CN105721056A - Method and system for reducing light source LED nonlinearity in visible light communication system - Google Patents
Method and system for reducing light source LED nonlinearity in visible light communication system Download PDFInfo
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- 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
Abstract
The invention provides a method and system for reducing light source LED nonlinearity in a visible light communication system. According to the method and the system, signal distortion resulting from the nonlinearity characteristic of the LEDs can be eliminated from the sent signals themselves. The method comprises following steps of obtaining to-be-sent signal sequences; processing the signal sequences based on a selective mapping algorithm, thus obtaining a set of multi-carrier signal sequence with the minimum peak-to-average power ratio; converting the multi-carrier signal sequence into serial signals; generating a set of marking sequence with same length to the serial signals; if the amplitude value of the serial signals is more than an LED saturation threshold value, multiplying a pre-distortion compression coefficient by the multi-carrier signals of which amplitude value is more than the LED saturation threshold value; and assigning 1 at corresponding position in the marking sequence. The method and the system are applicable to the technical field of visible light wireless communication.
Description
Technical field
The present invention relates to visible ray wireless communication technology field, particularly relate to a kind of reduction visible light communication system light source led non-linear method and system.
Background technology
Development along with wireless communication technology and lighting industry, visible light emitting diode (LED) radio communication as a kind of new technique utilizing white light LEDs to communicate, there is visible ray aboundresources, energy-saving safe, message capacity is big, tranmitting frequency is high, transfer rate is fast, without electromagnetic interference, need not the advantage such as radio frequency card.Visible LED radio communication has good application prospect, future communications field occupies an important position and is worth, with LED for indoor visible light communication signal optical source, it has energy-saving, intellectuality, informationization, safe, the advantages such as electromagnetic-radiation-free, it is seen that optic communication research is chosen as one of the whole world 50 big scientific and technological inventions in 2011 by Time.
Visible light communication system has many advantages making up Radio-Frequency Wireless Communication system defect, but because signal optical source LED unintentional nonlinearity transmission characteristic makes signal optical source LED become one of maximum nonlinear device in system.Owing to the modulation bandwidth of visible ray wireless communication system is affected by the nonlinear characteristic of LED, and the linear transfer of light source led is limited in scope, therefore in the transmitting procedure of LED component, when signal amplitude is higher than the saturation threshold value of LED linear scope, the amplitude of signal will be unable to normal output, and such amplitude signal just distortion is amplitude is the distorted signal of LED saturation threshold value.The amplitude multi-carrier signal distorted enters visible light communication channel, receiving end cannot recover primary signal after receiving, this is not only reduced the reliability of visible ray wireless communication system by the non-linear impact caused of LED, also can reduce light source led working life because a large amount of signals arrive LED saturation threshold value.
In prior art, change LED bias current and can alleviate the method for the non-linear effects of light source led in visible ray radio communication as a kind of, concrete, the central value of detection LED linear transmission range, analyze and calculate the average current value sending signal, LED bias current is set to the central value of LED linear transmission range so that send the average current value of signal close to bias current value.The method is to be configured according to device itself, simple to operate, but, do not do non-linear reduction from the signal itself sent and process, and the method is suitable only for the system of lower complexity.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of reduction visible light communication system light source led non-linear method and system, non-linear reduction process and the problem being only applicable to the system of lower complexity is done with the signal itself from transmission that do not have solved existing for prior art.
For solving above-mentioned technical problem, the embodiment of the present invention provides one to reduce visible light communication system light source led non-linear method, including:
Obtain signal sequence to be sent；
Based on selected mapping method algorithm, described signal sequence is processed, obtain one group of multi-carrier signal sequence that peak-to-average power ratio is minimum；
Described multi-carrier signal sequence is converted to serial signal, and generates labelled sequence one group identical with described serial signal length；
If the amplitude of described serial signal is more than LED saturation threshold value, then amplitude is multiplied by predistortion coefficient of compressibility more than the multi-carrier signal of LED saturation threshold value, and in labelled sequence correspondence position assignment 1.
Further, described based on selected mapping method algorithm, described signal sequence being processed, the one group of multi-carrier signal sequence obtaining peak-to-average power ratio minimum includes:
The a group phase rotation coefficient sequence generated based on selected mapping method algorithm is multiplied with described signal sequence respectively, obtains a group selection mapping signal sequence；
Described a group selection mapping signal sequence is carried out inverse fast fourier transform respectively, obtains a group multi-carrier signal sequence；
From described a group multi-carrier signal sequence, obtain one group of multi-carrier signal sequence that peak-to-average power ratio is minimum.
Further, described method also includes:
If the amplitude of described serial signal is less than LED saturation threshold value, then correspondence position assignment 0 in labelled sequence.
Further, described method also includes:
The signal that receiving terminal is received carries out amplitude limit recovery；
The described signal that receiving terminal is received carries out amplitude limit and recovers to include:
Detect to the received signal at receiving terminal；
If the mark value detected in labelled sequence is 1, then the reception signal of correspondence position and predistortion coefficient of compressibility is divided by and carries out amplitude limit recovery；
If the mark value detected in labelled sequence is 0, then the reception signal of correspondence position remains unchanged.
Further, the described signal that receiving terminal is received includes after carrying out amplitude limit recovery:
Obtain one group of phase rotation coefficient sequence minimum in a group phase rotation coefficient sequence that selected mapping method algorithm generates；
By amplitude limit recover after signal after fast Fourier transform divided by described minimum phase rotation coefficient sequence.
The embodiment of the present invention also provides for a kind of reduction nonlinear system of visible light communication system light source led, and at transmitting terminal, described system includes:
Signal sequence acquiring unit: for obtaining signal sequence to be sent；
Selected mapping method unit: for described signal sequence being processed based on selected mapping method algorithm, obtain one group of multi-carrier signal sequence that peak-to-average power ratio is minimum；
Labelled sequence generates unit: for described multi-carrier signal sequence is converted to serial signal, and generate labelled sequence one group identical with described serial signal length；
First can recover clipping unit: if for the amplitude of described serial signal more than LED saturation threshold value, then more than the multi-carrier signal of LED saturation threshold value amplitude is multiplied by predistortion coefficient of compressibility, and in labelled sequence correspondence position assignment 1.
Further, described selected mapping method unit includes:
Multiplier module, for a group phase rotation coefficient sequence generated based on selected mapping method algorithm being multiplied with described signal sequence respectively, obtains a group selection mapping signal sequence；
Inverse transform module, for described a group selection mapping signal sequence is carried out inverse fast fourier transform respectively, obtains a group multi-carrier signal sequence；
Acquisition module, for, from described a group multi-carrier signal sequence, obtaining one group of multi-carrier signal sequence that peak-to-average power ratio is minimum.
Further, at transmitting terminal, described system also includes:
Second can recover clipping unit: if for the amplitude of described serial signal less than LED saturation threshold value, then correspondence position assignment 0 in labelled sequence.
Further, at receiving terminal, described system includes:
Recovery unit: the signal for receiving terminal is received carries out amplitude limit recovery；
Described recovery unit includes:
Detection module, for detecting to the received signal at receiving terminal；
Amplitude limit recovers module, if the mark value for detecting in labelled sequence is 1, then the reception signal of correspondence position and predistortion coefficient of compressibility is divided by and carries out amplitude limit recovery；
Described amplitude limit recovers module, if the mark value being additionally operable to detect in labelled sequence is 0, then the reception signal of correspondence position remains unchanged.
Further, at receiving terminal, described system also includes:
Phase rotation coefficient acquiring unit: for obtaining one group of phase rotation coefficient sequence minimum in a group phase rotation coefficient sequence that selected mapping method algorithm generates；
Converter unit, is used for the signal after being recovered by amplitude limit after fast Fourier transform divided by described minimum phase rotation coefficient sequence.
Having the beneficial effect that of the technique scheme of the present invention:
In such scheme, utilize selected mapping method algorithm that the signal sequence to be sent got is processed, obtain one group of multi-carrier signal sequence that peak-to-average power ratio is minimum；Described multi-carrier signal sequence is converted to serial signal, and generates labelled sequence one group identical with described serial signal length；If the amplitude of described serial signal is more than LED saturation threshold value, then amplitude is multiplied by predistortion coefficient of compressibility more than the multi-carrier signal of LED saturation threshold value, and in labelled sequence correspondence position assignment 1 (margining amplitude technique can be recovered), ensure that described serial signal normally exports within the scope of LED linear, so, utilize selected mapping method algorithm and margining amplitude technique can be recovered in phase and amplitude two, multi-carrier signal amplitude range be controlled, it is made to transmit within the scope of LED linear, amplitude multi-carrier signal is overcome to transmit the non-linear effects suffered in light source led, thus eliminating the signal distortion that LED nonlinear characteristic causes, the communication system possessing light source led is made to obtain higher reliability, ensure the transmission quality of communication system.
Accompanying drawing explanation
The flow chart one reducing visible light communication system light source led non-linear method that Fig. 1 provides for the embodiment of the present invention；
The principle schematic of the transmitting terminal that Fig. 2 provides for the embodiment of the present invention；
The flowchart 2 reducing visible light communication system light source led non-linear method that Fig. 3 provides for the embodiment of the present invention；
The DCO-OFDM signal CCDF/PAPR simulation curve that Fig. 4 provides for the embodiment of the present invention；
The DCO-OFDM signal waveform comparison diagram inputing to LED and LED output that Fig. 5 provides for the embodiment of the present invention；
The visible light communication DCO-OFDM error rate of system simulation curve based on algorithms of different that Fig. 6 provides for the embodiment of the present invention；
The structural representation reducing the nonlinear system of visible light communication system light source led that Fig. 7 provides for the embodiment of the present invention.
Detailed description of the invention
For making the technical problem to be solved in the present invention, technical scheme and advantage clearly, it is described in detail below in conjunction with the accompanying drawings and the specific embodiments.
The present invention is directed to the existing signal not having from transmission itself and do non-linear reduction process and the problem being only applicable to the system of lower complexity, it is provided that a kind of reduction visible light communication system light source led non-linear method and system.
Embodiment one
Shown in Fig. 1, the reduction visible light communication system light source led non-linear method that the embodiment of the present invention provides, including:
S1: obtain signal sequence to be sent；
S2: based on selected mapping method algorithm (SelectiveMapping, SLM), described signal sequence is processed, obtains one group of multi-carrier signal sequence that peak-to-average power ratio (PeaktoAveragePowerRatio, PAPR) is minimum；
S3: described multi-carrier signal sequence is converted to serial signal, and generates labelled sequence one group identical with described serial signal length；
S4: if the amplitude of described serial signal is more than LED saturation threshold value, then be multiplied by predistortion coefficient of compressibility by amplitude more than the multi-carrier signal of LED saturation threshold value, and in labelled sequence correspondence position assignment 1.
Reduction visible light communication system light source led non-linear method described in the embodiment of the present invention, utilizes selected mapping method algorithm that the signal sequence to be sent got is processed, and obtains one group of multi-carrier signal sequence that peak-to-average power ratio is minimum；Described multi-carrier signal sequence is converted to serial signal, and generates labelled sequence one group identical with described serial signal length；If the amplitude of described serial signal is more than LED saturation threshold value, then amplitude is multiplied by predistortion coefficient of compressibility more than the multi-carrier signal of LED saturation threshold value, and in labelled sequence correspondence position assignment 1 (margining amplitude technique can be recovered), ensure that described serial signal normally exports within the scope of LED linear, so, utilize selected mapping method algorithm and margining amplitude technique can be recovered in phase and amplitude two, multi-carrier signal amplitude range be controlled, it is made to transmit within the scope of LED linear, amplitude multi-carrier signal is overcome to transmit the non-linear effects suffered in light source led, thus eliminating the signal distortion that LED nonlinear characteristic causes, the communication system possessing light source led is made to obtain higher reliability, ensure the transmission quality of communication system.
In the embodiment of the present invention, the selected mapping method algorithm adopted, belong to the method reducing multi-carrier signal peak equal power ratio, the peak value of signal can be reduced from the angle of signal phase, and do not introduce signal distortion, adopt simultaneously and can recover margining amplitude technique (RestorableClipping, RC), in conjunction with predistortion theory, further signal amplitude is compressed from the angle of signal amplitude, the serious signal distortion that LED non-linear effects brings can be avoided when transmitting terminal transmits, thus ensureing can recover, at receiving terminal, the primary signal that transmitting terminal sends exactly, it is finally reached the purpose promoting systematic function, concrete, generate labelled sequence record amplitude still higher than the signal location of LED saturation threshold value, and carry out recovering compression to this position signalling, make the linear transfer scope that signal amplitude scope meets LED, thus reducing visible light communication system LED non-linear effects, wherein, predistortion coefficient of compressibility is less than 1, so, not only avoid a large amount of distortions of signal, increase again the reliability of communication system.
In the embodiment of the present invention, margining amplitude technique maybe can be recovered compared to being used alone selected mapping method algorithm, associating pre-distortion technology in conjunction with two kinds of methods can reduce system complexity, signal is carried out selectivity and can recover amplitude limit, namely when signal amplitude is higher than LED linear scope, signal is carried out clipping operation, and design a labelled sequence record and carry out the signal location of clipping operation, so that the limitation signal of this position is recovered by receiving terminal, if signal amplitude is within LED linear scope, then do not do any pre-distortion.
Shown in Fig. 2, before utilizing selected mapping method algorithm that described signal sequence is processed, also include step:
1) baseband modulation, carries out baseband modulation at transmitting terminal to the primary signal (such as, binary bit sequence) of input, obtains the band passband signals of serial；Namely the primary signal inputted carries out M-ary Quadrature Amplitude modulation (MultipleQuadratureAmplitudeModulation, MQAM) constellation mapping, obtains the MQAM signal of serial；
2) serioparallel exchange (SerialtoParallel, S/P), the MQAM signal of the serial obtained is carried out serial to parallel conversion so that it is be transformed to the signal sequence of N (N is IFFT point number) road parallel transmission, for example, it is possible to be expressed as: signal sequence X.
In the detailed description of the invention of aforementioned reduction visible light communication system light source led non-linear method, further, described based on selected mapping method algorithm, described signal sequence being processed, the one group of multi-carrier signal sequence obtaining peak-to-average power ratio minimum includes:
The a group phase rotation coefficient sequence generated based on selected mapping method algorithm is multiplied with described signal sequence respectively, obtains a group selection mapping signal sequence；
Described a group selection mapping signal sequence is carried out inverse fast fourier transform (InverseFastFourierTransform, IFFT) respectively, obtains a group multi-carrier signal sequence；
From described a group multi-carrier signal sequence, obtain one group of multi-carrier signal sequence that peak-to-average power ratio is minimum.
In the embodiment of the present invention, selected mapping method algorithm is utilized to generate a group phase rotation coefficient sequence, and a group phase rotation coefficient sequence is multiplied with described signal sequence X respectively, obtain the SLM signal sequence that a group is different, thus changing the phasing matrix of signal sequence X, to avoid the high peak valve signal caused because of same phase in communications system transmission, thus reducing the peak-to-average power ratio of multi-carrier signal, reaching the first step in visible ray radio communication and reducing the purpose of signal amplitude.
In the embodiment of the present invention, described a group selection mapping signal sequence is carried out inverse fast fourier transform (multi-carrier modulation) respectively, obtain a group multi-carrier signal sequence, by selected mapping method signal sequence is carried out multi-carrier modulation, system transfer rate can be improved, it is ensured that signal orthogonalization and without intersymbol interference.Further, also determining the peak-to-average power ratio of a group multi-carrier signal sequence respectively, from the peak-to-average power ratio of a group multi-carrier signal sequence determined, the one group of multi-carrier signal sequence obtaining peak-to-average power ratio minimum carries out follow-up transmission.
In the embodiment of the present invention, the multi-carrier signal sequence with minimum peak-to-average power ratio got is carried out parallel serial conversion so that it is be transformed to the signal of 1 tunnel serial transmission.
In the embodiment of the present invention, detect the peak value of described serial signal, and be simultaneously generated labelled sequence one group identical with this serial signal length, if the amplitude of described serial signal is less than LED saturation threshold value, then without any operatively normal transmission, and correspondence position in labelled sequence can be composed 0 value；
If the amplitude of described serial signal is more than the signal of LED saturation threshold value, then amplitude is multiplied by predistortion coefficient of compressibility more than the multi-carrier signal of LED saturation threshold value, carries out predistortion and can recover amplitude limit, and in labelled sequence correspondence position assignment 1.
The embodiment of the present invention, can recover margining amplitude technique is a kind of follow-on limiting technology, combines predistortion theory and amplitude signal is carried out predistortion amplitude limiting processing, be further ensured that signal transmits in the led and will not suffer the nonlinear impact of LED.
In the embodiment of the present invention, it is possible to use emitter/signal optical source LED by selected mapping method algorithm with can recover the signal that margining amplitude technique processed and send, at receiving terminal, first, will carry out amplitude limit recovery to the received signal；Concrete, detect to the received signal at receiving terminal；If the mark value detected in labelled sequence is 1, then the reception signal of correspondence position and predistortion coefficient of compressibility is divided by and carries out amplitude limit recovery；If the mark value detected in labelled sequence is 0, then the reception signal of correspondence position remains unchanged；Then, one group of phase rotation coefficient sequence minimum in a group phase rotation coefficient sequence that selected mapping method algorithm generates is obtained；The signal obtained divided by described minimum phase rotation coefficient sequence, and is carried out solving after baseband modulation and exports final signal after fast Fourier transform by the signal after being recovered by amplitude limit.
In conjunction with specific example, it is seen that light wireless communication system is for DCO-OFDM system, shown in Fig. 3, the reduction visible light communication system light source led non-linear method described in the embodiment of the present invention is further described in detail:
First, at transmitting terminal, the primary signal of input is carried out baseband modulation and serioparallel exchange, the primary signal of serial is transformed to the data of N (N is DCO-OFDM system subcarrier number) road parallel transmission.Before IFFT converts, selected mapping method algorithm is utilized to generate the phase rotation coefficient sequence that a group is differentAnd after described a group phase rotation coefficient sequence being multiplied respectively, carry out the IFFT conversion of N point with parallel data, it is achieved the multi-carrier modulation to input signal.Selecting one group of DCO-OFDM signal with minimum peak-to-average power ratio after IFFT conversion, now the DCO-OFDM time-domain sampling signal before adding DC-offset operation is represented by:
Afterwards, then carrying out recovering clipping operation to this group DCO-OFDM signal, preset a threshold value A, this threshold value should be equal to LED saturation threshold value, is simultaneously generated the labelled sequence C that one group of length is Nk=[C0,C1,…,Ck,…,CN-1].Input signal is carried out peakvalue's checking, and amplitude can glitch-free be transmitted less than the signal of threshold value, simultaneously by corresponding CkIt is labeled as 0；Amplitude is then multiplied with predistortion coefficient of compressibility m (m is less than 1) more than the signal of threshold value, simultaneously by corresponding CkBeing labeled as 1, signal and labelled sequence after amplitude limit can be expressed as:
So, reduce the peak value of signal from the angle of phase place first with selected mapping method algorithm, then, utilization can recover clipping operation and reduce further the amplitude range of signal from the angle of amplitude, although slightly reducing the performance number of signal, but the suppression of LED non-linear effects is served great effect, it is to avoid the irrecoverable signal distortion that causes because LED is non-linear so that signal before LED input and LED export after all keep identical waveform.
Signal optical source LED sends through selected mapping method algorithm and can recover after the DCO-OFDM signal that margining amplitude technique processed visible ray radio communication channel in inlet chamber, and the signal that photodetector receives is expressed as yk=[y0,y1,…,yk,…,yN-1], now again through the labelled sequence received to receiving sequences ykRecover.If detecting, mark value is 0, then the reception signal of correspondence position remains unchanged；If detecting, mark value is 1, then the reception signal of correspondence position and predistortion coefficient of compressibility m are divided by, and signal after being restored also is expressed as:
Signal after recovery is divided by minimum phase rotation coefficient after FFT, and the signal obtained exports final signal after carrying out solution baseband modulation.
Finally, the embodiment of the present invention is verified by the emulation platform building a visible light communication DCO-OFDM system, the simulation parameter that the present invention uses is: DCO-OFDM sub-carrier number is 256, the DCO-OFDM symbol numbers of input is 10000, adopt 16QAM modulation system, threshold value A=600mA, predistortion compression ratio m=0.7.
Fig. 4 is the DCO-OFDM signal CCDF/PAPR simulation curve adopting pre-distortion technology, and emulation is directed to the multicarrier DCO-OFDM signal of visible light communication system, wherein sub-carrier number N=256, have employed 16QAM modulation.Fig. 4 is respectively compared single passage selected mapping method module and single passage can recover clipping module and the signal peak-to-average power power ratio combining pre-distortion technology that the present invention proposes.In Fig. 4, abscissa represents the threshold value of PAPR, and unit is dB, and vertical coordinate represents that input signal PAPR exceedes the probability of a certain threshold value, i.e. complementary cumulative distribution function (CCDF).With reference to Fig. 4 it can be seen that the associating pre-distortion technology that the present invention proposes can significantly reduce the PAPR of DCO-OFDM system.
Fig. 5 is the DCO-OFDM signal waveform comparison diagram inputing to LED and LED output shown in the embodiment of the present invention, it is respectively compared several algorithm eradicating efficacy to LED non-linear effects, primary signal, selected mapping method signal and can recover limitation signal and all suffered the nonlinear impact of LED, be equivalent to experienced by expendable amplitude limit.And the signal that have employed the associating pre-distortion technology that the present invention proposes does not suffer the nonlinear impact of LED, before and after LED output, do not change the features such as signal waveform amplitude, say, that complete after signal experience predistortion transmit out within the scope of LED linear.
Fig. 6 is the visible light communication DCO-OFDM error rate of system simulation curve in the embodiment of the present invention based on algorithms of different, and in Fig. 6, abscissa represents that signal to noise ratio, vertical coordinate represent the signal error rate under different signal to noise ratio.As shown in Figure 6, utilize the bit error rate performance combining pre-distortion technology elimination LED non-linear effects that the embodiment of the present invention provides more much lower than the original DCO-OFDM without any elimination LED Nonlinear Processing, it is that bit error rate during 16dB is only 0.0001 in signal to noise ratio, improves nearly 4dB compared to the signal of primary signal and single utilization selected mapping method algorithm.
To sum up, the embodiment of the present invention combines the high reliability of selected mapping method algorithm and can recover the predistortion effect of margining amplitude technique, will not cause transmitting terminal signal distortion, and accurately recover the function of compressed signal according to receiving terminal labelled sequence.Through experimental verification, with compared with the original scheme of predistortion operation, this programme restrained effectively the signal distortion impact that in visible light communication system, LED nonlinear characteristic is brought, and significantly reduces the bit error rate of visible light communication multicarrier system, thus Integral lifting system performance.
Embodiment two
The present invention also provides for a kind of detailed description of the invention reducing the nonlinear system of visible light communication system light source led, owing to the reduction nonlinear system of visible light communication system light source led provided by the invention is corresponding with the detailed description of the invention of aforementioned reduction visible light communication system light source led non-linear method, this reduction nonlinear system of visible light communication system light source led can realize the purpose of the present invention by the process step in execution said method detailed description of the invention, therefore the explanation in above-mentioned reduction visible light communication system light source led non-linear method detailed description of the invention, it is also applied for the detailed description of the invention of the reduction nonlinear system of visible light communication system light source led provided by the invention, detailed description below of the present invention will not be described in great detail.
Shown in Fig. 7, the embodiment of the present invention also provides for a kind of reduction nonlinear system of visible light communication system light source led, and at transmitting terminal, described system includes:
Signal sequence acquiring unit 101: for obtaining signal sequence to be sent；
Selected mapping method unit 102: for described signal sequence being processed based on selected mapping method algorithm, obtain one group of multi-carrier signal sequence that peak-to-average power ratio is minimum；
Labelled sequence generates unit 103: for described multi-carrier signal sequence is converted to serial signal, and generate labelled sequence one group identical with described serial signal length；
First can recover clipping unit 104: if for the amplitude of described serial signal more than LED saturation threshold value, then more than the multi-carrier signal of LED saturation threshold value amplitude is multiplied by predistortion coefficient of compressibility, and in labelled sequence correspondence position assignment 1.
The reduction nonlinear system of visible light communication system light source led described in the embodiment of the present invention, utilizes selected mapping method algorithm that the signal sequence to be sent got is processed, and obtains one group of multi-carrier signal sequence that peak-to-average power ratio is minimum；Described multi-carrier signal sequence is converted to serial signal, and generates labelled sequence one group identical with described serial signal length；If the amplitude of described serial signal is more than LED saturation threshold value, then amplitude is multiplied by predistortion coefficient of compressibility more than the multi-carrier signal of LED saturation threshold value, and in labelled sequence correspondence position assignment 1 (margining amplitude technique can be recovered), ensure that described serial signal normally exports within the scope of LED linear, so, utilize selected mapping method algorithm and margining amplitude technique can be recovered in phase and amplitude two, multi-carrier signal amplitude range be controlled, it is made to transmit within the scope of LED linear, amplitude multi-carrier signal is overcome to transmit the non-linear effects suffered in light source led, thus eliminating the signal distortion that LED nonlinear characteristic causes, the communication system possessing light source led is made to obtain higher reliability, ensure the transmission quality of communication system.
In the detailed description of the invention of the aforementioned reduction nonlinear system of visible light communication system light source led, further, described selected mapping method unit includes:
Multiplier module, for a group phase rotation coefficient sequence generated based on selected mapping method algorithm being multiplied with described signal sequence respectively, obtains a group selection mapping signal sequence；
Inverse transform module, for described a group selection mapping signal sequence is carried out inverse fast fourier transform respectively, obtains a group multi-carrier signal sequence；
Acquisition module, for, from described a group multi-carrier signal sequence, obtaining one group of multi-carrier signal sequence that peak-to-average power ratio is minimum.
In the detailed description of the invention of the aforementioned reduction nonlinear system of visible light communication system light source led, further, at transmitting terminal, described system also includes:
Second can recover clipping unit: if for the amplitude of described serial signal less than LED saturation threshold value, then correspondence position assignment 0 in labelled sequence.
In the detailed description of the invention of the aforementioned reduction nonlinear system of visible light communication system light source led, further, at receiving terminal, described system includes:
Recovery unit: the signal for receiving terminal is received carries out amplitude limit recovery；
Described recovery unit includes:
Detection module, for detecting to the received signal at receiving terminal；
Amplitude limit recovers module, if the mark value for detecting in labelled sequence is 1, then the reception signal of correspondence position and predistortion coefficient of compressibility is divided by and carries out amplitude limit recovery；
Described amplitude limit recovers module, if the mark value being additionally operable to detect in labelled sequence is 0, then the reception signal of correspondence position remains unchanged.
In the detailed description of the invention of the aforementioned reduction nonlinear system of visible light communication system light source led, further, at receiving terminal, described system also includes:
Phase rotation coefficient acquiring unit: for obtaining one group of phase rotation coefficient sequence minimum in a group phase rotation coefficient sequence that selected mapping method algorithm generates；
Converter unit, is used for the signal after being recovered by amplitude limit after fast Fourier transform divided by described minimum phase rotation coefficient sequence.
The above is 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 principle of the present invention; can also making some improvements and modifications, these improvements and modifications also should be regarded as protection scope of the present invention.
Claims (10)
1. one kind is reduced visible light communication system light source led non-linear method, it is characterised in that including:
Obtain signal sequence to be sent；
Based on selected mapping method algorithm, described signal sequence is processed, obtain one group of multi-carrier signal sequence that peak-to-average power ratio is minimum；
Described multi-carrier signal sequence is converted to serial signal, and generates labelled sequence one group identical with described serial signal length；
If the amplitude of described serial signal is more than LED saturation threshold value, then amplitude is multiplied by predistortion coefficient of compressibility more than the multi-carrier signal of LED saturation threshold value, and in labelled sequence correspondence position assignment 1.
2. reduction visible light communication system light source led non-linear method according to claim 1, it is characterised in that described based on selected mapping method algorithm, described signal sequence is processed, the one group of multi-carrier signal sequence obtaining peak-to-average power ratio minimum includes:
The a group phase rotation coefficient sequence generated based on selected mapping method algorithm is multiplied with described signal sequence respectively, obtains a group selection mapping signal sequence；
Described a group selection mapping signal sequence is carried out inverse fast fourier transform respectively, obtains a group multi-carrier signal sequence；
From described a group multi-carrier signal sequence, obtain one group of multi-carrier signal sequence that peak-to-average power ratio is minimum.
3. reduction visible light communication system light source led non-linear method according to claim 1, it is characterised in that described method also includes:
If the amplitude of described serial signal is less than LED saturation threshold value, then correspondence position assignment 0 in labelled sequence.
4. reduction visible light communication system light source led non-linear method according to claim 1, it is characterised in that described method also includes:
The signal that receiving terminal is received carries out amplitude limit recovery；
The described signal that receiving terminal is received carries out amplitude limit and recovers to include:
Detect to the received signal at receiving terminal；
If the mark value detected in labelled sequence is 1, then the reception signal of correspondence position and predistortion coefficient of compressibility is divided by and carries out amplitude limit recovery；
If the mark value detected in labelled sequence is 0, then the reception signal of correspondence position remains unchanged.
5. reduction visible light communication system light source led non-linear method according to claim 4, it is characterised in that the described signal that receiving terminal is received includes after carrying out amplitude limit recovery:
Obtain one group of phase rotation coefficient sequence minimum in a group phase rotation coefficient sequence that selected mapping method algorithm generates；
By amplitude limit recover after signal after fast Fourier transform divided by described minimum phase rotation coefficient sequence.
6. one kind is reduced the nonlinear system of visible light communication system light source led, it is characterised in that at transmitting terminal, described system includes:
Signal sequence acquiring unit: for obtaining signal sequence to be sent；
Selected mapping method unit: for described signal sequence being processed based on selected mapping method algorithm, obtain one group of multi-carrier signal sequence that peak-to-average power ratio is minimum；
Labelled sequence generates unit: for described multi-carrier signal sequence is converted to serial signal, and generate labelled sequence one group identical with described serial signal length；
First can recover clipping unit: if for the amplitude of described serial signal more than LED saturation threshold value, then more than the multi-carrier signal of LED saturation threshold value amplitude is multiplied by predistortion coefficient of compressibility, and in labelled sequence correspondence position assignment 1.
7. the reduction nonlinear system of visible light communication system light source led according to claim 6, it is characterised in that described selected mapping method unit includes:
Multiplier module, for a group phase rotation coefficient sequence generated based on selected mapping method algorithm being multiplied with described signal sequence respectively, obtains a group selection mapping signal sequence；
Inverse transform module, for described a group selection mapping signal sequence is carried out inverse fast fourier transform respectively, obtains a group multi-carrier signal sequence；
Acquisition module, for, from described a group multi-carrier signal sequence, obtaining one group of multi-carrier signal sequence that peak-to-average power ratio is minimum.
8. the reduction nonlinear system of visible light communication system light source led according to claim 6, it is characterised in that at transmitting terminal, described system also includes:
Second can recover clipping unit: if for the amplitude of described serial signal less than LED saturation threshold value, then correspondence position assignment 0 in labelled sequence.
9. the reduction nonlinear system of visible light communication system light source led according to claim 6, it is characterised in that at receiving terminal, described system includes:
Recovery unit: the signal for receiving terminal is received carries out amplitude limit recovery；
Described recovery unit includes:
Detection module, for detecting to the received signal at receiving terminal；
Amplitude limit recovers module, if the mark value for detecting in labelled sequence is 1, then the reception signal of correspondence position and predistortion coefficient of compressibility is divided by and carries out amplitude limit recovery；
Described amplitude limit recovers module, if the mark value being additionally operable to detect in labelled sequence is 0, then the reception signal of correspondence position remains unchanged.
10. the reduction nonlinear system of visible light communication system light source led according to claim 9, it is characterised in that at receiving terminal, described system also includes:
Phase rotation coefficient acquiring unit: for obtaining one group of phase rotation coefficient sequence minimum in a group phase rotation coefficient sequence that selected mapping method algorithm generates；
Converter unit, is used for the signal after being recovered by amplitude limit after fast Fourier transform divided by described minimum phase rotation coefficient sequence.
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