KR101521262B1 - RFID tag, RFID tag reader, RFID tag identification system including thereof and providing method thererof - Google Patents

Abstract

The present invention discloses an RFID tag, an RFID tag reader, an RFID tag identification system including the same, and a providing method thereof. According to an embodiment of the present invention, an RFID tag capable of rapidly identifying an RFID tag by using an M-ary query tree, collision information of a tag ID, and a prediction technique, an RFID tag reader, an RFID tag identification system including the same, and a providing method thereof are provided. The RFID tag reader comprises an initialization module, an end module, a setting module, a question transmitting module, a response receiving module, a collision bit determining module, an identification module, a collision processing module, and a control module.

Description

[0001] The present invention relates to an RFID tag, an RFID tag reader, a RFID tag recognition system including the RFID tag,

The present invention relates to an RFID tag, an RFID tag reader, and an RFID tag recognition system including the RFID tag, and more particularly, to an M-ary query tree (M is m ² , m is 2 or more The present invention relates to an RFID tag, an RFID tag reader, a RFID tag recognition system including the RFID tag, and a method of providing the RFID tag.

The present invention is derived from a research carried out as part of a basic research project supported by the Korea Research Foundation in 2012. [Task Number: 2012R1A1A1042703, Title: A stateless framework providing QoS guarantee in cognitive radio networks (Stateless Framework to Provide Guaranteed QoS in Cognitive Radio Networks).

RFID (Radio Frequency Identification) is a technology that reads information embedded in an IC chip in a non-contact manner using radio frequency, and is a technology capable of automatically identifying an object. In general, information is stored in an RFID tag composed of an antenna and a chip, attached to an application object, and then recognized through an RFID reader corresponding to the reader. Unlike the barcode system, the RFID system provides wireless multi-recognition technology, so it has the advantage of recognizing multiple tags in a short time.

In order to apply such RFID technology to the whole industry, it is necessary to solve problems such as low price, low power, miniaturization, security problem and multi tag identification problem of the tag. In the collision problem, when a reader transmits a query to read several pieces of tag information, a plurality of tags receiving the query simultaneously respond to each other, causing a collision between the waves. Since collision problems that can occur when multiple tags are identified have a great influence on the recognition efficiency and speed of tags, an efficient anti-collision algorithm that can solve the collision problems that may occur when identifying multiple tags is essential Is required.

Generally, a reader recognizes a tag as follows.

When a reader queries a plurality of tags, it transmits a radio wave in a broadcast manner, which is called a forward link. This query can only listen to tags within the reader's propagation range, and only those tags within the reader's propagation range will respond. This is called a return link. At this time, since the tags are designed to respond to the inquiry of the reader, there arises a problem that a collision occurs between the radio waves due to the simultaneous response. Since such a collision greatly affects the recognition rate of the RFID system, effective tag collision adjustment process is required.

The collision avoidance algorithm is largely divided into aloha based and tree based.

Aloha based method divides time into slots and responds to only one tag in one slot, making the reader recognize without any tag collision. However, since this approach is based on the uncertainty of probability, in the worst case, the reader may not be able to recognize all the tags in the identification area.

On the other hand, the tree-based method uses a unique tag ID, which is a feature of the RFID tag, to construct a tree and proceed with the tag recognition process. A typical tree-based method is the query tree method. The query tree method ensures that all tags within the transmission range of the reader are recognized.

In the query tree approach, the reader retrieves the prefix of the bit string from the query-queue and queries the tags. The tag that received this query responds to the reader with its ID if the prefix matches the beginning of its tag ID. If two or more tags respond and a collision occurs, the reader adds '0' bit and '1' bit to the query prefix to generate two queries and places them in the query queue. The leader again retrieves the prefix from the query-queue and repeats the query-response process. This process continues until there is no more prefix in the query-queue. Initially, the query-queue is initialized with a null string (ε), and the tags that received ε respond to the reader by their ID without prefix comparison.

Table 1 below shows the process of identifying Tag1 (Tag ID: 0010), Tag2 (Tag ID: 1101), Tag3 (Tag ID: 0011), Tag4 (Tag ID: 0101), Tag5 (Tag ID: 1010).

Query-response phase Query string Query - the state of the queue - {ε} One ε {0, 1} 2 0 {1, 00, 01} 3 One {00, 01, 10, 11} 4 00 {01, 10, 11, 000, 001} 5 01 {10, 11, 000, 001} 6 10 {11, 000, 001} 7 11 {000, 001} 8 000 {001} 9 001 {0010, 0011} 10 0010 {0011} 11 0011 {}

The tag identification process can be expressed in the form of a query tree as shown in FIG. Hereinafter, the tag identification process according to Table 1 will be described with reference to FIG. In FIG. 1, each of the nodes constituting the query tree represents a query-response process, and a query string is displayed on an edge that enters each node. Each node is classified into a collision node, an identification node, and an idle node according to the result of a query-response. The collision node indicates when one or more tags have responded to the query of the reader, and the confirmation node indicates that when only one tag responds, the idle node does not respond to any tag. The numbers in the node represent the order of the query-response. If there are identical tags within the transmission range of the reader, the tag identification process always has the same shape tree.

As shown in Table 1 above, the query-queue is initialized to a null string epsilon. In the first query-response phase, the leader extracts the bit-string (ε) from the query-queue and broadcasts it to the surrounding tags. Then, all the tags (i.e., Tag1 to Tag5) respond to the reader, so that a collision occurs. Then, the leader adds bit '0' and bit '1' to bit string epsilon included in the first query to generate query string '0' and query string '1' and inserts it into the query queue. Thus, the state of the query-queue is {0, 1}.

In the second query-response phase, the leader extracts the bit string '0' from the query-queue and queries the surrounding tags. Then, a collision occurs because Tag1 (tag ID: 0 010), Tag3 (tag ID: 0 011), and Tag4 (tag ID: 0 101) having a tag ID starting with bit '0' are responded. Then, the leader adds bit '0' and bit '1' to the bit string ('0') included in the second query to generate query string '00' and query string '01' and inserts it into the query queue . Thus, the state of the query-queue is {1, 00, 01}.

In the third query-response phase, the leader extracts the bit string '1' from the query-queue and queries the surrounding tags. Then, Tag2 having the tag ID beginning with bit "1" (tag ID: 1 101), Tag5 (tag ID: 1 010), so the response to a crash occurs. Then, the leader adds bit '0' and bit '1' to the bit string ('1') included in the third query to generate query string '10' and query string '11' and inserts it into the query queue . Thus, the state of the query-queue is {00, 01, 10, 11}.

In the fourth query-response phase, the leader extracts the bit string '00' from the query-queue and queries the surrounding tags. Then, Tag1 having the tag ID beginning with bit "00" (tag ID: 00 10), Tag3 (tag ID: 00 11), so the response to a crash occurs. Then, the leader adds bit '0' and bit '1' to the bit string ('00') included in the fourth query to generate query string '000' and query string '001' and inserts it into the query queue . Thus, the state of the query-queue is {01, 10, 11, 000, 001}.

In the fifth query-response phase, the leader extracts the bit string '01' from the query-queue and queries the surrounding tags. Then, only the tag 4 (tag ID: 0101) having the tag ID starting with the bit '01' responds, so that the reader can identify Tag4.

On the other hand, in the eighth query-response step, the leader extracts the query string '000' from the query queue and queries the surrounding tags. However, since there is no tag having a tag ID starting with the query string '000', this query-response step can be classified as an idle node.

In this way, the reader and the tag will repeat the query-response until there is no more query string in the query-queue.

Although the above-described query tree method ensures identification of all the tags existing in the transmission range of the reader, only one bit can be identified at a time, and when the response message collides, information of the collided tags can not be confirmed An idle node, which is an unnecessary query-response process, is added. When there are many tags having similar tag IDs, many collisions occur and the tree is deepened, so that it takes a long time to identify all the tags.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the recognition process of a conventional tree-based method in which unnecessary query-response is generated too much when tags are identified in an environment where tags having similar tag IDs are collected, An RFID tag reader, and an RFID tag recognition system including the multi-bit recognition, the collision information between the tag IDs, and the prediction method, so that the RFID tag can be recognized quickly.

According to an aspect of the present invention, there is provided an RFID tag recognition system using an M-ary query tree (where M is m ² and m is an integer of 2 or more) Wherein the RFID tag comprises: receiving a query bit string broadcasted by the RFID tag reader; when the query bit string matches a prefix of a tag ID of the RFID, ] Transforms the subsequent m-bit string of the prefix among the tag IDs of the RFID into an M-bit conversion code, converts the converted M-bit conversion code, and the tag ID of the RFID and the subsequent m Generating a response including bits other than the bit string, and transmitting the generated response to the RFID tag reader, wherein the RFID tag reader comprises: (a) Adding a null bit string to a predetermined data structure capable of storing a string, (b) ending tag recognition if the data structure is empty, (c) if the data structure is not empty, (A) extracting a bit string from the data structure and setting the extracted bit string as a query bit string, (b) broadcasting the set query bit string, (e) Receiving a response transmitted from at least a portion of one RFID tag; (f) determining a collision bit occurring in the response; (g) if the collision bit is not generated in the response, (H) performing a collision processing step when a collision bit is generated in the response, and (i) (H-1) if the collision bit is present in the M-bit conversion code among the bit strings included in the response, performing the collision processing step (h) An M-bit collision code corresponding to each collision bit in the M-bit conversion code is calculated by the following equation (2), and each of the calculated M-bit collision codes is represented by the following equation (H-2) adding the generated query bit string to the data structure; and (h-2) adding the generated query bit string to the data structure by combining the query bit string and the collision string of each m- If the bit does not exist in the M-bit conversion code, the M-bit conversion code is inversely transformed into an m-bit inverse transformed string by the following equation (1) And generating a subsequent query bit string including the converted m-bit inverted string and adding the generated subsequent query bit string to the data structure. / RTI >

[Equation 1]

(Where S is an m bit string, C is an M-bit conversion code (where M = 2 ^m ), and dec (S) is a value obtained by converting S into a decimal number)

[Equation 2]

Where b is the collision bit, P is the transform code of M bits, pos (P, b) is the position of the collision bit b in the transform code P of M bits, C is the collision bit of M bits corresponding to the collision bit b, Code)

In one embodiment, the step (h-2) may further comprise the step of, when the number of bits from immediately next bit of the M-bit conversion code to immediately before the first collision bit among the bit strings included in the response is mxk ( Where k is an integer equal to or greater than 1 and equal to or less than m x (k + 1) -1, the query bit string, the inverse transformed m-bit inverse transformed string, Lt; RTI ID = 0.0 > mxk < / RTI >

In one embodiment, the step (h-2) may further include a step of, when the number of bits from immediately next bit of the M-bit conversion code to immediately before the first collision bit among the bit strings included in the response is mxk + 1 (K + 1) or less of the bit string included in the response and the inverse transformed string of the inverse m transformed bit string, (M + k) th bit to (m + m) th (k + 1) th bit among the bit strings included in the response, And combining the bit strings constituted by substituting bits '0' and bit '1' into the respective collision bits included in the additional string in the additional string, respectively, to generate a subsequent query bit string.

In one embodiment, the collision processing step may be configured so that, when the length of the bit string included in the response is M or less, an M-bit collision code corresponding to each collision bit in the M- And calculates a collision string of m bits corresponding to each of the calculated collision codes of M bits according to the equation 1 and combines the collision string of each of the calculated m bits with the query bit string, Further comprising the steps of: calculating a tag ID of each RFID tag that has transmitted the response, and recognizing each RFID tag that transmitted the response through the calculated tag ID, If the length of the string is M or less, the steps (h-1) and (h-2) may not be performed.

According to another aspect of the present invention, there is provided an RFID tag using an M-th order query tree (where M is m ² and m is an integer of 2 or more), wherein the RFID tag includes a query reception Module converts a subsequent m-bit string of the RFID tag ID of the RFID into an M-bit conversion code when the query bit string matches the prefix of the tag ID of the RFID, A response generation module for generating a response including the M-bit conversion code and the remaining m-bit string of the RFID tag ID and the subsequent m-bit string of the prefix, and a response generation module for generating the response to the RFID tag reader And a response transmission module for transmitting the RFID tag.

According to another aspect of the present invention, there is provided an RFID tag reader using an M-th order query tree (where M is m ² and m is an integer of 2 or more) An end module for performing an end step of ending tag recognition when the data structure is empty; a bit string extracting part for extracting a bit string from the data structure when the data structure is not empty; A setting module for setting a string as a query bit string, a query transmission module for performing a query transmission step of broadcasting the set query bit string set therein, and at least one of the at least one RFID tag receiving the query bit string A response reception module for performing a response reception step of receiving a response transmitted from the part, A collision bit determination module for performing a collision bit determination step of determining a collision bit, a recognition module for recognizing an RFID tag that transmitted the response based on the response when a collision bit is not generated in the response, A collision processing module for performing a collision processing step when the collision bit occurs, and a collision processing module for colliding the end module, the setting module, the inquiry transmission module, the response reception module, the collision bit determination module, And a control module for controlling to repeatedly execute the end step, the setting step, the query transmission step, the response reception step, the collision bit determination step, the recognition step, and the collision processing step, , And in order to perform the collision processing step, the collision bit is included in the M-bit transform code of the bit string included in the response If there is an M-bit collision code corresponding to each collision bit in the M-bit conversion code by the above-mentioned [Expression 2], and calculates each of the calculated M-bit collision codes by m A first subsequent query to combine the query bit string and each of the m-bit collision strings inverted to produce a subsequent query bit string, and to add the generated subsequent query bit string to the data structure And if the collision bit does not exist in the M-bit conversion code, inversely transforms the M-bit conversion code into an m-bit inverse transformed string according to [Expression 1], and outputs the query bit string and the inverse- generating a subsequent query bit string including an m-bit inverted string, and adding the generated subsequent query bit string to the data structure 2 is the RFID tag reader is provided comprising a subsequent query generation module.

In one embodiment, the second succeeding query generation module may be configured so that the number of bits from immediately next bit of the M-bit conversion code to immediately before the first collision bit among the bit strings included in the response is mxk ( Where k is an integer equal to or greater than 1 and equal to or less than m x (k + 1) -1, the query bit string, the inverse transformed m-bit inverse transformed string, Lt; RTI ID = 0.0 > mxk < / RTI >

In one embodiment, the second subsequent query generation module may be configured such that the number of bits from the immediately following bit of the M-bit conversion code to the immediately preceding impulse bit among the bit strings included in the response is mxk + 1 (K + 1) or less of the bit string included in the response and the inverse transformed string of the inverse m transformed bit string, (M + k) th bit to (m + m) th (k + 1) th bit among the bit strings included in the response, It is possible to combine the bit strings constituted by substituting bits '0' and bit '1' into the respective collision bits included in the additional string in the additional string to generate a subsequent query bit string.

In one embodiment, the collision processing module may set the M-bit collision code corresponding to each collision bit in the M-bit conversion code to the [Equation 2] if the length of the bit string included in the response is M or less And calculates a collision string of m bits corresponding to each of the calculated collision codes of M bits according to the equation 1 and combines the collision string of each of the calculated m bits with the query bit string, And a prediction module that recognizes each RFID tag that transmits the response through the calculated n tag IDs.

According to another aspect of the present invention, there is provided an RFID tag providing method using an M-th order query tree (where M is m ² and m is an integer of 2 or more), wherein the RFID tag is broadcasted from a predetermined RFID tag reader The method comprising: receiving a query bit string; if the query bit string matches a prefix of a tag ID of the RFID, receiving a subsequent m bit string of the prefix among the tag ID of the RFID by the [Equation 1] Generating a response including the converted M-bit conversion code and the remaining ones of the tag IDs of the RFID except for the prefix and the subsequent m-bit string of the prefix; and And transmitting the generated response to the RFID tag reader.

According to another aspect of the present invention, there is provided a method of providing an RFID tag reader using an M-th order query tree (where M is m ² and m is an integer of 2 or more), the method comprising the steps of: (a) (B) terminating the tag recognition if the data structure is empty, (c) ending the tag identification if the data structure is empty, (c) Extracting one bit string from the data structure and setting the extracted bit string as a query bit string, broadcasting the query bit string set by the RFID tag reader, (e) receiving a response sent from at least a portion of the at least one RFID tag that received the query bit string; (f) (H) recognizing the RFID tag that transmitted the response based on the response if the collision bit is not generated in the response, (h) if a collision bit has occurred in the response, (I) the RFID tag reader repeatedly performing the steps (b) to (h), wherein the collision processing step comprises: (h-1) The M-bit collision code corresponding to each collision bit in the M-bit conversion code is calculated by the above-mentioned [Expression 2], and if the calculated M-bit collision code is included in the M- In accordance with Equation (1), combines the query bit string with the collision string of each m bit reversed in order to generate n subsequent query bit strings, And (h-2) if the collision bit is not present in the M-bit conversion code, converting the M-bit conversion code into the [1] To an inverse transformed string of m bits and generating a subsequent query bit string including the query bit string and the inverse transformed m inverse transformed string, and adding the generated subsequent query bit string to the data structure A method of providing an RFID tag reader including the RFID tag reader is provided.

According to another aspect of the present invention, there is provided a computer-readable recording medium on which a program for performing the above-described method is recorded.

According to an embodiment of the present invention, by using multi-bit recognition, collision information between tag IDs, prediction techniques, etc., unnecessary query-responses are generated too much when identifying tags in an environment where tags having similar tag IDs are gathered The RFID tag can be recognized quickly as compared with the conventional tree-based method which operates inefficiently.

BRIEF DESCRIPTION OF THE DRAWINGS A brief description of each drawing is provided to more fully understand the drawings recited in the description of the invention.
1 is a diagram for explaining a method of identifying an RFID tag by a conventional query tree method.
2 is a block diagram illustrating a schematic configuration of an RFID tag recognition system according to an embodiment of the present invention.
FIG. 3A is a diagram illustrating an m-bit-M bit conversion table used in an RFID tag recognition system according to an embodiment of the present invention, and FIG. 3B is a diagram illustrating a 2-bit-4 bit conversion table.
4 is a flowchart illustrating a process performed in an RFID tag according to an embodiment of the present invention.
5A to 5C are flowcharts illustrating a process performed by an RFID tag reader according to an exemplary embodiment of the present invention.
6 is a diagram illustrating the configuration of an RFID tag according to an embodiment of the present invention.
FIGS. 7A and 7B are views showing the configuration of an RFID tag reader according to an embodiment of the present invention.
FIG. 8 is a diagram for explaining a series of processes in which an RFID tag reader recognizes a plurality of peripheral tags according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise.

In this specification, the terms "comprises" or "having" and the like refer to the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of features, numbers, steps, operations, components, parts, or combinations thereof.

Also, in this specification, when any one element 'transmits' data to another element, the element may transmit the data directly to the other element, or may be transmitted through at least one other element And may transmit the data to the other component. Conversely, when one element 'directly transmits' data to another element, it means that the data is transmitted to the other element without passing through another element in the element.

Hereinafter, the present invention will be described in detail with reference to the embodiments of the present invention with reference to the accompanying drawings. Like reference symbols in the drawings denote like elements.

2 is a block diagram of an RFID tag recognition system (hereinafter referred to as a " tag recognition system ") using an M-ary query tree (where M is m ² and m is an integer of 2 or more) according to an embodiment of the present invention. (Hereinafter, referred to as " a ").

2, the tag recognition system 10 includes an RFID reader 100 (hereinafter referred to as a reader) and at least one RFID tag 200-1 to 200-n . ≪ / RTI > Each of the tags 200-1 to 200-n may be assigned a unique tag ID, and each tag ID may be in the form of a bit string of a specific length.

The reader 100 can transmit a query to surrounding tags. The reader 100 can transmit a query through radio waves of a broadcasting system. Meanwhile, a predetermined bit string (query bit string) may be included in the query transmitted by the reader 100.

When the tags 200-1 to 200-n are located within the range of the radio wave of the reader 100, the reader 200 can transmit a response corresponding to the received query to the reader 100. [ On the other hand, not all the tags that have received the query from the reader 100 respond to the reader 100, compare the query bit string included in the received query with the tag ID of the reader 100, Part of the query string matches the query string.

Each of the tags 200-1 to 200-1 and the reader 100 is an M-ary query tree according to the technical idea of the present invention, where M is m ² , m is 2 or more Integer) of the RFID tag.

In the RFID tag recognition method using an M-th order query tree according to the technical idea of the present invention, a predetermined conversion function for converting an m-bit string S into an M-bit conversion code C corresponding thereto can be used. The transform function may be of the form [Equation 1].

[Equation 1]

(S is an m-bit string, C is an M-bit conversion code corresponding to S, and dec (S) is a value obtained by converting S to decimal)

The conversion relation according to the above [Expression 1] can be represented by a predetermined conversion table.

Fig. 3A shows a generalized conversion table, and Fig. 3B shows a conversion table when m is 2. 3A and 3B, when converting the string S of m bits into the conversion code C of M bits through the above-mentioned [Expression 1], C (dec (S)) + And the remaining bits of C are all " 0 ".

On the other hand, it will be easily understood by those skilled in the art that the M-bit transform code can be inversely transformed into the m-bit bit string corresponding to Equation (1).

FIG. 4 is a flowchart illustrating a process performed by the tags 200-1 through 200-n.

Referring to FIG. 4, the tag 200 can wait for reception of a query broadcasted by the reader 100 (S100). When the reader broadcasts a query, the tag 200 receives the bit string included in the query (S110).

The tag 200 determines whether the received query bit string matches the prefix of its tag ID (that is, the part before the tag ID) (S120). If the query bit string does not coincide with the prefix, .

If the received query bit string matches the prefix of its tag ID, the tag 200 converts the subsequent m-bit string of the prefix among its tag IDs into an M-bit conversion code according to [Equation 1] (S130). For example, if m is 2, the tag 200 is a tag ID is "00 10 01 11 ', and the query bit string is" 00 "if the tag 200 is a prefix of" 00 "of the next 2 Quot; 10 " can be converted into the conversion code '0100'.

In addition, the tag 200 may generate a response including the converted M-bit conversion code and bits other than the m-bit string of the prefix and the subsequent m-bit string of the tag ID at step S140. In the above example, the transform code of the converted M-bit is "0100", the tag ID ( "00 10 01 11 ') of the prefix (' 00 ') and a subsequent m-bit string (' 10 ') of the prefix The bit string '0100 01 10' may be included in the response generated by the tag since the remaining bits are '01 10'.

The tag 200 may transmit the generated response to the reader 100 (S150).

FIGS. 5A through 5C are flowcharts for explaining a process performed by the reader 100. FIG.

Referring to FIG. 5A, when the reader 100 starts to recognize a tag, the tag 100 may add a null string? To a predetermined data structure capable of storing a bit string (S200, S210 ).

The data structure may be, for example, a stack or a queue. Hereinafter, an example in which the data structure is implemented as a queue will be described, but it will be easily understood by those skilled in the art that the following description can be applied to various known data structures in the same way .

Meanwhile, the reader 100 may determine whether the query-queue Q is empty (S220). If the query-queue Q is empty, the reader 100 may terminate the tag recognition process (S230).

If the query-queue Q is not empty, the reader 100 extracts a bit string from the query-queue Q and sets it as a query bit string S (S240). If one bit string is extracted from the query-queue, the extracted bit string is removed from the query-queue, which may be true for other data structures as well.

Meanwhile, the reader 100 may broadcast the query bit string S (S250). If the neighbor tags (for example, 200-1 through 200-n) receive the query bit string S, (S260). ≪ / RTI > As described above with reference to FIG. 4, only the tag whose query bit string S matches the prefix of its tag ID can respond to the query.

The reader 100 may determine a collision bit generated in the received response (S270).

When two or more tags respond to the query of the reader 100, since each tag ID of each tag has a unique value, a bit string at a specific position among the bit strings included in each response has a value of 0 or 1 In which case the bit at the particular location may be a collision bit. In other words, if the bit at a specific position in the bit string included in the response of each tag to the query of the reader 100 is not '0' bit or '1' bit, .

For example, when three tags respond to the query of the reader 100 as '0 01 01 0 ', '0 10 01 0 ', and '0 01 01 1 ', bits 2 and 3 , And the sixth bit. If the collision bit is represented by?, The reader 100 can determine '0 ?? 01?', Which is the response information including the collision bit, from the response of each tag in the above example.

On the other hand, if there is only one tag that responds to the inquiry, the collision bit is not generated. Therefore, if the collision bit is not generated in the response, the reader 100 generates the RFID tag (S290), and repeats the above-described process from step S220.

If a collision bit is generated in the response, the reader 100 may perform the collision processing step as described later (S300), and then repeat the above-described processes from step S220.

5B is a flowchart illustrating a conflict processing step S300 according to an embodiment of the present invention.

In one embodiment, the reader 100 determines whether the length of the bit string included in the response of the tag to the query is less than or equal to M (S310). If the length is less than or equal to M, the reader 100 may perform a prediction technique S400).

If the length of the bit string included in the response of the tag to the query is greater than M, the reader 100 determines whether the collision bit is present in the M-bit conversion code among the bit strings included in the response (S320).

In one embodiment, the M-bit transform code may be the first M bits of the bit string included in the response of each tag, and in this case, the reader 100 may determine that the collision bit is one of the bit strings Whether or not the collision bit is present in the M-bit transformed code among the bit strings included in the response, depending on whether or not the collision bit is included in the initial M-bit.

If the collision bit is present in the M-bit conversion code among the bit strings included in the response, the reader 100 calculates an M-bit collision code corresponding to each of the collision bits in the M-bit conversion code (S330). The reader 100 can use the following equation (2) to calculate the M-bit collision code corresponding to each collision bit.

[Equation 2]

(b is a collision bit, P is a conversion code of M bits, pos (P, b) is a position of collision bit b in M-bit conversion code P, and C is a collision code of M bits corresponding to collision bit b )

For example, if m is 2 (and thus M = 2 ² = 4) and the reader 100 determines ' 0 ?? 0 1?' As the response information including the collision bit from the response of each tag, Since the collision bit is included in the M-bit conversion code (i.e., the first 4 bits), the reader 100 calculates '0100' as the collision code corresponding to the first collision bit in the M-bit conversion code, It is possible to calculate '0010' as a collision code corresponding to the second collision bit in the M-bit conversion code.

Then, the reader 100 can inversely convert each of the calculated M-bit collision codes into m-bit collision strings by the above-described [Expression 1]. In the above example, the collision string of m bits corresponding to collision code '0010' becomes '01', and the collision string of m bits corresponding to collision code '0100' becomes '10'.

Then, the reader 100 combines the query bit string S and each of the collision strings of m bits inverted to generate a subsequent query bit string corresponding to each collision string (S350), and generates a subsequent query bit A string may be added to the query-queue Q (S360). In the above example, if the query string was' 00 ', the reader 100 combines the query string' 00 'with the m-bit collision string' 01 'to generate a subsequent query bit string' 0001 'and add it to the query-queue Q and also combine the m-bit collision string' 10 'with the query string' 00 'to generate a subsequent query bit string' 0010 'corresponding to the collision string' 10 ' 'And add it to the query-queue (Q). As such, the subsequent query bit string added to the query-queue Q may be equal to the number of collision bits in the M-bit translation code.

On the other hand, if it is determined in step S320 that the collision bit does not exist in the M-bit conversion code among the bit strings included in the response, the reader 100 converts the M-bit conversion code into [Expression 1] To an inverse transformed string of m bits (S370).

The reader 100 then generates a subsequent query bit string including the query bit string and the inverse transformed m-bit inverse transformed string at step S380, and transmits the generated subsequent query bit string to the query queue Q May be added (S390).

On the other hand, in step S380, the method of generating the subsequent query bit string may vary.

In one embodiment, the reader 100 may concatenate the query bit string and the m-bit inverse transform string to produce one subsequent query bit string, but in order to reduce the number of query-responses, Technique.

According to one embodiment of applying the Manchester coding scheme, the reader 100 determines whether the number of bits from immediately next bit of the M-bit conversion code to immediately before the first collision bit among the bit strings included in the response is m x k (K + 1) -1 or less, the inverse transformed string of the inverse m transformed m bit, and the bit string included in the response, The mxk bits located immediately after the M-bit transform code may be combined to generate a subsequent query bit string.

For example, if m is 2 (and thus M = 2 ² = 4) and the reader 100 determines that the response information is '0010 0100 ? 1' from the response of each tag to the query bit string '11' , The collision bit does not exist in the M-bit transform code (i.e., the most preceding position '0010') and the number of bits (' 0100 ') from immediately following bit of the M-bit transform code until just before the first collision bit The reader 100 reads the query bit string '11', the m-bit inverted string '01', and the first bit from the immediately following bit of the M-bit conversion code, Combining the bits (' 0100 ') just prior to the collision bit, it is possible to generate '1101 0100 ' as a subsequent query bit string.

According to another embodiment of applying the Manchester coding scheme, the number of bits from the immediately following bit of the M-bit conversion code to the immediately before the first collision bit among the bit strings included in the response is m x k + 1 , k is an integer equal to or greater than 0, and m (k + 1) or less, the inverse transformed string of the m bits and the bit string included in the response, (K + 1) th to M + m x (k + 1) -th bits among the bit strings included in the response, and an additional string consisting of m + And a bit string formed by substituting bits '0' and bit '1' into each collision bit included in the additional string, respectively, to generate a subsequent query bit string.

For example, m is 2 (thus, M = ² 2 = 4), and that the reader 100 from each of the tags in response to a query bit string "01""0100 1? The collision bit is not present in the M-bit conversion code (i.e., the most preceding '0100'), and the bits from immediately after the M-bit conversion code to immediately before the first collision bit of a bit string included in the '1' count is one (i.e., k = 0), so the reader 100 may query the bit string "01", the inverse transform a string of m bits '10', and the response of ('0110') combining m × k bits immediately after the M-bit conversion code and a bit string ('0110') obtained by combining a bit string ''' (4 + l = 5 second) from the m + m × (k + 1) th (4 + 2 = 6) bits, additional string ( '1?) consisting of up to the sub-strings ( "1?") in combines the bit "0" and bit "1" to the bit string "10" and "11" assigned to each of collision bits included in each of two follow-up query bit string "0110 10 'And' 0110 11 '.

Meanwhile, if the length of the bit string included in the response is equal to or smaller than M, the reader 100 can perform a prediction technique (S400) as described above. Hereinafter, .

Referring to FIG. 5C, the reader 100 may calculate an M-bit collision code corresponding to each collision bit in the M-bit conversion code according to Equation 2 (S410). For example, if the reader 100 determines '? 00?' As the response information from the response of each tag to the query bit string '1100', the reader 100 determines that the first collision '1000', which is a collision code corresponding to a bit, and '0001', which is a collision code corresponding to a second collision bit in an M-bit transformation code.

Thereafter, the reader 100 may calculate the m-bit collision string corresponding to each of the calculated M-bit collision codes by using Equation 1 (S420). In the above example, the reader 100 can calculate the collision string 'm' of 'm' corresponding to the collision code '0001' and the collision string m of m corresponding to the collision code '1000' have.

The tag ID of each tag that transmitted the response may be calculated by combining the query bit string and the calculated collision string of m bits (S430). In the above example, the reader 100 can calculate the tag ID '110000' by combining the query bit string '1100' and the collision string '00', and the query bit string '1100' and the collision string '11' 110011 'can be calculated by combining them.

Each RFID tag that transmitted the response can be recognized through the calculated tag ID (S440). In the above example, the reader 100 can recognize two tags that transmitted a response through the two calculated tag IDs '110000' and '110011'.

By using the above-described prediction technique, the reader 100 can recognize each tag without additional query-response even when a collision of responses by various tags occurs.

FIG. 6 is a diagram illustrating a configuration of a tag 200 according to an embodiment of the present invention, and FIGS. 7A to 7B are diagrams showing a configuration of a reader 100 according to an embodiment of the present invention.

As shown in FIG. 6, the tag 200 may include a query receiving module 210, a response generating module 220, and a response transmitting module 230. 7A, the reader 100 includes an initialization module 110, a termination module 120, a setting module 130, a query transmission module 140, a response reception module 140, A recognition module 160, a recognition module 170, a conflict processing module 180, and a control module 190. 7B, the conflict processing module 180 may include a first subsequent query generation module 181, a second subsequent query generation module 182, and a prediction module 183. According to an embodiment of the present invention, some of the above-described components may not necessarily correspond to the components necessary for the implementation of the present invention, 0.0 > 100 < / RTI > may include more components.

The tag 200 or the reader 100 may include hardware resources and / or software necessary to implement the technical idea of the present invention.

According to an embodiment of the present invention, the initialization module 110, the termination module 120, the setting module 130, the query transmission module 140, the response reception module 140, the collision bit determination module 160, ), The conflict processing module 180, and the control module 190 are also located in different physical devices, and the configurations located in different physical devices are organically coupled to each other to realize functions performed by the respective modules have.

In this specification, a module may mean a functional and structural combination of hardware for carrying out the technical idea of the present invention and software for driving the hardware. For example, the module may mean a logical unit of a predetermined code and a hardware resource for executing the predetermined code, and it does not necessarily mean a physically connected code or a kind of hardware. Can be easily deduced to the average expert in the field of < / RTI >

Referring to FIG. 6, the query receiving module 210 may receive a query bit string broadcasted by the reader 100.

When the query bit string matches the prefix of the tag ID of the tag 100, the response generation module 210 sets the following m bit string of the tag ID among the tag IDs to M bits Conversion code, and generates a response including the converted M-bit conversion code and the remaining bits of the tag ID of the RFID, except for the prefix and the subsequent m-bit string of the prefix.

The response transmission module 220 may transmit the generated response to the reader 100.

Referring to FIG. 7A, the initialization module 110 may add a null bit string to a predetermined data structure capable of storing a bit string.

The termination module 120 may perform an end step of terminating the tag recognition if the data structure is empty.

If the data structure is not empty, the setting module 130 may perform a setting step of extracting one bit string from the data structure and setting the extracted bit string as a query bit string.

The query transmission module 140 may perform a query transmission step of broadcasting the set query bit string.

The response receiving module 150 may perform a response receiving step of receiving a response transmitted from at least a part of the at least one RFID tag that has received the query bit string.

The collision bit determination module 160 may perform a collision bit determination step of determining a collision bit generated in the response.

If the collision bit is not generated in the response, the recognition module 170 may perform a recognition step of recognizing the RFID tag that transmitted the response based on the response.

The collision processing module 180 may perform a collision processing step when a collision bit is generated in the response.

The control module 190 may control the end module 120, the setting module 130, the query transmission module 140, the response reception module 150, the collision bit determination module 160, 170, and the collision processing module 180 repeatedly execute the end step, the setting step, the query transmission step, the response reception step, the collision bit determination step, the recognition step, and the collision processing step can do.

Referring to FIG. 7B, when the collision bit is present in the M-bit conversion code among the bit strings included in the response, the first subsequent query generation module 181 determines that each collision bit in the M- The corresponding M-bit collision code is calculated by the above-mentioned [Expression 2], each of the calculated M-bit collision codes is inversely transformed into an m-bit collision string by the above-mentioned [Expression 1] Combine the collision strings of each m bits to generate a subsequent query bit string, and add the generated subsequent query bit string to the data structure.

If the collision bit is not present in the M-bit conversion code, the second subsequent query generation module 182 inversely transforms the M-bit conversion code into an m-bit inverse-converted string by the [Expression 1] A subsequent query bit string including the query bit string and the inverse transformed m-bit inverted string may be generated, and the generated subsequent query bit string may be added to the data structure.

In one embodiment, the second subsequent query generation module 182 determines whether the number of bits from immediately next bit of the M-bit conversion code to immediately before the first collision bit in the bit string included in the response is m x k (K + 1) -1 or less, the inverse transformed string of the inverse m transformed m bit, and the bit string included in the response, The mxk bits located immediately after the M-bit transform code may be combined to generate a subsequent query bit string.

In another embodiment, the second subsequent query generation module 182 determines that the number of bits from immediately next bit of the M-bit conversion code to immediately before the first collision bit among the bit strings included in the response is m x the inverse transformed string of m bits and the inverse transformed string of the bit string contained in the response, when k + 1 (where k is an integer of 0 or more) and m (k + 1) (K + 1) th to (M + m) th (k + 1) th bit strings among the bit strings included in the response, Bit string formed by substituting bit '0' and bit '1' into each of the collision bits included in the additional string in the additional string composed of bits, to generate a subsequent query bit string.

Meanwhile, if the length of the bit string included in the response is equal to or less than M, the prediction module 183 calculates an M-bit collision code corresponding to each collision bit in the M-bit conversion code according to Equation (2) And calculates a collision string of m bits corresponding to each of the calculated collision codes of M bits by the above expression 1 and combines the collision string of each of the calculated m bits with the query bit string to transmit the response It is possible to calculate the tag ID of each of the RFID tags and to recognize each RFID tag that transmitted the response through the calculated n tag IDs.

Hereinafter, a series of processes in which the reader 100 recognizes a plurality of peripheral tags according to an embodiment of the present invention will be described with reference to FIG. In the example of FIG. 8, m is 2, and tag 1 (tag ID: 00 01 01), Tag 2 (tag ID: 00 10 11), Tag 3 0110 11), Tag 5 (Tag ID: 11 00 00), and Tag 6 (Tag ID: 11 00 11) exist.

Table 2 below shows the process of identifying each tag existing in the vicinity of the reader 100.

order Query string Query - the state of the queue 0 {ε} One ε {00, 01, 11} 2 00 {01, 11, 0001, 0010} 3 01 {11, 0001, 0010, 011010, 011011} 4 11 {0001, 0010, 011010, 011011, 1100} 5 0001 {0010, 011010, 011011, 1100} 6 0010 {011010, 011011, 1100} 7 011010 {011011, 1100} 8 011011 {1100} 9 1100 {}

The tag identification process may be expressed in the form of a query tree as shown in FIG.

Since the reader 100 can add a null string epsilon to the query-queue when the tag recognition is started (S210), the query-queue is initialized to the null string epsilon as shown in Table 2 above .

In the first query-response step, the reader extracts a bit string? From the query-queue and sets it as a query bit string S240 and broadcasts it to surrounding tags S250. Then, all the tags (i.e., Tag1 to Tag6) respond to the reader. As described above, each tag converts the subsequent m-bit string of the prefix matching the query bit string of its tag ID into an M-bit conversion code (S130), and converts the prefix and the prefix It is possible to respond to a bit string composed of bits other than the following m bit strings (S140, S150). Therefore, the first M bits among the bit strings included in the response of each tag may be M-bit conversion codes. The response of each tag is shown in [Table 3] below.

tag Tag ID The bit string contained in the tag's response. One 00 00 01 0001 01 01 2 00 10 11 0001 10 11 3 01 10 01 0010 10 01 4 01 10 11 0010 10 11 5 11 00 00 1000 00 00 6 11 00 11 1000 00 11

Meanwhile, the reader 100 can determine a collision bit generated in the response of each tag (S270), and the response information including the collision bit determined by the reader 100 is' ? 0 ?? ?? '.

Since the collision has occurred in the response, the reader 100 performs the collision processing step (S280, S300).

Since the collision bit exists in the M-bit conversion code, the reader 100 generates M-bit collision codes '0001', '0010' and '1000' corresponding to each collision bit in the M- (S330). The reader 100 generates a collision string '00' corresponding to the collision code '0001', a collision string '01' corresponding to the collision code '0010', and a collision string '11' corresponding to the collision code '1000' (S350) and add it to the query-queue by combining the query bit string? With each of the generated collision strings to generate subsequent query bit strings' 00 ', 01', '11' (S360). Thus, the state of the query-queue is {00, 01, 11} as shown in [Table 2].

In the second query-response step, the reader extracts a bit string '00' from the query-queue and sets it as a query bit string (S240) and broadcast it to peripheral tags (S250).

Then, the tag ID of a tag starts with a query bit string "00" Tag1 (tag ID: 00 01 01), Tag2 ( tag ID: 00 10 11) are the respective responses of '0010 01' and '0100 11' .

Meanwhile, the reader 100 can determine the collision bit generated in the response of each tag (S270), and the response information including the collision bit determined by the reader 100 becomes ' 0 ?? 0 ? 1' .

Since the collision has occurred in the response, the reader 100 performs the collision processing step (S280, S300).

On the other hand, since the collision bit exists in the M-bit conversion code, the reader 100 can calculate the M-bit collision codes '0010' and '0100' corresponding to each collision bit in the M-bit conversion code (S330). The reader 100 then generates a collision string '01' corresponding to the collision code '0010', a collision string '10' corresponding to the collision code '0100' (S340) (S350) and combine the generated collision strings with each other to add it to the query-queue (S360). Therefore, the state of the query-queue is {01, 11, 0001, 0010} as shown in [Table 2].

In a third query-response step, the leader extracts a bit string '01' from the query-queue and sets it as a query bit string (S240) and broadcast it to surrounding tags (S250).

Then, the tag ID of the tag starting with a query bit string "01" Tag3 (tag ID: 01 10 10) and Tag4 (tag ID: 01 10 11) are the respective responses of '0100 10' and '0100 11' .

Meanwhile, the reader 100 can determine the collision bit generated in the response of each tag (S270), and the response information including the collision bit determined by the reader 100 becomes ' 0010 1?'.

Since the collision has occurred in the response, the reader 100 performs the collision processing step (S280, S300).

Since the collision bit is not present in the M-bit conversion code, the reader 100 can invert the M-bit conversion code ' 0100 ' to m-bit inverse-converted string ' 10 ' (S370).

The reader 100 may then generate a subsequent query bit string including the query bit string '01' and the inverse transformed m-bit inverted string ' 10 ' (S380). Meanwhile, the above-described Manchester coding scheme can be applied in the process of generating a subsequent query bit string. That is, as can be seen from the response information ' 0010 1 ?', If the number of bits ' 1 ' from immediately next bit of the M-bit transform code ' 0100 ' k = 0), the reader 100 generates a query bit string '01', an m-bit inverted string '10', and an m × M + m × k + 1 (4 + 1 = 5) th bit string among the bit strings included in the response and a bit string ('0110' 0 'and bit' 0 'are added to each collision bit included in the additional string (' 1? ') in an appended string (' 1? ') composed of bits from (k + 1) 0110 10 'and' 0110 11 ', respectively, by combining bit strings' 10 ' and ' 11 ', respectively, each of which is substituted with a bit string ' 1 '

The reader 100 may add the generated subsequent query bit strings '0110 10 ' and '0110 11 ' to the query queue (S360) and the state of the query queue is {11 , 0001, 0010, 011010, 011011}.

The fourth query-response step may proceed in the same manner as described above. After the fourth query-response step, the state of the query-queue is {0001, 0010, 011010, 011011, 1100}.

On the other hand, in the fifth inquiry-response step, the reader 100 extracts the bit string '0001' from the query-queue and sets it as a query bit string (S240), and broadcasts it to the surrounding tags (S250).

Then, only Tag1 (tag ID: 00 01 01), which is a tag whose tag ID starts with the query bit string '0001', responds. Therefore, the collision does not occur, and the reader 100 can recognize Tag1 that transmitted the response (S270 to S290). On the other hand, in the fifth query-response step, since the subsequent query bit string is not added, the state of the query-queue becomes {0010, 011010, 011011, 1100} as shown in Table 2.

In the sixth query-response step, Tag2 (tag ID: 001011) starting with '0010' can be identified in the same manner.

In the seventh inquiry-response step, Tag3 (tag ID: 011010) starting with '011010' can be identified in the same manner.

In the eighth inquiry-response step, Tag4 (tag ID: 011011) starting with '011011' can be identified in the above manner. At this time, the state of the query-queue is {1100} as shown in [Table 2].

In the ninth query-response step, the reader 100 extracts a bit string '1100' from the query-queue and sets it as a query bit string (S240) and broadcast it to surrounding tags (S250 ).

Then, Tag 5 (Tag ID: 11 00 00 ) and Tag 6 (Tag ID: 11 00 11 ), which are tags whose tag ID starts with the query bit string '1100', respond to ' 0001 ' and ' 1000 ', respectively.

Meanwhile, the reader 100 can determine a collision bit generated in the response of each tag (S270), and the response information including the collision bit determined by the reader 100 is' ? 00? '.

Since the collision has occurred in the response, the reader 100 performs the collision processing step (S280, S300).

However, since the length of the bit string included in the response is M, the reader 100 can perform the prediction technique (S400).

Accordingly, the reader 100 may calculate two M-bit collision codes '0001' and '1000' corresponding to the two collision bits in the M-bit conversion code (S410).

Thereafter, the reader 100 may inversely convert each of the collision codes '0001' and '1000' of the calculated M bits into m bits of collision strings '00' and '11' corresponding thereto (S420).

In addition, the reader 100 combines each of the m-bit collision strings' 00 'and' 11 'calculated in the query bit string' 1100 'and transmits the tag ID' 110000 'and the tag ID' (Tag ID: 11 00 00) and Tag 6 (Tag ID: 11 00 11) that have transmitted the response via the calculated tag ID (S440).

On the other hand, after the ninth inquiry-response step is performed, the query-queue is empty, so that the reader 100 can complete the tag recognition (S220, S230).

Meanwhile, the tag providing method and the tag reader providing method according to the embodiment of the present invention can be implemented in the form of program instructions readable by a computer and stored in a computer readable recording medium. According to an embodiment of the present invention, The control program and the target program can also be stored in a computer-readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored.

Program instructions to be recorded on a recording medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of software.

Examples of the computer-readable recording medium include magnetic media such as a hard disk, a floppy disk and a magnetic tape, optical media such as CD-ROM and DVD, a floptical disk, And hardware devices that are specially configured to store and execute program instructions such as magneto-optical media and ROM, RAM, flash memory, and the like. The above-mentioned medium may also be a transmission medium such as a light or metal wire, wave guide, etc., including a carrier wave for transmitting a signal designating a program command, a data structure and the like. The computer readable recording medium may also be distributed over a networked computer system so that computer readable code can be stored and executed in a distributed manner.

Examples of program instructions include machine language code such as those produced by a compiler, as well as devices for processing information electronically using an interpreter or the like, for example, a high-level language code that can be executed by a computer.

The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

It is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. .

Claims (12)

An RFID tag recognition method using an M-ary query tree (where M is m ² and m is an integer of 2 or more)
The RFID tag receiving a query bit string broadcasted by the RFID tag reader;
When the query bit string of the RFID tag coincides with the prefix of the tag ID of the RFID tag, the subsequent m bit string of the prefix among the tag ID of the RFID is defined as M bits Generating a response including the converted M-bit conversion code, and a remaining one of the tag IDs of the RFID, excluding the m-bit string of the prefix and the subsequent m-bit string of the prefix;
Transmitting, by the RFID tag, the generated response to the RFID tag reader;
(a) adding a null bit string to a predetermined data structure in which an RFID tag reader can store a bit string;
(b) terminating the RFID tag reader when the data structure is empty;
(c) if the data structure is not empty, the RFID tag reader extracts one bit string from the data structure and sets the extracted bit string as a query bit string;
(d) broadcasting the query bit string set by the RFID tag reader;
(e) receiving, by the RFID tag reader, a response transmitted from at least a part of the at least one RFID tag that has received the query bit string;
(f) determining, by the RFID tag reader, a collision bit generated in the response;
(g) if the RFID tag reader does not generate a collision bit in the response, recognizing the RFID tag that transmitted the response based on the response;
(h) performing the collision processing step when the RFID tag reader generates a collision bit in the response; And
(i) repeating the steps (b) to (h) by the RFID tag reader,
The conflict processing step includes:
(h-1) If the collision bit is present in the M-bit conversion code among the bit strings included in the response, the M-bit collision code corresponding to each of the collision bits in the M-bit conversion code is expressed by Equation 2 ], And inversely transforming each of the calculated M-bit collision codes into an m-bit collision string by [Equation 1], combining the query string with the collision string of each m-bit inversely transformed to generate a subsequent query Generating a bit string and adding the generated subsequent query bit string to the data structure; And
(h-2) If the collision bit is not present in the M-bit conversion code, the M-bit conversion code is inversely transformed into an m-bit inverse transformed string by the following equation (1) Generating a subsequent query bit string comprising the m-bit inverted string, and adding the generated subsequent query bit string to the data structure.
[Equation 1]

(Where S is an m bit string, C is an M-bit conversion code (where M = 2 ^m ), and dec (S) is a value obtained by converting S into a decimal number)

[Equation 2]

Where b is the collision bit, P is the transform code of M bits, pos (P, b) is the position of the collision bit b in the transform code P of M bits, C is the collision bit of M bits corresponding to the collision bit b, Code)
The method of claim 1, wherein the step (h-2)
Wherein the number of bits from the immediately following bit of the M-bit conversion code to the immediately preceding impulse bit among the bit strings included in the response is mxk (where k is an integer equal to or greater than 1) k + 1) -1 or less,
Combining the query bit string, the inverse transformed m-bit inverse transformed string, and m x k bits immediately after the M-bit transform code among the bit strings included in the response to generate a subsequent query bit string The RFID tag comprising:
The method of claim 1, wherein the step (h-2)
Wherein the number of bits from the immediately following bit of the M-bit conversion code to the immediately preceding impulse bit among the bit strings included in the response is m x k + 1 (where k is an integer of 0 or more) (K + 1) or less,
A bit string formed by combining the query bit string, the inverse transformed m-bit inverse transformed string, and mxk bits immediately after the M-bit transform code among the bit strings included in the response, and a bit string Bits '0' and bit '1' are added to each collision bit included in the additional string in an additional string composed of bits from M + m × k + 1 to M + m × (k + 1) And generating a subsequent query bit string by combining the bit strings constituted by substitution.
2. The method according to claim 1,
If the length of the bit string included in the response is M or less,
The M-bit collision code corresponding to each collision bit in the M-bit conversion code is calculated by the above-mentioned [Expression 2], and each of the calculated M-bit collision codes is multiplied by the m- , Combines the query bit string and each of the m-bit collision strings reversed to calculate the tag ID of each RFID tag that transmitted the response, and transmits each response transmitted through the calculated tag ID Further comprising the step of recognizing the RFID tag,
The RFID tag reader includes:
Wherein the step (h-1) and the step (h-2) are not performed when the length of the bit string included in the response is M or less.
An M-th order query tree (where M is m ² and m is an integer of 2 or more)
A query receiving module for receiving a query bit string broadcasted by the RFID tag reader;
When the query bit string matches the prefix of the tag ID of the RFID tag, the subsequent m bit string of the prefix among the tag IDs of the RFID is converted into an M bit conversion code by the equation [1] A response generation module for generating a response including the M-bit conversion code and remaining bits of the tag ID of the RFID, excluding the m-bit string of the prefix and the subsequent m-bit string of the prefix; And
And a response transmission module for transmitting the generated response to the RFID tag reader.

[Equation 1]

(Where S is an m bit string, C is an M-bit conversion code (where M = 2 ^m ), and dec (S) is a value obtained by converting S into a decimal number)
An RFID tag reader using an M-th order query tree (where M is m ² and m is an integer of 2 or more)
An initialization module for adding a null bit string to a predetermined data structure capable of storing a bit string;
An end module for performing an end step of ending tag recognition when the data structure is empty;
A setting module for extracting one bit string from the data structure and setting the extracted bit string as a query bit string when the data structure is not empty;
A query transmission module for performing a query transmission step of broadcasting the set query bit string;
A response receiving module for receiving a response transmitted from at least one of at least one RFID tag that has received the query bit string;
A collision bit determination module for determining a collision bit generated in the response;
A recognition module for recognizing the RFID tag that transmitted the response based on the response when the collision bit is not generated in the response;
A conflict processing module for performing a conflict processing step when a collision bit is generated in the response; And
Wherein the end module, the setting module, the query transmission module, the response reception module, the collision bit determination module, the recognition module, and the collision processing module each include the end step, the setting step, the query transmission step, A collision bit determination step, a recognition step, and the collision processing step,
Wherein the collision processing module includes:
When the collision bit is present in the M-bit conversion code among the bit strings included in the response, an M-bit collision code corresponding to each collision bit in the M-bit conversion code is calculated by the following equation , Inverse transforms each of the calculated M-bit collision codes into an m-bit collision string by Equation 1, combines the collision strings of each of the inverse-transformed m-bit bits with the query bit string to generate a subsequent query bit string A first subsequent query generation module for adding the generated subsequent query bit string to the data structure; And
If the collision bit does not exist in the M-bit conversion code, inversely transforms the M-bit conversion code into an m-bit inverse transformed string by the following equation (1) A second subsequent query generation module for generating a subsequent query bit string including an inverse transform string and adding the generated subsequent query bit string to the data structure.

[Equation 1]

(Where S is an m bit string, C is an M-bit conversion code (where M = 2 ^m ), and dec (S) is a value obtained by converting S into a decimal number)

[Equation 2]

Where b is the collision bit, P is the transform code of M bits, pos (P, b) is the position of the collision bit b in the transform code P of M bits, C is the collision bit of M bits corresponding to the collision bit b, Code)
7. The method of claim 6, wherein the second subsequent query generation module comprises:
Wherein the number of bits from the immediately following bit of the M-bit conversion code to the immediately preceding impulse bit among the bit strings included in the response is mxk (where k is an integer equal to or greater than 1) k + 1) -1 or less,
An inverse transformed string of the inverse transformed m bits, and m x k bits immediately after the M-bit transform code among the bit strings included in the response to generate a subsequent query bit string, Tag Reader.
7. The method of claim 6, wherein the second subsequent query generation module comprises:
Wherein the number of bits from the immediately following bit of the M-bit conversion code to the immediately preceding impulse bit among the bit strings included in the response is m x k + 1 (where k is an integer of 0 or more) (K + 1) or less,
A bit string formed by combining the query bit string, the inverse transformed m-bit inverse transformed string, and mxk bits immediately after the M-bit transform code among the bit strings included in the response, and a bit string Bits '0' and bit '1' are added to each collision bit included in the additional string in an additional string composed of bits from M + m × k + 1 to M + m × (k + 1) And combines bit strings constituted by substitution to generate a subsequent query bit string.
The method according to claim 6,
The conflict processing module includes:
If the length of the bit string included in the response is M or less,
The M-bit collision code corresponding to each collision bit in the M-bit conversion code is calculated by the above-mentioned [Expression 2], and each of the calculated M-bit collision codes is m- , Combines the query bit string and the collision string of each m bits reversely transformed to calculate the tag ID of each RFID tag that transmitted the response, and transmits the response through the calculated n tag IDs And a prediction module for recognizing each RFID tag.
1. An RFID tag recognition method carried out in an RFID tag and using an M-th order query tree (where M is m ² and m is an integer of 2 or more)
The RFID tag receiving a query bit string broadcast from a predetermined RFID tag reader;
When the query bit string matches the prefix of the tag ID of the RFID tag, the following m bit string of the prefix among the tag ID of the RFID is converted into an M bit conversion code Generating a response including the transformed code of the M bits converted and the remaining bits of the tag ID of the RFID except for the prefix and the subsequent m bit string of the prefix; And
And the RFID tag transmits the generated response to the RFID tag reader.

[Equation 1]

(Where S is an m bit string, C is an M-bit conversion code (where M = 2 ^m ), and dec (S) is a value obtained by converting S into a decimal number)

An RFID tag recognition method performed in an RFID tag reader using an M-th order query tree (where M is m ² and m is an integer of 2 or more)
(a) adding a null bit string to a predetermined data structure in which the RFID tag reader can store a bit string;
(b) terminating the RFID tag reader when the data structure is empty;
(c) if the data structure is not empty, the RFID tag reader extracts one bit string from the data structure and sets the extracted bit string as a query bit string;
(d) broadcasting the query bit string set by the RFID tag reader;
(e) receiving a response sent from at least one of the at least one RFID tag that received the query bit string;
(f) determining a collision bit occurring in the response;
(g) if the collision bit is not generated in the response, recognizing the RFID tag that transmitted the response based on the response;
(h) performing a collision processing step when a collision bit occurs in the response; And
(i) repeating the steps (b) to (h) by the RFID tag reader,
The conflict processing step includes:
(h-1) If the collision bit is present in the M-bit conversion code among the bit strings included in the response, the M-bit collision code corresponding to each of the collision bits in the M-bit conversion code is expressed by Equation 2 ], And inversely transforms each of the calculated M-bit collision codes into an m-bit collision string by the following equation (1), combines the collision string of each m-bit reversed with the query bit string to obtain n Generating a subsequent query bit string, and adding the generated n subsequent query bit strings to the data structure; And
(h-2) If the collision bit is not present in the M-bit conversion code, the M-bit conversion code is inversely transformed into an m-bit inverse transformed string by the following equation (1) Generating a subsequent query bit string comprising the m-bit inverted string and adding the generated subsequent query bit string to the data structure.

[Equation 1]

(Where S is an m bit string, C is an M-bit conversion code (where M = 2 ^m ), and dec (S) is a value obtained by converting S into a decimal number)

[Equation 2]

Where b is the collision bit, P is the transform code of M bits, pos (P, b) is the position of the collision bit b in the transform code P of M bits, C is the collision bit of M bits corresponding to the collision bit b, Code)
12. A computer-readable recording medium having recorded thereon a program for performing the method according to claim 10 or claim 11.

Images