CN106713202A - VLC (Visible Light Communication) synchronization algorithm based on zero-autocorrelation code pair - Google Patents
VLC (Visible Light Communication) synchronization algorithm based on zero-autocorrelation code pair Download PDFInfo
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- CN106713202A CN106713202A CN201510792752.0A CN201510792752A CN106713202A CN 106713202 A CN106713202 A CN 106713202A CN 201510792752 A CN201510792752 A CN 201510792752A CN 106713202 A CN106713202 A CN 106713202A
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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
- H04L27/2657—Carrier synchronisation
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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
- H04L27/2614—Peak power aspects
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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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/50—Reducing energy consumption in communication networks in wire-line communication networks, e.g. low power modes or reduced link rate
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- Computer Networks & Wireless Communication (AREA)
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- Synchronisation In Digital Transmission Systems (AREA)
Abstract
The invention provides a timing synchronization and frequency offset estimation algorithm of a VLC system based on a zero-autocorrelation code pair, and relates to the technical field of VLC. The algorithm comprises the following steps that S1) a set parameter is mapped into the zero-autocorrelation code pair in the data transmitting end, the zero-autocorrelation code pair is combined to form synchronizing symbols according to a set structure, a cross cutting algorithm or u-law companding is selected, the peak-average power ratio of the synchronizing symbols is reduced, and an emitter emits compressed synchronizing symbol data; S2) received original data is calculated in a novel timing measuring method, and is compared with a dynamic threshold to obtain a timing moment and calculate a decimal frequency offset value; and S3) decimal frequency offset compensation is carried out on the received data, and the compensated data is calculated in an integer frequency offset estimation algorithm to obtain an integer frequency offset value. Compared with a zero-autocorrelation code based synchronizing algorithm, the algorithm of the invention is higher in the timing success rate and lower in low frequency offset estimation error, the peak-average power ratio of the synchronizing symbols is lower, and the algorithm is suitable for occasion with high requirement for the peak-average power ratio.
Description
Technical field
The present invention relates to technical field of visible light communication, general zero auto-correlation code pair and new based on this is related generally to
Synchronous and offset estimation scheme.
Background technology
Visible light communication（visible light communication, VLC）It is that a kind of light without using optical fiber leads to
Letter technology, combines the advantage of radio communication and optical communication technique, there is provided wireless, high speed and reliable broadband access.VLC technologies
Electromagnetic radiation is not produced using bandwidth with potentially large number of, is difficult to be influenceed by external electromagnetic interference, it is right to can be widely applied to
Electromagnetic interference sensitivity, the even special occasions without electromagnetic interference.VLC can be tied by the use of its indoor lighting source as base station
Power line communication is closed, easily indoor wireless communication service is provided the user.VLC systems mainly use orthogonal frequency division multiplexi
Modulated signal.
OFDM（Orthogonal frequency division multiplexing, OFDM）It is a kind of wide
The general multi-carrier modulation technology being applied in high rate data transmission communication system.Ofdm system has high spectrum utilization and anti-frequency
The characteristic of rate Selective intensity and be employed in VLC.But ofdm system is very sensitive to Symbol Timing and carrier wave frequency deviation, this two
Individual shortcoming can reduce the performance of system, and can also cause the efficiency of subsequent channel algorithm for estimating reduces.Therefore for VLC-OFDM
For system, research Symbol Timing and Algorithm of Carrier Frequency Offset Estimation are particularly significant.
The content of the invention
Present invention solves the technical problem that being：Improve the timing success rate of VLC-OFDM systems and reduce offset estimation and miss
Difference, improves the communication efficiency of system, improves the performance of communication system.
In order to solve the above-mentioned technical problem, the present invention propose a kind of general zero auto-correlation code to Novel timing it is synchronous with
Offset estimation scheme, comprises the following steps：S1, data sending terminal by setup parameter be mapped to zero auto-correlation code it is right, will obtain
Code to the textural association according to setting into synchronizing symbol, selection pruning algorithm or u rule companding algorithm reduction synchronizing symbols
Peak-to-average power ratio, the synchronizing symbol data after emitter transmitting compression；S2, Novel timing is used to the initial data that obtains of reception
Measure is calculated, and is compared with dynamic threshold, is obtained timing instant and is calculated decimal frequency bias value；S3, to receive data carry out it is small
Data after compensation are calculated by number frequency deviation compensation using integer frequency bias algorithm for estimating, obtain integer frequency bias value.
Above-mentioned technical proposal has the following advantages that：The present invention changes to synchronized algorithm of the tradition based on zero auto-correlation code
Enter, propose that zero auto-correlation code is right, original Timing Processing algorithm is modified, timing point is obtained according to the computational methods for proposing
With offset estimation value.The present invention has the excellent of timing success rate high under low signal-to-noise ratio Rayleigh channel and the inclined evaluated error of low frequency
Point, improves the communication efficiency of system, improves the performance of communication system.
Brief description of the drawings
Fig. 1 be general zero auto-correlation code to mapping graph；
Fig. 2 be general zero auto-correlation code to performance plot；
Fig. 3 is synchronous head structure proposed by the present invention；
Fig. 4 is calculating process block diagram proposed by the present invention；
Fig. 5 is timing metric proposed by the present invention and decimal frequency bias estimation calculation block diagram；
Fig. 6 is integer frequency bias estimation calculation block diagram proposed by the present invention；
Fig. 7 is contrast simulation figure of the conventional method with timing metric of the invention under Gaussian channel；
Fig. 8 is contrast simulation figure of the conventional method with offset estimation error of the invention under Gaussian channel；
Fig. 9 is the contrast simulation figure of timing success rate of the present invention under Rayleigh channel and conventional method；
Figure 10 is the contrast simulation figure of timing error of the present invention under Rayleigh channel and conventional method；
Figure 11 is detailed comparisons' analogous diagram of offset estimation error of the present invention under Rayleigh channel and conventional method.
Specific embodiment
Below in conjunction with the accompanying drawings and example, the present invention is described in further detail.
The present invention propose it is a kind of based on zero auto-correlation code to visible light communication system Timing Synchronization and offset estimation calculate
Method, idiographic flow are as shown in figure 1, including this 3 steps of following S1, S2, S3：
S1, using the mapping relations and the autocorrelation performance of Fig. 2 shown in Fig. 1, produce basic data, the structure according to Fig. 3 is produced
Synchronizing symbol, along with Cyclic Prefix, obtains the synchronizing symbol of ofdm system, after experience peak-to-average power ratio reduction algorithm, transmitting
Machine launches synchronizing symbol data.
Zero auto-correlation code is right：Sequence after QAM mapsCarry out inverse fourier transform and obtain Part I sequence,
According to, to sequenceCarry out inverse fourier transform and obtain Part II sequence, also multiply a factor, this two
Sub-sequenceWithIt is that one group of zero auto-correlation code is right.WhereinDepend onMapping mode, ifIt is that QPSK mappings are produced,
ThenIf,It is that QAM mappings are produced, then, whereinIt is the points of QAM.
S2, as shown in Fig. 4 front portions, synchronizing symbol experience channel, reach receiver, calculate timing metric determine timing
Moment and decimal frequency bias.In detail as shown in figure 5, processing procedure includes：Threshold calculations, measurement results are calculated, multilevel iudge measurement
As a result, timing instant and decimal frequency bias estimate are calculated according to comparative result.Timing metric calculates formula
WhereinIt is IFFT point number,It is to receive data.
Dynamic threshold is represented, whereinRepresent proportionality coefficient.Therefore, correct timing pointFor
WhereinIt is the function for taking the moment, above formula represents the time point of the timing metric of the maximum that takes absolute value.Timing point position
MeasurementAngle be required decimal frequency bias estimate,
Decimal frequency bias estimation range of the invention is。
S3, as shown in Figure 6 to receive data carry out decimal frequency bias compensation, the data after compensation are estimated using integer frequency bias
Algorithm is calculated, and obtains integer frequency bias value.Decimal frequency bias are that integer frequency bias are estimated after estimating, if receiving compensation data decimal frequency bias
Sequence after estimation is.Then integer frequency bias can be calculated by following formula：
WhereinIt is right to representTakeIt is remaining.The estimation range of integer frequency bias isSo total frequency deviationCan be by
It is expressed as
Shown in Fig. 7 under Gaussian channel, the contrast of wang methods, zero auto-correlation code method and timing success rate of the invention.
It can be seen that the present invention and zero auto-correlation code method are essentially all successful, wang algorithms success rate in the case of low signal-to-noise ratio
It is not enough.Therefore in the Gaussian channel of low signal-to-noise ratio, effect of the invention is good enough.
Shown in Fig. 8 under Gaussian channel, wang methods, zero auto-correlation code method and offset estimation error of the invention
Contrast, it can be seen that preferably, wang methods error in the case of low signal-to-noise ratio is too big for effect of the invention, and the present invention is in low letter
Make an uproar well more many than wang method than in the case of, about the 1/3 of the error of wang methods, be the 1/2 of zero auto-correlation code method error,
When signal to noise ratio is improved, three kinds of algorithms have essentially no difference.It can be seen that, the present invention estimates under the Gaussian channel of low signal-to-noise ratio to frequency deviation
The ability of meter is best.
Be displayed under Rayleigh channel in Fig. 9, wang methods, zero auto-correlation code method and timing success rate of the invention it is right
Than.It can be seen that the present invention is essentially all successful, wang methods success rate in the case of low signal-to-noise ratio is not enough.It is several
Planting algorithm is all as the increase success rate of signal to noise ratio is improved, it can be seen that advantage of the present invention in the case of low signal-to-noise ratio is bright
It is aobvious.As can be seen that with the further reduction of signal to noise ratio, success rate of the invention be still it is sufficiently high, and another three kinds of algorithms into
Power will be reduced.
It is displayed under Rayleigh channel in Figure 10, the contrast of wang methods, zero auto-correlation code method and timing error of the invention.
Can wang methods timing error in the case of low signal-to-noise ratio be about at 36 points, the legal time error of zero auto-correlation code is about 8, and this hair
Bright error is about at 4 points, is the 1/9 of wang method errors, the 1/2 of zero auto-correlation code method error.Several algorithms are all with noise
The increase error of ratio reduces, it can be seen that the present invention is with the obvious advantage in the case of low signal-to-noise ratio.
Shown in Figure 11 under Rayleigh channel, wang methods, zero auto-correlation code method and offset estimation error of the invention
Contrast, it can be seen that effect of the invention preferably, zero auto-correlation code method evaluated error be about wang methods error 8/
9, and error of the invention is extremely low, about 1/10 to the 3/10 of wang method errors, therefore the present invention can effectively resist Rayleigh
Decline.
As can be seen from the above embodiments, the present invention can be used for effectively improving Timing Synchronization in VLC-OFDM systems with
Offset estimation performance, particularly in the case of low signal-to-noise ratio Rayleigh fading, hydraulic performance decline will not be a lot, and other two algorithm exists
Fault rate can increase in the case that signal to noise ratio is very low.And data interoperability of the present invention is high, the communication efficiency of system is improved, changed
The performance of kind communication system.
Claims (5)
1. patent of the present invention be related to it is a kind of based on zero auto-correlation code to visible light communication synchronized algorithm, comprise the following steps：
S1, setup parameter is mapped to zero auto-correlation code is right in data sending terminal, the zero auto-correlation that will obtain code is to according to setting
Textural association into synchronizing symbol, use pruning algorithm or u to restrain the peak-to-average power ratio of companding algorithm reduction synchronizing symbol, transmitting
Synchronizing symbol data after machine transmitting compression；
S2, the initial data that obtains of reception is calculated using Novel timing measure, compared with dynamic threshold, when obtaining timing
Carve and calculate decimal frequency bias value；
S3, to receive data carry out decimal frequency bias compensation, the data after compensation are calculated using integer frequency bias algorithm for estimating, obtain
Integer frequency bias value.
2. scheme according to claim 1, it is characterised in that use zero auto-correlation code to the basic number as synchronous head
According to.
3. scheme according to claim 1, it is characterised in that proposed in step S1 zero auto-correlation code to synchronous knot
Structure, and the peak-to-average power ratio of companding algorithm reduction pilot data is restrained using pruning algorithm or u.
4. scheme according to claim 1, it is characterised in that a kind of new timing metric is proposed in step S2 and is calculated
Method, performance is estimated with timing success rate high and excellent decimal frequency bias.
5. scheme according to claim 1, it is characterised in that propose zero auto-correlation code to as synchronous foundation data,
In step sl propose based on zero auto-correlation code to synchronizing symbol structure；This technology is the popularization of zero auto-correlation code；Pass through
S2 and S3 steps obtain timing instant, decimal frequency bias and integer frequency bias, improve the net synchronization capability of system.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201510792752.0A CN106713202A (en) | 2015-11-18 | 2015-11-18 | VLC (Visible Light Communication) synchronization algorithm based on zero-autocorrelation code pair |
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| CN201510792752.0A CN106713202A (en) | 2015-11-18 | 2015-11-18 | VLC (Visible Light Communication) synchronization algorithm based on zero-autocorrelation code pair |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107426130A (en) * | 2017-07-24 | 2017-12-01 | 哈尔滨理工大学 | The symbol timing synchronization method of visible light communication |
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| CN103475618A (en) * | 2013-09-21 | 2013-12-25 | 复旦大学 | Method for synchronizing visible light communication system frames based on OFDM |
| CN103825859A (en) * | 2014-03-10 | 2014-05-28 | 江苏物联网研究发展中心 | Synchronous acquisition method and receiving end equipment of OFDM (orthogonal frequency division multiplexing) signal |
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Application publication date: 20170524 |