CN103457661A - LED array visible light communication system and method - Google Patents
LED array visible light communication system and method Download PDFInfo
- Publication number
- CN103457661A CN103457661A CN2013104078212A CN201310407821A CN103457661A CN 103457661 A CN103457661 A CN 103457661A CN 2013104078212 A CN2013104078212 A CN 2013104078212A CN 201310407821 A CN201310407821 A CN 201310407821A CN 103457661 A CN103457661 A CN 103457661A
- Authority
- CN
- China
- Prior art keywords
- ofdm
- signal
- subcarrier
- dft
- frequency domain
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Landscapes
- Mobile Radio Communication Systems (AREA)
- Optical Communication System (AREA)
Abstract
The invention discloses an LED array visible light communication system based on DFT-S OFDM and an LED array visible light communication method. An LED light source composed of a plurality of LED chips serves as the emitting end, and the LED chips are independently driven to form LED array emitting systems which do not disturb each other. The DFT-S OFDM modulation mode is adopted by each LED emitter, the LED emitters occupy different OFDM frequency band resources respectively, circumference conjugate symmetry is applied to OFDM frequency domain subcarriers to guarantee real number property of OFDM base band data, and a centralized DFT-S OFDM mode and a staggered DFT-S OFDM mode are applied to the visible light communication system. The DFT-S technology applied to the LED array visible light communication system based on DFT-S OFDM and the LED array visible light communication method can obviously restrain the peak-to-average power ratio of the visible light communication system, obvious frequency domain diversity gains are acquired in the aspect of bit error rate performance, and the LED array emitting structure protects system transmission ratio against effect.
Description
Technical field
The present invention relates to the technical field of visible light communication, relate in particular to a kind of LED array visible light communication system and method thereof based on DFT-S OFDM.
Background technology
In recent years, visible light communication has become the popular domain in radio communication.With the conventional wireless telecommunication, compare, visible light communication is a kind of than the radio wave communication mode of green health more, and it also has abundanter frequency spectrum resource, higher confidentiality and without advantages such as licences simultaneously.
Indoor visible light communication research is devoted to the high speed wireless data transmission is combined with the general room illumination.For enough intensities of illumination are provided, existing indoor LED illumination light source majority all is comprised of a plurality of LED chips.Each LED chip by separate modulation and light source of driving, can form a LED array system at transmitting terminal, transmits different data flow simultaneously.
In order to improve the transmission rate of visible light communication system, orthogonal frequency division multiplexi (the English OFDM that is called for short) is introduced in visible light communication.Except the availability of frequency spectrum is high and can be effectively to anti-ISI, the visible ray ofdm system has it to be different from the peculiar property of common OFDM.Because visible light communication is taked the method for intensity modulated and direct-detection usually, visible ray OFDM baseband signal must meet the requirement of arithmetic number character.Existing visible ray OFDM scheme mainly contains the English DCO-OFDM of abbreviation of direct current biasing light OFDM() and the English ACO-OFDM of abbreviation of asymmetrical beam OFDM(), the former is easy to realize and have the higher availability of frequency spectrum, yet has reduced the effective power utilance because need on signal, superpose DC offset voltage.
Planisphere can be regarded " two-dimentional eye pattern " array of digital signal as, and the residing in the drawings position of symbol has rational restriction or decision boundaries simultaneously.The point that represents each receiving symbol is more approaching in the drawings, and signal quality is just higher.Because the figure correspondence on screen amplitude and phase place, the shape of array can be used to many defects and the distortion of analysis and definite system or channel, and helps to search its reason.In Digital Modulation, we can observe the situations such as phase shift track between the variation, noise jamming, each vector point of phase place by planisphere, pass through planisphere, we can find out the availability of frequency spectrum situation of each Vector Modulation at an easy rate, should say, the phase shift track that changes baseband signal has also just changed the spectral characteristic of modulation signal.
Height power ratio (the English PAPR that is called for short) is one of main drawback of ofdm system.In the DCO-OFDM system, too high peak-to-average force ratio not only can cause that signal nonlinear distortion occurring when the power amplifier, and the DC offset voltage that also can cause needs to superpose is excessive and greatly reduce the effective power utilance.Therefore peak-to-average force ratio is suppressed in visible light communication system and seems particularly important.In the conventional wireless telecommunication, people have proposed the method that amplitude limit, companding, selective mapping and partial sequence transmission method etc. suppress peak-to-average force ratio, yet they mostly take sacrificial system bit error rate (the English BER of abbreviation) performance or greatly increase computation complexity as cost.
Discrete fourier expansion OFDM(is hereinafter to be referred as DFT-S OFDM) be the exsertile peak-to-average force ratio inhibition of a kind of property technology, be applied to LTE up link scheme.DFT-S OFDM carries out during the FFT operation is diffused into frequency domain by symbol before OFDM modulation, does not have influence on the orthogonality of ofdm signal.By the symbol by after fast fourier transform (hereinafter to be referred as FFT) operation, by certain method of salary distribution, be arranged on the OFDM subcarrier in frequency domain, can be so that the part OFDM time-domain signal after invert fast fourier transformation (hereinafter to be referred as IFFT) conversion present single-carrier signal character, thus peak-to-average force ratio reduced.Yet due to the visible ray channel, baseband signal there is the requirement of real number, traditional DFT-S structure has not been suitable in visible light communication, need the improved system structure to make the DFT-S ofdm signal both meet the requirement of real number character, can reach again significant peak-to-average force ratio inhibition, also can not have influence on the performance index such as system transmission rate simultaneously.
Summary of the invention
In order to overcome the deficiencies in the prior art, the invention provides a kind of LED array visible light communication system and method thereof based on DFT-S OFDM, effectively guarantee the characteristic of visible ray baseband signal arithmetic number, can reduce significantly visible ray system peak-to-average ratio, and obtain the BER performance gain under the prerequisite of not losing any system transmission rate.
For achieving the above object, the present invention adopts following technical scheme:
A kind of LED array visible light communication system, comprise transmitting terminal and receiving terminal;
Transmitting terminal comprises DFT-S-OFMA modulator and at least one LED driver module, and described DFT-S-OFMA modulator is for the input data are carried out to the DFT-S-OFMA modulation, and the generation signal of telecommunication sends to the LED driver module; Described LED driver module is for being converted to light signal by the signal of telecommunication received.
Receiving terminal comprises PIN receiver and DFT-S-OFMA demodulator, the light signal that described PIN receiver sends for receiving transmitting terminal, and be converted to the signal of telecommunication and send to the DFT-S-OFMA demodulator; Described DFT-S-OFMA demodulator is for carrying out the DFT-S-OFMA demodulation to the signal of telecommunication received.
Transmitting terminal adopts a LED lighting source be comprised of a plurality of LED chips, and each LED chip is by separate modulation, thereby forms a plurality of LED array emission systems.Each LED transmitter has adopted Bias-Tee structure stack direct current biasing to make signal for just, and takies the OFDM frequency range different from other LED, keeps each other strict frequency orthogonal.At receiving terminal, only need a receiver receive from the light signal of LED array simultaneously and carry out a FFT conversion like this, can complete the OFDM demodulation and recover the data of each LED transmitter.
The communication means that the present invention also provides a kind of LED array visible light communication system to adopt, comprise the steps:
(1) the input data are carried out to the DFT-S-OFMA modulation, and generate the signal of telecommunication;
(2) signal of telecommunication step (1) generated is converted to light signal and sends;
(3) light signal that receiving step (2) sends is changed to the signal of telecommunication;
(4) signal of telecommunication step (3) generated carries out the DFT-S-OFMA demodulation, thus the described input data of reduction step (1).
For reducing the system peak-to-average ratio, each LED transmitter all adopts the modulator approach of DFT-S OFDM.Data symbol for after the planisphere mapping, first carry out the DFT extended operation time-domain signal be diffused in frequency domain, then be mapped to the OFDM corresponding band by certain OFDM sub-carrier distribution manner.Due to visible light communication, baseband signal is had the requirement of real number, we,, to the in addition restriction of circumference conjugation symmetry of the data structure of OFDM subcarrier in frequency domain, are about to significant character and only will be positioned over subcarrier in frequency domain first half section, and the corresponding conjugate symmetric data of filling of second half section.
Specifically, DFT-S OFDM can be divided into centralized DFT-S OFDM and alternating expression DFT-S OFDM according to the difference of sub-carrier distribution manner.Suppose that the FFT operation of DFT diffusion counts as the M point, the IFFT operation of OFDM modulation is counted as the N point, and meeting N=2QM(Q is positive integer, is an important parameter of communication system) relation.At first the symbol of centralized DFT-S pattern after to constellation mapping carry out M point FFT operation, the M point symbol of generation is assigned on the continuous N subcarrier in frequency domain of OFDM to remaining (Q-1) M subcarrier zero padding.QM+2 is to the conjugate symmetric data of filling respectively the symbol on its cross-talk of first half about QM+1 subcarrier symmetry carrier wave on N subcarrier in frequency domain.The 1st of OFDM and QM+1 subcarrier need be filled real number.And alternating expression DFT-S pattern with it difference be, symbol after M point FFT operation is started to place a significant character every Q-1 subcarrier from the some OFDM subcarrier in frequency domain of first half section, fill Q-1 between two significant characters individual zero, until QM subcarrier.For the subcarrier in frequency domain of second half section, carry out the conjugation symmetry operation identical with centralized DFT-S.
Further, step (1) comprises the steps:
(11) the FFT operation of establishing the DFT diffusion is counted as the M point, to input data { x
k, k=0,1 ..., M-1} carries out M point DFT operation, is converted into frequency-region signal { X
l, l=0,1 ..., M-1};
(12) establishing OFDM subcarrier in frequency domain number is N, the number of LED driver module is L, N OFDM subcarrier in frequency domain distributed to L LED driver module, especially, OFDM subcarrier in frequency domain N=S*L in the present invention, and S is positive integer, N OFDM subcarrier in frequency domain is averagely allocated to L LED driver module.Then frequency-region signal { the X according to the subcarrier allocation rule, step (11) obtained
l, l=0,1 ..., M-1} is mapped on N OFDM subcarrier in frequency domain, and carries out circumference conjugation symmetry arrangement and process;
(13) to the frequency-region signal { X after step (12) processing
l, l=0,1 ..., M-1} carries out N point IFFT conversion, generates OFDM time-domain signal { y
n, n=0,1 ..., N-1}, export after then before the OFDM time-domain signal, adding Cyclic Prefix;
(14) by the OFDM time-domain signal { y of step (13) output
n, n=0,1 ..., N-1} carries out exporting after digital-to-analogue conversion.
When further, step (12) adopts centralized DFT-S OFDM operation, comprise the steps:
(121) establish N OFDM subcarrier in frequency domain { y
k, k=1,2 ..., N}, distribute to L LED driver module by N OFDM subcarrier in frequency domain, at { y
k, k=1, place real number signal on two subcarriers of N/2+1};
(122) by frequency-region signal { X
l, l=0,1 ..., M-1} is mapped to OFDM subcarrier in frequency domain { y
k, k=1,2 ..., in N/2} on the continuous subcarrier of M, all the other N/2-M-1 subcarrier zero paddings;
(123) by OFDM subcarrier in frequency domain { y
k, k=N/2+2, N/2+3 ..., N} fills respectively its subcarrier about N/2+1 subcarrier symmetry { y
k, k=N/2, N/2-1 ..., the conjugate symmetric data of the symbol on 2}.
When further, step (12) adopts alternating expression DFT-S OFDM operation, comprise the steps:
(121) establish N OFDM subcarrier in frequency domain { y
k, k=1,2 ..., N}, distribute to L LED driver module by N OFDM subcarrier in frequency domain, at { y
k, k=1, place real number signal on two subcarriers of N/2+1};
(122) choose at random OFDM subcarrier in frequency domain { y
k, k=2,3 ..., a subcarrier in N/2}, be made as { y
k, k=T}, by frequency-region signal { X
l, l=0} is mapped to subcarrier { y
k, k=T} is upper, by frequency-region signal { X
l, l=1} is mapped to subcarrier { y
k, k=T+N/2M} is upper, by that analogy, and every N/2M
-1individual subcarrier shines upon once, until complete frequency-region signal { X
l, l=0,1 ..., M-1} is to OFDM subcarrier in frequency domain { y
k, k=2,3 ..., the mapping of N/2};
(123) by OFDM subcarrier in frequency domain { y
k, k=N/2+2, N/2+3 ..., N} fills respectively its subcarrier about N/2+1 subcarrier symmetry { y
k, k=N/2, N/2-1 ..., the conjugate symmetric data of the symbol on 2}.
Further, step (4) comprises the steps:
(41) signal of telecommunication step (3) sent carries out analog-to-digital conversion, obtains the front digital signal of demodulation;
(42) Cyclic Prefix in the digital signal that removal step (41) obtains, and carry out N point FFT conversion, obtain N OFDM frequency domain carrier signal;
(43) N OFDM frequency domain carrier signal step (42) obtained carried out channel estimating, and carries out the OFDM frequency domain equalization according to the channel tap coefficient of estimating;
(44) the subcarrier allocation rule that corresponding step (12) adopts, the carrier signal that step (7) is obtained is done reverse operating, takes out M effectively sub-carrier signal { X
l, l=0,1 ..., M-1}, and carry out M point IDFT operation, the final described input data of reduction step (1) { x
k, k=0,1 ..., M-1}.
Beneficial effect: (1) the present invention is by applying strict circumference conjugation symmetry constraint to OFDM subcarrier data structure, the character that the DFT-S OFDM baseband signal that has guaranteed each LED emission is real number, afterwards again by the driving circuit structure stack direct current biasing of Bias-Tee, making final baseband signal is the arithmetic number signal, thereby is applicable in visible light communication system.(2) the present invention adopts centralized DFT-S and two kinds of patterns of alternating expression DFT-S OFDM all can effectively suppress visible ray system peak-to-average ratio, and when Q increases, the performance of alternating expression DFT-S is more excellent; Simultaneously for the channel of visible ray low-pass characteristic, the system BER performance under two kinds of patterns has all obtained obvious frequency diversity gain, and wherein the gain of alternating expression DFT-S is larger.(3) the present invention is after adopting DFT-S OFDM technology, and the transmission rate of single led transmitter descends to some extent, but the structural design of launching by LED array, the message transmission rate of whole system can not be affected.But, simultaneously due to the natural LED chip with a plurality of separate modulation of LED mains lighting supply commonly used, so a kind of design is highly susceptible to realizing, and only needs a small amount of overhead aspect software and hardware.
The accompanying drawing explanation
The framework key diagram that Fig. 1 is LED array visible light communication system provided by the invention.
Fig. 2 is DFT-S OFDM technology that the present invention adopts applicating flow chart while specifically implementing.
Fig. 3 is the centralized DFT-S of DFT-S OFDM technology in the LED array emission system that the present invention adopts
OFDM sub-carrier wave distribution method example key diagram.
Fig. 4 is the alternating expression DFT-S of DFT-S OFDM technology in the LED array emission system that the present invention adopts
OFDM sub-carrier wave distribution method example key diagram.
The peak-to-average force ratio comparison diagram that Fig. 5 is centralized DFT-S OFDM of the present invention and alternating expression DFT-S ofdm system and general visible ofdm system.
The BER performance comparison figure that Fig. 6 is centralized DFT-S OFDM of the present invention and alternating expression DFT-S ofdm system and general visible ofdm system.
Embodiment
Below in conjunction with accompanying drawing, the present invention is further described.
As shown in Figure 1, in LED array visible light communication system based on DFT-S OFDM provided by the invention, transmitting terminal comprises that DFT-S-OFMA modulator and at least one LED driver module DFT-S-OFMA modulator are for the input data are carried out to the DFT-S-OFMA modulation, and the generation signal of telecommunication sends to the LED driver module; The LED driver module is for being converted to light signal by the signal of telecommunication received.
Receiving terminal comprises PIN receiver and DFT-S-OFMA demodulator, the light signal that the PIN receiver sends for receiving transmitting terminal, and be converted to the signal of telecommunication and send to the DFT-S-OFMA demodulator; The DFT-S-OFMA demodulator is for carrying out the DFT-S-OFMA demodulation to the signal of telecommunication received.
Transmitting terminal has adopted the LED lighting source be comprised of a plurality of LED chips.This LED light source met the demands has been widely used in interior lighting system, and the OSTAR LEW E2A light source of being produced as OSRAM company is arranged on a 0.25cm by four high performance lED chips
2ceramic substrate on.Each LED chip carrys out drive by the drive circuit as shown in block diagram, on the interchange real signal of the circuit structure that uses a Bias-Tee after power amplifier amplifies, the enough large direct current biasing signal of one of stack, make final visible ray baseband signal meet the arithmetic number requirement.Transmitting terminal has two to three meters far away usually to the light source distance receiver, and between LED chip, distance is very near, the signal therefore sent from each LED chip the visible ray channel of process can think identical.Due to the shared complete quadrature of OFDM frequency band of each LED transmitter, at receiving terminal, only with a receiver and an OFDM demodulation, just can recover the data that each LED sends.Receiver has specifically adopted PIN diode to add the structure of trans-impedance amplifier and voltage amplifier.
For each LED emission system independently, the present invention all adopts DFT-S OFDM technology to reduce peak-to-average force ratio, and its idiographic flow is as shown in Fig. 2 (a).This example is modulated to example with planisphere, the data symbol { x that mapping produces for planisphere
k, k=0,1 ..., M-1}, at first carry out M point DFT operation time-domain signal be converted to frequency-region signal { X
l, l=0,1 ..., M-1} meets:
Then according to the subcarrier allocation rule by { X
l, l=0,1 ..., M-1} is mapped on the OFDM subcarrier in frequency domain.Notice in figure to add the conjugate moiety operation in empty frame, again emphasized when DFT-S OFDM apply in the visible ray system and the primary structure difference of the application in the conventional wireless telecommunication.Suppose { Y
m, m=0,1 ..., N-1} means the data on an ofdm signal N subcarrier in frequency domain, the circumference conjugate symmetry is required to meet:
The 1st He
place real number signal on two subcarriers, and from
to the data and the 2nd on N subcarrier
the Data Conjugate symmetry of individual subcarrier.
According to the difference of sub-carrier distribution manner, DFT-S OFDM can be divided into centralized DFT-S and alternating expression DFT-SOFDM.Suppose that the FFT operation of DFT diffusion counts as the M point, the IFFT operation of OFDM modulation is counted as the N point, and meeting N=2QM(Q is positive integer, is an important parameter of communication system) relation.At first the symbol of centralized DFT-S pattern after to constellation mapping carry out M point FFT operation, the M point symbol of generation is assigned on the continuous N subcarrier in frequency domain of OFDM to remaining (Q-1) M subcarrier zero padding.QM+2 is to the conjugate symmetric data of filling respectively the symbol on its cross-talk of first half about QM+1 subcarrier symmetry carrier wave on N subcarrier in frequency domain.The 1st of OFDM and QM+1 subcarrier need be filled real number.And alternating expression DFT-S pattern with it difference be, symbol after M point FFT operation is started to place a significant character every Q-1 subcarrier from the some OFDM subcarrier in frequency domain of first half section, fill Q-1 between two significant characters individual zero, until QM subcarrier.For the subcarrier in frequency domain of second half section, carry out the conjugation symmetry operation identical with centralized DFT-S.
While adopting centralized DFT-S OFDM operation, comprise the steps:
(1) establish N OFDM subcarrier in frequency domain { y
k, k=1,2 ..., N}, distribute to L LED driver module by N OFDM subcarrier in frequency domain, at { y
k, k=1, place real number signal on two subcarriers of N/2+1};
(2) by frequency-region signal { X
l, l=0,1 ..., M-1} is mapped to OFDM subcarrier in frequency domain { y
k, k=2,3 ..., in N/2} on the continuous subcarrier of M, all the other N/2-M-1 subcarrier zero paddings;
(3) by OFDM subcarrier in frequency domain { y
k, k=N/2+2, N/2+3 ..., N} fills respectively its subcarrier about N/2+1 subcarrier symmetry { y
k, k=N/2, N/2-1 ..., the conjugate symmetric data of the symbol on 2}.
While adopting alternating expression DFT-S OFDM operation, comprise the steps:
(1) establish N OFDM subcarrier in frequency domain { y
k, k=1,2 ..., N}, distribute to L LED driver module by N OFDM subcarrier in frequency domain, at { y
k, k=1, place real number signal on two subcarriers of N/2+1};
(2) choose at random OFDM subcarrier in frequency domain { y
k, k=2,3 ...., a subcarrier in N/2}, be made as { y
k, k=T}, by frequency-region signal { X
l, l=0} is mapped to subcarrier { y
k, k=T} is upper, by frequency-region signal { X
l, l=1} is mapped to subcarrier { y
k, k=T+N/2M} is upper, i.e. { y
k, k=T+Q}, by that analogy, every N/2M
-1(being Q-1) individual subcarrier shines upon once, until complete frequency-region signal { X
l, l=0,1 ..., M-1} is to OFDM subcarrier in frequency domain { y
k, k=2,3 ..., the mapping of N/2};
(3) by OFDM subcarrier in frequency domain { y
k, k=N/2+2, N/2+3 ..., N} fills respectively its subcarrier about N/2+1 subcarrier symmetry { y
k, k=N/2, N/2-1 ..., the conjugate symmetric data of the symbol on 2}.
After the OFDM subcarrier distributes, signal has converted the OFDM modulation through N point IFFT, produces OFDM time domain real signal { y
n, n=0,1 ..., N-1}:
In order to resist intersymbol interference, need to before the OFDM time-domain signal produced, add again one section Cyclic Prefix (the English CP of abbreviation).The length of CP must be greater than the delay duration of visible ray channel.Deliver to the VISIBLE LIGHT EMISSION machine through digital-to-analogue conversion again, making final baseband signal by certain direct current biasing that superposes is positive real signal, thereby it is luminous to can be used to driving LED.
At receiving terminal, concrete data flow, as shown in Fig. 2 (b), is used a PIN diode receiver to complete the photosignal conversion.Because from the ofdm signal frequency domain quadrature of each LED, only use a N point FFT conversion can complete the OFDM demodulation from the LED multi-path signal.For the decline of opposing channel frequency domain selectivity, also need to carry out channel estimating, and carry out the OFDM frequency domain equalization according to the channel tap coefficient of estimating.Finally, the subcarrier in frequency domain method of salary distribution adopted according to transmitting terminal, do M effective subcarrier of anti-operation taking-up and transmitting terminal same position and do M point IDFT conversion at receiving terminal, can recover correct a certain LED signal stream.
For the subcarrier distribution condition more clearly is described, below in conjunction with Fig. 3 and Fig. 4, illustrate.DFT length M=4 in this example, OFDM carrier number N=32, therefore
four groups of solid arrows that indicate DFT mean respectively the data after the DFT conversion from different data streams.In order to cover whole OFDM frequency domain bandwidth, the LED light source that transmitting terminal is used has four LED chips, i.e. LED1 to LED4.
As shown in Figure 3, for centralized DFT-S OFDM pattern, four group codes after the DFT operation are placed on respectively the 1-4 work song carrier wave of LED1, and the 5-8 work song carrier wave of LED2, on the 13-16 work song carrier wave of the 9-12 work song carrier wave of LED3 and LED4.Remaining 12 subcarrier that mean with the black dotted lines arrow is the zero padding subcarrier.The second half section of OFDM subcarrier is according to circumference conjugate symmetry padding data correspondingly.
As shown in Figure 4, the difference of alternating expression DFT-S OFDM pattern and centralized DFT-S OFDM is, data after the DFT conversion are assigned to respectively 1,5,9, the 13 work song carrier waves of LED1,2,6,10, the 14 work song carrier waves of LED2, on 3,7,11, the 15 work song carrier waves of LED3 and 4,8,12, the 16 work song carrier waves of LED4, and other operations are identical with centralized DFT-S OFDM.
Can clearly observe, each LED transmitter of two kinds of DFT-S patterns has taken the frequency range with other LED transmitter difference OFDM, has kept each other strict frequency domain orthogonality.In addition, for each LED emission subsystem, transmission rate drops to 1/4 of original ofdm system, but the transmission rate of whole LED array emission system remains unchanged.
Below in conjunction with Fig. 5 and Fig. 6, system of the present invention and the performance of general visible ray ofdm system are compared.Especially, the sample rate of institute's comparison system is 250MHz, and the OFDM carrier number is 256, and DFT length is 32 in addition.
Fig. 5 is the comparison that the present invention carries the complementary cumulative distribution function (the English CCDF of abbreviation) between centralized DFT-S OFDM, alternating expression DFT-S OFDM and tri-systems of common OFDMA.CCDF be system peak-to-average than the possibility that reaches a certain threshold value, often be used to weigh the peak-to-average force ratio performance of ofdm system.Can see, when CCDF reaches 0.1%, the peak-to-average force ratio Performance Ratio OFDMA of centralized DFT-S OFDM will get well about 2.2dB, and alternating expression DFT-S OFDM is than the better about 0.8dB of centralized DFT-S OFDM.
Fig. 6 has compared the BER performance that the present invention puies forward centralized DFT-S OFDM, alternating expression DFT-S OFDM and tri-systems of common OFDMA.Solid line means the performance under the QPSK modulation, and dotted line means the 16QAM modulation.Can see, no matter, under QPSK or 16QAM modulation, centralized DFT-S and alternating expression DFT-S OFDM have obtained obvious BER performance and have improved, and the centralized DFT-S OFDM of the ratio of gains of alternating expression DFT-S OFDM is larger.It is mainly the frequency diversity gain because the DFT extended operation brings under the visible frequency selective channel that this performance improves.
The above is only the preferred embodiment of the present invention; be noted 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 LED array visible light communication system, is characterized in that: comprise transmitting terminal and receiving terminal;
Described transmitting terminal comprises DFT-S-OFDM modulator and at least one LED driver module, and described DFT-S-OFDM modulator is for the input data are carried out to the DFT-S-OFDM modulation, and the generation signal of telecommunication sends to the LED driver module; Described LED driver module is for being converted to light signal by the signal of telecommunication received;
Described receiving terminal comprises PIN receiver and DFT-S-OFDM demodulator, the light signal that described PIN receiver sends for receiving transmitting terminal, and be converted to the signal of telecommunication and send to the DFT-S-OFDM demodulator; Described DFT-S-OFMA demodulator is for carrying out the DFT-S-OFDM demodulation to the signal of telecommunication received.
2. the communication means that the described visible light communication system of claim 1 adopts, is characterized in that comprising the steps:
(1) the input data are carried out to the DFT-S-OFDM modulation, and generate the signal of telecommunication;
(2) signal of telecommunication step (1) generated is converted to light signal and sends;
(3) light signal that receiving step (2) sends is changed to the signal of telecommunication;
(4) signal of telecommunication step (43) generated carries out the DFT-S-OFDM demodulation, thus the described input data of reduction step (1).
3. a kind of visible light communication method according to claim 2, is characterized in that described step (1) comprises the steps:
(11) the FFT operation of establishing the DFT diffusion is counted as the M point, to input data { x
k, k=0,1 ..., M-1} carries out M point DFT operation, is converted into frequency-region signal { X
l, l=0,1 ..., M-1};
(12) establishing OFDM subcarrier in frequency domain number is N, and the number of LED driver module is L, and N OFDM subcarrier in frequency domain distributed to L LED driver module, the frequency-region signal { X then according to the subcarrier allocation rule, step (11) obtained
l, l=0,1 ..., M-1} is mapped on N OFDM subcarrier in frequency domain, and carries out circumference conjugation symmetry arrangement and process;
(13) to the frequency-region signal { X after step (12) processing
l, l=0,1 ..., M-1} carries out N point IFFT conversion, generates OFDM time-domain signal { y
n, n=0,1 ..., N-1}, export after then before the OFDM time-domain signal, adding Cyclic Prefix;
(14) by the OFDM time-domain signal { y of step (13) output
n, n=0,1 ..., N-1} carries out exporting after digital-to-analogue conversion.
4. a kind of visible light communication method according to claim 3, is characterized in that described step (12) comprises the steps:
(121) establish N OFDM subcarrier in frequency domain { y
k, k=1,2 ..., N}, distribute to L LED driver module by N OFDM subcarrier in frequency domain, at { y
k, k=1, place real number signal on two subcarriers of N/2+1};
(122) by frequency-region signal { X
l, l=0,1 ..., M-1} is mapped to OFDM subcarrier in frequency domain { y
k, k=1,2 ..., in N/2} on the continuous subcarrier of M, all the other N/2-M-1 subcarrier zero paddings;
(123) by OFDM subcarrier in frequency domain { y
k, k=N/2+2, N/2+3 ..., N} fills respectively its subcarrier about N/2+1 subcarrier symmetry { y
k, k=N/2, N/2-1 ..., the conjugate symmetric data of the symbol on 2}.
5. a kind of visible light communication method according to claim 3, is characterized in that described step (12) comprises the steps:
(121) establish N OFDM subcarrier in frequency domain { y
k, k=1,2 ..., N}, distribute to L LED driver module by N OFDM subcarrier in frequency domain, at { y
k, k=1, place real number signal on two subcarriers of N/2+1};
(122) choose at random OFDM subcarrier in frequency domain { y
k, k=2,3 ..., a subcarrier in N/2}, be made as { y
k, k=T}, by frequency-region signal { X
l, l=0} is mapped to subcarrier { y
k, k=T} is upper, by frequency-region signal { X
l, l=1} is mapped to subcarrier { y
k, k=T+N/2M} is upper, by that analogy, every N/2M-1 subcarrier mapping once, until complete frequency-region signal { X
l, l=0,1 ..., M-1} is to OFDM subcarrier in frequency domain { y
k, k=2,3 ..., the mapping of N/2};
(123) by OFDM subcarrier in frequency domain { y
k, k=N/2+2, N/2+3 ..., N} fills respectively its subcarrier about N/2+1 subcarrier symmetry { y
k, k=N/2, N/2-1 ..., the conjugate symmetric data of the symbol on 2}.
6. a kind of visible light communication method according to claim 3 characterized by further comprising: OFDM subcarrier in frequency domain N=S*L in described step (12), and S is positive integer, N OFDM subcarrier in frequency domain is averagely allocated to L LED driver module.
7. a kind of visible light communication method according to claim 3, is characterized in that described step (4) comprises the steps:
(41) signal of telecommunication step (3) sent carries out analog-to-digital conversion, obtains the front digital signal of demodulation;
(42) Cyclic Prefix in the digital signal that removal step (41) obtains, and carry out N point FFT conversion, obtain N OFDM frequency domain carrier signal;
(43) N OFDM frequency domain carrier signal step (42) obtained carried out channel estimating, and carries out the OFDM frequency domain equalization according to the channel tap coefficient of estimating;
(44) the subcarrier allocation rule that corresponding step (12) adopts, the carrier signal that step (7) is obtained is done reverse operating, takes out M effectively sub-carrier signal { X
l, l=0,1 ..., M-1}, and carry out M point IDFT operation, the final described input data of reduction step (1) { x
k, k=0,1 ..., M-1}.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310407821.2A CN103457661B (en) | 2013-09-09 | 2013-09-09 | A kind of LED array visible light communication system and communication means thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310407821.2A CN103457661B (en) | 2013-09-09 | 2013-09-09 | A kind of LED array visible light communication system and communication means thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103457661A true CN103457661A (en) | 2013-12-18 |
| CN103457661B CN103457661B (en) | 2016-08-17 |
Family
ID=49739677
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310407821.2A Active CN103457661B (en) | 2013-09-09 | 2013-09-09 | A kind of LED array visible light communication system and communication means thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN103457661B (en) |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103684598A (en) * | 2014-01-06 | 2014-03-26 | 中国人民解放军信息工程大学 | Visible light communication system |
| CN103716094A (en) * | 2014-01-06 | 2014-04-09 | 中国人民解放军信息工程大学 | Visible light communication front end circuit |
| CN104796195A (en) * | 2015-03-25 | 2015-07-22 | 东南大学 | Visible light multi-carrier transmission method using multiplicative clipping |
| CN105119655A (en) * | 2015-08-31 | 2015-12-02 | 华南理工大学 | Visible light communication method based on QAM and MPPM and system thereof |
| CN106330308A (en) * | 2015-07-09 | 2017-01-11 | 深圳市裕富照明有限公司 | LED visible light communication equipment and automatic switching method thereof |
| CN106850056A (en) * | 2017-03-28 | 2017-06-13 | 东南大学 | A kind of method of assessment PAM OFDM visible light communication system signal peak-to-average ratios |
| CN107276671A (en) * | 2017-06-21 | 2017-10-20 | 中国科学技术大学 | A kind of method for the indoor visible light communication system for optimizing spatial modulation |
| CN107306240A (en) * | 2016-04-25 | 2017-10-31 | 临沂大学 | One kind is used for visible ray ADCO-OFDM communication system signal detection methods |
| CN109150306A (en) * | 2017-06-16 | 2019-01-04 | 深圳清华大学研究院 | Visible light communication system and method |
| WO2019165618A1 (en) * | 2018-02-27 | 2019-09-06 | 西南交通大学 | Distributed device for monitoring electromagnetic interference along high-speed rail in real time and related method |
| CN110324266A (en) * | 2019-05-16 | 2019-10-11 | 华南师范大学 | A kind of visible optical transceiving method of OFDM of Adaptive Transmission amplitude digit compression |
| CN111682901A (en) * | 2020-06-16 | 2020-09-18 | 四川大学 | Information transmission method, information sending device, information receiving device and system |
| CN111934766A (en) * | 2020-06-15 | 2020-11-13 | 中山大学 | Visible light communication system |
| CN112468231A (en) * | 2020-11-19 | 2021-03-09 | 长江大学 | LED polarization array visible light transmission system |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106357332B (en) * | 2016-10-20 | 2018-08-17 | 东南大学 | A kind of multiple-input and multiple-output visible light communication system |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102224692A (en) * | 2008-11-25 | 2011-10-19 | 三星电子株式会社 | Visible ray communication system and method for transmitting signal |
| CN102244635A (en) * | 2011-07-07 | 2011-11-16 | 清华大学 | Visible light communication system and method thereof |
| US20120224655A1 (en) * | 2011-03-04 | 2012-09-06 | Electronics And Telecommunications Research Institute | Apparatus and method for transmitting and receiving data |
| CN102684819A (en) * | 2011-03-15 | 2012-09-19 | 华为技术有限公司 | Data transmission method, relative device and relative system |
-
2013
- 2013-09-09 CN CN201310407821.2A patent/CN103457661B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102224692A (en) * | 2008-11-25 | 2011-10-19 | 三星电子株式会社 | Visible ray communication system and method for transmitting signal |
| US20120224655A1 (en) * | 2011-03-04 | 2012-09-06 | Electronics And Telecommunications Research Institute | Apparatus and method for transmitting and receiving data |
| CN102684819A (en) * | 2011-03-15 | 2012-09-19 | 华为技术有限公司 | Data transmission method, relative device and relative system |
| CN102244635A (en) * | 2011-07-07 | 2011-11-16 | 清华大学 | Visible light communication system and method thereof |
Cited By (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103684598A (en) * | 2014-01-06 | 2014-03-26 | 中国人民解放军信息工程大学 | Visible light communication system |
| CN103716094A (en) * | 2014-01-06 | 2014-04-09 | 中国人民解放军信息工程大学 | Visible light communication front end circuit |
| CN103716094B (en) * | 2014-01-06 | 2016-06-01 | 中国人民解放军信息工程大学 | A kind of visible light communication front end circuit |
| CN103684598B (en) * | 2014-01-06 | 2017-05-10 | 中国人民解放军信息工程大学 | Visible light communication system |
| CN104796195A (en) * | 2015-03-25 | 2015-07-22 | 东南大学 | Visible light multi-carrier transmission method using multiplicative clipping |
| CN104796195B (en) * | 2015-03-25 | 2017-05-10 | 东南大学 | Visible light multi-carrier transmission method using multiplicative clipping |
| CN106330308A (en) * | 2015-07-09 | 2017-01-11 | 深圳市裕富照明有限公司 | LED visible light communication equipment and automatic switching method thereof |
| CN105119655A (en) * | 2015-08-31 | 2015-12-02 | 华南理工大学 | Visible light communication method based on QAM and MPPM and system thereof |
| CN107306240A (en) * | 2016-04-25 | 2017-10-31 | 临沂大学 | One kind is used for visible ray ADCO-OFDM communication system signal detection methods |
| CN107306240B (en) * | 2016-04-25 | 2021-05-25 | 临沂大学 | Signal detection method for visible light ADCO-OFDM communication system |
| CN106850056A (en) * | 2017-03-28 | 2017-06-13 | 东南大学 | A kind of method of assessment PAM OFDM visible light communication system signal peak-to-average ratios |
| CN109150306B (en) * | 2017-06-16 | 2020-06-30 | 深圳清华大学研究院 | Visible light communication system and method |
| CN109150306A (en) * | 2017-06-16 | 2019-01-04 | 深圳清华大学研究院 | Visible light communication system and method |
| CN107276671A (en) * | 2017-06-21 | 2017-10-20 | 中国科学技术大学 | A kind of method for the indoor visible light communication system for optimizing spatial modulation |
| CN107276671B (en) * | 2017-06-21 | 2020-03-31 | 中国科学技术大学 | Method for optimizing indoor visible light communication system of spatial modulation |
| WO2019165618A1 (en) * | 2018-02-27 | 2019-09-06 | 西南交通大学 | Distributed device for monitoring electromagnetic interference along high-speed rail in real time and related method |
| CN110324266A (en) * | 2019-05-16 | 2019-10-11 | 华南师范大学 | A kind of visible optical transceiving method of OFDM of Adaptive Transmission amplitude digit compression |
| CN110324266B (en) * | 2019-05-16 | 2022-03-11 | 华南师范大学 | OFDM visible light receiving and transmitting method and system for self-adaptive transmission amplitude and digit compression |
| CN111934766A (en) * | 2020-06-15 | 2020-11-13 | 中山大学 | Visible light communication system |
| CN111682901A (en) * | 2020-06-16 | 2020-09-18 | 四川大学 | Information transmission method, information sending device, information receiving device and system |
| CN111682901B (en) * | 2020-06-16 | 2023-11-21 | 四川大学 | Information transmission method, information sending device, information receiving device and system |
| CN112468231A (en) * | 2020-11-19 | 2021-03-09 | 长江大学 | LED polarization array visible light transmission system |
Also Published As
| Publication number | Publication date |
|---|---|
| CN103457661B (en) | 2016-08-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103457661B (en) | A kind of LED array visible light communication system and communication means thereof | |
| CN101356755B (en) | Method and apparatus for pilot signal transmission | |
| CN102724032B (en) | Method and apparatus for transmitting and receiving information of an uncoded channel in an orthogonal frequency division multiplexing system | |
| CN102638437B (en) | Multi-carrier transmission method and device based on selected carrier modulation | |
| CN104780033B (en) | A kind of self-adaptive method for allotting sub carriers for SIM ofdm systems | |
| WO2009070983A1 (en) | Method, system and apparatus for signal generation and message transmission in broadband wireless communications | |
| CN105049398B (en) | A kind of adjustable modulator approach of constellation point mapping mode based on the modulation of carrier wave label | |
| CN108900291A (en) | Data-pilot frequency design joint index modulator approach for SIM-OFDM system | |
| CN105493427A (en) | Method and apparatus for generating a phy header field | |
| CN108847917B (en) | Orthogonal frequency division multiplexing transmission method modulated by pilot frequency pattern | |
| CN102638436B (en) | Method and system for realizing high-security fast frequency-hopping transmission | |
| CN108259403A (en) | A kind of VLC/RF mixes OFDM baseband system | |
| US20100329196A1 (en) | Method and apparatus for transmitting uplink control channel in a mobile communication system | |
| CN110808822A (en) | Digital random multi-frequency-point frequency hopping time hopping information transmission method and system | |
| CN106230766A (en) | The comprehensive adaptive transmission method of visible light communication | |
| CN103647740A (en) | Multi-carrier modulation and demodulation method of orthogonal non-uniform multi-carrier spacing based on Ramanujan summation | |
| CN101371453A (en) | Wireless communications system employing OFDMA and CDMA techniques | |
| CN1968237B (en) | Apparatus and method for reducing mean peak power rate in orthogonal frequency-division multiplexing system | |
| CN213461748U (en) | Broadband power line carrier communication system based on OFDM technology | |
| Saied et al. | Single carrier optical FDM in visible light communication | |
| CN107949060A (en) | A kind of power distribution method for mixing circulation prefix orthogonal frequency division multiple access | |
| CN108365875A (en) | The method and mimo system of multiple antennas PAPR are reduced based on precoding | |
| CN112543041A (en) | Broadband power line carrier communication system and method based on OFDM technology | |
| Vora et al. | Index Modulation with PAPR and Beamforming for 5G MIMO-OFDM | |
| CN109039967B (en) | Solution method of f-OFDM system ISI based on ICI self-deletion technology |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |