CN107864423A - A kind of visible light communication wireless sound box based on OFDM - Google Patents
A kind of visible light communication wireless sound box based on OFDM Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2420/00—Details of connection covered by H04R, not provided for in its groups
- H04R2420/03—Connection circuits to selectively connect loudspeakers or headphones to amplifiers
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Abstract
The invention belongs to visible light communication field, a kind of visible light communication wireless sound box based on OFDM is specifically provided, to solve the problems, such as that the transmission rate of conventional wireless audio amplifier is slow, it is too high with cost to be easily disturbed, and the availability of frequency spectrum is low and the problem of easily influenceed by multipath effect.Visible light communication wireless sound box of the invention based on OFDM, transmitting terminal include：Audio signal source, source signal processing module, OFDM modulation modules, D/A converter module and LED driver circuit module, the receiving terminal being sequentially connected include：Photoelectric conversion module, analog-to-digital conversion module, OFDM demodulation module, reception signal processing module and the audio amplifier being sequentially connected.The present invention takes into account communication while illumination, harmless in the absence of electromagnetic radiation, without radio-frequency spectrum certification, it is not easy to form interference with other communication technologys, and has stronger anti-multipath effect interference performance, intersymbol interference is reduced, improves transmission rate and band efficiency.
Description
Technical field
The invention belongs to visible light communication field, and in particular to a kind of visible light communication wireless sound box based on OFDM.
Background technology
Electronic product in life is changed into wireless from wired more and more, from being wirelessly used as solution, its purpose
It is that and is free to pan；And conventional audio amplifier is when in use, due to the limitation of wire, its audio amplifier can not depart from sound
The certain limit in source, and enter the arrangement of row conductor indoors, not only trouble but also unsightly.
The wireless technology that traditional wireless sound box uses mainly includes the technologies such as FM, infrared, bluetooth, WiFi, 2.4G；So
And in these technologies, FM technologies are limited by transmission bandwidth, and universal tonequality is bad, and are easily interfered, it may appear that string
Frequency phenomenon, cause stability not good enough, confidentiality is poor；Wireless infrared transmitting bandwidth is high, but transmission power requires higher, and is easily hidden
The influence of thing is covered, causes audio signal not transmit；Bluetooth data transmission amount is small, has influence on the broadcasting of high quality audio；2.4G
There is delay, it is bad to the experience that plays immediately；WiFi power consumptions are larger, expensive hardware, and cost is too high.
Existing visible ray wireless sound box is usually using ON-OFF keying modulation or pulse width modulation, because system is set
Meter is simple, and can not efficiently utilize LED bandwidth, causes traffic rate to reduce, and the availability of frequency spectrum reduces；On the other hand, it is seen that
For light during space propagation, its transmission path also diffuses path except direct path, so, signal is sent from LED,
Signal is received to receiving terminal photodetector, there can be a plurality of optical signal path, so as to cause meeting between the signal received
The problem of interfering, i.e., existing visible ray wireless sound box can be influenceed by multipath effect, cause its antijamming capability weak.
The content of the invention
It is an object of the invention to the technological deficiency for above-mentioned existing wireless sound box, there is provided a kind of based on the visible of OFDM
Optic communication wireless sound box, to solve the problems, such as that the transmission rate of conventional wireless audio amplifier is slow, it is too high with cost to be easily disturbed, and
The problem of availability of frequency spectrum is low and is easily influenceed by multipath effect.In order to achieve the above object, the technical solution adopted by the present invention is：
A kind of visible light communication wireless sound box based on OFDM, its transmitting terminal include：Audio signal source, D/A converter module
(DAC) and LED driver circuit module, receiving terminal include：Photoelectric conversion module, analog-to-digital conversion module (ADC) and audio amplifier；Its feature
It is, transmitting terminal also includes source signal processing module and OFDM modulation modules, and receiving terminal also includes OFDM corresponding with transmitting terminal
Demodulation module and reception signal processing module；
Transmitting terminal：The audio signal source, source signal processing module, OFDM modulation modules, D/A converter module (DAC) and
LED driver circuit module is sequentially connected；Audio signal source output source audio signal, source signal processing module receive source audio letter
Number and achieve and transmitted in visible light channel, reduce interference of the channel to signal；OFDM modulation modules handle mould to source signal
The output signal of block carries out OFDM modulation, output OFDM data signal, and signal can resist the influence of multipath effect after modulation, and
And improve frequency efficiency and transmission rate；OFDM data signals after modulation are converted to analog signal and entered by D/A converter module
Row transmission；Analog signal is loaded into LED by LED driver circuit module, and driving LED carries out the space hair of audio signal
Send；
Receiving terminal：The photoelectric conversion module, analog-to-digital conversion module (ADC), OFDM demodulation module, reception signal processing mould
Block and audio amplifier are sequentially connected；Photoelectric conversion module, which is converted to the LED light signal received from space, receives analog signal (electricity
Signal)；Analog-to-digital conversion module is converted to reception data signal by analog signal is received, and is easy to handle signal；OFDM is solved
Mode transfer block will receive data signal and carry out OFDM demodulation, it is reverted to the output data of source signal processing module；Reception signal
Signal after OFDM demodulation is reverted to source audio signal by processing module, then source audio signal is sent into sound equipment, is entered by sound equipment
Row audio plays.
Further, the source signal processing module includes：Scrambling module, convolutional encoder module and the intertexture being sequentially connected
Module, wherein：
Scrambling module is used to carry out scrambling processing to source audio signal, uses generator polynomial S (x)=x7+x4+ 1 generation is pseudo-
Random code sequence, the data after scrambling enter convolutional encoder module；
Convolutional encoder module carries out convolutional encoding processing to the data after scrambling, using (2,1,7) convolutional code, after scrambling
Data carry out convolutional encoding generation two-way output data A and B：Output data A generator polynomial is S (x)=x6+x5+x3+
x2+ 1, output data B generator polynomial are S (x)=x6+x3+x2+x1+1；Two channel parallel datas of generation are converted into string again
Row data are output to interleaving block；
Interleaving block is interleaved processing to the data after convolutional encoding, by the way of two-stage intertexture；The first order interweaves
Transformation for mula is：I=(NCBPS/ 16) (k × mod16)+floor (k/16), k=0,1 ..., NCBPS- 1, wherein, before k is interweaves
Bit label, i be interweave after label, NCBPSFor the bit number of an IFFT processing；Second level interleaved transforms formula is：j
=s × floor (i/s)+(i+NCBPS-floor(16×i/NCBPS)) mods, i=0,1 ..., NCBPS- 1, wherein, j second
Bit label after level intertexture, s are the bit number divided by 2 of each sub-carrier code；Data after intertexture are sent into OFDM modulation moulds
Block.
Further, the OFDM modulation modules include：The 16QAM mapping blocks that are sequentially connected, insertion pilot module, altogether
The symmetrical module of yoke, IFFT modules plus cyclic prefix and adding window module；Wherein：
16QAM mapping blocks, input data is mapped in 16 constellation points using 4 bits as one group, and to number after mapping
According to being normalized to obtain I, Q two paths of data；
Pilot module is inserted, carries out the insertion of pilot tone respectively to I, Q two paths of data；
Symmetrical module is conjugated, I, Q two paths of data after insertion pilot tone be conjugated symmetrically, merge I, Q two paths of data
For a circuit-switched data, it is easy to transmissions of the LED to signal；
IFFT modules,, will so as to realize OFDM subchannel distribution for signal to be carried out into fast fourier inverse transformation
Data are modulated on each subcarrier of channel, improve the availability of frequency spectrum and transmission rate；
Add cyclic prefix and adding window module, data carry out adding cyclic prefix and windowing process after changing to IFFT, for disappearing
Except intersymbol interference (ISI) and inter-sub-carrier interference (ICI).
Further, the OFDM demodulation module includes：Going of being sequentially connected and removes window module, FFT at cyclic prefix
Module, go to be conjugated symmetrical module, go pilot module and 16QAM inverse mapping modules；Each submodule is the OFDM modulation modules
The inverse process of internal each submodule, so as to realize the OFDM demodulation of signal.
The signal processing module that receives includes：De-interleaving block, Viterbi decoding modules and the descrambling mould being sequentially connected
Block；Each submodule is the inverse process of each submodule of source signal processing module, so as to realize source audio signaling protein14-3-3.
Beneficial effects of the present invention are：
1st, the present invention provides the visible light communication wireless sound box based on OFDM, takes into account communication while illumination, is not present
Electromagnetic radiation, it is harmless, Contamination of Electromagnetic Wave will not be caused, without radio-frequency spectrum certification, is not easy with other communication technologys
Interference is formed, and equipment is simple, and cost is low；
2nd, by scrambling, convolutional encoding and interleaving block, communication performance stabilization is improved, makes signal be not easy to be disturbed.
3rd, using symmetrical module is conjugated, conversion of I, Q two paths of data to a circuit-switched data is realized, so as to suitable for the strong of LED
Degree modulation requires；
4th, modulated using OFDM, make the availability of frequency spectrum high, transmission rate is fast, is highly resistant to multipath effect and signal is transmitted
Influence, reduce the bit error rate；
5th, easy to use and flexible, sound equipment position can be adjusted according to the actual requirements.
Brief description of the drawings
Fig. 1 is the system architecture diagram of the visible light communication wireless sound box of the invention based on OFDM.
Fig. 2 is the detailed block diagram of transmitting terminal FPGA data process part in the embodiment of the present invention.
Fig. 3 is the detailed block diagram of receiving terminal FPGA data process part in the embodiment of the present invention.
Fig. 4 is 16QAM constellation mapping rule figures in the embodiment of the present invention.
Embodiment
Below in conjunction with accompanying drawing, technical solution of the present invention is clearly and completely described, it is clear that described implementation
Example only part of the embodiment of the present invention, rather than whole embodiments；The embodiment described by reference to accompanying drawing is example
Property, it is only used for explaining the present invention, and be not considered as limiting the invention.
The present embodiment provides a kind of visible light communication wireless sound box based on OFDM, its system architecture diagram as shown in figure 1,
Its transmitting terminal includes：The audio signal source 101 that is sequentially connected, source signal processing module 102, OFDM modulation modules 103, digital-to-analogue turn
Change the mold block (DAC) 104 and LED driver circuit module 105；Its receiving terminal includes：The photoelectric conversion module 106 that is sequentially connected,
OFDM demodulation module 107, reception signal processing module 108, analog-to-digital conversion module (DAC) 109 and audio amplifier 110；In the present embodiment,
Source signal processing module 102, OFDM modulation modules 103, OFDM demodulation module 107 and reception signal processing module 108 are by FPGA
To complete data processing；
The input of source signal processing module 102 is connected with the output end of audio signal source 101, source signal processing module
102 are handled the output signal of audio signal source 101, the audio signal after processing is uploaded suitable for visible light channel again
It is defeated, reduce interference of the channel to signal；The output end of the input termination source signal processing module 102 of OFDM modulation modules 103,
OFDM modulation modules 103 carry out OFDM modulation to the output signal of source signal processing module, enable modulation signal resist it is more
The influence of footpath effect, and improve frequency efficiency and transmission rate；DAC module 104 turns the OFDM data signals after modulation
Analog signal is changed to be transmitted；Analog signal after LED driver circuit module 105 changes DAC module 104 is loaded into LED
On lamp, the space that driving LED carries out audio signal is sent；
The LED light signal received from space is converted to electric signal by photoelectric conversion module 106, is then fed into ADC moulds
The input of block 107；The analog signal that photoelectric conversion module exports is converted to data signal by ADC 107, is easy to signal
Handled；Data signal after OFDM demodulation module 108 changes ADC 107 carries out OFDM demodulation, it is reverted to source
The output data of signal processing module 102；Reception signal processing module 109 is handled the signal after OFDM demodulation, makes it
Original audio signal is reverted to, then the signal is sent into sound equipment 110, audio broadcasting is carried out by sound equipment 110.
As shown in Fig. 2 it is the detailed block diagram of the wireless sound box transmitting terminal FPGA data process part, source signal
Processing module 102 and OFDM modulation modules 103 are realized with FPGA；Wherein, source signal processing module 102 includes what is be sequentially connected
Scrambling module 201, convolutional encoder module 102 and interleaving block 103；Audio signal source 101 produces original audio serial code stream, i.e.,
Original audio signal；
Scrambling module 201 carries out scrambling processing to original audio serial code stream, uses generator polynomial S (x)=x7+x4+1
Pseudo-random code sequence is generated, its principle is to generate a scrambler scram with FPGA, and it is the register of 7, sets scrambler
Initial value is scramble [6:0]=2 ' b101_1101, scramble [3] and scramble [6] progress XORs are handled to obtain
One output valve scramble_out, it send scramble the 6th lt one, then by scramble_out into scramble
Lowest order, wait next XOR to handle；Scramble_out is flowed into the original audio serial data bitstream inputted simultaneously
Row XOR, the data input after being scrambled, the data after scrambling enter convolutional encoder module 202；
Convolutional encoder module 202 carries out convolutional encoding processing to the data after scrambling, using (2,1,7) convolutional code, i.e. code
A length of 2 bit, information word are 1 bit, constraint length 7, correspond to code check R=1/2；Data after scrambling are subjected to convolutional encoding
Generate two-way output data A and B：Output data A generator polynomial is S (x)=x6+x5+x3+x2+ 1, output data B life
It is S (x)=x into multinomial6+x3+x2+x1+1；Two channel parallel datas of generation are converted into serial data again and are output to intertexture mould
Block 203；
Interleaving block 203 is interleaved processing to the data after convolutional encoding, by the way of two-stage intertexture；The first order is
Ensure that adjacent coded-bit is mapped on non-conterminous subcarrier, specific transformation for mula is
I=(NCBPS/ 16) (k × mod16)+floor (k/16), k=0,1 ..., NCBPS-1 (1-1)
Wherein, k be interweave before bit label, i be interweave after label, NCBPSThe bit number handled for an IFFT,
Here value 192；Mod is complementation computing, and floor is to zero rounding operation；When hardware is realized, FPGA a piece of twoport is used
Memory blocks of the RAM as whole module, the generation of write address is carried out by above-mentioned formula (1-1), it is from 0 address then to read address
Start automatic plus 1 sequential system, the data of write-in are read with this sequential system, so as to complete the intertexture of the first order；The second level
Intertexture be to ensure that adjacent coded-bit is respectively mapped to the important and backseat of planisphere, its transformation for mula is
J=s × floor (i/s)+(i+NCBPS-floor(16×i/NCBPS)) mods, i=0,1 ..., NCBPS-1 (1-2)
Wherein, j be the second level interweave after data label, s be each sub-carrier code bit number divided by 2, subcarrier
Coded system is 16QAM, and corresponding sub-carrier code bit number is 4 bits, so s=2；When hardware is realized, one piece of capacity is used
The memory cell to interweave for 24bit dual port RAM as the second level, according to formula (1-2), before function that it is corresponding to realize is
12bit data are constant, and the rear 12bit adjacent two bits of data exchange position, and the data for finally obtaining interleaving block 203 are defeated
Go out.Data after intertexture are sent into OFDM modulation modules 103.
From figure 2 it can be seen that OFDM modulation modules 103 include 16QAM mapping blocks 204, insertion pilot module 205,
It is conjugated symmetrical module 206, IFFT conversion modules 207 and adds cyclic prefix and adding window module 208；
Data after intertexture are carried out constellation mapping by 16QAM mapping blocks 204, by the serial data bit stream of input with every
4bit is one group, carries out constellation mapping, and its mapping ruler is as shown in Figure 4；After the completion of mapping, in order that the symbol after mapping has one
The mean power of sample, it is necessary to mapped data is normalized, the output data after will mapping multiplied by with
Thus obtain I, Q two paths of data after 16QAM mappings；
I, Q two paths of data that insertion pilot module 205 exports 16QAM mapping blocks 204 carry out the insertion of pilot tone respectively；
By every 48 one group of I roads (or Q roads) data of input, rear 24 data are mapped to IFFT 1~6,8~20,22~26 ends
On mouth, wherein 7 ports and 21 ports insertion pilot tone；Preceding 24 data are mapped to 38~42,44~56,58~63 ports again
On, wherein 43 ports and 57 ports insertion pilot tone；The total ports of IFFT are 64, then remaining 0 port, 27~37 ports are set to 0；This
Sample just completes the insertion of pilot tone；
It is conjugated symmetrical module 206 by I, Q two paths of data after inserting pilot tone be conjugated symmetrically, becomes I, Q two paths of signals
For real signal all the way, carry out data transmission so as to be loaded into LED；Data after being conjugated symmetrically are sent into IFFT conversion
Module 207；
IFFT conversion modules 207 carry out IFFT conversion (fast fourier inverse transformation) to data, by instantiating FPGA's
IFFT IP kernels, be one group of carry out IFFT conversion by data every 64 of the conjugation of input after symmetrical, so as to realize frequency domain data to
The conversion of time-domain signal；64 data symbols are transformed on 64 sub-channels of visible light channel respectively, improved visible
The band efficiency and transmission rate of optical channel；The data after conversion are sent into again and add cyclic prefix and adding window module 208；
Cyclic prefix and adding window module 208 is added to carry out adding cyclic prefix and windowing process to the data after IFFT conversion；For
Elimination intersymbol interference (ISI) crosstalk (ICI) between subcarrier, cyclic prefix addition processing is first carried out, after IFFT is converted
The data duplication of rear 1/4 length of 64 serial datas is previously formed prefix to 64 data, then with the addition of cyclic prefix
Data length afterwards reaches 80, so as to realize the purpose for eliminating ISI and ICI；And then 80 data are carried out at adding window
Reason, frequently with window function be raised cosine, it is defined as follows：
Wherein, β is roll-off factor, TsFor the length before adding window, and the symbol lengths after adding window are (1+ β) Ts, so as to allow
Overlapped region is there are between adjacent-symbol so that power spectral density of the OFDM symbol outside bandwidth declines more
It hurry up, improve antijamming capability；T in the systems=4.0 μ s, β Ts=50ns, corresponding β=1/80, system data is discrete time pair
The data answered, then windowed function be correspondingly changed into
It is embodied as hardware, by the 1st data of 80 data after insertion cyclic prefix and the 17th data difference
Divided by the 1st data of 2 80 data after addition obtains adding window, that is, complete windowing operation；
Data after adding cyclic prefix and adding window module 208, complete by data encoding and modulated process based on FPGA, will
Its data signal exported input DAC module 104, realizes conversion of the data signal to analog signal；Analog signal after conversion
It is sent to LED driver circuit module.
LED driver circuit module 105 turns current segment and constant current driver circuit for LED part including voltage；Because LED is used
The luminous intensity of intensity modulated mode, i.e. LED is proportional with driving its luminous electric current, so need to be by DAC module 104
The voltage analog signal of output is converted to current signal, reloads in LED；Simultaneously in order that LED is normal, transmission is realized
It can be illuminated during signal, it is necessary to add a constant-current source, LED is in its workspace normal luminous for driving；By two Signal averagings in
In LED, you can realize the transmission of signal and the illumination of LED.
So far the design of the wireless sound box transmitting terminal part is completed.
Photoelectric conversion module 106 converts light to voltage signal by what is received, is re-fed into ADC 107；The module
Including four PIN photodetector, pre-amplification circuit, bandpass amplifier and main amplifier parts；Wherein, PIN Photoelectric Detections
Device detection space in can be by light, it will be seen that light is converted to current signal by photoelectric effect；Pre-amplification circuit is by PIN photoelectricity
Current signal is converted to voltage signal caused by detector, is easy to signal transacting, while signal is amplified；Bandpass filter
Filter out the low frequency signal and High-frequency Interference in the treated signal of pre-amplification circuit；Filtered signal is sent into main amplifier
In, signal is enlarged into the voltage signal that suitable ACD module 107 handles；After ACD module 107 handles photoelectric conversion module 106
Analog voltage signal be converted to data signal be sent into FPGA processing.
As shown in figure 3, it is the detailed block diagram of the wireless sound box receiving terminal FPGA data process part, OFDM solutions
Mode transfer block 108 and reception signal processing module 109 realize that the two modules correspond to transmitting terminal OFDM modulation modules with FPGA
103 and the inverse process of source signal processing module 102；OFDM demodulation module 108 includes removing cyclic prefix and removes window module 308, FFT
Conversion module 307, go to be conjugated symmetrical module 306, go pilot module 305 and 16QAM inverse mappings module 304.
Data signal feeding after ADC 107 is changed removes cyclic prefix and goes window module 308, and signal follow
Ring prefix and window is gone to handle；Hardware is embodied as every 80 one group of the data of input, 16 before removal, 64 significant figures after leaving
According to；64 data are sent into FFT module 307 and carry out Fast Fourier Transform (FFT), complete time-domain signal to frequency-region signal
Conversion；Data after FFT are sent into and go to be conjugated in symmetrical module 306, I, Q two-way letter will be converted to by real signal all the way
Number；This two paths of signals is sent into and goes pilot module 305, and the module removes 4 pilot tones and 12 numbers set to 0 in 64 data of two-way
According to finally obtaining the data after 48 16QAM of two-way mappings；The data after pilot tone are gone to be sent into 16QAM module inverse mapping modules
304, data are the data after intertexture by the inverse mapping of 16QAM planispheres by the module；To the process of this completion OFDM demodulation.
From figure 3, it can be seen that reception signal processing module 109 includes de-interleaving block 303, Veterbi decoding modules
302 and descrambling module 301；Data after OFDM demodulation are sent into de-interleaving block 303, and the module is still two-stage deinterleaving, the
One-level deinterleaves the inverse process to interweave for the second level, and the second level deinterleaves the inverse process to interweave for the first order；Hardware realization is as follows,
First order deinterleaving every 24 by data is one group, and preceding 12 holdings are constant, latter 12 adjacent data exchange positions.The second level
Deinterleaving transformation for mula is：
K=16 × i- (NCBPS-1)floor(16×i/NCBPS) i=0,1 ..., NCBPS-1 (1-5)
The formula is that write address produces formula, reads address and is produced for sequential system, so, just completes deinterleaving process；
Veterbi decoding modules 302 carry out the decoding of convolutional code to the data after deinterleaving, here by instantiating FPGA's
Veterbi decodes IP kernel to complete decoding process；Data after decoding are sent into descrambling module 301, descrambling module and scrambling mould
Block has identical pseudo-random sequence generating mode, i.e. S (x)=x7+x4+1；Descrambled by this pseudo-random sequence, so as to obtain
Original audio signal, the signal is sent into audio amplifier 110, it is possible to carry out the broadcasting of audio；
So far, the design for so far completing the wireless sound box receiving terminal part is completed.
The foregoing is only a specific embodiment of the invention, any feature disclosed in this specification, except non-specifically
Narration, can alternative features equivalent by other or with similar purpose replaced；Disclosed all features or all sides
Method or during the step of, in addition to mutually exclusive feature and/or step, can be combined in any way.
Claims (5)
1. a kind of visible light communication wireless sound box based on OFDM, its transmitting terminal include：Audio signal source, D/A converter module
(DAC) and LED driver circuit module, receiving terminal include：Photoelectric conversion module, analog-to-digital conversion module (ADC) and audio amplifier；Its feature
It is, transmitting terminal also includes source signal processing module and OFDM modulation modules, and receiving terminal also includes OFDM corresponding with transmitting terminal
Demodulation module and reception signal processing module；
Transmitting terminal：The audio signal source, source signal processing module, OFDM modulation modules, D/A converter module (DAC) and LED
Drive circuit module is sequentially connected；Audio signal source output source audio signal, source signal processing module receive source audio signal, simultaneously
Achieve and transmitted in visible light channel；OFDM modulation modules the output signal of source signal processing module is carried out OFDM modulation,
Output OFDM data signal；OFDM data signals after modulation are converted to analog signal and are transmitted by D/A converter module；LED
Analog signal is loaded into LED by drive circuit module, and the space that driving LED carries out audio signal is sent；
Receiving terminal：The photoelectric conversion module, analog-to-digital conversion module (ADC), OFDM demodulation module, reception signal processing module and
Audio amplifier is sequentially connected；The LED light signal received from space is converted to and receives analog signal (telecommunications by photoelectric conversion module
Number)；Analog-to-digital conversion module is converted to reception data signal by analog signal is received；OFDM demodulation module is entered data signal is received
Row OFDM demodulation, it is set to revert to the output data of source signal processing module；Reception signal processing module is by after OFDM demodulation
Signal reverts to source audio signal, then source audio signal is sent into sound equipment, and audio broadcasting is carried out by sound equipment.
2. the visible light communication wireless sound box based on OFDM as described in claim 1, it is characterised in that the source signal handles mould
Block includes：Scrambling module, convolutional encoder module and the interleaving block being sequentially connected, wherein：
Scrambling module is used to carry out scrambling processing to source audio signal, uses generator polynomial S (x)=x7+x4+ 1 generation pseudorandom
Code sequence, the data after scrambling enter convolutional encoder module；
Convolutional encoder module carries out convolutional encoding processing to the data after scrambling, using (2,1,7) convolutional code, by the number after scrambling
Two-way output data A and B are generated according to convolutional encoding is carried out：Output data A generator polynomial is S (x)=x6+x5+x3+x2+ 1,
Output data B generator polynomial is S (x)=x6+x3+x2+x1+1；Two channel parallel datas of generation are converted into serial number again
According to being output to interleaving block；
Interleaving block is interleaved processing to the data after convolutional encoding, by the way of two-stage intertexture；First order interleaved transforms
Formula is：I=(NCBPS/ 16) (k × mod16)+floor (k/16), k=0,1 ..., NCBPS- 1, wherein, k is the ratio before interweaving
Special label, i be interweave after label, NCBPSFor the bit number of an IFFT processing；Second level interleaved transforms formula is：J=s ×
floor(i/s)+(i+NCBPS-floor(16×i/NCBPS)) mods, i=0,1 ..., NCBPS- 1, wherein, j interweaves for the second level
Bit label afterwards, s are the bit number divided by 2 of each sub-carrier code；Data after intertexture are sent into OFDM modulation modules.
3. the visible light communication wireless sound box based on OFDM as described in claim 1, it is characterised in that the OFDM modulation modules
Including：The 16QAM mapping blocks that are sequentially connected, insertion pilot module, the symmetrical module of conjugation, IFFT modules plus cyclic prefix and
Adding window module；Wherein：
16QAM mapping blocks, input data is mapped in 16 constellation points using 4 bits as one group, and mapped data is entered
Row normalized obtains I, Q two paths of data；
Pilot module is inserted, carries out the insertion of pilot tone respectively to I, Q two paths of data；
Symmetrical module is conjugated, I, Q two paths of data after insertion pilot tone be conjugated symmetrically, I, Q two paths of data is merged into one
Circuit-switched data；
IFFT modules, for signal to be carried out into fast fourier inverse transformation；
Add cyclic prefix and adding window module, data carry out adding cyclic prefix and windowing process after changing to IFFT, for blanking code
Between crosstalk (ISI) and inter-sub-carrier interference (ICI).
4. the visible light communication wireless sound box based on OFDM as described in claim 2, it is characterised in that the OFDM demodulation module
Including：Be sequentially connected remove cyclic prefix and go window module, FFT module, go to be conjugated symmetrical module, go pilot module and
16QAM inverse mapping modules；Each submodule is the inverse process of each submodule inside the OFDM modulation modules, so as to realize signal
OFDM demodulation.
5. the visible light communication wireless sound box based on OFDM as described in claim 3, it is characterised in that described to receive signal transacting
Module includes：De-interleaving block, Viterbi decoding modules and the descrambling module being sequentially connected；Each submodule is the source letter
The inverse process of number each submodule of processing module, so as to realize source audio signaling protein14-3-3.
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