CN102096834A - Data communication method of FM0-code-based label and reader-writer - Google Patents
Data communication method of FM0-code-based label and reader-writer Download PDFInfo
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Abstract
The invention relates to a data communication method of a reverse link between an FM0-code-based label and a reader-writer. The data communication method comprises the following steps that: the label is activated after entering a recognition range of the reader-writer and awaits an order of the reader-writer; the reader-writer sends a search instruction to the label; the label receives the instruction and generates a random number, judges whether the random number is zero, and sends a frame synchronization sequence and an identity recognition code to the reader-writer if the random number is zero, and otherwise, awaits the next search instruction sent by the reader-writer; the reader-writer receives a data signal comprising the frame synchronization sequence and the identity recognition code which are sent by the label, judges whether the data signal is synchronous, if so, sends a base band order to the label, and otherwise, sends the next search instruction.
Description
Technical field
The present invention relates to the REID field, more specifically, relate to a kind of be applied to radio-frequency recognition system based on the label of FM0 coding data communications method to the reverse link of read write line.
Background technology
Radio-frequency (RF) identification (RFID) technology is to carry out telecommunication to realize the automatic identification technology of identify objects purpose by RF-wise.
This REID and current digitizing Mobile business adapt, and can realize automatic identification and remote real-time monitoring and management, and it is one of hot technology in the contemporary infotech.The RFID label is installed on the article that need authentication, and this label sends identity information about these article to receiving trap by electromagnetic wave, can be used for following the trail of and managing nearly all physical object by this working method rfid system.RFID is with a wide range of applications in various fields such as industrial automation, business automation, communications and transportation control and management, anti-counterfeiting technologies.
Rfid system mainly is made up of read write line and RFID tag.Hereinafter, abbreviate RFID tag as label.Read write line sends the radiofrequency signal of certain frequency by emitting antenna, when label enters the perform region of emitting antenna, label receives this radiofrequency signal, therefrom obtain energy and be activated, the information that label is preserved self sends to read write line, after read write line carries out the demodulation sign indicating number to received signal, the data message of label is carried out data communication by interface and back bench control system, simultaneously can carry out the order that this control system is sent, realize different functions.
In RFID label and read write line communication process, be a very important problem synchronously, read write line and labeling requirement act in agreement ground co-ordination, just must guarantee to realize synchronous method.In order to discern the beginning of an order or response, need realize by a frame synchronization code, itself does not comprise the data message of label this frame synchronization code, after having set up synchronously between the transceiver, could begin data information but have only, so be the necessity and the prerequisite of carrying out information transmission synchronously by this frame synchronization code.The quality of net synchronization capability will directly affect the performance of communication, if synchronous error or lose will cause communication performance to descend or communication disruption synchronously.Therefore, realize stable, the communication apace of RFID communication system, the synchronism between needing to guarantee to receive and send, the transmit frame synchronizing sequence is to guarantee label and the synchronous key of read write line.
According to RFID reverse link communication characteristics, promptly passive label mainly is to obtain energy from the radiofrequency signal of read write line emission, simultaneously to read write line emission data message, promptly utilizes backscatter technique to come to transmit target information to read write line.In reverse link communication, mainly determine frame synchronization sequence according to these points: 1, require autocorrelation good, this mainly is in order to reduce the false synchronous probability of communication system; 2, require dc balance, this is for the sensitivity that guarantees to receive, and improves net synchronization capability; 3, require continuous high level less, this is because label reflected radio signal for a long time, and less high level can guarantee the working time of label etc.
In international standard ISO/IEC18000-6C, when reverse link adopted the FM0 coding, the frame synchronization sequence of its suggestion had more excellent autocorrelation performance, and comprises the fault symbol in length is 12 sequence.But passive tag reflects to the radiofrequency signal of read write line very a little less than, the frame sequence length of ISO/IEC18000-6C agreement correspondence is shorter, be unfavorable for realizing correct synchronously.
Summary of the invention
In order to address the above problem, the present invention is directed to the FM0 encoding scheme, the data communications method of a kind of new label based on the FM0 coding to the reverse link of read write line proposed.
This method is as follows:
(1) label receives the radio-frequency carrier that read write line sends and is activated and waits for the order of read write line when entering into the identification range of read write line;
(2) read write line sends query statement to begin to take turns identification to label, and this query statement comprises coded system, data transfer rate, the anticollision parameter information of reverse link;
(3) counter of label produces the scale-of-two random number of a 0-15 position according to the anticollision parameter information in the query statement that receives, if this random number is not 0, then waits for the next instruction of read write line; If this random number is 0, then label with the identity code of oneself encode, framing, modulation and launch to read write line with the form of specular scattering, its frame format comprises following three parts:
A) pilot frequency sequence of forming by a plurality of periodic square waves, the number of this square wave is provided by the parameter in the query statement;
B) frame synchronization sequence of forming by 8 data " 1110V00V ", wherein data 0,1 produce behind the FM0 coding, and " V " represents the fault data, and first fault data " V " are by code element " 10 " expression, and second fault data " V " are represented by code element " 00 ";
C) the identification code data to label carries out the data information sequence that the FM0 coding produces;
(4) read write line receives the data-signal of label, and this data-signal is carried out carrying out after the demodulation following steps:
E) extract clock synchronization information by pilot frequency sequence, the clock frequency of inside is carried out self calibration;
F) utilize the frame synchronization sequence of preserving in advance that all sequences that receives is made the displacement related operation, wherein this frame synchronization sequence of preserving in advance also is made up of 8 data " 1110V00V ", data 0,1 produce behind the FM0 coding, " V " represents the fault data, first fault data " V " are by code element " 10 " expression, and second fault data " V " are by code element " 00 " expression, and correlation and predetermined threshold value that computing is obtained compare, if surpass this threshold value, then representative success synchronously;
G) data information sequence is carried out the FM0 decoding, extract data message;
(5) read write line carries out verification to the data message that extracts, if check results is errorless, read write line sends the data access instruction according to the instruction of background computer data management system, and label sends to read write line with the data message of preserving in the internal storage after receiving this data access instruction; Bump if check results shows, then send the conflict disassembly instruction, counter is that counter was set to maximum 0xFFFF, the query statement of wait next round after 0 label received this conflict disassembly instruction; Counter is not that 0 label subtracts 1 with Counter Value, and the process of repeating step (3), (4) finishes up to epicycle;
(6) read write line sends new query statement, begins new one and takes turns identifying, until successfully discerning all labels.
Further, the number of described square wave is 12.
Further, code element " 1 " is the high level of a unit interval length, and code element " 0 " is the low level of a unit interval length.
Further, described threshold value is between maximum related value and inferior big correlation.
Further, described threshold value is 13.
Use the data communication of realization label of the present invention to read write line, its frame synchronization sequence is longer than the frame synchronization sequence of FM0 in the ISO/IEC 18000-6 agreement, autocorrelation function has sharp-pointed unimodal characteristic, does not need to increase the net synchronization capability that just can improve system oversize lock in time preferably; Simultaneously, this sequence high-low level number is identical, does not exist direct current unbalance, can guarantee the sensitivity that receives.
Description of drawings:
Fig. 1 is to use the communication system synoptic diagram of the label of communication means of the present invention to read write line,
Fig. 2 is to use the read write line of data communications method of the present invention and the structured flowchart of label,
Fig. 3 is the timing chart that schematically shows the FM0 coding principle,
Fig. 4 is the synoptic diagram that frame synchronization sequence of the present invention is shown,
Fig. 5 is the curve map that schematically shows the autocorrelation performance of frame synchronization sequence of the present invention,
Fig. 6 is the curve map that the accurate synchronization probability that uses data communications method of the present invention is shown,
Fig. 7 is the curve map that the false synchronous probability of using data communications method of the present invention is shown,
Fig. 8 is the communication flow diagram of label of the present invention to read write line.
Embodiment:
Below in conjunction with accompanying drawing the specific embodiment of the present invention is elaborated.
Fig. 1 is to use the communication system synoptic diagram of the label of communication means of the present invention to read write line, read write line is outwards launched the ACK modulation signal, when one or more labels enter in the working range of read write line, can receive the signal of read write line emission, can return the data message of needs according to the order that receives; Read write line is transferred to computer data management system with it after receiving this data message.
Fig. 2 is to use the read write line of data communications method of the present invention and the structured flowchart of label, as shown in the figure, read write line comprises the radio-frequency front-end with reception and emission function, the modulation-demodulation circuit that is used for modulation and demodulation, the codec that is used for Code And Decode, the synchronization module that is used to produce frame synchronization sequence and carries out synchronous detection, and be used for handling, produce the base band control circuit of base band order and other order or instruction to receiving data; Equally, label also has radio-frequency front-end, modulator-demodular unit, codec, the synchronization module of carrying out identical function, this label also comprises the voltage doubling rectifing circuit that is used for radio-frequency carrier is changed into the needed voltage of label work in addition, be used to preserve the storer of various data messages and be used to carry out data read-write operation and the microprocessor of the various response commands of generation.
Describe the data communications method of label provided by the invention in detail below in conjunction with hardware to read write line, this method is as follows: (1) label receives the high level radio-frequency carrier that read write line sends when entering into the identification range of read write line, its inner voltage doubling rectifing circuit changes into the needed voltage of label work with this carrier wave, and label was activated and waited for the order of read write line this moment; (2) read write line sends a query statement to label, and identification is taken turns in beginning one, and this instruction is produced by the base band control circuit, and it has comprised coded system, data transfer rate, the anticollision parameter information of reverse link; (3) label receives this query statement, anticollision parameter information according to query statement, the microprocessor of label utilizes a counter of its inside to produce the scale-of-two random number of a 0-15 position, if this random number is not 0, then waits for the next instruction of read write line; If this random number is 0, then the label reading and saving in storer identity code and to its encode, framing, modulation and launch to read write line with the form of specular scattering, its frame format comprises following three parts: a) pilot frequency sequence of being made up of a plurality of periodic square waves, the number of this square wave is provided by the parameter in the query statement, can be 12; B) frame synchronization sequence of forming by 8 data " 1110V00V ", wherein data 0,1 produce behind the FM0 coding, and " V " represents the fault data, and first fault data " V " are by code element " 10 " expression, and second fault data " V " are represented by code element " 00 "; C) the identification code data to label carries out the data information sequence that the FM0 coding produces; (4) read write line receives the data-signal of label, and modulator-demodular unit carries out demodulation to this data-signal, and synchronization module is carried out following steps afterwards: e) extract clock synchronization information by pilot frequency sequence, the clock frequency of inside is carried out self calibration; F) utilize the frame synchronization sequence of in synchronization module, preserving in advance that all sequences that receives is made the displacement related operation, wherein this frame synchronization sequence of preserving in advance also is made up of 8 data " 1110V00V ", data 0,1 produce behind the FM0 coding, " V " represents the fault data, first fault data " V " are represented by code element " 10 ", second fault data " V " are represented by code element " 00 ", correlation that computing is obtained and threshold ratio are, if surpass this threshold value, then representative success synchronously, otherwise the query statement of wait next round; After success synchronously, codec carries out the FM0 decoding to data information sequence, extracts data message and sends the base band control circuit to; (5) the base band control circuit of read write line carries out verification to the data message that receives, if check results is errorless, read write line is according to the instruction of background computer data management system, the instruction of transmission data access, label send to read write line with the data message of preserving in the internal storage after receiving this data access instruction; Bump if check results shows, then send the conflict disassembly instruction, counter is that counter was set to maximum 0xFFFF, the query statement of wait next round after 0 label received this conflict disassembly instruction; Counter is not after 0 label is received this conflict disassembly instruction Counter Value to be subtracted 1, and the process of repeating step (3), (4) finishes up to epicycle; (6) read write line sends new query statement, begins new one and takes turns identifying, until successfully discerning all labels.
Fig. 3 is the timing chart that schematically shows the FM0 coding principle.As shown in the figure, according to the FM0 coding rule, binary data 0 is that the low level that the high level with a unit interval length connects a unit interval length is represented, i.e. code element " 10 "; Or the high level that the low level of a unit interval length connects a unit interval length represents, i.e. code element " 01 ".Binary data 1 is to represent with the low level of the high level of two continuous unit interval length or two continuous unit interval length, i.e. code element " 11 " or " 00 ".All to carry out anti-phase between any two adjacent data.
Fig. 4 is the synoptic diagram that frame synchronization sequence of the present invention is shown.There is shown frame synchronization sequence of the present invention is made up of data 0, data 1 and fault data, its form is " 1110V00V ", totally 8 bit data, wherein data 0, data 1 produce according to the FM0 coding principle, " V " expression fault data, first fault data are by code element " 10 " expression, and second fault data represented by code element " 00 ".According to the FM0 coding rule, need to carry out anti-phase between two adjacent data, but in frame synchronization sequence according to the present invention: first fault data " V " have continued the high level of its previous data 0, and second fault data " V " have continued the low level of its previous data 0; Even therefore be interfered, promptly under the condition of lower signal to noise ratio (S/N ratio), the probability that the level of this former and later two code elements of appearance is identical in the process FM0 coded data information sequence is also smaller, thereby can reduce the false synchronous probability of communication system greatly.
Fig. 5 is the curve map that schematically shows the autocorrelation performance of frame synchronization sequence of the present invention, and frame synchronization sequence provided by the invention is by a
n(n=1,2 ..., N, the frame synchronization sequence length of N after for coding is 16 in the present invention) expression, the transverse axis among the figure is that (negative number representation is to moving to left for side-play amount i when carrying out auto-correlation, positive number is represented to move right), the longitudinal axis is a correlation, can be by behind the following formula:
Wherein, N is 16 for the frame synchronization sequence length after encoding in the present invention.Autocorrelation performance is defined as the ratio (representing with decibel) of maximum related value and inferior big correlation.The maximum related value of frame synchronization sequence provided by the invention is 16, inferior big correlation is 3, its autocorrelation performance is 7.27dB, obviously is better than the 4.77dB of the FM0 frame synchronization code among the ISO/IEC 18000-6A/B, and suitable with the 7.78dB of the FM0 frame synchronization code among the ISO/IEC18000-6C.Frame synchronization sequence provided by the invention has sharp-pointed unimodal characteristic, utilizing the displacement related operation to carry out in the synchronization detection process, as long as does not mate fully the position of frame synchronization sequence, the probability that its correlation surpasses a pre-set threshold is just very little, thereby has further reduced the false synchronous probability of system.Under perfect condition, this threshold value equals maximum related value.But in actual applications, consider the influence of interference, if set the threshold to maximum related value, then can cause the accurate synchronization probability on the low side, therefore between the accurate synchronization probability of communication system and false synchronous probability, carry out compromise selection according to user's request, selecting a number between inferior big correlation and maximum related value as decision threshold, is 13 such as this threshold value, realizes the optimization of communication performance thus.
Fig. 6 is the curve map that the accurate synchronization probability that uses data communications method of the present invention is shown, and Fig. 7 is the curve map that the false synchronous probability of using data communications method of the present invention is shown.These two curve maps are the simulation results under white Gaussian noise channel model condition.In simulation process, each Frame is made up of the frame synchronization sequence and the information bit of corresponding definition, and wherein information bit is made up of after corresponding encoded 64 0,1 sequences that produce at random, averages behind the replicate analysis 1000000.During synchronous detection, frame synchronization sequence being made related operation, then is success synchronously greater than predetermined threshold value, otherwise missed synchronization takes place.Further, mobile synchronizing sequence carries out related operation to other locational sequence, if greater than predetermined threshold value, then takes place synchronously false.Decision threshold is relevant with frame synchronization sequence length with coded system.By Fig. 6-7 as can be known, utilize frame synchronization sequence provided by the invention to communicate, have the highest accurate synchronization probability (all higher than 6B-C), its false synchronous probability is lower than the frame synchronization sequence that ISO 18000-6C adopts simultaneously.
Fig. 8 is the communication flow diagram of label of the present invention to read write line, as shown in the figure: label enters the order that is activated in the identification range of read write line and waits for read write line, read write line sends query statement to label, this label receives this instruction back and produces random number, judge whether this random number is 0, if be 0, label is to read write line transmit frame synchronizing sequence and identity code (structure of this frame synchronization sequence describes in detail in the above, repeats no more here); Otherwise label is waited for the next round query statement that read write line sends; Read write line receives the data-signal that comprises frame synchronization sequence and identity code of label transmission and judges whether synchronously, if then send the base band order to label, otherwise sends the next round query statement.
Data communications method provided by the invention has the good autocorrelation energy, greatly reduces false synchronous probability, and the unbalance problem of no direct current can guarantee the sensitivity that receives, and high level is less continuously, guarantees that the farm labourer of label does the time etc.
Claims (5)
1. one kind based on the label of the FM0 coding data communications method to the reverse link of read write line, and it comprises:
(1) label receives the radio-frequency carrier that read write line sends and is activated and waits for the order of read write line when entering into the identification range of read write line;
(2) read write line sends query statement to begin to take turns identification to label, and this query statement comprises coded system, data transfer rate, the anticollision parameter information of reverse link;
(3) counter of label produces the scale-of-two random number of a 0-15 position according to the anticollision parameter information in the query statement that receives, if this random number is not 0, then waits for the next instruction of read write line; If this random number is 0, then label with the identity code of oneself encode, framing, modulation and launch to read write line with the form of specular scattering, its frame format comprises following three parts:
A) pilot frequency sequence of forming by a plurality of periodic square waves, the number of this square wave is provided by the parameter in the query statement;
B) frame synchronization sequence of forming by 8 data " 1110V00V ", wherein data 0,1 produce behind the FM0 coding, and " V " represents the fault data, and first fault data " V " are by code element " 10 " expression, and second fault data " V " are represented by code element " 00 ";
C) the identification code data to label carries out the data information sequence that the FM0 coding produces;
04) read write line receives the data-signal of label, and this data-signal is carried out carrying out after the demodulation following steps:
E) extract clock synchronization information by pilot frequency sequence, the clock frequency of inside is carried out self calibration;
F) utilize the frame synchronization sequence of preserving in advance that all sequences that receives is made the displacement related operation, wherein this frame synchronization sequence of preserving in advance also is made up of 8 data " 1110V00V ", data 0,1 produce behind the FM0 coding, " V " represents the fault data, first fault data " V " are by code element " 10 " expression, and second fault data " V " are by code element " 00 " expression, and correlation and predetermined threshold value that computing is obtained compare, if surpass this threshold value, then representative success synchronously;
G) data information sequence is carried out the FM0 decoding, extract data message;
(5) read write line carries out verification to the data message that extracts, if check results is errorless, read write line sends the data access instruction according to the instruction of background computer data management system, and label sends to read write line with the data message of preserving in the internal storage after receiving this data access instruction; Bump if check results shows, then send the conflict disassembly instruction, counter is that counter was set to maximum 0xFFFF, the query statement of wait next round after 0 label received this conflict disassembly instruction; Counter is not that 0 label subtracts 1 with Counter Value, and the process of repeating step (3), (4) finishes up to epicycle;
(6) read write line sends new query statement, begins new one and takes turns identifying, until successfully discerning all labels.
2. according to the process of claim 1 wherein that the number of described square wave is 12.
3. according to the process of claim 1 wherein that code element " 1 " is the high level of a unit interval length, and code element " 0 " is the low level of a unit interval length.
4. according to the process of claim 1 wherein that described threshold value is between maximum related value and inferior big correlation.
5. according to the method for claim 4, wherein said threshold value is 13.
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| CN105550720A (en) * | 2015-11-27 | 2016-05-04 | 杨刚 | RFID system capable of enhancing read-write distance and read-write method thereof and energy distribution optimization method |
| CN106330266A (en) * | 2016-08-16 | 2017-01-11 | 武汉万集信息技术有限公司 | Method for optimizing communication time sequence of reader/writer and label |
| CN108370309A (en) * | 2015-12-18 | 2018-08-03 | 北欧半导体公司 | Radio communication |
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| CN105550720A (en) * | 2015-11-27 | 2016-05-04 | 杨刚 | RFID system capable of enhancing read-write distance and read-write method thereof and energy distribution optimization method |
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| CN108370309B (en) * | 2015-12-18 | 2021-07-23 | 北欧半导体公司 | Digital radio receiver with frame synchronization for decoding message data |
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| CN106330266B (en) * | 2016-08-16 | 2018-10-16 | 武汉万集信息技术有限公司 | A kind of timing optimization method of reader equipment and reader and label communication |
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Application publication date: 20110615 |