KR100881865B1 - Multi tag recognize method using virtual group root node and dynamic tag answering function - Google Patents

Abstract

A multi-tag recognition method using a virtual group root node and a dynamic tag response function is provided to minimize power consumption of a tag and correctly recognize the tags found in a recognition area of a tag reader regardless of the number by optimizing the number of cases for searching around a terminal node through the dynamic tag response function. A tag reader recognizes a plurality of terminal tag nodes derived from each virtual group root node by successively selecting the virtual group root node and utilizing the dynamic response function assigned to the tag. A reader data frame and a tag data frame are transceived between the tag reader and the tag. A pointer points a position of at least one bit included in a tag ID requested by the tag reader.

Description

Multi tag recognize method using virtual group root node and dynamic tag answering function}

The present invention relates to a method for recognizing a tag, and more particularly, to a multi-tag recognition method for recognizing a plurality of tags existing in a recognition area of an RFID tag reader accurately, quickly and efficiently. will be.

A radio frequency identification system, or RFID system, is generally divided into three parts: a tag reader, a tag, and an operation software & network.

The tag contains the unique information of the thing, the tag reader identifies the tag by contact or contactless through the radio signal to process the information related to the tag, the operating software and the network processes the information to another processor (processor) It performs the function of linking with.

The RFID tag can be classified into an active type and a passive type according to a power supply method supplied to the tag. Active tags use built-in power, such as batteries, and passive tags are powered from electromagnetic fields radiated from a tag reader. Active tags have the advantage of being far from tag readers, but they have limitations in that they have a built-in battery. That is, when the built-in battery is discharged, the tag cannot be operated and the size of the tag becomes large due to the space occupied by the battery. As described above, due to the problem of the active tag, most developers in the RFID application field tend to prefer the passive tag to the active tag.

The most problematic issue when using passive tags is the recognition distance of the tag reader. Since the passive tag is powered from an electromagnetic field radiated from the tag reader, when the tag reader is deviated from the tag reader by a certain distance or more, the passive tag cannot be supplied at all or cannot be supplied with the minimum power required. In addition, the amount of power that can be transmitted to the tag through the electromagnetic field radiated from the tag reader is constant, and the tag transmits the information required by the tag reader to the tag reader with a certain power consumption using the power received from the electromagnetic field. The recognition distance between the tag reader and the tag is determined depending on whether it can be done.

The tag which enters into the recognition region of the tag reader and collects power above the limit power from the electromagnetic field radiated from the tag reader, transmits the information desired by the tag reader, that is, information stored in the tag, to the tag reader. When the tag sends the tag reader to the tag reader the information required by the tag, it basically consumes a certain amount of power, and the distance between the tag and the tag reader is increased by minimizing the power that the tag must consume. . Therefore, the developer of the RFID system needs to develop a method for minimizing the power consumption of the tag in the tag recognition process of the tag reader.

If the tag reader has a large number of tags to read, multi-tag recognition speed is also a technical area to be considered by the RFID system designer. That is, when there are a plurality of tags in the recognition region of any one tag reader, the multi-tag recognition speed that defines how fast and accurately the tag reader can recognize all the tags in the recognition region determines the performance of the RFID system. This is one of the very important indicators. Currently, a method for minimizing the power consumption of a tag and maximizing the tag recognition speed in a tag multi tag recognition process is proposed.

The most representative ones are binary tree protocol and query tree protocol.

The binary tree protocol is a method in which a tag reader recognizes a tag by exchanging one tag information with all tags in its recognition area, and the tag has a pointer. At that time, if one bit is compared and one tag is identified, it must be started from the beginning again.The information obtained in the process of recognizing one tag is not used for the recognition step to find the next tag. will be.

One of the methods to compensate for this is the query tree protocol. In the query tree protocol, tags are determined by repeating a process of comparing a question sent from a reader without a pointer. However, there is a problem in that the query tree protocol has a lower performance than a binary tree protocol.

The Korean Intellectual Property Office has been filed with a method for reducing the amount of unnecessary information of the query tree protocol while compensating for the disadvantages of the binary tree protocol. [KR 10-0728306] A "wireless" based on the depth-first search technique The tag collision prevention method for frequency identification "is to use the previous information obtained by the tag reader in finding one tag in the subsequent process of finding another tag. The protocol does not indicate the location of the collision node as a sequence of tag IDs as in the conventional query tree protocol, but decodes the location of the collision node to the height of the binary tree structure and sends it to the tag.

The protocol based on the depth-first search technique clearly solves the problems of the conventional protocols introduced above. However, the protocol based on depth-first search is more efficient than the previous two protocols in processing a large number of tags in the recognition area. The disadvantage is that the performance is not superior to other conventional protocols.

The technical problem to be solved by the present invention is to provide a multi-tag recognition method that can quickly and accurately recognize all tags regardless of the number of tags existing in the recognition area of the tag reader to minimize the power consumption of the tag. .

According to an aspect of the present invention, there is provided a method for recognizing a multi-tag, which includes defining a virtual grouping root node and recognizing a plurality of terminal tag nodes.

≤k≤2ⁿ을 만족하는 예상태그 수

(

는 정수)를 정의하고, 각각

개의 비트로 구별할 수 있는

개의 가상 집단화 근 노드를 정의한다. 상기 복수 개의 단말태그노드를 인식하는 단계는 태그판독기가 상기

개의 가상 집단화 근 노드를 순차적으로 선택하여, 태그에 부여된 동적응답기능을 활용하여 각각의 가상 집단화 근 노드로부터 파생되는 복수 개의 단말태그노드를 인식한다. 여기서 n(n은 정수)은 태그 내에 저장되어 있는 태그의 고유ID의 비트 수, k(k는 정수)는 태그판독기 인식영역 내에 있는 실제 태그의 수를 의미한다. The defining of the virtual grouping root node is 1≤

Example of states that satisfy ≤ k ≤ 2 ⁿ

(

Is an integer), and each

Distinguishable by four bits

Defines virtual clustering root nodes Recognizing the plurality of terminal tag nodes, the tag reader is

The virtual grouping root nodes are sequentially selected to recognize a plurality of terminal tag nodes derived from each virtual grouping root node by using a dynamic response function attached to a tag. Where n (n is an integer) is the number of bits of the unique ID of the tag stored in the tag, and k (k is an integer) is the number of actual tags in the tag reader recognition area.

In the multi-tag recognition method according to the present invention, since the tag search is started from the virtual grouping root node, the number of cases of searching near the virtual grouping root node is reduced, and at the same time, the dynamic tag response function is used to reduce the number of cases. Optimizing the number of search cases has the advantage of minimizing the power consumption of tags and recognizing tags quickly and accurately regardless of the number of tags present in the tag reader's recognition area.

The core idea of the present invention is to define a first virtual grouping root node, and add a dynamic answering function to the second tag to perform a search of the tag from the virtual grouping root node and The dynamic response function continues to be used.

는 1≤

≤k≤2ⁿ 을 만족하는 하나의 정수 값을 나타낸다. Before describing the virtual grouping root node which is one of the technical ideas of the present invention, some symbols are defined. n denotes the number of bits of the unique ID stored in the tag, k denotes the actual number of tags in the tag reader recognition area, and the estimated numbers of tag.

Is 1≤

One integer value satisfying ≤ k ≤ 2 ⁿ is shown.

에 관한 정보를 알 수 있다고 가정한다. 이러한 가정은 태그를 장착한 물류의 변동이 불연속적으로 바뀌지 않고 물류 관리자의 방침에 따라 예상태그 수

가 결정될 수도 있기 때문에 가능하다. 최악의 경우 태그판독기는

의 값을 1(one)이나 2(two)로 설정하면 된다. In the actual tag recognition process, the tag reader cannot know the number of tags existing in the recognition area in advance. But at least yes

Suppose we can get information about. This assumption is based on the logistics manager's policy without changing the distribution of tagged logistics discontinuously.

This is possible because may be determined. In the worst case, the tag reader

Set the value of to 1 (one) or 2 (two).

개의 태그들을 이진트리 구조의 말단 노드에 고르게 분포 시킨다면, 이진트리 구조는 적어도 하나의 노드를 중심으로 집단화(grouping)가 가능해지게 되는데, 이때 집단화의 시작점을 본 발명에서는 가상 집단화 근 노드(virtual grouping root node)라 부를 것이다. 이 가상 집단화 근 노드는 이진트리 구조에서 그에 해당하는 2진수의 높이정보(m_e)를 가지게 되는데, 상기 높이정보(m_e)에 대응되는 비트 수는 수학식 1과 같이 예상태그 수

를 이용하여 구할 수 있다. If yes

If the four tags are evenly distributed at the end nodes of the binary tree structure, the binary tree structure can be grouped around at least one node, and the starting point of the grouping is the virtual grouping root in the present invention. node will be called. The virtual grouping root node has a binary height information (m _e ) corresponding to the binary tree structure, and the number of bits corresponding to the height information (m _e ) is as shown in Equation (1).

Can be obtained using

Tag readers applying the conventional binary tree protocol and the question tree protocol have started their first inquiry process with only one bit, but in the present invention, the tag reader has the height information (m _e ) of the virtual grouping root node from the beginning. Start your own questioning process with the corresponding bits. Referring to Equation 1, if it is assumed that the number of tags to be recognized is four, it is possible to start your own question process with 2 bits. As will be described later, the number of cases of searching near the virtual grouping near node can be reduced, thereby reducing the search time.

Adding a dynamic response function to a tag, which is one of the technical ideas of the present invention, means that when an arbitrary tag transmits its response information to the tag reader, the response information is transmitted from other tags to the same tag reader. It means to keep sending until it crashes. In order to implement this, the tag reader recognizes a collision of response information transmitted from tags, and instructs each tag to stop transmitting response information after the collision is recognized. This can obtain the effect of optimizing the number of cases of searching near the end node as described later.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 illustrates a data frame exchanged between a tag reader and a tag.

Referring to FIG. 1, a reader data frame transmitted from a tag reader to a tag is shown between a first dotted line and a second dotted line, and S-NULL is a data signal indicating that the data transmission of the tag reader has started. , E-NULL is a data signal indicating that the data transmission of the tag reader is finished, N-NULL is a data signal that serves to distinguish between the 'pointer position' and the 'question bit' signal.

The tag data frame (b) sent from the tag to the tag reader is shown between the second dotted line and the third dotted line, and contains a response (response bit) corresponding to the question (question bit) sent by the tag reader to the tag. . When a plurality of tags existing in the recognition region of the tag reader simultaneously transmits (collisions) its data frame to the same tag reader, it may occur. When the tag reader detects the collision (collision detection), it transmits a stop signal STOP to the tag, which means that it is no longer necessary to transfer data from the tag to the tag reader, and sends the stop signal STOP. The received tag no longer transmits information.

2 is a block diagram of a pointer constituting the inside of a tag.

2, the pointer 200 includes a counter 210, a decoder 220, and a memory device 230.

The tag uses the counter 210 to indicate one or more specific bits of the plurality of bits assigned to its ID. The value CNT output from the counter 210 is decoded by the decoder 220 and used as a pointer value indicating each storage location of the memory device 230 in which a plurality of ID bits of a tag are stored.

The tag matches the pointer position information included in the reader data frame (a) transmitted from the tag reader shown in FIG. 1 with the output value CNT of the counter 210. When the value included in the pointer position information included in the reader data frame A and the output value CNT of the counter 210 match, the tag decodes and decodes the value CNT output from the counter 210. Create a value (DeCNT). The decoded value DeCNT is used as an address of the memory storage 230 and compares a value BN of a bit stored at the address with a question value (question bit) received from a tag reader. When the bit value and the question bit stored at the corresponding address are the same, the tag transmits its ID stored in the next storage area of the storage area in which the BN value of the memory storage device 230 is stored to the tag reader.

3 shows a state diagram of a tag during communication between the tag reader and the tag.

Referring to FIG. 3, the tag has four modes S1 to S4 and is basically in the standby mode S1. When the S-NULL signal included in the reader data frame transmitted from the tag reader to the tag is transmitted to the tag and the tag receives the tag, the tag receives its status from the standby mode (S1) and receives the mode (S2). To change the state. The tag maintains its status in the receive mode (S2) until the E-NULL signal included in the reader data frame transmitted from the tag reader to the tag is received by the tag reader. The tag having the specified data at the specified pointer position changes its state to the transmission mode (S3) when it is received.

In the transmission mode S3, the tag sends the bits constituting its ID to the tag reader until the tag receives the stop signal STOP in the reader data frame. At this time, since the tag increments the value CNT output from the counter 210 by one, each of the bits constituting the ID transmitted to the tag reader will be sequentially transmitted.

The tag which sequentially transmits all the bits constituting its ID until the stop signal STOP is received from the tag reader changes its state to the inactive mode S4. When receiving the stop signal STOP from the tag reader, the tag that has not transmitted its last ID bit changes its state back to the standby mode S1 and waits for the next command.

4 illustrates a tag search tree structure according to an embodiment of the present invention.

Referring to FIG. 4, the tag search tree structure 400 includes a node aggregation unit including a plurality of virtual grouping root nodes 410 and a plurality of end tag nodes derived from each of the virtual grouping root nodes. 420. One virtual set 430 is derived from one of the virtual root node 00 of the virtual grouping root nodes 410 and the virtual root node 00 among tag nodes included in the node set 420. End tag nodes (00000, 00011, 00111) are combined into one set. Therefore, the number of virtual sets 430 will be determined according to the number of virtual grouping root nodes. In the case of FIG. 4, four virtual sets 430 are possible.

Although shown in FIG. 4 as showing a conventional binary tree structure, it is strictly distinguished from the conventional binary tree structure as described later. That is, in the conventional binary tree structure, the tag is searched using one bit, but the tag search tree structure according to the present invention is different in that a plurality of bits can be used at the beginning of the search. In FIG. 4, two bits (00, 01, 10, 11) are used as start bits of the first search.

4 shows that the tag search tree structure is only one embodiment for explaining the concept of the present invention, and if it is logically expanded, the number of virtual grouping root nodes is determined according to the expected number of tag nodes and is used in a system in which a tag reader is used. Will change accordingly.

가 결정될 수도 있기 때문에, 가상 집단화 근 노드의 높이 정보 m_e는 용이하게 결정할 수 있다. As described above, the actual number of tags in the reader recognition area according to the logistics manager's policy is not changed without changing the distribution of tagged logistics in a real situation.

Since may be determined, the height information m _e of the virtual grouping root node can be easily determined.

=4) 이상이라 가정할 때, 가상 집단화 근 노드의 높이 정보 m_e는 2가 되므로, 태그판독기는 처음부터 2비트로 자신의 질문 과정을 시작할 수 있다. For example, the number of end tags that can be included in the tag recognition area of one tag reader is at least four (

= 4) Since the height information m _e of the virtual grouping root node becomes 2, the tag reader can start its own query process with 2 bits from the beginning.

We want to recognize eight tags whose IDs are 00000, 00011, 00111, 01100, 10010, 10100, 11010 and 11111, respectively. Assuming that the number of tags (ke) included in the tag reader area of the tag reader is less than four, the height information m _e of the virtual grouping root node becomes 2, so the tag reader starts its question process with 2 bits from the beginning. To start.

The question starts with two bits, so up to four virtual grouping root nodes. The first virtual grouping root node 00 will cover three tags whose IDs are 00000, 00011 and 00111, respectively. The commonality of the three tags that the first virtual grouping root node 00 covers is that the first two bits are all 00.

The second virtual grouping root node 01 covers tags with ID 01100, the third virtual grouping root node 10 covers tags with ID 10010 and 10100, and finally the fourth virtual grouping root node 11 ) Covers tags with IDs 11010 and 11111. As mentioned above, the virtual grouping root nodes 00, 01, 10, 11 each represent the state of the first bit (s) of the ID, respectively.

을 4라고 가정하고 각각의 가상 집단화 근 노드에 2개의 비트를 할당하면 된다는 것을 알 수 있다. 여기서 높이 정보(m_e) 또는 깊이 정보(m_e)를 대신하는 2개의 비트(00, 01, 10, 11)는, 상술한 바와 같이 태그를 찾아가는 단계 별로 그 값이 변하므로 높이 또는 깊이라는 용어를 사용한 것이다. As described above, referring to Fig. 4, in order to be able to easily recognize all eight tags,

We can assume that is 4 and assign 2 bits to each virtual grouping root node. Here, the two bits (00, 01, 10, and 11) replacing the height information (m _e ) or the depth information (m _e ) have a term of height or depth because their values change according to steps of searching for a tag as described above. Is used.

Hereinafter, a multi-tag recognition method using a virtual grouping root node in radio frequency identification according to the present invention will be described.

5 illustrates a multi-tag recognition method using a virtual grouping root node and a dynamic tag response function according to the present invention.

Referring to FIG. 5, for convenience of description, a process of recognizing six terminal tags having IDs of 00001, 00011, 00111, 01111, 10011, and 11110 will be taken as an example. Assuming that the number ke is 4, the depth information m _e of the virtual clustering root node becomes 2. That is, the tag reader starts the question process with 2 bits from the beginning.

-First step (①)

First, the tag reader sends the reader data frame SON00E to six tags in the tag recognition area. In the reader data frame S0N00E, S denotes S-NULL, 0 denotes a pointer position, N denotes N-NULL, 00 denotes a question bit and E denotes E-NULL. Interpreting reader dataframe S0N00E means that only tags whose first two digits of each tag ID stored in the memory area corresponding to pointer 0 are 00 will respond.

-Second stage (②)

All tags that the reader data frame has received SON00E first change state from standby mode S1 to receive mode S2.

The three tags 01111, 10011, and 11110 whose first two digits of the ID are not 00 are converted to the standby mode S1 state again in the reception mode S2 and do not respond.

On the other hand, the three tags (00001, 00011, 00111) whose first two digits are 00 transmit the tag data frame (b) while changing the state of the tag from the reception mode S2 to the transmission mode S3. The tag data frame (b) transmitted at this time is 0, 0, and 1, which are the third bits of three tags (00001, 00011, 00111). At this point, the pointers of all three tags change from 0 to 10. The pointer changes from 0 (00) to 2 (2) as many as two steps since the first two bits were searched and the third bit must be searched next.

-3rd and 4th stages (③, ④)

Since the third bit values (0, 1) are transmitted from three corresponding tags (00001, 00011, 00111) at the same time, the tag reader determines that a collision has occurred between the tags, and thus the location of the collision, that is, the value of the current pointer. (10) is stored and stored once, and the reader data frame containing the stop signal STOP is transmitted to the tag. The three tags (00001, 00011, 00111) that have received the reader data frame (B) containing the STOP signal change their status back to standby mode S1 and no longer transmit the remaining values. The new reader data frame transmits S10N0E. The new reader data frame S10N0E contains information that only a tag with a pointer of 10, i.e., the value of the third bit of the ID is 0, should be answered.

-Stage 5 (⑤)

The two tags (00001 and 00011) matching the condition contained in the new reader data frame (S10N0E) transmit the next digit, i.e., the fourth bit value, 0 and 1, respectively, while transitioning to the transmission mode S3. At this time, the pointer's value changes to 11 with 1 increased. Since only one bit is compared, the pointer should also be 11, one step from 10. The tag 00111 which does not match the condition contained in the new reader data frame S10N0E changes the state back to the standby mode S1.

-6th and 7th stages (⑥, ⑦)

Since the fourth bits 0 and 1, respectively, are transmitted from two tags (00001 and 00011) at the same time, the tag reader determines that a collision has occurred and stores and stores the collision position, pointer 11, and tags the stop signal STOP. After transmission, the new reader data frame sends S11N0E to find the tag with the value 0 for the position of pointer 11, that is, the fourth bit of the tag ID.

8th Step (⑧)

The two tags (00001 and 00011) receiving the stop signal STOP change their status back to the standby mode S1. The tag (00001) corresponding to the information contained in the newly received reader data frame, i.e., the fourth bit of the ID is 0 is changed to the transmission mode S3, and the last value, i.e., the fifth bit, 1 is transmitted to the tag reader. The state is then changed to inactive mode S4. This completes the recognition of the tag with the ID 00001. However, the tag (00011) that does not match the information contained in the newly received reader data frame maintains the standby state S1.

9th Step (⑨)

The reader data frame transmitted from the tag reader is S11N0E. When searching for a tag whose value of the 4th bit is 0, a collision has already occurred, and the tag whose value of the 4th bit is 0 is searched where the collision occurred. Since the corresponding tag is recognized, the starting point for searching for a new tag is pointer 11, which is the most recent collision position. At this time, since the fourth bit is searched for 0, the search for the fourth bit is now 1, so the reader data frame transmitted from the tag reader to the tag will be S11N1E.

Therefore, in order to find the next tag, the tag reader transmits a new reader data frame S11N1E to change the state of the remaining tags (00011) except the tag (00001) in the current inactive mode S4 state to the receive mode S2. Here, only one tag (00011) corresponds to this for convenience of description, but in practice, multiple tags may correspond to this.

10th Step

Only the tag with the ID of tag 00011 that satisfies the condition contained in the new reader data frame S11N1E changes state to transmission mode S3, and all other tags return to standby mode S1 again. The tag (00011) whose state is switched to the transmission mode S3 transmits the next value, i.e., the fifth bit, 1 to the tag reader and changes the state to the inactive mode S4. As a result, the tag reader also completes the recognition of the ID 00011 tag.

11th Step

To find the next tag, the tag reader starts searching for a new tag at the last crash point 10. Since the previous search at the collision point 10 is for the case where the bit at the pointer 10 is 0, a new search should be performed for the case where the bit at the pointer 10 is 1.

Therefore, a new reader data frame transmits S10N1E to change the state of the remaining four tags whose reception is not completed to the receive mode S2.

-12th and 13th stage (⑫, ⑬)

Only the tag that satisfies the condition included in the new reader data frame S10N1E, i.e., the condition that the third bit of the ID is 1, changes state to the transmission mode S3 and transmits the next value of 1, and then moves the pointer to 11 positions. Go to. There is only one tag that sends a tag dataframe to the tag reader, so there is no conflict between the tags. Therefore, the tag with ID 00111 continuously transmits the last value of 1, and then changes state to inactive mode S4. The remaining three tags all transition back to standby mode S1. This completes the recognition of the tag whose ID is 00111.

This concludes the identification of tags from which the first two bits of the ID are 00, i.e., the first virtual grouping root node (00), followed by the first two bits of the ID is 01, the second virtual grouping root node (01). Searching for tags derived from) begins.

Step 14 (단계)

To find tags whose first two bits start with 01, the tag reader sends a new reader data frame (S0N01E). New Reader Data Frame (A) S0N01E contains information that only the tag whose first two digits of the ID is 01 will respond.

Hereinafter, the numbers 16 to 19 among the numbers enclosed by circles are described as raw numbers 16 to 19.

-15th, 16th and 17th steps (⑮, 16, 17)

The tag 01111 that satisfies the condition included in the new reader data frame S0N01E, that is, the value of the first two digits of the ID is 01, changes its state to the transmission mode S3 and transmits the next value, 1, the third bit. Move the value of the pointer from 0 to 10, in two steps. Since there is no collision between the tags, the tag 01111 continuously increases the pointer by one and transmits the remaining bit values one by one. After all bits are transmitted, the state is changed to inactive mode S4, thereby completing the recognition of the tag with ID 01111.

By going through the 17th step (the original number 17) above, the tag reader completes the search of all the tags whose first two bits are 01, that is, derived from the second virtual grouping root node (01). The second two bits start the search of tags derived from 10, ie, the third virtual grouping root node 10.

-18th stage (18 numbers)

To find tags whose first two bits start with 10, the tag reader sends a new reader data frame, S0N10E. The tag with ID 10011 starts responding to the reader data frame S0N10E sent by the tag reader, and since no collision occurs, it transmits values 0, 1 and 1 continuously and finally changes to inactive mode S4. This completes the recognition of the tag with ID 10011.

By going through the eighteenth step (the original number 18), the tag reader completes the search of the tags derived from the first two bits 10, that is, the third virtual grouping root node 10, and the first two bits 11 resumes the search for tags derived from the fourth virtual grouping root node 11.

19th Step (Raw Number 19)

The tag reader sends a new reader data frame S0N11E to find tags whose first two digits of the ID are 11. The tag with ID 11110 starts a response to S0N11E, sends the 1, 1 and 0 values in succession and then changes state to inactive mode S4.

By going through the nineteenth step (the original number 19), the tag reader completes the searching of tags derived from the first two bits 11, that is, the fourth virtual grouping root node 11, and the tag recognition area of the tag reader. This completes the recognition of all tags included in.

The above 19 stages can be distinguished into two stages (the first terminal tag recognition step and the remaining terminal tag recognition step). Since the tags were first recognized among the tags included in the tag reading area of the tag reader during the steps ① through ⑧, the first terminal tag recognition step is grouped into eight and the remaining terminal tags are recognized. It is defined as a terminal tag recognition step.

While the collision location generated during the initial terminal tag recognition step is identified and stored, the collision location is not used to search and recognize the terminal tag, whereas the other terminal tag recognition step is a collision stored in the initial terminal tag recognition step. Not only the location but also the newly generated collision location during the remaining terminal tag recognition step are distinguished from each other in that it is used.

In the description of FIG. 5, the new collision location that may be newly generated is not mentioned, but this is because the ID of the terminal tag is simply displayed for convenience of description, but it does not mean that such a situation may not occur. For example, in the case of searching for a terminal tag after the second time, when starting a new search at a stored collision position, there is a high probability that at least two tags simultaneously transmit a tag data frame to the corresponding tag reader. Even when a collision occurs while searching for a new tag, the same process as that of handling a collision that occurred when searching for the first tag may be applied.

It will be apparent to those skilled in the art that the system will be designed and operated in consideration of the above-described contents, and thus the above description is unclear and cannot be easily carried out even if such details have not been described in detail.

In the above description, the technical idea of the present invention has been described with the accompanying drawings, which illustrate exemplary embodiments of the present invention by way of example and do not limit the present invention. In addition, it is obvious that any person having ordinary knowledge in the technical field to which the present invention belongs can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

1 illustrates a data frame exchanged between a tag reader and a tag.

2 is a block diagram of a pointer constituting the inside of a tag.

3 shows a state diagram of a tag during communication between the tag reader and the tag.

4 illustrates a tag search tree structure according to an embodiment of the present invention.

5 illustrates a multi-tag recognition method using a virtual grouping root node and a dynamic tag response function according to the present invention.

Claims (8)

1≤

Example of states that satisfy ≤ k ≤ 2 ⁿ

(

Is an integer), and each

Distinguishable by four bits

Defining three virtual grouping root nodes; And Tag reader reminded

Sequentially selecting the virtual grouping root nodes, and recognizing a plurality of terminal tag nodes derived from each virtual grouping root node by using a dynamic response function assigned to a tag, n (n is an integer) is the number of bits of the unique ID of the tag stored in the tag, k (k is an integer) is the number of actual tags in the tag reader recognition area, multi-tag recognition method. The method of claim 1, wherein the recognizing the plurality of terminal tag nodes comprises: In searching for a plurality of terminal tag nodes generated from each of the sequentially selected virtual grouping root nodes, The first terminal tag is searched using the reader data frame and the tag data frame transmitted and received between the tag reader and the tag, and at least one collision position between the tag data frames transmitted from the at least one tag to the tag reader. First terminal tag search step of storing; And After recognizing the first terminal tag through the first terminal tag search step, the at least one collision position, a reader data frame transmitted and received between the tag reader and the tag, a tag data frame and at least one collision position newly generated The remaining terminal tag search step for searching for the remaining terminal tag using the; And wherein the collision location is constant information included in a reader data frame when simultaneously transmitting tag data frames from at least two tags to the tag reader. The method of claim 2, wherein the reader data frame, A pointer specifying a position of at least one bit assigned to a corresponding tag ID for which the tag reader wants a response; A question bit defining a value of a bit corresponding to the pointer, And the collision position is a value of a pointer at the time of the collision. The method of claim 3, wherein the reader data frame, A start signal notifying the tag reader that the data transmission has started; A neutral signal for distinguishing the pointer and the question bit; And And the tag reader further comprises an end signal for notifying the tag that the transmission of the data is complete. The method of claim 2, wherein the reader data frame, When the tag reader recognizes that a collision between the tag data frames is simultaneously transmitted to the tag reader, the tags further include a stop signal indicating that no further tag data frames are transmitted. Multi tag recognition method. The method of claim 3, wherein the tag data frame, And a response bit determined in response to the pointer and the question bit, wherein the response bit is the next bit value of the position of the bit of the tag ID indicated by the pointer. The method of claim 6, wherein the first terminal tag search step, The tag reader transmitting a reader data frame to the tag; A tag data frame transmitting step of transmitting the tag data frame corresponding to the tag to the tag reader; The tag reader stores the newly generated collision position and transmits a collision position storing and stop signal transmitting a stop signal to the tags indicating that the tag no longer transmits a tag data frame; A tag data frame continuous transmission step of continuously transmitting the tag data frame including the data bits assigned to the tag ID to the tag reader until the stop signal is received; Stopping transmitting the tag data frame in which the tags do not transmit the tag data frame when the stop signal is received; And And a first terminal tag recognition step of ending searching and recognition of the corresponding tag after transmitting all data bits assigned to the ID of the corresponding tag. The method of claim 6, wherein the remaining terminal tag search step, A first reader data frame transmitting step of transmitting a second reader data frame including information indicating to search for a next terminal tag from the last collision position stored in the first terminal tag searching step; A second reader data frame including information indicating to search for a next terminal tag in a sequence of collision positions defined first from collision positions defined before the last collision position after searching for a new tag at the last collision position; Transmitting a second reader data frame; The tag is a tag data frame transmission step of receiving the first reader data frame and the second reader data frame and transmits a tag data frame corresponding to the tag reader; The tag reader stores the new collision position when a collision occurs between the tag data frames transmitted from the tag to the tag reader in the above step, and the tag no longer transmits the tag data frame. A new collision position storage and stop signal transmission step of transmitting a stop signal indicating to the tags; A tag data frame continuous transmission step of continuously transmitting the tag data frame including the data bits assigned to the tag ID to the tag reader until the stop signal is received; Stopping transmitting the tag data frame in which the tags do not transmit the tag data frame when the stop signal is received; And And a first terminal tag recognition step of ending searching and recognition of the corresponding tag after transmitting all data bits assigned to the ID of the corresponding tag.

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