Frame synchronization method and device based on soft information filtering and dephasing ambiguity

Abstract

The invention discloses a frame synchronization method and device based on soft information filtering and dephasing ambiguity. Frame synchronization is performed by using demodulated soft information, and new strategies such as soft information filtering, phase ambiguity resolution, Doppler frequency estimation and compensation, dynamic frame header adjustment, multi-frame joint detection and adaptive judgment threshold are combined, so that the accuracy and robustness of frame synchronization are remarkably improved; the method is suitable for processing the frame synchronization problem of a long frame header in a low signal-to-noise ratio environment, and effectively solves the problem of phase ambiguity under the condition that the Doppler frequency change rate is large.

Description

Technical Field

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

[0002] In a digital communication system, frame synchronization is a crucial step to ensure that the receiving end can correctly identify and extract data frames. Traditional frame synchronization methods usually rely on hard decisions, that is, by comparing the received data bit by bit with a predefined frame header for matching. However, in an environment with a low signal-to-noise ratio (below 0 dB), traditional frame synchronization methods are prone to misjudgment, resulting in frame synchronization failure or an increase in the bit error rate. In addition, when the frame header length is long (such as 96 bits), traditional frame synchronization methods have a high computational complexity and are sensitive to outliers (such as burst noise), easily leading 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 an environment with a large Doppler frequency change rate (such as high-speed mobile communication, satellite communication, etc.), the frequency of the received signal changes rapidly over time, making it difficult for traditional frame synchronization methods to effectively track the signal changes, further increasing the difficulty of frame synchronization. Therefore, how to achieve reliable frame synchronization in an environment with a large Doppler frequency change rate has become an important challenge in current communication systems. Summary of the Invention

[0004] Based on this, the embodiments of the present application provide a frame synchronization method and apparatus based on soft information filtering and phase ambiguity resolution. This method performs frame synchronization by using the demodulated soft information (LLR, Log-Likelihood Ratio), and combines phase ambiguity resolution technology. It is particularly suitable for frame synchronization problems with a long frame header (such as 96 bits) in an environment with a low signal-to-noise ratio (below 0 dB), and can improve the accuracy and robustness of frame synchronization, reduce the probability of missed alarms and false alarms, and solve the phase ambiguity problem at the same time in the case of a large Doppler frequency change rate.

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

[0006] The receiving end receives a signal and demodulates it to output soft information;

[0007] Filter the soft information and remove bad values, and perform smoothing processing on the remaining soft information; wherein, the smoothing processing is implemented by means of moving window averaging or weighted averaging;

[0008] Match the filtered soft information with a predefined frame header and calculate the matching result; among them, for long frame headers, segmented matching and parallel processing are adopted, and the matching result is obtained through weighted summation;

[0009] Judge whether synchronization is successful according to the matching result and a preset decision threshold;

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

[0011] Optionally, the method further includes:

[0012] Manage the frame synchronization state and control the switching of initial synchronization, formal synchronization, and out-of-synchronization states;

[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] Comprehensively judge whether frame synchronization is achieved by jointly using the frame header information of multiple frames;

[0015] Dynamically adjust the decision threshold according to the current channel condition, 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, perform phase rotation correction by rotating the received signal by 180 degrees or other fixed angles;

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

[0020] After phase correction, lock the current phase state.

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

[0022] Jointly match the frame header information of two frames or multiple frames. If the matching results of multiple frames all meet the preset decision threshold, it is considered that frame synchronization is successful;

[0023] Dynamically adjust the decision threshold 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 the current channel condition, 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 the fast Fourier transform or a tracking algorithm based on Kalman filtering to analyze the frequency change of the received signal;

[0026] According to the estimated Doppler frequency and its change rate, perform frequency compensation on the received signal to eliminate the frequency offset caused by the Doppler effect.

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

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

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

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

[0031] A demodulation module for receiving and demodulating the received signal at the receiving end and outputting soft information;

[0032] A soft information filtering module for filtering the soft information and removing bad values, and performing smoothing processing on the remaining soft information; wherein, the smoothing processing is implemented by means of moving window averaging or weighted averaging;

[0033] A frame header matching module for matching the filtered soft information with a predefined frame header and calculating the matching result; wherein, for a long frame header, segmented matching and parallel processing are adopted, and the matching result is obtained by weighted summation;

[0034] A decision module for judging whether synchronization is successful according to the matching result and a preset decision threshold, and outputting a frame synchronization signal when frame synchronization is successful.

[0035] Optionally, the device further includes:

[0036] A synchronization state management module for managing the frame synchronization state and controlling the switching of the initial synchronization, formal synchronization, and out-of-synchronization states;

[0037] A Doppler frequency estimation and compensation module for estimating the Doppler frequency and its change rate and performing frequency compensation on the received signal;

[0038] A dynamic frame header adjustment module for dynamically adjusting 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 for comprehensively judging whether frame synchronization is achieved by combining the frame header information of multiple frames;

[0040] An adaptive decision threshold module for dynamically adjusting the decision threshold according to the current channel condition, bit error rate, and Doppler frequency change rate;

[0041] A phase ambiguity processing module for detecting phase ambiguity and performing 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 above is implemented.

[0043] In a fourth aspect, a computer program product is provided, including a computer program / instructions. When the computer program / instructions are executed by a processor, the frame synchronization method described in any one of the first aspects above is implemented.

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

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

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

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

[0048] Solve 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] Dynamically adapt to channel changes: Through dynamic frame header adjustment and adaptive decision thresholds, the present invention can dynamically adjust the frame synchronization strategy according to the channel condition, adapt to different communication environments, and is particularly suitable for environments with long frame headers (such as 96 bit) and low signal-to-noise ratio (below 0 dB).

[0050] Doppler frequency compensation: By introducing a 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, and is particularly suitable for environments with a large Doppler frequency change rate. 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 will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only exemplary. For those of ordinary skill in the art, without creative efforts, other implementation drawings can also be obtained based on the provided drawings.

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

[0053] Figure 2 It is 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. Specific Embodiments

[0054] In order to make the objectives, technical solutions, and advantages of the present application clearer, the following further details the present application in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

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

[0056] The objective of the present invention is to provide a frame synchronization method and device based on soft information filtering and phase ambiguity resolution. By using the demodulated soft information (LLR, Log-Likelihood Ratio) for frame synchronization and combining the phase ambiguity resolution technology, it is particularly suitable for handling frame synchronization problems with long frame headers (such as 96 bits) in low signal-to-noise ratio (below 0 dB) environments. Moreover, in the case of a large Doppler frequency change rate, it improves the accuracy and robustness of frame synchronization, reduces the probabilities of missed alarms and false alarms, and simultaneously solves the phase ambiguity problem.

[0057] To achieve the above objective, the present invention provides the following technical solutions. Please refer to Figure 1 , which shows a flowchart of a frame synchronization method based on soft information filtering and phase ambiguity resolution provided by an embodiment of the present application, and may include the following steps:

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

[0059] S2. Filter the soft information and remove the bad values, and smooth the remaining soft information.

[0060] Among them, the smoothing process is implemented by means of moving window averaging or weighted averaging.

[0061] S3. Match the filtered soft information with a predefined frame header and calculate the matching result.

[0062] Among them, for long frame headers, segmented matching and parallel processing are adopted, and the matching result is obtained by weighted summation.

[0063] S4. According to the matching result and a preset decision threshold, determine whether synchronization is successful; when frame synchronization is successful, output a frame synchronization signal.

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

[0065] S5. Manage the frame synchronization state and control the switching of the 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 judge whether frame synchronization is achieved by combining the frame header information of multiple frames.

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

[0069] S9. Detect the phase ambiguity and perform phase correction and locking.

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

[0071] Use a frequency estimation algorithm based on fast Fourier transform or a tracking algorithm based on Kalman filter to analyze the frequency change of the received signal; according to the estimated Doppler frequency and its change rate, 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 according to the current signal-to-noise ratio, bit error rate, and Doppler frequency change rate; it is comprehensively judged whether frame synchronization is achieved by combining the frame header information of multiple frames; the decision threshold is dynamically adjusted according to the current channel condition, bit error rate, and Doppler frequency change rate. Among them, the step of comprehensively judging whether frame synchronization is achieved by combining the frame header information of multiple frames includes: combining the frame header information of two or more frames for matching, and if the matching results of multiple frames all meet the preset decision threshold, it is considered that frame synchronization is 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.

[0073] Detect the phase ambiguity, and perform phase correction and locking, specifically including:

[0074] Analyze the phase information of the frame header to detect whether there is phase ambiguity; if phase ambiguity is detected, perform phase rotation correction by rotating the received signal by 180 degrees or other fixed angles; the receiving end simultaneously assumes multiple possible phase states and performs frame synchronization matching respectively, and selects the phase state with the best matching result as the final phase; after phase correction, lock the current phase state.

[0075] In summary, it can be seen that the present application realizes frame synchronization, and on this basis, adds a function of resolving phase ambiguity and a processing strategy for a large Doppler frequency change rate, specifically as follows:

[0076] 1. Frame synchronization method:

[0077] Frame structure: The data frame consists of a frame header, a data part, and a check bit. The frame header is used for frame synchronization and is usually a special character with a fixed length such as 32bit, 64bit, 96bit, etc. In an environment with a low signal-to-noise ratio (below 0dB), when the frame header length is long (such as 96bit), the complexity of frame synchronization increases, and it is difficult for traditional methods to effectively handle it.

[0078] Soft information processing: The receiving end extracts soft information (LLR) from the demodulated data, and the soft information represents the reliability of each bit. In an environment with a low signal-to-noise ratio (below 0dB), the soft information can better reflect the reliability of the data and avoid misjudgment caused by hard decision.

[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: By analyzing the distribution of soft information, detect abnormal values (such as abnormally large or small values caused by burst noise). Bad values usually show that the absolute value of the soft information is much larger or much smaller than the normal range.

[0081] Bad value elimination: Eliminate the detected bad values from the matching process to avoid their negative impact on the frame synchronization result. After eliminating the bad values, only reliable soft information is retained for subsequent processing.

[0082] Soft information smoothing processing: Smooth the retained soft information to further reduce the influence of noise. The smoothing processing can be achieved by means such as moving window averaging or weighted averaging.

[0083] Frame header matching: Match the filtered soft information with a predefined frame header and calculate the matching result. The matching result is obtained by weighted summation. When there is a full match, the output is 0. When there is a partial match, the output is a value between 0 and 2. For long frame headers (such as 96-bit), the present invention reduces the computational complexity through segmented matching and parallel processing.

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

[0085] Synchronization state management: In the initial synchronization stage, if three consecutive frames are successfully matched, it enters the formal synchronization state. In the synchronization state, if two consecutive frames fail to match, the synchronization is lost and it re-enters the initial synchronization state.

[0086] 2. Phase ambiguity resolution function:

[0087] Phase ambiguity detection: During the frame synchronization process, the receiving end may encounter the problem of phase ambiguity, that is, it is impossible to determine the absolute phase of the received signal. The present invention introduces a phase ambiguity detection mechanism to detect whether there is phase ambiguity by analyzing the phase information of the frame header.

[0088] Phase correction: If phase ambiguity is detected, the receiving end will perform phase correction according to the phase information of the frame header. The specific methods include:

[0089] Phase rotation: Try to eliminate the phase ambiguity by rotating the received signal by 180 degrees or other fixed angles.

[0090] Multiple phase hypotheses: The receiving end simultaneously assumes multiple possible phase states, performs frame synchronization matching separately, and selects the phase state with the best matching result as the final phase.

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

[0092] 3. Processing strategy for large Doppler frequency change rate:

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

[0094] Doppler frequency estimation: Estimate the current Doppler frequency and its change rate by analyzing the frequency change of the received signal. A frequency estimation algorithm based on FFT (Fast Fourier Transform) or a tracking algorithm based on Kalman filtering can be used.

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

[0096] Dynamic frame header adjustment: In an environment with a large rate of change of the Doppler frequency, the matching of the frame header may deviate. The present invention introduces a dynamic frame header adjustment mechanism to dynamically adjust the matching length of the frame header according to the current signal-to-noise ratio, bit error rate, and rate of change of the Doppler frequency. For example, when the rate of change of the Doppler frequency is large, the frame header matching length is adjusted from 96 bits to 95 bits to reduce the probability of burst frame loss.

[0097] Multi-frame joint detection: To improve the reliability of frame synchronization, the present invention introduces a multi-frame joint detection mechanism. By comprehensively judging by combining the frame header information of multiple frames, the influence of single-frame misjudgment is reduced. For example, the frame header information of two frames can be combined for matching. If the matching results of both frames meet the decision threshold, it is considered that frame synchronization is successful.

[0098] Adaptive decision threshold: The traditional decision threshold is fixed. The present invention introduces an adaptive decision threshold mechanism to dynamically adjust the decision threshold according to the current channel conditions, bit error rate, and rate of change of the Doppler frequency. For example, in an environment with a low signal-to-noise ratio (below 0 dB) and a large rate of change of the Doppler frequency, the decision threshold is appropriately reduced 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 and demodulates it to output soft information (LLR).

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

[0103] Detect bad values in the soft information and eliminate outliers.

[0104] Smooth the remaining soft information to reduce the influence of noise.

[0105] Step 3: Frame header matching:

[0106] Segmentally match the filtered soft information with the predefined frame header and calculate the matching result.

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

[0108] Step 4: Decision and synchronization status management:

[0109] Judge whether synchronization is successful according to the matching result and the decision threshold.

[0110] Manage the synchronization status and control the switching between initial synchronization, formal synchronization, and out-of-synchronization 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 the phase ambiguity, and perform phase correction and locking.

[0115] Step 7: Output the frame synchronization signal:

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

[0117] In summary, the innovative points of this application are as follows:

[0118] Soft information utilization: Instead of using the traditional hard decision method, the present invention uses the demodulated soft information (LLR) for frame synchronization, making full use of the demodulated information, improving the accuracy of frame synchronization, and being particularly suitable for environments with low signal-to-noise ratio (below 0 dB).

[0119] Soft information filtering and bad value rejection: By introducing a soft information filtering and bad value rejection mechanism, the present invention can effectively reduce the influence of outliers on the frame synchronization result, increase the probability of successful matching, and reduce the probabilities 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 solve 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 rate of change of the Doppler frequency, 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: By introducing a dynamic frame header adjustment mechanism, the frame header matching length is dynamically adjusted according to the signal-to-noise ratio, bit error rate, and rate of change of the Doppler frequency, reducing the probability of sudden frame loss, and being particularly suitable for frame synchronization with a long frame header (such as 96 bit).

[0123] Multi-frame joint detection: By comprehensively judging by combining the frame header information of multiple frames, the influence of single-frame misjudgment is reduced, and the reliability of frame synchronization is improved.

[0124] Adaptive decision threshold: Introduce an adaptive decision threshold mechanism to dynamically adjust the decision threshold according to the channel conditions, bit error rate, and Doppler frequency change rate, improving the success rate of frame synchronization. It is especially suitable for environments with low signal-to-noise ratio (below 0 dB) and large Doppler frequency change rate.

[0125] The following gives another optional implementation manner of the present application:

[0126] Specific steps of the frame synchronization method:

[0127] Step 1: The receiving end receives the signal and demodulates it to output soft information (LLR).

[0128] Step 2: Filter the soft information and eliminate bad values, detect and eliminate 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 a long frame header (such as 96 bit), use segmented matching and parallel processing to reduce the computational complexity.

[0130] Step 4: According to the matching result and the preset decision threshold, determine whether synchronization is successful.

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

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

[0133] Step 7: Make a comprehensive judgment by combining the frame header information of multiple frames to improve the reliability of frame synchronization.

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

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

[0136] Specific implementation of the frame synchronization device:

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

[0138] Soft information filtering module: Implement bad value detection and elimination through hardware or software, and perform smoothing processing on the soft information.

[0139] Frame header matching module: Match the filtered soft information with the frame header through the sliding window technique. For a long frame header (such as 96 bit), use segmented matching and parallel processing to reduce the computational complexity.

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

[0141] Synchronization status management module: Manage the synchronization status through a state machine.

[0142] Doppler frequency estimation and compensation module: 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 adjust the frame header matching length according to the current signal-to-noise ratio, bit error rate, and Doppler frequency rate of change.

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

[0145] Adaptive decision threshold module: Dynamically adjust the decision threshold according to the current channel condition, bit error rate, and Doppler frequency rate of change.

[0146] Phase ambiguity processing module: 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] Demodulation module: Receive and demodulate the received signal at the receiving end, and output soft information;

[0149] Soft information filtering module: Filter and remove bad values from the soft information, and perform smoothing processing on the remaining soft information; wherein, the smoothing processing is implemented by means of moving window averaging or weighted averaging;

[0150] Frame header matching module: Match the filtered soft information with a predefined frame header, and calculate the matching result; wherein, for long frame headers, segmented matching and parallel processing are adopted, and the matching result is obtained by weighted summation;

[0151] Decision module: Determine whether synchronization is successful according to the matching result and a preset decision threshold;

[0152] Synchronization status management module: Output a frame synchronization signal when frame synchronization is successful.

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

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

[0155] A multi-frame joint detection module, which is used to comprehensively judge whether frame synchronization is achieved by jointly detecting the frame header information of multiple frames;

[0156] An adaptive decision threshold module, which is used to dynamically adjust the decision threshold according to the current channel condition, bit error rate and Doppler frequency change rate;

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

[0158] For the specific limitations of the frame synchronization device based on soft information filtering and phase ambiguity resolution, reference can be made to the limitations of the frame synchronization method based on soft information filtering and phase ambiguity resolution in the above text, which will not be elaborated here. Each module in the above frame synchronization device based on soft information filtering and phase ambiguity resolution can be implemented in whole or in part by software, hardware and their combination. The above modules can be embedded in the processor of the computer device in hardware form or independent of it, or stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to the above modules.

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

[0160] In one embodiment, a computer program product is further provided, including a computer program / instructions, covering all or part of the processes in the method of the above embodiment.

[0161] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing 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 methods. Among them, any reference to a memory, storage, database, or other medium used in the various embodiments provided in the present application can include non-volatile and / or volatile memories. Non-volatile memories can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memories can 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 (DDR SDRAM), 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 embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0163] The above embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to 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 the long frame header, segment matching and parallel processing are adopted, and the matching result is obtained by weighted summation; Whether synchronization is successful is determined based on the matching result and the preset decision threshold; when frame synchronization is successful, a frame synchronization signal is output.

2. The frame synchronization method according to claim 1, characterized in that: 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; The decision threshold is dynamically adjusted according to the current channel conditions, bit error rate and Doppler frequency change rate.

3. The frame synchronization method according to claim 1, characterized in that: The method also includes detecting phase ambiguity and performing phase correction and locking, specifically including: 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 assumes multiple possible phase states at the same time, 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.

4. The frame synchronization method according to claim 2, characterized in that: The step of comprehensively judging whether frame synchronization is achieved by combining frame header information of multiple frames comprises: Combine the frame header information of two or more frames for matching. If the matching results of multiple frames all meet the preset decision 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.

5. The frame synchronization method according to claim 2, characterized in that: Dynamically adjusting the decision threshold according to the 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 including: 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.

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

7. A frame synchronization device based on soft information filtering and phase ambiguity resolution, characterized in that: The device comprises: The demodulation module is used for receiving and demodulating the signal at the receiving end and outputting 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 the long frame header, segment 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 according to the matching result and the preset judgment threshold, and output the frame synchronization signal when the frame synchronization is successful.

8. The frame synchronization device according to claim 7, characterized in that: The device also includes: The synchronization state management module is used to manage the frame synchronization state and control the switching between the initial synchronization, formal synchronization and out-of-sync state; Doppler frequency estimation and compensation module, used to estimate the Doppler frequency and its change rate, and perform frequency compensation on the received signal; A dynamic frame header adjustment module is 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 judge whether frame synchronization is achieved by combining frame header information of multiple frames; Adaptive decision threshold module, used to dynamically adjust the decision threshold according to the current channel conditions, bit error rate and Doppler frequency change rate; The phase ambiguity processing module is used to detect phase ambiguity and perform phase correction and locking.

9. 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 6 are implemented.

10. 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 6 are implemented.

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