Radio frequency tag anti-collision identification method and system
The problem of insufficient anti-collision effect of existing RFID systems in the case of a large number of tags is solved by activating RFID tags through light triggering and combining with other trigger processing steps, and achieving more efficient tag identification and anti-collision effect.
Patent Information
- Application Number
- CN202411582605.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-07
- Publication Date
- 2025-02-18
AI Technical Summary
The existing RFID system has poor anti-collision effect in a large number of tags, and there are problems such as missed reading and complex and time-consuming signaling processes.
Activate the RF tag through light triggering, combined with other trigger processing steps, reduce the number of tags to be responded to, improve the anti-collision effect and identification efficiency.
It greatly improves the anti-collision effect and recognition efficiency of RF tags, correctly recognizes tags, and reduces the recognition failure rate and error rate.
Smart Images
Figure CN119476321A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of radio frequency identification technology, and in particular to a radio frequency tag anti-collision identification method and system. Background Art
[0002] RFID (Radio Frequency Identification) technology, also known as electronic tag technology, is a non-contact automatic identification technology. Its basic working principle is to use the transmission characteristics of radio frequency signals and inductance or electromagnetic space coupling to achieve automatic identification of the identified object. RFID system generally consists of two parts: RFID electronic tag (Tag) and reader (Reader).
[0003] The basic working process is as follows: the electronic tag reader sends a radio frequency signal of a specific working frequency through the radio frequency transmitting antenna. When the electronic tag enters the working coverage area of the reader's transmitting antenna, its antenna generates an induced current through inductance or electromagnetic space coupling, activating the passive tag; part of the energy obtained by the tag is rectified into a DC power supply and provided to the electronic circuit in the tag for operation, and the other part is modulated by the data information stored in the tag and reflected back to the tag reader through the tag antenna; the tag reader receives the carrier signal reflected back from the electronic tag through the receiving antenna, demodulates and decodes the received signal, obtains the identification data information stored in the electronic tag, and sends the identification data information to the computer application system through the communication interface for processing.
[0004] There are usually multiple electronic tags in the RFID radio frequency field. If no anti-collision measures are taken, these tags will receive the electromagnetic waves emitted by the reader at the same time and send information to the reader at the same time. The information received by the reader will interfere with each other, that is, there will be a conflict problem. The basic methods to solve the conflict problem include the time-slot ALOHA algorithm and the split algorithm. ISO18000-6C uses the time-slot ALOHA algorithm, which is the most commonly used method of anti-collision algorithm.
[0005] The RFID system uses the ALOHA algorithm to avoid collisions, allowing tags and readers to communicate quickly and reliably, reducing recognition failure and error rates, and improving the efficiency of the RFID system. However, the ALOHA algorithm also has the following disadvantages: (1) The Aloha algorithm has poor anti-collision effect when there are a large number of tags. When the number of tags involved in the collision is large, the anti-collision process is long and the probability of multiple tags responding at the same time increases.
[0006] (2) The Aloha algorithm has the problem of missed reading. When a tag collides, it is not correctly read. If the number of tags is large, the tag may not be correctly identified for a long time, and the system may mistakenly judge that it is not in the identification area.
[0007] (3) The signaling process of the Aloha algorithm is complex and time-consuming. The reader and the tag need to interact with each other through multiple commands to identify the tag EPC. Summary of the invention
[0008] In view of the shortcomings of the prior art, the object of the present invention is to provide a radio frequency tag anti-collision identification method and system to improve the tag anti-collision effect and correctly identify the tag.
[0009] To achieve the above object, the present invention can be implemented through the following technical solutions: A radio frequency tag anti-collision identification method, comprising: Receive the RF carrier sent by the reader and enter the idle state after power-on; Detecting a light triggering event and performing a trigger processing step; Respond tag information to the reader.
[0010] Furthermore, before responding to the tag information to the reader / writer, the method further includes: Receive the instruction sent by the reader / writer.
[0011] Furthermore, the step of detecting a light triggering event and performing a triggering process includes: A light-triggered event is detected; Set the light trigger detection status flag; The designated addresses of the tag EPC area are respectively ORed with the light trigger detection status flag bit; When responding to the reader with tag information, the calculated EPC value is reported.
[0012] Furthermore, the step of detecting a light triggering event and performing a triggering process includes: A light-triggered event is detected; Enter the state of waiting to receive custom instructions; When waiting to receive custom commands, if the light trigger event disappears, it returns to the idle state; When in the state of waiting to receive a custom instruction, if a custom instruction is received, the state of responding to the custom instruction will be entered; After completing the response to the custom command, the state returns to the waiting state for receiving the custom command.
[0013] Furthermore, the step of detecting a light triggering event and performing a triggering process includes: Pre-set the initial value of the number of tag responses; Detect the current response times of the tag; If the tag's current response times are not zero, a light triggering event is detected; If a light trigger event is detected, the system enters the receiving command state. After receiving the command in the receiving command state, the system enters the response state. If the receiving command times out in the receiving command state, the system returns to the idle state. After the response is completed, the response count is reduced by one and the state returns to the idle state; If no light trigger event is detected, it returns to the idle state.
[0014] Furthermore, the step of detecting a light triggering event and performing a triggering process includes: Pre-set the initial value of the number of tag responses; A light-triggered event is detected; Detect the current response times of the tag; If the tag's current response times are not zero, the tag enters the active response state and responds to the reader with tag information; After the response is completed, the tag enters the state of waiting to receive the reader's response ACK; If the tag receives an ACK from the reader, the tag sets the response times to zero and returns to the idle state; If the tag receives the ACK from the reader for a timeout, it enters the waiting for response state; After waiting for the preset waiting response time, the tag determines whether the value of the number of responses within the cycle is zero; if it is zero, it returns to the idle state; if it is not zero, the number of responses is reduced by one, and the tag responds to the reader again.
[0015] Furthermore, the tag receives and responds to custom commands in an idle state.
[0016] Further, each time the tag detects a light triggering event, the number of responses is reset to an initial value. Further, each time the tag detects a light triggering event, the number of light triggering is updated, and the number of light triggering is increased by one.
[0017] A radio frequency tag anti-collision identification system comprises a tag and a reader / writer, wherein the tag applies any of the above identification methods.
[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention activates the radio frequency tag through light triggering, greatly reducing the number of tags to be responded to, and combined with other trigger processing steps, improving the anti-collision effect, recognition efficiency and accuracy of the radio frequency tag. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a method flow chart of the prior art; Figure 2 is a flow chart of one implementation of the identification method of the present invention; Figure 3 is a flow chart of one implementation of the identification method of the present invention; Figure 4 is a flow chart of one implementation of the identification method of the present invention; Figure 5 is a flow chart of one implementation of the identification method of the present invention; Figure 6 It is a flow chart of one implementation of the identification method described in the present invention. DETAILED DESCRIPTION
[0020] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods. The terms such as "upper", "inner", "middle", "left", "right" and "one" cited in this specification are only for the convenience of description, and are not used to limit the scope of the present invention. The change or adjustment of their relative relationship shall also be regarded as the scope of the present invention without substantially changing the technical content.
[0021] like Figure 1 As shown, the identification steps of the photosensitive label in the prior art are: The tag is powered on after entering the electric field, and then immediately performs photosensitivity detection; If light is detected, the flag is saved to address 127 in the user area, and the data is 0x0202; If no light is detected, the data in the user area is kept, and the default value is 0x00; Then it enters the normal 6C mode to send and receive commands; In normal 6C mode, the reader sends a read command, and the tag responds to the read command by sending the 127th address data of the user area of the tag to the reader to determine whether the tag detects light.
[0022] During the power-on period, the tag only performs one photosensitive detection. After the detection is completed, it will not be detected again. That is to say, the data stored in the address 127 of the user area will only be updated once during the power-on period. After the detection is completed, no matter how the light changes during the power-on period, it will not cause the flag data to change, unless the tag is powered off and then powered on again to detect again.
[0023] The radio frequency tags described in the present invention are all light-triggered tags, that is, radio frequency tags whose activation signal is a light signal.
[0024] like Figure 2As shown, it is one of the implementation methods of the radio frequency tag anti-collision identification method of the present invention, which is a 6C plus flag bit detection mode: The reader sends a radio frequency carrier to provide power to the tag. The tag receives the radio frequency carrier sent by the reader and enters the idle state after powering on. When the tag receives the 6C command from the reader in the idle state, it enters the 6C command processing state; If the command processing is successful, it enters the response command state, if the command processing fails, it returns to the idle state; When the tag detects a light trigger event in the idle state, the light trigger detection state flag is set, that is, the light trigger detection state flag is assigned a value of 1; After the flag is set, it returns to the idle state; The specified address of the tag EPC area is respectively ORed with the light trigger detection status flag bit; When the reader counts the tags, the tags report the EPC value after the above calculation when responding to the tag information to the reader, so that the reader can obtain the light trigger detection status of the tag. The light trigger detection status flag is not saved when the power is off. The photosensitive tag in the prior art is similar to a sensor, which only detects whether there is light. The reader needs to send a read instruction to obtain the 127th address data of the tag user area to determine whether the tag detects light. This mode uses the tag light trigger detection status flag to participate in the calculation, and the calculation result is reported along with the EPC value when responding to the tag information to obtain the light trigger detection status of the tag. This mode saves the process of knowing the light trigger status and improves the efficiency of tag recognition. At the same time, because the tag is activated by light triggering, only the tag with the light trigger detection status flag bit in position can respond to the reader through the 6C instruction, which greatly reduces the number of tags to be responded to, prevents cross-reading, and thus improves the anti-collision effect. In scenarios such as baggage transportation, logistics sorting, and factory assembly lines, the reader obtains the light trigger detection status of the tag so that the staff can know when the tag passes a certain location.
[0025] The light trigger detection status flag is initialized to a reset state when powered on. When the tag is powered on, the flag is set after a light trigger is detected, and then the flag state is maintained until the tag is powered off. During this period, the flag is not reset after the light trigger event disappears.
[0026] like Figure 3 As shown, it is one of the implementation methods of the radio frequency tag anti-collision identification method of the present invention, which is a responsive light trigger mode: The reader sends a radio frequency carrier to provide power to the tag. The tag receives the radio frequency carrier sent by the reader and enters the idle state after powering on. In the idle state, the tag immediately enters the state of waiting to receive custom commands after detecting a light trigger event; When the tag is waiting to receive a custom command, if the light trigger event disappears, it returns to the idle state; When the tag is in the state of waiting to receive a custom instruction, if it receives a custom instruction, it enters the state of responding to the custom instruction; The tag receives custom instructions from the reader; The tag responds to the reader with tag information; After the tag completes responding to the custom command, it returns to the state of waiting to receive the custom command.
[0027] After the tag is powered on, it enters the idle state. In the idle state, continuous light triggering events are required to keep the tag in the waiting for custom instructions state. Otherwise, the tag returns to the idle state and waits to receive the get_id and set_reg custom instructions in the waiting for custom instructions state. The get_id and set_reg commands use the command fields reserved for manufacturers to customize in the 6C protocol.
[0028] The reader sends custom instructions to all tags within the working range, but only tags triggered by light will enter the state of waiting to receive custom instructions and send the tag's identification to the reader. The content of the custom instructions sent by the reader includes the frame header, information field and check code field. Correspondingly, the tag's response content in response to the custom instructions sent by the reader includes the frame header, information length, information field and check code field. The frame header uses the user-defined instruction field in the general RFID protocol, so it complies with the general RFID protocol and will not conflict with other instructions in the general RFID protocol. The information field is custom content, the check code field can verify the correctness of the entire instruction, and the information length can verify the integrity of the entire instruction. In this way, the reader can identify the tags of this system, avoid confusion with tags of other systems, and improve the accuracy of reading.
[0029] The light trigger detection status flag is initialized to a reset state when powered on, that is, the light trigger detection status flag is assigned a value of 0; during the power-on period of the tag, the light trigger status is detected in real time, and the flag is set after a light trigger event is detected, that is, the light trigger detection status flag is assigned a value of 1; the flag is reset after the light trigger event disappears.
[0030] This mode activates tags through light triggering, greatly reducing the number of tags waiting to respond. Then, through custom instructions, only tags that receive custom instructions can respond to the reader. This not only prevents the reader from identifying tags that are not part of this system, but also specifies the tags to be responded to, replacing the anti-collision mechanism of 6C and greatly improving the anti-collision recognition capability of tags.
[0031] like Figure 4 As shown, it is one of the implementation methods of the radio frequency tag anti-collision identification method of the present invention, which is a command light trigger mode: Pre-set the initial value of the tag response counter. You can use the 6C command or a custom command to set it. The initial value is usually not zero. The reader sends a radio frequency carrier to provide power to the tag. The tag receives the radio frequency carrier sent by the reader and enters the idle state after powering on. The tag detects the current value of the counter in the idle state and obtains the current number of responses. If the current number of responses is zero, the tag remains in the idle state. If it is not zero, the tag enters the light-triggered detection state. In the light trigger detection state, if a light trigger event is detected, the command receiving state is entered, and if no trigger is detected, the idle state is returned; In the command receiving state, the tag enters the response state when receiving a command, and returns to the idle state when the reception times out; After responding to the command, the tag decrements the number of responses by one and returns to the idle state.
[0032] A tag with zero response times indicates that the tag has been read by the reader. This mode first determines the response times and then detects the light trigger, excluding tags that have been read by the reader. Only tags that have not responded to the reader are light-triggered, further reducing the number of tags to be responded to, thereby optimizing the effect of tag anti-collision recognition.
[0033] like Figure 5 As shown, it is one of the implementation methods of the radio frequency tag anti-collision identification method of the present invention, which is a direct light trigger mode: The reader sends a radio frequency carrier to provide power to the tag. The tag receives the radio frequency carrier sent by the reader and enters the idle state after powering on. The tag can receive and respond to custom instructions in the idle state. The custom instructions can be used to switch the tag to other modes or configure parameters. After responding to the custom instructions, the tag returns to the idle state. Pre-set the initial value of the number of tag responses, which is usually not zero; When the tag detects a light triggering event in the idle state, it detects the current response times. If the response times in the current cycle are not zero, it immediately enters the active response state. In the active response state, the tag actively responds to the reader with tag information; After the response is completed, the tag enters the state of waiting for the reader to respond ACK. ACK is the confirmation character. In data communication, a transmission control character sent by the receiving station to the sending station indicates that the sent data has been confirmed to be received correctly. If the tag receives a response ACK from the reader while receiving ACK, it will clear the response counter and set the response times to 0. After clearing, the tag returns to the idle state. If the tag does not receive the response ACK sent by the reader within the time limit while receiving the ACK, it will enter the state of waiting for the response. When the tag is in the waiting response state, after the delay waiting response time (pre-set), it determines whether the value of the response counter in the cycle is zero. If it is zero, the tag returns to the idle state. If it is not zero, the value of the response counter is reduced by one and re-enters the active response state, and actively responds to the tag information to the reader again until the tag receives the reader's response ACK or the value of the response counter is reduced to 0. For example, if the initial value of the response counter is set to 5, the tag will actively report the tag information to the reader at most 5 times. If the reader's response ACK is received in the middle, the tag will immediately stop actively reporting. There is a time interval for waiting for ACK between each report, and this time interval is the preset waiting response time. The waiting response time is set by the write instruction of the 6C instruction or the custom set_reg instruction.
[0034] The light trigger detection status flag is initialized to the reset state when powered on, that is, the light trigger detection status flag is assigned to 0; during the power-on period of the tag, after the light trigger is detected, the flag is set, that is, the light trigger detection status flag is assigned to 1, and then the flag state is maintained until the tag is powered off. During this period, the flag is not reset after the light trigger event disappears.
[0035] The tag actively reports its identification using the 6C command to respond to the ACK response. The tag receives the ACK of the reader using the ACK command of the 6C command. However, the differences from the 6C protocol are that first, the response timing of ACK and ACK is reversed, and secondly, the random number field in ACK is not RN16, but the tag CRC-16 reported by the tag.
[0036] During the identification process, the tag in this mode first detects the light trigger and the response times are not zero, and then actively responds to the tag information. This is equivalent to the designated tag responding to the reader, replacing the anti-collision mechanism of 6C. This can quickly identify the tag, avoid simultaneous identification of multiple tags, and improve the tag's anti-collision capability and recognition accuracy.
[0037] like Figure 6 As shown, it is one of the implementation modes of the radio frequency tag anti-collision identification method of the present invention, which is a light-triggered counting mode: The reader sends a radio frequency carrier to provide power to the tag. The tag receives the radio frequency carrier sent by the reader and enters the idle state after powering on. In the idle state, if the tag detects a light triggering event, it will increment the light triggering counter by one and reset the response times counter to the initial value. Pre-set the initial value of the number of tag responses, which is usually not zero; When the tag detects a light trigger event in the idle state, it detects the value of the response counter. If the value of the response counter is not zero, the tag actively responds to the reader with tag information. The response content includes the tag ID and the current value of the tag light trigger counter. After the tag completes the response, the value of the response counter is reduced by one, and the tag enters the state of waiting for the reader to respond with ACK. ACK is an acknowledgment character. In data communication, a transmission control character sent by the receiving station to the sending station indicates that the sent data has been confirmed to be received correctly. When the tag is waiting to receive the reader's ACK, if it receives the reader's ACK within the specified time, it will set the response times to zero and return to the idle state. When the tag is waiting to receive the reader's response ACK, if it does not receive the reader's response ACK within the timeout period, it will enter the waiting response state. In the waiting response state, after the delay waiting response time (pre-set), the tag will determine whether the value of the response counter in the cycle is zero. If it is zero, the tag will return to the idle state. If it is not zero, the value of the response counter will be reduced by one and re-enter the active response state, and actively respond to the tag information to the reader again until the tag receives the reader's response ACK or the value of the response counter is reduced to 0. For example, if the initial value of the response counter is set to 5, the tag will actively report the tag information to the reader at most 5 times. If the reader's response ACK is received in the middle, the tag will immediately stop actively reporting. There is a time interval for waiting for ACK between each report, and this time interval is the preset waiting response time. The waiting response time is set by the write instruction of the 6C instruction or the custom set_reg instruction.
[0038] In this mode, the tag enters the idle state after powering on. In the idle state, each time a light trigger event is received, the light trigger counter is updated and added by one. The value of the light trigger counter is saved when the power is off. By adding the function of the light trigger counter, the number of times the tag is triggered by light can be calculated. It can be applied in logistics sorting and factory assembly lines. When the tag enters each interval, it will be exposed to light once, and the value of the trigger counter will change. In other words, the value of the light trigger counter of the tag in different intervals is different. In this way, a reader can be deployed in each interval. The reader can distinguish and identify according to the value of the light trigger counter. Each reader only reads the tags in its own interval and will not read the tags in other intervals, which is convenient for quickly and accurately identifying the tags in this interval and preventing tag recognition conflicts between intervals. However, the existing readers have no way to make the boundaries very clear. They can only distinguish by widening the interval between each interval, adjusting the radiation range of the antenna, adjusting the power of the reader, etc., but this still cannot prevent tag recognition conflicts between intervals.
[0039] After the tag is successfully read by the card reader in the previous interval, the response times will be cleared, and the tag identification needs to be re-reported to enter the next interval, so the count value of the response times counter needs to be reset before the next light trigger. Therefore, after each light trigger event, the tag resets the value of the response times counter and resets the response times to the initial value, so that each time it enters a new interval, the response times of the tag can be re-read. The light trigger counter is a 16-bit counter, and the response times counter is a 12-bit counter.
[0040] In the idle state, the tag can receive the set_reg custom instruction, through which the initial value of the tag's light-triggered counter in this mode and the initial value and reset value of the tag's response times (the same value) can be set. The tag can also be switched to other modes and return to the idle state after responding to the custom instruction.
[0041] In the tag response state, the response information includes the tag identification, the light-triggered counter value and the check code. When the reader responds ACK, the ACK contains the check code information reported by the tag. After the tag receives the ACK from the reader, it determines whether the check code is consistent with the one reported by itself. If so, it considers that the ACK has been received, otherwise it continues to wait for the ACK until timeout.
[0042] During the identification process, the tag in this mode first detects the light trigger and the response times are not zero, and then actively responds to the tag information, which is equivalent to the designated tag responding to the reader, replacing the anti-collision mechanism of 6C. This can quickly identify the tag, avoid identifying multiple tags at the same time, and improve the anti-collision ability and recognition accuracy of the tag. At the same time, it has the functions of updating the light trigger times and resetting the response times, increasing the identification boundary, further improving the anti-collision ability, and is more suitable for applications in various scenarios.
[0043] A radio frequency tag anti-collision identification system includes a tag and a reader / writer. The tag uses the identification method of any of the above modes, and can also switch from one mode to another mode for identification. The system can also include a computer application system for displaying which tags the reader / writer has identified.
[0044] The radio frequency tag anti-collision identification method and system of the present invention are different from the photosensitive tags in the prior art. The photosensitive tags in the prior art are similar to a sensor that only detects whether there is light. The present invention uses light-triggered events to participate in the identification process, thereby improving and optimizing the anti-collision identification capability of the tag.
[0045] The implementation methods of the present invention are not limited to this. According to the above content of the present invention, using common technical knowledge and customary means in the field, without departing from the above basic technical ideas of the present invention, the present invention can also make other various forms of modification, replacement or combination, all of which fall within the scope of protection of the present invention.
Claims
1. A radio frequency tag anti-collision identification method, characterized in that: include: Receive the RF carrier sent by the reader and enter the idle state after power-on; Detecting a light triggering event and performing a trigger processing step; Respond tag information to the reader.
2. The radio frequency tag anti-collision identification method according to claim 1, characterized in that: Before responding to the tag information to the reader / writer, the method further includes: Receive the instruction sent by the reader / writer.
3. The RFID tag anti-collision identification method according to claim 2, characterized in that: The step of detecting a light triggering event and performing a triggering process comprises: A light-triggered event is detected; Set the light trigger detection status flag; The designated addresses of the tag EPC area are respectively ORed with the light trigger detection status flag bit; When responding to the reader with tag information, the calculated EPC value is reported.
4. The radio frequency tag anti-collision identification method according to claim 2, characterized in that: The step of detecting a light triggering event and performing a triggering process comprises: A light-triggered event is detected; Enter the state of waiting to receive custom instructions; When waiting to receive custom commands, if the light trigger event disappears, it returns to the idle state; When in the state of waiting to receive a custom instruction, if a custom instruction is received, the state of responding to the custom instruction will be entered; After completing the response to the custom command, the state returns to the waiting state for receiving the custom command.
5. The radio frequency tag anti-collision identification method according to claim 2, characterized in that: The step of detecting a light triggering event and performing a triggering process comprises: Pre-set the initial value of the number of tag responses; Detect the current response times of the tag; If the tag's current response times are not zero, a light triggering event is detected; If a light trigger event is detected, the system enters the receiving command state. After receiving the command in the receiving command state, the system enters the response state. If the receiving command times out in the receiving command state, the system returns to the idle state. After the response is completed, the response count is reduced by one and the state returns to the idle state; If no light trigger event is detected, it returns to the idle state.
6. The radio frequency tag anti-collision identification method according to claim 1, characterized in that: The step of detecting a light triggering event and performing a triggering process comprises: Pre-set the initial value of the number of tag responses; A light-triggered event is detected; Detect the current response times of the tag; If the tag's current response times are not zero, the tag enters the active response state and responds to the reader with tag information; After the response is completed, the tag enters the state of waiting to receive the reader's response ACK; If the tag receives an ACK from the reader, the tag sets the response times to zero and returns to the idle state; If the tag receives the ACK from the reader for a timeout, it enters the waiting for response state; After waiting for the preset waiting response time, the tag determines whether the value of the number of responses within the cycle is zero; if it is zero, it returns to the idle state; if it is not zero, the number of responses is reduced by one, and the tag responds to the reader again.
7. The RFID tag anti-collision identification method according to claim 6, characterized in that: The tag receives and responds to custom commands in idle state.
8. The RFID tag anti-collision identification method according to claim 6, characterized in that: Each time the tag detects a light trigger event, it resets the response count to the initial value.
9. The radio frequency tag anti-collision identification method according to claim 7, characterized in that: Each time the tag detects a light triggering event, the light triggering count is updated and the light triggering count is increased by one.
10. A radio frequency tag anti-collision identification system, comprising a tag and a reader / writer, characterized in that: The label is applied with the identification method described in any one of claims 1 to 9.