CN101281587B - RFID reading method and answering method - Google Patents

Abstract

The invention relates to a radio frequency identification reading method and a response method, and is especially suitable for improving the anti-collision performance of the radio frequency identification technology. The reading method includes: sending a query command including an orthogonal cyclic code; generating a group of orthogonal despreading codes to despread the received response signal to obtain a response identifier; sending a confirmation command; sending a re-query or query adjustment command and continuing to receive answer signal. The response method includes: receiving a query command containing an orthogonal cyclic code; generating an orthogonal spread spectrum code according to the orthogonal cyclic code, performing spread spectrum modulation on the response identifier to generate a response signal; sending a response signal; waiting for the confirmation command to enter the confirmation state Or receive a query adjustment command to perform subsequent identification steps. The invention adopts the method of combining code division and time division, can identify a plurality of response signals in the same time slot, can effectively prevent collision interference, reduce the time consumption of identification response, and realize safe, reliable and efficient radio frequency identification.

Description

RFID reading method and answering method

technical field

The invention relates to a radio frequency identification reading method and a response method, and is especially suitable for a radio frequency identification reading method and a response method capable of improving the anti-collision performance of the radio frequency identification technology.

Background technique

Radio Frequency Identification (Radio Frequency Identification, hereinafter referred to as RFID) technology is a technology that uses radio backscatter transmission to realize non-contact automatic identification (Auto-ID) of objects. In recent years, it has been widely used in many business fields, such as production process management, supply chain management, logistics and transportation, distribution, retail, transportation control and other systems. Under this development trend, the goal of RFID technology is to expand the amount of data provided by transponders and provide information on individuals, animals, objects and goods extensively.

An RFID system usually consists of two basic devices, a transponder and a reader. The transponder is the data carrier in the RFID system. The reader sends a radio frequency signal of a certain frequency through the transmitting antenna. When the transponder enters the working area of the transmitting antenna, it obtains energy and activates, and sends information such as its own code through the backscattered radio signal to the reader. Reader, after the reader demodulates and decodes the received signal, it exchanges the transponder code and other data with the control computer through the interface, and at the same time executes the command sent from the application system software to realize the corresponding application function.

When the reader performs radio frequency identification on the transponder, when there are many transponders in the antenna radiation field of the reader, the transponders will collide, that is, when multiple transponders send signals at the same time, they will compete for the channel. Signals interfere with each other. The specific manifestation of this situation in the warehouse import and export statistics system is: multiple marked commodities are queried by the same reader at the same time. Solving this type of collision problem involves anti-collision technology, and the design of anti-collision technology will largely affect the performance of the radio frequency identification system. The methods to solve the anti-collision problem in the prior art usually adopt tree search and collision random backoff technology to realize. When the number of transponders to be read is large, the response time of these technologies is relatively long and the real-time performance is poor. For the case where the number of items is large and the reading time is limited, the RFID anti-collision method simply using tree search or collision random backoff technology cannot meet the requirements. On the other hand, with the continuous deepening of RFID applications, more and more information will be carried in the transponder, the data communication volume between the reader and the transponder will also increase, and the information security requirements will become higher and higher. . Therefore, there is a need for an RFID anti-collision technology with high efficiency, fast identification and good information security.

Contents of the invention

The purpose of the present invention is to overcome the defects in the prior art and provide a radio frequency identification reading method and identification method, which can effectively avoid collision interference during the radio frequency identification process and realize rapid identification with high efficiency.

In order to achieve the above purpose, a radio frequency identification reading method is provided, including the following steps:

Step 1. The reader sets the orthogonal cyclic code with code length M as the current orthogonal cyclic code in the parameter of the query command, and determines the shift value N according to the code length M, and the shift value N is less than the code length M is a non-negative integer, and the shift value N is set in the parameter of the query command, and the query command is sent; wherein, M is a positive integer;

Step 2, the reader generates an orthogonal despreading code according to the current orthogonal cyclic code and the shift value N;

Step 3. The reader uses the orthogonal despreading code to despread the received one or more response signals to obtain a response identifier;

Step 4, the reader sends a confirmation command including the response identifier;

Step 5. The reader judges whether the current frame is over, and if so, executes Step 6;

Step 6. The reader re-determines the current orthogonal cyclic code and/or re-determines the shift value N, and sets it in the parameter of the query adjustment command, sends the query adjustment command, and executes step 12.

By performing the above steps, the reader sends the orthogonal cyclic code and the frame length parameter of the current frame to the transponder, and can receive multiple response signals in the same time slot, and at the same time identify multiple transponders that have not collided, and confirm After identifying the identified transponders, use the query adjustment command to start the identification of the next frame, and then identify the transponders that were not identified due to the collision of the response signals in the previous frame, which effectively solves the problem of signal collisions.

This realizes above-mentioned object, also provides a kind of radio frequency identification answering method, comprises the following steps:

Step 1', the responder receives a query command containing an orthogonal cyclic code with a code length of M; wherein, M is a positive integer, and judges whether the query command contains a shift value N, if not, then determines the shift value according to the code length M The bit value N is equal to M-1, where N is a non-negative integer;

Step 2', the transponder generates an orthogonal spread spectrum code according to the orthogonal cyclic code, and uses the orthogonal spread spectrum code to perform spread spectrum modulation on the response identifier to generate a response signal;

Step 3', the transponder sends the response signal;

Step 4', the responder judges whether the confirmation command is received, if so, enters the confirmation state, otherwise executes step 5';

Step 5', the transponder judges whether the query adjustment command is received, and if so, performs identification of the next frame.

By performing the above steps, the transponder cyclically shifts the orthogonal cyclic code sent by the reader to generate a spreading code, and spreads its own response identifier. If no confirmation command is received after sending, it will enter the waiting arbitration state and wait for the start For the query command of the next time slot, if the transponder has sent a response signal but has not received the confirmation command, it may be due to a collision and has not been recognized by the reader, then the transponder waits for the query adjustment command to start the identification of the next frame .

It can be seen from the above technical solutions that the present invention adopts the technical means of combining code division and time division to realize the anti-collision method of RFID system with high efficiency and rapid identification. The hardware complexity and cost overhead of this method are within the allowable range, but the anti-collision performance is greatly improved. The advantages of confidentiality and anti-multipath interference ability overcome the technical problem of long response time of the anti-collision method of radio frequency identification technology.

Therefore, the present invention has the following advantages:

1. The parallel identification of multiple RFID transponders is realized, which reduces the identification time compared with the simple anti-collision method based on the "time slot ALOHA" frame, and can realize the rapid identification of a large number of RFID transponders.

2. Using code division multiplexing in the same time slot, multiple response signals can be identified at the same time, and it has the advantages of strong anti-interference, high signal-to-noise ratio, good confidentiality, and strong anti-multipath interference ability.

3. Due to the use of the self-circulating orthogonal principle of the orthogonal cyclic code to generate the spread spectrum sequence, the manufacturing cost of the transponder and the reading device is within the allowable range, and it is easy to implement using mainstream chip technology at home and abroad.

The present invention will be described in further detail below through specific embodiments and in conjunction with the accompanying drawings.

Description of drawings

FIG. 1A is a schematic structural diagram of a reader implementing Embodiment 1 of the radio frequency identification reading method of the present invention.

FIG. 1B is a schematic structural diagram of a transponder implementing Embodiment 1 of the radio frequency identification response method of the present invention.

FIG. 2 is a flow chart of Embodiment 1 of the radio frequency identification reading method of the present invention.

FIG. 3 is a partial flow chart of Embodiment 2 of the radio frequency identification reading method of the present invention.

FIG. 4 is a flow chart of Embodiment 1 of the radio frequency identification response method of the present invention.

Detailed ways

The basic idea of the present invention is: all transponders receive the orthogonal cyclic code with a certain length and the frame length parameter of the current frame sent by the reader, and each transponder obtains its own orthogonal cyclic code by random phase shifting according to the orthogonal cyclic code. spread spectrum code, and randomly generate its own frame time slot parameters according to the frame length parameters of the current frame. The length of the orthogonal cyclic code is controlled by the reader according to the estimation of the number of transponders in the radio frequency field, so as to ensure the collision recognition of each frame and reduce the time consumption of recognition response. When the transponder performs reflection modulation on the UHF signal of the reader to transmit data by means of two-phase keying or amplitude keying, the data to be sent by the transponder is modulated by the respective generated orthogonal spread spectrum code sequences send. When reading and identifying, the reader locally generates all phase-shifted orthogonal cyclic code sequences, and after receiving the response signal sent by the transponder, uses the excellent autocorrelation and cross-correlation performance of the orthogonal cyclic code sequences to perform despreading processing , and perform radio frequency identification on the transponder according to the result of the despreading process. Both the radio frequency identification reading method and the response method of the present invention are realized based on the radio frequency identification system that adopts "time slot ALOHA" frame access. The "time slot ALOHA" protocol stipulates that channels are divided by time slots, and each time slot just transmits Packet, after the data packet arrives, it must wait until the next time slot to start transmitting. Once a collision occurs between the packets, it will be 100% overlapped. Before sending the response signal, the responder will first randomly generate a frame according to the frame length parameter of the current frame. Slot parameter, when the frame time slot parameter is equal to zero, send a response signal, if the frame time slot parameter is not equal to zero, wait for the re-query command sent by the reader, after receiving the re-query command, reduce the frame time slot parameter by 1 until the frame time slot parameter The response signal is sent when the time slot parameter is zero, that is, the responder will send a response signal in a certain time slot of the current frame. The parameters of the above query command and query adjustment command usually include a frame length parameter, that is, a frame length parameter of the frame to start query, which can be a fixed value or can be reset according to specific conditions. The radio frequency identification reading method and answering method of the present invention will be described in detail below through specific embodiments.

As shown in Figure 2, it is a flowchart of a specific embodiment 1 of the radio frequency identification reading method of the present invention. The structural diagram of the reader in the first embodiment is shown in Figure 1A. The radio frequency identification reading method of the first embodiment specifically includes the following steps:

Step 110, the orthogonal cyclic code that code length is M is set in the parameter of inquiry (hereinafter referred to as Query) order as current orthogonal cyclic code, determines shift value N according to code length M, and this shift value N is less than code A non-negative integer of length M, that is, 0≤N<M, and then send the Query command; where M is an integer;

Step 120, generating an orthogonal despreading code according to the current orthogonal cyclic code and the shift value N;

Step 130, using an orthogonal despreading code to despread one or more received response signals to obtain a response identifier;

Step 140, sending an acknowledgment (hereinafter referred to as Ack) command that includes the response identifier;

Step 150, judging whether the current frame ends, if so, then execute step 160;

Step 160 , sending a query adjustment (hereinafter referred to as AdjustQuery) command to perform identification of the next frame.

The radio frequency identification reading method adopted by the reader in Embodiment 1, that is, the working state mechanism of the reader, is a cyclic process.

In the above step 110, the parameters of the Query command include the frame length parameter of the current frame and an orthogonal cyclic code with a code length of M. The orthogonal cyclic code may be a pre-set orthogonal cyclic code, which is suitable for a situation where the number of transponders simultaneously existing in the radio frequency field is small. Another preferred embodiment is to pre-set a group of orthogonal cyclic codes and store them in the reader as an orthogonal cyclic code set. Before the above step 110, the reader also includes selecting A step of an orthogonal cyclic code, this embodiment is suitable for a situation where the number of transponders in the radio frequency field is relatively large and the orthogonal cyclic code needs to be replaced. The code length of the above-mentioned orthogonal cyclic code is M, and the value range of M can be 8 to 128, and the orthogonal cyclic code of different code length can be selected, so the orthogonal cyclic code set of the reader should contain multiple groups of different digits Orthogonal cyclic codes. When performing the first radio frequency identification and the number of transponders in the radio frequency field cannot be estimated, an initial value can be set first. For example, in this embodiment, the M value is set to 32, and the reader uses the M-bit orthogonal cyclic code Included in the parameters of the reader's Query command to start a round of RFID. The frame length parameter of the current frame included in the Query command is represented by L, and the value range of L is the K power of 2, and the value range of K is usually 4 to 9. In this embodiment, the frame length initial value of the current frame is set to Set to 64. The shift value N determined in step 110 is a non-negative integer smaller than the code length M, and the initial value is set to M-1 by default.

In the above step 120, the step of generating the orthogonal despreading code according to the orthogonal cyclic code and the shift value N is specifically: performing N+1 cyclic shifts on the M-bit orthogonal cyclic code to generate N+1 orthogonal Despreading code.

In the above step 130, if the reader does not receive a new response signal, it means that there is no unidentified transponder within the radio frequency identification range, then the reading process ends, and it waits to enter the next radio frequency identification reading process. If there is an acknowledgment signal that has been received and identified, necessary processing, such as the step of carrier demodulation, is performed first, which is common knowledge of those skilled in the art and will not be repeated here. The unidentified response signal can be received before or after the generation of the orthogonal spreading code, and then the response signal is despread. The specific implementation of the despread process is: using N+1 orthogonal solutions The spreading code despreads the response signal to obtain a despreading result; data decoding is performed on the despreading result to obtain a response identifier.

At this time, if there is no collision, that is, no two or more transponders generate the same orthogonal cyclic spreading code, and send a response signal modulated with the same spreading code in the same time slot, The reader can identify the response identification data of all transponders. If a collision occurs, two or more transponders generate the same orthogonal cyclic spreading code and transmit the spreading code in the same time slot. If the frequency modulated response signal is used, the reader can still identify the identification data of all other transponders that have not collided due to the good autocorrelation and cross-correlation of the orthogonal cyclic code. The above-mentioned step of decoding the data of the despreading result is a demodulation step performed on other data modulations performed on the response identifier, such as Miller (hereinafter referred to as miller) data demodulation. The obtained response identifier is the ID data of the responder.

In step 140, the reader sends an Ack command to all identified transponders one by one, and the Ack command includes response identification data of the responding transponders.

In the above embodiment, after the transponder is identified and confirmed, the reader may further perform step 1450, that is, acquire the application data spread-modulated by the corresponding orthogonal spreading code of the response signal. The above step 1450 can be realized through the following steps:

Step 1450a, the reader sends a read (hereinafter referred to as Read) command that does not contain a response identifier;

In step 1450b, the reader acquires the application data spread-modulated by the corresponding orthogonal spread-spectrum code of the response signal.

The Read command parameter sent by the reader may not contain the response identification data of the specified transponder, which is used to read the application data of all transponders in the confirmed state. This situation is called parallel reading, and the Read command parameter can also contain Specify the response identification data of the transponder. At this time, it is used to read the application data of the transponder that is in the confirmation state and matches the response identification data in the Read command parameter. The reader can read different response identification data one by one by changing the response identification data in the parameter. Transponder data, this case is called serial read. After the transponder receives the read command, it uses the spread spectrum code used when sending the response identifier to perform spread spectrum modulation on the application data and then sends it to the reader. Then the reader can use the generated despreading code to despread the application data, and perform subsequent processing, or send it to a corresponding computer or control device.

After completing the identification and confirmation of a time slot, in step 150, the reader judges whether the current frame ends, if not, then sends a re-inquiry (hereinafter referred to as ReQuery) command, and executes step 130, the unrecognized transponder is in the following Continue to identify in one time slot; if the current frame has ended, but there are still transponders that have not been identified because of the collision of the response signal, the reader then sends an AdjustQuery command that includes the frame length parameter of the next frame, and executes step 160, Enter the identification of the next frame, that is, the transponder generates the frame time slot parameter according to the frame length parameter of the next frame. The frame length parameter can be unchanged, or it can be an updated frame length parameter, and then repeat the data transmission in one frame. Continuing to execute step 130, the reader may receive the response signal sent again by the transponder that collided in the previous frame, until all transponders are identified.

The first embodiment of the above-mentioned radio frequency identification reading method is a reading method based on the combination of time division and code division technology. By using an orthogonal cyclic code with good autocorrelation performance and cross-correlation performance as the prototype code of spread spectrum modulation, a time slot can be realized. The parallel identification of multiple RFID transponders reduces the identification time compared to the simple anti-collision method based on the "time slot ALOHA" frame, and can realize the rapid identification of a large number of RFID transponders, using code division multiplexing in the same time slot The method has the advantages of strong anti-interference, high signal-to-noise ratio, good confidentiality, and strong anti-multipath interference ability. Due to the use of the self-circulating orthogonal principle of the orthogonal cyclic code to generate the spread spectrum sequence, the manufacturing of the reading device The cost is within the allowable range, and it is easy to realize by adopting mainstream chip technology at home and abroad.

As shown in Figure 3, it is a partial flow chart of the second embodiment of the radio frequency identification reading method of the present invention, which specifically includes the following steps:

Step 101, the orthogonal cyclic code that code length is M and the frame length parameter of current frame are set in the parameter of Query command, determine displacement value N according to code length M, and this displacement value N is less than code length M arbitrary Non-negative integer, set the shift value N in the parameter of the Query command, and then send the Query command;

Step 102, generating an orthogonal despreading code according to the orthogonal cyclic code and the shift value N;

Step 103, using an orthogonal despreading code to despread one or more received response signals to obtain a response identifier;

Step 104, sending an Ack command including the response identifier;

Step 105, judging whether the current frame ends, if so, then execute step 106;

Step 106, select a new orthogonal cyclic code from the set of orthogonal cyclic codes, and re-determine the shift value N, update the current orthogonal cyclic code and the shift value, and set it in the parameters of the AdjustQuery command, and then Send the AdjustQuery command including the new orthogonal cyclic code and the shift value N, and execute step 102 .

In the above embodiment, the number of unidentified transponders can be calculated at first, and then the shift value N to be updated and the code length M of the orthogonal cyclic code can be re-determined according to the calculation result, and the frame length parameter in the Query command and the AdjustQuery command parameter is also It can be determined according to the calculation result. To calculate the number of unidentified transponders, the collision rate of the response signals can be estimated according to the number of response signals received in the current frame and the number of identifiable response identifiers, and then the number of unidentified transponders can be estimated. For example, when the number of received response signals is large but the number of identifiable response identifiers is small, it can be estimated that the collision rate is relatively high, that is, there are many unrecognized transponders. Or estimate whether there are unidentified transponders according to the empty slot ratio of the current frame. If the number of unrecognized transponders is large, the frame length of the next frame can be increased accordingly, the code length M of the orthogonal cyclic code can be increased, and the shift value N can also be increased. If the number of unidentified transponders is already small, you can Reducing the frame length of the next frame can reduce the code length M of the orthogonal cyclic code, and can also reduce the shift value N, thereby reducing the response time for performing a frame recognition. The frame length parameter, the code length M of the orthogonal cyclic code, and the shift value N can be adjusted at the same time, or can be adjusted in any combination, and determined according to specific conditions.

In this embodiment, sending the AdjustQuery command by the reader is equivalent to starting the identification of the next frame, so a new orthogonal cyclic code can be selected to update the orthogonal cyclic code used in the previous frame. Selecting a new orthogonal cyclic code may further set the length of the new orthogonal cyclic code according to the estimation result of the number of unidentified transponders. The reader can store orthogonal cyclic code sets of various lengths in advance according to the number of code length digits. If there are a large number of unidentified transponders, the orthogonal cyclic code with a larger length can be selected to generate more orthogonal codes. Spreading codes are used by transponders. If the number of unidentified transponders is small, you can choose an orthogonal cyclic code with a smaller length, so that the reader does not need to generate too many orthogonal spreading codes when despreading. It is also unnecessary to perform excessive despreading processing, and the despreading response time can be reduced. By controlling the number of orthogonal cyclic codes, the response time of recognition can also be reduced.

Embodiment 2 of the reading method of the present invention, the reader uses the above-mentioned AdjustQuery command to instantly adjust the code length of the orthogonal cyclic code, the frame length parameter and the shift of the "time slot ALOHA" frame according to the number of unidentified transponders in the radio frequency field Value N, so as to change the data transmission rate and the number of working time slots per frame according to the situation, and finally adjust the total recognition time, suitable for different specific applications.

As shown in Figure 4, it is a flowchart of a specific embodiment of the radio frequency identification response method of the present invention, mainly the response method adopted by the transponder in the radio frequency identification system that has realized the "time slot ALOHA" frame access, and the structure of the transponder The schematic diagram is shown in Figure 1B, and the method specifically includes the following steps:

Step 210, receiving a Query command comprising an orthogonal cyclic code with a code length of M; wherein, M is a positive integer;

Step 220: Generate an orthogonal spread spectrum code according to the orthogonal cyclic code, and use the orthogonal spread spectrum code to perform spread spectrum modulation on the response identifier to generate a response signal;

Step 230, sending the response signal;

Step 240, judging whether the Ack command is received, if so, enter the confirmation state, otherwise execute step 250;

Step 250, judge whether to receive the AdjustQuery command, if so, then perform the identification of the next frame

In the above step 210, the query command may not include the shift value N, and the responder defaults the shift value N to M-1 according to the code length M of the orthogonal cyclic code, or the responder may determine whether the query command includes a shift value Value N, if there is no shift value N, the default shift value N is equal to M-1 according to the code length M of the orthogonal cyclic code, otherwise the shift value N is adopted.

In the above-mentioned step 220, the specific implementation of the transponder generating the orthogonal spread spectrum code according to the received orthogonal cyclic code is: the transponder determines the shift offset RN_m according to the shift value N, and the shift offset RN_m is A non-negative integer less than or equal to the shift value N, using the received M-bit orthogonal cyclic code as a prototype spreading code, and shifting RN_m bits to generate the transponder's own orthogonal spreading code. Alternatively, the responder can also randomly generate an integer to shift the orthogonal cyclic code to obtain the spreading code.

In addition, in step 220, before the transponder performs spread-spectrum modulation on the response identifier, it may further include the step of performing Miller code modulation on the response identifier, and then the responder performs spread-spectrum modulation on the modulated response identifier to generate a response signal, The purpose of first performing Miller code modulation on the response mark is to make the data a bipolar code that is beneficial to collision detection.

The step of sending the response signal in the above-mentioned step 230, in the radio frequency identification system that has realized "time slot ALOHA", both the Query command and the AdjustQuery command include the frame length parameter of the started query frame, and the specific implementation method is:

Step 230a, generating frame time slot parameters according to the frame length parameters of the current frame;

Step 230b, judge whether the frame time slot parameter is equal to 0, if so, then execute step 230d, otherwise execute step 230c;

Step 230c, judge whether to receive Requery command, if so, then frame time slot parameter is subtracted 1, and execute step 230b, otherwise execute step 250;

Step 230d, sending a response signal.

The above-mentioned frame time slot parameter is the random number of the "time slot ALOHA" frame time slot, and the size of the frame time slot parameter is in the range of (0, L-1), wherein L represents the frame length of the "time slot ALOHA" protocol, that is, the Query command parameter and the frame length parameter included in the AdjustQuery command, and the frame time slot parameter is used to randomly select a time slot in a frame of the ALOHA protocol for sending data. In the above step 230c, the ReQuery command is the command to start the query again. After the responder receives the command, it adjusts the sending state of the responder, reduces the frame time slot parameter by 1, and continues to judge whether it is satisfied to send the response in the current time slot. Signal.

In the above step 230, during the process of sending the response signal, the transponder also performs necessary processing on the response signal, such as carrier modulation, for transmission. This is common knowledge of those skilled in the art and will not be repeated here.

In the above step 240, after the transponder enters the confirmation state, it means that it has been successfully recognized by the reader, and it can no longer accept the anti-collision recognition, and perform subsequent data exchange, so the following steps can be included:

Step 240a, the responder receives the Read command, and judges whether the response identifier is included, and if so, executes step 240b, otherwise executes step 240c;

Step 240b, the responder judges whether the response identifier is consistent with its own response identifier, and if so, executes step 240c;

In step 240c, the transponder uses the generated orthogonal spread spectrum code to modulate the application data to be sent, and then sends it.

In the above-mentioned step 250, the AdjustQuery command is used as a command to start querying again, and includes the frame length parameter of the next frame, which can adjust the sending state of the transponder, that is, adjust the frame length parameter of the current frame, regenerate the frame time slot parameter, and perform the next step. Frame identification, ie continue to execute step 230 . However, if the transponder enters the waiting state and does not receive the AdjustQuery command, it will always be in the waiting state, and may receive a new round of RFID Query commands, including the orthogonal cyclic code and the frame length parameter of the current frame, then reply The device has entered a new round of radio frequency identification.

The advantage of the first embodiment of the radio frequency identification response method of the present invention is that by using an orthogonal cyclic code with good autocorrelation performance and cross correlation performance as the prototype code of the spread spectrum modulation, the parallel identification of multiple RFID radio frequency identification transponders is realized. The simple anti-collision method based on the "time slot ALOHA" frame reduces the identification time and can realize the rapid identification of a large number of RFID transponders. Since the present invention adopts the self-circulation orthogonal principle of the orthogonal cyclic code to generate the spread spectrum sequence, the The manufacturing cost of the transponder is within the allowable range, which is easy to realize by adopting mainstream chip technology at home and abroad. Moreover, the response method of the present invention updates the frame length of the current frame according to the received AdjustQuery command, can adapt to the identification situation, and adjusts the time for the responder to wait for a randomly determined time slot cyclically to send data.

The second embodiment of the radio frequency identification response method of the present invention is roughly the same as the first embodiment of the response method, the difference is that step 250 is specifically: the responder judges whether the received parameters include the new orthogonal cyclic code and the frame length of the next frame parameter and shift value N of the AdjustQuery command, if so, update the previously adopted orthogonal cyclic code and shift value N with the new orthogonal cyclic code and shift value N, and update the current frame with the frame length parameter of the next frame Frame length parameter, and execute step 220, regenerate shift offset RN_m, from generating new orthogonal spread spectrum code, if not including new orthogonal cyclic code and shift value N, then directly execute step 230, apply The original orthogonal spread spectrum code, spread spectrum modulates the response identifier, and then sends it to enter the identification of the next frame. The parameters of the above AdjustQuery command may contain any combination of orthogonal cyclic code, shift value N and frame length parameters, and the responder updates the current orthogonal cyclic code and/or shift value N and/or or the frame length parameter.

The advantage of the above embodiment is that: the AdjustQuery command received by the transponder not only includes the frame length parameter, but also includes a new orthogonal cyclic code and a shift value N, and the length of the orthogonal cyclic code is set by the reader according to specific conditions. Certainly, the time consumption of the whole recognition process can be adjusted.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be The scheme shall be modified or equivalently replaced without departing from the spirit and scope of the technical scheme of the present invention.

Claims (7)

1. A radio frequency identification reading method, comprising the steps of: Step 11, the reader sets the orthogonal cyclic code with code length M as the current orthogonal cyclic code in the parameter of the query command, and determines the shift value N according to the code length M, and the shift value N is less than the code length A non-negative integer of length M, and the shift value N is set in the parameter of the query command, and the query command is sent; wherein, M is a positive integer; Step 12, the reader generates an orthogonal despreading code according to the current orthogonal cyclic code and the shift value N; Step 13, the reader uses the orthogonal despreading code to despread the received one or more response signals to obtain a response identifier; Step 14, the reader sends an acknowledgment command including the response identifier; Step 15, the reader judges whether the current frame is over, and if so, executes step 16; Step 16, the reader re-determines the current orthogonal cyclic code and/or re-determines the shift value N, and sets it in the parameter of the query adjustment command, sends the query adjustment command, and executes step 12. 2. The radio frequency identification reading method according to claim 1, characterized in that: the step of determining the shift value N is specifically: the reader calculates the number of unidentified transponders, and determines the shift value N according to the calculation result ; Or determine that the shift value N is equal to M-1. 3. The reading method of radio frequency identification according to claim 1, is characterized in that, also comprises: the reader calculates the quantity of unrecognized transponders, and determines the code length M of described orthogonal cyclic code according to calculation result, Orthogonal cyclic codes are selected from the set of orthogonal cyclic codes. 4. The radio frequency identification reading method according to claim 1, characterized in that: the reader also calculates the number of unidentified transponders, and re-determines the frame length parameter in the query command or query adjustment command parameter according to the calculation result . 5. A radio frequency identification answering method, comprising the steps of: Step 21, the responder receives an inquiry command containing an orthogonal cyclic code with a code length of M, wherein M is a positive integer, and judges whether the inquiry command includes a shift value N, if not, then determines the shift according to the code length M The value N is equal to M-1, where N is a non-negative integer; Step 22, the transponder generates an orthogonal spread spectrum code according to the orthogonal cyclic code, and uses the orthogonal spread spectrum code to perform spread spectrum modulation on the response identifier to generate a response signal; Step 23, the responder sends the response signal; Step 24, the transponder judges whether the confirmation command is received, if so, enters the confirmation state, otherwise executes step 25; Step 25, the transponder judges whether the query adjustment command is received, and if so, executes identification of the next frame. 6. The radio frequency identification response method according to claim 5, characterized in that: performing the identification of the next frame in the step 25 is specifically: the responder judges whether the query adjustment command includes an orthogonal cyclic code and/or Shift value N, if so, update the currently used orthogonal cyclic code and/or shift value N with the orthogonal cyclic code and/or shift value N in the query adjustment command, and perform step 22, if both If not, go to step 23. 7. The radio frequency identification response method according to claim 5, wherein the step 25 further comprises: the responder updates the frame length parameter of the current frame according to the frame length parameter in the parameters of the query adjustment command.

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