CN114189420A - Satellite carrier synchronization method, device, equipment and medium based on compressed frame - Google Patents
Satellite carrier synchronization method, device, equipment and medium based on compressed frame Download PDFInfo
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- H04L27/26—Systems using multi-frequency codes
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Abstract
The application relates to a satellite carrier synchronization method, a satellite carrier synchronization device, a satellite carrier synchronization equipment and a satellite carrier synchronization medium based on compressed frames. The method comprises the following steps: the satellite receiving terminal extracts a compressed frame from the carrier input signal; performing data separation on the data in the compressed frame to obtain a short training sequence, a long training sequence and a data part; generating a frequency offset estimate value based on the short training sequence; generating a compensation coefficient based on the frequency offset estimate value, the short training sequence, and the long training sequence; and integrating based on the compensation coefficient and the long training sequence to complete carrier synchronization and generate a carrier output signal. The satellite carrier synchronization method and device based on the compressed frame, the electronic equipment and the computer readable medium can accurately and quickly perform synchronization processing on communication carrier signals of the satellite, and ensure the communication safety of the satellite.
Description
Technical Field
The present application relates to the field of satellite telemetry, and in particular, to a method and an apparatus for synchronizing satellite carriers based on compressed frames, an electronic device, and a computer-readable medium.
Background
Communication systems are an important part of performing satellite flight and various functions. The conventional satellite has a long data acquisition time period, and high-definition images and data signals can be acquired only after the task is finished. Due to the real-time performance of the control command system, high-speed data is required to meet the real-time performance of information transmission. The key for realizing remote control of the satellite is a data flow technology of broadband and big data. If data information can not be communicated and transmitted under the interference of enemies and normal instruction interaction can not be carried out, a command system of the satellite-based intelligent communication system can not operate the satellite, and the functional advantages of the satellite-based intelligent communication system can not be exerted.
The satellite launching and recovery control system, the main control system, the communication system and the satellite form a complete medium and long distance satellite system. The main control system is used for controlling the satellite to arrive at a designated place to complete certain tasks; the launching and recovering system can simultaneously control the rise and fall and communication of a plurality of satellites, is the core of the system and is a platform for completing various tasks. The communication system can transmit and recover various signals and is a bridge for connecting the control system and the satellite, so the development of the communication system directly influences the functional system of the whole satellite.
Therefore, a new method, apparatus, electronic device and computer readable medium for compressed frame based satellite carrier synchronization are needed.
The above information disclosed in this background section is only for enhancement of understanding of the background of the application and therefore it may contain information that does not constitute prior art that is already known to a person of ordinary skill in the art.
Disclosure of Invention
In view of this, the present application provides a method, an apparatus, an electronic device and a computer readable medium for synchronizing a satellite carrier based on a compressed frame, which can perform accurate and fast synchronization processing on a communication carrier signal of a satellite, thereby ensuring the security of satellite communication.
Other features and advantages of the present application will be apparent from the following detailed description, or may be learned by practice of the application.
According to an aspect of the present application, a method for synchronizing a satellite carrier based on a compressed frame is provided, the method comprising: the satellite receiving terminal extracts a compressed frame from the carrier input signal; performing data separation on the data in the compressed frame to obtain a short training sequence, a long training sequence and a data part; generating a frequency offset estimate value based on the short training sequence; generating a compensation coefficient based on the frequency offset estimate value, the short training sequence, and the long training sequence; and integrating based on the compensation coefficient and the long training sequence to complete carrier synchronization and generate a carrier output signal.
In an exemplary embodiment of the present application, a satellite receiving end extracts a compressed frame from a carrier input signal, including: a satellite sending end generates a satellite signal based on satellite data to be sent; an antenna of a satellite receiving end acquires a satellite signal in a wireless channel; signal processing the satellite signal to generate the carrier input signal; wherein the satellite data is used as a data portion of a compressed frame of a carrier input signal.
In an exemplary embodiment of the present application, data separation of data in the compressed frame to obtain a short training sequence, a long training sequence, and a data portion includes: extracting the short training sequence, the long training sequence and the data part from the compressed frame based on a preset frame structure of the compressed frame; the frame structure of the compressed frame comprises 10 short training sequences, 2 long training sequences, 1 first guard interval, 2 second guard intervals and a data part.
In an exemplary embodiment of the present application, further comprising: and acquiring the short training sequence, the symbol corresponding to the long training sequence and the data symbol in the carrier input signal based on a counter.
In an exemplary embodiment of the present application, generating a frequency offset estimate value based on the short training sequence comprises: dividing the short training sequence into a first short training sequence and a second short training sequence; generating an integer frequency offset estimator based on the first short training sequence; generating a decimal frequency offset estimator based on the first short training sequence and the second short training sequence; generating the frequency offset estimate value based on the integer frequency offset estimator and the fractional frequency offset estimator.
In an exemplary embodiment of the present application, dividing the short training sequence into a first short training sequence and a second short training sequence includes: taking the first 6 short training sequences in the short training sequences as the first short training sequence; and taking the last 4 short training sequences in the short training sequences as the second short training sequence.
In an exemplary embodiment of the present application, generating a compensation coefficient based on the frequency offset estimate value, the short training sequence, and the long training sequence comprises: determining a pilot frequency point based on a preset position; inserting the second short training sequence and the long training sequence in the pilot frequency point to generate pilot frequency information; interpolating the pilot frequency information to generate a channel estimation value; and generating a compensation coefficient based on the frequency offset estimation value and the channel estimation value.
In an exemplary embodiment of the present application, further comprising: the long training sequence is generated by the average of five long training sequences of the same frequency characteristics.
In an exemplary embodiment of the present application, integrating based on the compensation coefficient and the long training sequence to complete carrier synchronization and generate a carrier output signal includes: determining symbols and data symbols corresponding to the long training sequence; performing frequency offset compensation on the long training sequence based on the compensation coefficient, the symbol corresponding to the long training sequence and the data symbol; and integrating the data after the frequency offset compensation with the carrier input signal to complete carrier synchronization and generate a carrier output signal.
According to an aspect of the present application, a device for synchronizing satellite carriers based on compressed frames is provided, the device comprising: the extraction module is used for extracting a compressed frame from a carrier input signal at a satellite receiving end; the classification module is used for carrying out data separation on the data in the compressed frame to obtain a short training sequence, a long training sequence and a data part; an estimation module for generating a frequency offset estimation value based on the short training sequence; a compensation module for generating a compensation coefficient based on the frequency offset estimate, the short training sequence, and the long training sequence; and the output module is used for integrating the compensation coefficient and the long training sequence to complete carrier synchronization and generate a carrier output signal.
According to an aspect of the present application, an electronic device is provided, the electronic device including: one or more processors; storage means for storing one or more programs; when executed by one or more processors, cause the one or more processors to implement a method as above.
According to an aspect of the application, a computer-readable medium is proposed, on which a computer program is stored, which program, when being executed by a processor, carries out the method as above.
According to the satellite carrier synchronization method based on the compressed frame, the device, the electronic equipment and the computer readable medium, the compressed frame is extracted from the carrier input signal through the satellite receiving end; performing data separation on the data in the compressed frame to obtain a short training sequence, a long training sequence and a data part; generating a frequency offset estimate value based on the short training sequence; generating a compensation coefficient based on the frequency offset estimate value, the short training sequence, and the long training sequence; and based on the mode of integrating the compensation coefficient and the long training sequence to complete carrier synchronization and generate a carrier output signal, the communication carrier signal of the satellite can be accurately and quickly synchronized, and the satellite communication safety is ensured.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Drawings
The above and other objects, features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings. The drawings described below are only some embodiments of the present application, and other drawings may be derived from those drawings by those skilled in the art without inventive effort.
Fig. 1 is a flow chart illustrating a compressed frame based satellite carrier synchronization method according to an example embodiment.
Fig. 2 is a diagram illustrating a compressed frame based satellite carrier synchronization method according to an example embodiment.
Fig. 3 is a diagram illustrating a compressed frame based satellite carrier synchronization method according to an example embodiment.
Fig. 4 is a hardware implementation of a carrier frequency dependent synchronization scenario, shown in accordance with an example embodiment.
Fig. 5 is a diagram illustrating a compressed frame based satellite carrier synchronization method according to an example embodiment.
Fig. 6 is a diagram illustrating a compressed frame based satellite carrier synchronization method according to an example embodiment.
FIG. 7 is a time domain diagram illustrating real and imaginary parts of a short training sequence in a simulation according to an exemplary embodiment.
FIG. 8 is a time domain diagram illustrating real and imaginary parts of a long training sequence in a simulation according to an exemplary embodiment.
Fig. 9 is a graph illustrating a simulated bit error rate curve and a theoretical curve under gaussian white noise according to an exemplary embodiment.
Fig. 10 is a diagram illustrating simulation effects of a frequency offset estimation algorithm according to an exemplary embodiment.
Fig. 11 is a block diagram illustrating a compressed frame based satellite carrier synchronization apparatus according to another example embodiment.
FIG. 12 is a block diagram illustrating an electronic device in accordance with an example embodiment.
FIG. 13 is a block diagram illustrating a computer-readable medium in accordance with an example embodiment.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals denote the same or similar parts in the drawings, and thus, a repetitive description thereof will be omitted.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the subject matter of the present application can be practiced without one or more of the specific details, or with other methods, components, devices, steps, and so forth. In other instances, well-known methods, devices, implementations, or operations have not been shown or described in detail to avoid obscuring aspects of the application.
The block diagrams shown in the figures are functional entities only and do not necessarily correspond to physically separate entities. I.e. these functional entities may be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different networks and/or processor means and/or microcontroller means.
The flow charts shown in the drawings are merely illustrative and do not necessarily include all of the contents and operations/steps, nor do they necessarily have to be performed in the order described. For example, some operations/steps may be decomposed, and some operations/steps may be combined or partially combined, so that the actual execution sequence may be changed according to the actual situation.
It will be understood that, although the terms first, second, third, etc. may be used herein to describe various components, these components should not be limited by these terms. These terms are used to distinguish one element from another. Thus, a first component discussed below may be termed a second component without departing from the teachings of the present concepts. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
It will be appreciated by those skilled in the art that the drawings are merely schematic representations of exemplary embodiments, and that the blocks or processes shown in the drawings are not necessarily required to practice the present application and are, therefore, not intended to limit the scope of the present application.
Fig. 1 is a flow chart illustrating a compressed frame based satellite carrier synchronization method according to an example embodiment.
Fig. 1 is a flow chart illustrating a compressed frame based satellite carrier synchronization method according to an example embodiment. The compressed frame based satellite carrier synchronization method 10 includes at least steps S102 to S110.
As shown in fig. 1, in S102, the satellite receiving end extracts a compressed frame from the carrier input signal. For example, a satellite transmitting end generates a satellite signal based on satellite data to be transmitted; an antenna of a satellite receiving end acquires a satellite signal in a wireless channel; signal processing the satellite signal to generate the carrier input signal; wherein the satellite data is used as a data part of a compressed frame of a carrier input signal
In S104, data separation is performed on the data in the compressed frame to obtain a short training sequence, a long training sequence, and a data portion. The short training sequence, the long training sequence, and the data portion may be extracted from the compressed frame, for example, based on a preset frame structure of the compressed frame; the frame structure of the compressed frame comprises 10 short training sequences, 2 long training sequences, 1 first guard interval, 2 second guard intervals and a data part.
In the prior art, a frame structure of one OFDM (orthogonal frequency division multiplexing) data should include four kinds, i.e., a short training sequence, a long training sequence, a signal field part, and a data part. In the present application, frame data of a new compressed frame is extracted, in which the frame structure only contains short training sequences, long training sequences and data parts, i.e. no signal field is added.
As shown in fig. 2, wherein the short training sequence repeats 10 cycles in total, and each cycle is 16 in length, so the length is 160 in total; the long training sequence repeats two cycles, each cycle is 64 in length, and a cyclic prefix of length 32 is added before the first cycle; the data portion is 80 symbols long each, and consists of 16 cyclic prefixes and 64 data. The designed frame structure is shown in the figure.
In the frame structure shown in the figure, 1-10 represent ten short training sequences, LTS1 and LTS2 are two long training sequences, DATA is DATA to be transmitted, G1 and G are the long training sequence and cyclic prefix of the DATA, respectively, and the lengths are 32 and 16, respectively. The role of the parts in the frame structure is shown in table 1.
TABLE 1 Effect of various parts of the frame structure of an OFDM baseband system
In one embodiment, the short training sequence, the symbol corresponding to the long training sequence, and the data symbol in the carrier input signal may also be obtained based on a counter.
In S106, a frequency offset estimate value is generated based on the short training sequence. The short training sequence may be divided into a first short training sequence and a second short training sequence, for example; generating an integer frequency offset estimator based on the first short training sequence; generating a decimal frequency offset estimator based on the first short training sequence and the second short training sequence; generating the frequency offset estimate value based on the integer frequency offset estimator and the fractional frequency offset estimator.
More specifically, the first 6 short training sequences in the short training sequences may be used as the first short training sequence; and taking the last 4 short training sequences in the short training sequences as the second short training sequence.
Short training sequences for acquisition and framing, carrier-synchronized frequency offset estimation of long training sequences, then the frame header of the frame structure is six long sequences, the first five being identical, the same characteristics in the time domain of each sequence, so that there are always ten short sequences in the time domain. Since the ten peaks associated with the received sequence and the local sequence are arranged in descending and ascending order, the starting position of the data can be deduced based on the same concept as before. Since the channel and the frequency offset may affect the actual signal, that is, the actual system is greatly affected by the frequency offset, the probability of packet detection with an increased false alarm rate is reduced. The sequence combination using the SC algorithm is applied in combination with the Minn algorithm to further reduce the error. Although the Minn algorithm is used in the present application, the sequence used in the method is not obtained by the method, and the influence of the frequency offset on the system is reduced by using the corresponding five identical long sequences to take the average value of the sum of the five identical long sequences.
The use of the first five identical long sequences plus averaging makes the correlation peak more sharp, and also avoids the flat top state of the S & C method. Most importantly, it is also just a preliminary timing for frame detection, fine synchronization being applied using the locally stored sequence and the received sequence as correlation sequences. Since the timing accuracy is then integrated into the prior synchronization detection, the auto-correlation search method can more conveniently find the exact location of the search, and in this disclosure, fine synchronization is accomplished by using this algorithm.
This method is affected by too large a frequency offset. Therefore, the integer frequency offset can be estimated by using the detected frame, and then the frequency offset is corrected, so that the influence caused by the frequency offset can be weakened, and the timing accuracy, namely the accuracy in detection can be improved.
As shown in fig. 3, the data received by the receiving end includes a short training sequence, a long training sequence and a data portion, so that the short training sequence needs to be separated first to be used for frequency offset estimation, and therefore the first part of the module is data splitting to separate the first 5 short training sequences from others. The obtained 5 short training sequences are sent to a frequency offset estimation module, the estimated frequency offset is sent to a frequency offset compensation module to compensate the long training sequence and data, and finally, the compensation output and the cached short training are recombined into a complete data stream.
The frequency offset estimation module is divided into three parts of time delay correlation, correlation accumulation and deviation estimation, the key of hardware realization of the module is the realization of arctan, and because Altra corporation does not have a corresponding IP core to use, codes are written according to the arctan solving principle in the application, and the calculation of angles is realized.
Since the data and channel frequency domain responses are complex numbers, which are respectively set as a + jb and c + jd, and the compensated output is set as x + jy, then
The method in the prior art needs four multipliers to realize frequency offset estimation, and the method in the application can be realized by only three multipliers, so that the multiplier resources are saved.
In S108, a compensation coefficient is generated based on the frequency offset estimate value, the short training sequence, and the long training sequence. The pilot points may be determined, for example, based on preset locations; inserting the second short training sequence and the long training sequence in the pilot frequency point to generate pilot frequency information; interpolating the pilot frequency information to generate a channel estimation value; and generating a compensation coefficient based on the frequency offset estimation value and the channel estimation value.
More specifically, the long training sequence may be generated by an average of five long training sequences of the same frequency characteristics.
In S110, the long training sequence and the compensation coefficient are integrated to complete carrier synchronization and generate a carrier output signal. The symbols and data symbols corresponding to the long training sequence may be determined, for example; performing frequency offset compensation on the long training sequence based on the compensation coefficient, the symbol corresponding to the long training sequence and the data symbol; and integrating the data after the frequency offset compensation with the carrier input signal to complete carrier synchronization and generate a carrier output signal.
According to the satellite carrier synchronization method based on the compressed frames, the compressed frames are extracted from carrier input signals through a satellite receiving end; performing data separation on the data in the compressed frame to obtain a short training sequence, a long training sequence and a data part; generating a frequency offset estimate value based on the short training sequence; generating a compensation coefficient based on the frequency offset estimate value, the short training sequence, and the long training sequence; and based on the mode of integrating the compensation coefficient and the long training sequence to complete carrier synchronization and generate a carrier output signal, the communication carrier signal of the satellite can be accurately and quickly synchronized, and the satellite communication safety is ensured.
It should be clearly understood that this application describes how to make and use particular examples, but the principles of this application are not limited to any details of these examples. Rather, these principles can be applied to many other embodiments based on the teachings of the present disclosure.
In a specific embodiment, the specific steps of generating the compensation coefficients based on the frequency offset estimate, the short training sequence and the long training sequence may be as follows:
on the basis of a wireless communication system, a comb-shaped pilot frequency mechanism is used, only pilot frequency is used for completing auxiliary calculation in channel estimation, a part with the information is placed at a receiving part, and is converted into a frequency domain signal to be extracted, so that proper pilot frequency can be obtained, and the condition of obtaining an input signal can be recovered more accurately. In view of the previous analysis, comb pilots cannot be used continuously in the frequency domain, so a reasonable interpolation can have all the required information, and the relevant interpolation method and theoretical case are as follows.
Combining with interpolation relative channel estimation, selecting fixed position as pilot frequency point, inserting known signal sequence, using channel transmission to obtain pilot information, estimating the information, finding out ideal interpolation method according to the transmission number of pilot channel, and using interpolation relative function to obtain the required effective transfer function of non-pilot channel.
In one embodiment, the channel timing should be fast tracking. The algorithm has low complexity and is easier to implement. The pilot frequency presents time-frequency two-dimensional distribution in the system, so the calculation needs to be completed in two areas.
The implementation steps are as follows:
firstly, calculating the channel frequency response of the pilot frequency point by using an estimation algorithm:
secondly, according to the pilot frequency position and the determined structure degree, a related weight matrix W is obtained through calculation;
thirdly, frequency domain filtering, namely obtaining a channel response matrix related to the data subcarriers by using the weight matrix W and the channel estimation value of the pilot frequency position, wherein the channel response matrix is the only matrix related to the wavelet frequency domain:
fourthly, linear interpolation operation under the condition of time domain is completed, the pilot frequency of the adjacent OFDM symbols is used for completing channel estimation calculation on the intermediate sub-carrier, the pilot frequency carrier number is used, and the calculated channel estimation is filtered;
the channel estimation value generated by the data subcarrier is interpolated by using the adjacent pilot frequency points through the value obtained by the channel transfer function at the pilot frequency point estimation position, the frequency of the data subcarrier is recovered by using the information of the pilot frequency point,
under the condition that the channel estimation value is obtained, the channel information in the data splicing point is obtained in the same way as the interpolation process.
Generating a compensation coefficient of the system based on the frequency offset estimation value calculated by the training sequence and the channel estimation value obtained by the pilot frequency.
Such as the hardware implementation of the carrier frequency dependent synchronization case shown in fig. 4. The module mainly comprises a data stream part, a data buffer part, a carrier frequency offset estimation part, a frequency offset compensation part and a data output part. The operation process of the data in the module is as follows: firstly, judging the symbol and data symbol conditions respectively used by a short training sequence and a related long training sequence according to input data in a counter, and then completing different operations, which are data stream parts; the carrier frequency offset estimation part uses the obtained short training sequence to complete delay correlation addition and average operation so as to calculate a frequency offset estimation value; then, completing compensation coefficient operation based on the frequency offset estimation value, and then completing frequency offset compensation operation on related symbols and data symbols in the long training sequence by referring to the compensation coefficient; and finally, integrating the values obtained by the compensation operation with the values obtained by the original uncompensated operation, and outputting the expected data frame.
Data distribution module
The module performs an input operation of data and divides it into a short training sequence portion, a long training sequence portion and a data symbol portion. In the hardware implementation, a counter is used for counting, and when the count value is between 1 and 160, the count value is a short training symbol and enters a data cache module; when the counting value is between 1 and 80, the first 5 short symbols are sent to the carrier estimation module to complete the frequency offset estimation; when the count value exceeds 160, the long training sequence symbols and the data symbols which need the compensation operation are sent to the frequency offset compensation module.
Carrier frequency offset estimation submodule
This is the most important part of the whole module, and the estimation of field frequency deviation is completed according to the short training sequence symbol reference formula obtained from the data distribution part. As shown, it is composed of a delay correlation part, a correlation accumulation part, and a compensation calculation part.
Carrier frequency offset compensation submodule
The part is based on the calculation of frequency deviation compensation coefficient, and the frequency deviation compensation is needed
Compensation is performed.
In a hardware implementation, the module is divided into two parts: and calculating a compensation coefficient and compensating data. The compensation factor is delayed in view of the fact that it appears a little earlier than the compensation data, and the details thereof are as described in fig. 5.
For compensation factor calculation, when the frequency deviation is estimated
Is realized by complement counter
Taking the inverse, and using an accumulator to complete the phase angle operation
The compensation coefficient is
And
and (c). Compensation factors in the buffer when data is compensated
And outputting and using a complex multiplier to complete corresponding carrier frequency offset calculation.
Data association output submodule
The module is the last sub-module in the carrier synchronization module and is used for integrating and outputting long training sequences and data symbols, short training sequences and data symbols which are not subjected to frequency offset compensation. Because the short training symbols are directly sent to the data output module by the data distribution module, and the long training symbols and the data symbols are transmitted after compensation operation, in order to ensure that the short training symbols and the data symbols continuously complete the output operation, a shift register device is required to realize corresponding delay in hardware implementation.
The frequency offset estimation of the carrier is a very important part in the synchronization technology, and the frequency offset is also divided into an integer part and a decimal part. The fractional frequency offset can generate intersymbol interference, which is to say, the orthogonality of subcarriers is damaged, and ICI (inter-carrier interference) occurs; the frequency offset of the integer part can cause cyclic shift between data carriers of a receiver, although the orthogonality among the carriers cannot be destroyed. Statistically, the bit error rate of the system is random probability. Frequency offset estimation is often performed using Schmidl and Kim's approach and pilot-based estimation methods, and improvements are made in these methods, such as using only a special preamble. In general, estimating the frequency offset and synchronizing the timing are typically done together.
In a specific embodiment, the satellite carrier synchronization method described in the present application is simulated, and the windowed OFDM symbols are shown in figure 6,
in the context of figure 6 of the drawings,
the length of the guard interval is 2-4 times of the time delay spread root mean square value of the applied mobile environment channel under the general condition; beta is a roll-off coefficient, the larger the value of beta is, the faster the out-of-band radiated power is reduced, but the tolerance of the OFDM symbol to delay spread is also reduced, and the existence of the roll-off coefficient beta may bring ICI and ISI, so that the effective length of the guard interval is reduced from the original Tg to the current beta Ts.
The simulation parameter settings are shown in table 2:
table 2 simulation parameter settings
FIG. 7 is a time domain plot of the real and imaginary parts of a simulated medium-short training sequence, and FIG. 8 is a time domain plot of the real and imaginary parts of a simulated medium-long training sequence. Fig. 9 is a graph of simulated error rate and theoretical curve under gaussian white noise.
The bit error rate curve and the theoretical bit error rate curve (in the figure, EbN0 represents normalized signal-to-noise ratio) obtained by simulation in the Gaussian white noise channel can be seen to be basically consistent with the theoretical curve, the correctness of the noise component added in the design is verified, and the design of various parameters of the system in the additive Gaussian white noise channel is correct.
Fig. 10 is a diagram of simulation effect of frequency offset estimation algorithm performed by the method in the present application and the method in the prior art, as can be seen from the diagram, when the frequency offset is greater than 0.5, the estimation performance of the Moose algorithm is very poor, and the performance of the method based on the combination of the short training sequence and the coarse estimation and fine estimation is still very good, because the frequency offset exceeds the range that can be estimated by the cyclic prefix and the Moose algorithm when the frequency offset is greater than 0.5, and the performance is not good enough if only the short training sequence is used for estimation, so by using the method combining the coarse estimation and the fine estimation, the estimation performance can be ensured, and the estimation range can be increased, and the estimation range of the coarse estimation and the fine estimation is extended to (-2, 2) after simulation.
Those skilled in the art will appreciate that all or part of the steps implementing the above embodiments are implemented as computer programs executed by a CPU. When executed by the CPU, performs the functions defined by the methods provided herein. The program may be stored in a computer readable storage medium, which may be a read-only memory, a magnetic or optical disk, or the like.
Furthermore, it should be noted that the above-mentioned figures are only schematic illustrations of the processes involved in the method according to exemplary embodiments of the present application, and are not intended to be limiting. It will be readily understood that the processes shown in the above figures are not intended to indicate or limit the chronological order of the processes. In addition, it is also readily understood that these processes may be performed synchronously or asynchronously, e.g., in multiple modules.
The following are embodiments of the apparatus of the present application that may be used to perform embodiments of the method of the present application. For details which are not disclosed in the embodiments of the apparatus of the present application, reference is made to the embodiments of the method of the present application.
Fig. 11 is a block diagram illustrating a compressed frame based satellite carrier synchronization apparatus according to an example embodiment. As shown in fig. 11, the compressed frame based satellite carrier synchronization apparatus 110 includes: an extraction module 1102, a classification module 1104, an estimation module 1106, a compensation module 1108, and an output module 1110.
The extraction module 1102 is used for the satellite receiving end to extract the compressed frame from the carrier input signal;
the classification module 1104 is configured to perform data separation on the data in the compressed frame to obtain a short training sequence, a long training sequence, and a data portion;
an estimation module 1106 is configured to generate a frequency offset estimation value based on the short training sequence;
a compensation module 1108 is configured to generate a compensation coefficient based on the frequency offset estimate value, the short training sequence, and the long training sequence;
the output module 1110 is configured to perform integration based on the compensation coefficient and the long training sequence to complete carrier synchronization and generate a carrier output signal.
According to the satellite carrier synchronization device based on the compressed frames, the compressed frames are extracted from carrier input signals through a satellite receiving end; performing data separation on the data in the compressed frame to obtain a short training sequence, a long training sequence and a data part; generating a frequency offset estimate value based on the short training sequence; generating a compensation coefficient based on the frequency offset estimate value, the short training sequence, and the long training sequence; and based on the mode of integrating the compensation coefficient and the long training sequence to complete carrier synchronization and generate a carrier output signal, the communication carrier signal of the satellite can be accurately and quickly synchronized, and the satellite communication safety is ensured.
FIG. 12 is a block diagram illustrating an electronic device in accordance with an example embodiment.
An electronic device 1200 according to this embodiment of the present application is described below with reference to fig. 12. The electronic device 1200 shown in fig. 12 is only an example, and should not bring any limitation to the functions and the scope of use of the embodiments of the present application.
As shown in fig. 12, the electronic device 1200 is embodied in the form of a general purpose computing device. The components of the electronic device 1200 may include, but are not limited to: at least one processing unit 1210, at least one memory unit 1220, a bus 1230 connecting the various system components including the memory unit 1220 and the processing unit 1210, a display unit 1240, and the like.
Wherein the storage unit stores program code that can be executed by the processing unit 1210 such that the processing unit 1210 performs the steps according to various exemplary embodiments of the present application described in the present specification. For example, the processing unit 1210 may perform the steps as shown in fig. 2.
The storage unit 1220 may include a readable medium in the form of a volatile memory unit, such as a random access memory unit (RAM) 12201 and/or a cache memory unit 12202, and may further include a read only memory unit (ROM) 12203.
The memory unit 1220 may also include a program/utility 12204 having a set (at least one) of program modules 12205, such program modules 12205 including, but not limited to: an operating system, one or more application programs, other program modules, and program data, each of which, or some combination thereof, may comprise an implementation of a network environment.
The electronic device 1200 can also communicate with one or more external devices 1200' (e.g., keyboard, pointing device, bluetooth device, etc.) such that a user can communicate with devices with which the electronic device 1200 interacts, and/or any devices (e.g., router, modem, etc.) with which the electronic device 1200 can communicate with one or more other computing devices. Such communication may occur via input/output (I/O) interfaces 1250. Also, the electronic device 1200 may communicate with one or more networks (e.g., a Local Area Network (LAN), a Wide Area Network (WAN), and/or a public network such as the Internet) via the network adapter 1260. The network adapter 1260 may communicate with other modules of the electronic device 1200 via the bus 1230. It should be appreciated that although not shown, other hardware and/or software modules may be used in conjunction with the electronic device 1200, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems, among others.
Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein may be implemented by software, or by software in combination with necessary hardware. Therefore, as shown in fig. 13, the technical solution according to the embodiment of the present application may be embodied in the form of a software product, which may be stored in a non-volatile storage medium (which may be a CD-ROM, a usb disk, a removable hard disk, etc.) or on a network, and includes several instructions to enable a computing device (which may be a personal computer, a server, or a network device, etc.) to execute the above method according to the embodiment of the present application.
The software product may employ any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the foregoing. More specific examples (a non-exhaustive list) of the readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.
The computer readable storage medium may include a propagated data signal with readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated data signal may take many forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A readable storage medium may also be any readable medium that is not a readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a readable storage medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.
Program code for carrying out operations of the present application may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, as a stand-alone software package, partly on the user's computing device and partly on a remote computing device, or entirely on the remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user computing device through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computing device (e.g., through the internet using an internet service provider).
The computer readable medium carries one or more programs which, when executed by a device, cause the computer readable medium to perform the functions of: the satellite receiving terminal extracts a compressed frame from the carrier input signal; performing data separation on the data in the compressed frame to obtain a short training sequence, a long training sequence and a data part; generating a frequency offset estimate value based on the short training sequence; generating a compensation coefficient based on the frequency offset estimate value, the short training sequence, and the long training sequence; and integrating based on the compensation coefficient and the long training sequence to complete carrier synchronization and generate a carrier output signal.
Those skilled in the art will appreciate that the modules described above may be distributed in the apparatus according to the description of the embodiments, or may be modified accordingly in one or more apparatuses unique from the embodiments. The modules of the above embodiments may be combined into one module, or further split into multiple sub-modules.
Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein may be implemented by software, or by software in combination with necessary hardware. Therefore, the technical solution according to the embodiment of the present application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a usb disk, a removable hard disk, etc.) or on a network, and includes several instructions to enable a computing device (which can be a personal computer, a server, a mobile terminal, or a network device, etc.) to execute the method according to the embodiment of the present application.
Exemplary embodiments of the present application are specifically illustrated and described above. It is to be understood that the application is not limited to the details of construction, arrangement, or method of implementation described herein; on the contrary, the intention is to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims (12)
1. A method for synchronizing satellite carriers based on compressed frames is characterized by comprising the following steps:
the satellite receiving terminal extracts a compressed frame from the carrier input signal;
performing data separation on the data in the compressed frame to obtain a short training sequence, a long training sequence and a data part;
generating a frequency offset estimate value based on the short training sequence;
generating a compensation coefficient based on the frequency offset estimate value, the short training sequence, and the long training sequence;
integrating the compensation coefficients and the long training sequence to generate a carrier output signal.
2. The method of claim 1, wherein the satellite receiver extracts the compressed frame from the carrier input signal, comprising:
a satellite sending end generates a satellite signal based on satellite data to be sent;
an antenna of a satellite receiving end acquires a satellite signal in a wireless channel;
signal processing the satellite signal to generate the carrier input signal;
wherein the satellite data is used as a data portion of a compressed frame of a carrier input signal.
3. The method of claim 1, wherein data separating the data in the compressed frame to obtain a short training sequence, a long training sequence, a data portion, comprises:
extracting the short training sequence, the long training sequence and the data part from the compressed frame based on a preset frame structure of the compressed frame;
the frame structure of the compressed frame comprises 10 short training sequences, 2 long training sequences, 1 first guard interval, 2 second guard intervals and a data part.
4. The method of claim 3, further comprising:
and acquiring the short training sequence, the symbol corresponding to the long training sequence and the data symbol in the carrier input signal based on a counter.
5. The method of claim 1, wherein generating a frequency offset estimate value based on the short training sequence comprises:
dividing the short training sequence into a first short training sequence and a second short training sequence;
generating an integer frequency offset estimator based on the first short training sequence;
generating a decimal frequency offset estimator based on the first short training sequence and the second short training sequence;
generating the frequency offset estimate value based on the integer frequency offset estimator and the fractional frequency offset estimator.
6. The method of claim 5, wherein partitioning the short training sequence into a first short training sequence and a second short training sequence comprises:
taking the first 6 short training sequences in the short training sequences as the first short training sequence;
and taking the last 4 short training sequences in the short training sequences as the second short training sequence.
7. The method of claim 5, wherein generating compensation coefficients based on the frequency offset estimate values, the short training sequence, and the long training sequence comprises:
determining a pilot frequency point based on a preset position;
inserting the second short training sequence and the long training sequence in the pilot frequency point to generate pilot frequency information;
interpolating the pilot frequency information to generate a channel estimation value;
and generating a compensation coefficient based on the frequency offset estimation value and the channel estimation value.
8. The method of claim 7, further comprising:
the long training sequence is generated by the average of five long training sequences of the same frequency characteristics.
9. The method of claim 1, wherein integrating the compensation coefficients and the long training sequence to generate a carrier output signal comprises:
determining symbols and data symbols corresponding to the long training sequence;
performing frequency offset compensation on the long training sequence based on the compensation coefficient, the symbol corresponding to the long training sequence and the data symbol;
and integrating the data after frequency offset compensation with the carrier input signal to generate a carrier output signal.
10. A compressed frame based satellite carrier synchronization apparatus, comprising:
the extraction module is used for extracting a compressed frame from a carrier input signal at a satellite receiving end;
the classification module is used for carrying out data separation on the data in the compressed frame to obtain a short training sequence, a long training sequence and a data part;
an estimation module for generating a frequency offset estimation value based on the short training sequence;
a compensation module for generating a compensation coefficient based on the frequency offset estimate, the short training sequence, and the long training sequence;
and the output module is used for integrating the compensation coefficient and the long training sequence to generate a carrier output signal.
11. An electronic device, comprising:
one or more processors;
storage means for storing one or more programs;
when executed by the one or more processors, cause the one or more processors to implement the method of any one of claims 1-9.
12. A computer-readable medium, on which a computer program is stored, which, when being executed by a processor, carries out the method according to any one of claims 1-9.
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