CN102663332A - Multi-label anti-collision guiding identification method for RFID system - Google Patents

Abstract

The invention, which relates to the radio frequency identification (RFID) field in the internet of things, discloses a multi-label anti-collision guiding identification method for an RFID system. The method mainly comprises the following steps that: a reader sends a query command, all labels return whole label numbers and the reader receives data; after the reader determines that there is collision, a binary tree is obtained by splitting at a highest collision bit, wherein a left sub-tree branch is 0 and a right sub-tree branch is 1, and the reader issues a query instruction again and a query sequence is realized based on a guiding mode; and according to the guide mode, a branch with fewest collision bits is searched first. According to the invention, backtracking searching of a dynamic binary identification method can be avoided and the number of times for query is reduced; identification efficiency of a reader on multiple labels is substantially improved; and the provided method is suitable for rapid identification of the multiple electronic labels by the reader in an RFID system.

Description

A kind of multiple labels anti-collision guiding recognition methods that is used for rfid system

Technical field

The present invention relates to the RFID field of radio frequency identification in the Internet of Things, relate in particular to a kind of multiple labels anti-collision guiding recognition methods that is used for rfid system.

Background technology

Internet of Things is the important component part of generation information technology, and its English name is " The Internet of things ".As its name suggests, " Internet of Things is exactly the internet that the thing thing links to each other ".This has the two-layer meaning: the first, and the core and the basis of Internet of Things remain the internet, are extension and the network of expansion on the basis, internet; The second, its user side extends and has expanded between any article and the article, carries out message exchange and communicates by letter.Therefore; The definition of Internet of Things is through information sensing equipment such as RF identification (RFID), infrared inductor, GPS, laser scanners; Agreement by agreement; Be connected any article with the internet, carry out message exchange and communicate by letter, to realize a kind of network intellectuality identification, location, tracking, monitoring and the management of article.

RFID (Radio Frequency Identification, radio frequency identification) system mainly is made up of reader, label and data processing unit.Label is used to deposit the identification code that is identified object, and reader is accomplished the radio communication with label, and connects data processing unit.RFID reads the data in the electronic tag through reader, accomplishes object is discerned automatically.Compare with traditional recognition technology, the reader of RFID can communicate with a plurality of electronic tags simultaneously, thereby identification efficiency is high more a lot of than traditional recognition method.If electronic tag is within the read range of a reader, will reply the inquiry of this reader.When a reader read two or more electronic tag simultaneously, the collision of label will take place.When the label collision took place, reader can not correctly read the data in the electronic tag, causes the failure of communication.The label that failure takes place will resend, and can lose time like this.Therefore rfid system need solve the collision problem between a plurality of labels.

At present in the middle of rfid system label anti-collision method mainly by time division multiplex, frequency division multiplexing, CDMA multiplexing and four kinds of methods of space division multiplexing; Wherein utilize maximum time-division multiplexing methods, time division multiplex mainly adopts based on the ALOHA method of probability with based on the binary approach of confirming type.Based on the ALOHA method of probability is when collision takes place, and redispatches after in the time of one section of each electronic tag random wait, till all electronic tags are read.The ALOHA algorithm is simple, but efficiency ratio is lower, generally is of little use.Binary approach based on confirming type is to use multi-label anti-collision method the most widely.In the method; Unique sequence number (ID) is arranged in each electronic tag; Each of ID number is by O or 1 forms, and electronic tag sends to reader with own ID number, and reader judges that again which electronic tag need send the ID number perhaps data of which label transmission oneself of oneself.Reader judges that the collision position is to adopt Manchester's cde, if the value of the same position of two above labels is not simultaneously, reader is not sure of this value, whom occurs in thereby obtain collision.

The main thought of scale-of-two collision-proof method is that reader sends query statement, and the electronic tag response is not if reader receives the ID of electronic tag; Expression does not have label to send, if having only a tag responses, the collision of label then can not occur; Directly select this label, if there be plural ID number, label will bump; At this moment the extreme higher position with collision is 0, and all are 1 less than collision most significant digit value, according to this data number; Reader resends query statement, is less than or equal to the electronic tag of data number to reply, and oneself ID number sent to reader.Repeat top process, do not bump up to label, reader is selected will to be sent the electronic tag of data and receive the data from this ID label.The disadvantage of scale-of-two collision-proof method is that the figure place of each inquiry is the same with the figure place of label, and repeats inquiry, so its recognition efficiency is very low.The binary collision-proof method is the improvement of scale-of-two collision-proof method, and its basic thought is to reduce the inquiry figure place.Reader only sends the position of front, the highest collision position when inquiry, do not send later position, collision position, and the response bits of label also reduces simultaneously, only need transmit later position, collision position during tag responses.It is thus clear that the binary collision-proof method has reduced the transmission of redundant data, improved the recognition efficiency of label.But the binary collision-proof method does not change the repeatedly repetition query script of scale-of-two collision-proof method.Judge whether quality is mainly seen two aspect performances to a scale-of-two RFID collision-proof method, the one, the traffic of reader in identifying.The traffic mainly comprises the figure place of query statement and the figure place of electronic tag response; The 2nd, the inquiry times of reader, the reader inquiry times is many more, and the recognition efficiency of rfid system is just low more so.The binary collision-proof method has reduced the traffic in the identifying, but does not reduce inquiry times, so its recognition efficiency is not high yet.

Summary of the invention

The objective of the invention is the defective that exists in the binary recognition methods in order to overcome; A kind of multiple labels anti-collision guiding recognition methods that is used for rfid system is provided; This method guiding reading device is along the method identification electronic tag of optimum; Make the tag recognition multiplicity reduce, improve the recognition efficiency of label.

The objective of the invention is to realize like this:

One, rfid system (abbreviation system)

Rfid system comprises data processing unit, reader, antenna and electronic tag;

Its annexation is:

Data processing unit is connected with reader through network, and reader is through its antenna transmission radiofrequency signal, and the electronic tag received RF signal responds the instruction of reader as requested.

Two, a kind of multiple labels anti-collision guiding recognition methods (abbreviation method) that is used for rfid system

This method comprises the following steps:

1. reader initialization system, all labels are in active state;

2. reader sends querying command, and all labels return whole said tag, and reader receives data; As have only the response of label, then this label of Direct Recognition; As do not have the label response, then expression does not have identification signal, end of identification; If any two above label responses, then bump, and through Man Tesite code identification collision position;

3. reader divides a binary tree in the highest collision position after judgement has the collision of existence, and left subtree branches into 0, and right subtree branches into 1, and reader sends query statement again and search order carries out according to guidance mode;

4. reader is safeguarded two data structural tables, and promptly OPEN table (opening) and CLOSED show (closing), and the node that the OPEN table generates when placing collision, CLOSED show to place the node that will expand or the node of having expanded;

5. after a plurality of labels bump, split into two nodes, put into the OPEN table; Expanding node carries out according to guidance mode; Promptly according to how much the guiding of collision bit, the minimum node in collision position is placed on the stem of OPEN table, remaining is successively placed in the OPEN table;

6. according to the binary tree after dividing, the query statement of reader changes 0 or 1 transmission respectively that the highest collision position prefix adds the collision position into, if having only a label response, then this label is identified, otherwise divides a binary tree once more in the collision position;

7. be placed in the OPEN table dividing the node that, reader at every turn from the OPEN table stem select a node to put into the CLOSED table, and send corresponding query statement, up to the OPEN table for empty;

Described guidance mode is with the advanced line search of the minimum branch in collision position.

Principle of work of the present invention is:

Binary recognition methods subject matter is that inquiry times is more, and this is that when the label figure place was more, the number of times of recalling was more because this method need repeatedly turn back to the initial conditions repeat search.Basic thought of the present invention is to avoid the binary recognition methods to recall, and adopts the guiding method, and the guiding reading device is minimum querying node along the collision position, thereby has avoided recalling inquiry, has improved search efficiency.

Compared with prior art, the present invention has following advantage and beneficial effect:

1. avoid the search of recalling of binary recognition methods, reduced the inquiry times of reader;

2. significantly improved the recognition efficiency of reader to many labels.

The present invention is applicable to that reader is to the quick identification of a plurality of electronic tags in the rfid system.

Description of drawings

Fig. 1 is the block diagram of rfid system;

Fig. 2 is the specific embodiment process flow diagram of this method;

Wherein:

10-rfid system,

11-data processing unit, 12-reader, 13-antenna, 14-label.

Embodiment

Specify below in conjunction with accompanying drawing and embodiment:

One, system

1, overall

Like Fig. 1, rfid system 10 comprises data processing unit 11, reader 12, antenna 13 and electronic tag 14;

Its annexation is:

Data processing unit 11 is connected with reader 12 through network, and reader 12 sends radiofrequency signal through its antenna 13, and electronic tag 14 received RF signals respond the instruction of reader 12 as requested.

Its principle of work is:

A rfid system 10 comprises data processing unit 11, reader 12 and the label 14 that background process is used, and reader 12 is through antenna 13 launching electromagnetic waves, and the request of electronic tag 14 response readers 12 sends to reader 12 with information; If a plurality of labels respond simultaneously, then bump.

2, functional block

1) data processing unit 11

Data processing unit 11 is communicated by letter with reader 12 through network, and obtains the information of electronic tag 14 in real time, then the information that is obtained is handled.

2) reader 12

Reader 12 is claimed requestor again; Reader 12 is to electronic tag 14 launching electromagnetic waves; Electronic tag 14 is received behind the electromagnetic wave that reader 12 launched the order request according to reader 12; The information that oneself needs to launch back reader 12 is carried out backscattered modulation to electromagnetic wave; Information is mail to reader 12, and reader 12 receives the also reflected signal of demodulation electronic tag 14, reads 14 information transmitted of electronic tag; Reader 12 sends query statement through antenna 13.

3) electronic tag 14

Electronic tag 14 is claimed transponder again; Each electronic tag 14 all has a unique identifier, and this identification code is used to identify 14 information of adhering to object of electronic tag; Electronic tag 14 receives query statement and replys.

Two, the specific embodiment flow process of this method

Like Fig. 2, this method comprises the following steps:

1. begin 201, reader REQUEST 202, all label responses 203.

2. judging whether label collides, is then to change to jump to step 4., otherwise gets into step 3.;

3. this label is identified, and reader sends SELECT 210 instructions and chooses this label, after execution READ-DATA instruction 211 runs through data, carries out UNSELECT instruction 212 and makes label be in dormant state;

4. send query statement 205;

5. judge that whether the OPEN table is table sky 206, is then to get into step 9., otherwise gets into step 6.;

6. from OPEN table, 207 choose a node, the order of choosing is the preferential minimum node in collision position of selecting;

7. reader REQUEST208;

8. judging whether to collide 209, is then to change to jump to step 4., jumps to step 3. otherwise change;

9. finish 213.

Concrete identifying to this instance is following:

Existing hypothesis has 4 electronic tags, and their said tag is respectively:

Tag1 (10110011), Tag2 (10110110), Tag3 (10100011) and Tag4 (11100011);

1. reader send request instruction REQUEST ( NULL, 8) and 202,4 labels reply simultaneously, bump, and reader can be judged the position that bumps according to the Man Tesite coding, and result of determination is 1X1X0X1X, and wherein X representes the collision position.Totally 4 bump, and the highest collision position is the 6th, and with the 6th for putting 0 and 1, according to the highest collision, reader will send query statement REQUEST (10,6) and REQUEST (11,6) respectively next time;

2. reader sends query statement REQUEST (10,6), Tag1 (10110011); Tag2 (10110110), Tag3 (10100011) response bumps again; Label returns 110011,110110 and 100011 respectively; Reader is judged the collision position according to the Man Tesite coding, and the result is 1X0X1X, and the collision position is the 4th, 2,0.The highest collision position is the 4th;

3. reader sends query statement REQUEST (11,6), have only Tag4 (11100011) response, so this label is identified;

4. reader sends instruction REQUEST (1010,4), Tag3 (10100011) response, and this label is identified;

5. reader sends instruction REQUEST (1011,4), Tag1 (10110011), and Tag2 (10110110) response, and return 0011 and 0110, and bumping, the collision result is 0XX0, most significant digit is the 2nd;

6. reader sends instruction REQUEST (101100,2), and Tag1 (10110011) is identified;

7. reader sends instruction REQUEST (101101,2), and Tag2 (10110110) is identified;

8. identification finishes.

Claims (1)

1. multiple labels anti-collision guiding recognition methods that is used for rfid system, rfid system comprises data processing unit, reader, antenna and electronic tag; Data processing unit is connected with reader through network, and reader is through its antenna transmission radiofrequency signal, and the electronic tag received RF signal responds the instruction of reader as requested;

It is characterized in that this method comprises the following steps:

1. reader initialization system, all labels are in active state;

2. reader sends querying command, and all labels return whole said tag, and reader receives data; As have only the response of label, then this label of Direct Recognition; As do not have the label response, then expression does not have identification signal, end of identification; If any two above label responses, then bump, and through Man Tesite code identification collision position;

3. reader divides a binary tree in the highest collision position after judgement has the collision of existence, and left subtree branches into 0, and right subtree branches into 1, and reader sends query statement again and search order carries out according to guidance mode;

4. reader is safeguarded two data structural tables, and promptly OPEN table (opening) and CLOSED show (closing), and the node that the OPEN table generates when placing collision, CLOSED show to place the node that will expand or the node of having expanded;

5. after a plurality of labels bump, split into two nodes, put into the OPEN table; Expanding node carries out according to guidance mode; Promptly according to how much the guiding of collision bit, the minimum node in collision position is placed on the stem of OPEN table, remaining is successively placed in the OPEN table;

6. according to the binary tree after dividing, the query statement of reader changes 0 or 1 transmission respectively that the highest collision position prefix adds the collision position into, if having only a label response, then this label is identified, otherwise divides a binary tree once more in the collision position;

7. be placed in the OPEN table dividing the node that, reader at every turn from the OPEN table stem select a node to put into the CLOSED table, and send corresponding query statement, up to the OPEN table for empty;

described guidance mode is with the advanced line search of the minimum branch in collision position.

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