CN107426130A - The symbol timing synchronization method of visible light communication - Google Patents
The symbol timing synchronization method of visible light communication Download PDFInfo
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- CN107426130A CN107426130A CN201710606058.4A CN201710606058A CN107426130A CN 107426130 A CN107426130 A CN 107426130A CN 201710606058 A CN201710606058 A CN 201710606058A CN 107426130 A CN107426130 A CN 107426130A
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- dynamic threshold
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2662—Symbol synchronisation
- H04L27/2665—Fine synchronisation, e.g. by positioning the FFT window
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
- H04B10/114—Indoor or close-range type systems
- H04B10/116—Visible light communication
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/30—Monitoring; Testing of propagation channels
- H04B17/391—Modelling the propagation channel
- H04B17/3912—Simulation models, e.g. distribution of spectral power density or received signal strength indicator [RSSI] for a given geographic region
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Abstract
The invention discloses the symbol timing synchronization method of visible light communication, mainly solve more spikes existing for prior art, timing synchronization position is swung and it is determined that the problems such as the wasting of resources caused by the correct timing position used time is long.Implementation step is：1st, the foundation of channel model；2nd, mobile correlation Z size is calculated；3rd, the size of dynamic threshold is calculated；4th, the size of relatively more mobile correlation and dynamic threshold, if detecting certain moment, when mobile correlation is more than or equal to dynamic threshold, then position now is exactly the timing position of symbol.The present invention symbol timing synchronization method, it is possible to achieve symbol be accurately positioned and it is real-time, especially under conditions of low signal-to-noise ratio, possess the advantage that prior art can not be shoulder to shoulder.The present invention has a good application prospect in visible light communication.
Description
Technical field
The present invention relates to communication technology application field, more particularly to time synchronization method, available for visible light communication system
It is middle to carry out real-time timing synchronization.
Background technology
Along with the Fast Growth of mobile Internet industry, WiFi has become the necessity in people's life.But
The problems such as WiFi application fields are limited, spectral range is narrow also being exposed increasingly.In view of this, it is seen that optical communication technique quilt
It is proposed, it has communication and illumination dual-use function concurrently, becomes a focus of communications field research in recent years.OFDM is communication neck
A kind of modulation system that domain is most widely used, its bandwidth is divided into many mutually orthogonal subcarriers, so its spectrum utilization
Rate is very high, and CP (cyclic prefix) addition efficiently solves ISI (intersymbol interference) and ICI (being disturbed between subchannel).So
And the precondition of above-mentioned advantage is that to have good orthogonality between subcarrier, influence of the frequency shift (FS) to orthogonality is especially big,
Want the skew of correction frequency, it is necessary to which the net synchronization capability of this system is good.At present, simultaneous techniques exist " relevant peaks platform " and
More spikes and it is determined that the problems such as the wasting of resources caused by the correct timing position used time is long, for this problem, the present invention
Disclose a kind of symbol timing synchronization method of visible light communication.
At present, the signal-timing method that the present invention refers to is broadly divided into two classes：Auxiliary type symbol based on training sequence is determined
Shi Fangfa and the additional type signal-timing method based on non-training sequence.The former utilizes the distinctive correlation of training sequence and knot
Structure feature obtains timing slip, can be with although the method is lower than non-training sequence method in terms of frequency efficiency
Obtain more accurate Symbol Timing result, and and its severe channel condition under still can obtain good performance.
Classical signal-timing method based on training sequence includes S＆C algorithms, Minn algorithms and Park algorithms, above-mentioned three kinds classical calculations
Method using training sequence design feature and timing slip estimation function is obtained by related operation, when timing slip estimation function
It is just correct Symbol Timing position during acquirement maximum.But three kinds of described classic algorithms reality application in there is
Clearly the problem of, mainly including following two aspects：
One is spike problem：S＆C algorithms occur one section of " flat region " in correct FFT windows vicinity, are formed
So-called " relevant peaks platform "；There is spike phenomenon in Minn algorithms, solve the plateau phenomenon in S＆C algorithms, so as to one
Determine to improve timing accuracy in degree, but the problems such as some submaximums and not sharp enough spike be present；Although Park algorithms go out
Sharp main peak is showed but has had that sharp submaximum occurs and computation complexity is higher.
The second is real-time and problem of resource waste:Above-mentioned three kinds of classic algorithms are all to obtain timing estimation function
Be determined starting point during maximum, namely accurate timing position, however want to obtain maximum that we want just will be
Can not determine to be it on earth when continuously being compared in one symbol, therefore obtaining a timing estimation functional value at once
Maximum, thus want determine timing function estimate be maximum we at least need to judge that a symbol period can
Judge, the method just extends the processing delay of Symbol Timing process, it is impossible to it is same to carry out completion Symbol Timing in real time
Step problem.
The content of the invention
It is a primary object of the present invention to provide a kind of symbol timing synchronization method of visible light communication.Can effectively it solve
Certainly sharp and single timing estimation function maxima is not present in prior art, and it is determined that correct timing position used time mistake
Problem of resource waste caused by length.
Timing synchronization technical scheme implementation process disclosed by the invention is as follows：
(1) foundation of channel model is carried out, channel model is the vital part of visible light communication system, channel
Impulse response expression formula can be expressed as：System receiving terminal data sequence we represent
For：
(2) calculate mobile correlation Z size, Z numerical values recited we can be expressed as：
(3) size of dynamic threshold is calculated, first has to calculate the energy in receiving data sequence correlation length, Zhi Houzai
It is multiplied by a constant coefficient (having engineering experience to determine this constant) thus size of the value as threshold value.
(4) size of relatively mobile correlation and dynamic threshold, if detecting certain moment, mobile correlation be more than or
When person is equal to dynamic threshold, then position now is exactly the timing position of symbol.
(5) FPGA of sign synchronization is realized, overall sync section uses two EP2C35 and Quartus II softwares
Emulation experiment is carried out, FFT module as line of demarcation, the part before FFT is timing synchronization and coarse frequency synchronization, FFT
Part below is that frequency fine synchronization and sampling clock are synchronous.
Compared with prior art, the symbol timing synchronization method of visible light communication provided by the invention, have in low noise
Than when timing position it is stable and accurate, function admirable and real-time are stronger, are easy to Project Realization, economize on resources,
There to be good application prospect in visible light communication.
Brief description of the drawings
Accompanying drawing described herein is used for providing a further understanding of the present invention, forms the part of the present invention, this hair
Bright schematic description and description is used to explain the present invention, does not form inappropriate limitation of the present invention.In the accompanying drawings：
The entirety that Fig. 1 is the present invention realizes block diagram；
Fig. 2 is that sync section FPGA realizes schematic diagram；
Fig. 3 is change schematic diagram of the timing estimation mean square deviation under Gaussian channel with signal to noise ratio；
Fig. 4 is change schematic diagram of the timing estimation mean square deviation under more channels with signal to noise ratio.
Embodiment
To make the object, technical solutions and advantages of the present invention clearer, below in conjunction with drawings and the specific embodiments, to this
Invention is described in further detail.
Shown in reference picture 1, specific implementation step of the invention is as follows：
1st, the foundation of channel model
In the transmitting terminal of ofdm system, the sampled I FFT expression formula of n-th of OFDM symbol is：N=0,1 ..., N-1, N ＞ 2NuWhat+1, N were represented is total carrier number in each OFDM symbol,
It is modulated to k-th of subcarrier data above symbol XkTo represent, 2Nu+ 1 represents the number of actual transmissions subcarrier, plus CP
The data sent afterwards are：The impulse response expression formula of channel can
To be expressed as:τiRepresent the signal delay on road, τiRepresent the decay factor of the i-th tunnel signal amplitude.
The sequence of the reception end data of ofdm system we be expressed as：
HkK-th of subcarrier of channel transfer function is represented, T represents the total time of a symbol, TuIt is the time of significant character, TsTable
Show the nominal of sampling timing, w (nTs) it is that variance isAverage is the process of 0 multiple white Gaussian noise, and ξ represents determining for symbol
Hour offset, ε represent the skew of carrier frequency, θ0Represent the error of common phase.
2nd, mobile correlation Z size is calculated
Make pqQ-th continuously insertion pilot tone, q=1 therein, 2 ..., Q are represented, enters the IFFT of N rows point for convenience
Conversion, just inserts at some 0 point in non-pilot position：Y=0 ..., 0, p1,0,...,0,pq, 0 ..., 0 }, Z numerical values recited
We can be expressed as：ynAs illustrated in step 1,For the oeprator of convolution.
3rd, the size of dynamic threshold is calculated
First have to calculate the energy in receiving data sequence correlation length, (have engineering multiplied by a constant coefficient afterwards
Experience determines this constant) thus size of the value as threshold value.
4th, the size of relatively more mobile correlation and dynamic threshold
If detecting certain moment, when mobile correlation is more than or equal to dynamic threshold, then position now is exactly
The timing position of symbol.
5th, the FPGA of sign synchronization is realized
Implementation process is as shown in Fig. 2 overall sync section is carried out using two EP2C35 and Quartus II softwares
Emulation experiment, FFT module as line of demarcation, the part before FFT is timing synchronization and coarse frequency synchronization, behind FFT
Part be that frequency fine synchronization and sampling clock are synchronous.In order to simplify the structure of realization, we can lead known to a use
Frequency signal code position, high several after data-signal taken amount are received as correlation estimation computing, still can so be obtained
Preferable estimation effect.
The present invention effect we can be described further by following emulation：
(1) simulated conditions are as shown in the table：
(2) emulation content and interpretation of result：
As shown in figure 3, it is the emulation changed under Gaussian channel environment to timing estimation mean square deviation with signal to noise ratio, in AWGN
In channel, the mean square error of algorithm of the invention and Park algorithms all close to 0, Minn algorithms mean square error relatively
In 0, due to the reason of platform effect, the mean square error of S＆C algorithms is bigger 70 or so；As shown in figure 4, it is in more channels
The emulation changed under environment to timing estimation mean square deviation with signal to noise ratio, in more channels, the timing of Park and Minn algorithms is same
Step performance is influenceed by channel, and its mean square error has more larger growth, what the innovatory algorithm that the present invention provides was subject to
Influence smaller.Either still all it is significantly less than three kinds of classics in the mean square error of more channel inventive algorithms in awgn channel
Algorithm is especially when low signal-to-noise ratio.
Claims (5)
1. carrying out the foundation of channel model, channel model is the vital part of visible light communication system, the pulse of channel
Response expression formula can be expressed as：System receiving terminal data sequence we be expressed as：。
2. channel model as claimed in claim 1, calculate mobile correlation Z size, Z numerical values recited we can represent
For：。
3. calculate dynamic threshold size, first have to calculate receiving data sequence correlation length in energy, afterwards multiplied by
One constant coefficient (has engineering experience to determine this constant, 0.7) present invention is set to thus size of the value as threshold value.
4. as described in right 2 and right 3, the size of relatively more mobile correlation and dynamic threshold, if detecting certain moment, move
When dynamic correlation is more than or equal to dynamic threshold, then position now is exactly the timing position of symbol.
5. the FPGA of sign synchronization is realized, overall sync section is imitated using two EP2C35 and Quartus II softwares
True experiment, FFT module as line of demarcation, the part before FFT is timing synchronization and coarse frequency synchronization, behind FFT
Part is that frequency fine synchronization and sampling clock are synchronous.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104125190A (en) * | 2014-08-18 | 2014-10-29 | 西安电子科技大学 | OFDM (orthogonal frequency division multiplexing) system symbol timing synchronization realizing method suitable for low-signal-to-noise-ratio channel environments |
| US20150304030A1 (en) * | 2014-04-18 | 2015-10-22 | National Chiao Tung University | Visible light communication method |
| CN106713202A (en) * | 2015-11-18 | 2017-05-24 | 中南大学 | VLC (Visible Light Communication) synchronization algorithm based on zero-autocorrelation code pair |
| CN106921605A (en) * | 2017-01-13 | 2017-07-04 | 北京遥测技术研究所 | A kind of ARTM CPM demodulation of low implementation complexity and synchronous method |
-
2017
- 2017-07-24 CN CN201710606058.4A patent/CN107426130A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20150304030A1 (en) * | 2014-04-18 | 2015-10-22 | National Chiao Tung University | Visible light communication method |
| CN104125190A (en) * | 2014-08-18 | 2014-10-29 | 西安电子科技大学 | OFDM (orthogonal frequency division multiplexing) system symbol timing synchronization realizing method suitable for low-signal-to-noise-ratio channel environments |
| CN106713202A (en) * | 2015-11-18 | 2017-05-24 | 中南大学 | VLC (Visible Light Communication) synchronization algorithm based on zero-autocorrelation code pair |
| CN106921605A (en) * | 2017-01-13 | 2017-07-04 | 北京遥测技术研究所 | A kind of ARTM CPM demodulation of low implementation complexity and synchronous method |
Non-Patent Citations (1)
| Title |
|---|
| 刘贞周: "《可见光通信***的定时同步技术研究》", 《中国优秀硕士学位论文全文数据库》 * |
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