A short wave communication frequency selection method based on breadth first tree search and a corresponding system

Abstract

The application discloses a short-wave communication frequency selection method based on breadth-first tree search and a corresponding system to improve the frequency selection efficiency and accuracy. The method comprises the following steps: collecting a frequency through an LQA database and a long-term prediction model; selecting a frequency according to communication quality as a tree root node, and sequentially taking the frequency as a left leaf node if the frequency is less than the root node or as a right leaf node if the frequency is greater than the root node to generate a search tree; splitting the entire frequency interval into multiple intervals by the frequency, selecting a frequency point with the optimal communication quality and a communication quality value greater than a quality threshold in the longest interval, and continuing to generate the search tree; if there is no used frequency, selecting a frequency point with the minimum interference through spectrum sensing technology to continue to generate the search tree until a frequency is selected; and estimating an available frequency band by using a long-term prediction model, continuing to generate the search tree on the frequency band, and selecting a frequency until a frequency is selected. Finally, the number of nodes of the search tree is + +. The short-wave communication frequency selection is performed based on the search tree.

Description

Technical Field

[0001] This invention relates to the field of communications, and in particular to a shortwave communication frequency selection method and corresponding system based on breadth-first tree search. Background Technology

[0002] The shortwave bandwidth is approximately 2-30MHz, with each communication channel occupying a 3kHz bandwidth. The entire band can be roughly divided into 9333 usable carrier frequencies. When a shortwave radio is powered on, both the transmitter and receiver need to confirm the communication frequency. However, the actual electromagnetic environment is very complex, and the communication quality of available frequencies is constantly changing. Static allocation cannot cope with channel variations, and blindly trying different frequencies is inefficient. Therefore, an efficient and rapid frequency selection method is needed to meet the communication requirements of modern shortwave radios. (Refer to...) Figure 1 As shown.

[0003] Existing shortwave communication frequency selection methods, both domestically and internationally, fall into three categories: real-time frequency detection, short-term frequency prediction, and long-term frequency prediction. Real-time frequency detection requires hardware systems for frequency updates and detection. Short-term frequency prediction utilizes short-term frequency patterns, employing neural networks and machine learning to uncover implicit relationships within the data to predict the current frequency. Long-term frequency prediction uses empirical formulas, calculating the highest available frequency by setting model parameters. Real-time frequency detection requires additional detection systems, long-term frequency prediction has low accuracy, and short-term prediction tends towards intelligent prediction.

[0004] The development of fourth-generation shortwave communication systems has introduced intelligent communication technology and cognitive radio, utilizing intelligent learning, intelligent spectrum sensing, and adaptive adjustment to optimize frequency selection for shortwave communication. Influenced by changes in the natural environment and frequent human activities, shortwave communication data is constantly being generated, updated, and changed. This data is closely correlated across time, space, and frequency dimensions. How to utilize this data for data mining to select efficient and real-time shortwave communication frequencies is a key focus of current research.

[0005] In shortwave environments, the main machine learning strategies include neural network-based learning, statistical learning, and reinforcement learning. Currently, frequency selection research mainly focuses on two aspects: ① how to select the best channel or frequency from historical data, and ② how to effectively balance "exploitation-exploration". Summary of the Invention

[0006] This invention provides a shortwave communication frequency selection method and corresponding system based on breadth-first tree search, in order to improve frequency selection efficiency and accuracy.

[0007] The shortwave communication frequency selection method based on breadth-first tree search according to embodiments of the present invention includes: Collected during communication The historical frequencies are arranged in ascending order of their communication frequency values. ; First, the communication quality is ranked from best to worst. Sort the historical frequencies and select the top ones. frequency ,by As the root node, take in sequence ,like Then As The left leaf, otherwise As The right leaf, and so on, traversing to the next leaf. To generate a breadth-first search tree; Then, the data used to generate the breadth-first search tree Each frequency point will be the The data is divided into multiple intervals of varying lengths. The longest interval is selected and adaptively adjusted. Within the adjusted interval, the data is then processed... The process begins by selecting the frequency point with the best communication quality and a quality value greater than the quality threshold, and then generating a breadth-first search tree. If no historical frequency exists in the interval, a frequency point with minimal interference is randomly selected using spectrum sensing technology, and the breadth-first search tree is generated again. This process is repeated until a frequency point with minimal interference is selected. One frequency; at last, The frequency point will be the The frequency bands are divided into multiple intervals, and available frequency bands are estimated using a long-term prediction model. The breadth-first search tree is then generated using the method described above until a frequency band is selected. One frequency; Shortwave communication frequency selection is performed based on the breadth-first search tree, wherein the number of nodes in the breadth-first search tree is: ; The collection The historical frequencies include: Based on the current communication time, the locations of the transmitting and receiving parties, or the radio station number, LQA samples are screened from the historical shortwave communication database to determine... A historical frequency.

[0008] According to some embodiments of the present invention, the step of screening LQA samples from a historical shortwave communication database based on the current communication time, the locations of the transmitting and receiving parties, or the radio station number, in order to determine... Historical frequencies, including: During the communication process, Line Quality Analysis (LQA) samples of shortwave communication are collected and stored in the shortwave communication database; the data information in the LQA samples includes the location of the transmitting and receiving parties, communication time, communication frequency, communication quality, and radio station number; Based on the current hour , The shortwave communication database is used to filter out time slots within a preset number of days corresponding to the radio stations of both the transmitting and receiving parties. LQA sample screening is performed within the interval.

[0009] According to some embodiments of the present invention, q takes the value of 1 or 2.

[0010] According to some embodiments of the present invention, the long-term prediction model is the ITU-R P533 model or the ITS VOACAP model.

[0011] According to some embodiments of the present invention, the communication quality is comprehensively evaluated based on the frequency availability probability, the transmit / receive signal-to-noise ratio, and the interference intensity index.

[0012] According to some embodiments of the present invention, the adaptive adjustment includes: For the interval with the longest interval length Adjusted range for: ， In the formula, .

[0013] According to some embodiments of the present invention, the shortwave communication frequency selection based on the breadth-first search tree includes: Generate the breadth-first search tree and select frequencies according to the generation order of the nodes in the breadth-first search tree.

[0014] According to some embodiments of the present invention, in the method of generating the breadth-first search tree and selecting frequencies according to the generation order of the nodes of the breadth-first search tree, after generating the breadth-first search tree, the frequency selection is performed using... probability exchange and ， , Take 0.1 or 0.2.

[0015] This invention also proposes a shortwave communication frequency selection system based on breadth-first search tree search, including: a long-term prediction module, an LQA database, a spectrum sensing module, and a frequency selection recommendation module based on the search tree. The frequency selection recommendation module based on the search tree is used for: During communication, LQA samples are filtered from the historical shortwave communication database based on the current time, the locations of the transmitting and receiving parties, or the radio station number, to obtain... One historical frequency; Arranged in ascending order of communication frequency values. ; First, the communication quality is ranked from best to worst. Sort the historical frequencies and select the top ones. frequency Generate a breadth-first search tree ， by As the root node, take in sequence ,like Then As The left leaf, otherwise As The right leaf, and so on, traversing to the next leaf. To generate a breadth-first search tree; Then, the data used to generate the breadth-first search tree Each frequency point will be the Divide the data into multiple intervals, select the interval with the longest length, and adaptively adjust it; within the adjusted interval, from... The frequency point with the best communication quality and a communication quality value greater than the quality threshold is selected, and a breadth-first search tree is generated. If no historical frequency exists in the interval, the frequency point with the least interference is randomly selected by the spectrum sensing module, and a breadth-first search tree is generated. This step is repeated until a frequency point with the best communication quality and a communication quality value greater than the quality threshold is selected. One frequency; at last, Each frequency point will be the The frequency bands are divided into multiple intervals, and available frequency bands are estimated using a long-term prediction model. The breadth-first search tree is then generated using the method described above until a frequency band is selected. One frequency; Shortwave communication frequency selection is performed based on the breadth-first search tree, wherein the number of nodes in the breadth-first search tree is: .

[0016] By employing the embodiments of the present invention, the efficiency of "exploitation-exploration" is effectively balanced by making full use of both historical data and long-term prediction search trees, which makes up for the deficiencies of prediction systems in terms of real-time performance and accuracy, and also avoids the algorithm from getting stuck in a suboptimal solution or even an unusable state; combined with spectrum sensing capabilities, frequencies with less interference are preferred.

[0017] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0018] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of the embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings: Figure 1 This is a schematic diagram of the frequency detection process for a shortwave radio station; Figure 2 This is a schematic diagram of the N frequency nodes arranged from smallest to largest in an embodiment of the present invention; Figure 3 This is an embodiment of the present invention. A schematic diagram illustrating the breadth-first search tree generation process for each node; Figure 4 This is an embodiment of the present invention. , A diagram illustrating the generation of a breadth-first search tree based on the longest interval; Figure 5 This is a schematic diagram of the composition of a shortwave communication frequency selection system based on breadth-first tree search according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the input-output parameter relationship of the ITU-R P533 prediction model in an embodiment of the present invention; Figure 7 This is a schematic diagram of interference identification based on spectrum sensing in an embodiment of the present invention. Detailed Implementation

[0019] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art. Furthermore, in some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0020] The shortwave communication frequency selection method based on breadth-first tree search according to embodiments of the present invention includes: Collected during communication The historical frequencies are arranged in ascending order of their communication frequency values. ; First, the communication quality is ranked from best to worst. Sort the historical frequencies and select the top ones. frequency ,by As the root node, take in sequence ,like ,but As The left leaf, otherwise As The right leaf, and so on, traversing to the next leaf. To generate a breadth-first search tree; Then, the data used to generate the breadth-first search tree Each frequency point will be the The system is divided into multiple intervals of varying lengths. The longest interval is selected and adaptively adjusted. Within the adjusted interval, the frequency with the best communication quality (above a quality threshold) is chosen from the remaining historical frequencies, and a breadth-first search tree is generated. If no historical frequency exists in the interval, a frequency with minimal interference is randomly selected using spectrum sensing technology, and a breadth-first search tree is generated again. This process is repeated until a frequency with the best communication quality is selected. One frequency; Each frequency point will be the The frequency bands are divided into multiple intervals. Finally, a long-term prediction model is used to estimate the available frequency bands. The breadth-first search tree is then generated using the method described above until the selected frequency bands are found. One frequency; Shortwave communication frequency selection is performed based on the breadth-first search tree, wherein the number of nodes in the breadth-first search tree is: ; The collection The frequencies include: Based on the current communication time, the locations of the transmitting and receiving parties, or the radio station number, LQA samples are screened from the historical shortwave communication database to determine... The long-term prediction model takes into account historical frequencies. The input information includes transmit / receive location, transmit / receive antenna type, and communication environment information; the output is available communication frequency band information.

[0021] By employing the embodiments of the present invention, the efficiency of "exploitation-exploration" is effectively balanced by making full use of both historical data and long-term prediction search trees, which makes up for the deficiencies of the prediction system in terms of real-time performance and accuracy, and also avoids the algorithm from getting stuck in a suboptimal solution or even an unusable state; combined with spectrum sensing capabilities, frequencies with less interference are preferred.

[0022] Based on the above embodiments, further variant embodiments are proposed. It should be noted that, in order to keep the description brief, only the differences from the above embodiments are described in each variant embodiment.

[0023] If the transmitting and receiving parties cannot obtain the radio station coordinates, nor can they determine the approximate passable frequency band range through other prior information, or if the historical frequency set deviates significantly from the passable frequency band of the long-term prediction model, then the long-term prediction module is unusable. In this case, the entire shortwave band of 9333 channels is used as the generation range for the search tree.

[0024] If both the transmitter and receiver are equipped with GPS / BD modules, they can obtain the radio station coordinates, and the historical frequency set coincides with the passable frequency band of the long-term prediction model. Then, the union of the two is used as the generation interval of the search tree.

[0025] According to some embodiments of the present invention, the step of screening LQA samples from a historical shortwave communication database based on the current communication time, the locations of the transmitting and receiving parties, or the radio station number, in order to determine... Historical frequencies, including: During the communication process, Line Quality Analysis (LQA) samples of shortwave communication are collected and stored in the shortwave communication database; the data information in the LQA samples includes the location of the transmitting and receiving parties, communication time, communication frequency, communication quality, and radio station number; Based on the current hour , The shortwave communication database is used to filter out time slots within a preset number of days corresponding to the radio stations of both the transmitting and receiving parties. LQA sample screening is performed within the interval.

[0026] Here, q can be either 1 or 2. When there are many samples, you can use a value of 1. If frequency selection is still not completed after using a value of 1, you can try using a value of 2 to continue frequency selection.

[0027] According to some embodiments of the present invention, the long-term prediction model is the ITU-R P533 model or the ITS VOACAP model.

[0028] According to some embodiments of the present invention, the communication quality is comprehensively evaluated based on the frequency availability probability, the transmit / receive signal-to-noise ratio, and the interference intensity index.

[0029] According to some embodiments of the present invention, the adaptive adjustment includes: For the interval with the longest interval length Adjusted range for: ， In the formula, .

[0030] It should be noted that in the embodiments of the present invention, the frequency refers to the carrier frequency, which can also be understood as the channel. That is, the available frequency range of the shortwave band is divided into available channels and their carrier frequencies according to the channel.

[0031] According to some embodiments of the present invention, the shortwave communication frequency selection based on the breadth-first search tree includes: Generate the breadth-first search tree and select frequencies according to the generation order of the nodes in the breadth-first search tree.

[0032] According to some embodiments of the present invention, in the method of generating the breadth-first search tree and selecting frequencies according to the generation order of the nodes of the breadth-first search tree, after generating the breadth-first search tree, the frequency selection is performed using... probability exchange and , , Take 0.1 or 0.2.

[0033] This invention also proposes a shortwave communication frequency selection system based on breadth-first search tree search, including: a long-term prediction module, an LQA database, a spectrum sensing module, and a frequency selection recommendation module based on the search tree. The frequency selection recommendation module based on the search tree is used for: Collected during communication For each frequency, LQA samples are preferentially selected from the historical shortwave communication database based on the current time, the location of the transmitting and receiving parties, or the radio station number; the input information of the long-term prediction model includes the transmitting and receiving locations, the type of transmitting and receiving antennas, and the communication environment information, and the output is the available communication frequency band information; Arranged in ascending order of communication frequency values. ; First, the communication quality is ranked from best to worst. Sort the frequencies and select the top ones. frequency Generate a search tree, in order to As the root node, take in sequence ,like ,but As The left leaf, otherwise As The right leaf, and so on, traversing to the next leaf. To generate a breadth-first search tree; Then, the frequency points used to generate the breadth-first search tree will be... The data is divided into multiple intervals of different lengths. The interval with the longest length is selected and adaptively adjusted. Within the adjusted interval, the data is then... The frequency point with the best communication quality and a communication quality value greater than the quality threshold is selected, and a breadth-first search tree is generated. If no historical frequency exists in the interval, the frequency point with the least interference is randomly selected by the spectrum sensing module, and a breadth-first search tree is generated. This step is repeated until a frequency point with the best communication quality and a communication quality value greater than the quality threshold is selected. One frequency; Finally, the available frequency bands are estimated using a long-term prediction model, and the breadth-first search tree is generated using the method described above until a frequency band is selected. One frequency; Shortwave communication frequency selection is performed based on the breadth-first search tree.

[0034] The shortwave communication frequency selection method based on breadth-first tree search according to the present invention is described in detail below with reference to the accompanying drawings and a specific embodiment. It is important to emphasize that the following description is merely exemplary and should not be construed as a specific limitation of the present invention.

[0035] This invention proposes a simple and easy-to-implement shortwave communication frequency selection method based on breadth-first search. This method fully utilizes Link Quality Analysis (LQA) information from historical communication data and combines it with a long-term prediction model to identify available communication frequency bands. Then, it uses a breadth-first search tree to quickly search for available frequencies, effectively balancing the efficiency of "utilization-exploration" and avoiding suboptimal or unavailable solutions. Furthermore, it uses as few frequencies as possible to cover communication bands, reducing spectrum resource waste. The action values ​​and policy tables of the probabilistic model are updated incrementally to adapt to the complex and ever-changing shortwave communication environment.

[0036] Specifically, the implementation steps of the shortwave communication frequency selection method based on breadth-first search tree search include: A Level Quality Assurance (LQA) database will be constructed. LQA data for shortwave communication includes (but is not limited to) the coordinates of both transmitting and receiving stations, communication time, communication frequency, and signal-to-noise ratio (SNR). The database table fields are roughly as shown in Table 1. If more LQA samples of shortwave communication over a longer period are collected nationwide, the frequency measurement information in the database will become increasingly rich.

[0037] Table 1 Database Field Sample Assuming the current number of hours is ( ), , from the LQA database, filter out the coordinates of the sender and receiver corresponding to the coordinates of the sender and receiver in the current month nearby Hours LQA samples for shortwave communication frequencies That is, the sample time is Within the interval. Then, take their frequency values ​​and arrange them in ascending order as follows: , refer to Figure 2 As shown.

[0038] Initial sample frequency range Interval length According to the evaluation function For each sample, assess the LQA and calculate its action value: ， in, It can be a comprehensive evaluation function of indicators such as frequency availability probability, transmit / receive signal-to-noise ratio, and interference intensity.

[0039] from Select the top performers based on their action value (also known as communication quality). ( ) frequencies ,by As the root node of the tree ,by ( Generate a breadth-first search tree.

[0040] The specific method is as follows: take in sequence ,if Then traverse The left subtree, otherwise traverse The right subtree, up to the leaf node. ( ).if but As The left leaf, otherwise As The right leaf, such as Figure 3 As shown.

[0041] For the remaining Select a sample The process of a node is as follows: The nodes used to generate the tree divide the entire interval into multiple intervals. Let's assume the first interval is... ( ) nodes The interval is And it is the longest of all intervals, with a length of . Then in Select the best frequency within the interval as : ， ， in, This indicates rounding down to the nearest integer.

[0042] If in the interval There are no available historical sample frequencies, or the historical sample evaluation results are of poor quality. Then, using spectrum sensing technology, a frequency with the least interference is randomly selected from the spectrum sensing results as the first frequency. Each node is selected. This process is repeated until a node is chosen. After selecting all frequencies or valid historical sample frequencies, a breadth-first search tree based on historical data is finally obtained, as shown in the reference. Figure 4 As shown. From the perspective of the tree generation process, the previous... The frequency that received the best rating was the "utilization" frequency, followed by... The frequency covers the entire The frequency of "exploration" within a range.

[0043] when When the value is 1, if there are no valid LQA samples in the database (i.e. If so, try again. Take 2. When When taking option 2, if no valid LQA samples exist in the database, the available frequency band range is predicted using the following method: Case 1: If the transmitting and receiving parties cannot obtain the radio station coordinates, nor can they determine the approximate passable frequency band range through other prior information, or if the historical frequency set deviates significantly from the passable frequency band of the long-term prediction model, then the entire shortwave band will be used as the initial range. .

[0044] Case 2: If both the transmitter and receiver are equipped with GPS / BD modules to obtain the radio station coordinates, and the historical frequency set overlaps with the passable frequency bands of the long-term prediction model, then the union of the two is used as the initial interval. .

[0045] In this method, N historical frequency samples are first selected from the database, based on the previous... Generate a breadth-first search tree based on the frequency of the highest-rated nodes, and then filter the remaining nodes using the longest interval method. Each frequency point is used, and finally, the longest interval method is applied to generate more nodes in the long-term prediction model. Each frequency point.

[0046] Furthermore, to increase randomness, a randomization strategy is set: When the number of nodes in the search tree At that time, with probability exchange and ( ), It can be 0.1 or 0.2; Once the calling radio receives a link establishment confirmation signal, it can be considered that a usable frequency has been found. At this point, the calling radio can choose to stop probing the remaining frequencies or continue probing to obtain more usable frequencies. After a certain number of probing attempts, the search will stop. The choice of which to pursue depends on the radio's business needs.

[0047] for Each detection frequency per hour Update its action value function: ， ， in, For detection frequency The sample count.

[0048] The method of this invention has the following advantages: ① Priority detection before First, a good frequency is selected, and then a breadth-first sampling method is used to group historical samples, similar to the binary search approach. This fully leverages the correlation and accuracy of historical communication data while reducing the overhead of frequency detection. Second, real-time detection and long-term prediction models are integrated. A breadth-first search tree is used to detect available frequencies in a large state space, and an incremental approach is used to quickly evaluate action values ​​and policy tables. By combining historical data and long-term prediction with two types of breadth-first search trees, the efficiency of "exploitation-exploration" is effectively balanced, compensating for the shortcomings of the prediction system in terms of real-time performance and accuracy, and preventing the algorithm from getting stuck in suboptimal or even unusable states. Third, frequency with less interference is selected by combining spectrum sensing capabilities.

[0049] Reference Figure 5 As shown, this embodiment of the invention also proposes a shortwave communication frequency selection system based on breadth-first search tree, including: frequency management, long-term prediction module, LQA database, spectrum sensing module and frequency selection recommendation module based on breadth-first search tree.

[0050] The long-term forecasting module estimates available communication frequency bands using the ITU-R P533 standard model, or alternatively, the ITS VOACAP model. The LQA database module's main function is to save, statistically analyze, update, delete, or filter LQA sample data from historical communication processes. The frequency selection recommendation module uses a breadth-first search based on BFTS to find the optimal frequency or frequency set and recommends frequencies for use by shortwave communication systems.

[0051] When historical communication data is unavailable in the database, the long-term forecasting module uses the long-term prediction function of the P533 model as a reference. Alternatively, the ITS VOACAP forecasting model can also be used. P533 provides long-term forecasting methods for the highest and lowest available frequencies, such as... Figure 6 As shown. The shortwave band experiences significant interference, largely from broadcasts or other shortwave radio signals. This interference impacts shortwave communication quality; therefore, frequency selection must avoid frequencies with high interference. Fourth-generation shortwave radios possess spectrum sensing capabilities, allowing them to receive signals across the entire shortwave band and determine the interference intensity at each frequency. Based on this, the frequency selection module can preferentially select frequencies with less interference, such as… Figure 7 As shown.

[0052] LQA data for shortwave communication includes (but is not limited to) the coordinates of the transmitting and receiving stations, communication time, communication frequency, and signal-to-noise ratio. The database table fields are roughly as shown in Table 1 (REF _Ref201222781 \h \* MERGEFORMAT). If more LQA samples of shortwave communication over a longer period are collected nationwide, the frequency measurement information in the database will become increasingly rich.

[0053] It should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0054] It should be noted that any content not described in detail in this specification is common knowledge to those skilled in the art.

Claims

1. A shortwave communication frequency selection method based on breadth-first search tree search, characterized in that, include: Collected during communication The historical frequencies are arranged in ascending order of their communication frequency values. ; The following are ordered from best to worst communication quality: Sort the historical frequencies and select the top ones. frequency ,by As the root node, take in sequence ,like Then As The left leaf, otherwise As The right leaf, and so on, traversing to the next leaf. To generate a breadth-first search tree; Each frequency point will be the The system is divided into multiple intervals of different lengths. The interval with the longest length is selected and adaptively adjusted. In the adjusted interval, the frequency point with the best communication quality and a communication quality value greater than the quality threshold is selected from the remaining historical frequencies, and a breadth-first search tree is generated. If there is no historical frequency in the interval, a frequency point with the least interference is randomly selected through spectrum sensing technology to continue generating a breadth-first search tree. Repeat this step until a selection is made. One frequency; Each frequency point will be the The frequency bands are divided into multiple intervals, and available frequency bands are estimated using a long-term prediction model. The longest interval method is then used to generate a breadth-first search tree until a frequency band is selected. One frequency; Shortwave communication frequency selection is performed based on the breadth-first search tree, wherein the number of nodes in the breadth-first search tree is: ; The collection The historical frequencies include: Based on the current communication time, the locations of the transmitting and receiving parties, or the radio station number, LQA samples are screened from the historical shortwave communication database to determine... A historical frequency.

2. The method as described in claim 1, characterized in that, The process involves filtering LQA samples from a historical shortwave communication database based on the current communication time, the locations of both the transmitter and receiver, or the radio station number, to determine... Historical frequencies, including: During the communication process, Line Quality Analysis (LQA) samples of shortwave communication are collected and stored in the shortwave communication database; the data information in the LQA samples includes the location of the transmitting and receiving parties, communication time, communication frequency, communication quality, and radio station number; Based on the current hour , The shortwave communication database is used to filter out time slots within a preset number of days corresponding to the radio stations of both the transmitting and receiving parties. LQA sample screening is performed within the interval; q can take the value 1 or 2.

3. The method as described in claim 1, characterized in that, The long-term forecasting model is either the ITU-R P533 model or the ITSVOACAP model.

4. The method as described in claim 1, characterized in that, The communication quality is comprehensively evaluated based on the probability of frequency availability, the signal-to-noise ratio, and the interference intensity.

5. The method as described in claim 1, characterized in that, The adaptive adjustments include: For the interval with the longest interval length Adjusted range for: ， In the formula, .

6. The method as described in claim 1, characterized in that, The shortwave communication frequency selection based on the breadth-first search tree includes: Generate the breadth-first search tree and select frequencies according to the generation order of the nodes in the breadth-first search tree.

7. The method as described in claim 6, characterized in that, In the method of generating the breadth-first search tree and selecting frequencies according to the generation order of the breadth-first search tree nodes, after generating the breadth-first search tree, the frequency selection is performed using... probability exchange and , , Take 0.1 or 0.

2.

8. A shortwave communication frequency selection system based on breadth-first tree search, characterized in that, include: Long-term prediction module, LQA database, spectrum sensing module, and frequency selection recommendation module based on search tree; The frequency selection recommendation module based on the search tree is used for: During communication, LQA samples are filtered from the historical shortwave communication database based on the current time, the locations of the transmitting and receiving parties, or the radio station number, to obtain... One historical frequency; Arranged in ascending order of communication frequency values. ; The following are ordered from best to worst communication quality: Sort the historical frequencies and select the top ones. frequency ,by As the root node, take in sequence ,like Then As The left leaf, otherwise As The right leaf, and so on, traversing to the next leaf. To generate a breadth-first search tree; Each frequency point will be the The system is divided into multiple intervals, and the interval with the longest interval is selected and adaptively adjusted. In the adjusted interval, the frequency point with the best communication quality and a communication quality value greater than the quality threshold is selected from the remaining historical frequencies, and a breadth-first search tree is generated. If there is no historical frequency in the interval, the frequency point with the least interference is randomly selected through the spectrum sensing module to continue generating a breadth-first search tree. This step is repeated until M2 frequencies are selected. Each frequency point will be the The frequency bands are divided into multiple intervals, and available frequency bands are estimated using a long-term prediction model. The longest interval method is then used to generate a breadth-first search tree until a frequency band is selected. One frequency; Shortwave communication frequency selection is performed based on the breadth-first search tree, wherein the number of nodes in the breadth-first search tree is: .

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