Power line carrier signal synchronization method and device

Abstract

The present invention discloses a method and device for synchronizing power line carrier signals, belonging to the field of power line carrier communication technology. The method comprises: determining an autocorrelation result based on a known signal sequence when a signal sequence is received; determining a valid correlation peak when the autocorrelation result exceeds a dynamic threshold; dynamically updating the dynamic threshold as the changing trend of multiple autocorrelation results is followed; and initiating signal synchronization when the valid correlation peak and the historical valid correlation peak constitute a continuous correlation peak. The present invention combines cross-correlation with autocorrelation to achieve accurate detection of the valid correlation peak, and introduces a dynamic threshold and continuity verification mechanism, thereby improving the accuracy and robustness of signal synchronization, significantly reducing the synchronization misjudgment rate, and improving synchronization efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and in particular relates to a power line carrier signal synchronization method and device. Background Art

[0002] High-speed Power Line Communication (HPLC) technology utilizes power lines for high-speed data transmission. HPLC systems primarily use cross-correlation for time synchronization. This method cross-correlates the received signal with a known local reference sequence, and the synchronization position is determined based on the peak position of the correlation function.

[0003] However, due to the complex power line channel environment, common background noise, narrowband interference and sudden impulse noise will have a significant impact on the received signal. Under low signal-to-noise ratio conditions, the main peak of the cross-correlation output and the side peaks caused by noise are difficult to distinguish, resulting in synchronization failure; and sudden impulse noise may introduce false peaks, leading to misjudgment of the synchronization position. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the present invention proposes a power line carrier signal synchronization method, apparatus, system, chip, device and storage medium to achieve high robustness and high precision signal synchronization.

[0005] In a first aspect, the present invention provides a method for synchronizing a power line carrier signal, the method comprising:

[0006] In the case of receiving the signal sequence, determining an autocorrelation result based on the known signal sequence;

[0007] Determining a valid correlation peak when the autocorrelation result exceeds a dynamic threshold; the dynamic threshold is dynamically updated according to the changing trend of the multiple autocorrelation results;

[0008] When the effective correlation peak and the historical effective correlation peak constitute continuous correlation peaks, signal synchronization is initiated.

[0009] According to the power line carrier signal synchronization method provided by the present invention, by detecting a signal sequence and, when a signal sequence is received, determining an autocorrelation result based on a known signal sequence, the synchronization feature in the signal can be effectively detected through autocorrelation processing, thereby improving the accuracy and reliability of the synchronization detection; when the autocorrelation result exceeds a dynamic threshold, an effective correlation peak is determined, invalid correlation peaks can be eliminated, and the anti-interference ability of the synchronization detection is improved; and a dynamic threshold mechanism based on the changing trend of the autocorrelation result is adopted, which can adaptively update the threshold, making the identification of the effective correlation peak more accurate; and when the effective correlation peak and the historical effective correlation peak constitute a continuous correlation peak, the stability and consistency of the synchronization signal are ensured by detecting the continuous correlation peak, thereby reliably starting the signal synchronization process, reducing the possibility of misjudgment and missed judgment, achieving efficient and accurate synchronization of the signal in a complex channel environment, and enhancing the robustness and reliability of the signal synchronization.

[0010] According to one embodiment of the present invention, determining a valid correlation peak when an autocorrelation result exceeds a dynamic threshold includes: determining a maximum correlation peak when the autocorrelation result exceeds the dynamic threshold; the peak value of the maximum correlation peak is the current autocorrelation result, and the peak position is the signal position of a sampling point corresponding to the peak value; verifying the validity of the maximum correlation peak, and determining the maximum correlation peak as a valid correlation peak when the validity verification passes.

[0011] According to one embodiment of the present invention, verifying the validity of the maximum correlation peak includes: determining a sampling point interval associated with the maximum correlation peak; the sampling point interval does not include a sampling point corresponding to the peak value of the maximum correlation peak; and determining the signal-to-noise ratio of the maximum correlation peak within the sampling point interval to verify the validity of the maximum correlation peak.

[0012] According to one embodiment of the present invention, determining the signal-to-noise ratio of the maximum correlation peak within the sampling point interval to verify the validity of the maximum correlation peak includes: determining an average autocorrelation result based on the autocorrelation results corresponding to each sampling point within the sampling point interval; determining the signal-to-noise ratio of the peak value of the maximum correlation peak to the average autocorrelation result; wherein the signal-to-noise ratio characterizes the shape of the maximum correlation peak, and the larger the signal-to-noise ratio, the sharper the maximum correlation peak; and determining that the maximum correlation peak is valid when the signal-to-noise ratio exceeds a signal-to-noise ratio threshold.

[0013] According to one embodiment of the present invention, when the autocorrelation result exceeds the dynamic threshold, determining the maximum correlation peak includes: comparing the current autocorrelation result with the dynamic threshold; when the autocorrelation result exceeds the dynamic threshold, updating the dynamic threshold based on the current autocorrelation result to obtain a new dynamic threshold; the new dynamic threshold is used for comparison with the newly obtained autocorrelation result next time; continuing to receive the signal sequence, and returning to the step of comparing the current autocorrelation result with the dynamic threshold to continue executing until the current autocorrelation result does not exceed the dynamic threshold obtained by the most recent update, and obtaining the target dynamic threshold; verifying the validity of the target dynamic threshold, and when the target dynamic threshold is valid, determining the current autocorrelation result as the maximum correlation peak.

[0014] According to one embodiment of the present invention, verifying the validity of the target dynamic threshold includes: determining a preset number of target sampling points after a current sampling point, and respectively determining an autocorrelation result corresponding to each target sampling point; the current sampling point corresponds to the current autocorrelation result; and determining that the target dynamic threshold is valid if the autocorrelation results corresponding to each target sampling point do not exceed the autocorrelation result corresponding to the current sampling point.

[0015] According to one embodiment of the present invention, after determining the effective correlation peak, and when the effective correlation peak and the historical effective correlation peak constitute a continuous correlation peak, before starting signal synchronization, the method further includes: determining a historical effective correlation peak, and determining a first spacing between the historical effective correlation peak and the current effective correlation peak; when the first spacing meets a spacing threshold condition, increasing an adjacent count value; when the first spacing does not meet the spacing threshold condition, resetting the adjacent count value; and when the adjacent count value exceeds a preset count threshold, determining that the effective correlation peak and the historical effective correlation peak constitute a continuous correlation peak.

[0016] According to one embodiment of the present invention, when a signal sequence is received, determining the autocorrelation result based on a known signal sequence includes: performing a cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result; determining a target historical cross-correlation result; and performing an autocorrelation operation on the cross-correlation result and the target historical cross-correlation result to obtain an autocorrelation result.

[0017] According to one embodiment of the present invention, performing a cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result includes: determining a sign coefficient corresponding to each sampling point based on a signal amplitude corresponding to each sampling point in the signal sequence; wherein the positive and negative signs of the signal amplitude are consistent with the positive and negative signs of the sign coefficient; determining a sign sequence corresponding to the signal sequence based on the sign coefficient corresponding to each sampling point; and performing a cross-correlation operation on the sign sequence and the known signal sequence to obtain a cross-correlation result.

[0018] According to one embodiment of the present invention, performing a cross-correlation operation on the symbol sequence and the known signal sequence to obtain a cross-correlation result includes: for any sampling point, multiplying the symbol coefficient corresponding to the sampling point by the known signal at the same position in the known signal sequence to obtain a cross-correlation value corresponding to the sampling point; and obtaining the cross-correlation result based on the sum of the cross-correlation values corresponding to each sampling point in the signal sequence.

[0019] According to one embodiment of the present invention, performing an autocorrelation operation on the mutual correlation result and the target historical mutual correlation result to obtain the autocorrelation result includes: multiplying the mutual correlation result and the target historical mutual correlation result to obtain an autocorrelation value; and obtaining the autocorrelation result based on the absolute value of the autocorrelation value.

[0020] According to one embodiment of the present invention, there is a second interval between the target historical cross-correlation result and the cross-correlation result, and the length of the second interval is the same as the length of the known signal sequence.

[0021] According to one embodiment of the present invention, the signal synchronization step includes: receiving a frame preamble signal; the frame preamble signal includes a synchronization sequence and a flag sequence; whenever a valid correlation peak is determined based on the received synchronization sequence, the received synchronization sequence is subjected to signal conversion processing to obtain a signal conversion result; the signal conversion result is used for channel estimation; and when it is determined that the flag sequence is received, the signal synchronization is ended.

[0022] According to one embodiment of the present invention, the method further includes: determining that a flag sequence is received when the autocorrelation value is determined to be a negative number based on the autocorrelation result corresponding to any valid correlation peak; wherein the boundary position between the synchronization sequence and the flag sequence is the end position of the signal synchronization.

[0023] According to one embodiment of the present invention, the sequence length of the signal sequence is the same as the sequence length of the known signal sequence, and the known signal sequence corresponds to a synchronization sequence.

[0024] In a second aspect, the present invention provides a power line carrier signal synchronization device, the device comprising:

[0025] an operation module, configured to determine an autocorrelation result based on a known signal sequence when a signal sequence is received;

[0026] A processing module, configured to determine a valid correlation peak when the autocorrelation result exceeds a dynamic threshold; the dynamic threshold is dynamically updated according to the changing trend of the plurality of autocorrelation results;

[0027] The synchronization module is used to start signal synchronization when the effective correlation peak and the historical effective correlation peak constitute a continuous correlation peak.

[0028] According to the power line carrier signal synchronization device provided by the present invention, by detecting a signal sequence and, when a signal sequence is received, determining an autocorrelation result based on a known signal sequence, the synchronization feature in the signal can be effectively detected through autocorrelation processing, thereby improving the accuracy and reliability of synchronization detection; when the autocorrelation result exceeds a dynamic threshold, an effective correlation peak is determined, invalid correlation peaks can be eliminated, and the anti-interference ability of synchronization detection is improved; and a dynamic threshold mechanism based on the changing trend of the autocorrelation result is adopted, so that the threshold can be adaptively updated, making the identification of effective correlation peaks more accurate; and when the effective correlation peak and the historical effective correlation peak constitute a continuous correlation peak, the stability and consistency of the synchronization signal are ensured by detecting the continuous correlation peak, thereby reliably starting the signal synchronization process, reducing the possibility of misjudgment and missed judgment, realizing efficient and accurate synchronization of signals in a complex channel environment, and enhancing the robustness and reliability of signal synchronization.

[0029] In a third aspect, the present invention provides a signal synchronization system, comprising:

[0030] A signal transmitting device, configured to transmit a carrier signal; the carrier signal includes a frame preamble signal, a frame control signal, and a data payload;

[0031] A signal receiving device is used to execute and implement the power line carrier signal synchronization method as described in the first aspect, so as to extract the data payload carried in the carrier signal based on the frame control signal after the signal synchronization is completed.

[0032] In a fourth aspect, the present invention provides a chip comprising a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run a program or instruction to implement the power line carrier signal synchronization method as described in the first aspect above.

[0033] In a fifth aspect, the present invention provides a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the power line carrier signal synchronization method as described in the first aspect above is implemented.

[0034] In a sixth aspect, the present invention provides a non-transitory computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the power line carrier signal synchronization method as described in the first aspect above.

[0035] In a seventh aspect, the present invention provides a computer program product, comprising a computer program, which, when executed by a processor, implements the power line carrier signal synchronization method as described in the first aspect above.

[0036] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments with reference to the following drawings, in which:

[0038] Figure 1 is a schematic diagram of the structure of a PPDU signal frame provided in some embodiments of the present invention;

[0039] Figure 2 is a schematic structural diagram of a frame preamble signal provided in some embodiments of the present invention;

[0040] Figure 3 is a schematic structural diagram of a power line carrier signal synchronization system provided in some embodiments of the present invention;

[0041] Figure 4 is a flowchart of a power line carrier signal synchronization method provided in some embodiments of the present invention;

[0042] Figure 5 is a schematic diagram of the principle of the sampling point interval provided in some embodiments of the present invention;

[0043] Figure 6 is a schematic diagram of the shape of the maximum correlation peak provided in some embodiments of the present invention;

[0044] Figure 7 is a flowchart of a power line carrier signal synchronization method provided in some other embodiments of the present invention;

[0045] Figure 8 is a schematic diagram of a cross-correlation result obtained after a cross-correlation operation is performed between a signal sequence and a known synchronization sequence under noise-free conditions provided in some embodiments of the present invention;

[0046] Figure 9 is a schematic diagram of an autocorrelation result obtained after performing an autocorrelation operation based on a cross-correlation result under noise-free conditions provided in some embodiments of the present invention;

[0047] Figure 10 is a schematic diagram of a cross-correlation result obtained after a cross-correlation operation is performed between a signal sequence and a known synchronization sequence under noise interference provided in some embodiments of the present invention;

[0048] Figure 11 is a schematic diagram of an autocorrelation result obtained after performing an autocorrelation operation based on a cross-correlation result under noise interference provided in some embodiments of the present invention;

[0049] Figure 12 is a schematic structural diagram of a power line carrier signal synchronization device provided in some embodiments of the present invention;

[0050] Figure 13 It is a schematic diagram of the structure of a computer device provided in some embodiments of the present invention. DETAILED DESCRIPTION

[0051] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0052] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as commonly understood by those skilled in the art to which the present invention pertains. The terms used in the specification and application of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The terms "including" and "having," as well as any variations thereof, in the specification and claims of the present invention and the accompanying drawings are intended to cover non-exclusive inclusions. The terms "first," "second," etc., in the specification and claims of the present invention and the accompanying drawings are used to distinguish between different objects, rather than to describe a specific order or a primary-secondary relationship.

[0053] References to "embodiments" in this disclosure mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the disclosure. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0054] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0055] The term "and / or" in this disclosure simply describes an association between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this disclosure generally indicates that the related objects are in an "or" relationship.

[0056] The term "multiple" used in the present invention refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple sheets" refers to more than two sheets (including two sheets).

[0057] With the widespread deployment of carrier communication systems such as power line communication (PLC) in smart grids, smart homes, and industrial automation, communication systems are increasingly demanding real-time and reliable data transmission. Orthogonal frequency division multiplexing (OFDM) is a modulation technique widely used in modern communication systems. Its core concept is to decompose a high-speed data stream into multiple parallel, lower-rate subcarrier signals for transmission. Because each subcarrier maintains strict orthogonality in the frequency domain, OFDM technology not only effectively improves spectrum utilization but also provides excellent resistance to multipath interference.

[0058] However, to maintain orthogonality between subcarriers, OFDM systems require extremely high accuracy in time and frequency synchronization. Especially at the receiving end, if the synchronization deviation is large, the orthogonality between subcarriers will be destroyed, causing severe inter-symbol interference (ISI) and inter-carrier interference (ICI), which will seriously affect the demodulation performance.

[0059] In such systems, signal synchronization, a critical prerequisite for ensuring frame-level reception accuracy, has a direct impact on the stability and efficiency of the entire communication process. Traditional synchronization algorithms, particularly in low signal-to-noise ratio environments or strong interference scenarios, often struggle to balance peak identification accuracy, synchronization latency, and computational complexity, leading to missed communication frames or synchronization failures, severely hindering further improvements in system performance.

[0060] On the other hand, current mainstream synchronization methods focus on detecting sudden changes in the cross-correlation function at specific locations, or rely on fixed thresholds to determine correlation peaks. This approach lacks flexibility in adapting to varying channel conditions and is prone to misjudgments or missed detections. To achieve a more robust and adaptive frame synchronization process, a signal synchronization mechanism is urgently needed that can dynamically respond to channel changes, improve the reliability of peak detection, and effectively control synchronization delays.

[0061] In view of this, the present invention proposes a power line carrier signal synchronization method based on a joint judgment mechanism of cross-correlation and autocorrelation. This method not only improves the robustness and accuracy of synchronization judgment, but also reduces the computational complexity to a certain extent by introducing technical means such as symbol processing, dynamic threshold update and continuous peak verification. It is particularly suitable for synchronization detection under low signal-to-noise ratio.

[0062] The power line carrier signal synchronization method and the like provided by the embodiments of the present invention will be described in detail below with reference to the accompanying drawings through specific embodiments and their application scenarios.

[0063] Industry technical specifications for HPLC systems detail the physical layer, data link layer, and application layer protocols of broadband carrier communication standards, as well as related verification specifications. In these specifications, OFDM symbols are typically transmitted sequentially as individual PPDU (Physical Protocol Data Unit) frames.

[0064] Figure 1 1 is a schematic diagram of the structure of the PPDU signal frame provided in some embodiments of the present invention. Figure 1 As shown in the figure, a PPDU frame typically consists of a preamble, a frame control (FC), and a payload (PL). The preamble is used for frame synchronization and channel estimation. The FC describes basic frame information, such as modulation scheme and subcarrier distribution. The payload describes the actual data to be transmitted.

[0065] Figure 2 : is a schematic diagram of the structure of the frame preamble signal provided in some embodiments of the present invention. Wherein, the frame preamble signal is a periodic sequence known to both the sender and the receiver, such as Figure 2 As shown in the figure, the SYNCP (Synchronization Pattern) provides a synchronization signal to the receiver, helping it identify the start of a frame. This is also known as the synchronization sequence. The SYNCM (Synchronization Marker) marks the end of a frame and is also known as the flag sequence. The Repetition Interval (RI) is a gap or interval within the preamble frame to prevent interference or overlap between preamble symbols.

[0066] Generally speaking, a frame preamble signal includes 10.5 SYCNP sequences and 2.5 SYNCM sequences. Each SYCNP sequence includes 1024 sampling point signals, and each SYNCM sequence includes 1024 sampling point signals.

[0067] During data transmission, data is first organized into logical frames in the upper layer protocol. The logical frames are encapsulated into PPDU frames and transmitted to the physical layer. The physical layer performs OFDM modulation on the PPDU frames and sends them as a continuous signal through the power line.

[0068] Figure 3 The power line carrier signal synchronization method provided by the present invention can be applied to the following examples: Figure 3 The signal synchronization system shown in FIG. The signal synchronization system includes a signal transmitting device and a signal receiving device. The signal transmitting device is used to transmit a carrier signal. The carrier signal includes a frame preamble signal, a frame control signal, and a data payload.

[0069] Exemplarily, the signal sending device receives data from the data link layer, processes and transforms the power carrier signal in a series of steps, processes the encoded data using OFDM modulation, modulates the frame preamble signal, frame control signal and data payload to form an OFDM signal, also known as a carrier signal, and sends the carrier signal to the power line.

[0070] After detecting a signal from the power line, the signal receiving device enters a frame synchronization state, precisely locating the frame synchronization position for subsequent data frame extraction, such as extracting the frequency domain features required for channel estimation. Upon detecting the SYNCM sequence, or flag sequence, the final frame synchronization is achieved, and the starting position of the frame control signal is determined, completing signal synchronization. After signal synchronization is complete, the signal receiving device extracts the data payload carried by the carrier signal based on the frame control signal, and decodes and demodulates it to restore the decoded data information, which is ultimately sent to the data link layer for subsequent protocol analysis.

[0071] The signal transmitting device and the signal receiving device may be, for example, a computer device, which may be a power line communication terminal, a concentrator device, a smart meter, a device with an embedded communication module, or a communication test terminal. Alternatively, the computer device may be a device or intelligent robot with computing capabilities, configured to perform the signal acquisition, processing, and synchronization steps of the present invention.

[0072] During signal synchronization, the present invention performs cross-correlation processing based on a locally known sequence and the received signal sequence, while also introducing an autocorrelation mechanism to identify potential correlation peaks. During detection, the correlation peak is precisely located by continuously tracking the maximum absolute value of the autocorrelation, effectively eliminating false correlation peaks. Signal synchronization is initiated by detecting multiple consecutive valid correlation peaks, further enhancing the robustness of signal synchronization.

[0073] The power line carrier signal synchronization method provided by the present invention can adaptively process complex channel characteristics such as burst noise and periodic interference in the power line. It is suitable for smart grid communications, industrial automation, home broadband power line networks and other wireless or wired communication systems based on OFDM modulation, and has wide practicality and promotion value.

[0074] The power line carrier signal synchronization method provided by the present invention can be executed by a signal receiving device, or a functional module or functional entity in the signal receiving device that can implement the method.

[0075] The power line carrier signal synchronization method provided by the present invention is described below by taking a signal receiving device as an example of an execution subject.

[0076] Figure 4 FIG. 1 is a flow chart of a power line carrier signal synchronization method provided in some embodiments of the present invention. Figure 4 As shown, the power line carrier signal synchronization method includes: step 420, step 440 and step 460.

[0077] Step 420: When a signal sequence is received, determine an autocorrelation result based on a known signal sequence.

[0078] A signal sequence is a set of sampling point signals of a certain length arranged in chronological order. A sampling point refers to the signal value obtained at a certain sampling period when sampling a continuous signal. The sampling period can be determined based on actual conditions.

[0079] The signal receiving device can generally obtain discrete sampling points by sampling the continuous signal at uniform time intervals, and a set of a preset number of discrete sampling points forms a signal sequence. For example, the length of the signal sequence is 1024 sampling points.

[0080] Alternatively, the signal receiving device may set a sliding window of a certain length, and the signal within the sliding window is the current signal sequence. The length of the sliding window may be 1024, corresponding to 1024 sampling point signals.

[0081] For the received signal sequence, the signal receiving device performs a correlation evaluation based on the known signal sequence to obtain an autocorrelation value. The autocorrelation value has a positive or negative sign, and the absolute value of the autocorrelation value is referred to as the autocorrelation result. The known signal sequence refers to a predetermined signal sequence. In embodiments of the present invention, the known signal sequence may be a locally stored synchronization sequence, i.e., a local SYNCP sequence.

[0082] For example, a signal receiving device performs sliding matching on a received signal sequence, calculating the cross-correlation between each sampling point in the signal sequence and the known signal sequence to characterize the correlation between the two. Each sampling point corresponds to a cross-correlation result, and the entire cross-correlation process outputs a continuous cross-correlation sequence.

[0083] To improve the accuracy and computational efficiency of cross-correlation matching, the input signal sequence used for matching is typically required to be consistent in length with the local synchronization sequence. To this end, the signal sequence length is the same as the known signal sequence length, and the known signal sequence corresponds to the synchronization sequence. This maximizes the preservation of signal correlation characteristics, avoids recognition errors caused by data truncation or alignment deviation, and reduces unnecessary consumption of computing resources. For example, the length of both the signal sequence and the local SYNCP sequence is 1024.

[0084] In one approach, since autocorrelation is the cross-correlation between a signal and itself, the autocorrelation result can be obtained by calculating the cross-correlation between the signal and itself. Cross-correlation is used to measure the degree of correlation between a received signal sequence and a known signal sequence, and is typically determined by calculating the sum of the products of the received signal sequence and the known signal sequence. Therefore, the signal receiving device can first perform a cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result. Each time a cross-correlation result is calculated, the signal receiving device stores it, and can subsequently perform an autocorrelation operation on the cross-correlation result with the cross-correlation results calculated historically to obtain an autocorrelation result.

[0085] In another way, the signal receiving device can establish a neural network or machine learning model related to the signal sequence through the mapping relationship between the historical signal sequence and the known signal sequence, and after the training is completed, use the current signal sequence as input to obtain the autocorrelation result output by the neural network or machine learning model.

[0086] In another embodiment, the signal receiving device may also extract a portion containing a known signal sequence from the received signal sequence and perform an autocorrelation operation on the portion, for example, calculating the sum of products between the signal of each sampling point and the signal of the sampling point after a certain time delay to obtain an autocorrelation result.

[0087] Step 440: When the autocorrelation result exceeds a dynamic threshold, a valid correlation peak is determined; the dynamic threshold is dynamically updated according to the changing trend of the multiple autocorrelation results.

[0088] When there is a large correlation between the signal sequence and the known signal sequence, the autocorrelation results of each sampling point obtained in combination with the history will show a peak shape from the data distribution, that is, the autocorrelation peak, referred to as the correlation peak.

[0089] A correlation peak is a peak value that appears during autocorrelation processing, indicating that two signals, or a signal itself, have the greatest correlation at a specific time delay. For example, in the first method described above, a correlation peak indicates that the cross-correlation result at a particular sampling point has the greatest correlation with the cross-correlation result at another sampling point calculated historically.

[0090] If the autocorrelation result exceeds the dynamic threshold, it indicates that the current autocorrelation result is likely at a peak. The signal receiving device can then determine the maximum correlation peak based on the current autocorrelation result. Each time the maximum correlation peak is sought, the dynamic threshold starts at an initial dynamic threshold and is dynamically updated based on the changing trends of multiple autocorrelation results. This threshold reaches a maximum value, indicating that the autocorrelation result also reaches a maximum value. At this point, the current autocorrelation result is likely a maximum correlation peak.

[0091] Because pulse signals or sudden noise may exist in power line communication, correlation peaks may appear in the signal sequence even if the signal sequence is not correlated with the known signal sequence. Therefore, in order to screen out the true correlation peak, the detected maximum correlation peak needs to be further verified to obtain a valid correlation peak. For example, the signal receiving device can determine whether the current sampling point is the true maximum correlation peak based on the autocorrelation results of other sampling points in the area near the current sampling point. If the current sampling point is determined to be the true maximum correlation peak, the signal receiving device determines a valid correlation peak. After that, the signal receiving device can determine the next valid correlation peak.

[0092] In actual power line communications, noise interference can affect the determination of the maximum correlation peak. Therefore, in embodiments of the present invention, an initial dynamic threshold is set. During each search for the maximum correlation peak, this initial dynamic threshold is dynamically adjusted and updated based on the changing trend of the autocorrelation results at each sampling point, thereby adaptively detecting the maximum correlation peak within a certain sampling point interval. The changing trend of the autocorrelation result represents the pattern or direction of the autocorrelation result's change over time or with the sampled signal, such as a continuous increase, a continuous decrease, or oscillation.

[0093] In some embodiments, the signal receiving device repeatedly performs a maximum correlation peak search process during the entire frame synchronization process; repeatedly performs a maximum correlation peak search process during the signal sequence reception process; during each maximum correlation peak search process, the autocorrelation result based on the current sampling point is compared with a dynamic threshold, and the dynamic threshold is updated based on the comparison result until the maximum correlation peak in the current search process is determined; wherein the dynamic threshold at the beginning of each search process is an initial value; after each maximum correlation peak is determined, the subsequent signal sequence is continued to be received and the maximum correlation peak search process is restarted until frame synchronization is completed and signal synchronization is entered. The maximum correlation peak search process can be performed synchronously or asynchronously with the reception of the signal sequence.

[0094] In other words, when the signal receiving device continuously receives the signal sequence, there will be multiple processes of searching for the maximum correlation peak. For example, when receiving the sampling point signal, the signal receiving device determines whether it is the maximum correlation peak. If not, it continues to search backward until the first maximum correlation peak is found, and then starts searching for the next maximum correlation peak... until the frame synchronization position is found and signal synchronization is started.

[0095] At the beginning of each maximum correlation peak judgment process, the signal receiving device starts comparison and updates with the same initial dynamic threshold, and the dynamic threshold finally determined in the judgment process of each maximum correlation peak can be the same or different to adapt to channel characteristics or noise changes.

[0096] For example, at each sampling point, the signal receiving device calculates the corresponding autocorrelation result and compares it with the currently set dynamic threshold. If the autocorrelation result exceeds the dynamic threshold, the threshold is updated and the autocorrelation results of subsequent sampling points are compared. When a sampling point is detected to meet the maximum correlation peak determination condition (for example, the autocorrelation values of several subsequent sampling points do not exceed its current value), this point is confirmed as the maximum correlation peak in a search process. At this time, the signal receiving device records the sampling point position corresponding to the maximum correlation peak, and then continues to receive signals and repeats the above search process. In the new round of maximum correlation peak search process, the initial threshold is used as the starting point, and the autocorrelation comparison, threshold update, and maximum peak determination are repeated until it is detected that the frame synchronization condition is met.

[0097] Therefore, by introducing the dynamic threshold adjustment and maximum correlation peak detection mechanism in the local area, the robustness and adaptability of correlation peak judgment in signal synchronization are enhanced, the impact of noise interference on signal synchronization is reduced, and the accuracy and robustness of signal synchronization detection can be improved.

[0098] Step 460: When the effective correlation peak and the historical effective correlation peak constitute continuous correlation peaks, start signal synchronization.

[0099] Among them, the historical effective correlation peak refers to the effective correlation peak detected in the previous signal processing. Continuous correlation peaks refer to correlation peaks that appear continuously at the expected interval, and continuous correlation peaks can be used to indicate periodic signals. In order to distinguish them, the interval between the historical effective correlation peak and the current effective correlation peak is called the first interval. If the two effective correlation peaks are not continuous, for example, the first interval between the two exceeds the interval threshold or there is an invalid correlation peak in the middle, it is possible that one or more signal sequences are missed during the signal synchronization process. If signal synchronization is performed directly, it will lead to inaccurate signal reception.

[0100] Therefore, in the embodiment of the present invention, the signal receiving device further detects continuous correlation peaks and utilizes the judgment strategy of continuous correlation peaks to further enhance the robustness of the synchronization process, reduce the possibility of misjudgment and missed judgment, and is particularly suitable for complex and changeable communication environments.

[0101] Specifically, for any current valid correlation peak, the signal receiving device judges it together with the historical valid correlation peaks to determine whether it and the historical valid correlation peaks constitute a continuous correlation peak. t-2 , historical effective correlation peak P t-1 and the current effective correlation peak P t If the distance between any two effective correlation peaks does not exceed the distance threshold, the signal receiving device determines the effective correlation peak P t With the historical effective correlation peak P t-1 and P t-2 There can be multiple historical valid correlation peaks. Generally speaking, a greater number means stricter conditions for determining the continuous correlation peaks.

[0102] Detecting consecutive correlation peaks typically indicates a repetitive pattern in the received signal that is highly similar to a known local signal sequence, corresponding to the periodic occurrence of the synchronization sequence SYNCP in the frame preamble. In other words, the received signal exhibits high correlation with the known local signal sequence at multiple locations, indicating that the start of the frame preamble has likely been successfully located.

[0103] Furthermore, if the valid correlation peak forms a continuous correlation peak with the historical valid correlation peak, the signal receiving device can initiate signal synchronization and continue searching backward for valid correlation peaks. When a negative valid correlation peak is obtained, it indicates that the marker sequence SYNCM has been detected, indicating that frame synchronization is complete. The signal receiving device then uses the boundary between the synchronization sequence SYNCP and the marker sequence SYNCM as the final position for frame synchronization, completing frame synchronization.

[0104] After frame synchronization is complete, the signal receiving device can extract the data payload carried by the carrier signal based on the frame control signal. For example, the signal receiving device locates and parses the frame control signal to extract important information about the frame structure and content, such as frame type, length, modulation method, and coding scheme. Based on the information provided by the frame control signal, the signal receiving device can then demodulate the received signal according to the modulation method indicated by the frame control signal to recover the baseband signal. Alternatively, the signal receiving device can decode the demodulated signal according to the coding scheme indicated by the frame control signal to correct any errors that may have occurred during transmission and recover the original data payload.

[0105] According to the power line carrier signal synchronization method provided by the present invention, by detecting a signal sequence and, when a signal sequence is received, determining an autocorrelation result based on a known signal sequence, the synchronization feature in the signal can be effectively detected through autocorrelation processing, thereby improving the accuracy and reliability of the synchronization detection; when the autocorrelation result exceeds a dynamic threshold, an effective correlation peak is determined, invalid correlation peaks can be eliminated, and the anti-interference ability of the synchronization detection is improved; and a dynamic threshold mechanism based on the changing trend of the autocorrelation result is adopted, which can adaptively update the threshold, making the identification of the effective correlation peak more accurate; and when the effective correlation peak and the historical effective correlation peak constitute a continuous correlation peak, the stability and consistency of the synchronization signal are ensured by detecting the continuous correlation peak, thereby reliably starting the signal synchronization process, reducing the possibility of misjudgment and missed judgment, achieving efficient and accurate synchronization of the signal in a complex channel environment, and enhancing the robustness and reliability of the signal synchronization.

[0106] Before performing signal synchronization determination, the signal receiving device should be capable of real-time monitoring of the channel status and, based on this, determine whether a signal sequence is present to be received, thereby triggering the subsequent synchronization detection process. To this end, in some embodiments, before step 420, the power line carrier signal synchronization method provided by the present invention further includes step 410: monitoring the power line channel and determining whether a signal sequence is detected.

[0107] In this embodiment, the signal receiving device can continuously monitor the signal amplitude or power level in the power line channel and compare it with a preset noise threshold. When the signal strength exceeds the background noise threshold for a certain period of time or meets specific characteristics, it is considered that a possible signal sequence has been detected, and the subsequent cross-correlation and autocorrelation processing stages are then initiated.

[0108] The specific features include but are not limited to rising edges, power mutations, or spectrum features.

[0109] For example, the signal receiving device samples the power line voltage signal at regular intervals and accumulates the signal energy value over a sampling window (e.g., 1024 points). If the energy value exceeds the noise threshold for three consecutive windows, it is determined that a signal sequence has been detected, and steps 420 through 460 are executed to proceed with the subsequent signal synchronization process.

[0110] In the above embodiment, by predicting whether a signal is received, the synchronization process is avoided from being entered incorrectly in a no-signal state, the system efficiency is improved, and the system power consumption is saved. At the same time, it can effectively distinguish the communication signal in the power line from the environmental noise or instantaneous interference, and reduce the possibility of false triggering of frame synchronization.

[0111] In HPLC, signal synchronization is a key technology for ensuring accurate data transmission and reception. Conventional synchronization methods using cross-correlation perform poorly in power line communication environments with strong noise interference, such as narrowband interference, background noise, and low signal-to-noise ratios, making them difficult to meet the requirements of high-reliability communication. Therefore, the present invention proposes a method for calculating autocorrelation results that combines cross-correlation and autocorrelation operations to improve the accuracy and robustness of signal synchronization.

[0112] To this end, in some embodiments, in step 420, when a signal sequence is received, determining an autocorrelation result based on a known signal sequence includes steps 422 to 426:

[0113] Step 422: performing a cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result;

[0114] Step 424: Determine the target history cross-correlation result;

[0115] Step 426: Perform an autocorrelation operation on the cross-correlation result and the target history cross-correlation result to obtain an autocorrelation result.

[0116] In this embodiment, the signal receiving device performs a cross-correlation operation on the received signal sequence with a locally known signal sequence to obtain a cross-correlation result for each sampling point in the signal sequence. The known signal sequence is, for example, a known synchronization sequence SYNCP. The cross-correlation result may be, for example, the sum of the products of the signal value of each sampling point in the signal sequence and the signal value of each sampling point in the known signal sequence.

[0117] For example, a signal receiving device performs sliding matching on a received signal sequence, calculating the cross-correlation between each sampling point in the signal sequence and the known signal sequence to characterize the correlation between the two. Each sampling point corresponds to a cross-correlation result, and the entire cross-correlation process outputs a continuous cross-correlation sequence.

[0118] Whenever a cross-correlation result of a sampling point is calculated, the signal receiving device saves it. For example, the signal receiving device can maintain a buffer in memory to store the cross-correlation results of multiple sampling points over a period of time for subsequent analysis.

[0119] For the cross-correlation result at the current sampling point, the signal receiving device extracts a target historical cross-correlation result from the historical cross-correlation results, performs an autocorrelation operation on the current cross-correlation result and the target historical cross-correlation result, calculates an autocorrelation value, and obtains the autocorrelation result at the current sampling point. The autocorrelation result may be, for example, the product of the cross-correlation result at the current sampling point and the target historical cross-correlation result (corresponding to the cross-correlation result at the target historical sampling point).

[0120] In the above embodiment, by combining cross-correlation and autocorrelation operations and performing autocorrelation operations on the current cross-correlation results and historical data, the correlation peak can be more significantly highlighted, thereby more accurately identifying repeated synchronization patterns, thereby improving the accuracy and reliability of synchronization detection.

[0121] In communication systems based on orthogonal frequency division multiplexing (OFDM) technology, such as high-speed power line communication (PLC), accurate frame synchronization is required at the receiving end to effectively decode the received signal. Cross-correlation is a commonly used synchronization detection method. By calculating the similarity between the received signal sequence and a locally stored known signal sequence, the starting position of the synchronization sequence in the received signal can be located. However, in PLC scenarios, because the signal is susceptible to interference factors such as burst noise, narrowband interference, and background noise, traditional amplitude-dependent cross-correlation methods may be unsuitable for practical applications with limited hardware resources or harsh channel conditions due to complex multiplication calculations and sensitivity to amplitude fluctuations.

[0122] Furthermore, signal synchronization efficiency is also crucial in high-speed power line carrier communications. Conventional cross-correlation operations, which multiply a received signal sequence with a locally known signal sequence, consume significant computational resources and are inefficient.

[0123] In view of this, in some embodiments, in step 422, a cross-correlation operation is performed on the signal sequence and the known signal sequence to obtain a cross-correlation result, including steps 4222 to 4226:

[0124] Step 4222: Determine a sign coefficient corresponding to each sampling point based on the signal amplitude corresponding to each sampling point in the signal sequence; wherein the sign of the signal amplitude is consistent with the sign of the sign coefficient;

[0125] Step 4224: Determine a symbol sequence corresponding to the signal sequence based on the symbol coefficients corresponding to each sampling point;

[0126] Step 4226: Perform a cross-correlation operation on the symbol sequence and the known signal sequence to obtain a cross-correlation result.

[0127] In this embodiment, for a received signal sequence, the signal receiving device determines a symbol coefficient corresponding to each sampling point according to the signal amplitude corresponding to each sampling point in the signal sequence.

[0128] The sign of the coefficient corresponds to the sign of the signal amplitude. In other words, each sign coefficient represents the polarity of the signal amplitude at that sampling point, with +1 representing a positive value, −1 representing a negative value, and 0 representing zero or approximately zero.

[0129] For example, the signal receiving device receives a signal sequence of 1024 length, including 1024 sampling points. The signal receiving device then takes the sign coefficient of the signal corresponding to the sampling point signal as +1 if the amplitude is positive; and takes the sign coefficient as -1 if the amplitude is negative. In this way, the sign coefficient corresponding to each sampling point can be quickly obtained. The sign coefficients corresponding to each sampling point constitute a symbol sequence corresponding to the signal sequence, such as {+1, +1, -1, ..., +1, -1}, etc.

[0130] Furthermore, the signal receiving device can perform cross-correlation operations based on the symbol sequence and the known signal sequence. Since only the symbol coefficients corresponding to each sampling point are taken, during the cross-correlation operation, the multiplication operation between the symbol sequence corresponding to the signal sequence and the known signal sequence is converted into a simple addition and subtraction operation, which greatly reduces the amount of calculation.

[0131] In the above embodiment, by simplifying the amplitude of the received signal to its corresponding symbol coefficient and retaining only the positive and negative polarities, compared with the traditional cross-correlation operation in which the specific amplitude is multiplied, the computational complexity and dependence on the amplitude accuracy are effectively reduced, the processing efficiency is improved, and the stability and real-time performance of the synchronous identification are enhanced.

[0132] In some embodiments, in step 4226, a cross-correlation operation is performed on the symbol sequence and the known signal sequence to obtain a cross-correlation result, including: for any sampling point, multiplying the symbol coefficient corresponding to the sampling point with the known signal at the same position in the known signal sequence to obtain a cross-correlation value corresponding to the sampling point; and obtaining a cross-correlation result based on the sum of the cross-correlation values corresponding to each sampling point in the signal sequence.

[0133] In this embodiment, for any sampling point in the received symbol sequence, the signal receiving device extracts the corresponding symbol coefficient, such as +1, -1, or 0. The signal receiving device multiplies the symbol coefficient with the symbol at the same position in the known signal sequence to obtain the cross-correlation value corresponding to the current sampling point.

[0134] Afterwards, the signal receiving device sums the cross-correlation values of each sampling point in the entire signal sequence, and the obtained sum is the cross-correlation result between the current signal sequence and the known sequence.

[0135] Take a sliding window with a length of 1024 points as an example: first, extract the 1024 sampling points covered by the current sliding window from the received signal sequence; calculate the symbol coefficients of the amplitudes of these 1024 sampling points one by one to form a symbol sequence with a length of 1024; then, multiply this symbol sequence with the locally stored SYNCP sequence point by point, and calculate the product at each pair of positions; sum up these 1024 product values to obtain a cross-correlation result value, which serves as the cross-correlation index corresponding to the current sliding window position; repeat the above process, and update the cross-correlation result sequence as the sliding window moves.

[0136] In the above embodiment, by converting the signal amplitude into a sign coefficient, floating-point multiplication calculation is avoided, the amount of calculation is greatly reduced, the processing efficiency is improved, and the correlation peak can be effectively identified even in a low signal-to-noise ratio environment, thereby improving the synchronization robustness. In addition, since only the positive and negative sign coefficients of the signal are taken, the hardware implementation difficulty and processing delay are also greatly reduced, which is suitable for deployment in resource-constrained communication terminals or embedded platforms.

[0137] In traditional schemes, autocorrelation calculations often rely on the original received signal itself, resulting in high computational complexity and susceptibility to interference from channel perturbations and noise. To address this, the present invention proposes an autocorrelation calculation method based on the cross-correlation result and its historical value. This method multiplies the current cross-correlation value by the historical cross-correlation value to form an autocorrelation value. The absolute value of the autocorrelation value is then used as the autocorrelation strength, thereby constructing an indicator for determining the significance of correlation peaks. This method reduces computational complexity and improves detection accuracy.

[0138] To this end, in some embodiments, in step 426, an autocorrelation operation is performed on the mutual correlation result and the target historical mutual correlation result to obtain an autocorrelation result, including: multiplying the mutual correlation result and the target historical mutual correlation result to obtain an autocorrelation value; and obtaining the autocorrelation result based on the absolute value of the autocorrelation value.

[0139] To ensure that the current cross-correlation result and the historical data reflect the synchronization sequence matching results of the same round or the same structure, in some embodiments, there is a preset interval between the target historical cross-correlation result and the cross-correlation result, called the second interval, and the length of the second interval is the same as the length of the known signal sequence.

[0140] In this way, the two can reflect two adjacent or repeated synchronization sequence matching points (for example, ensuring that the two mutual correlation values respectively reflect the SYNCP segments of two adjacent cycles in the received signal), thereby improving the representativeness and stability of the autocorrelation result and reducing the false detection rate.

[0141] In some embodiments, the current cross-correlation result is calculated over a sliding window between the symbol sequence corresponding to the currently received signal sequence and a locally known signal sequence (e.g., a SYNCP sequence). The target historical cross-correlation result may be the cross-correlation result calculated several positions (e.g., 1024 points ago) ahead of the sliding window.

[0142] The signal receiving device multiplies the current cross-correlation result with the target's historical cross-correlation result to obtain the autocorrelation value at the corresponding location. The signal receiving device then takes the absolute value of the autocorrelation value as the autocorrelation strength indicator at that location, which is used to determine whether there is a significant peak that matches the known signal sequence.

[0143] It is easy to understand that the above process can be repeatedly executed under the sliding window mechanism, so that the system can monitor the repeatability of the cross-correlation results in real time, and then identify potential synchronization points. The autocorrelation results can be continuously updated, which is suitable for dynamic detection and can improve the response efficiency and accuracy of the synchronization process.

[0144] For example, at the i-th sliding window position, the signal receiving device calculates the cross-correlation value Corr_i. Furthermore, the signal receiving device records the historical cross-correlation result Corr_i-1024 at the (i-1024)-th sliding window position. The signal receiving device then multiplies Corr_i by Corr_i-1024 to obtain an autocorrelation value AutoCorrVal = Corr_i × Corr_i-1024. Furthermore, the signal receiving device takes the absolute value of this value to obtain the autocorrelation result AbsAutoCorr = |AutoCorr|.

[0145] In the above embodiment, by autocorrelating the current cross-correlation result with the historical cross-correlation result, it is possible to determine whether the synchronization sequence continues to appear in multiple cycles, and the correlation peak can be identified more quickly and accurately; and, by using the absolute value of the autocorrelation value as an autocorrelation strength indicator, the error caused by the change in symbol polarity can be effectively filtered out, thereby improving the recognition accuracy in a strong interference environment.

[0146] In signal synchronization based on cross-correlation and autocorrelation mechanisms, determining valid correlation peaks is crucial for synchronization accuracy. Traditional cross-correlation detection often relies solely on determining correlation by checking whether a single peak exceeds a fixed threshold. However, in complex channel environments with strong interference and low signal-to-noise ratios, such as power line communications, noise can easily induce false peaks, leading to synchronization misjudgment.

[0147] To this end, in some embodiments, in step 440, when the autocorrelation result exceeds the dynamic threshold, determining a valid correlation peak includes steps 442 to 444:

[0148] Step 442: If the autocorrelation result exceeds the dynamic threshold, determine the maximum correlation peak; the peak value of the maximum correlation peak is the current autocorrelation result, and the peak position is the signal position of the sampling point corresponding to the peak value;

[0149] Step 444: Verify the validity of the maximum correlation peak, and if the validity verification passes, determine the maximum correlation peak as a valid correlation peak.

[0150] As previously mentioned, as a signal receiving device continuously receives a signal sequence, it will search for the maximum correlation peak multiple times. For example, upon receiving a sampling point signal, the signal receiving device determines whether it is the maximum correlation peak. If not, it continues searching until a maximum correlation peak is found. In this embodiment, the process of searching for the maximum correlation peak is described as follows. The signal receiving device compares the current autocorrelation result with the dynamic threshold to find the point with the maximum peak value of the autocorrelation result within a certain area. The peak amplitude and corresponding position of this point are used as the current maximum correlation peak, and the dynamic threshold is updated based on the current autocorrelation result. For the next sampling point, the signal receiving device compares the autocorrelation result of the next sampling point with the previously updated dynamic threshold. If the autocorrelation result of the next sampling point exceeds the previously updated dynamic threshold, the previously updated dynamic threshold is continuously updated for use in the next comparison. Thus, by continuously updating the dynamic threshold, the most significant correlation peak can be selected from multiple possible correlation peaks, thereby enhancing the stability of synchronization judgment.

[0151] For example, the signal receiving device iterates over the autocorrelation values of all sampling points in the current sliding window. If the autocorrelation value exceeds the current dynamic threshold, it continuously records the maximum value of the peak and its corresponding position. Whenever a higher autocorrelation value appears, the signal receiving device updates the current maximum value and peak position until the traversal is complete or the autocorrelation value stops rising. The maximum correlation peak in the current segment is then determined.

[0152] Subsequently, the signal receiving device verifies the validity of the maximum correlation peak using a set peak validity condition. Validity verification may be based on, but is not limited to, the ratio of the maximum correlation peak to the background noise level, the persistence of the peak, and other optional statistical indicators.

[0153] For example, the signal receiving device selects a predetermined sampling range after the maximum correlation peak as a background reference interval and calculates the average autocorrelation value within this interval, comparing it with the maximum correlation peak. If the ratio exceeds a preset threshold, the peak is considered significant and can be determined to be a valid correlation peak.

[0154] In the above embodiment, by screening for the maximum correlation peak rather than the peak that first exceeds the threshold, the system avoids mistakenly identifying non-maximum points with high fluctuations as valid correlation peaks. This allows for stable and accurate identification of true synchronization markers under conditions of complex channel interference and large signal-to-noise ratio fluctuations, thereby improving the robustness and accuracy of frame synchronization. Furthermore, high-quality identification of valid correlation peaks facilitates subsequent identification of consecutive correlation peaks, enabling smoother entry into frame synchronization.

[0155] The verification of the validity of the maximum correlation peak in step 444 includes steps 4442 to 4444:

[0156] Step 4442: Determine the sampling point interval associated with the maximum correlation peak; the sampling point interval does not include the sampling point corresponding to the peak value of the maximum correlation peak;

[0157] Step 4444: Determine the signal-to-noise ratio of the maximum correlation peak within the sampling point interval to verify the validity of the maximum correlation peak.

[0158] In this embodiment, after detecting the maximum correlation peak, the signal receiving device calculates the signal-to-noise ratio in the area based on the sampling point interval around the peak to assist in determining whether the correlation peak has sufficient significance.

[0159] The signal receiving device first determines a sampling point interval corresponding to the maximum correlation peak. This interval is typically a preset length interval (e.g., 1000 sampling points) after the sampling point where the maximum correlation peak occurs, such as a sampling point interval offset by a fixed length (e.g., 20 to 50 sampling points). Furthermore, this sampling point interval does not include the peak sampling point of the maximum correlation peak to prevent it from interfering with background noise determination.

[0160] The signal receiving device calculates the average or other statistical value of the autocorrelation results within the sampling point interval as a background noise reference. Combined with the absolute value of the autocorrelation of the maximum correlation peak, the signal receiving device can calculate the signal-to-noise ratio between it and the background reference.

[0161] The signal-to-noise ratio (SNR) can be used to measure whether a correlation peak is sufficiently prominent in the background noise, thus serving as a basis for determining whether it is a valid correlation peak. When the SNR exceeds a preset threshold, the correlation peak is considered to have good significance and is thus determined to be a valid correlation peak.

[0162] Figure 5 Schematic diagram of the principle of the sampling point interval provided in some embodiments of the present invention. Figure 5As shown in the figure, starting from the maximum correlation peak, the signal receiving device shifts backward by 20 sampling points and calculates the absolute mean of the autocorrelation values corresponding to 1000 sampling points within the sampling interval as the noise background. The signal receiving device then compares the maximum correlation peak with this background mean. If the ratio exceeds a set threshold, the peak is considered a valid correlation peak. Otherwise, it is determined to be a false or invalid peak, and the search continues backward for the next potential peak.

[0163] In the above embodiment, by introducing the signal-to-noise ratio indicator to verify the correlation peak, the probability of noise-induced false correlation peaks being misjudged as valid is effectively reduced, and by setting the sampling point interval, interference pulses or background noise of different lengths can be flexibly responded to, thereby improving the adaptability to complex channel conditions of the power line.

[0164] As previously mentioned, the power line communication environment is complex, with a large amount of narrowband interference, periodic background noise, and random burst noise present in the channel, which can easily cause false peaks or reduce peak significance, leading to synchronization errors. To this end, further, in step 4444, the signal-to-noise ratio of the maximum correlation peak within the sampling point interval is determined to verify the validity of the maximum correlation peak, including: determining the average autocorrelation result based on the autocorrelation results corresponding to each sampling point in the sampling point interval; determining the signal-to-noise ratio of the peak value of the maximum correlation peak to the average autocorrelation result; and determining that the maximum correlation peak is valid when the signal-to-noise ratio exceeds the signal-to-noise ratio threshold.

[0165] In some embodiments, the signal receiving device selects one or more sampling point intervals adjacent to the maximum correlation peak (eg, a fixed-length interval after the peak sampling point), extracts the autocorrelation results within the intervals, and calculates their average value as the average autocorrelation result.

[0166] The signal receiving device then compares the peak value of the maximum correlation peak with the average autocorrelation result to obtain the signal-to-noise ratio (SNR) of the peak. The SNR characterizes the shape of the maximum correlation peak: a larger SNR indicates a sharper peak, while a smaller SNR indicates a flatter peak.

[0167] If the calculated signal-to-noise ratio exceeds the signal-to-noise ratio threshold, the signal receiving device determines that the maximum correlation peak is valid; otherwise, if the calculated signal-to-noise ratio does not exceed the signal-to-noise ratio threshold, the signal receiving device determines that the maximum correlation peak is invalid.

[0168] Figure 6 Schematic diagram of the shape of the maximum correlation peak provided in some embodiments of the present invention. Figure 6 As shown, Figure 6 (a) indicates that the maximum correlation peak is valid, while Figure 6 (b) indicates that the maximum correlation peak is invalid.

[0169] In the above embodiment, by making a judgment based on the signal-to-noise ratio, it is possible to more accurately evaluate whether the correlation peak is prominent, avoid misjudging the noise-induced pseudo peak as a valid peak, and suppress low-frequency influences such as sudden interference and background clutter, thereby improving synchronization robustness and accuracy.

[0170] In addition, traditional solutions usually use a synchronization strategy that samples a fixed threshold to determine the correlation peak. However, in OFDM systems, especially in high-speed power line communication environments, the presence of strong background noise, narrowband interference, and sudden pulse noise causes large fluctuations in correlation detection results, especially autocorrelation results. This makes traditional methods difficult to adapt to rapidly changing channel conditions and is prone to starting the synchronization process too early or too late.

[0171] To this end, in some embodiments, in step 440, the determining of the maximum correlation peak when the autocorrelation result exceeds the dynamic threshold includes: comparing the current autocorrelation result with the dynamic threshold; when the autocorrelation result exceeds the dynamic threshold, updating the dynamic threshold based on the current autocorrelation result to obtain a new dynamic threshold; the new dynamic threshold is used for comparison with the newly obtained autocorrelation result next time; continuing to receive the signal sequence, and returning to the step of comparing the current autocorrelation result with the dynamic threshold until the current autocorrelation result does not exceed the dynamic threshold obtained by the most recent update, and obtaining the target dynamic threshold; verifying the validity of the target dynamic threshold, and when the target dynamic threshold is valid, determining the current autocorrelation result as the maximum correlation peak.

[0172] In each process of searching for the maximum correlation peak, the signal receiving device first determines the autocorrelation result k1 of the current sampling point a1 and compares it with the initial dynamic threshold λ0. The initial dynamic threshold can be determined based on the actual power line carrier communication channel.

[0173] If the current autocorrelation result k1 exceeds the initial dynamic threshold λ0, the signal receiving device records the current autocorrelation result k1 and updates the initial dynamic threshold λ1 using the current autocorrelation result k1 to obtain a new dynamic threshold λ1. The method of updating the dynamic threshold based on the autocorrelation result includes: using the autocorrelation value of the current autocorrelation result as the new dynamic threshold value.

[0174] At this point, the signal receiving device cannot yet determine whether the current autocorrelation result represents the maximum correlation peak. Therefore, the signal receiving device determines the autocorrelation result k2 for the next sampling point a2 and compares it with the previously updated dynamic threshold λ1. If the current autocorrelation result k2 exceeds the previously updated dynamic threshold λ1, the signal receiving device records the current autocorrelation result k2 and uses it to update the initial dynamic threshold λ1, obtaining a new dynamic threshold λ2. This comparison and updating process is repeated continuously.

[0175] If the autocorrelation result kn of a certain sampling point an does not exceed the dynamic threshold λn-1 obtained by the last update, it means that the current autocorrelation result kn is likely to be a maximum correlation peak. The signal receiving device then uses the dynamic threshold λn-1 obtained by the last update as the target dynamic threshold in the process of searching for the maximum correlation peak this time, and verifies the validity of the target dynamic threshold.

[0176] Due to the complex and ever-changing channel environment, if the autocorrelation value of a sampling point is high, but the autocorrelation results of the immediately adjacent sampling points continue to rise or fluctuate, this indicates that the point is not a peak, but rather an intermediate point in a local rise. In this case, the updated dynamic threshold may still need to be updated. Therefore, verifying the effectiveness of the target dynamic threshold by determining whether the autocorrelation results of subsequent sampling points within a certain range rise compared to the current autocorrelation result, and then determining whether the current autocorrelation result is the maximum correlation peak in the current maximum correlation peak search, can effectively avoid misidentifying interference spikes as the maximum correlation peak.

[0177] When the target dynamic threshold is valid, the signal receiving device determines the current autocorrelation result as the maximum correlation peak. This eliminates the need for single-point judgment and instead relies on statistical judgment across a range of continuous sampling points, effectively suppressing false triggering caused by sudden noise or channel anomalies and improving system robustness.

[0178] The method of updating the initial dynamic threshold based on the autocorrelation result includes, for example: updating the initial dynamic threshold to the absolute value of the autocorrelation value.

[0179] In the above embodiment, a dynamic threshold iterative update mechanism is introduced. By comparing the autocorrelation results with the current dynamic threshold, the threshold level is adaptively adjusted. The maximum correlation peak is determined based on the node at which the update is subsequently stopped. This effectively adapts to channel characteristics under varying signal-to-noise ratios, avoiding the problem of misjudgments or missed detections caused by environmental variations with a fixed threshold. Furthermore, the introduction of a target dynamic threshold verification mechanism further enhances the reliability of correlation peak detection, making synchronization point identification more accurate and improving the robustness and stability of the signal synchronization process.

[0180] Accordingly, in some embodiments, determining the validity of the most recently updated dynamic threshold includes: determining a preset number of target sampling points after the current sampling point, and determining the autocorrelation results corresponding to each target sampling point; the current sampling point corresponds to the current autocorrelation result; and determining that the candidate dynamic threshold is valid if the autocorrelation results corresponding to each target sampling point do not exceed the autocorrelation result corresponding to the current sampling point.

[0181] After identifying a candidate maximum correlation peak, that is, the current autocorrelation result, the signal receiving device needs to further verify the validity of its corresponding dynamic threshold. Specifically, the signal receiving device obtains several sampling points after the current sampling point as target sampling points, and calculates the autocorrelation values of these target sampling points respectively. If the autocorrelation values of all these target sampling points do not exceed the autocorrelation value of the current sampling point, it can be confirmed that the candidate correlation peak has a local maximum and the dynamic threshold is representative, so it can be used as a valid target dynamic threshold, and then the autocorrelation result corresponding to the sampling point is determined to be the maximum correlation peak. In this way, the accuracy of the maximum correlation peak determination in the actual power line carrier communication environment can be effectively improved.

[0182] The preset number may be, for example, 20 to 50 sampling points, and the specific value may be determined based on actual communication conditions.

[0183] In the above embodiment, by introducing a dynamic threshold verification mechanism for subsequent sampling points, it is confirmed that the sampling point corresponding to the target dynamic threshold is indeed the local maximum correlation peak, effectively suppressing the false peak judgment caused by sudden interference or local noise, thereby improving the accuracy of signal synchronization and avoiding synchronization position drift.

[0184] In complex noise environments or multipath interference, single correlation peak detection is prone to occasional peaks, false peaks, or missed peaks, leading to synchronization misjudgment. Therefore, a single detected valid correlation peak is not sufficient to confirm the synchronization status.

[0185] To this end, in some embodiments, between step 440 and step 460, the power line carrier signal synchronization method provided by the present invention also includes step 450: determining a historical effective correlation peak, and determining a first spacing between the historical effective correlation peak and the current effective correlation peak; when the first spacing meets the spacing threshold condition, increasing the adjacent count value; when the first spacing does not meet the spacing threshold condition, resetting the adjacent count value; when the adjacent count value exceeds the preset counting threshold, determining that the effective correlation peak and the historical effective correlation peak constitute a continuous correlation peak.

[0186] In this embodiment, after detecting the current valid correlation peak, the signal receiving device determines whether the spacing threshold condition is met based on the sampling point spacing between the current valid correlation peak and the historical valid correlation peak, which is called the first spacing.

[0187] The first interval is generally consistent with the length of a known synchronization sequence (such as SYNCP), and an allowable error range may be preset to constitute an interval threshold condition.

[0188] If the first interval meets the interval threshold condition, that is, the first interval does not exceed the interval threshold, the signal receiving device considers that the current correlation peak is associated with the historical correlation peak and may be a continuous synchronization mark; otherwise, it is considered that there is loss or interference in the middle.

[0189] In addition, the signal receiving device also maintains an adjacent count value to record the number of times the continuous spacing meets the conditions: if the current spacing meets the conditions, the adjacent count value is incremented; if the current spacing does not meet the conditions, the count value is reset; when the adjacent count value exceeds the set counting threshold, it can be determined that multiple consecutive valid correlation peaks have been detected, and it can be confirmed that the synchronization state has been entered.

[0190] For example, assuming the locally known synchronization sequence SYNCP is 1024 points long and has a preset tolerance of ±20 points, the spacing threshold condition defines a spacing threshold range of [1004, 1044]. The signal receiving device first detects a valid correlation peak A and records its peak position as sampling point P1 = 2048. Subsequently, a valid correlation peak B is detected at P2 = 3075, with a spacing of 1027 points between the two, which is within the tolerance. The adjacent count value, Begincount++, increases from an initial value of 1 (begincount+, which increases from 0 to 1 upon detection of the current valid correlation peak) to 2. If a valid correlation peak C is subsequently detected at sampling point P3 = 4099, with a spacing of 1024 points between the peak and B, the adjacent count value increases to 3. Once the preset counting threshold (e.g., 3 times) is reached, the signal receiving device determines that A, B, and C are consecutive correlation peaks and enters the frame synchronization state, i.e., the SYNCBegin state. If a certain interval is 980 or 1060, which does not meet the range [1004, 1044], the adjacent count values are cleared to avoid misjudgment.

[0191] In the above embodiment, the continuous peak judgment mechanism is used to effectively distinguish accidental noise peaks from real synchronization peaks, and can avoid the system entering synchronization prematurely due to a single false peak or misjudged peak, thereby improving the judgment accuracy and reducing the synchronization failure rate; in addition, the introduction of spacing tolerance and continuous counting mechanism allows a certain degree of synchronization deviation, thereby improving the adaptability to channel disturbances.

[0192] Typically, frame synchronization is achieved by detecting the synchronization sequence and flag sequence pre-embedded in the frame preamble signal. During the frame synchronization process, the receiver must not only determine whether it has entered the synchronization state, but also accurately determine when the synchronization has ended.

[0193] To this end, in some embodiments, in step 460, the signal synchronization step includes steps 462 to 466:

[0194] Step 462: Receive a frame preamble signal; the frame preamble signal includes a synchronization sequence and a flag sequence;

[0195] Step 464: Whenever a valid correlation peak is determined based on the received synchronization sequence, a signal conversion process is performed on the received synchronization sequence to obtain a signal conversion result; the signal conversion result is used for channel estimation;

[0196] Step 466: When it is determined that the flag sequence is received, signal synchronization is ended.

[0197] In this embodiment, when the signal receiving device detects multiple consecutive valid correlation peaks, it determines that it has entered the synchronization state. The signal receiving device receives and buffers the frame preamble signal, which consists of one or more synchronization sequences SYNCP and a flag sequence SYNCM.

[0198] Each time a new significant correlation peak is detected, the signal receiving device performs a signal transformation, such as a Fast Fourier Transform (FFT), on the corresponding synchronization sequence. This transform generates a frequency domain result, which is used to construct a channel estimate. To suppress instantaneous fluctuations, multiple FFT results can be averaged.

[0199] When the signal receiving device detects the flag sequence SYNCM (such as a negative peak in the autocorrelation result or a matching flag bit pattern), it confirms the end of the frame preamble and the frame synchronization process is completed.

[0200] In the above embodiment, the signal synchronization process is executed by the signal receiving device, and the transformation process is triggered by the synchronization sequence, and the flag sequence confirms the exit of the synchronization process, thereby realizing a stable and reliable synchronization start and exit mechanism and providing high-quality input for channel estimation.

[0201] The frame structure is often designed to have distinct characteristics between the flag sequence and the synchronization sequence, such as polarity reversal. By analyzing whether the autocorrelation result changes from a positive peak to a negative value, it can be determined whether SYNCM has been received. This allows for reliable termination of the synchronization process without requiring a full pattern match on the SYNCM.

[0202] To this end, in some embodiments, before step 466, step 465 is also included: when the autocorrelation value is determined to be negative based on the autocorrelation result corresponding to any valid correlation peak, it is determined that a flag sequence is received; wherein the boundary position between the synchronization sequence and the flag sequence is the end position of the signal synchronization.

[0203] In this embodiment, the signal receiving device obtains the autocorrelation result corresponding to the currently detected valid correlation peak. If the autocorrelation result is negative, it is determined that the current input signal contains the marker sequence SYNCM, indicating the end of the frame preamble. Furthermore, this point is used as the intersection of the synchronization sequence SYNCP and the marker sequence SYNCM, and is determined as the end position of frame synchronization.

[0204] In the above embodiment, by analyzing the symbol transition of the autocorrelation result, closed-loop control of the synchronization process is achieved without the need to specifically mark the frame tail structure. Compared with matching the flag sequence or performing continuous cross-correlation operations, determining the symbol of the autocorrelation value is more efficient and more real-time.

[0205] In combination with one or more of the above embodiments, a specific embodiment is described below.

[0206] Figure 7 FIG. 1 is a flow chart of a power line carrier signal synchronization method provided in other embodiments of the present invention. Figure 7 As shown, in some embodiments, the power line carrier signal synchronization method provided by the present invention includes the following steps:

[0207] Step a: Signal detection phase: monitoring the power line channel and determining whether a signal sequence is detected.

[0208] The signal receiving device monitors the power line channel and determines whether a signal sequence containing synchronization information is detected. For example, the signal receiving device may continuously monitor the signal amplitude or power level in the power line channel and compare it with a preset noise threshold to determine whether a possible signal sequence is detected.

[0209] Step b, autocorrelation result calculation stage: when a signal sequence is received, an autocorrelation result is determined based on a known signal sequence.

[0210] Upon receiving a signal sequence, the signal receiving device determines a sign coefficient corresponding to each sampling point based on the signal amplitude corresponding to each sampling point in the signal sequence; wherein the sign of the signal amplitude is consistent with the sign of the sign coefficient; a sign sequence corresponding to the signal sequence is determined based on the sign coefficient corresponding to each sampling point; for any sampling point, the sign coefficient corresponding to the sampling point is multiplied by the known signal at the same position in the known signal sequence to obtain a cross-correlation value corresponding to the sampling point; a cross-correlation result is obtained based on the sum of the cross-correlation values corresponding to each sampling point in the signal sequence. Furthermore, the signal receiving device determines a target historical cross-correlation result, multiplies the cross-correlation result by the target historical cross-correlation result to obtain an autocorrelation value; and an autocorrelation result is obtained based on the absolute value of the autocorrelation value.

[0211] Exemplarily, the signal receiving device uses a sliding window with a length of 1024 to select the received signal data, and performs symbol cross-correlation on the signal in the sliding window with the local SYNCP sequence, that is, only the symbol coefficient is taken without performing a specific amplitude multiplication operation, so as to reduce computing resource consumption and improve computing efficiency.

[0212] After calculating the cross-correlation result, the signal receiving device stores the cross-correlation result in a buffer. Each time a new cross-correlation value is obtained, it is autocorrelated with the cross-correlation value before the 1024th point to obtain the autocorrelation result AutoCorrVal and take the absolute value AbsAutoCorr.

[0213] Therefore, autocorrelation is performed on the basis of the mutual correlation value, that is, by accumulating two mutual correlation values at a preset interval, a more obvious correlation peak can be obtained.

[0214] Step c: Initialize the dynamic threshold.

[0215] Each time the signal receiving device searches for the maximum correlation peak, it first initializes the dynamic threshold, that is, determines the dynamic threshold to be a preset value.

[0216] Step d: Dynamic threshold updating mechanism and effective correlation peak detection stage.

[0217] The signal receiving device compares the obtained autocorrelation result with the dynamic threshold; when the autocorrelation result exceeds the dynamic threshold, the dynamic threshold is updated based on the current autocorrelation result to obtain a new dynamic threshold; the new dynamic threshold is used for comparison with the newly obtained autocorrelation result next time; the signal sequence continues to be received, and the process returns to the first step to continue until the dynamic threshold remains stable, thereby obtaining a dynamic threshold.

[0218] When the absolute autocorrelation value, AbsAutoCorr, is greater than the set dynamic threshold, it indicates that the detected data has a high correlation with the local sequence. However, since the correlation peak has an upward trend, it is necessary to continue searching for the location of the maximum correlation peak. Therefore, each time the signal receiving device obtains a larger AbsAutoCorr value, it uses this value to update the dynamic threshold and continues searching backward until it stops increasing. The dynamic threshold obtained from the last update is used as the target dynamic threshold, and a preset number of target sampling points and autocorrelation results after the current sampling point are determined. If the autocorrelation results corresponding to each target sampling point do not exceed the autocorrelation result corresponding to the current sampling point, the target dynamic threshold is determined to be valid, and the current autocorrelation result is determined to be the maximum correlation peak. The signal receiving device then records the location and the current absolute autocorrelation value to record the maximum correlation peak.

[0219] The signal receiving device then verifies the validity of the maximum correlation peak. The signal receiving device determines the sampling point interval associated with the maximum correlation peak; the sampling point interval does not include the sampling point corresponding to the peak value of the maximum correlation peak. Based on the autocorrelation results corresponding to each sampling point in the sampling point interval, the signal receiving device determines an average autocorrelation result. Furthermore, the signal receiving device determines the signal-to-noise ratio between the peak value of the maximum correlation peak and the average autocorrelation result; if the signal-to-noise ratio exceeds a signal-to-noise ratio threshold, the maximum correlation peak is determined to be valid.

[0220] For example, after finding the location of the maximum correlation peak, the signal receiving device skips back 20 points and then calculates the average absolute autocorrelation value of 1000 points as background noise. The signal-to-noise ratio (SNR) is calculated as the ratio of the maximum peak autocorrelation value to the average absolute autocorrelation value of that segment. If the SNR is greater than the set SNR threshold, the correlation peak is considered valid and the adjacent count value Begincount = 1.

[0221] Step e: Continuous correlation peak judgment stage.

[0222] The signal receiving device determines a historical valid correlation peak and a first spacing between the historical valid correlation peak and the current valid correlation peak. If the first spacing meets a spacing threshold, the device increments an adjacent count value. If the first spacing does not meet the spacing threshold, the device resets the adjacent count value. If the adjacent count value exceeds a preset count threshold, the device determines that the valid correlation peak and the historical valid correlation peak constitute a continuous correlation peak. If the adjacent count value exceeds the preset count threshold, indicating that the number of continuous correlation peaks exceeds a preset threshold, the signal receiving device confirms that the signal synchronization opportunity has been met.

[0223] For example, the signal receiving device repeats steps a to e, finds the next correlation peak, and determines whether the distance between the correlation peak position and the previous correlation peak is within the range of 1024±20. If it is within the range, it means that continuous correlation peaks have been found, and Begincount++ is set. If it is not within the range, it means that SYNCP is missed in the middle, and Begincount is reset to 1.

[0224] Step f: Signal synchronization and channel estimation stage: When the effective correlation peak and the historical effective correlation peak constitute a continuous correlation peak, signal synchronization is started.

[0225] When the effective correlation peak and the historical effective correlation peak form a continuous correlation peak, the signal receiving device receives a frame preamble signal; the frame preamble signal includes a synchronization sequence and a flag sequence. Whenever an effective correlation peak is determined based on the received synchronization sequence, the signal receiving device performs signal transformation processing on the received synchronization sequence to obtain a signal transformation result; the signal transformation result is used for channel estimation.

[0226] For example, when BeginCount > 2, indicating that three consecutive valid correlation peaks have been found, the signal receiving device enters the SYNCBegin state and continues searching for correlation peaks. Each time a correlation peak is found, the signal receiving device performs an FFT on the input signal at the corresponding position, averages the result with the previous FFT, and saves the FFT result for subsequent channel estimation.

[0227] Step g: Flag sequence detection stage: When the autocorrelation value is determined to be negative based on the autocorrelation result corresponding to any valid correlation peak, the signal receiving device determines that the flag sequence has been received; wherein the boundary position between the synchronization sequence and the flag sequence is the end position of the signal synchronization.

[0228] For example, when the signal receiving device finds a correlation peak and the autocorrelation result AutoCorrVal is a negative number, it means that the position of SYNCM has been found. The signal receiving device no longer performs FFT operation and uses the position of the intersection of SYNCP and SYNCM as the final positioning position of the frame synchronization for subsequent acquisition of frame control data and data payload.

[0229] When the flag sequence is successfully detected, the signal receiving device ends the signal synchronization process, completes the synchronization positioning of the frame structure, and provides data support for subsequent data analysis.

[0230] To verify the robustness and detection accuracy of the proposed power line carrier signal synchronization method under different channel conditions, simulation experiments were conducted. Specifically, the cross-correlation results between the input signal and the known synchronization sequence, as well as the further calculated autocorrelation results, were analyzed and compared under noise-free conditions and a low signal-to-noise ratio of -10 dB.

[0231] The following will be presented separately in combination with simulation data diagrams.

[0232] Figure 8 1 is a schematic diagram of a cross-correlation result obtained after a cross-correlation operation is performed between a signal sequence and a known synchronization sequence under noise-free conditions provided in some embodiments of the present invention. Figure 8 The figure shows the cross-correlation result obtained after the signal sequence and the known synchronization sequence are cross-correlated under noise-free conditions. Figure 8 As shown in the figure, under ideal channel conditions (i.e., noise-free conditions), after cross-correlating the received signal sequence with the locally known synchronization sequence SYNCP, the resulting cross-correlation result, CorrVal, exhibits a significant sharp peak, clearly locating the synchronization point. This correlation peak has an extremely high amplitude relative to the surrounding background noise, demonstrating that traditional cross-correlation methods can achieve relatively ideal synchronization detection results in the absence of interference.

[0233] Figure 9 1 is a schematic diagram of autocorrelation results obtained after performing autocorrelation calculation based on cross-correlation results under noise-free conditions provided in some embodiments of the present invention. Figure 9 The figure shows the autocorrelation result obtained after further autocorrelation processing on this basis. Figure 9 As shown in the figure, after the autocorrelation operation, the autocorrelation value autoCorr of the maximum correlation peak remains highly concentrated and sharp, and its corresponding absolute value is much higher than the rest of the background, which can further enhance the ability to confirm the location of the correlation peak. This shows that in noise-free conditions, the introduction of autocorrelation calculation can enhance the characteristics of the correlation peak and improve the accuracy of synchronous positioning, providing a more reliable data foundation for subsequent synchronization confirmation and dynamic threshold setting.

[0234] Figure 10 FIG. 1 is a schematic diagram of a cross-correlation result obtained after performing a cross-correlation operation between a signal sequence and a known synchronization sequence under noise interference provided in some embodiments of the present invention. Figure 10 Figure 2 shows the cross-correlation results obtained when there is high noise interference in the channel. Figure 10As shown in the figure, under power line channel conditions with a low signal-to-noise ratio (SNR = -10dB) and the presence of sudden interference, the main correlation peak in the cross-correlation result CorrVal still exists, but its relative amplitude decreases significantly, making it less distinguishable from the multiple surrounding false peaks. Furthermore, background noise causes significant perturbations in the overall cross-correlation plot, making it prone to misjudgment of synchronization positions. This demonstrates the limited robustness of traditional cross-correlation-based synchronization detection methods under low signal-to-noise ratio conditions.

[0235] Figure 11 FIG. 1 is a schematic diagram of autocorrelation results obtained after performing autocorrelation calculation based on cross-correlation results under noise interference conditions provided in some embodiments of the present invention. Figure 11 Figure 2 shows the autocorrelation result obtained after autocorrelation processing based on the cross-correlation result when there is high noise interference in the channel. Figure 11 As shown in the figure, under the same low signal-to-noise ratio condition (SNR=-10dB), after performing autocorrelation processing based on the cross-correlation results, the autocorrelation value autoCorr significantly improves the relative prominence of the main correlation peak. Although channel interference still exists, the absolute value of the autocorrelation value shows higher concentration and discriminability at the main peak position, compared with Figure 10 The autocorrelation processing effectively suppresses the interference peaks mixed in the signal and enhances the recognition ability of the effective correlation peaks. Combined with the dynamic threshold update mechanism and the peak shape evaluation method, the accuracy and robustness of synchronization recognition can be further improved.

[0236] Through the above comparison, it can be more intuitively observed that the method proposed in the present invention can still effectively extract correlation peaks, adapt dynamic thresholds and identify synchronization starting points in the presence of channel noise, thereby achieving robust signal synchronization.

[0237] The power line carrier signal synchronization method provided in the embodiment of the present invention can be executed by a power line carrier signal synchronization device. In the embodiment of the present invention, the power line carrier signal synchronization device performing the power line carrier signal synchronization method is used as an example to illustrate the power line carrier signal synchronization device provided in the embodiment of the present invention.

[0238] Figure 12 Schematic diagram of the structure of the power line carrier signal synchronization device provided in some embodiments of the present invention. Figure 12 As shown, an embodiment of the present invention further provides a power line carrier signal synchronization device, which is applied to a signal receiving device. The power line carrier signal synchronization device includes an operation module 1201, a processing module 1202 and a synchronization module 1203. In which:

[0239] The operation module 1201 is configured to determine an autocorrelation result based on a known signal sequence when a signal sequence is received.

[0240] The processing module 1202 is configured to determine a valid correlation peak when the autocorrelation result exceeds a dynamic threshold value; the dynamic threshold value is dynamically updated according to the changing trend of the multiple autocorrelation results.

[0241] The synchronization module 1203 is configured to start signal synchronization when the effective correlation peak and the historical effective correlation peak constitute continuous correlation peaks.

[0242] According to the power line carrier signal synchronization device provided by the embodiment of the present invention, by detecting the signal sequence and, when the signal sequence is received, determining the autocorrelation result based on the known signal sequence, the synchronization features in the signal can be effectively detected through autocorrelation processing, thereby improving the accuracy and reliability of the synchronization detection; when the autocorrelation result exceeds the dynamic threshold, the effective correlation peak is determined, and the invalid correlation peak can be eliminated, thereby improving the anti-interference ability of the synchronization detection, and a dynamic threshold mechanism based on the changing trend of the autocorrelation result is adopted, which can adaptively update the threshold, making the identification of the effective correlation peak more accurate; and when the effective correlation peak and the historical effective correlation peak constitute a continuous correlation peak, by detecting the continuous correlation peak, the stability and consistency of the synchronization signal are ensured, thereby reliably starting the signal synchronization process, reducing the possibility of misjudgment and missed judgment, realizing efficient and accurate synchronization of the signal in a complex channel environment, and enhancing the robustness and reliability of the signal synchronization.

[0243] According to one embodiment of the present invention, the processing module is also used to determine the maximum correlation peak when the autocorrelation result exceeds the dynamic threshold; the peak value of the maximum correlation peak is the current autocorrelation result, and the peak position is the signal position of the sampling point corresponding to the peak; verify the validity of the maximum correlation peak, and when the validity verification passes, determine the maximum correlation peak as a valid correlation peak.

[0244] According to one embodiment of the present invention, the processing module is also used to determine the sampling point interval associated with the maximum correlation peak; the sampling point interval does not include the sampling point corresponding to the peak value of the maximum correlation peak; and determine the signal-to-noise ratio of the maximum correlation peak in the sampling point interval to verify the validity of the maximum correlation peak.

[0245] According to one embodiment of the present invention, the processing module is further used to determine an average autocorrelation result based on the autocorrelation results corresponding to each sampling point in the sampling point interval; determine the signal-to-noise ratio of the peak value of the maximum correlation peak to the average autocorrelation result; wherein the signal-to-noise ratio characterizes the shape of the maximum correlation peak, and the larger the signal-to-noise ratio, the sharper the maximum correlation peak; when the signal-to-noise ratio exceeds the signal-to-noise ratio threshold, the maximum correlation peak is determined to be valid.

[0246] According to one embodiment of the present invention, the above-mentioned device also includes a threshold module, which is used to compare the current autocorrelation result with a dynamic threshold; when the autocorrelation result exceeds the dynamic threshold, the dynamic threshold is updated based on the current autocorrelation result to obtain a new dynamic threshold; the new dynamic threshold is used to compare with the newly obtained autocorrelation result next time; continue to receive the signal sequence, and return to the step of comparing the current autocorrelation result with the dynamic threshold to continue executing until the current autocorrelation result does not exceed the dynamic threshold obtained by the most recent update, and obtain the target dynamic threshold; verify the validity of the target dynamic threshold, and when the target dynamic threshold is valid, determine the current autocorrelation result as the maximum correlation peak.

[0247] According to one embodiment of the present invention, the threshold module is further configured to determine a preset number of target sampling points after the current sampling point, and respectively determine an autocorrelation result corresponding to each target sampling point; the current sampling point corresponds to the current autocorrelation result; and when the autocorrelation results corresponding to each target sampling point do not exceed the autocorrelation result corresponding to the current sampling point, determining that the target dynamic threshold is valid.

[0248] According to one embodiment of the present invention, the above-mentioned device also includes a judgment module, which is used to determine a historical valid correlation peak and determine a first distance between the historical valid correlation peak and the current valid correlation peak; when the first distance meets the distance threshold condition, increase the adjacent count value; when the first distance does not meet the distance threshold condition, reset the adjacent count value; when the adjacent count value exceeds the preset count threshold, determine that the valid correlation peak and the historical valid correlation peak constitute a continuous correlation peak.

[0249] According to one embodiment of the present invention, the operation module is further used to perform a cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result; determine a target historical cross-correlation result; and perform an autocorrelation operation on the cross-correlation result and the target historical cross-correlation result to obtain an autocorrelation result.

[0250] According to one embodiment of the present invention, the operation module is further used to determine the symbol coefficient corresponding to each sampling point based on the signal amplitude corresponding to each sampling point in the signal sequence; wherein the positive and negative signs of the signal amplitude are consistent with the positive and negative signs of the symbol coefficient; based on the symbol coefficient corresponding to each sampling point, determine the symbol sequence corresponding to the signal sequence; perform a cross-correlation operation on the symbol sequence and the known signal sequence to obtain a cross-correlation result.

[0251] According to one embodiment of the present invention, the operation module is further used to multiply the symbol coefficient corresponding to any sampling point by the known signal at the same position in the known signal sequence to obtain the cross-correlation value corresponding to the sampling point; and obtain the cross-correlation result based on the sum of the cross-correlation values corresponding to each sampling point in the signal sequence.

[0252] According to one embodiment of the present invention, the operation module is further configured to multiply the cross-correlation result by the target historical cross-correlation result to obtain an autocorrelation value; and obtain the autocorrelation result based on the absolute value of the autocorrelation value.

[0253] According to one embodiment of the present invention, there is a second interval between the target history cross-correlation result and the cross-correlation result, and the length of the second interval is the same as the length of the known signal sequence.

[0254] According to one embodiment of the present invention, the synchronization module is also used to receive a frame preamble signal; the frame preamble signal includes a synchronization sequence and a flag sequence; whenever a valid correlation peak is determined based on the received synchronization sequence, the received synchronization sequence is subjected to signal conversion processing to obtain a signal conversion result; the signal conversion result is used for channel estimation; when it is determined that the flag sequence is received, the signal synchronization is ended.

[0255] According to one embodiment of the present invention, the synchronization module is further used to determine that a flag sequence is received when the autocorrelation value is determined to be negative based on the autocorrelation result corresponding to any valid correlation peak; wherein the boundary position between the synchronization sequence and the flag sequence is the end position of the signal synchronization.

[0256] According to one embodiment of the present invention, the sequence length of the signal sequence is the same as the sequence length of the known signal sequence, and the known signal sequence corresponds to the synchronization sequence.

[0257] The power line carrier signal synchronization device in the embodiments of the present invention is applied to a signal receiving device. The signal receiving device can be a computer device or a component of the computer device, such as an integrated circuit or chip. The computer device can be a terminal device, etc. For example, the computer device can be a mobile phone, tablet computer, laptop computer, PDA, in-vehicle computer device, mobile internet device (MID), augmented reality (AR) / virtual reality (VR) device, robot, wearable device, ultra-mobile personal computer (UMPC), netbook, or personal digital assistant (PDA). The computer device can also be a server, network attached storage (NAS), personal computer (PC), television, ATM, or self-service machine, etc., and the embodiments of the present invention do not specifically limit this.

[0258] The power line carrier signal synchronization device in the embodiment of the present invention may be a device having an operating system. The operating system may be a Microsoft (Windows) operating system, an Android operating system, an iOS operating system, or other possible operating systems, which are not specifically limited in the embodiment of the present invention.

[0259] The power line carrier signal synchronization device provided in the embodiment of the present invention can implement each process implemented in each method embodiment, and to avoid repetition, it will not be described again here.

[0260] Figure 13 Schematic diagram of the structure of a computer device provided in some embodiments of the present invention. Figure 13 As shown, an embodiment of the present invention further provides a computer device 1300, including a processor 1301, a memory 1302, and a computer program stored in the memory 1302 and executable on the processor 1301. When the program is executed by the processor 1301, the various processes of the above-mentioned method embodiments are implemented, and the same technical effects can be achieved. To avoid repetition, they will not be described here.

[0261] It should be noted that the computer devices in the embodiments of the present invention include the mobile computer devices and non-mobile computer devices mentioned above.

[0262] An embodiment of the present invention also provides a non-transitory computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the various processes of the above-mentioned power line carrier signal synchronization method embodiment and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0263] The processor is the processor in the computer device described in the above embodiment. The readable storage medium includes a computer readable storage medium, such as a computer read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0264] An embodiment of the present invention further provides a computer program product, including a computer program, which implements the above-mentioned power line carrier signal synchronization method when executed by a processor.

[0265] The processor is the processor in the computer device described in the above embodiment. The readable storage medium includes a computer readable storage medium, such as a computer read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0266] An embodiment of the present invention further provides a chip, which includes a processor and a communication interface, the communication interface is coupled to the processor, and the processor is used to run programs or instructions to implement the various processes of the above-mentioned power line carrier signal synchronization method embodiment, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0267] It should be understood that the chip mentioned in the embodiment of the present invention can also be called a system-on-chip, a system-on-chip, a chip system, or a system-on-chip chip, etc.

[0268] It should be noted that, in this article, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present invention is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in the opposite order according to the functions involved. For example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0269] Through the above description of the embodiments, those skilled in the art will clearly understand that the methods of the above embodiments can be implemented using software plus the necessary general-purpose hardware platform. Of course, hardware can also be used, but in many cases the former is a more preferred implementation method. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the relevant art, can be embodied in the form of a computer software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, or optical disk) and includes a number of instructions for enabling a terminal (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in various embodiments of the present invention.

[0270] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

[0271] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0272] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0273] Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0274] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, "the method includes steps (a) and (b)" means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, "the method may further include step (c)" means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0275] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for synchronizing a power line carrier signal, characterized in that: The method comprises: In the case of receiving the signal sequence, determining an autocorrelation result based on the known signal sequence; When the autocorrelation result exceeds a dynamic threshold, determining a valid correlation peak; the dynamic threshold starts from an initial dynamic threshold and is dynamically updated along with the changing trend of the multiple autocorrelation results until the dynamic threshold reaches a maximum value; In the case where the effective correlation peak and the historical effective correlation peak form a continuous correlation peak, starting signal synchronization; Wherein, when the autocorrelation result exceeds the dynamic threshold, determining the effective correlation peak includes: When the autocorrelation result exceeds the dynamic threshold, a maximum correlation peak is determined; the peak value of the maximum correlation peak is the current autocorrelation result, and the peak position is the signal position of the sampling point corresponding to the peak value; Verifying the validity of the maximum correlation peak, and if the validity verification passes, determining the maximum correlation peak as a valid correlation peak; The verification of the validity of the maximum correlation peak includes: Determining a sampling point interval associated with a maximum correlation peak; wherein the sampling point interval does not include a sampling point corresponding to a peak value of the maximum correlation peak; Determine the signal-to-noise ratio of the maximum correlation peak within the sampling point interval to verify the validity of the maximum correlation peak; The step of determining the signal-to-noise ratio of the maximum correlation peak within the sampling point interval to verify the validity of the maximum correlation peak includes: Determine an average autocorrelation result based on the autocorrelation results corresponding to each sampling point in the sampling point interval; Determining a signal-to-noise ratio between the peak value of the maximum correlation peak and the average autocorrelation result; wherein the signal-to-noise ratio characterizes the shape of the maximum correlation peak, and the larger the signal-to-noise ratio, the sharper the maximum correlation peak; When the signal-to-noise ratio exceeds the signal-to-noise ratio threshold, the maximum correlation peak is determined to be valid.

2. The power line carrier signal synchronization method according to claim 1, characterized in that: The step of determining the maximum correlation peak when the autocorrelation result exceeds the dynamic threshold comprises: Compare the current autocorrelation result with the dynamic threshold; When the autocorrelation result exceeds the dynamic threshold, the dynamic threshold is updated based on the current autocorrelation result to obtain a new dynamic threshold; the new dynamic threshold is used for comparison with the newly obtained autocorrelation result next time; Continue receiving the signal sequence and return to the step of comparing the current autocorrelation result with the dynamic threshold until the current autocorrelation result does not exceed the dynamic threshold obtained by the most recent update, thereby obtaining a target dynamic threshold; The validity of the target dynamic threshold is verified, and when the target dynamic threshold is valid, the current autocorrelation result is determined as the maximum correlation peak.

3. The power line carrier signal synchronization method according to claim 2, characterized in that: Verifying the validity of the target dynamic threshold includes: Determine a preset number of target sampling points after the current sampling point, and respectively determine the autocorrelation results corresponding to each target sampling point; the current sampling point corresponds to the current autocorrelation result; In a case where the autocorrelation results corresponding to each target sampling point do not exceed the autocorrelation result corresponding to the current sampling point, it is determined that the target dynamic threshold is valid.

4. The power line carrier signal synchronization method according to claim 1, characterized in that: After determining the effective correlation peak, and when the effective correlation peak and the historical effective correlation peak form a continuous correlation peak, before initiating signal synchronization, the method further includes: Determining a historical effective correlation peak, and determining a first distance between the historical effective correlation peak and a current effective correlation peak; When the first distance satisfies the distance threshold condition, the adjacent count value is increased; When the first distance does not meet the distance threshold condition, resetting the adjacent count value; When the adjacent count values exceed a preset count threshold, it is determined that the effective correlation peak and the historical effective correlation peak constitute a continuous correlation peak.

5. The power line carrier signal synchronization method according to claim 1, characterized in that: The step of determining an autocorrelation result based on a known signal sequence when a signal sequence is received includes: Performing a cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result; Determine target historical cross-correlation results; An autocorrelation operation is performed on the cross-correlation result and the target historical cross-correlation result to obtain an autocorrelation result.

6. The power line carrier signal synchronization method according to claim 5, characterized in that: The performing a cross-correlation operation on the signal sequence and the known signal sequence to obtain a cross-correlation result includes: Determining a sign coefficient corresponding to each sampling point based on a signal amplitude corresponding to each sampling point in the signal sequence; wherein the sign of the signal amplitude is consistent with the sign of the sign coefficient; Determining a symbol sequence corresponding to the signal sequence based on the symbol coefficients corresponding to each sampling point; Perform a cross-correlation operation on the symbol sequence and the known signal sequence to obtain a cross-correlation result.

7. A power line carrier signal synchronization device, characterized in that: The device comprises: an operation module, configured to determine an autocorrelation result based on a known signal sequence when a signal sequence is received; a processing module, configured to determine a valid correlation peak when the autocorrelation result exceeds a dynamic threshold; the dynamic threshold starting from an initial dynamic threshold and dynamically updated along with the changing trend of the plurality of autocorrelation results until the dynamic threshold reaches a maximum value; A synchronization module, configured to start signal synchronization when the effective correlation peak and the historical effective correlation peak form a continuous correlation peak; Wherein, when the autocorrelation result exceeds the dynamic threshold, determining the effective correlation peak includes: When the autocorrelation result exceeds the dynamic threshold, a maximum correlation peak is determined; the peak value of the maximum correlation peak is the current autocorrelation result, and the peak position is the signal position of the sampling point corresponding to the peak value; Verifying the validity of the maximum correlation peak, and if the validity verification passes, determining the maximum correlation peak as a valid correlation peak; The verification of the validity of the maximum correlation peak includes: Determining a sampling point interval associated with a maximum correlation peak; wherein the sampling point interval does not include a sampling point corresponding to a peak value of the maximum correlation peak; Determine the signal-to-noise ratio of the maximum correlation peak within the sampling point interval to verify the validity of the maximum correlation peak; The step of determining the signal-to-noise ratio of the maximum correlation peak within the sampling point interval to verify the validity of the maximum correlation peak includes: Determine an average autocorrelation result based on the autocorrelation results corresponding to each sampling point in the sampling point interval; Determining a signal-to-noise ratio between the peak value of the maximum correlation peak and the average autocorrelation result; wherein the signal-to-noise ratio characterizes the shape of the maximum correlation peak, and the larger the signal-to-noise ratio, the sharper the maximum correlation peak; When the signal-to-noise ratio exceeds the signal-to-noise ratio threshold, the maximum correlation peak is determined to be valid.

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