CN112910815B - Generalized frequency division multiplexing system time-frequency synchronization method based on positive and negative lead codes - Google Patents

Generalized frequency division multiplexing system time-frequency synchronization method based on positive and negative lead codes Download PDF

Info

Publication number
CN112910815B
CN112910815B CN202110054896.1A CN202110054896A CN112910815B CN 112910815 B CN112910815 B CN 112910815B CN 202110054896 A CN202110054896 A CN 202110054896A CN 112910815 B CN112910815 B CN 112910815B
Authority
CN
China
Prior art keywords
sequence
synchronization
value
frequency
division multiplexing
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.)
Active
Application number
CN202110054896.1A
Other languages
Chinese (zh)
Other versions
CN112910815A (en
Inventor
刘毅
余逸航
万维东
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xidian University
Original Assignee
Xidian University
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Xidian University filed Critical Xidian University
Priority to CN202110054896.1A priority Critical patent/CN112910815B/en
Publication of CN112910815A publication Critical patent/CN112910815A/en
Application granted granted Critical
Publication of CN112910815B publication Critical patent/CN112910815B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0224—Channel estimation using sounding signals
    • 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
    • H04L27/261—Details of reference signals
    • 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
    • H04L27/2626—Arrangements specific to the transmitter only
    • 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
    • H04L27/2663—Coarse synchronisation, e.g. by correlation
    • 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

Abstract

The invention discloses a time-frequency synchronization method of a generalized frequency division multiplexing system based on lead codes with positive and negative polarities, which mainly solves the problems of overlarge calculation complexity and low lead code spectrum efficiency caused by a flat top effect generated during symbol timing synchronization in the prior art. The method comprises the following specific steps: (1) generating a synchronization preamble sequence; (2) adding a Tukey window to the synchronous lead code sequence; (3) sending a modulation sequence loaded with a lead code; (4) coarse symbol timing synchronization; (5) correcting frequency deviation; (6) fine symbol timing synchronization. The invention has lower design complexity, more accurate symbol timing synchronization, higher frequency spectrum efficiency of the synchronous preamble sequence and spectrum resource saving.

Description

Generalized frequency division multiplexing system time-frequency synchronization method based on positive and negative lead codes
Technical Field
The invention belongs to the technical field of communication, and further relates to a time-frequency synchronization method of a generalized frequency division multiplexing system based on lead codes with positive and negative polarities in the technical field of wireless communication modulation. The invention can be used for time-frequency synchronization in a generalized frequency division multiplexing GFDM system and improves the synchronization performance of the system under a fading channel.
Background
The Generalized Frequency Division Multiplexing (GFDM) technology is a novel air interface waveform modulation technology derived on the basis of an OFDM system, and can adaptively adjust a time frequency resource block according to a specific application scene. The basic idea is to modulate data in a time and frequency block structure, each block containing a number of sub-symbols and sub-carriers. The subcarriers are filtered by filters cyclically shifted in time and frequency domains, and finally a cyclic prefix is added outside the data block to improve spectral efficiency. However, at the data receiving end, a receiver is required to be able to perform symbol timing synchronization and carrier frequency offset estimation well. One of the major drawbacks of the synchronization of the current GFDM system is that in order to obtain a better synchronization result, extra calculation is required to eliminate the "flat top effect" caused by the preamble, thereby increasing the complexity of the system.
The patent application document "a generalized frequency division multiplexing time-frequency synchronization method for correcting large frequency offset" (application number: 2018101172643, application publication number: CN108366032A) applied by the university of west ampere electronic technology proposes a generalized frequency division multiplexing time-frequency synchronization method for correcting large frequency offset. The method comprises the following specific steps: designing front and back lead codes with the same parts; secondly, sending an electric signal; thirdly, receiving the electric signal; fourthly, coarse symbol timing synchronization is carried out on the sampling sequence; fourthly, correcting decimal frequency offset; fifthly, estimating the timing moment of the path; and sixthly, correcting the integral multiple frequency offset. The method can well estimate the integral multiple frequency offset. However, the method still has the disadvantage that when the coarse symbol timing synchronization is performed on the sampling sequence, because the preamble design can generate the "flat-top effect", in order to realize the precise synchronization, the influence of the "flat-top effect" can be eliminated by extra calculation, thereby increasing the complexity of the design.
Wuhong et al, in its published paper, "an improved GFDM time-frequency synchronization algorithm" (telecommunication technology, 2016,56(12): 1322-. The method comprises the following implementation steps: firstly, generating a pseudo-random sequence A according to half of the number of subcarriers for transmitting a data block; secondly, generating a pseudorandom sequence B which has the same length as A and is conjugate and symmetrical; and thirdly, combining the sequence A and the sequence B to obtain two completely same preamble sequences. The lead code of the method has the characteristic of conjugate symmetry about respective central points, and has good inhibition effect on flat-top effect. However, the method still has the disadvantage that the preamble is conjugate and symmetrical, so that two large side peaks appear in a short distance from a correct timing position, thereby affecting the accuracy of the generalized frequency division multiplexing system in timing synchronization. Meanwhile, the preamble code of the method has low spectrum efficiency and has the problem of causing spectrum resource waste.
Disclosure of Invention
The invention aims to provide a time-frequency synchronization method of a generalized frequency division multiplexing system based on lead codes with positive and negative polarities aiming at the defects of the prior art, and the method is used for solving the problems that when the coarse symbol timing synchronization is carried out on a receiving sequence, in order to eliminate the flat top effect generated by the lead codes, extra calculation is needed, so that the design complexity is increased, and the lead codes have low frequency spectrum efficiency and cause frequency spectrum resource waste.
The idea of realizing the purpose of the invention is to generate a positive and negative polarity synchronous preamble sequence and add a Tukey window to the positive and negative polarity synchronous preamble sequence, and add the windowed synchronous preamble sequence before the generalized frequency division multiplexing modulation sequence, and use a transmitter of the generalized frequency division multiplexing GFDM to transmit. The sequence received by each receiving point of the receiver of the generalized frequency division multiplexing GFDM is taken as the receiving sequence of the point, and the carrier frequency synchronization and the timing symbol synchronization are realized through the coarse symbol timing synchronization, the frequency offset correction and the fine symbol timing synchronization in sequence.
The method comprises the following specific steps:
(1) generating a synchronization preamble sequence:
(1a) generating a pseudo-random PN sequence, the length of the sequence being:
Figure GDA0003357997830000021
wherein, N represents the total number of subcarriers in each modulated data block of the generalized frequency division multiplexing system;
(1b) generating a positive and negative polarity synchronization preamble sequence, the length of the sequence being: l ═ 2R;
(1c) adding a cyclic prefix to the preamble sequence;
(2) adding a Tukey window to the synchronization preamble sequence:
(2a) generating a Tukey window sequence with the same length as the lead code sequence added with the cyclic prefix;
(2b) performing dot product operation on the lead code sequence and the Tukey window sequence to obtain a windowed synchronous lead code sequence;
(3) sending a modulation sequence loaded with a preamble:
adding the windowed synchronous lead code sequence in front of the generalized frequency division multiplexing modulation sequence to form a modulation sequence loaded with the lead code, and transmitting the modulation sequence by a transmitter of the generalized frequency division multiplexing GFDM;
(4) coarse symbol timing synchronization:
(4a) taking a sequence received by each receiving point of a receiver of the generalized frequency division multiplexing GFDM as a receiving sequence of the point, wherein the length of each receiving sequence is the same as that of a synchronous preamble sequence added with a cyclic prefix;
(4b) calculating the autocorrelation value of each receiving sequence by utilizing an autocorrelation formula, and forming all autocorrelation values into an autocorrelation sequence;
(4c) normalizing the autocorrelation sequence by using a normalization formula, and forming a coarse symbol timing measurement sequence by all normalized autocorrelation values;
(4d) finding out a receiving point corresponding to the maximum value in the coarse symbol timing measurement sequence as a coarse symbol timing synchronization estimation value, wherein the receiving sequence corresponding to the receiving point is a coarse synchronization sequence;
(5) correcting frequency deviation:
(5a) carrying out phase taking operation on the autocorrelation value of the coarse synchronization sequence to obtain the phase of the autocorrelation value;
(5b) dividing the phase of the autocorrelation value by the circumference ratio to obtain a frequency deviation estimation value of the receiving sequence;
(5c) correcting the frequency offset of the received value in each receiving sequence by using a frequency offset correction formula to realize carrier frequency synchronization;
(6) fine symbol timing synchronization:
(6a) calculating the cross-correlation value of each corrected receiving sequence and the synchronous lead code sequence by using a cross-correlation formula, and forming all the cross-correlation values into a cross-correlation sequence;
(6b) performing dot product operation on the autocorrelation sequence and the cross-correlation sequence to obtain a combined measurement sequence;
(6c) and finding out a receiving point corresponding to the maximum value in the combined measurement sequence as a fine symbol timing synchronization estimation value, and taking a receiving sequence corresponding to the receiving point as a receiving sequence after symbol timing synchronization is realized.
Compared with the prior art, the invention has the following advantages:
firstly, the invention uses the positive and negative polarity synchronization lead code sequence, and overcomes the problems that the lead code generates the flat top effect when the prior art carries out coarse symbol timing synchronization on the sampling sequence, the influence of the flat top effect can be eliminated only by extra calculation, the system complexity is increased, and the symbol timing synchronization performance is sharply reduced, so that the design complexity of the invention is lower, and the invention has the advantage of more accurate symbol timing synchronization.
Secondly, the Tukey window is added to the synchronous lead code sequence, so that the problems that two large side peaks appear in a short distance from a correct timing position in the prior art, correct symbol timing synchronization is influenced, and lead code frequency spectrum resources are wasted are solved, and the synchronous lead code sequence has the advantages of higher frequency spectrum efficiency, spectrum resource saving and more accurate symbol timing synchronization.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a simulation of the present invention.
Detailed Description
The present invention will be described in further detail below with reference to the accompanying drawings.
Referring to fig. 1, the implementation steps of the present invention are described in further detail.
Step 1, generating a synchronization preamble sequence.
Generating a pseudo-random PN sequence, the length of the sequence being:
Figure GDA0003357997830000041
where N represents the total number of subcarriers in each modulated data block of the generalized frequency division multiplexing system.
Generating a positive and negative polarity synchronization preamble sequence, the length of the sequence being: l is 2R,
A cyclic prefix is added to the preamble sequence.
And 2, adding a Tukey window to the synchronous lead code sequence.
And generating a Tukey window sequence with the same length as the preamble sequence added with the cyclic prefix.
The Tukey window sequence is obtained according to the following formula:
Figure GDA0003357997830000042
wherein w (k) represents the kth sequence value in the Tukey window sequence, cos (·) represents a cosine function, pi represents a circumference ratio, v represents a wavelet auxiliary sequence, and v ═ m4(35-84m+70m2-20m3) M represents a factor in the wavelet auxiliary sequence, when k is more than or equal to 0 and less than W,
Figure GDA0003357997830000043
when L + Lcp-W≤k＜L+LcpWhen the temperature of the water is higher than the set temperature,
Figure GDA0003357997830000044
Lcpthe length of a cyclic prefix of the synchronous preamble sequence is represented, W represents a Tukey window rising and falling edge width parameter, and the value and L of WcpAre equal in value.
And performing dot product operation on the preamble sequence and the Tukey window sequence to obtain the windowed synchronous preamble sequence.
And 3, sending the modulation sequence loaded with the lead code.
And adding the windowed synchronous lead code sequence before the generalized frequency division multiplexing modulation sequence to form a modulation sequence loaded with the lead code, and transmitting the modulation sequence by a transmitter of the generalized frequency division multiplexing GFDM.
And 4, coarse symbol timing synchronization.
Taking the sequence received by each receiving point of the receiver of the generalized frequency division multiplexing GFDM as the receiving sequence of the point, wherein the length of each receiving sequence is the same as the length of the synchronization preamble sequence added with the cyclic prefix.
And calculating the autocorrelation value of each received sequence by using an autocorrelation formula, and forming all autocorrelation values into an autocorrelation sequence.
The autocorrelation formula is:
Figure GDA0003357997830000051
where ρ istRepresents the autocorrelation value of the received sequence of the t-th reception point, sigma represents the summation operation, rtIndicating the reception point of the tAnd (5) receiving the sequence, wherein i represents the serial number of the received value in the receiving sequence, and the prime mark represents the conjugate operation.
And normalizing the autocorrelation sequence by using a normalization formula, and forming a coarse symbol timing measurement sequence by all normalized autocorrelation values.
The normalization formula is:
Figure GDA0003357997830000052
wherein, mutNormalized autocorrelation value representing the received sequence of the t-th receive point, | · | represents an absolute value operation, rt(x) Represents the xth received value in the received sequence of the tth received point.
Finding out a receiving point corresponding to the maximum value in the coarse symbol timing measurement sequence as a coarse symbol timing synchronization estimation value, wherein the receiving sequence corresponding to the receiving point is a coarse synchronization sequence;
and 5, correcting the frequency offset.
And carrying out phase taking operation on the autocorrelation value of the coarse synchronization sequence to obtain the phase of the autocorrelation value.
The phase taking operation is as follows:
Figure GDA0003357997830000053
wherein theta represents the phase value of the autocorrelation value of the coarse synchronization sequence, and the angle represents the phase taking operation,
Figure GDA0003357997830000054
is shown as
Figure GDA0003357997830000061
The autocorrelation values of the received sequence of the individual received points,
Figure GDA0003357997830000062
is equal to the coarse symbol timing synchronization estimate.
And performing division operation on the phase of the autocorrelation value and the circumferential rate to obtain a frequency offset estimation value of the receiving sequence.
And correcting the frequency offset of the received value in each receiving sequence by using the following frequency offset correction formula to realize carrier frequency synchronization:
Figure GDA0003357997830000063
wherein r ist' (j) denotes the j-th reception value of the reception sequence of the t-th reception point after the correction of the frequency offset, the value of j is equal to the value of x, x denotes the multiplication operation, e denotes the exponential operation with the natural constant as the base,
Figure GDA0003357997830000064
representing the frequency offset estimate.
And 6, fine symbol timing synchronization.
Calculating the cross-correlation value of each corrected receiving sequence and the synchronous lead code sequence by using the following cross-correlation formula, and forming all the cross-correlation values into a cross-correlation sequence:
Figure GDA0003357997830000065
wherein σtAnd p (d) represents the d sequence value in the synchronous preamble sequence, and the value of d is correspondingly equal to j.
And performing dot product operation on the autocorrelation sequence and the cross-correlation sequence to obtain a combined measurement sequence.
And finding out a receiving point corresponding to the maximum value in the combined measurement sequence as a fine symbol timing synchronization estimation value, and taking a receiving sequence corresponding to the receiving point as a receiving sequence after symbol timing synchronization is realized.
The effect of the present invention can be further demonstrated by the following simulation.
1. And (5) simulating experimental conditions.
The software platform of the simulation experiment of the invention is as follows: windows 10 operating system and Matlab R2019 b.
2. And (5) simulating content and result analysis.
The simulation experiments of the invention are three.
2.1 simulation experiment 1 is a simulation of the mean square error of timing synchronization estimation of a generalized frequency division multiplexing GFDM system.
The digital modulation mode of the generalized frequency division multiplexing GFDM system used in the simulation experiment 1 of the present invention employs QPSK, the number of slots of the preamble of the generalized frequency division multiplexing GFDM is 2, the number of subcarriers is 128, the length of the cyclic prefix is 32, the shaping filter of the generalized frequency division multiplexing GFDM system is a rectangular filter, the length of the timing deviation is 128, the normalized frequency offset is 0.5, the transmission channel environment is a rayleigh fading channel, and the signal-to-noise ratio is from 1 to 20.
The simulation experiment 1 of the present invention adopts the method of the present invention and two existing techniques to obtain the mean square error values of the timing synchronization estimation under 20 signal-to-noise ratios, and then plots the relationship between the obtained mean square error values of the timing synchronization estimation and the signal-to-noise ratios into three curves as shown in (a) of fig. 2.
In simulation experiment 1, two prior arts are used:
prior art 1 refers to a method for coarse symbol timing synchronization of a sampling sequence, which is proposed in the patent application document "a generalized frequency division multiplexing time-frequency synchronization method for correcting large frequency offset" (application No. 2018101172643, application publication No. CN108366032A) applied by the university of electrical science and technology of west ampere.
The prior art 2 refers to that wu hong et al propose an improved preamble-based generalized frequency division multiplexing system time-frequency synchronization method in an "improved GFDM time-frequency synchronization algorithm" (telecommunication technology, 2016,56(12): 1322-.
2.2 simulation experiment 2 is a simulation of the mean square error of the frequency offset estimation of the generalized frequency division multiplexing GFDM system.
The parameters of the generalized frequency division multiplexing GFDM system used in the simulation experiment 2 of the invention are the same as those of the simulation experiment 1.
The simulation experiment 2 of the present invention adopts the method of the present invention and two existing techniques to obtain the mean square error values of the frequency offset estimation under 20 signal-to-noise ratios, and then plots the relationship between the obtained mean square error values of the frequency offset estimation and the signal-to-noise ratios into three curves as shown in (b) of fig. 2.
In simulation experiment 2, the two prior arts used are the same as in simulation experiment 1.
2.3 simulation experiment 3 is a simulation of the synchronization preamble power spectral density of a generalized frequency division multiplexing GFDM system.
The generalized frequency division multiplexing GFDM preamble slot number used in simulation experiment 3 is 2, the subcarrier number is 128, the available subcarrier number is 60, the frequency domain sampling point number is 288, there is no influence of the channel environment, and other parameters are the same as those in simulation experiment 1.
The simulation experiment 3 of the present invention is to obtain the power spectrum density value of the synchronization preamble at 288 frequency domain sampling points by using the method of the present invention and the prior art 2, and then plot the relationship between the obtained power spectrum density value of the synchronization preamble and the frequency domain sampling points into two curves as shown in (c) of fig. 2.
In simulation experiment 3, prior art 2 used was the same as simulation experiment 1.
The effect of the present invention will be further described with reference to the simulation diagram of fig. 2.
The abscissa in fig. 2 (a) represents the signal-to-noise ratio in dB of the GFDM system and the ordinate represents the mean square error of the timing synchronization estimate. The curve marked by a circle represents a relation curve between the mean square error of the timing synchronization estimation obtained by simulation in the prior art 1 and the signal-to-noise ratio, the curve marked by a square represents a relation curve between the mean square error of the timing synchronization estimation obtained by simulation in the prior art 2 and the signal-to-noise ratio, and the curve marked by an above triangle represents a relation curve between the mean square error of the timing synchronization estimation obtained by the method provided by the invention and the signal-to-noise ratio.
As can be seen from (a) in fig. 2: the mean square error of 20 timing synchronization estimation obtained by the method of the invention is continuously reduced along with the increase of the signal-to-noise ratio. Under the condition of the same signal-to-noise ratio, the mean square error of the timing synchronization estimation obtained by the method is always smaller than that obtained by simulation of two prior arts.
The abscissa in fig. 2 (b) represents the signal-to-noise ratio in dB of the GFDM system and the ordinate represents the mean square error of the frequency offset estimation. The curve marked by a circle represents the curve of the relationship between the mean square error of the frequency offset estimation and the signal-to-noise ratio obtained by adopting the prior art 1, the curve marked by a square represents the curve of the relationship between the mean square error of the frequency offset estimation and the signal-to-noise ratio obtained by adopting the prior art 2, and the curve marked by an above triangle represents the curve of the relationship between the mean square error of the frequency offset estimation and the signal-to-noise ratio obtained by adopting the method provided by the invention.
As can be seen from fig. 2 (b): under the condition of low signal-to-noise ratio, the frequency offset estimation mean square error obtained by the method of the invention is not much different from that of the two existing methods, but under the condition of high signal-to-noise ratio, the frequency offset estimation error obtained by the method of the invention is less than that of the mean square error obtained by simulation of the two existing techniques.
The abscissa of (c) in fig. 2 represents the frequency domain sampling points and the ordinate represents the power spectral density in dB. The curve marked by a circle represents a relationship curve between the power spectral density and the frequency domain sampling points obtained by adopting the lead code in the prior art 2, and the curve marked by the above triangle represents a relationship curve between the power spectral density and the frequency domain sampling points obtained by adopting the lead code provided by the invention.
As can be seen from (c) in fig. 2: the power spectrum density attenuation degree of the lead code obtained by the method is larger, the higher frequency spectrum efficiency is realized, and the frequency spectrum resource is saved.

Claims (8)

1. A generalized frequency division multiplexing system time-frequency synchronization method based on positive and negative polarity lead codes is characterized in that positive and negative polarity synchronization lead code sequences are generated, and Tukey windows are added to the synchronization lead code sequences, and the method specifically comprises the following steps:
(1) generating a synchronization preamble sequence:
(1a) generating a pseudo-random PN sequence, the length of the sequence being:
Figure FDA0003357997820000011
wherein, N represents the total number of subcarriers in each modulated data block of the generalized frequency division multiplexing system;
(1b) generating a positive and negative polarity synchronization preamble sequence, the length of the sequence being: l ═ 2R;
(1c) adding a cyclic prefix to the preamble sequence;
(2) adding a Tukey window to the synchronization preamble sequence:
(2a) generating a Tukey window sequence with the same length as the lead code sequence added with the cyclic prefix;
(2b) performing dot product operation on the lead code sequence and the Tukey window sequence to obtain a windowed synchronous lead code sequence;
(3) sending a modulation sequence loaded with a preamble:
adding the windowed synchronous lead code sequence in front of the generalized frequency division multiplexing modulation sequence to form a modulation sequence loaded with the lead code, and transmitting the modulation sequence by a transmitter of the generalized frequency division multiplexing GFDM;
(4) coarse symbol timing synchronization:
(4a) taking a sequence received by each receiving point of a receiver of the generalized frequency division multiplexing GFDM as a receiving sequence of the point, wherein the length of each receiving sequence is the same as that of a synchronous preamble sequence added with a cyclic prefix;
(4b) calculating the autocorrelation value of each receiving sequence by utilizing an autocorrelation formula, and forming all autocorrelation values into an autocorrelation sequence;
(4c) normalizing the autocorrelation sequence by using a normalization formula, and forming a coarse symbol timing measurement sequence by all normalized autocorrelation values;
(4d) finding out a receiving point corresponding to the maximum value in the coarse symbol timing measurement sequence as a coarse symbol timing synchronization estimation value, wherein the receiving sequence corresponding to the receiving point is a coarse synchronization sequence;
(5) correcting frequency deviation:
(5a) carrying out phase taking operation on the autocorrelation value of the coarse synchronization sequence to obtain the phase of the autocorrelation value;
(5b) dividing the phase of the autocorrelation value by the circumference ratio to obtain a frequency deviation estimation value of the receiving sequence;
(5c) correcting the frequency offset of the received value in each receiving sequence by using a frequency offset correction formula to realize carrier frequency synchronization;
(6) fine symbol timing synchronization:
(6a) calculating the cross-correlation value of each corrected receiving sequence and the synchronous lead code sequence by using a cross-correlation formula, and forming all the cross-correlation values into a cross-correlation sequence;
(6b) performing dot product operation on the autocorrelation sequence and the cross-correlation sequence to obtain a combined measurement sequence;
(6c) and finding out a receiving point corresponding to the maximum value in the combined measurement sequence as a fine symbol timing synchronization estimation value, and taking a receiving sequence corresponding to the receiving point as a receiving sequence after symbol timing synchronization is realized.
2. The time-frequency synchronization method for generalized frequency division multiplexing system based on preambles with positive and negative polarities as claimed in claim 1, wherein the preamble sequence with positive and negative polarities in step (1b) is composed of four pseudo-random PN sequences with equal absolute values, wherein the first and second sequences have positive polarities and the third and fourth sequences have negative polarities.
3. The generalized frequency-division multiplexing system time-frequency synchronization method based on the preamble with positive and negative polarities of claim 1, wherein the Tukey window sequence in step (2a) is obtained according to the following formula:
Figure FDA0003357997820000021
wherein w (k) represents the kth sequence value in the Tukey window sequence, cos (·) represents a cosine function, pi represents a circumference ratio, v represents a wavelet auxiliary sequence, and v ═ m4(35-84m+70m2-20m3) M represents a factor in the wavelet auxiliary sequence, when k is more than or equal to 0 and less than W,
Figure FDA0003357997820000022
when L + Lcp-W≤k＜L+LcpWhen the temperature of the water is higher than the set temperature,
Figure FDA0003357997820000023
Lcpthe length of a cyclic prefix of the synchronous preamble sequence is represented, W represents a Tukey window rising and falling edge width parameter, and the value and L of WcpAre equal in value.
4. The method for time-frequency synchronization of a generalized frequency division multiplexing system based on preambles with positive and negative polarities according to claim 1, wherein said autocorrelation formula in step (4b) is as follows:
Figure FDA0003357997820000031
where ρ istRepresents the autocorrelation value of the received sequence of the t-th reception point, sigma represents the summation operation, rtIndicating the received sequence of the t-th received point, i indicating the sequence number of the received value in the received sequence, and the superscript indicates the conjugate operation.
5. The method for time-frequency synchronization of generalized frequency division multiplexing system based on preambles with positive and negative polarities as claimed in claim 4, wherein said normalization formula in step (4c) is:
Figure FDA0003357997820000032
wherein, mutNormalized autocorrelation value representing the received sequence of the t-th receive point, | · | represents an absolute value operation, rt(x) Represents the xth received value in the received sequence of the tth received point.
6. The method for time-frequency synchronization of generalized frequency division multiplexing system based on preambles with positive and negative polarities according to claim 1, wherein said phase-taking operation in step (5a) is as follows:
Figure FDA0003357997820000033
wherein theta represents the phase value of the autocorrelation value of the coarse synchronization sequence, and the angle represents the phase taking operation,
Figure FDA0003357997820000034
is shown as
Figure FDA0003357997820000035
The autocorrelation values of the received sequence of the individual received points,
Figure FDA0003357997820000036
is equal to the coarse symbol timing synchronization estimate.
7. The method for time-frequency synchronization of a generalized frequency division multiplexing system based on preambles with positive and negative polarities according to claim 5, wherein said frequency offset correction formula in step (5c) is:
Figure FDA0003357997820000041
wherein r ist' (j) denotes the j-th reception value of the reception sequence of the t-th reception point after the correction of the frequency offset, the value of j is equal to the value of x, x denotes the multiplication operation, e denotes the exponential operation with the natural constant as the base,
Figure FDA0003357997820000042
representing the frequency offset estimate.
8. The generalized frequency-division multiplexing system time-frequency synchronization method based on the preamble with positive and negative polarities as claimed in claim 7, wherein the cross-correlation formula in step (6a) is:
Figure FDA0003357997820000043
wherein σtAnd p (d) represents the d sequence value in the synchronous preamble sequence, and the value of d is correspondingly equal to j.
CN202110054896.1A 2021-01-15 2021-01-15 Generalized frequency division multiplexing system time-frequency synchronization method based on positive and negative lead codes Active CN112910815B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110054896.1A CN112910815B (en) 2021-01-15 2021-01-15 Generalized frequency division multiplexing system time-frequency synchronization method based on positive and negative lead codes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110054896.1A CN112910815B (en) 2021-01-15 2021-01-15 Generalized frequency division multiplexing system time-frequency synchronization method based on positive and negative lead codes

Publications (2)

Publication Number Publication Date
CN112910815A CN112910815A (en) 2021-06-04
CN112910815B true CN112910815B (en) 2022-03-04

Family

ID=76114655

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110054896.1A Active CN112910815B (en) 2021-01-15 2021-01-15 Generalized frequency division multiplexing system time-frequency synchronization method based on positive and negative lead codes

Country Status (1)

Country Link
CN (1) CN112910815B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113543303B (en) * 2021-06-30 2022-10-21 紫光展锐(重庆)科技有限公司 Synchronization method, synchronization device, chip and module equipment

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110086742A (en) * 2013-07-04 2019-08-02 索尼公司 For restoring the receiver and method of the payload data in reception signal

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9998317B2 (en) * 2015-06-11 2018-06-12 Samsung Electronics Co., Ltd Method of detecting synchronization signal in wireless communication system
CN108366032B (en) * 2018-02-06 2020-04-07 西安电子科技大学 Generalized frequency division multiplexing time-frequency synchronization method for correcting large frequency offset
CN109660478B (en) * 2018-12-10 2021-01-29 长安大学 Timing frequency synchronization method based on improved Park frequency domain training sequence

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110086742A (en) * 2013-07-04 2019-08-02 索尼公司 For restoring the receiver and method of the payload data in reception signal

Also Published As

Publication number Publication date
CN112910815A (en) 2021-06-04

Similar Documents

Publication Publication Date Title
RU2365055C2 (en) Exact coming into synchronism
US20090003308A1 (en) Methods and apparatus for generating synchronization/pilot sequences for embedding in wireless signals
CN110636024B (en) 5G waveform system synchronization method based on index modulation
CN1277359C (en) Method for estimating carrier, frequency shifts of orthogonal FDM communication system
CN104125188B (en) OFDM (Orthogonal Frequency Division Multiplexing) frequency synchronizing method based on Zadoff-Chu sequence
CN113518052B (en) Robust frequency offset estimation method and device for orthogonal frequency division multiplexing communication
CN106685883B (en) Preamble symbol receiving apparatus
CN111683034A (en) OFDM-based large Doppler wireless communication time-frequency synchronization method
CN101277288A (en) Method of synchronization of orthogonal frequency division multiplexing system frequency
CN101083645A (en) Low complexity OFDM quick synchronising method
CN101212440A (en) Carrier frequency deviation estimation method and device
CN1574821A (en) TDS-OFDM receiver and signal processing method thereof
US20090092038A1 (en) Timing-offset estimation in modulated signals using weighted correlation values
CN107318157B (en) Timing error estimation method based on leader sequence
CN100493057C (en) Channel estimation method for solving OFDM interception position hopping using rotating technology
CN112910815B (en) Generalized frequency division multiplexing system time-frequency synchronization method based on positive and negative lead codes
CN113315541A (en) Pseudo-random phase sequence spread spectrum modulation method
EP2194666A1 (en) Radio communication device, and reception quality estimating method
WO2017121412A1 (en) Data modulation for use in multi-carrier system, demodulation method, frame generation method, and node
CN107911324B (en) Frequency offset and phase offset estimation method in single-carrier interleaved frequency division multiple access system
CN111107028B (en) PSS and SSS combined frequency offset estimation method for 5G system
CN110995630B (en) Frequency offset correction method of narrow-band communication system suitable for mixed running of multi-level trains
CN1291561C (en) Method for obtaining rough estimate of frequency diviation by frequency domain PV sequence guidance
WO2011117673A1 (en) Preamble structure for time-frequency acquisition in ofdm systems with multiple strong narrowband interference
CN105119861A (en) BER improvement method of interleaved carrier index modulation N-order continuous OFDM system

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant