CN106953824A - A kind of OFDM symbol synchronous modulation method cooperateed with based on time domain and frequency domain - Google Patents
A kind of OFDM symbol synchronous modulation method cooperateed with based on time domain and frequency domain Download PDFInfo
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- CN106953824A CN106953824A CN201710139909.9A CN201710139909A CN106953824A CN 106953824 A CN106953824 A CN 106953824A CN 201710139909 A CN201710139909 A CN 201710139909A CN 106953824 A CN106953824 A CN 106953824A
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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
- H04L27/2602—Signal structure
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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
-
- 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
- H04L27/2668—Details of algorithms
- H04L27/2669—Details of algorithms characterised by the domain of operation
-
- 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
- H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
- H04L27/2692—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation with preamble design, i.e. with negotiation of the synchronisation sequence with transmitter or sequence linked to the algorithm used at the receiver
Abstract
The invention discloses a kind of OFDM symbol synchronous modulation method cooperateed with based on time domain and frequency domain, first, storage leading symbol carries out slightly synchronously estimating, and carry out thick synchronous modulation using time domain correlation module into frequency domain constellation table to symbol；Then, under the cooperation of frequency domain constellation table, the smart synchronous adjustment of symbol is carried out to frequency-region signal using frequency domain correlation module and is calculated, and carries out smart synchronous modulation；Finally, after time-frequency convert and frequency-region signal demodulation, OFDM symbol synchronous modulation process is completed.Its sign synchronization modulation accuracy is high, and process is simple, and computational complexity is substantially reduced, and synchronization dependability is high, and performance is stable, is adapted to the use of various communications protocol and various header type symbols.
Description
Technical field
The present invention relates to a kind of OFDM modulation method, it is more particularly to a kind of for sign synchronization, based on time domain and frequency domain
The OFDM modulation method of collaboration, belongs to communication technique field.
Background technology
Existing broadband connections mainly uses OFDM modulation systems, and it has the availability of frequency spectrum high, and the weak ability of anti-multipath is strong
The advantages of.In the wireless and cable broadband communications field, such as：DVB-T, WiFi, ITU-T G.hn, HomePlug AV and country
Power network broadband PLC agreements etc. are widely used.Wherein, sign synchronization receives one of core algorithm of demodulation as OFDM, directly
Influence demodulation performance and demodulation quality.To avoid intersymbol interference, receiver needs precise synchronization OFDM symbol, and referred to as symbol is determined
When, to reach good receptivity.
Traditional OFDM symbol is synchronous all to be completed using time domain related algorithm, and it is broadly divided into two classes：
1st, auto-correlation sign synchronization is slided（Sliding Auto-Correlation）
Wherein：N is the symbol sampler cycle, and x is time-domain sampling value, and y is slip correlation.
A y peak value, as sign synchronization border are found in symbol period.
The algorithm operation quantity is small, and each sampled point correlation y (n+1) only needs to be based on previous sampled point correlation y (n)
Do multiplication twice, it is necessary to resource it is less.But obtained relevant peaks are not a precipitous pulses, but a triangular peak,
It is larger by interference effects such as noises, it is impossible to obtain accurate timing position.
2nd, the slip cross-correlation sign synchronization based on leading symbol（Sliding Cross Correlation）
Wherein：L is correlation window length, and x is time-domain sampling value, and r is leading symbol reference sample value sequence, and y is slip correlation.
A y peak value, as sign synchronization border are found in symbol period.
The algorithm correlation peak is sharp pulse, comparatively facilitates accurate symbol slightly synchronous.But in multipath channel feelings
Multiple correlation peaks occur under condition, and are influenceed larger by frequency deviation, further, since each sampled point needs to complete whole associated windows
Correlation computations in long L, operand is big, it is necessary to consume more chip logic resource, causes the rising of power consumption and cost.
How to improve this case, improve the reliability of symbol synchronization process, cut operating costs, just think as the present invention
The problem of solving.
The content of the invention
In view of the deficiency that above-mentioned prior art is present, the present invention is intended to provide one kind is drawn on the basis of time domain related algorithm
Enter frequency domain computing, a kind of OFDM symbol synchronous modulation method being combined based on time domain and frequency domain is formed, with Creative Thinking solution
Certainly the contradiction between synchronization accuracy and computational complexity, realizes the purpose of symbol accurate synchronization.
The present invention is achieved through the following technical solutions：
A kind of OFDM symbol synchronous modulation method cooperateed with based on time domain and frequency domain, specific steps are included：
Step 1, according to communications protocol to be modulated configure frequency domain constellation table content, storage leading symbol into frequency domain constellation table.
Step 2, when time-domain signal as input signal enter receiving channel when, in time domain correlation module using slide from
Related symbol synchronized algorithm carries out OFDM symbol and slightly synchronously estimated, obtains thick synchronous adjustment amount.
Step 3, thick synchronous modulation carried out to time-domain signal in synchronous coarse adjustment according to thick synchronous adjustment amount.
Step 4, fast Fourier transform module carry out time-frequency convert to the time-domain signal after thick synchronous modulation, and frequency domain is related
The frequency domain constellation table that module is stored according to the frequency-region signal and early stage received carries out the smart synchronous adjustment of frequency domain related symbol and calculated,
Obtain smart synchronous adjustment amount.
Step 5, the time-domain signal after coarse adjustment is fed back in synchronous accurate adjustment according to smart synchronous adjustment amount after essence it is same
Step system.
Step 6, fast Fourier transform module carry out time domain to the time-domain signal after smart synchronous modulation to the conversion of frequency domain.
Step 7, through frequency-domain demodulation module carry out frequency-region signal demodulation after, complete OFDM symbol synchronous modulation process.
In the step 4, frequency domain correlation module completes smart synchronous adjustment amount according to following equation and calculated：
Wherein,For the reception data frequency-region signal after fast Fourier transform module is changed；To be preceding
The frequency domain constellation table signal of symbol reference is led, k is subcarrier in frequency domain sequence number, is calculatedValue, the as essence using point are same
Successive step amount.
A kind of beneficial effect bag of OFDM symbol synchronous modulation method cooperateed with based on time domain and frequency domain of the present invention
Include：
1st, the related algorithm cooperateed with using time domain and with frequency domain synchronizes modulation to OFDM symbol, and synchronization dependability is high, performance
It is stable；
2nd, leading symbol reference value as frequency domain correlation module in frequency domain constellation table is stored in advance, and pass through flexible configuration
Mode to adapt to the use of various agreements and various header types, facilitate frequency domain correlation computations process；
3rd, due to each sign computation of frequency domain related algorithm once, amount of calculation is reduced, beneficial to the resource optimization of integrated circuit；
4th, sign synchronization modulation accuracy is high, and process is simple, and computational complexity is substantially reduced.
Brief description of the drawings
Fig. 1 is structural schematic block diagram of the invention.
Embodiment
1 the present invention will be further described below in conjunction with the accompanying drawings, and thick lines are signal stream in figure, and hachure is control
Stream.
A kind of OFDM symbol synchronous modulation method cooperateed with based on time domain and frequency domain of the present invention, specific steps bag
Include：
Step 1, according to communications protocol to be modulated configure frequency domain constellation table content, storage leading symbol into frequency domain constellation table.
Leading symbol is prestored in frequency domain constellation table, frequency domain related algorithm is supplied to as reference synchronization, to ensure
The accuracy of leading symbol and flexibility is used, and according to agreement flexible configuration leading symbol, different agreement is adapted to reaching
Purpose.
Step 2, when time-domain signal as input signal enter receiving channel when, in time domain correlation module using slide from
Related symbol synchronized algorithm carries out OFDM symbol and slightly synchronously estimated, obtains thick synchronous adjustment amount.
Step 3, thick synchronous modulation carried out to time-domain signal in synchronous coarse adjustment according to thick synchronous adjustment amount.
Step 4, fast Fourier transform module carry out time-frequency convert to the time-domain signal after thick synchronous modulation, and frequency domain is related
The frequency domain constellation table that module is stored according to the frequency-region signal and early stage received carries out the smart synchronous adjustment of frequency domain related symbol and calculated,
Obtain smart synchronous adjustment amount.
Wherein, frequency domain correlation module completes smart synchronous adjustment amount calculating according to following equation：
For the reception data frequency-region signal after fast Fourier transform module is changed；For leading symbol
The frequency domain constellation table signal of reference；K is subcarrier in frequency domain sequence number.CalculateValue, as using the smart synchronous adjustment of point
Amount.
Step 5, smart synchronous modulation carried out to the time-domain signal after coarse adjustment in synchronous accurate adjustment according to smart synchronous adjustment amount.
Step 6, the conversion using fast Fourier transform module to the time-domain signal progress time domain after accurate adjustment to frequency domain.
Step 7, through frequency-domain demodulation module carry out frequency-region signal demodulation after, complete OFDM symbol synchronous modulation, be entirely based on
Time domain and the OFDM symbol synchronous modulation process of frequency domain collaboration are completed.
Claims (2)
1. a kind of OFDM symbol synchronous modulation method cooperateed with based on time domain and frequency domain, it is characterised in that specific steps include：
Step 1, according to communications protocol to be modulated configure frequency domain constellation table content, storage leading symbol into frequency domain constellation table；
Step 2, when time-domain signal as input signal enter receiving channel when, in time domain correlation module using slide auto-correlation
Sign synchronization algorithm carries out OFDM symbol and slightly synchronously estimated, obtains thick synchronous adjustment amount；
Step 3, thick synchronous modulation carried out to time-domain signal in synchronous coarse adjustment according to thick synchronous adjustment amount；
Step 4, fast Fourier transform module carry out time-frequency convert, frequency domain correlation module to the time-domain signal after thick synchronous modulation
The frequency domain constellation table stored according to the frequency-region signal and early stage received carries out the smart synchronous adjustment of frequency domain related symbol and calculated, and obtains
Smart synchronous adjustment amount；
Step 5, the time-domain signal after coarse adjustment is fed back in synchronous accurate adjustment according to smart synchronous adjustment amount after smart same step
System；
Step 6, fast Fourier transform module carry out time domain to the time-domain signal after smart synchronous modulation to the conversion of frequency domain；
Step 7, through frequency-domain demodulation module carry out frequency-region signal demodulation after, complete OFDM symbol synchronous modulation process.
2. a kind of OFDM symbol synchronous modulation method cooperateed with based on time domain and frequency domain according to claim 1, its feature
It is that in the step 4, frequency domain correlation module completes smart synchronous adjustment amount according to following equation and calculated：
Wherein,For the reception data frequency-region signal after fast Fourier transform module is changed；To be preceding
The frequency domain constellation table signal of symbol reference is led, k is subcarrier in frequency domain sequence number；
CalculateValue, as using the smart synchronous adjustment amount of point.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111277533A (en) * | 2020-02-12 | 2020-06-12 | 电子科技大学 | Constellation diagram-based OFDM signal symbol timing position estimation method |
| CN111277535A (en) * | 2020-03-16 | 2020-06-12 | 成都希德电子信息技术有限公司 | Frequency-division time-division high-precision OFDM synchronization method and system |
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| CN101442520A (en) * | 2007-11-20 | 2009-05-27 | 中兴通讯股份有限公司 | Timing synchronization method for radio communication system uplink |
| CN101764780A (en) * | 2009-12-28 | 2010-06-30 | 北京中星微电子有限公司 | Method and system for time and frequency synchronization in orthogonal frequency division multiplexing |
| CN101815048A (en) * | 2009-02-19 | 2010-08-25 | 中国科学院微电子研究所 | Frequency domain joint estimation method of OFDM (Orthogonal Frequency Division Multiplexing) integer frequency offset and fine symbol synchronization |
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2017
- 2017-03-10 CN CN201710139909.9A patent/CN106953824A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101442520A (en) * | 2007-11-20 | 2009-05-27 | 中兴通讯股份有限公司 | Timing synchronization method for radio communication system uplink |
| CN101815048A (en) * | 2009-02-19 | 2010-08-25 | 中国科学院微电子研究所 | Frequency domain joint estimation method of OFDM (Orthogonal Frequency Division Multiplexing) integer frequency offset and fine symbol synchronization |
| CN101764780A (en) * | 2009-12-28 | 2010-06-30 | 北京中星微电子有限公司 | Method and system for time and frequency synchronization in orthogonal frequency division multiplexing |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111277533A (en) * | 2020-02-12 | 2020-06-12 | 电子科技大学 | Constellation diagram-based OFDM signal symbol timing position estimation method |
| CN111277533B (en) * | 2020-02-12 | 2021-07-02 | 电子科技大学 | Constellation diagram-based OFDM signal symbol timing position estimation method |
| CN111277535A (en) * | 2020-03-16 | 2020-06-12 | 成都希德电子信息技术有限公司 | Frequency-division time-division high-precision OFDM synchronization method and system |
| CN111277535B (en) * | 2020-03-16 | 2022-10-25 | 成都希德电子信息技术有限公司 | Frequency-division time-division high-precision OFDM synchronization method and system |
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