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CN119276678B - Signal synchronization method and device based on OFDM system - Google Patents

Signal synchronization method and device based on OFDM system Download PDF

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Publication number
CN119276678B
CN119276678B CN202411787602.6A CN202411787602A CN119276678B CN 119276678 B CN119276678 B CN 119276678B CN 202411787602 A CN202411787602 A CN 202411787602A CN 119276678 B CN119276678 B CN 119276678B
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signal
preset
sampling point
phase difference
moment
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CN119276678A (en
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林雄鑫
朱忠益
龚子豪
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Suzhou Menhai Microelectronics Technology Co ltd
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Suzhou Menhai Microelectronics Technology Co ltd
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/26Systems using multi-frequency codes
    • H04L27/2601Multicarrier modulation systems
    • H04L27/2647Arrangements specific to the receiver only
    • H04L27/2655Synchronisation arrangements
    • H04L27/2668Details of algorithms
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/26Systems using multi-frequency codes
    • H04L27/2601Multicarrier modulation systems
    • H04L27/2647Arrangements specific to the receiver only
    • H04L27/2655Synchronisation arrangements
    • H04L27/2668Details of algorithms
    • H04L27/2681Details of algorithms characterised by constraints
    • H04L27/2688Resistance to perturbation, e.g. noise, interference or fading

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

The embodiment of the application relates to a signal synchronization method and a signal synchronization device based on an OFDM system, which are used for carrying out autocorrelation calculation on a received wireless signal through a preset time interval and a preset window length, judging whether a signal in the preset window length corresponding to a sampling point at a certain moment is an effective signal or not when the autocorrelation value corresponding to the sampling point at the moment is larger than a preset autocorrelation peak threshold value, further distinguishing false autocorrelation peaks caused by noise and real autocorrelation peaks caused by the effective signal, avoiding error synchronization phenomenon caused by noise and improving the accuracy and reliability of signal synchronization.

Description

Signal synchronization method and device based on OFDM system
Technical Field
The present invention relates to the field of power communications, and in particular, to a signal synchronization method and apparatus based on an OFDM system.
Background
In power carrier communication, a transmitting end of an Orthogonal Frequency Division Multiplexing (OFDM) system decomposes a transmission channel into a plurality of orthogonal sub-channels, converts a high-speed data signal to be transmitted into a parallel low-speed data stream, modulates the data stream onto sub-carriers of each orthogonal channel for transmission, and demodulates and separates a plurality of orthogonal signals superimposed for transmission in a certain manner at a receiving end. In OFDM communication systems, it is critical to ensure accuracy of time synchronization at the receiving end. Once the time synchronization is deviated, the orthogonality among subcarriers is destroyed, so that the interference among signals is increased, thereby affecting the correct demodulation of the signals, and meanwhile, the error receiving of the whole data packet is possibly caused, the situation of data packet loss is caused, and the stability and the reliability of communication are seriously affected.
The communication quality of the power carrier is greatly affected by the environment, especially wireless communication, the transmission environment is relatively complex, and the complexity of a signal path, channel variation and other factors increase the difficulty of data transmission. In wireless communications, the accuracy of time synchronization can be affected by various noise disturbances, especially some regular noise, such as sine wave noise. The regular noise has specific frequency, regular phase amplitude and the like, so that an autocorrelation peak is easy to appear in autocorrelation calculation, and the noise is obvious in idle time without effective signal transmission, thereby causing the occurrence of a missynchronization phenomenon. The missynchronization can cause phase and frequency deviation in the signal demodulation process, so that the receiving end cannot accurately restore the original data, and the communication quality is reduced. Even more serious, the missynchronization may also cause a chain reaction, increase the data processing amount, cause a series of errors in subsequent data processing, and finally affect the performance of the whole communication system. Therefore, how to improve the accuracy of synchronization and reduce the occurrence of the missynchronization phenomenon is a urgent problem to be solved.
Disclosure of Invention
In view of the above, in order to solve the problems in the background art, embodiments of the present application provide a signal frame synchronization method, a device, a readable storage medium, and an electronic apparatus.
In a first aspect, an embodiment of the present application provides a signal synchronization method based on an OFDM system, where the method includes:
receiving a wireless signal;
based on a preset delay interval and a preset window length, performing autocorrelation calculation on the wireless signal to obtain an autocorrelation value corresponding to a sampling point at each moment;
If the autocorrelation value corresponding to the sampling point at a certain moment is greater than a preset autocorrelation peak threshold, judging whether the signal in the preset window length corresponding to the sampling point at the moment is a valid signal or not;
If the signal in the preset window length corresponding to the time sampling point is an effective signal, the starting position of the signal frame in the wireless signal is obtained according to the time sampling point.
In a second aspect, an embodiment of the present application provides a signal synchronization apparatus based on an OFDM system, where the apparatus includes:
A receiving unit for receiving a wireless signal;
The self-correlation value calculation unit is used for carrying out self-correlation calculation on the wireless signal based on a preset delay interval and a preset window length to obtain a self-correlation value corresponding to a sampling point at each moment;
the judging unit is used for judging whether the signal in the preset window length corresponding to the sampling point at a certain moment is a valid signal or not if the autocorrelation value corresponding to the sampling point at the certain moment is larger than a preset autocorrelation peak threshold value;
and the starting position determining unit is used for obtaining the starting position of the signal frame in the wireless signal according to the time sampling point if the signal in the preset window length corresponding to the time sampling point is an effective signal.
In a third aspect, an embodiment of the present application provides a computer-readable storage medium storing instructions that, when executed by a processor of an electronic device, enable the electronic device to perform the OFDM system-based signal synchronization method provided in any one of the first aspects above.
In a fourth aspect, an embodiment of the present application provides an electronic device, including:
a processor;
a memory for storing computer-executable instructions;
the processor is configured to execute the computer-executable instructions to implement the OFDM system-based signal synchronization method according to any one of the first aspect.
According to the embodiment of the application, the received wireless signal is subjected to autocorrelation calculation through the preset time interval and the preset window length, and when the autocorrelation value corresponding to the sampling point at a certain moment is larger than the preset autocorrelation peak threshold value, whether the signal in the preset window length corresponding to the sampling point at the moment is an effective signal is judged, so that a false autocorrelation peak caused by noise and a true autocorrelation peak caused by the effective signal can be further distinguished, the error synchronization phenomenon caused by noise is avoided, and the accuracy and reliability of signal synchronization are improved.
Additional aspects and advantages of the application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the application.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:
Fig. 1 is a schematic flow chart of a signal synchronization method based on an OFDM system according to an embodiment of the present application;
FIG. 2 is a flowchart of a method for autocorrelation calculation according to one embodiment of the present application;
FIG. 3 is a flowchart illustrating a method for determining whether a time window signal is a valid signal according to an embodiment of the present application;
fig. 4 is a schematic diagram of a signal synchronization device based on an OFDM system according to an embodiment of the present application;
Fig. 5 is a schematic structural diagram of an electronic device according to an embodiment of the present application.
Detailed Description
In order to make the technical scheme and the beneficial effects of the invention more obvious and understandable, the following detailed description is given by way of example. In this disclosure, it should be understood that terms such as "comprises" or "comprising," etc., are intended to indicate the presence of features, numbers, steps, acts, portions, or combinations thereof disclosed in this specification, and are not intended to exclude the possibility that one or more other features, numbers, steps, acts, portions, or combinations thereof are present or added.
The present disclosure will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
The wireless signal synchronization method based on the OFDM system is used for a high-speed power line carrier communication (HPLC) - (high-speed wireless communication) HRF dual-mode system, so that the synchronization accuracy and reliability of the HRF signals are improved. It should be noted that, the HPLC-HRF dual-mode system uses the power line and the space as the transmission medium, and forms the complementary advantage between the wired and wireless. In the HPCL-HRF dual-mode system, the HRF signal synchronization is realized through short training Sequence (STF) autocorrelation calculation, but due to correlation characteristics such as interference, multipath, attenuation and the like in a power grid environment, the STF autocorrelation peak detection is easy to generate false detection, so that the occurrence of false synchronization is caused.
Fig. 1 is a flowchart illustrating a signal synchronization method based on an OFDM system according to an embodiment of the present application. As shown in fig. 1, the synchronization method provided in this embodiment includes the following steps:
S1, receiving a wireless signal.
Specifically, the wireless signal includes a valid signal and a noise signal. The effective signal is an HRF signal sent by a sending end, the HRF signal can be formed by one or more signal frames, each signal frame is formed by a preamble, a physical frame header control word (SIG), a physical frame header (PHR) and a physical layer service unit (PSDU), wherein the preamble comprises an STF and a long training sequence (LTF), the STF is used for signal frame synchronization and coarse frequency synchronization, and the LTF is used for fine frequency synchronization and signal estimation. The STF has a specific sequence structure, is repeated or periodic in time domain, so that the STF can be identified through autocorrelation calculation, and particularly, when a certain part of a signal is similar to other parts of the signal, an autocorrelation peak can be obtained through autocorrelation calculation, and once the autocorrelation peak is found, the starting position of a signal frame can be determined. It should be noted that, there is a frame interval between adjacent signal frames, the signal in the frame interval is not an effective signal, and the length of the frame interval is not fixed, but the transmitting end varies according to the actual communication situation.
S2, based on a preset delay interval and a preset window length, performing autocorrelation calculation on the wireless signal to obtain an autocorrelation value corresponding to each sampling point at each moment.
The preset delay interval and the preset window length are set according to the length of the STF and the data format of the STF in the communication protocol. Optionally, the preset delay interval is equal to the number of sampling point intervals of the repeated data segments in the STF, and the preset window length is equal to the length of the STF. For example, if each STF is made up of 8 sets of repeated data, each set of data having 10 samples, the preset delay interval is 10 samples, and the preset window length is 80 samples. It should be noted that each data frame may include one or more STFs, and is not limited in this disclosure, particularly with respect to communication protocols.
Fig. 2 is a flowchart of a method for autocorrelation calculation according to an embodiment of the present application. As shown in fig. 2, as an alternative embodiment, S2 includes:
S201, obtaining a first signal based on a preset window length and a sampling point at the current moment.
The first signal is a signal in a preset window length corresponding to a sampling point at the current moment. Specifically, sampling points are sequentially taken forward from the sampling point at the current moment until the length between the last sampling point and the sampling point at the current moment is equal to the length of a preset window.
S202, acquiring an autocorrelation calculation sequence corresponding to a sampling point at the current moment from a first signal according to a preset sampling rule based on a preset delay interval.
The preset sampling rule is that sampling points with preset delay intervals are sequentially selected forwards from the sampling point at the current moment. Specifically, for example, a certain first signal is { k1, k2, k3...once. K16}, where k16 is the current time instant sample point, the preset delay interval is 4 sampling intervals, and the autocorrelation calculation sequence corresponding to the sampling point at the current moment is { k16, k12, k8, k4}.
S203, according to the autocorrelation calculation sequence corresponding to the sampling point at the current moment, calculating an autocorrelation value corresponding to the sampling point at the current moment.
Optionally, the autocorrelation value corresponding to the sampling point at the current time is calculated by the following formula:
Wherein, Represents the autocorrelation value of the sampling point at the current t moment, n represents the nth sampling point corresponding to the current t moment,And k is a constant and is determined according to the number of the STF repeated data in the communication protocol.
Compared with power line carrier communication, the wireless carrier communication transmission environment is relatively complex, the complexity of signals, channel variation and other factors increase the difficulty of data transmission, and the position of the signals can be easily and rapidly determined through an autocorrelation algorithm based on the repeatability of data in the STF. Furthermore, the conventional autocorrelation method performs autocorrelation calculation based on continuous signal sampling points, which is large in calculation amount and time-consuming, and is easy to cause calculation errors due to noise interference. According to the embodiment of the application, the autocorrelation calculation is performed by sampling through the preset time window and the preset delay interval based on the regularity of the STF data of the transmitted signal, so that the calculated amount is reduced, the repeated data in the signal can be more accurately identified, and the accuracy and reliability of synchronization are improved.
And S3, if the autocorrelation value corresponding to the sampling point at a certain moment is larger than a preset autocorrelation peak threshold value, judging whether the signal in the preset window length corresponding to the sampling point at the moment is a valid signal.
Specifically, if the autocorrelation value corresponding to a sampling point at a certain moment is greater than a preset autocorrelation peak threshold, the sampling point at the current moment is indicated to be an autocorrelation peak, and correspondingly, the starting position of the signal frame can be obtained according to the sampling point at the current moment. In the prior art, the noise signal can seriously affect the identification of the autocorrelation peak in the effective signal, especially when some periodic regular noise such as sine wave exists, the autocorrelation peak can also exist in the noise signal, thereby causing the occurrence of error synchronization and seriously affecting the accuracy of signal synchronization. For example, in OFDM systems, the transmitting end typically requires a local oscillator to generate a carrier signal that is modulated with the data signal to be transmitted and then transmitted into the power line. However, due to design reasons or environmental factors of the system, such as insufficient physical isolation of the local oscillator, circuit design defects, or external electromagnetic interference, signals of the local oscillator may leak to other parts of the system, especially to an output end of the transmitting end, so that regular sine wave noise is generated at the transmitting end, and the sine wave noise, similar to the STF in the preamble, has a specific structure and a fixed length, also presents a periodic waveform in a time domain and is also a plurality of discrete frequency components in a frequency domain, so that an autocorrelation value is easily greater than an autocorrelation threshold when performing autocorrelation calculation, that is, the periodic noise is also easily generated into an autocorrelation peak. In the prior art, due to the existence of periodic noise, the starting position of a signal frame can be determined to possibly cause a missynchronization phenomenon only by relying on the occurrence of an autocorrelation peak, and in the embodiment of the application, by judging whether a time window signal corresponding to the autocorrelation peak is an effective signal or not, the false autocorrelation peak caused by the periodic noise and the true autocorrelation peak caused by the effective signal can be more accurately distinguished, thereby avoiding the missynchronization phenomenon caused by the periodic noise and improving the accuracy and reliability of signal synchronization.
It should be noted that, if sine wave noise exists in the idle stage without signal transmission, the false identification of the sine wave in the noise as an effective signal may cause subsequent demodulation errors, and may require additional computing resources to perform error detection and correction, thereby reducing the overall efficiency of the system, and in extreme cases, the false synchronization is continuously present and cannot be solved, which may cause the system to fail to work normally. If sine wave noise exists in the signal transmission stage, since there is a frame interval between signal frames, useless signals between frame intervals are easily identified as effective signals, so that error data is introduced in the next demodulation processing, and the communication performance of the system is affected.
FIG. 3 is a flowchart illustrating a method for determining whether a time window signal is a valid signal according to an embodiment of the present application. As shown in fig. 3, as an alternative specific embodiment, determining whether a signal within a preset window length corresponding to a sampling point at the time is a valid signal includes:
s301, calculating phase differences of adjacent sampling points in signals within a preset window length, and obtaining a first phase difference sequence.
Specifically, the time window signal corresponding to the autocorrelation peak includes information such as a count value, an amplitude, a phase, and the like of each sampling point, where the phase of the sampling point in the time window signal is......Where n represents the number of sampling points in the time window signal,Indicating the phase of the nth sample point. Specifically, the phase difference between adjacent sampling points is calculated by the following formula:
Wherein, Representing the phase difference value of the n-1 th adjacent point,Indicating the phase of the nth sample point,Indicating the phase of the n-1 th sample point.
In the embodiment of the application, the first phase difference sequence obtained according to the time window signal corresponding to the autocorrelation peak is....... For sine wave noise, the time interval between each sampling point is the same, and the phase difference between adjacent sampling points is ideally a fixed value, namely===......But the specific value is related to the sampling interval. The ideal sine wave signal is a periodic waveform, the change in each period is consistent, when sampling is carried out at fixed time intervals, the sine wave phase is increased by fixed increment along with the time sampling period, the increment is determined by the signal frequency and the sampling period, the higher the frequency is, the faster the phase change is, the shorter the sampling period is, the more obvious the phase difference between adjacent points is, but the phase difference between the adjacent points is always fixed regardless of the change.
S302, calculating the difference value of adjacent points in the first phase difference sequence to obtain a second phase difference sequence.
Specifically, the difference between adjacent points in the first phase difference sequence is calculated by the following formula:
Wherein, Representing the difference between the n-2 th adjacent points in the first phase difference sequence. Correspondingly, the second phase difference sequence is....... The values in the second phase difference sequence are zero for the ideal sine wave noise.
S303, accumulating the values in the second phase difference sequence to obtain an accumulated phase difference value.
Specifically, the accumulated phase difference value is calculated by the following formula:
Wherein, Representing the accumulated phase difference value. For ideal sine wave noise, its cumulative phase difference value is zero. In the real communication, when no idle phase of effective signal transmission exists, the noise comprises sine wave noise and other noise, the accumulated phase difference value changes within a certain threshold value range, the accumulated phase difference value is relatively smaller, when the phase of effective signal transmission exists, the time window signal comprises effective signal, sine wave noise and other noise, the accumulated phase difference value is mainly related to the sine wave noise and the effective signal, and the accumulated phase difference value is the result of superposition of the sine wave noise and the effective signal, and the relative value is larger. It should be noted that, the idle phase where no active signal transmission exists in the embodiment of the present application further includes an interval phase between signal frames in the active signal transmission process, that is, further includes a frame interval phase between signal frames.
S304, comparing the accumulated phase difference value with a preset effective threshold value, and judging whether the signal in the preset window length corresponding to the sampling point at the moment is an effective signal or not according to the comparison result.
Specifically, S304 includes if the absolute value of the accumulated phase difference value is smaller than a preset valid threshold, the signal in the preset window length corresponding to the sampling point at the moment is not a valid signal, and if the absolute value of the accumulated phase difference value is larger than the preset valid threshold, the signal in the preset window length corresponding to the sampling point at the moment is a valid signal.
In the embodiment of the application, by comparing the accumulated phase difference value corresponding to the time window signal with the preset effective threshold value, whether the time window length corresponding to the sampling point is an effective signal or not can be judged, thereby effectively avoiding the problem of error synchronization caused by sine wave noise and improving the synchronization precision and reliability of an OFDM system. It should be noted that, the preset effective threshold may be set according to an actual communication situation.
As an alternative embodiment, the preset valid threshold is obtained according to the local reference sequence and the preset reference coefficient. Specifically, the preset effective threshold is calculated according to the following formula:
β=k’*λ
Where β represents a preset effective threshold, k' represents a local accumulated phase difference value, and λ represents a preset reference coefficient. Lambda is smaller than 1, and the specific value is set according to the actual communication condition.
Optionally, calculating a local accumulated phase difference value according to the local reference sequence specifically includes calculating a phase difference of adjacent sampling points in the local reference sequence to obtain a first local phase difference sequence, calculating a difference of adjacent points in the first local phase difference sequence to obtain a second local phase difference sequence, and accumulating values in the second local phase difference sequence to obtain a local accumulated phase difference value. It should be noted that the local reference sequence is data pre-stored in the receiving end, and specifically, the local reference sequence is STF in the preamble.
In the embodiment of the application, although the local reference sequence has certain regularity, the phase difference value of the adjacent sampling points is not a fixed value, so that the accumulated phase difference value calculated by sine wave noise and the local accumulated phase difference value calculated by the local reference sequence are obviously different, and the preset effective threshold value is obtained by utilizing the local accumulated phase difference value and the preset reference coefficient, thereby effectively judging whether the corresponding time window signal is an effective signal or a noise signal, and improving the accuracy and reliability of judgment.
And S4, if the signal in the preset window length corresponding to the time sampling point is an effective signal, acquiring the starting position of a signal frame in the wireless signal according to the time sampling point.
In an embodiment of the present application, the starting position of the frame signal in the received signal is determined by the autocorrelation peak, and then the received signal can be subjected to subsequent demodulation processing according to the starting position of the frame signal.
In the embodiment of the application, whether the signal in the preset window length corresponding to the autocorrelation peak is an effective signal or not is judged, so that the false autocorrelation peak caused by periodic noise and the real autocorrelation peak caused by the effective signal can be accurately distinguished, the error synchronization phenomenon caused by the periodic noise is avoided, and the accuracy and reliability of signal synchronization are improved.
The signal frame synchronization method provided by the embodiment of the application can be particularly applied to electronic equipment, and the electronic equipment can be equipment such as a terminal or a server.
It should be understood that, although the steps in the flowcharts of fig. 1-3 are shown in order as indicated by the arrows, these steps are not necessarily performed in order as indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in fig. 1-3 may include multiple steps or stages that are not necessarily performed at the same time, but may be performed at different times, nor do the order in which the steps or stages are performed necessarily performed in sequence, but may be performed alternately or alternately with at least a portion of the steps or stages in other steps or other steps.
Fig. 4 is a schematic diagram of a signal synchronization device based on an OFDM system according to an embodiment of the application. As shown in fig. 4, the synchronization apparatus includes:
A receiving unit 100 for receiving a wireless signal;
An autocorrelation value calculation unit 200, configured to perform autocorrelation calculation on the wireless signal based on a preset delay interval and a preset window length, to obtain an autocorrelation value corresponding to a sampling point at each time;
The judging unit 300 is configured to judge whether a signal in a preset window length corresponding to a sampling point at a certain time is a valid signal if an autocorrelation value corresponding to the sampling point at the certain time is greater than a preset autocorrelation peak threshold;
the starting position determining unit 400 is configured to obtain a starting position of a signal frame in the wireless signal according to the time sampling point if the signal in the preset window length corresponding to the time sampling point is a valid signal.
Optionally, the judging unit 300 includes:
the first phase difference sequence calculation unit is used for calculating the phase difference of adjacent sampling points in the signal within the preset window length to obtain a first phase difference sequence;
the second phase difference sequence calculation unit is used for calculating the difference value of adjacent points in the first phase difference sequence to obtain a second phase difference sequence;
the accumulated phase difference value calculation unit is used for accumulating the values in the second phase difference sequence to obtain an accumulated phase difference value;
And the comparison judging unit is used for comparing the accumulated phase difference value with a preset effective threshold value, and judging whether the signal in the preset window length corresponding to the sampling point at the moment is an effective signal or not according to the comparison result.
Optionally, judging whether the signal in the preset window length corresponding to the sampling point at the moment is a valid signal according to the comparison result includes:
If the absolute value of the accumulated phase difference value is smaller than a preset effective threshold value, the signal in the preset window length corresponding to the sampling point at the moment is not an effective signal;
If the absolute value of the accumulated phase difference value is larger than the preset effective threshold value, the signal in the preset window length corresponding to the sampling point at the moment is an effective signal.
Optionally, the preset effective threshold is calculated according to the local reference sequence and the preset reference coefficient.
Optionally, the autocorrelation value calculation unit 200 includes:
The first signal acquisition unit is used for acquiring a first signal based on a preset window length and a current time sampling point, wherein the first signal is a signal in the preset window length corresponding to the current time sampling point;
the self-correlation sequence sampling unit is used for acquiring a self-correlation calculation sequence corresponding to a sampling point at the current moment from the first signal according to a preset sampling rule based on a preset delay interval;
and the sampling point autocorrelation calculating unit is used for calculating an autocorrelation value corresponding to the sampling point at the current moment according to the autocorrelation calculating sequence corresponding to the sampling point at the current moment.
Optionally, the autocorrelation value corresponding to the sampling point at the current time is calculated by the following formula:
Wherein, Represents the autocorrelation value of the sampling point at the current t moment, n represents the nth sampling point corresponding to the current t moment,And k is a constant and is determined according to the number of the STF repeated data in the communication protocol.
The embodiment of the application also provides a computer readable storage medium. The computer readable storage medium stores instructions that, when executed by a processor of an electronic device, enable the electronic device to perform the steps in the OFDM system based signal synchronization method of any of the embodiments described above.
Embodiments of the present application may be a system, method, and/or computer program product. The computer program product may include a computer readable storage medium having computer readable program instructions embodied thereon for causing a processor to implement aspects of the present application. In some embodiments, aspects of the present application are implemented by personalizing electronic circuitry, such as programmable logic circuitry, field Programmable Gate Arrays (FPGAs), or Programmable Logic Arrays (PLAs), with state information for computer readable program instructions, which can execute the computer readable program instructions.
A computer readable storage medium 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 computer readable storage medium is a tangible device that can hold and store instructions for use by an instruction execution device. The readable storage medium may include, for example, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples of a readable storage medium (a non-exhaustive list) include a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a Static Random Access Memory (SRAM), a portable compact disc read-only memory (CD-ROM), a Digital Versatile Disc (DVD), a memory stick, a floppy disk, a mechanical encoding device, punch cards or in-groove protrusion structures such as those having instructions stored thereon, and any suitable combination of the foregoing.
Various aspects of the present application are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer-readable program instructions.
The embodiment of the application also provides electronic equipment. Fig. 5 is a schematic structural diagram of an electronic device according to an embodiment of the present application. As shown in fig. 5, the electronic device 500 includes one or more processors 501 and a memory 502, where the memory 502 stores computer executable instructions, and the processor 501 is configured to execute the computer executable instructions to implement steps in the OFDM system based signal synchronization method according to any of the embodiments described above.
The processor 501 may be a Central Processing Unit (CPU) or other form of processing unit having data processing and/or instruction execution capabilities and may control other components in the electronic device to perform desired functions.
Memory 502 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and/or non-volatile memory. Volatile memory can include, for example, random Access Memory (RAM) and/or cache memory (cache) and the like. The non-volatile memory may include, for example, read Only Memory (ROM), hard disk, flash memory, and the like. One or more computer program instructions may be stored on a computer readable storage medium and the processor 501 may execute the program instructions to implement the steps in the text recognition method and/or other desired functions of the various embodiments of the present application above.
In one example, electronic device 500 may also include input devices and output devices that are interconnected by a bus system and/or other forms of connection mechanisms (not shown).
In addition, the input device may also include, for example, a keyboard, a mouse, a microphone, and the like. The output means may output various information to the outside, and may include, for example, a display, a speaker, a printer, and a communication network and a remote output device connected thereto, and the like.
Of course, only a part of the components of the electronic device 500 relevant to the present application are shown in fig. 5 for simplicity, and components such as a bus, an input device/output interface, and the like are omitted. In addition, the electronic device 500 may include any other suitable components depending on the particular application.
It should be noted that the signal synchronization method embodiment based on the OFDM system, the signal synchronization device embodiment based on the OFDM system, the computer readable storage medium embodiment and the electronic device embodiment provided by the embodiment of the present application belong to the same concept, and all technical features in the technical solutions described in the embodiments may be arbitrarily combined without collision.
It should be understood that the above examples are illustrative and are not intended to encompass all possible implementations encompassed by the claims. Various modifications and changes may be made in the above embodiments without departing from the scope of the disclosure. Likewise, the individual features of the above embodiments can also be combined arbitrarily to form further embodiments of the invention which may not be explicitly described. Therefore, the above examples merely represent several embodiments of the present invention and do not limit the scope of protection of the patent of the present invention.

Claims (10)

1.一种基于OFDM系统的信号同步方法,其特征在于,所述方法包括:1. A signal synchronization method based on an OFDM system, characterized in that the method comprises: 接收无线信号;Receive wireless signals; 基于预设延迟间隔和预设窗口长度,对所述无线信号进行自相关计算,获得每一时刻采样点对应的自相关值;其中,预设窗口长度等于短训练序列(STF)的长度;预设延迟间隔等于STF中重复数据段的采样点间隔数;Based on a preset delay interval and a preset window length, an autocorrelation calculation is performed on the wireless signal to obtain an autocorrelation value corresponding to a sampling point at each moment; wherein the preset window length is equal to the length of a short training sequence (STF); and the preset delay interval is equal to the number of sampling point intervals of a repeated data segment in the STF; 若某一时刻采样点对应的自相关值大于预设自相关峰阈值,则判断该时刻采样点对应的预设窗口长度内的信号是否是有效信号;If the autocorrelation value corresponding to a sampling point at a certain moment is greater than a preset autocorrelation peak threshold, it is determined whether the signal within the preset window length corresponding to the sampling point at that moment is a valid signal; 若该时刻采样点对应的预设窗口长度内的信号是有效信号,则根据该时刻采样点获得所述无线信号中信号帧的起始位置;If the signal within the preset window length corresponding to the sampling point at the moment is a valid signal, then obtaining the starting position of the signal frame in the wireless signal according to the sampling point at the moment; 其中,通过以下公式计算每一时刻采样点对应的自相关值:Among them, the autocorrelation value corresponding to each sampling point at each moment is calculated by the following formula: , 其中,表示当前t时刻采样点的自相关值,n表示当前t时刻对应的第n个采样点,表示第n个采样点的幅值,m表示预设延迟间隔;k为常数,根据通信协议中STF重复数据的数量确定;in, represents the autocorrelation value of the sampling point at the current time t, n represents the nth sampling point corresponding to the current time t, represents the amplitude of the nth sampling point, m represents the preset delay interval; k is a constant determined according to the number of STF repetition data in the communication protocol; 其中,判断该时刻采样点对应的预设窗口长度内的信号是否是有效信号,包括:Wherein, judging whether the signal within the preset window length corresponding to the sampling point at the moment is a valid signal includes: 计算所述预设窗口长度内的信号中相邻采样点的相位差,获得第一相位差序列;Calculating phase differences between adjacent sampling points in the signal within the preset window length to obtain a first phase difference sequence; 计算所述第一相位差序列中相邻点的差值,获得第二相位差序列;Calculating the differences between adjacent points in the first phase difference sequence to obtain a second phase difference sequence; 对所述第二相位差序列中的值进行累加,获得累积相位差值;Accumulating the values in the second phase difference sequence to obtain a cumulative phase difference value; 比较累积相位差值和预设有效阈值的大小,根据比较结果判断该时刻采样点对应的预设窗口长度内的信号是否是有效信号。The accumulated phase difference value is compared with the preset effective threshold value, and it is determined whether the signal within the preset window length corresponding to the sampling point at the moment is a valid signal according to the comparison result. 2.如权利要求1所述的基于OFDM系统的信号同步方法,其特征在于,根据比较结果判断该时刻采样点对应的预设窗口长度内的信号是否是有效信号,包括:2. The signal synchronization method based on the OFDM system according to claim 1, characterized in that judging whether the signal within the preset window length corresponding to the sampling point at the moment is a valid signal according to the comparison result comprises: 若所述累积相位差值的绝对值小于所述预设有效阈值,则该时刻采样点对应的预设窗口长度内的信号不是有效信号;If the absolute value of the accumulated phase difference is less than the preset effective threshold, the signal within the preset window length corresponding to the sampling point at this moment is not a valid signal; 若所述累积相位差值的绝对值大于所述预设有效阈值,则该时刻采样点对应的预设窗口长度内的信号为有效信号。If the absolute value of the accumulated phase difference is greater than the preset validity threshold, the signal within the preset window length corresponding to the sampling point at this moment is a valid signal. 3.如权利要求1所述的基于OFDM系统的信号同步方法,其特征在于,根据本地参考序列及预设参考系数获得所述预设有效阈值。3. The signal synchronization method based on the OFDM system as described in claim 1 is characterized in that the preset effective threshold is obtained according to a local reference sequence and a preset reference coefficient. 4.如权利要求3所述的基于OFDM系统的信号同步方法,其特征在于,通过以下公式计算所述预设有效阈值:β=k’*λ4. The signal synchronization method based on OFDM system according to claim 3, characterized in that the preset effective threshold is calculated by the following formula: β=k'*λ 其中,β表示预设有效阈值,k’表示本地累积相位差值,λ表示预设参考系数;Wherein, β represents a preset effective threshold, k' represents a local accumulated phase difference value, and λ represents a preset reference coefficient; 其中,本地累积相位差值通过本地参考序列计算,具体包括:The local accumulated phase difference value is calculated by the local reference sequence, specifically including: 计算本地参考序列中相邻采样点的相位差,获得第一本地相位差序列;Calculate the phase differences of adjacent sampling points in the local reference sequence to obtain a first local phase difference sequence; 计算所述第一本地相位差序列中相邻点的差值,获得第二本地相位差序列;Calculating differences between adjacent points in the first local phase difference sequence to obtain a second local phase difference sequence; 对所述第二本地相位差序列中的值进行累加,获得本地累积相位差值。The values in the second local phase difference sequence are accumulated to obtain a local accumulated phase difference value. 5.如权利要求1所述的基于OFDM系统的信号同步方法,其特征在于,基于预设延迟间隔和预设窗口长度,对所述无线信号进行自相关计算,获得每一时刻采样点对应的自相关值,包括:5. The signal synchronization method based on an OFDM system according to claim 1, characterized in that, based on a preset delay interval and a preset window length, performing autocorrelation calculation on the wireless signal to obtain the autocorrelation value corresponding to each sampling point at each moment comprises: 基于预设窗口长度和当前时刻采样点,获得第一信号;其中,第一信号为所述当前时刻采样点对应的所述预设窗口长度内的信号;Based on the preset window length and the current sampling point, a first signal is obtained; wherein the first signal is a signal within the preset window length corresponding to the current sampling point; 基于预设延迟间隔,根据预设取样规则从所述第一信号中获取所述当前时刻采样点对应的自相关计算序列;Based on a preset delay interval, obtaining an autocorrelation calculation sequence corresponding to the sampling point at the current moment from the first signal according to a preset sampling rule; 根据所述当前时刻采样点对应的自相关计算序列,计算所述当前时刻采样点对应的自相关值。According to the autocorrelation calculation sequence corresponding to the sampling point at the current moment, the autocorrelation value corresponding to the sampling point at the current moment is calculated. 6.一种基于OFDM系统的信号同步装置,其特征在于,所述装置包括:6. A signal synchronization device based on an OFDM system, characterized in that the device comprises: 接收单元,用于接收无线信号;A receiving unit, used for receiving wireless signals; 自相关值计算单元,用于基于预设延迟间隔和预设窗口长度,对所述无线信号进行自相关计算,获得每一时刻采样点对应的自相关值;其中,预设窗口长度等于STF的长度;预设延迟间隔等于STF中重复数据段的采样点间隔数;An autocorrelation value calculation unit, configured to perform autocorrelation calculation on the wireless signal based on a preset delay interval and a preset window length, to obtain an autocorrelation value corresponding to a sampling point at each moment; wherein the preset window length is equal to the length of the STF; and the preset delay interval is equal to the number of sampling point intervals of a repeated data segment in the STF; 判断单元,用于若某一时刻采样点对应的自相关值大于预设自相关峰阈值,则判断该时刻采样点对应的预设窗口长度内的信号是否是有效信号;A judgment unit, used to judge whether a signal within a preset window length corresponding to a sampling point at a certain moment is a valid signal if the autocorrelation value corresponding to the sampling point at the moment is greater than a preset autocorrelation peak threshold; 起始位置确定单元,用于若该时刻采样点对应的预设窗口长度内的信号是有效信号,则根据该时刻采样点获得所述无线信号中信号帧的起始位置;A starting position determining unit, configured to obtain a starting position of a signal frame in the wireless signal according to the sampling point at the moment if the signal within a preset window length corresponding to the sampling point at the moment is a valid signal; 其中,通过以下公式计算每一时刻采样点对应的自相关值:Among them, the autocorrelation value corresponding to each sampling point at each moment is calculated by the following formula: , 其中,表示当前t时刻采样点的自相关值,n表示当前t时刻对应的第n个采样点,表示第n个采样点的幅值,m表示预设延迟间隔;k为常数,根据通信协议中STF重复数据的数量确定;in, represents the autocorrelation value of the sampling point at the current time t, n represents the nth sampling point corresponding to the current time t, represents the amplitude of the nth sampling point, m represents the preset delay interval; k is a constant determined according to the number of STF repetition data in the communication protocol; 其中,判断单元包括:The judging unit includes: 第一相位差序列计算单元,用于计算所述预设窗口长度内的信号中相邻采样点的相位差,获得第一相位差序列;A first phase difference sequence calculation unit, used to calculate the phase differences of adjacent sampling points in the signal within the preset window length to obtain a first phase difference sequence; 第二相位差序列计算单元,用于计算所述第一相位差序列中相邻点的差值,获得第二相位差序列;A second phase difference sequence calculation unit, used for calculating the difference between adjacent points in the first phase difference sequence to obtain a second phase difference sequence; 累积相位差值计算单元,用于对所述第二相位差序列中的值进行累加,获得累积相位差值;A cumulative phase difference value calculation unit, used for accumulating the values in the second phase difference sequence to obtain a cumulative phase difference value; 比较判断单元,用于比较所述累积相位差值和预设有效阈值的大小,根据比较结果判断该时刻采样点对应的预设窗口长度内的信号是否是有效信号。The comparison and judgment unit is used to compare the accumulated phase difference value with the preset effective threshold value, and judge whether the signal within the preset window length corresponding to the sampling point at this moment is a valid signal according to the comparison result. 7.如权利要求6所述的基于OFDM系统的信号同步装置,其特征在于,根据比较结果判断该时刻采样点对应的预设窗口长度内的信号是否是有效信号,包括:7. The signal synchronization device based on the OFDM system according to claim 6, characterized in that judging whether the signal within the preset window length corresponding to the sampling point at the moment is a valid signal according to the comparison result comprises: 若所述累积相位差值的绝对值小于所述预设有效阈值,则该时刻采样点对应的预设窗口长度内的信号不是有效信号;If the absolute value of the accumulated phase difference is less than the preset effective threshold, the signal within the preset window length corresponding to the sampling point at this moment is not a valid signal; 若所述累积相位差值的绝对值大于所述预设有效阈值,则该时刻采样点对应的预设窗口长度内的信号为有效信号。If the absolute value of the accumulated phase difference is greater than the preset validity threshold, the signal within the preset window length corresponding to the sampling point at this moment is a valid signal. 8.如权利要求6所述的基于OFDM系统的信号同步装置,其特征在于,根据本地参考序列及预设参考系数获得所述预设有效阈值。8. The signal synchronization device based on the OFDM system as claimed in claim 6, characterized in that the preset effective threshold is obtained according to a local reference sequence and a preset reference coefficient. 9.如权利要求8所述的基于OFDM系统的信号同步装置,其特征在于,通过以下公式计算所述预设有效阈值:β=k’*λ;9. The signal synchronization device based on the OFDM system according to claim 8, characterized in that the preset effective threshold is calculated by the following formula: β=k'*λ; 其中,β表示预设有效阈值,k’表示本地累积相位差值,λ表示预设参考系数;Wherein, β represents a preset effective threshold, k' represents a local accumulated phase difference value, and λ represents a preset reference coefficient; 其中,本地累积相位差值通过所述本地参考序列计算,具体包括:The local accumulated phase difference value is calculated by the local reference sequence, specifically including: 计算本地参考序列中相邻采样点的相位差,获得第一本地相位差序列;Calculate the phase differences of adjacent sampling points in the local reference sequence to obtain a first local phase difference sequence; 计算所述第一本地相位差序列中相邻点的差值,获得第二本地相位差序列;Calculating differences between adjacent points in the first local phase difference sequence to obtain a second local phase difference sequence; 对所述第二本地相位差序列中的值进行累加,获得本地累积相位差值。The values in the second local phase difference sequence are accumulated to obtain a local accumulated phase difference value. 10.如权利要求6所述的基于OFDM系统的信号同步装置,其特征在于,所述自相关值计算单元,包括:10. The signal synchronization device based on OFDM system according to claim 6, characterized in that the autocorrelation value calculation unit comprises: 第一信号获取单元,用于基于预设窗口长度和当前时刻采样点,获得第一信号;其中,第一信号为所述当前时刻采样点对应的所述预设窗口长度内的信号;A first signal acquisition unit, configured to acquire a first signal based on a preset window length and a sampling point at a current moment; wherein the first signal is a signal within the preset window length corresponding to the sampling point at the current moment; 自相关序列采样单元,用于基于预设延迟间隔,根据预设取样规则从所述第一信号中获取所述当前时刻采样点对应的自相关计算序列;An autocorrelation sequence sampling unit, configured to obtain an autocorrelation calculation sequence corresponding to the sampling point at the current moment from the first signal based on a preset delay interval and according to a preset sampling rule; 采样点自相关计算单元,用于根据所述当前时刻采样点对应的自相关计算序列,计算所述当前时刻采样点对应的自相关值。The sampling point autocorrelation calculation unit is used to calculate the autocorrelation value corresponding to the sampling point at the current moment according to the autocorrelation calculation sequence corresponding to the sampling point at the current moment.
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