0 and the binary data 1 in the above embodiment are exchanged, a technical solution 2 of an encoding method is formed.

The beneficial effects of the present invention are: the combination of phase hopping and non-phase hopping encoding methods controls the phase hopping probability between waveforms in binary data sequence coding, so that the phase hopping between encoded binary data waveforms The probability is only 12.5%; compared with FM0 and Miller encoding methods, the probability of phase jump between encoded waveforms of encoded binary data is reduced by 87.5% and 50% respectively; under the premise of the same data rate, the signal spectrum The energy is more concentrated and the spectrum is narrower.

Description of drawings

Fig. 1 is a schematic diagram of binary data encoding baseband symbols provided by a specific embodiment of the present invention;

Fig. 2 is the binary data encoding state transition diagram that technical scheme 1 of the present invention provides;

Fig. 3 is a schematic diagram of baseband symbol sequences after binary data encoding in a specific embodiment of technical solution 1 of the present invention;

Fig. 4 is the schematic diagram of the baseband symbol sequence of FM0 code;

Fig. 5 is the schematic diagram of the baseband symbol sequence of Miller code;

FIG. 6 is a comparison diagram of the frequency spectrum of the binary data encoded baseband signal obtained by the three encoding methods.

Detailed ways

The encoding method of the present invention will be described in detail below with reference to the drawings and embodiments.

Fig. 1 is a schematic diagram of binary data encoding baseband symbols provided by a specific embodiment of the present invention, wherein the abscissa of each figure is the time axis, and the ordinate is the amplitude axis. (a) in the figure indicates the high level S ₁ with no intermediate phase transition, (b) indicates the falling edge S ₂ of the intermediate phase transition, (c) indicates the rising edge S ₃ of the intermediate phase transition, (d) Low level S ₄ indicating that the intermediate phase does not jump. The technical scheme 1 provided by the present invention is to encode the binary data 1 with _S2 or _S3 , and the binary data 0 is encoded with _S1 or _S4 ; the technical scheme 2 is to encode the binary data 0 with _S2 or _S3 , and the binary data 1 coded with S ₁ or S ₄ .

Fig. 2 is the state transfer diagram of binary data encoding provided by technical scheme 1 of the present invention, wherein:

◇If currently in S ₁ state:

1) If the immediately preceding state is in the S ₁ state, when the binary data 0 is received, the state transitions to S ₄ , and there is a phase jump in the state transition; when the binary data 1 is received, the state transitions to S ₂ , and the state transition has no phase Jump.

2) If the immediately preceding state is not in the S ₁ state, when the binary data 0 is received, the state transfers to S ₁ , and the state transfer has no phase jump; when the binary data 1 is received, the state transfers to S ₂ , and the state transfer does not phase jump.

◇If currently in S ₂ state:

When binary data 0 is received, the state transfers to S ₄ , and there is no phase jump in the state transfer;

When binary data 1 is received, the state transfers to S ₃ , and there is no phase jump in the state transfer.

◇If currently in S ₃ state:

When binary data 0 is received, the state transitions to S ₁ , and there is no phase jump in the state transition.

When binary data 1 is received, the state transitions to S ₂ , and there is no phase jump in the state transition.

◇If currently in S ₄ state:

1) If the immediately preceding state is in the S ₄ state, when the binary data 0 is received, the state transitions to S ₁ , and there is a phase jump in the state transition; when the binary data 1 is received, the state transitions to S ₃ , and the state transition has no phase Jump;

2) If the immediately preceding state is not in the S ₄ state, when the binary data 0 is received, the state transfers to S ₄ , and the state transfer has no phase jump; when the binary data 1 is received, the state transfers to S ₃ , and the state transfer does not phase jump;

Among the above 4 states, there may be a phase jump between the binary data encoded waveforms only when the state is currently in the S ₁ and S ₄ states, and the jump probability is 25%. Therefore, the phase jump probability between encoded waveforms of binary data is 12.5% in the whole encoding process.

Fig. 3 is a schematic diagram of the baseband symbol sequence after binary data encoding in a specific implementation of technical solution 1 of the present invention. Data 1, namely (1)00 shown in the figure, is coded by S ₁ S ₁ or S ₄ S ₄ . If the previous bit is binary data 0, that is (0)00 shown in the figure, it is coded by S ₁ S ₄ or S ₄ S ₁ ; binary data sequence 01 is coded by S ₁ S ₂ or S ₄ S ₃ ; binary data The sequence 10 adopts S ₂ S ₄ or S ₃ S ₁ encoding; the binary data sequence 11 adopts S ₂ S ₃ or S ₃ S ₂ encoding. Apparently, the phase jump probability between the encoded waveforms of two binary numbers (time T) is 12.5%.

Figure 4 is a schematic diagram of the baseband symbol sequence of FM0 encoding, wherein: the binary data sequence 00 adopts S ₂ S ₂ or S ₃ S ₃ encoding; the binary data sequence 01 adopts S ₂ S ₁ or S ₃ S ₄ encoding; the binary data sequence 10 adopts S ₁ S ₃ or S ₄ S ₂ encoding; binary data sequence 11 adopts S ₁ S ₄ or S ₄ S ₁ encoding. Obviously, there must be a phase jump between the FM0 encoded waveforms of two binary numbers (time T), and the probability of the jump is 100%.

Figure 5 is a schematic diagram of the baseband symbol sequence of Miller encoding, in which: the binary data sequence 00 is coded by S ₁ S ₄ or S ₄ S ₁ ; the binary data sequence 01 is coded by S ₁ S ₂ or S ₄ S ₃ ; the binary data sequence 10 is coded by S ₂ S ₄ or S ₃ S ₁ encoding; binary data sequence 11 adopts S ₂ S ₃ or S ₃ S ₂ encoding. Obviously, after the Miller encoding of the binary data sequence, only the phase jump occurs between the encoded waveforms of the binary data sequence 00 (time T), and other cases include between the encoded waveforms of the binary data sequences 01, 10, and 11 (time T) There is no phase jump. Therefore, the probability of phase jump between encoded waveforms of binary data (time T) during Miller encoding is 25%.

Fig. 6 is the comparison chart of binary data coded baseband signal spectrum obtained by three kinds of coding methods, including data coded baseband signal spectrum 601 of the present invention, FMO coded baseband signal spectrum 602 and Miller coded baseband signal spectrum 603, wherein the abscissa is digital frequency, The ordinate is the normalized spectral magnitude. Compared with FMO and Miller encoding, when using the encoding method of the present invention, the probability of phase jump of the encoded waveform of binary data is reduced by 87.5% and 50%, respectively, so the signal spectrum is narrower and the energy is more concentrated.

Claims (2)

1. A data encoding method applied to a tag end in a passive radio frequency identification system, characterized in that, comprising the steps of: Assume that S ₁ represents the high level with no intermediate phase transition, S ₂ represents the falling edge of the intermediate phase transition, S ₃ represents the rising edge of the intermediate phase transition, and S ₄ represents the low level with no intermediate phase transition; use the same length encoding for binary data 0 and binary data 1; and If the first two bits of the binary data sequence to be transmitted are 00, use S ₁ S ₁ encoding; If the first two bits of the binary data sequence to be transmitted are 01, use S ₁ S ₂ encoding; If the first two bits of the binary data sequence to be transmitted are 10, use S ₂ S ₄ encoding; If the first two bits of the binary data sequence to be transmitted are 11, use S ₂ S ₃ encoding; and If the Kth binary data to be transmitted is 0, K>2, and If the K-1 bit binary data is 0, then: If the K-2 and K-1 binary data are 00 and S ₁ S ₁ is used for encoding, then the K-th binary data 0 is encoded with S ₄ ; If the K-2 and K-1 binary data are 00 and S ₁ S ₄ encoding is adopted, then the K-th binary data 0 adopts S ₄ encoding; If the K-2 and K-1 binary data are 00 and encoded with S ₄ S ₁ , then the K-th binary data 0 is encoded with S ₁ ; If the K-2 and K-1 binary data are 00 and S ₄ S ₄ encoding is adopted, then the K-th binary data 0 adopts S ₁ encoding; If the K-2th and K-1th binary data are 10 and adopt S ₂ S ₄ encoding, then the K-th binary data 0 adopts S ₄ encoding; If the K-2th and K-1th binary data are 10 and adopt S ₃ S ₁ encoding, then the K-th binary data 0 adopts S ₁ encoding; If the K-1 bit binary data is 1, then: If the K-1th binary data 1 adopts _S2 encoding, then the Kth binary data 0 adopts _S4 encoding; If the K-1th binary data 1 adopts _S3 encoding, then the Kth binary data 0 adopts _S1 encoding; If the K-th bit of binary data to be transmitted is 1, and If the K-1 bit binary data is 0, then: If the K-1th binary data 0 adopts _S1 encoding, then the Kth binary data 1 adopts _S2 encoding; If the K-1th binary data 0 adopts _S4 encoding, then the Kth binary data 1 adopts _S3 encoding; If the K-1 bit binary data is 1, then: If the K-1th binary data 1 adopts _S2 encoding, then the Kth binary data 1 adopts _S3 encoding; If the K-1th binary data 1 adopts _S3 encoding, then the Kth binary data 1 adopts _S2 encoding. 2. A data encoding method applied to a tag end in a passive radio frequency identification system, characterized in that, comprising the following steps: Assume that S ₁ represents the high level with no intermediate phase transition, S ₂ represents the falling edge of the intermediate phase transition, S ₃ represents the rising edge of the intermediate phase transition, and S ₄ represents the low level with no intermediate phase transition; use the same length encoding for binary data 0 and binary data 1; and If the first two bits of the binary data sequence to be transmitted are 11, use S ₁ S ₁ encoding; If the first two bits of the binary data sequence to be transmitted are 10, use S ₁ S ₂ encoding; If the first two bits of the binary data sequence to be transmitted are 01, use S ₂ S ₄ encoding; If the first two bits of the binary data sequence to be transmitted are 00, use S ₂ S ₃ encoding; and If the Kth binary data to be transmitted is 1, K>2, and If the K-1 bit binary data is 1, then: If the K-2 and K-1 binary data are 11 and are encoded by S ₁ S ₁ , then the K-th binary data 1 is encoded by S ₄ ; If the K-2th and K-1th binary data are 11 and S ₁ S ₄ is used for encoding, then the K-th binary data 1 is encoded with S ₄ ; If the K-2 and K-1 binary data are 11 and are encoded by S ₄ S ₁ , then the K-th binary data 1 is encoded by S ₁ ; If the K-2th and K-1th binary data are 11 and adopt S ₄ S ₄ encoding, then the K-th binary data 1 adopts S ₁ encoding; If the K-2 and K-1 binary data are 01 and S ₂ S ₄ encoding is adopted, then the K-th binary data 1 is encoded by S ₄ ; If the K-2 and K-1 binary data are 01 and are encoded by S ₃ S ₁ , then the K-th binary data 1 is encoded by S ₁ ; If the K-1 bit binary data is 0, then: If the K-1th binary data 0 adopts _S2 encoding, then the Kth binary data 1 adopts _S4 encoding; If the K-1th binary data 0 adopts _S3 encoding, then the Kth binary data 1 adopts _S1 encoding; If the K-th bit of binary data to be transmitted is 0, and If the K-1 bit binary data is 1, then: If the K-1th binary data 1 adopts _S1 encoding, then the Kth binary data 0 adopts _S2 encoding; If the K-1th binary data 1 adopts _S4 encoding, then the Kth binary data 0 adopts _S3 encoding; If the K-1 bit binary data is 0, then: If the K-1th binary data 0 adopts _S2 encoding, then the Kth binary data 0 adopts _S3 encoding; If the K-1th binary data 0 adopts _S3 encoding, then the Kth binary data 0 adopts _S2 encoding.

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