Device and method for identifying and judging multiple types of frames in meteor trail communication

Abstract

The present invention discloses a device and method for multi-type frame recognition and judgment in meteor trail communication, belonging to the field of burst communication technology; the multi-type frame recognition device includes: a matching filter for estimating the position of the frame header during transmission, one or more specific frame type identifiers for completing the comparison between the frame header distance and the set distance, and a frame type judge for judging the received frame type. The present invention only requires one set of frame header related matching circuits, and in the case of a large number of frame types, the method can complete the task of frame type recognition more stably and efficiently. In addition, the method strengthens the synchronization constraint conditions and does not have the problem of multiple frame header sequences interfering with each other. Therefore, in the case of low signal-to-noise ratio, the method has a lower probability of misjudgment and false detection.

Description

Technical Field

[0001] The present invention relates to the technical field of burst communication, and in particular discloses a method and device for identifying and judging multiple types of frames suitable for meteor trail communication. Background Art

[0002] Meteor trail communication is a burst communication method with a random channel. Meteor trail channels appear at random times and have random durations. To address this randomness, meteor trail communication systems typically improve channel utilization by sending frames tailored to current channel conditions. These frames typically have similar structures, but each carries varying amounts of data. Therefore, a meteor trail receiver must correctly identify the received frame type and process it accordingly to parse the correct data.

[0003] Traditional frame type identification methods insert a frame header before the data segment, distinguishing frame types based on the differences in the frame header. The key is to select a set of sequences with weak cross-correlation as frame headers and assign a dedicated frame header to each frame type. In this traditional frame type identification method, the receiver performs parallel correlation operations on the received signal based on the weak correlation between different frame headers. When the correlation result of a particular channel exceeds a preset threshold, the receiver considers the frame type identification complete. However, this method has the disadvantage of a limited number of selectable sequences, which significantly limits the transmitter's framing flexibility. Furthermore, during the correlation calculation process, the receiver needs to configure a matching circuit for each frame header type. This traditional method consumes a large amount of hardware resources, making its implementation difficult. Furthermore, due to mutual interference between sequences, the synchronization decision results of this traditional frame type identification method are more susceptible to noise when the signal-to-noise ratio is low, resulting in false positives, missed detections, and misdetections of received frames. Summary of the Invention

[0004] The present invention aims to avoid the problems in the above-mentioned context, such as the difficulty in achieving the goal when the number of sequences is limited and the number of frames is large, and the high probability of misjudgment and false detection under low signal-to-noise ratios, and to provide a multi-type frame recognition and judgment method and device for meteor trail communications, which can meet the needs of framing of arbitrary lengths and their judgment under the condition of low additional transmission overhead, thereby making more efficient use of limited channel resources. In addition, the present method only requires one set of frame header-related matching circuits, and in the case of a large number of frame types, the present method can complete the task of frame type recognition more stably and efficiently. In addition, the present method strengthens the synchronization constraints, and there is no problem of multiple frame header sequences interfering with each other, so under low signal-to-noise ratio conditions, the present method has a lower probability of misjudgment and false detection.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A device for multi-type frame recognition and judgment suitable for meteor trail communication, comprising a digital down-converter, a low-pass filter and a data memory connected in sequence, for performing front-end processing on the obtained baseband signal; further comprising a matched filter, a frame type identifier and a frame type judge;

[0007] The received intermediate frequency signal is sampled, down-converted, and low-pass filtered to obtain a complex baseband signal, which is then fed into a matched filter by the demodulator. The matched filter performs a correlation operation between the received signal and the local frame header sequence to estimate the position of the frame header during transmission, and outputs a correlation peak indicating the position of the frame header in the complex baseband signal. The frame type identifier determines the spacing between frame headers using the correlation peak, and outputs a frame type identification signal when the spacing between frame headers meets the set distance. The frame type determinator determines the type of the currently received frame based on the frame type identification signal output by the frame identifier. When frame type identification is successful, information for subsequent signal processing is output, and the frame type determinator resets the working status of all frame type determinators.

[0008] Furthermore, the frame type identifier is provided with at least one or more, and multiple frame type identifiers are connected in parallel; the difference between multiple frame type identifiers is that the lengths of their frame type decision intervals are different; both ends of each frame type identifier are respectively connected to the matching filter and the frame type decider.

[0009] A method for multi-type frame recognition and judgment applicable to meteor trail communication is implemented by the above-mentioned multi-type frame recognition and judgment device applicable to meteor trail communication, and the specific steps are as follows:

[0010] Step 1: The transmitter inserts a frame header before and after the data segment of the baseband signal, and the distance between the two frame headers is the data segment length T;

[0011] Step 2: The matched filter at the receiving end works continuously to calculate the received data;

[0012] Step 3: The frame type identifier sets the initial time of frame type determination to T0.

[0013] Step 4: The decision interval of the frame type identifier used to identify the signal sent in step 1 is (T0, T0+T]; the frame type identifier searches for the maximum value within the range of (T0, T0+T], and the position of the maximum value is T1;

[0014] Step 5: Determine whether the position of T1 satisfies a certain frame type decision constraint. If the position of T1 does not satisfy the corresponding frame type decision constraint, proceed to step 6. If the position of T1 satisfies the corresponding frame type decision constraint, take T1 as the correlation peak and proceed to step 7.

[0015] Step 6: If the frame type identification fails, the initial time T1 of the next frame type determination is used as T0, and steps 4 to 5 are repeated;

[0016] Step 7: If the frame type is successfully identified, the frame type decision information is output for subsequent signal processing; and the initial time T1 of the next frame type decision is used as T0, and steps 4 to 5 are repeated.

[0017] Furthermore, whether the position of the correlation peak satisfies the decision constraint of a certain frame type is as follows: if the position of the correlation peak is at the end of the frame type decision interval to which it belongs, it is a successful decision; if the position of the correlation peak is not at the end of the frame type decision interval to which it belongs, it is a failed decision.

[0018] Furthermore, the frame type identifier compares the distance between the two frame headers with the length of their decision interval. When the frame header distance is equal to the length of the decision interval, the frame type identifier considers that the corresponding type of frame has been received; otherwise, it considers that the frame of this type has not been received.

[0019] Furthermore, the frame type identifier first sets the initial time and interval of frame type determination; searches for the maximum value within the frame type determination interval, and determines whether the position of the maximum value within the interval can be used as a correlation peak: when the distance between two adjacent correlation peaks is equal to the frame length set by a certain frame type identifier, the corresponding frame type identifier outputs a recognition success flag, otherwise the frame type identifier outputs a non-recognition success flag; finally, the initial time and interval of frame type determination are updated.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] Compared with traditional methods, this invention only adds a frame header at the end of the data segment, making the impact on data transmission almost negligible. It also reduces the use of matched filters, significantly reducing the complexity of related calculations. It also strengthens synchronization constraints, ensuring algorithm reliability. The algorithm is simple, stable, and reliable. While maintaining low transmission and computational overhead, it addresses the limited number of sequences and the difficulty in selecting them in traditional methods, meeting the requirements for framing and distinguishing arbitrary lengths, thereby more efficiently utilizing limited channel resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is an application example diagram of the multi-type frame recognition and judgment device of the present invention.

[0023] Figure 2 It is a structural diagram of the multi-type frame recognition and judgment device of the present invention.

[0024] Figure 3 This is the frame structure used by the multi-type frame recognition and judgment method of the present invention.

[0025] Figure 4 It is a flow chart of the operation of the multi-type frame identifier of the present invention. DETAILED DESCRIPTION

[0026] The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings and examples.

[0027] A device for identifying and judging multiple types of frames suitable for meteor trail communication includes a matching filter, one or more specific frame type identifiers and a frame type judge.

[0028] The matched filter is used to perform correlation operation between the received signal and the local frame header sequence to estimate the position of the frame header during the transmission process.

[0029] The frame type identifier is used to compare the frame header distance with the set distance, and output a frame type identification signal when the frame header distance meets the set distance.

[0030] The frame type determiner is used to determine the type of the received frame based on the frame type identification signal output by the frame identifier, and output relevant information for the subsequent processing module to correctly complete the signal processing.

[0031] The technical solution adopted in the present invention is:

[0032] The present invention employs a specific frame structure comprising two frame headers and one data segment. The two frame headers are inserted before and after the data segment, respectively. The frame header at the front of the data segment is called frame header 1, and the frame header at the back of the data segment is called frame header 2. The present invention determines the frame type based on the fact that the distance between frame headers 1 and 2 varies from frame to frame. Therefore, the distance between frame headers 1 and 2 can be used to determine the current frame type.

[0033] The calculation method for calculating the frame header distance uses the fact that the large correlation peak is generated when the frame header portion of the received signal matches the locally stored frame header sequence. The distance between the two correlation peaks can be used to determine the distance between the two frame header segments. Therefore, as long as the data segments have different lengths, this method can distinguish different frames.

[0034] Furthermore, if it is necessary to distinguish two frames of the same length, a sequence with good cross-correlation with the current sequence can still be used as a new frame header. The present invention reduces the difficulty of selecting the frame header.

[0035] The core of a method and apparatus for multi-type frame recognition and decision-making suitable for meteor trail communications is one or more frame type identifiers arranged in parallel. These frame type identifiers differ in that they have frame type decision intervals of varying sizes. The following describes the workflow of a method and apparatus for multi-type frame recognition and decision-making suitable for meteor trail communications, using a frame type identifier corresponding to a specific frame length as an example:

[0036] 1. The transmitter inserts a frame header before and after the data segment of the baseband signal. Here, it is assumed that the distance between the two frame headers is T.

[0037] 2. The matched filter at the receiving end works continuously to perform correlation calculations on the received data;

[0038] 3. The frame type identifier corresponding to the signaling data segment frame length sets the frame type determination initial time to T0, and its frame type determination interval is [T0, T0+T];

[0039] 4. The frame type identifier searches for the maximum value in the range [T0, T0+T]. The maximum value is located at T1, assuming that T1 is a correlation peak in the range [T0, T0+T].

[0040] 5. Determine whether the T1 position meets certain frame type judgment constraints, and execute corresponding step 6 or step 7 according to the judgment result;

[0041] 6. If the position of the new maximum value satisfies the judgment constraint of the frame type, the frame type recognition is successful. The next moment is a new frame type judgment initial moment. A new frame type judgment interval is established based on the next moment, and step 4 is executed.

[0042] 7. If the position of the new maximum value does not meet the judgment constraint conditions of the frame type, the frame type recognition fails. The initial time of the frame type judgment is updated to T1, the frame type judgment interval is [T1, T1+T], and the next step is executed.

[0043] 8. The frame type identifier searches for the maximum value in the range [T0+T,T1+T]. The maximum value is located at T2, assuming that T2 is the correlation peak in the range [T1,T].

[0044] 9. Determine whether the T2 position meets the judgment constraint of a certain frame type, and execute the corresponding step 6 or step 7 according to the judgment result;

[0045] The determination of whether the position of the new maximum value satisfies the decision constraint of a certain frame type is as follows:

[0046] Successful decision: The new maximum value is located at the end of the frame type decision interval to which it belongs.

[0047] Failed judgment: The position of the new maximum value is not at the end of the frame type judgment interval to which it belongs.

[0048] Here is a more specific description:

[0049] Figure 1 This is an example diagram of an application of a multi-type frame recognition and decision device in the background art. It is arranged after the digital down-converter, low-pass filter, and data storage device, and processes the resulting complex baseband signal. Input A of the digital down-converter is a discrete digital intermediate frequency signal obtained by sampling the received intermediate frequency signal by the analog-to-digital conversion module. The type of received frame and its location in the data storage device are output to the channel estimation device, allowing the channel estimation device to completely extract the data to be processed from the correct data storage device. Only by extracting the correct data to be processed can the channel estimation device accurately estimate the channel parameters and the channel compensation device effectively compensate for the received signal. After channel compensation, the received signal is sent to the channel decoder in a conforming form, and the channel decoder outputs the original information.

[0050] Figure 2 This is a block diagram of the multi-type frame recognition and decision device of the present invention. The first step at the receiving end of the present invention is matched filtering. The receiving end feeds the complex baseband signal obtained after front-end processing into the matched filter for processing. The resulting complex baseband signal is matched with the selected frame header. When the signal and the frame header are fully matched, the matched filter outputs a large correlation peak. The position of the correlation peak indicates the location of the frame header in the complex baseband signal.

[0051] The core of the present invention is one or more frame type identifiers arranged in parallel after the matched filter. A characteristic of each frame type identifier is that it requires a specified frame type decision interval. The length of the frame type decision interval depends on the distance between the two frame headers of the frame to be detected. Therefore, the essential difference between different frame type identifiers lies in the different lengths of the frame type decision intervals set.

[0052] The frame type identifier determines the distance between frame header 1 and frame header 2. The distance between frame headers is calculated based on the principle that a correlation peak is generated when the frame header portion of the received signal matches the locally stored frame header sequence. When the distance between two adjacent correlation peaks equals the frame length set by the frame type identifier, the frame type identifier outputs a successful identification flag. When the distance between two adjacent correlation peaks does not equal the frame length set by the frame type identifier, the frame type identifier outputs a failed identification flag.

[0053] The key to the external output of the present invention is the frame type determiner, which is responsible for summarizing the output results of the frame type identifier and determining the type of the currently received frame. When the frame type is successfully identified, the frame type determiner resets the working status of all frame type determiners.

[0054] The frame structure adopted by the present invention is the basis for the implementation of the present invention. Figure 3 The two frame headers and the data segment sandwiched between them constitute the fixed frame structure of the present invention. The frame header at the front of the data segment is frame header 1, and the frame header at the back of the data segment is frame header 2. Frame header 1 and frame header 2 are two identical sequences. The present invention requires that the lengths of the data segments of different frames vary. For different data segment lengths, a sequence with good cross-correlation with the current sequence can be used as a new frame header. In the present invention, the transmitter transmits frame header 1, data segment, and frame header 2 in sequence.

[0055] Figure 4 A flowchart of the operation of the multi-type frame identifier in the present invention is shown. Taking a specific multi-type frame identifier in the present invention as an example, its operation process is described in detail.

[0056] Step 1: The multi-type frame identifier sets the initial time for frame type determination.

[0057] This time can be chosen arbitrarily; it is generally the first clock cycle of normal device operation, denoted as T0. The initial time for frame type determination is the assumed location of the first correlation peak in this method. This location is not necessarily the actual location of the correlation peak, and the choice of this location does not affect the implementation of this method. After setting the initial time for frame type determination, the multi-type frame identifier can define the first frame type determination interval. The size of this interval is determined by the length of the frame to be identified. Assuming the length of the frame to be identified is T, the first frame type determination interval is [T0, T0+T].

[0058] Step 2: The multi-type frame identifier searches for the maximum value in the entire frame type decision interval.

[0059] By scanning the entire frame type decision interval, the multi-type frame identifier selects the maximum value within the frame type decision interval [T0, T0+T], assuming that the maximum value in the interval is located at T1.

[0060] Step 3: The multi-type frame identifier determines the position of the maximum value in the interval.

[0061] After obtaining the maximum value of the current frame type decision interval, the multi-type frame identifier determines whether the maximum value position meets the current frame type decision constraint. There are two possible cases for the decision:

[0062] Successful frame type identification: If T1 is located at T0+T within the frame type decision interval, the distance between the two assumed correlation peaks is equal to the length set by the multi-type frame identifier. Therefore, T0 represents the first correlation peak, and T1(T0+T) represents the second correlation peak. Therefore, the received signal can be determined to be a frame of this type. The multi-type frame identifier outputs a frame type match success signal, sets the next moment as a new frame type decision initial moment, establishes a new frame type decision interval based on the new frame type decision initial moment, and executes step 2.

[0063] Frame type identification failure: If T1 is not at T0+T within the frame type determination interval, the distance between the two assumed correlation peaks is not equal to the length set by the multi-type frame identifier. Therefore, T0 cannot be the true first correlation peak, while T1 may be the first correlation peak. Therefore, it can be determined that the frame is not of the specified type or that the data has not been received completely. The multi-type frame identifier outputs a frame type match failure signal, sets T1 as the new frame type determination initial time, and executes step 4.

[0064] Step 4: The multi-type frame identifier updates the frame type decision interval.

[0065] The multi-type frame identifier defines a new frame type determination interval [T1, T1+T] based on the new frame type determination initial time. Since the interval [T1, T0+T] has already been scanned and the peak position is T1, if the sender sends a frame of this type, the next peak position cannot be in the interval [T1, T0+T]. Therefore, the multi-type frame identifier only needs to scan the interval [T0+T, T1+T].

[0066] Step 5: The multi-type frame identifier searches for the maximum value in the partial frame type decision interval.

[0067] The multi-type frame identifier selects the maximum value within the frame type decision interval [T0+T, T1+T], assuming that the maximum value in the interval is located at T2.

[0068] Step 6: The multi-type frame identifier determines the position of the maximum value in the interval.

[0069] After obtaining the maximum value of the current frame type decision interval, the multi-type frame identifier determines whether the maximum value position meets the current frame type decision constraint. There are two possible cases for the decision:

[0070] Successful frame type identification: If T2 is located at T1+T within the frame type determination interval, the distance between the two assumed correlation peaks is equal to the length set by the multi-type frame identifier. Therefore, T1 represents the first correlation peak, and T2 (T1+T) represents the second correlation peak. Therefore, the received signal can be determined to be a frame of that type. The multi-type frame identifier outputs a frame type match success signal, sets the next moment as a new frame type determination initial moment, establishes a new frame type determination interval based on the new frame type determination initial moment, and executes step 2.

[0071] Frame type identification failure: If T2 is not at T1+T within the frame type decision interval, the distance between the two assumed correlation peaks is not equal to the length set by the multi-type frame identifier. Therefore, T1 cannot be the true first correlation peak, while T2 may be the first correlation peak. Therefore, it can be determined that the frame is not of that type or that complete data has been received. The multi-type frame identifier outputs a frame type match failure signal and updates the first correlation peak position register T1, assigning it the value of T2. This means that T2 is the starting point T1 of the next decision interval, and the process proceeds to step 4.

Claims

1. A device for multi-type frame recognition and judgment suitable for meteor trail communication, comprising a digital down-converter, a low-pass filter, and a data memory connected in sequence, for performing front-end processing on the obtained baseband signal; characterized in that: Also includes a matched filter, a frame type identifier and a frame type decision device; The received intermediate frequency signal is sampled, down-converted and low-pass filtered to obtain a complex baseband signal, which is then fed into a matched filter by the demodulator. Correlation is performed between the received signal and the local frame header sequence in a matched filter to estimate the position of the frame header during transmission and output a correlation peak indicating the position of the frame header in the complex baseband signal. The frame type identifier determines the spacing between frame headers by the distance between two correlation peaks, and outputs a frame type identification success signal when the frame header spacing meets the set distance; the frame type determiner determines the type of the currently received frame based on the frame type identification signal output by the frame identifier; when the frame type identifier outputs the frame type identification success signal, the frame type determiner outputs the information used for subsequent processing of the type of frame and resets the working status of all frame type determiners.

2. The device for multi-type frame recognition and judgment suitable for meteor trail communication according to claim 1, characterized in that: The frame type identifier is provided with at least one or more, and multiple frame type identifiers are connected in parallel; the difference between multiple frame type identifiers is that the lengths of their frame type decision intervals are different; both ends of each frame type identifier are respectively connected to the matching filter and the frame type determiner.

3. A method for multi-type frame recognition and judgment applicable to meteor trail communication, implemented by the device for multi-type frame recognition and judgment applicable to meteor trail communication according to claim 1 or 2, characterized in that: The specific steps are as follows: Step 1: The transmitter inserts a frame header before and after the data segment of the baseband signal. The distance between the two frame headers is the data segment length T. The lengths of the data segments of different frames are different, and the two frame headers are two identical sequences. Step 2: The matched filter at the receiving end works continuously to calculate the received data; Step 3: The frame type identifier sets the initial time of frame type determination to T0. Step 4: The frame type identifier used to identify the signal sent in step 1 has a decision interval of (T0, T0+T]; the frame type identifier searches for the highest peak within the range of (T0, T0+T], and the location of the highest peak is T1. The decision intervals of other frame type identifiers also start at T0, and the length of the decision interval is determined by the length of the required identification frame data segment. The highest peak is searched within each of their decision intervals, and the location of the highest peak within each of their decision intervals is called T1. In step 5, each frame type identifier determines whether the position of T1 within its decision interval satisfies a certain frame type decision constraint. If the position of T1 does not satisfy the corresponding frame type decision constraint, proceed to step 6. If the position of T1 satisfies the corresponding frame type decision constraint, proceed to step 7 with T1 as the correlation peak. Step 6: If the frame type identification fails, the initial time T1 of the next frame type determination is used as T0, and steps 4 to 5 are repeated; Step 7: If the frame type is successfully identified, the frame type decision information is output for subsequent signal processing; and the initial time T1 of the next frame type decision is used as T0, and steps 4 to 5 are repeated.

4. The method for multi-type frame recognition and judgment suitable for meteor trail communication according to claim 3, characterized in that: Whether the position of the correlation peak satisfies the decision constraint of a certain frame type is as follows: if the position of the correlation peak is at the end of the frame type decision interval to which it belongs, it is a successful decision; if the position of the correlation peak is not at the end of the frame type decision interval to which it belongs, it is a failed decision.

5. The method for identifying and judging multiple types of frames suitable for meteor trail communication according to claim 3, characterized in that: The frame type identifier compares the distance between the two frame headers with the length of their decision interval. When the frame header distance is equal to the length of the decision interval, the frame type identifier considers that the corresponding type of frame has been received; otherwise, it considers that the frame of this type has not been received.

6. A method for identifying and judging multiple types of frames suitable for meteor trail communication according to claim 3, characterized in that The frame type identifier first sets the initial time and interval for frame type determination; searches for the maximum value within the frame type determination interval, and determines whether the position of the maximum value within the interval can be used as a correlation peak: when the distance between the maximum values ​​in two adjacent intervals is equal to the frame length set by this frame type identifier, the corresponding frame type identifier outputs a successful recognition flag; otherwise, the frame type identifier outputs a unsuccessful recognition flag; finally, the initial time and interval for frame type determination are updated.

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