CN111614593A - Synchronization method for resisting single-tone interference of OFDM system - Google Patents

Synchronization method for resisting single-tone interference of OFDM system Download PDF

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CN111614593A
CN111614593A CN202010376424.3A CN202010376424A CN111614593A CN 111614593 A CN111614593 A CN 111614593A CN 202010376424 A CN202010376424 A CN 202010376424A CN 111614593 A CN111614593 A CN 111614593A
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interference
signal
synchronization
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synchronous
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CN111614593B (en
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魏国庆
刘永嘉
范朝元
周继华
赵涛
苏凌旭
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Chongqing Jinmei Communication Co Ltd
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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
    • H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
    • H04L27/2691—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation involving interference determination or cancellation
    • 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
    • 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
    • H04L27/2681—Details of algorithms characterised by constraints
    • H04L27/2688—Resistance to perturbation, e.g. noise, interference or fading
    • 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
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Abstract

The invention discloses a method for anti-single tone interference synchronization under an Orthogonal Frequency Division Multiplexing (OFDM) system, which comprises the following steps: 1) filtering the received signal in a sliding window to filter the influence of direct current interference; 2) before receiving the effective signal, counting the average power of interference and noise, and estimating the amplitude of the interference noise; 3) the initial synchronization correlation process is to store the calculated total signal energy, calculate the current signal-to-interference-and-noise ratio, feed back to the transmitting end and adjust the power of the transmitting end so as to meet the requirements of system synchronization and minimum error rate; 4) synchronous correlation calculation, namely filtering the peak value calculated by the single tone signal according to the position relation between the signal energy of the auxiliary data AGC and the correlation peak value, estimating the synchronous position, FFT (fast Fourier transform) and channel estimation, and calculating the frequency point position of the single tone interference signal through a channel coefficient; 5) reshaping the single-tone signal according to the interference amplitude and the interference frequency offset; 6) in the synchronous tracking stage, a received signal is subtracted from the remolded single-tone signal to obtain a new receiving end signal, synchronous correlation calculation is carried out, a synchronous peak value is compensated, and the influence of interference on the synchronous peak value is reduced; the invention solves the problems of error synchronization and synchronization loss caused by direct current offset interference and single tone interference in the bandwidth of the OFDM system, reduces the false alarm probability of synchronization and improves the system performance.

Description

Synchronization method for resisting single-tone interference of OFDM system
Technical Field
The invention belongs to the technical field of wireless communication, and particularly relates to a synchronization method for resisting single-tone interference of an OFDM system.
Background
Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier modulation scheme that overcomes frequency selective fading of the channel by reducing and eliminating the effects of inter-symbol interference. OFDM is very sensitive to synchronization errors, and especially in multipath fading channels, symbol timing errors can destroy orthogonality between subcarriers, causing severe inter-symbol interference (ISI).
The synchronization tasks of the OFDM system comprise time synchronization and carrier frequency synchronization, the time synchronization aims to determine the starting position of an OFDM symbol so as to carry out multi-carrier demodulation on data, and the carrier frequency synchronization aims to solve the problems of signal amplitude attenuation and subcarrier spacing interference caused by frequency inconsistency between a transmitter and a receiver.
Many documents already analyze and research timing synchronization methods of OFDM, but the existing methods lack measures against interference, and the synchronization false alarm rate is too high in an interference environment, resulting in serious degradation of system communication performance.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a synchronization method for OFDM system to resist single-tone interference, which solves the problem that the in-band single-tone interference in the system affects synchronization.
The invention is realized by the following technical scheme:
a synchronization method for OFDM system to resist single tone interference includes,
after anti-interference processing is carried out on a received radio frequency signal by modules of IQ offset interference filtering, power adjustment, synchronous correlation, interference point searching, interference signal remodeling, filtering and the like, the influence of interference on synchronization is eliminated, and a correct synchronization position is estimated.
In the IQ offset interference filtering, in the initial blind synchronization process of the system, the time domain filtering processing is carried out on the radio frequency signal received by the receiver, the direct current offset interference component in the signal is removed, and the error correlation caused by the direct current offset interference is avoided;
the power adjustment is to count the average power of interference and noise in a coherent time before receiving the effective signal, estimate the amplitude of the interference noise according to the power and store the amplitude; according to the total energy and the interference signal energy calculated in the synchronous correlation process, calculating a signal-to-interference-and-noise ratio, feeding back to the transmitting end, and adjusting the power of the transmitting end to meet the requirements of the system on the lowest synchronization probability and the lowest error rate;
in the synchronous correlation, in the initial blind synchronization stage, a correlation measurement function is calculated, the position of a peak value is judged, the peak value is normalized to meet a normalization threshold condition, meanwhile, a synchronization condition is set according to the relation between the signal energy of the auxiliary data AGC and the position of the correlation peak value, the peak value caused by a single tone signal is filtered, and the synchronization position is correctly estimated;
searching the interference point, after the initial synchronization is successful, performing FFT (fast Fourier transform) and channel estimation calculation, calculating the total energy and average energy of a channel coefficient through the channel coefficient, determining the interference point according to the interference setting condition, calculating the frequency offset of the single-tone interference signal according to the interference point, and storing the frequency offset;
and the interference signal is reshaped and filtered, a synchronous tracking stage is entered, the reshaped single-tone interference signal is subtracted from the received signal, the interference of the single-tone signal to the synchronization process is reduced, and the synchronization position is estimated.
A synchronization method for OFDM system to resist single tone interference, the method comprising:
step s1, establishing a sliding window, taking the data mean value in the window, subtracting the mean value of the time domain signal in the sliding window from the received radio frequency signal, filtering the interference caused by IQ amplitude deviation of the received signal,
Figure 140405DEST_PATH_IMAGE002
wherein, in the step (A),
Figure 597931DEST_PATH_IMAGE004
step s2, where the index of the time domain signal in the sliding window is defined, WL is the length of the established sliding window, r (n) is the received radio frequency signal, and n is the index of the received signal;
step s2, before receiving the effective signal, processing the signal r (n) at the receiving end,
Figure 146724DEST_PATH_IMAGE006
where Tc is the coherence time of the energy statistic,
Figure 47815DEST_PATH_IMAGE008
is a signal
Figure 314848DEST_PATH_IMAGE010
K is the number of statistical energies. Taking the minimum value as the energy of the interference signal,
Figure 513749DEST_PATH_IMAGE012
and the amplitude of the interfering signal is calculated,
Figure 979365DEST_PATH_IMAGE014
proceeding to step s 3;
step s3, roughly calculating the signal-to-interference-and-noise ratio of the received signal, returning to the originating terminal for power adjustment, the concrete steps include,
in a synchronous correlation process, step s31, the total average energy of the signal is calculated,
Figure 238308DEST_PATH_IMAGE016
where d is the delay length of the received signal,
Figure 805687DEST_PATH_IMAGE018
n is the correlation window length, fftsize is the FFT length, go to step s 32;
step s32, calculating the signal to interference plus noise ratio,
Figure 542699DEST_PATH_IMAGE020
proceeding to step s 33;
step s33, judging whether the current signal meets the system condition:
Figure 66084DEST_PATH_IMAGE022
wherein, in the step (A),
Figure 558245DEST_PATH_IMAGE024
is the error rate corresponding to the signal-to-interference ratio,
Figure 534291DEST_PATH_IMAGE026
in order to be the expected error rate of the system,
Figure 902692DEST_PATH_IMAGE028
a synchronization false alarm probability expected for the system; if the condition is satisfied, go to step s 4; otherwise, feeding back to the transmitting end, increasing the power of the transmitting end signal, and entering the step s 1;
step s4, entering a synchronization module for timing synchronization, specifically including,
step s41, calculating a synchronization-related metric function
Figure 608480DEST_PATH_IMAGE030
；
Step s42, the correlation peak is found,
Figure 943646DEST_PATH_IMAGE032
the position of the synchronization position,
Figure 485617DEST_PATH_IMAGE034
normalizing the peak value;
step s43, setting synchronous decision condition according to the position relation of auxiliary data AGC energy and correlation peak value, calculating data ratio
Figure 564431DEST_PATH_IMAGE036
，
Figure 124726DEST_PATH_IMAGE038
，
Figure 630793DEST_PATH_IMAGE040
Wherein the content of the first and second substances,
Figure 660060DEST_PATH_IMAGE042
for the energy at the position of the AGC,
Figure 542566DEST_PATH_IMAGE044
in order to be the energy of the correlation,
Figure 957367DEST_PATH_IMAGE046
which is the position of the AGC symbol, symLen is the AGC symbol length,
Figure 899915DEST_PATH_IMAGE048
is the set synchronization decision condition. If the synchronization decision condition is satisfied, the synchronization is successful, and the step s5 is entered; otherwise, discarding, and re-entering step s 1;
step s5, finding the position of the interference point, which includes the specific steps,
step s51, calculating a channel coefficient, H;
step s52, counting the total energy and average energy in the frequency domain of the channel coefficients,
Figure 337849DEST_PATH_IMAGE050
，
Figure 571516DEST_PATH_IMAGE052
where Nc is the subcarrier length;
step s53, estimating energy
Figure 44085DEST_PATH_IMAGE054
Maximum value of
Figure 891956DEST_PATH_IMAGE056
And the position is recorded,
Figure 879503DEST_PATH_IMAGE058
；
step s54, calculating the number of sign bits of the total energy and the average energy, respectively,
Figure 103811DEST_PATH_IMAGE060
，
Figure 241007DEST_PATH_IMAGE062
and calculating the difference:
Figure 525358DEST_PATH_IMAGE064
；
step s55, setting an interference signal threshold value,
Figure 937885DEST_PATH_IMAGE066
if, if
Figure 762621DEST_PATH_IMAGE068
If so, then an interference signal is present, and the interference position is calculated:
Figure 944204DEST_PATH_IMAGE070
the interference frequency points are:
Figure 212505DEST_PATH_IMAGE072
，
Figure 112328DEST_PATH_IMAGE074
for subcarrier spacing, an interference phase coefficient is established:
Figure 740756DEST_PATH_IMAGE076
，
Figure 776845DEST_PATH_IMAGE078
DL is time domain data length; if the condition is not met, no interference signal exists; proceeding to step s 6;
step s6, according to the estimated interference signal amplitude and phase, the interference signal is reshaped,
Figure 216047DEST_PATH_IMAGE080
wherein
Figure 603166DEST_PATH_IMAGE082
In order to be able to measure the amplitude of the interference,
Figure 707389DEST_PATH_IMAGE084
in order to disturb the phase of the signal,
Figure 925880DEST_PATH_IMAGE086
，
Figure 722935DEST_PATH_IMAGE088
for the number of system sampling points, go to step s 7;
at step s7, the system enters a synchronization tracking phase, the interference signal is subtracted from the received signal,
Figure 144820DEST_PATH_IMAGE090
wherein, in the step (A),
Figure 318313DEST_PATH_IMAGE091
，
Figure 391311DEST_PATH_IMAGE088
counting the number of sampling points of the system; reducing single-tone interference of the received signal causes attenuation of amplitude and phase.
Drawings
FIG. 1 is a system process flow diagram of the present invention;
FIG. 2 illustrates a received signal of DC offset jammer;
FIG. 3 simultaneous correlation peaks under single tone interference;
FIG. 4 is a graph of sync correlation peak versus energy for single tone interference;
FIG. 5 frequency domain interferer point location;
fig. 6 comparison of the pre-and post-synchronization correlation peaks for interference point cancellation.
Detailed Description
To make the objects and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings and examples.
Referring to fig. 1, the specific implementation steps of the present invention are as follows:
step 1, establishing a sliding window, taking the average value of data in the window, subtracting the average value of time domain signals in the sliding window from a received radio frequency signal,
Figure 359267DEST_PATH_IMAGE002
taking window length WL =8, IQ amplitude shifts the interfered data as shown in fig. 2;
step 2, counting interference and noise, and setting the number of coherent points
Figure 455399DEST_PATH_IMAGE093
And the interference energy is calculated,
Figure DEST_PATH_IMAGE095
the interference amplitude is:
Figure DEST_PATH_IMAGE097
；
step 3, roughly calculating the signal-to-interference-and-noise ratio of the received signal, returning to the sending end for power adjustment, specifically comprising,
in the synchronous correlation process, step 31, the total average energy of the signal is calculated,
Figure 779720DEST_PATH_IMAGE016
wherein, in the step (A),
Figure 910487DEST_PATH_IMAGE018
，
Figure DEST_PATH_IMAGE099
，
Figure DEST_PATH_IMAGE101
；
step 32, calculating the signal to interference plus noise ratio,
Figure 862393DEST_PATH_IMAGE020
as shown in fig. 3, under different snr conditions, the degree of attenuation of the synchronization peak is different;
step 33, setting parameters:
Figure DEST_PATH_IMAGE103
in order to be the expected error rate of the system,
Figure DEST_PATH_IMAGE105
a synchronization false alarm probability expected for the system; judging whether the current signal meets the system condition:
Figure 321188DEST_PATH_IMAGE106
if the condition is met, entering the step 4; otherwise, feeding back to the transmitting end, improving the signal power of the transmitting end, and entering the step 1;
step 4, entering a synchronization module to perform timing synchronization processing, specifically comprising the steps of,
step 41, calculating a metric function of synchronization correlation
Figure 570903DEST_PATH_IMAGE030
；
In step 42, the correlation peak is found,
Figure 618494DEST_PATH_IMAGE032
the position of the synchronization position,
Figure DEST_PATH_IMAGE107
normalizing the peak value, wherein the threshold value of the normalized peak value is 0.6;
step 43, according to the position relationship between the auxiliary data AGC energy and the correlation peak value, as shown in FIG. 4, setting the synchronization decision condition
Figure DEST_PATH_IMAGE109
Calculating the data ratio
Figure 741302DEST_PATH_IMAGE036
If the synchronization judgment condition is met, the synchronization is successful, and the step 5 is entered; otherwise abandon, enter step 1 again;
step 5, searching the position of the interference point, which comprises the specific steps of,
step 51, calculating a channel coefficient, H, as shown in fig. 5;
step 52, counting the total energy and the average energy in the frequency domain of the channel coefficient,
Figure 812026DEST_PATH_IMAGE050
，
Figure 927749DEST_PATH_IMAGE052
wherein, in the step (A),
Figure DEST_PATH_IMAGE111
frequency domain subcarrier length;
step s53, estimating energy
Figure 577649DEST_PATH_IMAGE054
The maximum value of (a) is,
Figure 58309DEST_PATH_IMAGE056
and the position is recorded,
Figure 350750DEST_PATH_IMAGE058
；
step s54, calculating the number of sign bits of the total energy and the average energy, respectively,
Figure 270164DEST_PATH_IMAGE060
，
Figure 964451DEST_PATH_IMAGE062
and calculating the difference:
Figure 429062DEST_PATH_IMAGE064
；
step s55, setting an interference signal threshold value,
Figure DEST_PATH_IMAGE113
if, if
Figure 536695DEST_PATH_IMAGE068
If so, then an interference signal is present, and the interference position is calculated:
Figure DEST_PATH_IMAGE115
the interference frequency points are:
Figure 931904DEST_PATH_IMAGE116
，
Figure 293746DEST_PATH_IMAGE118
，
Figure 381788DEST_PATH_IMAGE119
，
Figure 711138DEST_PATH_IMAGE120
，
Figure DEST_PATH_IMAGE122
(ii) a If the condition is not met, no interference signal exists; entering step 6;
and step 6, the interference signal is reshaped,
Figure 644459DEST_PATH_IMAGE080
wherein
Figure 126387DEST_PATH_IMAGE123
In order to be able to measure the amplitude of the interference,
Figure DEST_PATH_IMAGE124
in order to disturb the phase of the signal,
Figure 447647DEST_PATH_IMAGE086
，
Figure DEST_PATH_IMAGE126
entering step 7;
step 7, the system enters into the synchronous tracking stage, the interference signal is subtracted from the received signal, and the synchronous position is calculated by synchronous correlation, as shown in figure 6,
Figure 740658DEST_PATH_IMAGE127
wherein, in the step (A),
Figure 743249DEST_PATH_IMAGE086
，
Figure 266634DEST_PATH_IMAGE126
。
in summary, the above description is only a preferred example of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. A synchronization method for OFDM system to resist single tone interference is characterized in that,
after anti-interference processing is carried out on a received radio frequency signal by modules of IQ offset interference filtering, power adjustment, synchronous correlation, interference point searching, interference signal remodeling, filtering and the like, the influence of interference on synchronization is eliminated, and a correct synchronization position is estimated;
the IQ offset interference filtering module carries out time domain filtering processing on the radio frequency signal received by the receiver in the initial blind synchronization process of the system, removes direct current offset interference components in the signal and avoids error correlation caused by direct current offset interference;
the power adjustment is to count the average power of interference and noise in a time period before receiving the effective signal, estimate the amplitude of the interference noise according to the power and store the amplitude; according to the total energy and the interference signal energy calculated in the synchronous correlation process, calculating a signal-to-interference-and-noise ratio, feeding back to the transmitting end, and adjusting the power of the transmitting end to meet the requirements of the system on the lowest synchronization probability and the lowest error rate;
the synchronization module calculates a correlation measurement function, judges the position of a peak value, normalizes the peak value to meet a normalization threshold condition, sets a synchronization condition according to the position relation between the signal energy of the auxiliary data AGC and the correlation peak value, filters the peak value caused by a single tone signal and correctly estimates the synchronization position;
searching the interference point, after the initial synchronization is successful, performing FFT (fast Fourier transform) and channel estimation calculation, calculating the total energy and average energy of a channel coefficient through the channel coefficient, determining the interference point according to the interference setting condition, calculating the frequency offset of the single-tone interference signal according to the interference point, and storing the frequency offset;
and the interference signal is reshaped and filtered, a synchronous tracking stage is entered, the reshaped single-tone interference signal is subtracted from the received signal, the interference of the single-tone signal to the synchronization process is reduced, and the synchronization position is estimated.
2. Filter processing method according to claim 1, characterized in that the received radio frequency signal is subtracted by a sliding windowThe average value of the intra-oral time domain signal,
Figure 758032DEST_PATH_IMAGE002
wherein, in the step (A),
Figure 937341DEST_PATH_IMAGE004
the index of the time domain signal in the sliding window, WL the length of the established sliding window, r (n) the received radio frequency signal, and n the index of the received signal.
3. The method of claim 1, wherein the received signal r (n) is processed before receiving the effective signal,
Figure 412797DEST_PATH_IMAGE005
where Tc is the coherence time of the energy statistic,
Figure 790689DEST_PATH_IMAGE006
is a signal
Figure 329117DEST_PATH_IMAGE007
K is the number of statistical energies; taking the minimum value as the energy of the interference signal,
Figure 730143DEST_PATH_IMAGE008
and the amplitude of the interfering signal is calculated,
Figure 74537DEST_PATH_IMAGE009
。
4. the power adjustment of claim 1, characterized in that the embodied steps comprise:
4.1 during the synchronous correlation process, the total average energy of the signal is calculated,
Figure 323246DEST_PATH_IMAGE010
wherein d is the received signalDelay length, N is correlation window length;
4.2 calculating the signal-to-interference-and-noise ratio according to a formula,；
4.3 according to the signal-to-interference-and-noise ratio, judging whether the system condition is met:
Figure 923828DEST_PATH_IMAGE012
wherein, in the step (A),
Figure 806333DEST_PATH_IMAGE013
is the error rate corresponding to the signal-to-interference ratio,
Figure 96500DEST_PATH_IMAGE014
in order to be the expected error rate of the system,
Figure 773469DEST_PATH_IMAGE015
a synchronization false alarm probability expected for the system; if the conditions are met, entering step 5; otherwise, feeding back to the transmitting end to improve the signal power of the transmitting end.
5. The synchronous peak search of claim 1, wherein the detailed implementation steps comprise:
5.1 computing the metric function of the synchronization correlation
Figure 211404DEST_PATH_IMAGE016
；
5.2 the correlation peak is looked up,
Figure 772966DEST_PATH_IMAGE017
the position of the synchronization position,
Figure 979957DEST_PATH_IMAGE018
normalizing the peak value;
5.3 setting synchronous decision condition according to the position relation of AGC energy and related peak value,
Figure 31089DEST_PATH_IMAGE019
，
Figure 956320DEST_PATH_IMAGE020
，
Figure 118311DEST_PATH_IMAGE021
wherein, in the step (A),
Figure 445387DEST_PATH_IMAGE022
for the energy at the position of the AGC,
Figure 667421DEST_PATH_IMAGE023
in order to be the energy of the correlation,
Figure 752052DEST_PATH_IMAGE024
which is the position of the AGC symbol, symLen is the AGC symbol length,
Figure 714804DEST_PATH_IMAGE025
if the set synchronization judgment condition is met, the synchronization is successful; otherwise, discarding and re-entering the blind synchronization process.
6. The method of claim 1, wherein the method further comprises the steps of:
6.1 calculating channel coefficient, H;
6.2 calculating the total energy and the average energy in the frequency domain of the channel coefficient,
Figure 896387DEST_PATH_IMAGE026
，
Figure 164688DEST_PATH_IMAGE027
wherein, is the subcarrier length;
6.3 calculation
Figure 381354DEST_PATH_IMAGE029
The maximum value of (a) is,
Figure 346337DEST_PATH_IMAGE030
and the position is recorded,
Figure 847857DEST_PATH_IMAGE031
；
6.4 calculating the sign digit of the total energy and the average energy respectively,
Figure 907080DEST_PATH_IMAGE032
，
Figure 276881DEST_PATH_IMAGE033
and calculating the difference:
Figure 433056DEST_PATH_IMAGE034
；
6.5 the interference signal threshold value is set,
Figure 167794DEST_PATH_IMAGE035
if, if
Figure 776630DEST_PATH_IMAGE036
Then, there is an interference signal, and the interference position:
Figure 622226DEST_PATH_IMAGE037
the interference frequency points are:
Figure 632907DEST_PATH_IMAGE038
，
Figure 538546DEST_PATH_IMAGE039
for subcarrier spacing, an interference phase coefficient is established:
Figure 634678DEST_PATH_IMAGE040
，
Figure 94085DEST_PATH_IMAGE041
DL is time domain data length; if the condition is not satisfied, there is no interfering signal.
7. A reshaped tone interfering signal according to claim 1 characterized in that,
Figure 162535DEST_PATH_IMAGE042
。
8. the synchronous tracking phase receive signal processing according to claim 1,
Figure 301392DEST_PATH_IMAGE043
。
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CN112636831A (en) * 2020-12-03 2021-04-09 哈尔滨工业大学（深圳） Time synchronization method, system and storage medium based on DCO-OFDM visible light communication system
CN113965280A (en) * 2021-06-25 2022-01-21 西北工业大学 Adjacent channel interference suppression method in underwater multi-target communication
CN114268531A (en) * 2021-12-30 2022-04-01 深圳智微电子科技有限公司 Single tone interference detection and elimination method

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