CN102332081A - Based on the carrier sense multiple access protocol in the radio frequency identification of reader - Google Patents
Based on the carrier sense multiple access protocol in the radio frequency identification of reader Download PDFInfo
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- CN102332081A CN102332081A CN201110250862A CN201110250862A CN102332081A CN 102332081 A CN102332081 A CN 102332081A CN 201110250862 A CN201110250862 A CN 201110250862A CN 201110250862 A CN201110250862 A CN 201110250862A CN 102332081 A CN102332081 A CN 102332081A
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Abstract
The present invention relates to a kind of based on the carrier sense multiple access protocol in the radio frequency identification of reader; The present invention is used for communication consumption and the electronic tag conflict consumption that radio RF recognition technology reduces reader, to reach higher channel utilization and label reading rate.The present invention adopts reader to carry out carrier sense, and gives the electronic tag in the communication range with channel conditions through a small amount of coded data periodic broadcast, reaches the purpose that reduces channel seizure ratio; Electronic tag determines the probability of competitive channel when each cycle begins, thereby makes the competition probability of electronic tag be in optimum state, to reach the purpose that reduces collision probability.Electronic tag sends the lightweight data earlier when competitive channel, after the acquisition channel right to use, the heavyweight data of redispatching are accomplished communication, thereby reduce the unnecessary channel occupancy that takes place because of conflict, thereby increase the electronic tag reading rate.
Description
Technical field
The present invention relates to a kind ofly can reduce radio frequency identification (RFID; Radio Frequency IDentification) reader communication consumption and electronic tag conflict consume in the system, improve the carrier sense multiple access protocol of channel utilization and electronic tag reading rate.The invention belongs to radio RF recognition technology, wireless communication technology field.
Background technology
Radio frequency identification (hereinafter to be referred as RFID) technology is a kind of contactless automatic identification technology, and it is through the automatic recognition objective object of radiofrequency signal and obtain related data, and identification work need not manual intervention, can work in various rugged surroundings.The RFID technology has the characteristic that can discern high-speed moving object and can discern a plurality of labels simultaneously.The RFID technology is widely used in various fields such as large supermarket, logistics, airport and indoor positioning.Typical R FID system comprises two elements, i.e. reader and electronic tag (abbreviation label).
In real work, when reader need transmit mass data and controls electronic tag, channel utilization can descend, and the electronic tag reading rate also can descend thereupon.Electronic tag can be chosen in a time period according to the competition probability and whether transmit data, if two or above electronic tag transmit simultaneously, then channel confliction takes place.After channel confliction took place, this time period can be wasted, thereby channel utilization also is lowered.Channel confliction is a problem that often runs in the RFID technology.Simultaneously, the information of electronic tag transmits the utilization factor that probability has determined channel: too high probability can cause the large volumes of channels conflict, and too low probability can cause channel idle, and therefore, selecting an optimum competition probability also is a very important problem.
When reader needs transferring large number of data; Under the binary search tree protocol; Reader need transmit the data with several grades of amounts such as electronic tags at least, just might discern a label, if the reader transfer rate is very low; So most channel all will be taken by reader, and the read rate of electronic tag also just decreases.In addition, compete section at the same time simultaneously, can cause unlimited conflict and label not to be identified when two electronic tags.
The present invention is intended to propose a kind of carrier sense multiple access protocol based on reader, reduces the consumption that channel confliction brings, and the volume of transmitted data when reducing reader and transmitting mass data and control electronic tag, thereby improves channel utilization and label read rate.
Find through retrieval; The RFID industrial standard mainly reads electronic tag through two kinds of agreements at present; ALOHA agreement and binary search tree protocol; Wherein, the needs of ALOHA agreement could be adjusted label transmission probability through the long period, the binary search tree protocol then need reader often to send mass data to control electronic tag.The identical point of these two agreements is all will once transmit the data in all electronic tags, so it to be very big to clash the possibility that can cause channel wastage.At present existing related application relates to and reduces many labels collision conflicts, with the present invention relatively after, obtain to draw a conclusion:
Application number is 200810218611.8; The applying date is that the domestic application for a patent for invention on October 24th, 2008 discloses a kind of multi-label anti-collision method based on packet dynamic frame and binary tree search that is used for rfid system, and this method comprises number of labels estimation stages and tag recognition stage.The number of labels estimation stages is accomplished the estimation to unidentified number of labels; The tag recognition stage is chosen optimum packet count and every group of optimum frame length according to the estimated value of unidentified number of labels; Label distribution is discerned in some groups frame period successively; And adopt binary tree search to discern, and then all labels have been discerned to the label in every group of time slot that bumps.This invention need be estimated number of labels, competes probability thereby choose optimum, has reduced reading rate to a certain extent; The present invention need not pass through number of labels and estimate, only according to the channel status of each time period broadcasting of reader, the competition probability of electronic tag just can reach optimum in the extremely short time, can improve the reading rate of electronic tag.
Application number is to be many label identification methods that on 07 08th, 2010 domestic application for a patent for invention discloses a kind of RFID reader 201010221127.8 applyings date.May further comprise the steps: step 1 read write line sends sense command to population of tags; Label is selected one of them time-gap number after receiving sense command at random the sequence of time slots of (2Q-1) from time slot 0 to time slot, generate a sequence of time slots with binary data of 2Q bit as label simultaneously; After step 2 read write line is received the sequence of time slots of label transmission, the bit conflict of the sequence of time slots of tags detected; Step 3 read write line begins identification label according to busy time-gap number list item, and read write line sends inquiry command Query (S1) successively and gives population of tags according to time-gap number order from small to large.Because the present invention need not collect the time-gap number that electronic tag produces, therefore there is not the additive decrementation that brings because of the conflict of time slot label.Simultaneously; Adopt the reader of the method for the invention electronic tag in need only the initialize communications scope once; Send detected channel status in each time period through minimum data volume (< 1 byte) then; Greatly reduce reader and send the time loss that data are brought, therefore the recognition rate of electronic tag increases substantially.
Application number is that to be that the domestic application for a patent for invention on October 27th, 2010 discloses 201010520775.3 applyings date a kind of with the electronic tag classification, then the method through binary search tree algorithm identified electronic tag.The label cutting procedure can be an ALOHA frame or other signal frames, and label selects a time slot to send ID at random in this process, and it act as the population of tags that all labels constituted in the read write line scope is divided into several separate little population of tags.The label search procedure can be made up of a plurality of message frames, and the particular crash time slot in each frame corresponding label cutting procedure can be realized the identification one by one to label through methods such as recoverable binary tree searchs in this frame.The present invention adopts disposable inquiry; Each time period only need be sent minute quantity data (< 1 byte) and carried out synchronously and the method for broadcast channel state afterwards; Therefore reduce the communication consumption that electronic tag is classified step by step, reduced the data traffic volume of reader, improved channel utilization.
The present invention proposes a new communication protocol, can solve in the radio frequency identification system reader communication consumption and electronic tag conflict and consume problems such as excessive, increase channel utilization and electronic tag read rate.
Summary of the invention
Technical matters to be solved by this invention is; How effectively to improve label reading efficiency and reading rate in the radio-frequency recognition system,, generally do not possess the ability of carrier sense promptly in view of the electronic tag simplicity of design; How under electronic tag can't the situation of monitor channel; Make electronic tag know channel conditions, thereby adopt an effective measure, alleviate above-mentioned channel confliction problem in wireless communication field; Simultaneously, reduce the reader communication data volume.
For realizing that the technical scheme that above-mentioned purpose adopted is: through RFID reader monitor channel, and radio channel state is broadcast to electronic tag, makes electronic tag will compete probability automatically and transfer to optimum; Electronic tag transmits remaining data again through lightweight data contention channel after the competition success; Reader only need transmit low volume data promptly can begin identification label, and sends the data less than 1 byte in each cycle and come the broadcast channel situation.
Because the electronic tag simplicity of design, it does not possess the ability of carrier sense, thus the present invention collects through reader and the statistical channel situation after, again channel conditions is sent to the electronic tag in the communication range, reach the carrier sense purpose of electronic tag thus.The RFID reader can be provided with the competition probability of electronic tag; Also can periodically send the competition probability of Data Control electronic tag, make electronic tag can obtain channel status in real time, according to channel status adjustment competition probability; Make the competition probability be in optimum state, increase channel utilization with this.
With respect to traditional radio frequency identification agreement, the present invention makes electronic tag come competitive channel with the lightweight data, after the competition success, transmits the residuals weight grade data again, and design can reduce because the waste that channel confliction causes like this.
In real work, one has three kinds of channel conditions, vacant channels, collision channels, available channel.Vacant channels representes not have electronic tag to send data, does not promptly have electronic tag to be at war with.In this case; Reader need wait for that certain hour has judged whether that label transmits data; Stand-by period is directly proportional with data length, if promptly data are long, the stand-by period of reader will be corresponding longer; So when electronic tag with a small amount of data contention the time, reader only need be waited for the short period.In like manner, carry out data transmission when intending, when promptly electronic tag is at war with more than an electronic tag; Be that channel confliction takes place; Because what label adopted is to come competitive channel with the lightweight data earlier, i.e. data " weak point ", so reader need not waited for the long time yet.But when the channel time spent, expression has only an electronic tag competition, and this electronic tag will be identified.
Reader needs periodically to send the order of " beginning identification " under the general conventional transmission agreement that adopts of rfid system, and this order will be confirmed the coding and decoding mode of reader and electronic tag, and the competition probability of initialization electronic tag etc. are so data volume is bigger.The present invention allows reader only to send once " beginning to discern " and orders initialization, only needs periodically transmitting channel state afterwards, regulates the competition probability automatically by electronic tag, and whether selection sends data, continuation is sent and still kept former waiting status.
The present invention is a kind of novel based on the carrier sense multiple access protocol in the radio frequency identification of reader, and the beneficial effect that can reach is following:
Reach the optimum competition of electronic tag probability in short time, reduce channel confliction;
Reduce the consumption that channel confliction brings in single time period, improve channel utilization, improve the reading rate of electronic tag;
Reduce the data traffic volume of reader, give electronic tag more call duration time.
Description of drawings
Below in conjunction with accompanying drawing and embodiment the present invention is further specified.
Fig. 1 is based on the running of the carrier sense multiple access protocol in the radio frequency identification of reader figure.
Fig. 2 is the electronic tag state transition graph.
Embodiment
Below in conjunction with accompanying drawing the present invention is done further explanation.
Reader " begins identification " instruction begins identification through sending wireless signal, and will be divided into the discrete time period time, whether selects competitive channel at each electronic tag of each time period through probability.Vacant channels, available channel and collision channels are represented not have the electronic tag competition respectively, are had only an electronic tag to carry out data transmission and the competition of a plurality of electronic tag.Having only an electronic tag through under the situation of lightweight data contention, reader can notify this label to continue to send (other electronic tags stop to send simultaneously), and this is notified electronic tag can continue to send remaining data.
The lightweight data of a plurality of electronic tags possibly cause conflict, if cause conflict, can be broadcast to electronic tag after reader listens to, and all electronic tags that clash can be adjusted competition probability and competitive channel again, and promptly electronic tag is known channel conditions.
As shown in Figure 1; Reader comes the electronic tag in the initialize communications scope through sending " beginning identification " order, and initialization comprises that the electronic tag initialization is set competes probability, confirms transfer rate etc.; After the initialization; Reader will be divided into the discrete time period time, and in each time period, channel has three kinds of states:
Vacant channels: reader does not listen to the data transmission of any electronic tag;
Collision channels: reader listens to the data transmission of a plurality of electronic tags;
Available channel: reader listens to the data transmission of an electronic tag.
In order to represent this three kinds of channel statuss, can adopt simple code sign state, for example encode and be broadcast to electronic tag with two data bit.Electronic tag obtains channel status in the following manner:
00: reader is not received any data;
11: reader is received the data transmission more than an electronic tag;
01: reader is received the lightweight data transmission of an electronic tag;
10: reader is received the heavyweight data transmission of an electronic tag.
For the competition probability of electronic tag, competition window length d w of each electronic tag storage is in each time period; Electronic tag can be from [0; Dw-1] in optional numeral, when this numeral of selecting was 0, this electronic tag can send lightweight data contention channel.The competition window length d w of electronic tag can change as follows:
If current is collision channels, electronic tag can double the length of competition window;
If current is available channel, electronic tag can keep competition window length constant;
If current is vacant channels, can the reduce by half length of competition window of electronic tag.
If promptly channel is empty, then electronic tag will compete probability and subtract doubly, if channel can be used, then electronic tag keeps current competition probability, if channel clashes, then electronic tag will be competed probability and double, and make electronic tag be in optimum with this and compete probability.
, electronic tag can be in waiting status when receiving the order that the RFID reader begins to discern.Under waiting status, electronic tag can if begin competition, can get into transmit status, if competition success can be sent remaining data and got into read states according to the probabilistic determination channel that whether is at war with; If do not compete through probability calculation, can continue to keep waiting status so, perhaps competition failure can be returned waiting status and promptly keep ortho states.
Fig. 2 representes the state transition graph of electronic tag.At first, all electronic tags get into waiting status after receiving order, when the competition numeral is 0; Electronic tag can get into transmit status; And send lightweight data contention channel, if competition success promptly is in the channel upstate; Can continue to send the residuals weight grade data and get into read states, getting into, the electronic tag of read states will no longer carry out channel competition.Be that electronic tag only just can send the heavyweight data division under the situation that channel can be used,, reduce conflict with this and consume, increase channel utilization and reading rate so the heavyweight data division can not cause conflict.When the competition numeral was not 0, electronic tag can keep waiting status, and in next time period competitive channel again.
Claims (9)
1. one kind based on the carrier sense multiple access protocol in the radio frequency identification of reader; It is characterized in that: based on radio RF recognition technology; Carry out channel-monitoring by reader, after the order initialization, need only be periodically with being broadcast to electronic tag behind the radio channel state coding; After electronic tag obtains channel conditions; If the transmission of label code is carried out in decision; Then adopt the lightweight data to carry out channel competition, will compete probability automatically and transfer to optimum, the remaining data of after competition success, redispatching, thus realize the csma among the RFID; Practice thrift the coordination consumption of reader and the conflict consumption of electronic tag, to improve channel utilization and the speed that reads electronic tag.
2. according to claim 1 a kind of based on the carrier sense multiple access protocol in the radio frequency identification of reader; It is characterized in that: through reader in initialization; After promptly sending once " beginning identification "; Just begin periodically to collect and the statistical channel situation, with sending to the electronic tag in the communication range behind the channel conditions coding, reach the carrier sense purpose and the network operation of electronic tag thus again.
3. according to claim 2 a kind of based on the carrier sense multiple access protocol in the radio frequency identification of reader; It is characterized in that: reader identifies radio channel state through simple code; Send coding to electronic tag then, make electronic tag obtain channel conditions.
4. according to claim 1 a kind of based on the carrier sense multiple access protocol in the radio frequency identification of reader, it is characterized in that: reader is monitor channel and control cycle length periodically.
5. according to claim 1 a kind of based on the carrier sense multiple access protocol in the radio frequency identification of reader; It is characterized in that: the data that electronic tag will send are divided into gently, heavyweight data two parts, send lightweight part competitive channel earlier, and the heavyweight of redispatching is partly accomplished communication; And react according to agreement; When the success of lightweight data contention, continue to send the heavyweight data, when the lightweight data contention is failed, then resend, or maintain the original state.
6. according to claim 5 a kind of based on the carrier sense multiple access protocol in the radio frequency identification of reader; It is characterized in that: the lightweight of a plurality of electronic tags is partly competed and possibly caused conflict; If cause conflict, after listening to, reader can be broadcast to electronic tag, and all electronic tags that clash can be adjusted competition probability and competitive channel again; Make electronic tag know channel conditions, and carry out peak optimization reaction and increase channel utilization.
7. according to claim 5 a kind of based on the carrier sense multiple access protocol in the radio frequency identification of reader; It is characterized in that: electronic tag only just can send the heavyweight data division under the situation that channel can be used; The heavyweight data division can not cause conflict; Consume thereby reduce conflict, increase channel utilization and reading rate.
8. according to claim 1 a kind of based on the carrier sense multiple access protocol in the radio frequency identification of reader, it is characterized in that: if channel conditions for empty, then electronic tag will be competed probability and reduce by half; If channel conditions is available, then electronic tag keeps current competition probability; If channel clashes, then electronic tag will be competed probability and double, and make electronic tag be in optimum competition probability with this.
9. according to claim 1 a kind of based on the carrier sense multiple access protocol in the radio frequency identification of reader, it is characterized in that: reader can be provided with the competition probability of electronic tag, and can periodically send the competition probability of Data Control electronic tag.
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| CN111339794A (en) * | 2020-03-24 | 2020-06-26 | 中山大学 | Anti-collision resource competition method based on tag number, mobile reader and readable storage medium |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105740744A (en) * | 2016-01-29 | 2016-07-06 | 华东师范大学 | Variable-transmission speed double-frequency RFID anti-collision communication method |
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| CN110113733A (en) * | 2019-03-29 | 2019-08-09 | 中山大学 | A kind of RFID reader anticollision graph coloring two-stage distribution method |
| CN110113733B (en) * | 2019-03-29 | 2021-06-29 | 硅湾工业互联网工厰(深圳)有限公司 | Two-stage distribution method for coloring anti-collision graph of RFID reader |
| CN111339794A (en) * | 2020-03-24 | 2020-06-26 | 中山大学 | Anti-collision resource competition method based on tag number, mobile reader and readable storage medium |
| CN111339794B (en) * | 2020-03-24 | 2023-06-27 | 中山大学 | Anti-collision resource competition method based on number of tags, mobile reader and readable storage medium |
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Application publication date: 20120125 |