Frame synchronization method and device based on soft information filtering and phase ambiguity resolution

Abstract

This application discloses a frame synchronization method and device based on soft information filtering and phase ambiguity resolution. By utilizing demodulated soft information for frame synchronization and incorporating novel strategies such as soft information filtering, phase ambiguity resolution, Doppler frequency estimation and compensation, dynamic frame header adjustment, multi-frame joint detection, and adaptive decision thresholding, the accuracy and robustness of frame synchronization are significantly improved. The method is suitable for handling frame synchronization issues with long frame headers in low signal-to-noise ratio environments and effectively resolves phase ambiguity issues in situations with large Doppler frequency variations.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a frame synchronization method and device based on soft information filtering and phase ambiguity resolution. Background Art

[0002] In digital communication systems, frame synchronization is a critical step in ensuring that the receiving end can correctly identify and extract data frames. Traditional frame synchronization methods are usually based on hard decisions, that is, matching the received data with the predefined frame header by comparing it bit by bit. However, in low signal-to-noise ratio environments (below 0dB), traditional frame synchronization methods are prone to misjudgment, resulting in frame synchronization failure or increased bit error rate. In addition, when the frame header length is long (such as 96 bits), traditional frame synchronization methods have high computational complexity and are more sensitive to outliers (such as burst noise), which can easily lead to missed alarms or false alarms. Another common problem is phase ambiguity, that is, the receiving end cannot determine the absolute phase of the received signal, resulting in frame synchronization failure or data demodulation errors.

[0003] In environments with high Doppler frequency variations (such as high-speed mobile communications and satellite communications), the received signal frequency changes rapidly over time, making it difficult for traditional frame synchronization methods to effectively track signal changes, further increasing the difficulty of frame synchronization. Therefore, achieving reliable frame synchronization in environments with high Doppler frequency variations has become a major challenge in current communication systems. Summary of the Invention

[0004] Based on this, an embodiment of the present application provides a frame synchronization method and device based on soft information filtering and phase ambiguity resolution. This method uses the demodulated soft information (LLR, Log-Likelihood Ratio) for frame synchronization and combines it with phase ambiguity resolution technology. It is particularly suitable for processing frame synchronization problems of long frame headers (such as 96 bits) in a low signal-to-noise ratio (below 0dB) environment. In addition, it improves the accuracy and robustness of frame synchronization when the Doppler frequency change rate is large, reduces the probability of missed alarms and false alarms, and solves the phase ambiguity problem at the same time.

[0005] In a first aspect, a frame synchronization method based on soft information filtering and phase ambiguity resolution is provided, the method comprising:

[0006] The receiving end receives the signal, demodulates it, and outputs soft information;

[0007] Filtering the soft information and removing bad values, and smoothing the retained soft information; wherein the smoothing is achieved by sliding window averaging or weighted averaging;

[0008] Match the filtered soft information with the predefined frame header and calculate the matching result. For long frame headers, segment matching and parallel processing are used, and the matching result is obtained by weighted summation.

[0009] Determine whether synchronization is successful based on the matching result and the preset decision threshold;

[0010] When frame synchronization is successful, a frame synchronization signal is output.

[0011] Optionally, the method further includes:

[0012] Manage the frame synchronization status and control the switching between initial synchronization, formal synchronization and out-of-sync status;

[0013] Dynamically adjust the frame header matching length according to the current signal-to-noise ratio, bit error rate and Doppler frequency change rate;

[0014] By combining the frame header information of multiple frames, a comprehensive judgment is made as to whether frame synchronization is achieved;

[0015] The decision threshold is dynamically adjusted according to the current channel conditions, bit error rate and Doppler frequency change rate.

[0016] Optionally, the method further includes detecting phase ambiguity and performing phase correction and locking, specifically including:

[0017] Analyze the phase information of the frame header to detect whether there is phase ambiguity;

[0018] If phase ambiguity is detected, phase rotation correction is performed by rotating the received signal by 180 degrees or other fixed angles;

[0019] The receiving end simultaneously assumes multiple possible phase states, performs frame synchronization matching on each of them, and selects the phase state with the best matching result as the final phase;

[0020] After phase correction, the current phase state is locked.

[0021] Optionally, the step of comprehensively judging whether frame synchronization is achieved by combining frame header information of multiple frames includes:

[0022] Combine the frame header information of two or more frames for matching. If the matching results of multiple frames all meet the preset judgment threshold, the frame synchronization is considered successful.

[0023] The decision threshold is dynamically adjusted according to the current signal-to-noise ratio, bit error rate and Doppler frequency change rate to adapt to different channel conditions.

[0024] Optionally, dynamically adjusting the decision threshold according to current channel conditions, bit error rate, and Doppler frequency change rate further includes estimating the Doppler frequency and its change rate based on the frequency characteristics of the received signal, and performing frequency compensation on the received signal, specifically including:

[0025] Use a frequency estimation algorithm based on fast Fourier transform or a tracking algorithm based on Kalman filter to analyze the frequency changes of the received signal;

[0026] Based on the estimated Doppler frequency and its changing rate, the received signal is frequency compensated to eliminate the frequency offset caused by the Doppler effect.

[0027] Optionally, manage the frame synchronization status, specifically including:

[0028] In the initial synchronization stage, if three consecutive frames are matched successfully, the system enters the formal synchronization state;

[0029] In the synchronization state, if two consecutive frames fail to match, synchronization is lost and the initial synchronization state is re-entered.

[0030] In a second aspect, a frame synchronization device based on soft information filtering and phase ambiguity resolution is provided, the device comprising:

[0031] The demodulation module is used to receive and demodulate the signal at the receiving end and output soft information;

[0032] A soft information filtering module is used to filter the soft information and remove bad values, and to smooth the retained soft information; wherein the smoothing is achieved by sliding window averaging or weighted averaging;

[0033] The frame header matching module is used to match the filtered soft information with the predefined frame header and calculate the matching result. For long frame headers, segmented matching and parallel processing are adopted, and the matching result is obtained by weighted summation.

[0034] The judgment module is used to judge whether the synchronization is successful based on the matching result and the preset judgment threshold, and output a frame synchronization signal when the frame synchronization is successful.

[0035] Optionally, the device further comprises:

[0036] The synchronization state management module is used to manage the frame synchronization state and control the switching between initial synchronization, formal synchronization and out-of-sync state;

[0037] Doppler frequency estimation and compensation module, used to estimate the Doppler frequency and its rate of change, and perform frequency compensation on the received signal;

[0038] Dynamic frame header adjustment module, used to dynamically adjust the frame header matching length according to the current signal-to-noise ratio, bit error rate and Doppler frequency change rate;

[0039] A multi-frame joint detection module is used to comprehensively determine whether frame synchronization is achieved by combining the frame header information of multiple frames;

[0040] Adaptive decision threshold module, used to dynamically adjust the decision threshold according to current channel conditions, bit error rate and Doppler frequency change rate;

[0041] The phase ambiguity processing module is used to detect phase ambiguity and perform phase correction and locking.

[0042] In a third aspect, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the frame synchronization method described in any one of the first aspects is implemented.

[0043] In a fourth aspect, a computer program product is provided, comprising a computer program / instruction, which implements the frame synchronization method described in any one of the first aspects when the computer program / instruction is executed by a processor.

[0044] The beneficial effects of the technical solutions provided in the embodiments of the present application include at least:

[0045] Improve frame synchronization accuracy: By utilizing soft information and soft information filtering mechanism, the present invention can more accurately identify frame headers, reduce misjudgments and missed judgments, and is particularly suitable for low signal-to-noise ratio (below 0dB) environments.

[0046] Enhanced robustness: In an environment with low signal-to-noise ratio (below 0dB) and large Doppler frequency change rate, the present invention can effectively reduce the bit error rate and improve the robustness of the system.

[0047] Reducing the probability of missed alarms and false alarms: Through soft information filtering and the setting of decision thresholds, the present invention can effectively reduce the probability of missed alarms and false alarms and improve the reliability of the system.

[0048] Solving the phase ambiguity problem: By introducing a phase ambiguity detection and correction mechanism, the present invention can effectively solve the phase ambiguity problem at the receiving end and ensure the correctness of frame synchronization and data demodulation.

[0049] Dynamic adaptation to channel changes: Through dynamic frame header adjustment and adaptive decision threshold, the present invention can dynamically adjust the frame synchronization strategy according to channel conditions and adapt to different communication environments. It is particularly suitable for environments with long frame headers (such as 96 bits) and low signal-to-noise ratio (below 0dB).

[0050] Doppler frequency compensation: By introducing the Doppler frequency estimation and compensation mechanism, the present invention can effectively eliminate the frequency offset caused by the Doppler effect and ensure the accuracy of frame synchronization. It is particularly suitable for environments with large Doppler frequency change rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other implementation drawings based on the provided drawings without inventive effort.

[0052] Figure 1 A flowchart of a frame synchronization method based on soft information filtering and phase ambiguity resolution provided in an embodiment of the present application;

[0053] Figure 2 A block diagram of a frame synchronization device based on soft information filtering and phase ambiguity resolution provided in an embodiment of the present application. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0055] In the description of the present invention, the terms "comprise", "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, product or equipment comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may also include other steps or units that are not explicitly listed but are inherent to these processes, methods, products or equipment, or steps or units that are added based on further optimization solutions conceived by the present invention.

[0056] The purpose of the present invention is to provide a frame synchronization method and device based on soft information filtering and phase ambiguity resolution. By utilizing demodulated soft information (LLR, Log-Likelihood Ratio) for frame synchronization and combining it with phase ambiguity resolution technology, the method and device are particularly suitable for processing the frame synchronization problem of long frame headers (such as 96 bits) in a low signal-to-noise ratio (below 0dB) environment. In addition, the accuracy and robustness of frame synchronization are improved when the Doppler frequency change rate is large, the probability of missed alarms and false alarms is reduced, and the phase ambiguity problem is resolved at the same time.

[0057] In order to achieve the above purpose, the present invention provides the following technical solutions, please refer to Figure 1 , which shows a flow chart of a frame synchronization method based on soft information filtering and phase ambiguity resolution provided by an embodiment of the present application, which may include the following steps:

[0058] S1, the receiving end receives the signal and demodulates it, outputting soft information.

[0059] S2, filters the soft information and removes bad values, and smoothes the retained soft information.

[0060] The smoothing process is achieved by sliding window averaging or weighted averaging.

[0061] S3, matches the filtered soft information with the predefined frame header and calculates the matching result.

[0062] For long frame headers, segmented matching and parallel processing are used, and the matching results are obtained through weighted summation.

[0063] S4, judging whether the synchronization is successful based on the matching result and the preset decision threshold; when the frame synchronization is successful, outputting the frame synchronization signal.

[0064] In an embodiment of the present application, the method further includes:

[0065] S5 manages the frame synchronization state and controls the switching between initial synchronization, formal synchronization and out-of-sync states.

[0066] S6, dynamically adjust the frame header matching length according to the current signal-to-noise ratio, bit error rate and Doppler frequency change rate.

[0067] S7, comprehensively judging whether frame synchronization is achieved by combining frame header information of multiple frames.

[0068] S8, dynamically adjust the decision threshold according to the current channel conditions, bit error rate and Doppler frequency change rate.

[0069] S9, detects phase ambiguity and performs phase correction and locking.

[0070] Among them, after S5, Doppler frequency estimation and compensation may also be included, specifically including:

[0071] Use a frequency estimation algorithm based on fast Fourier transform or a tracking algorithm based on Kalman filtering to analyze the frequency changes of the received signal; based on the estimated Doppler frequency and its rate of change, perform frequency compensation on the received signal to eliminate the frequency offset caused by the Doppler effect.

[0072] In the above steps, the frame header matching length is dynamically adjusted based on the current signal-to-noise ratio, bit error rate, and Doppler frequency change rate; a comprehensive determination is made by combining the frame header information of multiple frames to determine whether frame synchronization has been achieved; and a decision threshold is dynamically adjusted based on the current channel conditions, bit error rate, and Doppler frequency change rate. The step of comprehensively determining whether frame synchronization has been achieved by combining the frame header information of multiple frames includes: combining the frame header information of two or more frames for matching, and assuming that frame synchronization has been successful if the matching results of the multiple frames all meet a preset decision threshold; and dynamically adjusting the decision threshold based on the current signal-to-noise ratio, bit error rate, and Doppler frequency change rate to adapt to different channel conditions.

[0073] Detect phase ambiguity and perform phase correction and lock, including:

[0074] The phase information of the frame header is analyzed to detect whether there is phase ambiguity. If phase ambiguity is detected, phase rotation correction is performed by rotating the received signal 180 degrees or another fixed angle. The receiver simultaneously assumes multiple possible phase states and performs frame synchronization matching on each of them, selecting the phase state with the best matching result as the final phase. After phase correction, the current phase state is locked.

[0075] From the above, it can be seen that this application achieves frame synchronization and adds a phase ambiguity resolution function and a strategy for handling large Doppler frequency change rates. The details are as follows:

[0076] 1. Frame synchronization method:

[0077] Frame structure: A data frame consists of a header, data, and check bits. The header is used for frame synchronization and is typically a special character with a fixed length, such as 32 bits, 64 bits, or 96 bits. In low signal-to-noise ratio (SNR) environments (below 0 dB), a longer header length (such as 96 bits) increases the complexity of frame synchronization, making it difficult to effectively handle with traditional methods.

[0078] Soft information processing: The receiver extracts soft information (LLR) from the demodulated data. Soft information indicates the reliability of each bit. In low signal-to-noise ratio (SNR) environments (below 0dB), soft information can better reflect data reliability and avoid misjudgments caused by hard decisions.

[0079] Soft information filtering and bad value elimination: To further improve the accuracy of frame synchronization, the present invention introduces a soft information filtering and bad value elimination mechanism. The specific steps are as follows:

[0080] Bad value detection: Detects outliers (such as abnormally large or small values ​​caused by sudden noise) by analyzing the distribution of soft information. Bad values ​​typically manifest as soft information with absolute values ​​significantly greater or less than the normal range.

[0081] Bad value removal: Removes detected bad values ​​from the matching process to prevent them from negatively impacting the frame synchronization results. After removing bad values, only reliable soft information is retained for subsequent processing.

[0082] Soft information smoothing: Smoothing the retained soft information to further reduce the impact of noise. Smoothing can be achieved through sliding window averaging or weighted averaging.

[0083] Frame header matching: The filtered soft information is matched against the predefined frame header and the matching result is calculated. The matching result is obtained through weighted summation, with a value of 0 for a full match and a value between 0 and 2 for a partial match. For long frame headers (e.g., 96 bits), this invention reduces computational complexity through segmented matching and parallel processing.

[0084] Decision threshold: Set the decision threshold based on the matching result, allowing 0-2 bit errors to improve fault tolerance. In low signal-to-noise ratio environments (below 0dB), the decision threshold can be appropriately relaxed to improve the success rate of frame synchronization.

[0085] Synchronization status management: In the initial synchronization stage, if three consecutive frames are matched successfully, the system enters the formal synchronization state; in the synchronization state, if two consecutive frames fail to match, the system loses synchronization and re-enters the initial synchronization state.

[0086] 2. Phase ambiguity resolution function:

[0087] Phase ambiguity detection: During frame synchronization, the receiver may encounter phase ambiguity, meaning it cannot determine the absolute phase of the received signal. This invention introduces a phase ambiguity detection mechanism that analyzes the phase information in the frame header to detect whether phase ambiguity exists.

[0088] Phase correction: If phase ambiguity is detected, the receiver will perform phase correction based on the phase information in the frame header. Specific methods include:

[0089] Phase rotation: Attempts to eliminate phase ambiguity by rotating the received signal by 180 degrees or another fixed angle.

[0090] Multi-phase assumption: The receiver assumes multiple possible phase states simultaneously, performs frame synchronization matching on each of them, and selects the phase state with the best matching result as the final phase.

[0091] Phase lock: After phase correction, the receiver will lock the current phase state to ensure the correctness of subsequent frame synchronization and data demodulation.

[0092] 3. Strategies for handling large Doppler frequency change rates:

[0093] Doppler frequency estimation and compensation: In an environment with a large Doppler frequency change rate, the frequency of the received signal will change rapidly over time. This invention introduces a Doppler frequency estimation and compensation mechanism, the specific steps are as follows:

[0094] Doppler frequency estimation: This method estimates the current Doppler frequency and its rate of change by analyzing the frequency changes of the received signal. This can be done using either an FFT (Fast Fourier Transform)-based frequency estimation algorithm or a Kalman filter-based tracking algorithm.

[0095] Frequency compensation: Based on the estimated Doppler frequency and its rate of change, frequency compensation is performed on the received signal to eliminate the frequency offset caused by the Doppler effect and ensure the accuracy of frame synchronization.

[0096] Dynamic header adjustment: In environments with high Doppler frequency fluctuations, frame header matching may deviate. This invention introduces a dynamic header adjustment mechanism that dynamically adjusts the header matching length based on the current signal-to-noise ratio, bit error rate, and Doppler frequency fluctuations. For example, when the Doppler frequency fluctuations are high, the header matching length is adjusted from 96 bits to 95 bits to reduce the probability of sudden frame loss.

[0097] Multi-frame joint detection: To improve the reliability of frame synchronization, this invention introduces a multi-frame joint detection mechanism. By combining the header information of multiple frames for comprehensive judgment, the impact of single-frame misjudgment can be reduced. For example, the header information of two frames can be combined for matching. If the matching results of both frames meet the judgment threshold, frame synchronization is considered successful.

[0098] Adaptive Decision Threshold: Traditionally, the decision threshold is fixed. This invention introduces an adaptive decision threshold mechanism that dynamically adjusts the decision threshold based on current channel conditions, bit error rate, and Doppler frequency variation. For example, in environments with a low signal-to-noise ratio (below 0dB) and a high Doppler frequency variation, the decision threshold can be appropriately lowered to improve the success rate of frame synchronization.

[0099] 4. Processing flow:

[0100] Step 1: Signal reception and demodulation:

[0101] The receiving end receives the signal, demodulates it, and outputs soft information (LLR).

[0102] Step 2: Soft information filtering and bad value removal:

[0103] Detect bad values ​​in soft information and remove outliers.

[0104] The retained soft information is smoothed to reduce the impact of noise.

[0105] Step 3: Frame header matching:

[0106] The filtered soft information is segmented and matched with the predefined frame header to calculate the matching results.

[0107] For long frame headers (such as 96 bits), parallel processing is used to reduce computational complexity.

[0108] Step 4: Judgment and synchronization state management:

[0109] Determine whether synchronization is successful based on the matching result and the decision threshold.

[0110] Manage the synchronization status and control the switching between initial synchronization, formal synchronization and out-of-sync status.

[0111] Step 5: Doppler frequency estimation and compensation:

[0112] Estimate the Doppler frequency and its rate of change, and perform frequency compensation on the received signal.

[0113] Step 6: Phase ambiguity detection and correction:

[0114] Detect phase ambiguity, perform phase correction and lock.

[0115] Step 7: Output frame synchronization signal:

[0116] After successful synchronization, the frame synchronization signal is output to ensure the correctness of subsequent data demodulation.

[0117] From the above, it can be seen that the innovation of this application lies in:

[0118] Soft information utilization: This invention no longer uses the traditional hard decision method, but instead uses the demodulated soft information (LLR) for frame synchronization, making full use of the demodulated information to improve the accuracy of frame synchronization, and is particularly suitable for low signal-to-noise ratio (below 0dB) environments.

[0119] Soft information filtering and bad value elimination: By introducing soft information filtering and bad value elimination mechanisms, the present invention can effectively reduce the impact of outliers on frame synchronization results, increase the probability of successful matching, and reduce the probability of missed alarms and false alarms.

[0120] Phase ambiguity resolution function: By introducing a phase ambiguity detection and correction mechanism, the present invention can effectively resolve the phase ambiguity problem at the receiving end and ensure the correctness of frame synchronization and data demodulation.

[0121] Doppler frequency estimation and compensation: In an environment with a large Doppler frequency change rate, the present invention introduces a Doppler frequency estimation and compensation mechanism, which can effectively eliminate the frequency offset caused by the Doppler effect and ensure the accuracy of frame synchronization.

[0122] Dynamic frame header adjustment: A dynamic frame header adjustment mechanism is introduced to dynamically adjust the frame header matching length based on the signal-to-noise ratio, bit error rate, and Doppler frequency change rate, reducing the probability of burst frame loss. This mechanism is particularly suitable for frame synchronization with long frame headers (such as 96 bits).

[0123] Multi-frame joint detection: By combining the frame header information of multiple frames for comprehensive judgment, the impact of single-frame misjudgment is reduced and the reliability of frame synchronization is improved.

[0124] Adaptive decision threshold: An adaptive decision threshold mechanism is introduced to dynamically adjust the decision threshold based on channel conditions, bit error rate, and Doppler frequency variation rate, improving the success rate of frame synchronization. This mechanism is particularly suitable for environments with low signal-to-noise ratio (below 0dB) and large Doppler frequency variation rate.

[0125] Another optional implementation of this application is given below:

[0126] Specific steps of the frame synchronization method:

[0127] Step 1: The receiver receives the signal, demodulates it, and outputs soft information (LLR).

[0128] Step 2: Filter the soft information and remove bad values, detect and remove outliers, and retain reliable soft information.

[0129] Step 3: Match the filtered soft information with the predefined frame header and calculate the matching result. For long frame headers (such as 96 bits), segmented matching and parallel processing are used to reduce computational complexity.

[0130] Step 4: Determine whether synchronization is successful based on the matching result and the preset decision threshold.

[0131] Step 5: Manage the frame synchronization status and control the switching between initial synchronization, formal synchronization and out-of-sync status.

[0132] Step 6: Dynamically adjust the frame header matching length based on the current signal-to-noise ratio, bit error rate, and Doppler frequency change rate.

[0133] Step 7: Improve the reliability of frame synchronization by making a comprehensive judgment based on the frame header information of multiple frames.

[0134] Step 8: Dynamically adjust the decision threshold based on the current channel conditions, bit error rate, and Doppler frequency change rate.

[0135] Step 9: Detect phase ambiguity and perform phase correction and lock.

[0136] Specific implementation of the frame synchronization device:

[0137] Demodulation module: uses existing demodulation technology to output soft information (LLR).

[0138] Soft information filtering module: detects and removes bad values ​​through hardware or software, and smoothes the soft information.

[0139] Frame header matching module: This module matches the filtered soft information with the frame header using a sliding window technique. For long frame headers (e.g., 96-bit), segmented matching and parallel processing are used to reduce computational complexity.

[0140] Decision module: determines whether synchronization is successful by comparing the matching result with the decision threshold.

[0141] Synchronization status management module: realizes the management of synchronization status through the state machine.

[0142] Doppler frequency estimation and compensation module: used to estimate the Doppler frequency and its rate of change, and perform frequency compensation on the received signal to eliminate the frequency offset caused by the Doppler effect.

[0143] Dynamic frame header adjustment module: dynamically adjusts the frame header matching length according to the current signal-to-noise ratio, bit error rate and Doppler frequency change rate.

[0144] Multi-frame joint detection module: performs comprehensive judgment by combining the frame header information of multiple frames.

[0145] Adaptive decision threshold module: dynamically adjusts the decision threshold according to the current channel conditions, bit error rate and Doppler frequency change rate.

[0146] Phase ambiguity processing module: used to detect and correct phase ambiguity to ensure the correctness of frame synchronization and data demodulation.

[0147] Please refer to Figure 2 , which shows a block diagram of a frame synchronization device based on soft information filtering and phase ambiguity resolution provided by an embodiment of the present application. The device may include:

[0148] The demodulation module is used to receive and demodulate the signal at the receiving end and output soft information;

[0149] A soft information filtering module is used to filter the soft information and remove bad values, and to smooth the retained soft information; wherein the smoothing is achieved by sliding window averaging or weighted averaging;

[0150] The frame header matching module is used to match the filtered soft information with the predefined frame header and calculate the matching result. For long frame headers, segmented matching and parallel processing are adopted, and the matching result is obtained by weighted summation.

[0151] The judgment module is used to judge whether the synchronization is successful based on the matching result and the preset judgment threshold;

[0152] The synchronization status management module is used to output a frame synchronization signal when frame synchronization is successful.

[0153] Doppler frequency estimation and compensation module, used to estimate the Doppler frequency and its rate of change, and perform frequency compensation on the received signal;

[0154] Dynamic frame header adjustment module, used to dynamically adjust the frame header matching length according to the current signal-to-noise ratio, bit error rate and Doppler frequency change rate;

[0155] A multi-frame joint detection module is used to comprehensively determine whether frame synchronization is achieved by combining the frame header information of multiple frames;

[0156] Adaptive decision threshold module, used to dynamically adjust the decision threshold according to current channel conditions, bit error rate and Doppler frequency change rate;

[0157] The phase ambiguity processing module is used to detect phase ambiguity and perform phase correction and locking.

[0158] The specific limitations of the frame synchronization apparatus based on soft information filtering and phase ambiguity resolution can be found in the limitations of the frame synchronization method based on soft information filtering and phase ambiguity resolution described above and will not be further elaborated here. Each module in the aforementioned frame synchronization apparatus based on soft information filtering and phase ambiguity resolution can be implemented in whole or in part via software, hardware, or a combination thereof. Each of these modules can be embedded in or independent of a processor in a computer device in hardware form, or can be stored in a memory in the computer device in software form, so that the processor can call and execute the corresponding operations of each of these modules.

[0159] In one embodiment, a computer-readable storage medium is further provided, on which a computer program is stored, which involves all or part of the processes in the above-mentioned embodiment method.

[0160] In one embodiment, a computer program product is also provided, including a computer program / instruction, which involves all or part of the process in the above embodiment method.

[0161] Those skilled in the art will understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in M ​​forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (SyMchliMk) DRAM (SLDRAM), memory bus (RaMbus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0162] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0163] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A frame synchronization method based on soft information filtering and phase ambiguity resolution, characterized in that: The method comprises: The receiving end receives the signal, demodulates it, and outputs soft information; Filtering the soft information and removing bad values, and smoothing the retained soft information; wherein the smoothing is achieved by sliding window averaging or weighted averaging; Match the filtered soft information with the predefined frame header and calculate the matching result. For long frame headers, segment matching and parallel processing are used, and the matching result is obtained by weighted summation. According to the matching result and the preset judgment threshold, it is judged whether the synchronization is successful; when the frame synchronization is successful, the frame synchronization signal is output; The method further comprises: Manage the frame synchronization status and control the switching between initial synchronization, formal synchronization and out-of-sync status; Dynamically adjust the frame header matching length according to the current signal-to-noise ratio, bit error rate and Doppler frequency change rate; By combining the frame header information of multiple frames, a comprehensive judgment is made as to whether frame synchronization is achieved; Dynamically adjust the decision threshold based on current channel conditions, bit error rate, and Doppler frequency change rate; The method further includes detecting phase ambiguity and performing phase correction and locking, specifically comprising: Analyze the phase information of the frame header to detect whether there is phase ambiguity; If phase ambiguity is detected, phase rotation correction is performed by rotating the received signal by 180 degrees or other fixed angles; The receiving end simultaneously assumes multiple possible phase states, performs frame synchronization matching on each of them, and selects the phase state with the best matching result as the final phase; After phase correction, the current phase state is locked.

2. The frame synchronization method according to claim 1, wherein: The step of comprehensively judging whether frame synchronization is achieved by combining frame header information of multiple frames includes: Combine the frame header information of two or more frames for matching. If the matching results of multiple frames all meet the preset judgment threshold, the frame synchronization is considered successful. The decision threshold is dynamically adjusted according to the current signal-to-noise ratio, bit error rate and Doppler frequency change rate to adapt to different channel conditions.

3. The frame synchronization method according to claim 1, wherein: Dynamically adjusting the decision threshold based on current channel conditions, bit error rate, and Doppler frequency change rate also includes estimating the Doppler frequency and its change rate based on the frequency characteristics of the received signal and performing frequency compensation on the received signal. Specifically, this includes: Use a frequency estimation algorithm based on fast Fourier transform or a tracking algorithm based on Kalman filter to analyze the frequency changes of the received signal; Based on the estimated Doppler frequency and its changing rate, the received signal is frequency compensated to eliminate the frequency offset caused by the Doppler effect.

4. The frame synchronization method according to claim 1, wherein: Manage frame synchronization status, including: In the initial synchronization stage, if three consecutive frames are matched successfully, the system enters the formal synchronization state; In the synchronization state, if two consecutive frames fail to match, synchronization is lost and the initial synchronization state is re-entered.

5. A frame synchronization device based on soft information filtering and phase ambiguity resolution, characterized in that: The device comprises: The demodulation module is used to receive and demodulate the signal at the receiving end and output soft information; A soft information filtering module is used to filter the soft information and remove bad values, and to smooth the retained soft information; wherein the smoothing is achieved by sliding window averaging or weighted averaging; The frame header matching module is used to match the filtered soft information with the predefined frame header and calculate the matching result. For long frame headers, segmented matching and parallel processing are adopted, and the matching result is obtained by weighted summation. The judgment module is used to judge whether the synchronization is successful based on the matching result and the preset judgment threshold, and output a frame synchronization signal when the frame synchronization is successful; The synchronization state management module is used to manage the frame synchronization state and control the switching between initial synchronization, formal synchronization and out-of-sync state; Doppler frequency estimation and compensation module, used to estimate the Doppler frequency and its rate of change, and perform frequency compensation on the received signal; Dynamic frame header adjustment module, used to dynamically adjust the frame header matching length according to the current signal-to-noise ratio, bit error rate and Doppler frequency change rate; A multi-frame joint detection module is used to comprehensively determine whether frame synchronization is achieved by combining the frame header information of multiple frames; Adaptive decision threshold module, used to dynamically adjust the decision threshold according to current channel conditions, bit error rate and Doppler frequency change rate; Phase ambiguity processing module, used to detect phase ambiguity and perform phase correction and locking; Analyze the phase information of the frame header to detect whether there is phase ambiguity; If phase ambiguity is detected, phase rotation correction is performed by rotating the received signal by 180 degrees or other fixed angles; The receiving end simultaneously assumes multiple possible phase states, performs frame synchronization matching on each of them, and selects the phase state with the best matching result as the final phase; After phase correction, the current phase state is locked.

6. A computer-readable storage medium, characterized in that A computer program is stored thereon, and when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

7. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

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