CN105471505A - Signal modulation method, signal modulation device, and visible light communication system - Google Patents
Signal modulation method, signal modulation device, and visible light communication system Download PDFInfo
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- CN105471505A CN105471505A CN201610049200.5A CN201610049200A CN105471505A CN 105471505 A CN105471505 A CN 105471505A CN 201610049200 A CN201610049200 A CN 201610049200A CN 105471505 A CN105471505 A CN 105471505A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
- H04B10/114—Indoor or close-range type systems
- H04B10/116—Visible light communication
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/501—Structural aspects
- H04B10/502—LED transmitters
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/516—Details of coding or modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/564—Power control
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Abstract
The invention discloses a signal modulation method. The signal modulation method is characterized in that original signals and a modulation order are acquired; constellation points can be determined according to the modulation order and a constellation construction rule, and the constellation construction rule can be acquired according to the Anscombe conversion principle, and i is the No.i constellation point; the emission power corresponding to the signal symbol of the original signal corresponding to each of the constellation points can be determined respectively; and the symbol of each of the original signals can be modulated to the optical signal according to the emission power. The constellation points can be determined according to the new constellation construction rule, and then the emission power corresponding to each of the symbols can be acquired. The constellation construction rule can be acquired according to the Anscombe conversion principle, and the noises of the poisson channel can be converted into the constant terms by the Anscombe conversion, and therefore the noises can be irrelevant to the signals, the influence of the noises on the signals can be reduced, the accuracy of the constellation points can be improved, and the performance of the system can be improved.
Description
Technical field
The application relates to technical field of visible light communication, particularly relates to a kind of signal modulating method, device and visible light communication system.
Background technology
The emerging mode of one as radio communication, visible light communication (VLC) develops rapidly because of the frequency spectrum resource of its green, controlled communication range, transmission speed etc. at a high speed.
Visible light communication system comprises optical signal launch part and light signal receiving unit, wherein, the signal of telecommunication carries out modulating rear carrier frequency to light-emitting diode (Light-EmittingDiode by optical signal launch part, LED) on light fixture, the visible ray sent by LED lamp carries out signal transmission, at signal receiving end, utilize photon detector that the light signal received is converted to the signal of telecommunication.In order to improve the sensitivity of photon detector, current employing single-photon avalanche diode (SinglePhotonAvalancheDiode, SPAD) as the means of reception, compared with the mode of the direct-detection light intensity adopted with general PD, SPAD is operated in the number of photons being arrived receiving terminal under Geiger mode angular position digitizer by avalanche effect record, is more finally converted into the signal of telecommunication.Because make use of the response mechanism of avalanche effect as light signal, possesses high sensitivity by this way.Again because object of observation changes into photon, so make the signal of telecommunication finally detected introduce the randomness of particle, transmission channel is made to change into Poisson channel.
But because Poisson channel is signal correction type channel, when transmit signal power is larger, channel quality is poorer, and systematic function is also affected.Therefore, a kind of signal modulating method that can adapt to Poisson channel is needed badly, with the problem of resolution system poor performance.
Summary of the invention
In view of this, this application provides a kind of signal modulating method, device and visible light communication system, to solve the problem of systematic function difference of the prior art.
For achieving the above object, the application provides following technical scheme:
A kind of signal modulating method, be applied to the reflector of visible light communication system, the receiver of described visible light communication system comprises: SPAD array, and the method comprises:
Obtain primary signal and order of modulation;
According to described order of modulation, and constellation builds criterion
determine each constellation point, it is obtain according to Anscombe shift theory that described constellation builds criterion, and i is i-th constellation point;
Determine the transmitting power that the signal code of the primary signal that each constellation point is corresponding is corresponding respectively;
According to described transmitting power, each symbol modulating described primary signal is light signal.
Preferably, described constellation structure criterion obtains according to following steps:
Determine the first signal z (k)=α x (k)+n (k) that receiver receives, wherein z (k) represents the kth symbol in the first signal, x (k) is for transmitting, and n (k) is poisson noise, and a is constant;
By described first signal according to formula
carry out Anscombe conversion, wherein, v represents the DC offset voltage being carried in described photon detector output, is constant, z'(k) represent and the result after Anscombe conversion is carried out to the symbol of the kth in the first signal;
Obtain the secondary signal obtained after described fortran, described secondary signal Gaussian distributed;
Each constellation point corresponding to described secondary signal is solved according to default constraints
described constraints is the minimum condition of the average light power of each constellation point.
Preferably, described constraints is:
Two different constellation point in constellation
minimum normalized cumulant between opening after radical sign is 1, namely
A kind of modulating apparatus, be applied to the reflector of visible light communication system, this device comprises:
Signal acquisition module, for obtaining primary signal and order of modulation;
Constellation point determination module, for according to described order of modulation, and constellation builds criterion
determine each constellation point;
Transmitting power determination module, for determining the transmitting power that the signal code of the primary signal that each constellation point is corresponding is corresponding respectively;
Modulation module, for according to described transmitting power, each symbol modulating described primary signal is light signal.
Preferably, also comprise: criterion determination module, comprising:
First signal determining unit, for determining the first signal z (k)=α x (k)+n (k) that receiver receives, wherein z (k) represents the kth symbol in the first signal, x (k) is for transmitting, n (k) is poisson noise, and a is constant;
Converter unit, for by described first signal according to formula
carry out Anscombe conversion, wherein, v represents the DC offset voltage being carried in described photon detector output, is constant, z'(k) represent and the result after Anscombe conversion is carried out to the symbol of the kth in the first signal;
Secondary signal obtains unit, for obtaining the secondary signal obtained after described fortran, and described secondary signal Gaussian distributed;
Constellation point solves unit, for solving each constellation point corresponding to described secondary signal according to default constraints
described constraints is the minimum condition of the average light power of each constellation point, and i is i-th constellation point.
Preferably, comprising: reflector, LED luminescence chip and receiver, wherein, described receiver comprises: SPAD array;
Described reflector is used for: obtain primary signal and order of modulation, and according to described order of modulation, and constellation builds criterion
determine each constellation point, determine the transmitting power that the signal code of the primary signal that each constellation point is corresponding is corresponding respectively, according to described transmitting power, each symbol modulating described primary signal is light signal;
Described LED luminescence chip is used for described optical signal transmission to described receiver;
Described receiver is used for, and receives described light signal, and carries out demodulation, obtains described primary signal.
Preferably, described reflector comprises: FPGA.
Known via above-mentioned technical scheme, in signal modulating method disclosed in the embodiment of the present application, build criterion according to new constellation and determine each constellation point, and then obtain transmitting power corresponding to each symbol.Constellation builds criterion and obtains according to Anscombe shift theory, because the noise in Poisson channel can be converted to constant term by Anscombe conversion, thus make it possible to noise and signal and have nothing to do, reduce the impact of noise on signal, thus improve the accuracy of constellation point, and then improve the performance of system.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present application or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only the embodiment of the application, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to the accompanying drawing provided.
The flow chart of Fig. 1 a kind of signal modulating method disclosed in the embodiment of the present application;
The flow chart of Fig. 2 another signal modulating method disclosed in the embodiment of the present application;
The structural representation of Fig. 3 a kind of modulating apparatus disclosed in the embodiment of the present application;
The structural representation of Fig. 4 another modulating apparatus disclosed in the embodiment of the present application;
Fig. 5 structural representation that a kind of visible light communication is pained disclosed in the embodiment of the present application.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present application, be clearly and completely described the technical scheme in the embodiment of the present application, obviously, described embodiment is only some embodiments of the present application, instead of whole embodiments.Based on the embodiment in the application, those of ordinary skill in the art are not making the every other embodiment obtained under creative work prerequisite, all belong to the scope of the application's protection.
A kind of flow process of signal modulating method disclosed in the embodiment of the present application as shown in Figure 1, is applied to the reflector of visible light communication system, and the receiver of described visible light communication system comprises: SPAD array.SPAD adopts the means detecting photon number, carries out signals collecting, in view of single SPAD once can only capture a photon, therefore adopts SPAD array as receiver to improve detectability.The method comprises:
Step S101: obtain primary signal and order of modulation;
Order of modulation is K.When order of modulation is 2, the two states that flickers of LED can be utilized to represent 0,1 two signals.And when order of modulation is the integer being greater than 2, then needing to utilize different bright intensity, that is, power level represents different symbols.
Step S102: according to described order of modulation, and constellation builds criterion
determine each constellation point, it is obtain according to Anscombe shift theory that described constellation builds criterion;
Disclosed in the embodiment of the present application, constellation building process as shown in Figure 2, comprising:
Step S201: determine the first signal z (k)=α x (k)+n (k) that receiver receives, wherein z (k) represents the kth symbol in the first signal, x (k) is for transmitting, and n (k) is poisson noise, and a is constant;
Step S202: by described first signal according to formula
carry out Anscombe conversion, wherein, v represents the DC offset voltage being carried in described photon detector output, is constant, z'(k) represent and the result after Anscombe conversion is carried out to the symbol of the kth in the first signal;
Now the structure of z ' (k) becomes the form that signal adds white Gaussian noise.So can gaussian signal process be regarded at transform-domain signals.
Step S203: obtain the secondary signal obtained after described fortran, described secondary signal Gaussian distributed;
Step S204: solve each constellation point corresponding to described secondary signal according to default constraints
described constraints is the minimum condition of the average light power of each constellation point, and i is i constellation point.
Signal after conversion is still processed according to gaussian signal.
Described constraints is:
Two different constellation point in constellation
minimum normalized cumulant between opening after radical sign is 1, namely
In the process building constellation, after the Received signal strength of obeying Poisson distribution is carried out Anscombe conversion by the embodiment of the present application, Anscombe conversion is only effective for Poisson distribution, and form is
contain the signal of poisson noise through this conversion, the form that signal adds Gaussian noise can be become, by this conversion, the original poisson noise relevant with signal is converted into the Gaussian noise irrelevant with signal.
The distribution of the known z ' of mathematic(al) law is had to have stable variance after conversion.Original constellation building process is, known signal z and solve signal constellation point, the expectation of this constellation point i.e. z.And after the conversion, just become the constellation point solving z '.
Before this constellation building process occurs in signal madulation.
Step S103: determine the transmitting power that the signal code of the primary signal that each constellation point is corresponding is corresponding respectively;
Step S104: according to described transmitting power, each symbol modulating described primary signal is light signal.
In signal modulating method disclosed in the embodiment of the present application, build criterion according to new constellation and determine each constellation point, and then obtain transmitting power corresponding to each symbol, and then signal is modulated, ensure that the signal after modulation can better transmit in the channel, the performance of elevator system.Constellation builds criterion and obtains according to Anscombe shift theory, because the noise in Poisson channel can be converted to constant term by Anscombe conversion, thus make it possible to noise and signal and have nothing to do, reduce the impact of noise on signal, thus improve the accuracy of constellation point, and then improve the performance of system.
The application also discloses a kind of modulating apparatus, and it is applied to the reflector of visible light communication system, and the structure of this device as shown in Figure 3, comprising:
Signal acquisition module 301, for obtaining primary signal and order of modulation;
Constellation point determination module 302, for according to described order of modulation, and constellation builds criterion
determine each constellation point;
Transmitting power determination module 303, for determining the transmitting power that the signal code of the primary signal that each constellation point is corresponding is corresponding respectively;
Modulation module 304, for according to described transmitting power, each symbol modulating described primary signal is light signal.
Further, it also comprises:
Criterion determination module 305, its structure as shown in Figure 4, comprising:
First signal determining unit 3051, for determining the first signal z (k)=α x (k)+n (k) that receiver receives, wherein z (k) represents the kth symbol in the first signal, x (k) is for transmitting, n (k) is poisson noise, and a is constant;
Converter unit 3052, for by described first signal according to formula
carry out Anscombe conversion, wherein, v represents the DC offset voltage being carried in described photon detector output, is constant, z'(k) represent and the result after Anscombe conversion is carried out to the symbol of the kth in the first signal;
Secondary signal obtains unit 3053, for obtaining the secondary signal obtained after described fortran, and described secondary signal Gaussian distributed;
Constellation point solves unit 3054, for solving each constellation point corresponding to described secondary signal according to default constraints
described constraints is the minimum condition of the average light power of each constellation point, and i is i-th constellation point.
Modulating apparatus disclosed in the embodiment of the present application, builds criterion according to new constellation and determines each constellation point, and then obtain transmitting power corresponding to each symbol, then modulate signal.Constellation builds criterion and obtains according to Anscombe shift theory, because the noise in Poisson channel can be converted to constant term by Anscombe conversion, thus make it possible to noise and signal and have nothing to do, reduce the impact of noise on signal, thus improve the accuracy of constellation point, and then improve the performance of system.
The application also discloses a kind of VISIBLE LIGHT SYSTEM, and its structure as shown in Figure 5, comprising: reflector 501, LED luminescence chip 502 and receiver 503, and wherein, described receiver comprises: SPAD array 5031.
Described reflector 501 for: obtain primary signal and order of modulation, according to described order of modulation, and constellation builds criterion
determine each constellation point, determine the transmitting power that the signal code of the primary signal that each constellation point is corresponding is corresponding respectively, according to described transmitting power, each symbol modulating described primary signal is light signal;
Described LED luminescence chip 502 is for giving described receiver by described optical signal transmission;
Described receiver 503 for, receive described light signal, and carry out demodulation, obtain described primary signal.
Constellation builds criterion
deterministic process be: determine the first signal z (k)=α x (k)+n (k) that receiver receives, wherein z (k) represents the kth symbol in the first signal, x (k) is for transmitting, n (k) is poisson noise, and a is constant; By described first signal according to formula
carry out Anscombe conversion, wherein, v represents the DC offset voltage being carried in described photon detector output, is constant, z'(k) represent and the result after Anscombe conversion is carried out to the symbol of the kth in the first signal; Obtain the secondary signal obtained after described fortran, described secondary signal Gaussian distributed; Each constellation point corresponding to described secondary signal is solved according to default constraints
described constraints is the minimum condition of the average light power of each constellation point.
Receiver is when carrying out signal receiving, and the constellation point that reflector also will be utilized to use when sending signal carries out demodulation to signal.
In the present embodiment, as shown in FIG., receiver carries out the reception of signal except comprising SPAD array, also comprise FPGA5032, carries out solution reconciliation process to signal, and in like manner, reflector also can be realized the modulation of signal and the process of signal transacting by FPGA.
In visible light communication system disclosed in the embodiment of the present application, reflector utilizes new constellation structure criterion to determine each constellation point, and then obtains transmitting power corresponding to each symbol.Constellation builds criterion and obtains according to Anscombe shift theory, because the noise in Poisson channel can be converted to constant term by Anscombe conversion, thus make it possible to noise and signal and have nothing to do, reduce the impact of noise on signal, thus improve the accuracy of constellation point, and then improve the performance of system.
It should be noted that, each embodiment in this specification all adopts the mode of going forward one by one to describe, and what each embodiment stressed is the difference with other embodiments, between each embodiment identical similar part mutually see.For device class embodiment, due to itself and embodiment of the method basic simlarity, so description is fairly simple, relevant part illustrates see the part of embodiment of the method.
Finally, also it should be noted that, in this article, the such as relational terms of first and second grades and so on is only used for an entity or operation to separate with another entity or operating space, and not necessarily requires or imply the relation that there is any this reality between these entities or operation or sequentially.And, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thus make to comprise the process of a series of key element, method, article or equipment and not only comprise those key elements, but also comprise other key elements clearly do not listed, or also comprise by the intrinsic key element of this process, method, article or equipment.When not more restrictions, the key element limited by statement " comprising ... ", and be not precluded within process, method, article or the equipment comprising described key element and also there is other identical element.
To the above-mentioned explanation of the disclosed embodiments, those skilled in the art are realized or uses the present invention.To be apparent for a person skilled in the art to the multiple amendment of these embodiments, General Principle as defined herein can without departing from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention can not be restricted to these embodiments shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.
The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (7)
1. a signal modulating method, is characterized in that, is applied to the reflector of visible light communication system, and the receiver of described visible light communication system comprises: SPAD array, and the method comprises:
Obtain primary signal and order of modulation;
According to described order of modulation, and constellation builds criterion
determine each constellation point, it is obtain according to Anscombe shift theory that described constellation builds criterion, and i is i-th constellation point;
Determine the transmitting power that the signal code of the primary signal that each constellation point is corresponding is corresponding respectively;
According to described transmitting power, each symbol modulating described primary signal is light signal.
2. method according to claim 1, is characterized in that, described constellation builds criterion and obtains according to following steps:
Determine the first signal z (k)=α x (k)+n (k) that receiver receives, wherein z (k) represents the kth symbol in the first signal, x (k) is for transmitting, and n (k) is poisson noise, and a is constant;
By described first signal according to formula
carry out Anscombe conversion, wherein, v represents the DC offset voltage being carried in described photon detector output, is constant, z'(k) represent and the result after Anscombe conversion is carried out to the symbol of the kth in the first signal;
Obtain the secondary signal obtained after described fortran, described secondary signal Gaussian distributed;
Each constellation point corresponding to described secondary signal is solved according to default constraints
described constraints is the minimum condition of the average light power of each constellation point.
3. method according to claim 2, is characterized in that, described constraints is:
Two different constellation point s in constellation,
minimum normalized cumulant between opening after radical sign is 1, namely
4. a modulating apparatus, is characterized in that, is applied to the reflector of visible light communication system, and this device comprises:
Signal acquisition module, for obtaining primary signal and order of modulation;
Constellation point determination module, for according to described order of modulation, and constellation builds criterion
determine each constellation point;
Transmitting power determination module, for determining the transmitting power that the signal code of the primary signal that each constellation point is corresponding is corresponding respectively;
Modulation module, for according to described transmitting power, each symbol modulating described primary signal is light signal.
5. device according to claim 4, is characterized in that, also comprises: criterion determination module, comprising:
First signal determining unit, for determining the first signal z (k)=α x (k)+n (k) that receiver receives, wherein z (k) represents the kth symbol in the first signal, x (k) is for transmitting, n (k) is poisson noise, and a is constant;
Converter unit, for by described first signal according to formula
carry out Anscombe conversion, wherein, v represents the DC offset voltage being carried in described photon detector output, is constant, z'(k) represent and the result after Anscombe conversion is carried out to the symbol of the kth in the first signal;
Secondary signal obtains unit, for obtaining the secondary signal obtained after described fortran, and described secondary signal Gaussian distributed;
Constellation point solves unit, for solving each constellation point corresponding to described secondary signal according to default constraints
described constraints is the minimum condition of the average light power of each constellation point, and i is i-th constellation point.
6. a visible light communication system, is characterized in that, comprising: reflector, LED luminescence chip and receiver, and wherein, described receiver comprises: SPAD array;
Described reflector is used for: obtain primary signal and order of modulation, and according to described order of modulation, and constellation builds criterion
determine each constellation point, determine the transmitting power that the signal code of the primary signal that each constellation point is corresponding is corresponding respectively, according to described transmitting power, each symbol modulating described primary signal is light signal;
Described LED luminescence chip is used for described optical signal transmission to described receiver;
Described receiver is used for, and receives described light signal, and carries out demodulation, obtains described primary signal.
7. system according to claim 6, is characterized in that, described reflector comprises: FPGA.
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