CN102904638A - LED (light-emitting diode)-based indoor wireless optical communication OCDMA (Optical Code Division Multiple Access) upstream communication system - Google Patents
LED (light-emitting diode)-based indoor wireless optical communication OCDMA (Optical Code Division Multiple Access) upstream communication system Download PDFInfo
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- CN102904638A CN102904638A CN2012104057635A CN201210405763A CN102904638A CN 102904638 A CN102904638 A CN 102904638A CN 2012104057635 A CN2012104057635 A CN 2012104057635A CN 201210405763 A CN201210405763 A CN 201210405763A CN 102904638 A CN102904638 A CN 102904638A
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Abstract
The invention relates to an LED (light-emitting diode)-based indoor wireless optical communication OCDMA (Optical Code Division Multiple Access) upstream communication system, which belongs to the field of indoor wireless optical communication, and in particular relates to an OCDMA upstream communication in wireless optical communication. Under the situation that the indoor illuminance requirement is met, downstream communication is achieved indoors; and simultaneously, a three-primary-color LED is taken as the basis, the terminal can modulate pre-send information into digital pulse which is sent to a receiving base station of a ceiling through the LED, different orthogonal address codes can be used for distinguishing by each user, and the base station demodulates an optical signal into a digital signal after receiving the optical signal, distinguishes the information sent by the user, and transmits the information to an external network, so as to achieve the upstream communication of the terminal.
Description
Technical field
The invention belongs to the indoor wireless optical communication field, specifically relate to the OCDMA uplink communication in the wireless light communication.（H04B?7/17、?H04B7/216、?H04B?10/10、?H04B?10/10）。
Background technology
Indoor wireless optical communication is a kind of indoor advanced communication system take the LED illuminating lamp as signal emitting-source, for indoor wireless equipment provides access, system adopt carrier modulation with signal loading on power line, being transformed into direct current signal after the filtered device of LED lamp front end leaches is loaded on the LED lamp, height according to electric current, the LED lamp sends light signal, signal have have by force a little less than.Because strong and weak variation is very fast, has surpassed the sensitivity of naked eyes, the imperceptible flicker of people.The light that LED sends arrives the desktop terminal receiver after interior space transmission, the receiving chip of receiver is transformed into the signal of telecommunication with light signal, then adjudicates, and recovers digital signal and passes to terminal, realized that from physical layer signal is transmitted into a downlink communication of reception
Up to now, the visible light receive mode mainly is descending, and terminal can receive the information of system and can not send information, and the signal pulse that receiver sends the LED lamp is surveyed reception, then carries out demodulation and obtains digital signal and pass to terminal equipment
[1-2]System mainly is comprised of LED illuminating lamp, optically filtering receiver, photodetector, converts the electrical signal to light signal and is emitted by the LED lamp afterwards, is received demodulation at receiving terminal behind indoor free-space propagation.But the weak point that exists is: the communication mode that system realizes is single file communication, terminal can only be from the signal of LED illuminating lamp obtaining information and can not upload information.Can not satisfy the demand of the two-way communication of common equipment, so-called two-way communication is that terminal can be passed through Network Capture information, also the information exchange of oneself can be crossed the base station and send on the network.
Documents
[1]?Toshihiko?Komine,?Masao?Nakagawa.?Fundamental?Analysis?for?Visible-Light?Communication?System?using?LED?Lights[C].?IEEE?Transactions?on?Consumer?Electronics.?Feb.,?2004,?50(1):100-107.
[2]?Yuichi?Tanaka,?Toshihiko?Komine.?Indoor?Visible?Light?Data?Transmission?System?Utilizing?White?LED?Lights[C].?IEICE?Trans.?Commun.,Aug,2003,?E86-B(8):2440-2454.
Summary of the invention
The technical problem that 1, will solve (i.e. former " goal of the invention ")
In the situation that satisfy the requirement of room lighting degree, at indoor realization downlink communication; Simultaneously take three-primary color LED as the basis, terminal can be modulated into digit pulse with in advance transmission information, send to the reception base station of ceiling by LED, each user with different quadrature address codes to show difference, after base station receiver receives light signal, light signal is demodulated to digital signal, identification is the information which user sends, and information is sent to external network, realize the uplink communication of terminal.
2, technical scheme (method invention)
The present invention is that the technical scheme that its technical problem of solution adopts is:
1) terminal signaling converts the LED light signal to:
Method is described: modulator is modulated the pre-signal that sends of user terminal, and then the orthogonal code with the expression user multiplies each other, and signal code is driven the chip light emitting of three kinds of colors of three-primary color LED, and the light of three kinds of colors mixes and remains white light.
2) filtering and opto-electronic conversion:
Signal is sent by the LED of terminal equipment, and the filter plate of base station receiver front end can separate white light, other two kinds of light of filtering.It is corresponding that the used filter plate of base station receiver and the flashlight of three-primary color LED are thought, the ruddiness filter plate can the filtering blue light and green glow see through red signal light; The green glow filter plate can see through green optical signal by the filtering Red and blue light; The blue light filter plate can filtering ruddiness and green glow see through the blue light signal.The optical-electrical converter of filter plate back converts light signal to electric current, carries out integration, then output electrical signals within the time of a chip.
3) data are recovered:
Signal recovery device after filter plate as shown in Figure 7, the signal of telecommunication that receives and each user's address code are multiplied each other, then convert Serial No. to by judgment device, and the Serial No. that judgement obtains is carried out demodulation, recover the signal that user terminal sends.
3, beneficial effect
The present invention adopts the OCDMA technology, orthogonal code and the end message of identifying user address are multiplied each other, luminous by the terminal signaling driving LED, terminal signaling is sent to the ceiling base station, and the information that receives is recovered in the base station, the information that each different terminals of sub-department sends, and arrive outside by Internet Transmission, realize communicating by letter of terminal and external network, solved terminal and can only receive the problem that information can not send information, realized real two-way communication.
Accompanying drawing and subordinate list explanation
Fig. 1 indoor wireless up link schematic diagram.
Fig. 2 indoor wireless uplink communication block diagram.
Fig. 3 final drive LED sends light signal.
Fig. 4 serial to parallel conversion schematic diagram.
Fig. 5 receives light filtering and the opto-electronic conversion of base station.
Fig. 6 parallel-serial conversion schematic diagram.
Fig. 7 recovers the base station to the received signal.
Embodiment
Indoor wireless uplink communication schematic diagram as shown in Figure 1, the structured flowchart of simplification as shown in Figure 2, system mainly is comprised of terminal, modulating equipment, quadrature address code, LED, photoelectricity receiving converter, demodulator etc.The signal that terminal will send in advance is transferred to modulator, modulator with the signal that receives according to certain modulation system, be modulated into Serial No. such as OOK, PPM, MPPM etc., then the orthogonal code with the unique identification terminal address multiplies each other, obtain new sequence, by high-low level driving LED transmitted signal.The string of LED front end and conversion equipment convert the serial signal that receives to parallel signal, distribute to respectively three different chips of three-primary color LED, make three chips luminous or not luminous according to the high-low level of input.The LED sender unit of terminal has very little lighting angle, the signal receiving device on the light aiming ceiling.
Flashlight is propagated in the interior space after being sent by LED, separated after receiving by the receiving system on the ceiling, white light is separated into three kinds of colors of RGB by the filter plate of three primary colors, each filter plate can only see through the flashlight of certain solid color, after receiving, the photoelectric detector of filtered back of flashlight converts electric current to, integrator carries out integration in each chip duration, what judgement was received within current chip duration is divided into is 1 or 0, and string and conversion equipment are respectively got a chip transition by the RGB order and become serial signal.
Data Recapture Unit multiplies each other the serial signal that receives and each user's address code, then adjudicated by decision device, the sequence that obtains is carried out demodulation according to pre-specified modulation system, recover the information that the user sends, end message is transferred to network access equipment, and the realization terminal is connected with external network.
Owing in communication, being subject to the interference of noise, comprise that all visible lights except flashlight all can impact communication, the photoelectric detector of receiver also can generate heat in the process of carrying out opto-electronic conversion simultaneously, produces thermal noise, and these all can affect the performance of uplink communication.The length of user's quadrature address code, user's quantity, 1 number (weight) in the quadrature address code, the grade of decision device thresholding also can exert an influence to the communications reception effect.Wherein satisfy following relation between the length of orthogonal code, weight and the number of users:
, N is number of users, and L is orthogonal code length, and w is the orthogonal code weight.
Usually with the reception error rate 10 of receiver
-6As bottom line, the communication that is lower than this value is insecure.When orthogonal code length is 1024, weight is 5 o'clock, and number of users satisfies
The error rate in the situation is less than 10
-6, when orthogonal code length less than 1024 the time, the error rate is then greater than 10
-6When orthogonal code length is 1024, weight is 5, and when the decision threshold grade was 4 grades, number of users was less than 20 o'clock, and the error rate is lower than 10
-6, increase the number of users meeting so that the error rate rises, cause the communication quality variation; And when decision threshold was 5 grades, number of users was that 20 o'clock the error rate decreases when then being 4 grades than decision threshold, and communication quality makes moderate progress.By increasing the grade of decision threshold, increase the length of orthogonal code, limited subscriber quantity can play the effect that improves communication quality.
Claims (2)
1. the communication mode realized of system is two-way communication, and namely terminal can be passed through Network Capture information, also the information exchange of oneself can be crossed the base station and send on the network.
2. in the situation that satisfy the requirement of room lighting degree, at indoor realization downlink communication; Simultaneously take three-primary color LED as the basis, terminal can be modulated into digit pulse with in advance transmission information, send to the reception base station of ceiling by LED, each user with different quadrature address codes to show difference, after base station receiver receives light signal, light signal is demodulated to digital signal, identification is the information which user sends, and information is sent to external network, realize the uplink communication of terminal.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105871461A (en) * | 2016-05-17 | 2016-08-17 | 华南理工大学 | Multiple access method based on optical two-dimensional code and visible light communication system for implementing multiple access method |
| CN107147445A (en) * | 2017-05-10 | 2017-09-08 | 北京科技大学 | A kind of VISIBLE LIGHT SYSTEM multi-user communication method |
| CN111211835A (en) * | 2018-11-21 | 2020-05-29 | 绍兴钠钇光电有限公司 | Visible light communication method based on hidden channel |
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| US20070058987A1 (en) * | 2005-09-13 | 2007-03-15 | Kabushiki Kaisha Toshiba | Visible light communication system and method therefor |
| US20070294961A1 (en) * | 2006-06-23 | 2007-12-27 | Overhead Door Corporation | Calibration and setup unit for barrier operator control system |
| CN102324974A (en) * | 2011-07-08 | 2012-01-18 | 北京邮电大学 | A kind of visible light communication system and device thereof based on the OCDMA technology |
| CN102624451A (en) * | 2011-01-27 | 2012-08-01 | 郭丰亮 | Power line carrier-based LED visible light communication system |
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| US20030180056A1 (en) * | 2002-03-25 | 2003-09-25 | Alcatel | Optical receiver |
| US20070058987A1 (en) * | 2005-09-13 | 2007-03-15 | Kabushiki Kaisha Toshiba | Visible light communication system and method therefor |
| US20070294961A1 (en) * | 2006-06-23 | 2007-12-27 | Overhead Door Corporation | Calibration and setup unit for barrier operator control system |
| CN102624451A (en) * | 2011-01-27 | 2012-08-01 | 郭丰亮 | Power line carrier-based LED visible light communication system |
| CN102324974A (en) * | 2011-07-08 | 2012-01-18 | 北京邮电大学 | A kind of visible light communication system and device thereof based on the OCDMA technology |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105871461A (en) * | 2016-05-17 | 2016-08-17 | 华南理工大学 | Multiple access method based on optical two-dimensional code and visible light communication system for implementing multiple access method |
| CN105871461B (en) * | 2016-05-17 | 2018-06-22 | 华南理工大学 | A kind of multiple access method and its visible light communication system based on light Quick Response Code |
| CN107147445A (en) * | 2017-05-10 | 2017-09-08 | 北京科技大学 | A kind of VISIBLE LIGHT SYSTEM multi-user communication method |
| CN111211835A (en) * | 2018-11-21 | 2020-05-29 | 绍兴钠钇光电有限公司 | Visible light communication method based on hidden channel |
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