CN103577784B - Active RFID reader collision-proof method and system based on multi-radio - Google Patents
Active RFID reader collision-proof method and system based on multi-radio Download PDFInfo
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- CN103577784B CN103577784B CN201310606703.4A CN201310606703A CN103577784B CN 103577784 B CN103577784 B CN 103577784B CN 201310606703 A CN201310606703 A CN 201310606703A CN 103577784 B CN103577784 B CN 103577784B
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Abstract
The invention discloses the active RFID reader collision-proof method of a kind of multi-radio and system, the method adopts anticollision For Spread Spectrum Sequences to communicate mainly through arranging active RFID tag and reader in RFID system, and multiple radio-frequency module is set in reader, each radio-frequency module is merely able to receive corresponding anticollision For Spread Spectrum Sequences, collides thus reasonably avoiding label information.By the dynamic slot ALOHA algorithm in conjunction with code division technology, time division technique and improvement, improve treatment effeciency and the processing speed of electronic tag, and by adopting direct spreading sequence technical communication, improve the safety and reliability of system work and anticollision performance.
Description
Technical field
The invention belongs to twireless radio-frequency communication technical field, be specifically related to the design of a kind of active RFID reader collision-proof method based on multi-radio and system.
Background technology
RF identification (RadioFrequencyIdentification is called for short RFID) technology is the technology that a kind of Space Coupling by radiofrequency signal (alternating magnetic field or electromagnetic field) realizes contactless automatic identification.The core component of radio-frequency recognition system has reader, and (reception comes from the information of electronic tag, and can by being connected with computer, realize the tension management of whole application system) and electronic tag (to the information of reader long range radio transmissions self storage, to identify the identity of article, people and utensil that electronic tag represents).
During radio-frequency recognition system work, it is possible to having more than one electronic tag and be simultaneously in the sphere of action of reader, if so had, two or more electronic tag there will be communication contention aware when sending data simultaneously, data interfere collision；Equally sometimes being also possible within the working range that multiple electronic tag is in multiple reader, the data communication between them also can cause data to disturb.In order to prevent the generation of these conflicts, needing to arrange certain related algorithm in radio-frequency recognition system, solve this data collision problem, these algorithms are referred to as anti-collision algorithm.
In RFID system, collision has following characteristics: the transmission time that between reader and electronic tag, packet is total is determined by size and the baud rate of packet, and propagation delay is negligible；RFID system includes substantial amounts of electronic tag and is dynamic (at any time likely beyond reader scope), communicated by the way active channel of competitive excitation, can not communicate with reader when electronic tag is not activated by reader, it is unique for this master slave relation of RFID system, once electronic tag is identified, it is possible to and communicate with point-to-point pattern between reader.
Need to read accurately up to a hundred even more than a thousand sheets electronic tags when processing these electronic tags in active RFID system within several seconds, but RFID reader anti-collision algorithm of the prior art is all use time division technique to prevent collision, when magnanimity label, the simple time using time division technique must be greatly prolonged identification label, drain cap simultaneously, the situation of dish label becomes apparent from by mistake, the present invention uses multiple radio transmitting and receiving chip, utilize the protocol processes of code division technology and CPU, the parallel information receiving many group labels, at double improve reader take inventory efficiency and accuracy rate.
Summary of the invention
The technical problem to be solved is the shortcoming existed for RFID reader collision-proof method in prior art and system and proposes a kind of active RFID reader collision-proof method based on multi-radio and device.
This invention address that technical problem the technical scheme is that the active RFID reader collision-proof method based on multi-radio, specifically include:
Wake module in S1, reader sends wake-up signal to the active RFID tag in reader coverage；
S2, active RFID tag monitor ambient signals through periodic sleep state immediately after reviving, if listening to the wake-up signal that wake module sends, then use anticollision For Spread Spectrum Sequences to send signal to the module for reading and writing in reader；Otherwise label is again introduced into periodic sleep state；
There is multiple radio-frequency module in S3, module for reading and writing, each radio-frequency module is able to receive that a kind of anticollision For Spread Spectrum Sequences, after radio-frequency module receives corresponding anticollision For Spread Spectrum Sequences information, then sends ACK acknowledgement information to active RFID tag；
If the ACK acknowledgement information that S4 active RFID tag receives module for reading and writing transmission represents that label information sends successfully, and stop sending anticollision For Spread Spectrum Sequences information；Otherwise enter step S5；
S5, utilize dynamic slot ALOHA algorithm, quantity according to empty slot, correct read-write time slot and collision time slot calculates the active RFID tag number needing read-write in the next time period, number of time slots in the distribution next time period, launches the label collided different time-gap within the next time period.
Further, described wake-up signal is that wake module wakes For Spread Spectrum Sequences up by what signal specific employing Direct Sequence Spread Spectrum Communication technology was completed, and active RFID tag wakes frequency expansion sequence up by de-spreading reception.
Further, different active RFID tags moment difference of reviving after periodic sleep state.
Further, the anticollision For Spread Spectrum Sequences that all radio-frequency modules in described module for reading and writing that prestored in described active RFID tag are able to receive that, described active RFID tag obtains the radio-frequency module information used in module for reading and writing according to the information in wake-up signal, and the anticollision For Spread Spectrum Sequences being able to receive that further according to radio-frequency module selects corresponding anticollision For Spread Spectrum Sequences to send to module for reading and writing.
Further, described step S5 adopts hash function distribution number of time slots, the formula of described hash function is: hash (i+1)=hash (i) < < 5+hash (i)+ID (i), (0≤i≤m), H=hash (m) %P；Wherein: the initial value of hash (0) selects a undistinguishable prime number, and ID represents the unique identifier of active RFID tag, ID (i) represents the not coordination of ID；M is No. ID of the active RFID tag represented with how many bits, and P is the prime number of the label number needing read-write in subsequent time period；In described formula H=hash (m) %P, what H calculated is the cryptographic Hash that calculates of the first step remainder divided by P, arranges label to launch at certain time slot according to the H-number calculated.
Further, if the result that different active RFID tags calculates according to Hash formula is consistent, then in next step calculates, change P value.
In order to solve technical problem, present invention also offers the active RFID reader collision avoidance system based on multi-radio, including reader and active RFID tag, described reader includes wake module and module for reading and writing, and module for reading and writing includes at least two radio-frequency module；Wherein, described wake module is for sending wake-up signal to the active RFID tag in reader coverage；Each radio-frequency module in described module for reading and writing is able to receive that a kind of anticollision For Spread Spectrum Sequences, after described radio-frequency module receives the corresponding anticollision For Spread Spectrum Sequences that active RFID tag sends, then sends ACK acknowledgement information to active RFID tag；Described active RFID tag for monitoring ambient signals through periodic sleep state immediately after reviving, if listening to the wake-up signal that wake module sends, then send anticollision For Spread Spectrum Sequences signal to the module for reading and writing in reader, otherwise label is again introduced into periodic sleep state, and according to whether receive the ACK acknowledgement information that module for reading and writing sends to judge whether again to send anticollision For Spread Spectrum Sequences to reader.
Further, different active RFID tags moment difference of reviving after periodic sleep state.
Further, the anticollision For Spread Spectrum Sequences that all radio-frequency modules in described module for reading and writing that prestored in described active RFID tag are able to receive that, described active RFID tag obtains the radio-frequency module information used in module for reading and writing according to the information in wake-up signal, and the anticollision For Spread Spectrum Sequences being able to receive that further according to radio-frequency module selects corresponding anticollision For Spread Spectrum Sequences to send to module for reading and writing.
Beneficial effects of the present invention: the present invention passes through the advantage in conjunction with code division technology, time division technique and dynamic slot ALOHA algorithm based on active RFID reader collision-proof method and the system of multi-radio, improve treatment effeciency and the processing speed of electronic tag, and by adopting direct spreading sequence technical communication, improve the safety and reliability of system work and anticollision performance.
Accompanying drawing explanation
Fig. 1 is the embodiment of the present invention FB(flow block) based on the active RFID reader collision-proof method of multi-radio；
Fig. 2 is the embodiment of the present invention structured flowchart based on the active RFID reader collision avoidance system of multi-radio；
Fig. 3 is the embodiment of the present invention work sheet based on the active RFID reader collision avoidance system of multi-radio；
Fig. 4 is that the embodiment of the present invention is based on label anti-collision figure in the active RFID reader collision-proof method of multi-radio；
Fig. 5 is that the embodiment of the present invention is based on label collision rift process figure in the active RFID reader collision-proof method of multi-radio.
Detailed description of the invention
Below in conjunction with accompanying drawing and specific embodiment, the invention will be further elaborated.
It is illustrated in figure 1 the embodiment of the present invention FB(flow block) based on the active RFID reader collision-proof method of multi-radio, specifically includes:
Wake module in S1, reader sends wake-up signal to the active RFID tag in reader coverage；
S2, active RFID tag monitor ambient signals through periodic sleep state immediately after reviving, if listening to the wake-up signal that wake module sends, then use anticollision For Spread Spectrum Sequences to send signal to the module for reading and writing in reader；Otherwise label is again introduced into periodic sleep state；
There is multiple radio-frequency module in S3, module for reading and writing, each radio-frequency module is able to receive that a kind of anticollision For Spread Spectrum Sequences, after radio-frequency module receives corresponding anticollision For Spread Spectrum Sequences information, then sends ACK acknowledgement information to active RFID tag；
If the ACK acknowledgement information that S4 active RFID tag receives module for reading and writing transmission represents that label information sends successfully, and stop sending anticollision For Spread Spectrum Sequences information；Otherwise enter step S5；
S5, utilize dynamic slot ALOHA algorithm, quantity according to empty slot, correct read-write time slot and collision time slot calculates the active RFID tag number needing read-write in the next time period, number of time slots in the distribution next time period, launches the label collided different time-gap within the next time period.
Based on said method, present invention also offers the active RFID reader collision avoidance system based on multi-radio, as in figure 2 it is shown, include reader and active RFID tag, described reader includes wake module and module for reading and writing, and module for reading and writing includes at least two radio-frequency module；Wherein, described wake module is for sending wake-up signal to the active RFID tag in reader coverage；Each radio-frequency module in described module for reading and writing is able to receive that a kind of anticollision For Spread Spectrum Sequences, after described radio-frequency module receives the corresponding anticollision For Spread Spectrum Sequences that active RFID tag sends, then sends ACK acknowledgement information to active RFID tag；Described active RFID tag for monitoring ambient signals through periodic sleep state immediately after reviving, if listening to the wake-up signal that wake module sends, then send anticollision For Spread Spectrum Sequences signal to the module for reading and writing in reader, otherwise label is again introduced into periodic sleep state, and according to whether receive the ACK acknowledgement information that module for reading and writing sends to judge whether again to send anticollision For Spread Spectrum Sequences to reader.
Following for skilled artisans appreciate that and implementing technical solution of the present invention, the method for the invention and system will be described in detail:
The reader of the present invention includes wake module and module for reading and writing, wherein module for reading and writing needs to accept from the data message of label and it is processed, wake module needs constantly to launch wake-up signal, label receives the moment of wake-up signal, send signal with anticollision code to reader immediately according to the information in wake-up signal, within the regular hour, wait, sending, the ACK acknowledgement information that reader is replied after signal completes；Reader, after receiving the information that label anticollision code sends, returns ACK receipt to label immediately.Label performs next step action according to the acknowledgement information of ACK, will be considered to send success and stop sending if receiving ACK acknowledgement information label, performing action set in advance over time.If during this period of time not receiving ack signal, label then arranges to resend；In order to be effectively prevented from having occurred and that the label of collision continues when resending to collide with those, arrange label delay within the next time period to send, be so repeated up to label and receive ACK or exceed maximum number of times of transmission set in advance.
The present invention is in order to be effectively prevented from having occurred and that the label of collision continues when resending to collide with those, utilize dynamic slot ALOHA algorithm, different with the quantity of collision time slot according to empty slot, correctly read-write time slot, the general label number estimating to need read-write in the next time period, then the number of time slot in the distribution next time period, arranges the label collided different time-gap within the next time period to launch.Number of time slots is typically chosen the less prime number of the label number needing read-write in the subsequent time period of estimation, utilize hash function distribution time slot, simply and uniformly distribute Slot format label to launch with collision free, the formula of described hash function is: hash (i+1)=hash (i) < < 5+hash (i)+ID (i), 0≤i≤m；H=hash(m)%P；Wherein: the initial value of hash (0) selects a undistinguishable prime number, ID represents the unique identifier of label, ID (i) represents the not coordination of ID, m represents and represents that tag ID number, P are typically chosen the less prime number of label number needing read-write in the subsequent time period of estimation with how many bits.What in formula H=hash (m) %P, H calculated is the cryptographic Hash that calculates of the first step remainder divided by P, arranges label to launch at certain time slot according to the H-number calculated.If different labels calculates result, consistent label will select identical time slot, thus colliding, then can change the value of P in next step calculates, choose close to that the bigger prime number estimating to need the label number of read-write, so the label of collision is at different slot transmission, it is to avoid again collide.
The present invention is for improving anti-collision simultaneously, the moment that different labels is revived is inconsistent, now largely just distinguish most of label in time, without etc. all labels wake up after send information to reader at the same time, to a great extent it is avoided that there is large-scale collision in this.Active RFID tag only one of which radio receiving transmitting module, but its communication channel and For Spread Spectrum Sequences switching able to programme；The corresponding anticollision code of each radio-frequency module in module for reading and writing, the anticollision code that the some groups of module for reading and writing that can prestore in the label use, receive at label and contain which module for reading and writing reader uses in the information of wake command, label then selects one group in these corresponding several groups of anticollision codes, then sends radiofrequency signal with this group anticollision code and communicates to reader.
For the label revived simultaneously, randomly choosing different preventing collision code and send label information to reader, reader receives the information of different anticollision codes according to different radio-frequency modules, distinguishes label with this and prevents collision.Below in conjunction with concrete situation illustrates how to improve anticollision performance according to method and system of the present invention:
As shown in Figure 3, for instance radio-frequency module has three, then correspondence uses three independent anticollision code PN1, PN2 and PN3, then label enters row stochastic selection at these three groups of anticollision codes, selects one group of anticollision code, then sends radiofrequency signal with this group anticollision code and communicates to reader.As shown in Figure 4, most label is revived moment difference, after reviving, launches information to reader at once, this just natural can anticollision.If label is revived simultaneously, according to randomly choosing different PN codes, different radio-frequency modules receives different label informations, if label 1 and label 2 are revived simultaneously, but they communicate with different PN codes and reader, so without collision between them；If label 1 and label 3, although PN code-phase with, but their moment difference of reviving, so they are without colliding.
If as it is shown in figure 5, the label 1,2 and 3 revived simultaneously, going out again to select same anticollision code PN1 to send information at random, then now these labels can collide naturally；According to dynamic slot ALOHA algorithm, these labels collided are arranged in reviving in the next time period, and the moment revived sends information to reader, and one group of anticollision code of selection random after waking up is transmitted information；If if label 1 and label 2 are again revive simultaneously, if the PN code difference at this moment gone out at random, do not collide；And between label 1,2 and label 3, it is likely to difference according to the time slot that hash algorithm value of calculation is revived, then without colliding between them.
Those of ordinary skill in the art is it will be appreciated that embodiment described here is to aid in reader understanding's principles of the invention, it should be understood that the protection domain of invention is not limited to such special statement and embodiment.Every make various possible equivalent replacement or change according to foregoing description, be all considered to belong to the scope of the claims of the present invention.
Claims (5)
1. based on the active RFID reader collision-proof method of multi-radio, it is characterised in that specifically include:
Wake module in S1, reader sends wake-up signal to the active RFID tag in reader coverage；
S2, active RFID tag monitor ambient signals through periodic sleep state immediately after reviving, if listening to the wake-up signal that wake module sends, then use anticollision For Spread Spectrum Sequences to send signal to the module for reading and writing in reader；Otherwise label is again introduced into periodic sleep state；
There is multiple radio-frequency module in S3, module for reading and writing, each radio-frequency module is able to receive that a kind of anticollision For Spread Spectrum Sequences, after radio-frequency module receives corresponding anticollision For Spread Spectrum Sequences information, then sends ACK acknowledgement information to active RFID tag；
If the ACK acknowledgement information that S4 active RFID tag receives module for reading and writing transmission represents that label information sends successfully, and stop sending anticollision For Spread Spectrum Sequences information；Otherwise enter step S5；
S5, utilize dynamic slot ALOHA algorithm, quantity according to empty slot, correct read-write time slot and collision time slot calculates the active RFID tag number needing read-write in the next time period, adopt the number of time slots in the hash function distribution next time period, the label collided different time-gap within the next time period is launched, the formula of described hash function is: hash (i+1)=hash (i) < < 5+hash (i)+ID (i), (0≤i≤m), H=hash (m) %P；Wherein: the initial value of hash (0) selects a undistinguishable prime number, and ID represents the unique identifier of active RFID tag, ID (i) represents the not coordination of ID；M is No. ID of the active RFID tag represented with how many bits, and P is the prime number of the label number needing read-write in subsequent time period；In described formula H=hash (m) %P, what H calculated is the cryptographic Hash that calculates of the first step remainder divided by P, label is arranged to launch at certain time slot according to the H-number calculated, if the result that different active RFID tags calculates according to Hash formula is consistent, then in next step calculates, change P value.
2. the active RFID reader collision-proof method based on multi-radio as claimed in claim 1, it is characterised in that different active RFID tags moment difference of reviving after periodic sleep state.
3. the active RFID reader collision-proof method based on multi-radio as claimed in claim 1, it is characterized in that, the anticollision For Spread Spectrum Sequences that all radio-frequency modules in described module for reading and writing that prestored in described active RFID tag are able to receive that, described active RFID tag obtains the radio-frequency module information used in module for reading and writing according to the information in wake-up signal, and the anticollision For Spread Spectrum Sequences being able to receive that further according to radio-frequency module selects corresponding anticollision For Spread Spectrum Sequences to send to module for reading and writing.
4. based on the active RFID reader collision avoidance system of multi-radio, it is characterised in that including reader and active RFID tag, described reader includes wake module and module for reading and writing, and module for reading and writing includes at least two radio-frequency module；Wherein, described wake module is for sending wake-up signal to the active RFID tag in reader coverage；Each radio-frequency module in described module for reading and writing is able to receive that a kind of anticollision For Spread Spectrum Sequences, after described radio-frequency module receives the corresponding anticollision For Spread Spectrum Sequences that active RFID tag sends, then sends ACK acknowledgement information to active RFID tag；Described active RFID tag for monitoring ambient signals through periodic sleep state immediately after reviving, if listening to the wake-up signal that wake module sends, then send anticollision For Spread Spectrum Sequences signal to the module for reading and writing in reader, otherwise label is again introduced into periodic sleep state, and according to whether receive the ACK acknowledgement information that module for reading and writing sends to judge whether again to send anticollision For Spread Spectrum Sequences to reader；The anticollision For Spread Spectrum Sequences information that all radio-frequency modules in described module for reading and writing that prestored in described active RFID tag are able to receive that, described active RFID tag obtains the radio-frequency module information used in module for reading and writing according to the information in wake-up signal, and the anticollision For Spread Spectrum Sequences being able to receive that further according to radio-frequency module selects corresponding anticollision For Spread Spectrum Sequences to send to module for reading and writing.
5. the active RFID reader collision avoidance system based on multi-radio as claimed in claim 4, it is characterised in that different active RFID tags moment difference of reviving after periodic sleep state.
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| CN105810130A (en) * | 2014-12-31 | 2016-07-27 | 航天信息股份有限公司 | Scenic area guided tour system and method |
| CN105205425B (en) * | 2015-11-02 | 2017-12-26 | 浪潮(北京)电子信息产业有限公司 | A kind of RFID anti-collision method based on multiway tree |
| TWI638315B (en) * | 2017-05-03 | 2018-10-11 | 九齊科技股份有限公司 | Method and device for transmission of radio-frequency signal |
| CN107766764A (en) * | 2017-10-30 | 2018-03-06 | 上海华虹集成电路有限责任公司 | A kind of collision-proof method of 2.4G active electronic labels |
| CN109598168A (en) * | 2018-12-21 | 2019-04-09 | 大连大学 | Radio frequency identification anti-collision algorithm and system based on chaotic maps |
| CN110969036B (en) * | 2019-11-25 | 2021-04-30 | 独角兽网络科技（苏州）有限公司 | Method, device, equipment and storage medium for RFID label data output |
| CN111414775B (en) * | 2020-02-20 | 2021-10-15 | 北京邮电大学 | Multi-reader anti-collision method, device and equipment for RFID label access |
| TWI755138B (en) * | 2020-11-02 | 2022-02-11 | 凌通科技股份有限公司 | Radio frequency identification communication method for collision reduction with low power consumption and radio frequency identification communication system using the same |
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| CN101281587B (en) * | 2007-07-26 | 2010-06-09 | 北京航空航天大学 | Radio frequency recognition reading method and answering method |
| CN101359361A (en) * | 2008-09-17 | 2009-02-04 | 湖南大学 | Data anticollision algorithm in RFID system |
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