CN113890591B - Carrier synchronization method and carrier synchronization demodulation device for low-orbit constellation system terminal - Google Patents
Carrier synchronization method and carrier synchronization demodulation device for low-orbit constellation system terminal Download PDFInfo
- Publication number
- CN113890591B CN113890591B CN202111215407.2A CN202111215407A CN113890591B CN 113890591 B CN113890591 B CN 113890591B CN 202111215407 A CN202111215407 A CN 202111215407A CN 113890591 B CN113890591 B CN 113890591B
- Authority
- CN
- China
- Prior art keywords
- module
- frequency
- timing
- value
- fine
- 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
Links
- 238000000034 method Methods 0.000 title claims abstract description 26
- 238000006243 chemical reaction Methods 0.000 claims abstract description 38
- 238000012545 processing Methods 0.000 claims abstract description 28
- 238000001914 filtration Methods 0.000 claims abstract description 6
- 230000001360 synchronised effect Effects 0.000 claims description 17
- 230000008569 process Effects 0.000 claims description 14
- 238000005070 sampling Methods 0.000 claims description 12
- 238000001228 spectrum Methods 0.000 claims description 12
- 238000004364 calculation method Methods 0.000 claims description 7
- 238000009825 accumulation Methods 0.000 claims description 3
- 238000013507 mapping Methods 0.000 claims description 3
- 238000000605 extraction Methods 0.000 claims description 2
- 230000009467 reduction Effects 0.000 claims description 2
- 230000001131 transforming effect Effects 0.000 claims description 2
- 238000004891 communication Methods 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 7
- 238000010295 mobile communication Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 3
- 239000013256 coordination polymer Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/1851—Systems using a satellite or space-based relay
- H04B7/18513—Transmission in a satellite or space-based system
-
- 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
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2657—Carrier synchronisation
- H04L27/2659—Coarse or integer frequency offset determination and 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
- H04L27/2657—Carrier synchronisation
- H04L27/266—Fine or fractional frequency offset determination and synchronisation
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Astronomy & Astrophysics (AREA)
- Aviation & Aerospace Engineering (AREA)
- General Physics & Mathematics (AREA)
- Synchronisation In Digital Transmission Systems (AREA)
Abstract
The invention discloses a carrier synchronization method and a carrier synchronization demodulation device for a low-orbit constellation system terminal, and belongs to the field of satellite communication. The carrier synchronization method comprises the following steps: the terminal carries out low-pass filtering and data downsampling on the downlink time domain signal, then carries out rapid capturing on a time domain primary synchronization signal PSS, and completes rough estimation of time domain signal timing and frequency; the terminal sends the coarse timing and frequency estimation information to a timing adjustment module and a digital down-conversion completion module to respectively finish timing adjustment and frequency compensation; performing FFT processing on the time domain data after coarse synchronization to finish the conversion from the time domain signal to the frequency domain signal; and sending the frequency domain data into a fine timing synchronization module to finish timing coarse synchronization estimation and timing fine synchronization estimation, compensating the frequency domain data by utilizing fine timing estimation information, performing despreading processing on the frequency domain data, and sending the despread reference signal into a frequency estimation module to finish carrier fine frequency estimation.
Description
Technical Field
The invention belongs to the technical field of satellite mobile communication, and particularly relates to a terminal carrier timing and frequency synchronization method under a low signal-to-noise ratio environment of a low-orbit satellite constellation system.
Background
In satellite mobile communication systems, a TDMA/FDMA scheme is commonly employed. The frame structure of the TDMA (Time Division Multiple Address, time division multiple access) system consists of ultra-high frames, super frames, multi-frames, frames and time slot numbers, and in the low-orbit constellation system, the relative position change between the satellite and the ground terminal quickly causes the characteristics of timing drift, large Doppler frequency offset and the like.
At present, a method for tracking timing and frequency in a low-orbit constellation is not described in detail in a low-orbit satellite scene by combining high-frequency spectrum-efficiency OFDM with a CDMA (code division multiple Access) technology system in the prior art, the existing low-orbit system is mainly concentrated on the research of CDMA (code division multiple Access) time domain spread spectrum and TDMA/FDMA (time division multiple Access) related transmission technologies, a ground mobile communication terminal related to the low-orbit constellation is not designed in a commercial miniaturization mode, most of the ground mobile communication terminals are experimental test equipment, and related timing estimation and frequency drift are designed by depending on a hardware clock scheme with high stability and precision.
Disclosure of Invention
In view of this, the invention provides a carrier synchronization method and a carrier synchronization demodulation device for a low-orbit constellation system terminal, the device and the method do not depend on hardware conditions, but adopt a software algorithm to complete timing and frequency tracking compensation of an OFDM combined frequency domain CDMA spread spectrum communication system scene under a weak signal of a low signal-to-noise ratio, and can effectively reduce the ground power spectral density of satellite signals.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a carrier synchronization method for a low-orbit constellation system terminal comprises the following steps:
(1) Setting a reference signal in OFDM as a fixed real value, performing CDMA spread spectrum processing, and mapping the spread reference signal to occupy the whole OFDM time domain symbol and all subcarrier positions of a frequency domain, wherein the data signal and the reference signal are subjected to scrambling and IFFT conversion processing after being overlapped in the frequency domain;
(2) FFT transforming the roughly synchronized time-domain downlink signal to obtain frequency-domain signals, and then finishing the anti-rotation factor e for each subcarrier signal in the frequency domain j2πkτ/N CompensationProcessing, wherein k=0, 1,2, …, N-1, τ is the search timing precompensation value, and the value range is [ -L.Ts, L.Ts]Each step of path of tau value is taken as Ts/M, wherein Ts is the time interval of sampling points, L and M are positive integers, and N is the number of subcarriers;
(3) Performing precompensation processing on each subcarrier by using each step tau value in the step (2), then performing despreading processing on the reference signal, despreading a reference symbol Q value for each N subcarriers, performing energy modular value operation on the Q value, and obtaining Q modular values corresponding to 2LM+1 tau value steps in total;
(4) Performing accumulation processing among a plurality of symbols by using 2LM+1 step Q modular values in the step (3), and finding out a maximum peak value from the accumulated value, wherein the abscissa corresponding to the peak value is a timing offset estimated value tau';
(5) Each subcarrier e is carried out on the frequency domain signal by using the tau' value in the step (4) j2πkτ’/N Timing precompensation, reducing the synchronous influence of timing error on spread spectrum signals, then carrying out fine frequency estimation on despread reference signal symbol data through FFT conversion, and obtaining a fine frequency offset estimation value f' by utilizing post-FFT amplitude peak value information;
(6) Utilizing the tau ' value in the step (4) to perform timing adjustment on the externally input baseband time domain signal, finishing the timing adjustment of the local counter after the tau ' value exceeds the integral multiple timing sampling point threshold value, and simultaneously updating tau ' to the residual decimal sampling point value; in addition, the fine frequency estimated value f' in the step (5) is utilized to carry out digital down conversion on the baseband time domain signal after timing adjustment, so as to complete frequency tracking compensation.
In addition, the invention also provides a carrier synchronous demodulation device of the low-rail constellation system terminal, which comprises a timing adjustment module, a digital down-conversion module, a digital filter module, a PSS synchronous module, an FFT module, a fine timing synchronous module, a fine frequency estimation module, a demodulation module and a decoding module; wherein:
the timing adjustment module receives the baseband time domain signal, counts sampling points, time slots, subframes and frames of the baseband time domain signal according to the coarse timing information output by the PSS synchronization module and the fine timing estimated value tau' output by the fine timing synchronization module, and sends the baseband time domain signal after timing adjustment to the digital down-conversion module;
the digital down-conversion module carries out frequency adjustment according to the coarse frequency estimated value output by the PSS synchronization module and the fine frequency estimated value f' output by the fine frequency estimated module, carries out digital frequency conversion compensation processing on the baseband time domain signal after timing adjustment, and sends the time domain baseband signal after frequency conversion to the digital filter module and the FFT module;
the digital filter module carries out filtering treatment on the signals sent by the digital down-conversion module, filters out signals outside the signal bandwidth, and sends the filtered time domain signals to the PSS synchronization module after the time domain signals are subjected to speed reduction and extraction;
the PSS synchronization module carries out time domain correlation capturing processing on the signals sent by the digital filter module, completes an initial synchronization process, outputs PSS synchronization information to the FFT module, sends coarse timing information to the timing adjustment module, and sends a coarse frequency estimated value to the digital down-conversion module;
the FFT module performs FFT conversion on the signal output by the digital down-conversion module by using PSS synchronous information, completes conversion from a time domain signal to a frequency domain signal, and sends the converted frequency domain signal to the fine timing synchronization module;
the fine timing synchronization module carries out fine timing related timing estimation calculation on the frequency domain signal, and sends the calculated fine timing estimation value tau' to the timing adjustment module to complete the fine timing synchronization adjustment process;
the fine frequency estimation module performs despreading processing on the frequency domain data of the reference signal after fine timing adjustment, then performs fine frequency estimation by utilizing FFT conversion, and sends a fine frequency estimation value f' to the digital down-conversion module to finish accurate frequency compensation;
the demodulation module performs despreading processing and channel estimation and equalization on the frequency domain data after the fine frequency estimation, and sends the demodulated data to the decoding module to complete channel decoding processing of the data.
The beneficial effects that adopt above-mentioned technical scheme to obtain lie in:
1. the invention is based on the OFDM combined frequency domain CDMA spread spectrum system in the satellite mobile communication system, can effectively complete the timing frequency estimation of satellite signals in weak signal and interference environment by utilizing the characteristics of high OFDM frequency spectrum efficiency and strong CDMA anti-interference capability, can effectively reduce the power spectrum density of the downlink signals of low orbit constellation satellites, and effectively improve the carrier synchronous estimation and tracking capability in large Doppler environment.
2. The invention is realized by adopting a mature software algorithm and system flow control without depending on hardware conditions, has higher technical maturity and is simple and reliable to realize.
Drawings
FIG. 1 is a functional block diagram of an embodiment of the present invention;
fig. 2 is a sub-carrier mapping diagram of a satellite mobile communication system per sub-frame according to an embodiment of the present invention;
FIG. 3 is a diagram showing the effect of the PSS synchronization module in the embodiment of the invention, and the accuracy of the horizontal axis coordinates is Ts;
FIG. 4 is a block diagram of an implementation of a fine timing synchronization module in an embodiment of the present invention;
FIG. 5 is a timing estimation effect diagram of the fine timing synchronization module in the embodiment of the invention, and the accuracy of the horizontal axis coordinate is Ts/8;
fig. 6 is a block diagram of a fine frequency estimation module according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
As shown in fig. 1, a carrier synchronous demodulation device for a low-rail constellation system terminal comprises a timing adjustment module, a digital down-conversion module, a digital filter, a PSS synchronous module, an FFT module, a fine timing synchronous module and a fine frequency estimation module. The terminal in the PSS synchronization module carries out low-pass filtering and data downsampling on the downlink time domain signal and then carries out rapid capture on the time domain PSS, and the rough estimation process of the time domain signal timing and frequency is completed; the fine timing synchronization module is responsible for large-range timing coarse synchronization estimation and small-range timing fine synchronization estimation under low signal-to-noise ratio, and utilizes the fine timing estimation information to complete compensation processing on frequency domain data, and meanwhile, despreads the frequency domain data, and sends despread reference signals to the frequency estimation module to complete carrier fine frequency estimation.
The carrier synchronization process in the device mainly comprises the following steps:
(1) The terminal carries out the rapid capturing of a time domain primary synchronization signal PSS after the downlink time domain signal is subjected to low-pass filtering and data downsampling, the rough estimation process of time domain signal timing and frequency is completed, the PSS time-frequency position and pilot frequency distribution are shown in figure 2, the PSS occupies the 2 nd symbol position of each time slot, the pilot frequency symbol and the data symbol occupy the rest symbol positions, and all the subcarrier bandwidth is occupied in frequency;
(2) The terminal sends the coarse timing and frequency estimation information to a timing adjustment module and a digital down-conversion completion module to respectively finish timing adjustment and frequency compensation;
(3) Performing FFT processing on the time domain data after coarse synchronization to finish the conversion from the time domain signal to the frequency domain signal;
(4) And sending the frequency domain data into a fine timing synchronization module to complete large-range timing coarse synchronization estimation and small-range timing fine synchronization estimation under low signal-to-noise ratio, compensating the frequency domain data by utilizing fine timing estimation information, simultaneously performing despreading processing on the frequency domain data, and sending the despread reference signal into a frequency estimation module to complete carrier fine frequency estimation.
The following is a more specific carrier synchronization procedure, which includes the following specific implementation steps:
(1) The terminal sends the downlink time domain signal to the PSS synchronization module after low-pass filtering and data downsampling, and the PSS synchronization module completes the time domain signal timing capturing and frequency rough estimation process, wherein the PSS capturing algorithm and the PSS realizing process are realized by referring to the ground universal standard, the PSS time domain sliding correlation peak searching effect diagram is shown in figure 3, and the abscissa with multiple corresponding peak positions is the rough synchronization position.
The principle of PSS detection is that the time-frequency characteristic (constant amplitude and zero autocorrelation) of the PSS sequence is utilized, firstly, the PSS time domain sequence is locally generated, all the PSS sequences are respectively subjected to sliding cross correlation with the received signal, the initial position of the PSS sequence is estimated, and the position corresponding to the maximum correlation peak value is judged to be the PSS coarse synchronization timing position. Under the condition that PSS timing offset estimation is completed, multiplying the received time domain PSS symbols by the local PSS sequence conjugate point of the time domain, and removing sequence information; then dividing the frequency offset into two parts, respectively summing, and finally estimating the frequency offset size:
wherein r is pss,i S for the ith received PSS sequence pss For locally generated PSS sequences, N is the OFDM symbol FFT sample length. Meanwhile, we can also jointly estimate C by a plurality of PSS signals acc ＝∑ l C (l) Thereby calculating normalized fractional frequency offset as:
wherein angle () is an angle calculation;
(2) The timing adjustment module carries out counter timing adjustment on the coarse timing information estimated by the PSS synchronization module, and the digital down-conversion module compensates the coarse frequency estimated by the PSS synchronization module;
(3) The FFT module performs FFT processing on the time domain data after coarse synchronization to finish the conversion process from the time domain signal to the frequency domain signal;
(4) The fine timing synchronization module will perform the anti-rotation factor e for each subcarrier signal r (k) in the frequency domain j2πkτ/N Compensation process, i.e. r (k, τ) =r (k) ·e j2πkτ/N Wherein k=0, 1,2, …, N-1, τ is the search timing precompensation value, the value range is [ -L.Ts, L.Ts]The value of tau per step is Ts/M, wherein Ts is the time interval of each sampling point, L and M are positive integers, N is the number of subcarriers, and the total number of tau per step is 2LM+1;
(5) The fine timing synchronization module counts τ values for each step size for each sub-carrierThe wave is pre-compensated and then the reference signal RS is de-spread, i.e. a reference symbol Q value is de-spread every N sub-carriers, i.eWherein c (k) corresponds to each subcarrier spreading code, and performs energy modular value operation on the Q values, so that 2LM+1 steps of radial Q modular values ||Q (tau) || can be obtained in total, and the calculation process of the specific fine timing synchronization module is shown in fig. 4, wherein the calculation process comprises FFT, anti-rotation, despreading, modular value calculation and the like;
(6) The fine timing synchronization module performs accumulation processing among a plurality of symbols on 2LM+1 step diameter I Q (tau) I values calculated on each OFDM symbol, namelyFinding out the maximum peak value from Q '(tau), wherein the position of the transverse axis corresponding to the maximum value is the value of the timing offset estimated value tau', and finally the distribution of the peak value calculation result is shown in figure 5, and the transverse axis unit is Ts/M;
(7) The fine frequency estimation module performs each subcarrier e on the frequency domain signal by using the timing estimation tau' value j2πkτ’/N Timing precompensation, i.e. r (k, τ')=r (k) ·e j2πkτ'/N Then, de-spreading the reference signal RS, and sending the de-spread Q (τ ') data to the FFT kernel to perform fine frequency estimation, and completing fine frequency offset estimation f' by using post-FFT amplitude peak information, where the specific process flow is shown in fig. 6, and the frequency is adopted for FFT estimation:
where fs is the frequency domain signal sampling rate,number of FFT subcarriers for frequency domain signal, CP LEN Is the OFDM symbol CP length; when the 2048-point FFT kernel is used for operation, the frequency estimation precision is FFT fs /2048。
(8) The timing adjustment module judges the fine timing estimation tau ' value, and when the tau ' value exceeds the integer multiple timing sampling point threshold value, the timing adjustment module can be started to finish the timing adjustment of the local counter, and meanwhile, tau ' is updated to the residual fractional multiple sampling point value; meanwhile, the digital down-conversion module carries out frequency tracking compensation on the fine frequency estimation f' value.
In a word, the method is suitable for a low-orbit constellation design scene adopting an OFDM combined frequency domain CDMA spread spectrum communication system, can effectively complete timing estimation and frequency tracking compensation of satellite signals under weak signals and interference environments, can effectively reduce the power spectrum density of satellite downlink signals of the low-orbit constellation under the OFDM combined frequency domain CDMA spread spectrum system, and can effectively improve carrier synchronous estimation and tracking capability under a large Doppler environment.
Claims (2)
1. The carrier synchronization method for the low-orbit constellation system terminal is characterized by comprising the following steps of:
(1) Setting a reference signal in OFDM as a fixed real value, performing CDMA spread spectrum processing, and mapping the spread reference signal to occupy the whole OFDM time domain symbol and all subcarrier positions of a frequency domain, wherein the data signal and the reference signal are subjected to scrambling and IFFT conversion processing after being overlapped in the frequency domain;
(2) FFT transforming the roughly synchronized time-domain downlink signal to obtain frequency-domain signals, and then finishing the anti-rotation factor e for each subcarrier signal in the frequency domain j2πkτ/N Compensation processing, wherein k=0, 1,2, …, N-1, τ is search timing precompensation value, and the value range is [ -L.Ts, L.Ts]Each step of path of tau value is taken as Ts/M, wherein Ts is the time interval of sampling points, L and M are positive integers, and N is the number of subcarriers;
(3) Performing precompensation processing on each subcarrier by using each step tau value in the step (2), then performing despreading processing on the reference signal, despreading a reference symbol Q value for each N subcarriers, performing energy modular value operation on the Q value, and obtaining Q modular values corresponding to 2LM+1 tau value steps in total;
(4) Performing accumulation processing among a plurality of symbols by using 2LM+1 step Q modular values in the step (3), and finding out a maximum peak value from the accumulated value, wherein the abscissa corresponding to the peak value is a timing offset estimated value tau';
(5) Each subcarrier e is carried out on the frequency domain signal by using the tau' value in the step (4) j2πkτ’/N Timing precompensation, reducing the synchronous influence of timing error on spread spectrum signals, then carrying out fine frequency estimation on despread reference signal symbol data through FFT conversion, and obtaining a fine frequency offset estimation value f' by utilizing post-FFT amplitude peak value information;
(6) Utilizing the tau ' value in the step (4) to perform timing adjustment on the externally input baseband time domain signal, finishing the timing adjustment of the local counter after the tau ' value exceeds the integral multiple timing sampling point threshold value, and simultaneously updating tau ' to the residual decimal sampling point value; in addition, the fine frequency estimated value f' in the step (5) is utilized to carry out digital down conversion on the baseband time domain signal after timing adjustment, so as to complete frequency tracking compensation.
2. The carrier synchronous demodulation device of the low-rail constellation system terminal is characterized by comprising a timing adjustment module, a digital down-conversion module, a digital filter module, a PSS synchronous module, an FFT module, a fine timing synchronous module, a fine frequency estimation module, a demodulation module and a decoding module; wherein:
the timing adjustment module receives the baseband time domain signal, counts sampling points, time slots, subframes and frames of the baseband time domain signal according to the coarse timing information output by the PSS synchronization module and the fine timing estimated value tau' output by the fine timing synchronization module, and sends the baseband time domain signal after timing adjustment to the digital down-conversion module;
the digital down-conversion module carries out frequency adjustment according to the coarse frequency estimated value output by the PSS synchronization module and the fine frequency estimated value f' output by the fine frequency estimated module, carries out digital frequency conversion compensation processing on the baseband time domain signal after timing adjustment, and sends the time domain baseband signal after frequency conversion to the digital filter module and the FFT module;
the digital filter module carries out filtering treatment on the signals sent by the digital down-conversion module, filters out signals outside the signal bandwidth, and sends the filtered time domain signals to the PSS synchronization module after the time domain signals are subjected to speed reduction and extraction;
the PSS synchronization module carries out time domain correlation capturing processing on the signals sent by the digital filter module, completes an initial synchronization process, outputs PSS synchronization information to the FFT module, sends coarse timing information to the timing adjustment module, and sends a coarse frequency estimated value to the digital down-conversion module;
the FFT module performs FFT conversion on the signal output by the digital down-conversion module by using PSS synchronous information, completes conversion from a time domain signal to a frequency domain signal, and sends the converted frequency domain signal to the fine timing synchronization module;
the fine timing synchronization module carries out fine timing related timing estimation calculation on the frequency domain signal, and sends the calculated fine timing estimation value tau' to the timing adjustment module to complete the fine timing synchronization adjustment process;
the fine frequency estimation module performs despreading processing on the frequency domain data of the reference signal after fine timing adjustment, then performs fine frequency estimation by utilizing FFT conversion, and sends a fine frequency estimation value f' to the digital down-conversion module to finish accurate frequency compensation;
the demodulation module performs despreading processing and channel estimation and equalization on the frequency domain data after the fine frequency estimation, and sends the demodulated data to the decoding module to complete channel decoding processing of the data.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111215407.2A CN113890591B (en) | 2021-10-19 | 2021-10-19 | Carrier synchronization method and carrier synchronization demodulation device for low-orbit constellation system terminal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111215407.2A CN113890591B (en) | 2021-10-19 | 2021-10-19 | Carrier synchronization method and carrier synchronization demodulation device for low-orbit constellation system terminal |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113890591A CN113890591A (en) | 2022-01-04 |
| CN113890591B true CN113890591B (en) | 2023-12-29 |
Family
ID=79003489
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111215407.2A Active CN113890591B (en) | 2021-10-19 | 2021-10-19 | Carrier synchronization method and carrier synchronization demodulation device for low-orbit constellation system terminal |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113890591B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114158128B (en) * | 2022-02-10 | 2022-05-17 | 北京理工大学 | Asymmetric dynamic time slot communication method and device for covert communication of synchronous orbit satellite |
| CN115988626B (en) * | 2022-12-20 | 2025-03-28 | 中国电子科技集团公司第五十四研究所 | A burst signal self-interference cancellation device based on FPGA |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101431498A (en) * | 2008-12-02 | 2009-05-13 | 清华大学 | Demodulation method and device for flexible sub-carrier modulation system |
| WO2013152561A1 (en) * | 2012-04-12 | 2013-10-17 | 中兴通讯股份有限公司 | Synchronization and equalization combined design method and device for microwave system |
| CN110266623A (en) * | 2019-06-05 | 2019-09-20 | 北京邮电大学 | A carrier synchronization method for low-orbit satellite communication system based on 5G |
| CN111683034A (en) * | 2020-06-09 | 2020-09-18 | 中国电子科技集团公司第五十四研究所 | OFDM-based large Doppler wireless communication time-frequency synchronization method |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010099808A1 (en) * | 2009-03-06 | 2010-09-10 | Telefonaktiebolaget Lm Ericsson (Publ) | A method of and equipment for compensating carrier frequency offset in an orthogonal frequency division multiplexing wireless radio transmission system |
| CN101924723B (en) * | 2009-06-09 | 2013-05-08 | 中兴通讯股份有限公司 | OFDM (Orthogonal Frequency Division Multiplexing) signal demodulation method and device |
-
2021
- 2021-10-19 CN CN202111215407.2A patent/CN113890591B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101431498A (en) * | 2008-12-02 | 2009-05-13 | 清华大学 | Demodulation method and device for flexible sub-carrier modulation system |
| WO2013152561A1 (en) * | 2012-04-12 | 2013-10-17 | 中兴通讯股份有限公司 | Synchronization and equalization combined design method and device for microwave system |
| CN110266623A (en) * | 2019-06-05 | 2019-09-20 | 北京邮电大学 | A carrier synchronization method for low-orbit satellite communication system based on 5G |
| CN111683034A (en) * | 2020-06-09 | 2020-09-18 | 中国电子科技集团公司第五十四研究所 | OFDM-based large Doppler wireless communication time-frequency synchronization method |
Non-Patent Citations (1)
| Title |
|---|
| 5G低轨卫星移动通信系统下行同步技术研究;周微;;信息通信(第09期);全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113890591A (en) | 2022-01-04 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111683034B (en) | OFDM-based large Doppler wireless communication time-frequency synchronization method | |
| US20110293040A1 (en) | Method and apparatus for signal acquisition in ofdm receivers | |
| CN107026810A (en) | The PN synchronization method of burst directly-enlarging system and its DS waveform that happens suddenly | |
| CN104280750B (en) | Long code capture systems based on partial matched filter fft algorithm and method | |
| CN113890591B (en) | Carrier synchronization method and carrier synchronization demodulation device for low-orbit constellation system terminal | |
| CN109088838B (en) | Pseudo code-Doppler fast capturing method of direct sequence spread spectrum DPSK signal under high dynamic condition | |
| US20010036221A1 (en) | Path search circuit dividing a received signal into a plurality of FFT windows to reduce arithmetic operation processes for cross-correlation coefficients | |
| US7499508B2 (en) | Method and apparatus for adjusting the gain of an if amplifier in a communication system | |
| CN101997804B (en) | Method and device for estimating synchronous timing deviation | |
| KR100681260B1 (en) | Speed Matched Channel Estimation Method Using Power Spectrum Based Speed Estimation and Demodulator of Mobile Communication Terminal Using the Same | |
| CN114285713B (en) | Low-orbit broadband satellite time frequency offset estimation method and system | |
| CN112511182B (en) | Satellite-borne measurement and control data transmission receiving device | |
| CN102480443B (en) | Carrier frequency offset estimation method and device for mobile communication system | |
| CN101330324B (en) | Method, apparatus and system for extracting synchronous indicating signal | |
| CN111446984A (en) | Single carrier phase rapid correction method and device | |
| CN112738000A (en) | PSS block cross-correlation detection method | |
| CN115296721B (en) | High-speed demodulation method, device and equipment suitable for low-orbit satellites | |
| CN112803968B (en) | Airborne measurement and control method for unmanned aerial vehicle | |
| CN112839001B (en) | Airborne measurement and control terminal of unmanned aerial vehicle | |
| CN112600784A (en) | Large frequency offset bit synchronization method based on quadratic differential correlation | |
| CN115865127B (en) | Parameter estimation and demodulation method for direct-spread signal | |
| CN114826324A (en) | Underwater mobile spread spectrum communication method based on frequency compression-energy receiver | |
| CN116073855B (en) | BL-DSSS signal code tracking method based on frequency domain matched filtering and time delay adjustment | |
| CN118573228B (en) | Acquisition algorithm and system for QV frequency band low-orbit satellite spread spectrum communication | |
| CN120017476B (en) | Signal synchronization method, device, equipment, medium and product |
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 |