CN104156680A - UHF RFID reader based on beam switching smart antenna - Google Patents
UHF RFID reader based on beam switching smart antenna Download PDFInfo
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- CN104156680A CN104156680A CN201410355717.8A CN201410355717A CN104156680A CN 104156680 A CN104156680 A CN 104156680A CN 201410355717 A CN201410355717 A CN 201410355717A CN 104156680 A CN104156680 A CN 104156680A
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Abstract
The invention discloses a UHF RFID reader based on a beam switching smart antenna and belongs to the technical field of radio frequency identification. The UHF RFID reader is characterized in that during signal transmitting, a digital module controls a radio-frequency transceiver module to produce a radio frequency signal according to commands and communication protocol of a controller, meanwhile, the digital module controls a beam change-over switch to switch corresponding channels of a beam former according to the beam switching control algorithm, the radio frequency signal generates an output signal of which the phase difference conforms to a certain rule after passing through the beam former, and the output signal is amplified by a power amplifier and then fed into an antenna array through a transmit-receive duplexer. The gains of all power amplifiers are controlled by the digital module. Electromagnetic waves radiated by antenna array elements are stacked in the space to form a high-gain narrow beam. During signal receiving, the process is opposite to that during signal transmitting. According to the invention, the maximal read-write distance, the effective recognition zone, the collision resistance, the positioning accuracy and the like are all improved.
Description
Technical field
The present invention relates to a kind of radio-frequency (RF) identification (RFID) technology, particularly a kind of UHF RFID reader
Background technology
Along with the development of infotech, Internet of Things has developed into a new industry, and as one of basis of Internet of Things, radio-frequency (RF) identification (RFID, Radio Frequency Identification) technology has become the technology that people more and more pay close attention to.Rfid system is mainly comprised of three parts: transponder (radio-frequency card and electronic tag), reader (read write line and base station) and host computer main system (middleware and network application).In radio-frequency recognition system, according to the different structure of electronic tag electric power system, RFID electronic tag is mainly divided into active label, semi-active label and passive label.Active label and semi-active label have external battery, and the work that is label chip by external battery provides energy, and its advantage is to have communication distance far away, can increase more circuit and function strong; Shortcoming is that price is high, and volume is large, and be restricted the serviceable life of label, and along with the consumption of battery electric power in label, the distance of data transmission can be more and more less, affects the normal work of system.Passive label relies on the radiofrequency signal of reader to provide energy to make its work, has the advantages such as volume is little, cost is low, the life-span is long, non-maintaining, easy to use, is the main product of RFID label.
At present, there is following problem in passive UHF rfid system:
(1) in passive UHF rfid system, the maximum decipherment distance of a reader is 10 meters of left and right, and total effective identified region is limited, can't meet most of users' demand.
(2), in passive UHF rfid system, a crucial problem is to be difficult to reach 100% discrimination, exists some labels not to be identified, and loses label problem.From hardware aspect, the problem of losing label has two main causes: first, because the transmission power limit of antenna and fixing antenna pattern, so effective identified region of passive RFID system is limited.The second, multipath disturbs and causes some labels in identified region not have enough energy to be activated.
(3) many labels are received the RF signal from single reader.In effective identified region of this reader, label is shared same wireless channel, due to interfering with each other between the scattered signal of a plurality of labels, thereby causes collision.The quantity of collision has a great impact for total recognition time of all labels in identified region.In order to reduce or to avoid collision, rfid system has been taked anticollision measure on software, such as binary tree, ALOHA etc.But the anticollision that relies on merely software to realize, is difficult to realize efficient result, if there has been the support from antenna aspect, can make anticollision more effective.
(4) due to conventional RFID reader antenna, there is the transmitting pattern of low gain, broad beam, make tag location error larger.
Smart antenna is exactly to utilize the combination of a plurality of bays to carry out signal processing, automatically adjusts and transmits and receives directional diagram, reaches the antenna of best performance with the signal environment for different.Initial intelligent antenna technology is mainly used in radar, sonar, military antijam communication, has been used for spatial filtering and location etc.Now, smart antenna application is extensive, it improving system communication quality, alleviate radio communication growing contradiction and reduction entire system cost with frequency spectrum resource deficiency and improve the aspects such as system management, it is unique all to have advantages of.
In passive UHF RFID reader, use smart antenna to contribute to solve current problem and improving performance, be in particular in the following aspects:
(1) utilize digital multi-beam scanning can increase maximum decipherment distance and effective identified region of rfid system.At passive UHF rfid system, maximum decipherment distance is limited to the minimal detectable power P that activates label chip
th.The computing formula of maximum decipherment distance is
Wherein, λ is operation wavelength, P
tthe emissive power of reader, G
tthe gain of reader antenna, P
tg
tequivalent isotropically radiated power (EIRP), G
rbe the gain of label antenna, p is that (polarization is when mate completely, and p=1), τ is the power delivery factor (during conjugate impedance coupling, τ=1) of label antenna and label chip for the polarization match factor of reader antenna and label antenna.The reader antenna radiation EIRP maximal value of every country defined is limited, and for example the maximal value of the regulation EIRP of FCC (FCC) is 4W.If use the phased array antenna that can produce a plurality of high-gain wave beams, EIRP can surpass 4W in certain direction within some short time, when calculating average power, it has and low directivity, average power that fixed beam antenna is identical, because wave beam is scanned control in multiple directions, thereby reduced average power.In normal work, wave beam was measured and is scanned in multiple directions with predetermined time, and therefore maximum decipherment distance is along with EIRP (P
tg
t) increase and increased.Because wave beam scans in multiple directions, so total identified region has also been expanded.
(2) utilize the space division multiple access technique (SDMA) of smart antenna, spatial filtering function, can reduce or avoid collision.Reader, by controlling beam direction, is selected a subset of effective identified region, thus only with this subset area in label communication.Because respond the number of tags of RFID order simultaneously, reduced, so the probability of collision also just reduces, in whole identified region, total recognition time of all labels can shorten.In addition, the spatial filtering function of smart antenna can reduce multipath effectively to be disturbed, and improves tag recognition rate.
(3) high directionality of smart antenna, less beam saltus (variable quantity when controlling antenna wave beam to point angle changes) and higher angular resolution can improve the precision of RFID location.
Summary of the invention
Object of the present invention is exactly in order to solve above-mentioned the deficiencies in the prior art part, proposes a kind of UHF RFID reader based on wave beam switch type smart antenna.Under emission state, adopt simulation multi-beam formation method: the narrow beam that forms a high-gain at synchronization, then between a plurality of wave beams, switch in order in time, by " time division " principle, produce multi-beam, thus the scanning overlay area of wanting.Wave beam switching controls algorithm can be according to scanning sequency, residence time and the sweep interval etc. of the situation switching-beams such as the number of tags of all directions, call duration time.
For achieving the above object, now design a kind of UHF RFID reader based on wave beam switch type smart antenna, comprise controller MCU, digital module, radio-frequency (RF) receiving and transmission module, wave beam change-over switch, Beam-former, gain program controlled power amplifier PA, low noise amplifier LNA, duplexer DUP and aerial array.It is characterized in that, during transmitted signal, digital module is controlled radio-frequency (RF) receiving and transmission module generation radiofrequency signal according to the instruction of controller and communication protocol, digital module is controlled the respective channel of wave beam change-over switch switching-beam shaper according to wave beam switching controls algorithm simultaneously, this radiofrequency signal produces the output signal that phase differential meets certain rule after by Beam-former, then after being amplified by power amplifier by duplexer feed antenna array.The gain of each power amplifier is controlled by digital module.After superposeing in space, the electromagnetic wave of each bay radiation forms the narrow beam of a high-gain.While receiving signal, contrary with the process of transmitted signal, the signal that aerial array receives enters receiving cable through duplexer, after being amplified, through Beam-former, wave beam change-over switch, radio-frequency (RF) receiving and transmission module, to digital module, processes by low noise amplifier.
Described wave beam change-over switch is single-ended-multiterminal radio-frequency (RF) switch, is a kind of input and output invertible switch.The multiport of described wave beam change-over switch is connected with Beam-former, and single port is connected with receiving port with the radio-frequency transmissions port of radio-frequency (RF) receiving and transmission module respectively with receiving cable at transmission channel.
Described Beam-former is many inputs, many output networks, is reciprocal device.
Described power amplifier is the program-controlled high power amplifier of gain.
The present invention has the following advantages with respect to prior art: this read-write system can make aerial radiation direction switch between a plurality of wave beams, according to situations such as the number of tags of all directions, call duration times, control scanning sequency, residence time and the sweep interval of wave beam, the abilities such as the maximum reading/writing distance of reader, effective identified region, anticollision and positioning precision are improved.
Accompanying drawing explanation
In order to be illustrated more clearly in inventive embodiments or technical scheme of the prior art, to the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skills, do not paying under the prerequisite of creating work, can also obtain with reference to the accompanying drawings other accompanying drawing.
The UHF RFID reader schematic diagram of Fig. 1 based on wave beam switch type smart antenna.
Embodiment
For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing, embodiment of the present invention is described further in detail, but embodiments of the present invention are not limited to this.
As shown in Figure 1, take and form 4 fixed beams as the UHF RFID reader of example explanation based on wave beam switch type smart antenna.The present invention includes controller MCU, digital module, radio-frequency (RF) receiving and transmission module, wave beam change-over switch, Beam-former, gain program controlled power amplifier PA, low noise amplifier LNA, duplexer DUP and aerial array.
While transmitting, digital module is controlled radio-frequency (RF) receiving and transmission module generation radiofrequency signal according to the instruction of controller and communication protocol, digital module passes through wave beam change-over switch gating A according to wave beam switching controls algorithm simultaneously, B, C, D Zhong mono-tunnel, the signal that radio-frequency (RF) receiving and transmission module is sent is entered after Beam-former by a passage, form the new signal of four tunnel outs of phase, the new signal in Zhe Si road is connected respectively to four bays after power amplifier and duplexer, by these four bay transmission of electromagnetic signals, and in space, form a corresponding high-gain narrow beam.Such as the corresponding wave beam A1 in A road, transmit and only arrive the space that A1 wave beam covers.The corresponding wave beam B1 in B road, transmits and only arrives the space that B1 wave beam covers.The corresponding wave beam C1 in C road, transmits and only arrives the space that C1 wave beam covers.The corresponding wave beam D1 in D road, transmits and only arrives the space that D1 wave beam covers.
While receiving signal, with transmit on the contrary, the received electromagnetic signal of certain wave beam is broken down into 4 bays, forms 4 road signals, after amplifying by low noise amplifier, in Beam-former, according to the synthetic road signal of phase differential, by wave beam change-over switch, selecting this road signal to output to the receiving end of radio-frequency (RF) receiving and transmission module, is still finally the corresponding road signal of a wave beam in space, such as wave beam A1 corresponding A 2 tunnels, the corresponding B2 of wave beam B1 road, the corresponding C2 of wave beam C1 road, the corresponding D2 of wave beam D1 road.The corresponding signal of beam coverage area while finally selecting transmitting by wave beam change-over switch, for example, during transmitting, wave beam change-over switch is selected A road corresponding wave beam A1, and while receiving, wave beam change-over switch is selected the corresponding A2 of wave beam A1 road signal.Then, this signal is delivered to digital module and is for further processing.
Further, in order to obtain higher wave beam resolving power, need fixed beam and the passage of greater number, during specific implementation, the embodiment of the present invention is not restricted this.
Further, wave beam change-over switch has multiple implementation, and during specific implementation, the embodiment of the present invention is not restricted this.
Further, Beam-former has multiple implementation, and during specific implementation, the embodiment of the present invention is not restricted this.
Further, aerial array has the multiple implementations such as linear array, face battle array, and during specific implementation, the embodiment of the present invention is not restricted this.
During specific implementation, the embodiment of the present invention does not limit realizing the selected chip kind of identity function.
It will be appreciated by those skilled in the art that accompanying drawing is the schematic diagram of a preferential embodiment, the invention described above embodiment sequence number, just to describing, does not represent the quality of embodiment.
Above-described embodiment is preferably embodiment of the present invention; but embodiments of the present invention are not restricted to the described embodiments; other any do not deviate from change, the modification done under Spirit Essence of the present invention and principle, substitutes, combination, simplify; all should be equivalent substitute mode, within being included in protection scope of the present invention.
Claims (3)
1. the UHF RFID reader based on wave beam switch type smart antenna, comprises controller MCU, digital module, radio-frequency (RF) receiving and transmission module, wave beam change-over switch, Beam-former, gain program controlled power amplifier PA, low noise amplifier LNA, duplexer DUP and aerial array; It is characterized in that: during transmitted signal, digital module is controlled radio-frequency (RF) receiving and transmission module generation radiofrequency signal according to the instruction of controller and communication protocol, digital module is controlled the respective channel of wave beam change-over switch switching-beam shaper according to wave beam switching controls algorithm simultaneously, this radiofrequency signal produces the output signal that phase differential meets certain rule after by Beam-former, then after being amplified by power amplifier by duplexer feed antenna array.The gain of each power amplifier is controlled by digital module.After superposeing in space, the electromagnetic wave of each bay radiation forms the narrow beam of a high-gain.While receiving signal, contrary with the process of transmitted signal, the signal that aerial array receives enters receiving cable through duplexer, after being amplified, through Beam-former, wave beam change-over switch, radio-frequency (RF) receiving and transmission module, to digital module, processes by low noise amplifier.
2. a kind of UHF RFID reader based on wave beam switch type smart antenna as claimed in claim 1, is characterized in that: described wave beam change-over switch is single-ended-multiterminal radio-frequency (RF) switch, is a kind of input and output invertible switch.The multiport of described wave beam change-over switch is connected with Beam-former, and single port is connected with receiving port with the emission port of radio-frequency (RF) receiving and transmission module respectively with receiving cable at transmission channel.
3. a kind of UHF RFID reader based on wave beam switch type smart antenna as claimed in claim 1, is characterized in that: described Beam-former, for many inputs, many output networks, is reciprocal device.
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| CN201410355717.8A CN104156680A (en) | 2014-07-21 | 2014-07-21 | UHF RFID reader based on beam switching smart antenna |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106127091A (en) * | 2016-06-30 | 2016-11-16 | 天津工业大学 | A kind of intelligent UHFRFID reader based on DSP |
| CN106169026A (en) * | 2016-06-30 | 2016-11-30 | 天津工业大学 | A kind of intelligence switching-beam algorithm |
| CN106991740A (en) * | 2017-01-19 | 2017-07-28 | 北京大学 | A kind of method for entering and exiting management and intelligent wireless RFID card reader device |
| CN113420573A (en) * | 2020-09-23 | 2021-09-21 | 阿里巴巴集团控股有限公司 | Phased array system and phase setting method |
-
2014
- 2014-07-21 CN CN201410355717.8A patent/CN104156680A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106127091A (en) * | 2016-06-30 | 2016-11-16 | 天津工业大学 | A kind of intelligent UHFRFID reader based on DSP |
| CN106169026A (en) * | 2016-06-30 | 2016-11-30 | 天津工业大学 | A kind of intelligence switching-beam algorithm |
| CN106169026B (en) * | 2016-06-30 | 2018-12-07 | 天津工业大学 | A kind of intelligence switching-beam algorithm |
| CN106991740A (en) * | 2017-01-19 | 2017-07-28 | 北京大学 | A kind of method for entering and exiting management and intelligent wireless RFID card reader device |
| CN113420573A (en) * | 2020-09-23 | 2021-09-21 | 阿里巴巴集团控股有限公司 | Phased array system and phase setting method |
| CN113420573B (en) * | 2020-09-23 | 2023-12-15 | 阿里巴巴集团控股有限公司 | Phased array system and phase setting method |
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Application publication date: 20141119 |