CN118432698B - Time division duplex communication method suitable for satellite communication - Google Patents
Time division duplex communication method suitable for satellite communication Download PDFInfo
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- CN118432698B CN118432698B CN202410896061.4A CN202410896061A CN118432698B CN 118432698 B CN118432698 B CN 118432698B CN 202410896061 A CN202410896061 A CN 202410896061A CN 118432698 B CN118432698 B CN 118432698B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/1851—Systems using a satellite or space-based relay
- H04B7/18513—Transmission in a satellite or space-based system
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/18578—Satellite systems for providing broadband data service to individual earth stations
- H04B7/18582—Arrangements for data linking, i.e. for data framing, for error recovery, for multiple access
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- H—ELECTRICITY
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- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/14—Two-way operation using the same type of signal, i.e. duplex
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Abstract
The invention discloses a time division duplex communication method suitable for satellite communication, which comprises the steps of obtaining a coordination world time signal, and determining the coordination world time of a preset timing time slot sending moment based on the coordination world time signal; the master station respectively constructs a forward frame structure and a reverse frame structure, acquires forward frame data based on coordinated universal time, fills the forward frame data into the forward frame structure, and forms a forward frame; the end station receives the forward frame and analyzes the forward frame; based on the analysis result, reverse frame data is acquired, and is filled into a reverse frame structure to form a reverse frame; the primary station receives the reverse frame and adjusts the broadcast time slots in the forward frame based on the control time slots in the reverse frame. The satellite master station is not restricted, and by combining the time synchronization technology, dynamic resource allocation and real-time monitoring and adjustment, the invention realizes that the frame length of the system is not limited by the satellite-to-ground distance and allows the flexible variation of the number of users, and has higher convenience.
Description
Technical Field
The invention belongs to the field of satellite communication, and discloses a time division duplex communication method suitable for satellite communication.
Background
With the increasing demand for communication-in-motion antennas, low-profile communication-in-motion antennas, mainly flat panel arrays and phased array antennas, are presented in order to further reduce the profile of the antennas. From the viewpoints of saving cost, reducing equipment power consumption and the like, the terminal faces the requirement of receiving and transmitting coplanarity, and in this case, the terminal cannot realize simultaneous receiving and transmitting.
Starting from the third generation (3G) terrestrial mobile communication system, time Division Duplex (TDD) mode has become one of the dominant modes of operation. Existing schemes for time division duplexing all face this problem: the length of the physical frame structure is in strong correlation with the satellite-to-ground distance, namely, the frame length is set to be the electromagnetic wave satellite-to-ground transmission time or the integral multiple of the satellite-to-ground transmission time, so that the frame length of the system is limited by the satellite-to-ground distance, the satellite master station is restrained, and the flexible variation of the number of users is limited.
Disclosure of Invention
The invention aims to: a time division duplex communication method suitable for satellite communication is provided to solve the above problems existing in the prior art.
The technical scheme is as follows: a time division duplex communication method suitable for satellite communication, comprising the steps of:
S1, acquiring a coordination world time signal, and determining coordination world time of a preset timing time slot sending moment based on the coordination world time signal;
S2, respectively constructing a forward frame structure and a reverse frame structure by the master station, acquiring forward frame data based on coordinated universal time, and filling the forward frame data into the forward frame structure to form a forward frame; the forward frame structure comprises a forward service time slot, a timing time slot and a broadcasting time slot; the reverse frame structure comprises a reverse service time slot, a control time slot and a login time slot;
S3, the end station receives the forward frame and analyzes the forward frame;
S4, based on the analysis result, reverse frame data are obtained, and are filled into a reverse frame structure to form a reverse frame;
S5, the master station receives the reverse frame, adjusts the broadcast time slot in the forward frame based on the control time slot in the reverse frame, and obtains the adjusted forward frame.
The beneficial effects are that: the satellite master station is not restricted, and by combining the time synchronization technology, dynamic resource allocation and real-time monitoring and adjustment, the invention realizes that the frame length of the system is not limited by the satellite-to-ground distance and allows the flexible variation of the number of users, and has higher convenience.
Drawings
FIG. 1 is a flow chart of the present invention.
Fig. 2 is a flowchart of step S1 of the present invention.
Fig. 3 is a schematic diagram of UTC time generation in the present invention.
FIG. 4 is a schematic diagram of UTC counts in accordance with the present invention.
Fig. 5 is a schematic diagram of cycle count based on a timing slot transmission period in the present invention.
Fig. 6 is a flowchart of step S2 of the present invention.
Fig. 7 is a schematic diagram of a radio frame structure according to the present invention.
Fig. 8 is a schematic diagram of UTC data population in the present invention.
FIG. 9 is a flow chart of the system operation according to an embodiment of the present invention.
Fig. 10 is a flowchart of step S3 of the present invention.
Fig. 11 is a flowchart of step S4 of the present invention.
Fig. 12 is a flowchart of step S5 of the present invention.
Fig. 13 is a schematic diagram of a system planning according to an embodiment of the present invention.
Detailed Description
As shown in fig. 1, the present application provides a time division duplex communication method suitable for satellite communication, comprising the following steps:
S1, acquiring a coordination world time signal, and determining coordination world time of a preset timing time slot sending moment based on the coordination world time signal;
S2, respectively constructing a forward frame structure and a reverse frame structure by the master station, acquiring forward frame data based on coordinated universal time, and filling the forward frame data into the forward frame structure to form a forward frame; the forward frame structure comprises a forward service time slot, a timing time slot and a broadcasting time slot; the reverse frame structure comprises a reverse service time slot, a control time slot and a login time slot;
S3, the end station receives the forward frame and analyzes the forward frame;
S4, based on the analysis result, reverse frame data are obtained, and are filled into a reverse frame structure to form a reverse frame;
S5, the master station receives the reverse frame, adjusts the broadcast time slot in the forward frame based on the control time slot in the reverse frame, and obtains the adjusted forward frame.
In this embodiment, by acquiring coordinated Universal Time (UTC) signals, the system implements a global unified time standard, and ensures time synchronization of each site in the system, so as to avoid communication collision and time slot overlapping; the structure of the forward frame and the reverse frame is constructed, the forward service time slot is used for transmitting user data, the timing time slot is used for synchronizing user equipment, and the broadcasting time slot is used for broadcasting system information, so that the structure effectively organizes communication resources and improves the flexibility and the efficiency of the system; the reverse service time slot is used for receiving user data, the control time slot is used for transmitting control information, the login time slot is used for accessing user equipment, and the division is helpful for improving the capacity and reliability of the system; filling the reverse frame structure by analyzing the forward frame, so as to ensure that the response data of the user is correctly organized and transmitted back to the master station; the master station adjusts the broadcast time slot in the forward frame according to the control time slot in the reverse frame, and the self-adaptive adjustment can improve the performance and the resource utilization rate of the system according to the actual communication requirement.
As shown in fig. 2, according to an aspect of the present application, step S1 is further:
S11, acquiring a second pulse signal and a day time signal through a GPS time service instrument, and recovering a coordinated universal time signal from the second pulse signal and the day time signal;
S12, determining the sending moment of a timing time slot according to a preset time slot schedule;
s13, based on the coordination world time signal, acquiring coordination world time of the timing time slot sending moment.
In a further embodiment, as shown in fig. 3, the satellite communication master station is provided with a GPS time service instrument, and can obtain pulse per second (1 PPS) and time of day (TOD) information, and the master station board card performs signal recovery, and recovers coordinated Universal Time (UTC) signals from the 1PPS and the TOD; the master station obtains the sending time of the timing time slot according to the time slot schedule table, and obtains the UTC time of the time.
As shown in fig. 4 to 5, by acquiring the UTC start signal, operations such as UTC recovery and counting are started, and a UTC count value is output; meanwhile, performing cycle counting according to a timing time slot transmission period, performing transmission period counting when a first valid UTC value is acquired, and pulling UTC_Ready (UTC Ready) high when the value of a counter is equal to the transmission period, wherein UTC_Ready is a signal or a flag for indicating whether the system is Ready to use in coordination world time; UTC_Ready is pulled low when it is detected that catch_over is high, where catch_over indicates the end of a capture process or cycle in data or signal processing. T in fig. 5 represents a UTC transmission period.
The present embodiment ensures time synchronization of all components in the system by retrieving the pulse-in-second signal and the time-of-day signal to recover the coordinated universal time signal, which allows the system to vary independent of the satellite-to-ground distance, because all time stamping is based on the uniform coordinated universal time. The preset time slot schedule can be adjusted according to actual needs instead of being fixed, so that the frame length can be dynamically adjusted according to the communication needs and the change of the satellite-to-ground distance.
As shown in fig. 6, according to an aspect of the present application, step S2 is further:
S21, respectively constructing a forward frame structure and a reverse frame structure by a master station, wherein the forward frame structure comprises a forward service time slot, a timing time slot and a broadcasting time slot; the reverse frame structure comprises a reverse service time slot, a control time slot and a login time slot;
s22, sending the coordinated universal time into a baseband generating module, generating timing time slot data through a modulation and coding mode, and filling the timing time slot data into the timing time slot;
s23, acquiring forward user data, generating forward service time slot data based on the forward user data, and filling the forward service time slot data into the forward service time slot;
S24, constructing a reverse time slot plan, generating broadcast time slot data based on the reverse time slot plan, and filling the broadcast time slot data into the broadcast time slot;
S25, forming a forward frame based on the timing time slot, the forward service time slot and the broadcast time slot after filling the data.
In a specific embodiment, as shown in fig. 7, the radio frame is divided into a forward frame and a reverse frame, both of which are composed of a plurality of slots. Because of unknowns of the geographic positions of the satellite terminals and differences of transmission distances between different terminals and satellites, the interior of a time slot is divided into a data segment and a protection segment, wherein the data segment is used for bearing service data, the protection segment is filled with invalid data and is used for resisting signal transmission influence caused by the differences of the transmission distances, and the initial position of the data segment in a single time slot is positioned at the position of the satellite terminal and shows a strong correlation.
Forward frames carrying data transmitted by the satellite communication master station to the end stations. There are two special slots in addition to the regular traffic slots, one being a timing slot and the other being a broadcast slot. Because of the time division system, the timing is a precondition, and the satellite master station transmits the current time to the satellite end stations distributed in various places through the timing time slot, so that the equipment at the receiving and transmitting ends of the system realizes timing synchronization. As shown in fig. 8, UTC time is sent to a baseband generating module and is signaled, UTC data is modulated and encoded by (QPSK, 1/2), the information bit length is 4032 bits, and the obtained UTC data is repeatedly padded during padding to form a timing slot. For broadcast slots, some system information is carried, such as when the end station should make a system login, request to reply to access the network, slot plan for the current system, etc.
In this embodiment, the satellite master station plays an absolute control role, for example, it performs configuration of frame structures according to the number of users, service types and service levels in the current system, and involves configuring the number of forward and reverse frame slots and the slot length of a single slot to finally form a required slot plan. As shown in fig. 9, the satellite master station first schedules a reverse slot plan, and the small station transmits signals only at a designated time and receives signals at other times; the master station decides that certain user data can be transmitted at the current moment according to the transmission distance and the reverse time slot plan.
After the master station receives that a certain time slot is filled, the master station judges whether the next time slot is filled with current user data or other user data; if the user data is the current user data, judging whether the transmission is allowed or not; in the case of other user data, the insertion of new users needs to be taken into account.
As shown in fig. 10, according to an aspect of the present application, step S3 is further:
S31, the end station receives the forward frame, analyzes the timing time slot in the forward frame and realizes time synchronization with the master station;
s32, analyzing a broadcast time slot in the forward frame, and determining a broadcast information detection window according to the timing time slot and the broadcast time slot;
s33, based on the broadcast information detection window and the broadcast time slot, acquiring a reverse time slot planning period and the login time of the terminal station for system network access;
s34, analyzing the forward service time slot in the forward frame, and carrying out parameter statistics on the user data in the forward service time slot.
In this embodiment, due to the existence of the system timing time slot, the satellite master station and the satellite end station realize time synchronization, that is, the forward frame and the reverse frame can be on the same time scale, so that the data content of the forward frame and the data content of the reverse frame at each moment can be controlled. Before the small station is started and is connected to the network, the information such as the symbol rate of the main station is acquired in other modes, and then the blind search stage is started. Acquiring a timing signal, performing time adjustment, and determining a broadcast information detection window according to the relation between the timing time slot and the broadcast time slot; detecting broadcast information, acquiring a reverse time slot planning period, and determining a login time slot and a control time slot; and sending a login request. Then entering a synchronization stage, analyzing the broadcast signals, and obtaining a reverse time slot plan of a small station of the user; and analyzing the forward service time slot to acquire the data required by the user.
As shown in fig. 11, according to an aspect of the present application, step S4 is further:
S41, generating login time slot data based on the login time of the system network access of the end station obtained through analysis, and filling the login time slot data into the login time slot;
S42, generating control time slot data based on the analysis result of the parameter statistics, and filling the control time slot data into the control time slot;
s43, acquiring reverse user data, generating reverse service time slot data based on the reverse user data, and filling the reverse service time slot data into a reverse service time slot;
s44, forming a reverse frame based on the login time slot, the control time slot and the reverse service time slot after filling data;
s45, transmitting the reverse frame to the master station according to the reverse time slot planning period.
In this embodiment, the reverse frame carries data transmitted from the satellite communication end station to the master station. There are two special time slots, one is a control time slot and the other is a login time slot, in addition to the traffic time slot of the current end station. When the end station receives the forward broadcast slot plan, it can learn the login time, if the end station needs to make system access, it will make login request in login slot. When the end station obtains the forward data, some parameter statistics such as communication quality, time-frequency offset and the like are performed, the statistics are fed back to the satellite communication master station through the control time slot, and the master station adjusts the time slot plan according to the feedback information of the end station.
As shown in fig. 12, according to an aspect of the present application, step S5 is further:
s51, the master station receives a reverse frame and monitors a control time slot in the reverse frame;
S52, judging whether the end station is online or not based on the monitoring result, and skipping the end station which is not online if the end station is not online; if online, go to step S53;
S53, analyzing a control time slot in a reverse Frame to obtain a parameter statistical result, adjusting a reverse time slot plan in a broadcast time slot of a forward Frame based on the parameter statistical result to ensure that forward reverse non-service time slots are not overlapped in time, and meeting that the forward Frame length and the reverse Frame length have the least common multiple, namely meeting M x Frame forward=N*Framebackward, wherein Frame forward represents the total duration occupied by a single forward Frame, frame backward represents the total duration occupied by a single reverse Frame, M, N respectively represents the number of forward frames and reverse frames, and obtaining an adjusted forward Frame;
and S54, the adjusted forward frame is sent to the end station.
In this embodiment, the master station may set the forward and reverse symbol rates, and the number of slots in the forward and reverse frame slot plan, so as to ensure that the small station can correctly receive the forward control information and normally access the network, and the following several requirements need to be met: as shown in fig. 13, m×frame forward=N*Framebackward needs to be satisfied, where M, N represents the number of forward frames and reverse frames, respectively, frame forward represents the total duration occupied by a single forward Frame, and Frame backward represents the total duration occupied by a single reverse Frame; the forward control time slot and the reverse control time slot of the forward non-business time slot are not overlapped in time. Monitoring the reverse control time slot to determine whether the small station is on line; and analyzing the control time slot in the reverse frame to obtain a parameter statistical result, and replacing the reverse time slot plan based on the parameter statistical result.
In this embodiment, the master station may flexibly manage the number of users by monitoring the control time slots in the reverse frame and adjusting based on the parameter statistics result, so as to allow the system to adapt to the change of the number of users while maintaining efficient communication.
The application combines time synchronization technology, dynamic resource allocation and real-time monitoring and adjustment, thus realizing flexibility of system frame length and adaptability to user number variation, and enabling the communication system to adapt to complex and changeable communication environment while maintaining high efficiency.
According to another aspect of the present application, step S53 is further:
s531, analyzing a control time slot in a reverse frame to obtain a parameter statistical result, wherein the parameter statistical result comprises the communication requirement and the priority of each terminal station;
S532, based on the result of parameter statistics, evaluating the current time slot allocation situation, and if the current allocation meets the requirement, keeping unchanged; if not, proceeding to step S533;
S533, calculating to obtain an optimal time slot allocation scheme by adopting an optimization algorithm based on the evaluation result; the optimization goal of the optimal time slot allocation scheme is to maximize the communication efficiency of the whole system, ensure that the forward and reverse non-service time slots are not overlapped in time, and meet the condition that the forward frame length and the reverse frame length have the least common multiple;
and S534, adjusting a reverse time slot plan in the broadcast time slot of the forward frame based on the optimal time slot allocation scheme to obtain an adjusted forward frame.
In the embodiment, by evaluating the communication requirement and the priority of each terminal station, the time slot allocation can be more fair, and meanwhile, the service quality is ensured, which is particularly important for satellite communication in a multi-user environment; the optimal time slot allocation scheme obtained by adopting the optimization algorithm can ensure that the communication efficiency of the whole system reaches the maximum. This not only increases the speed of data transmission but also reduces data retransmission due to slot collisions, thereby reducing delay and bandwidth waste.
In particular embodiments, a satellite communications network includes a master station and a plurality of end stations. The primary station is responsible for managing the transmission and reception of forward and reverse frames. Each end station has different communication requirements and priorities, which may change over time. The master station first parses the control slots in the reverse frame and gathers the communication needs and priority information for each end station. For example, end station a may require a high bandwidth for video transmission, while end station B may require only a low bandwidth for data transmission. The master station evaluates the current slot allocation. If the current allocation has satisfied the needs of all end stations, it remains unchanged. If the video transmission requirement of the end station A is not met, for example, the main station adopts an optimization algorithm, such as a genetic algorithm, to calculate an optimal time slot allocation scheme.
In a satellite communication network consisting of 10 end stations, time slots are allocated to the end stations to maximize communication efficiency, and genetic algorithms are used to find the optimal time slot allocation scheme. First initializing a population containing 100 possible slot allocation schemes, each scheme being an array containing 10 elements, each element representing a slot allocation of an end station; then defining a fitness function, wherein the fitness function is the data quantity successfully transmitted by each end station divided by the total time slot number allocated by the data quantity, and selecting 50 optimal individuals from the current population by using a roulette selection method; randomly selecting individuals to cross to generate new individuals, and performing mutation operation on the new individuals to increase diversity of the population; repeating the process until 100 iterations are reached or the fitness of the population is no longer improved; and selecting the individual with the highest fitness from the last generation population as the optimal time slot allocation scheme. Through this process, a slot allocation scheme is found that can meet the communication needs of the end station and maximize communication efficiency. The master station adjusts the reverse slot plan in the broadcast slots of the forward frame according to the optimal slot allocation scheme. This adjusted forward frame is sent to all end stations to ensure that each end station can communicate according to the latest slot schedule.
In this embodiment, the master station can dynamically adjust the timeslot allocation to adapt to the continuously changing communication requirements, and improve the communication efficiency of the entire satellite communication system; the genetic algorithm can find the approximate optimal solution in the complex search space, has good global search capability, and is suitable for solving the optimization problem of time slot allocation.
Further, in order to enhance the security of the communication link, encrypted communication and authentication are introduced, and the forward frame is encrypted, specifically:
s2a, adding data integrity check into a forward frame through a hash function;
s2b, encrypting the forward frame added with the data integrity check by adopting an encryption algorithm;
S2c, using an identity verification mechanism to confirm the identity of the end station, and sending the encrypted forward frame to the end station after confirming the identity.
In a further embodiment, the primary station collects the data to be transmitted and processes it, the processed data being divided into a plurality of data packets. For each data packet, the master station calculates its hash value using a hash function (e.g., SHA-256) and appends this hash value to the end of the data packet, which ensures the integrity of each data packet during transmission; the master station then encrypts the data packet containing the hash value using an encryption algorithm (e.g., AES), the master station generates a key, and encrypts the data using the key. The encrypted data packet is transmitted to the satellite; the master station uses an authentication mechanism (e.g., public key infrastructure PKI) to confirm the identity of the end station prior to transmitting the data. The end station must provide a valid certificate to pass the verification and once the identity of the end station is confirmed, the encrypted data packet is sent to the end station. After receiving the data packet, the end station first decrypts the data using the corresponding key. The end station then extracts the hash value from the decrypted packet and hashes the remainder of the packet again, and if the computed hash value matches the received hash value, the packet is considered complete.
By encrypting the data, the embodiment can prevent unauthorized access and interception, and even if the data is intercepted, the data content cannot be read without a corresponding key, so that the confidentiality of the data is ensured. By using the authentication mechanism, it is ensured that only authenticated end stations can receive and transmit data, thus preventing illegal devices from accessing the network and enhancing the security of communication.
Further, the reverse frame data is compressed, specifically:
S4a, acquiring reverse frame data, and classifying the reverse frame data according to the type of the reverse frame data, wherein the reverse frame data comprises control information and service data;
s4b, compressing the reverse frame data based on the classification result to form compressed data;
s4c, performing consistency check on the compressed data and the reverse frame data;
And S4d, filling the checked compressed data into a reverse frame structure to form a reverse frame.
In a further embodiment, the primary station obtains data from the reverse frame, which may include control information (e.g. instructions, configuration parameters) and traffic data (e.g. sensor readings, image data), which the primary station classifies as control information or traffic data according to the type of data; compressing the traffic data to reduce the amount of data, for example using a lossless compression algorithm (e.g. the Lempel-Ziv-Welch algorithm) or a lossy compression algorithm (e.g. JPEG); control information typically does not need to be compressed because it is typically small and requires high transmission speeds; the master station calculates a checksum (e.g., CRC or hash value) of the compressed data; after receiving the data, the receiving end executes the same checksum calculation and compares the checksum calculation with the value of the sending end so as to ensure the consistency of the data; filling the checked compressed data into a reverse frame structure.
In the present embodiment, by classifying the reverse frame data, the control information and the traffic data are distinguished, which helps to efficiently process different types of data; by compressing the data, the transmission quantity of the data is reduced, so that the bandwidth and resources of a satellite communication system are saved, the compressed data can be transmitted more quickly, the delay is reduced, and the energy consumption is reduced; by performing consistency check on the compressed data and the reverse frame data, no error or loss of the data occurs in the transmission process, which is helpful for improving the reliability of data transmission.
According to another aspect of the application, step S5 further comprises optimizing the control slots in the reverse frame, in particular:
S5a, acquiring historical network data and real-time network data, wherein the historical network data and the real-time network data comprise signal quality, transmission delay and bandwidth use conditions;
S5b, constructing a graph neural network model, training the graph neural network model by using historical network data, and verifying the trained graph neural network model by using real-time network data;
S5c, generating a strategy for optimizing the control time slot by using the verified graph neural network model;
s5d, applying a strategy for optimizing the control time slot to the network, and adjusting the allocation of the control time slot.
In this embodiment, the master station periodically collects data of signal quality, transmission delay and bandwidth usage from the end stations and stores it in a database. The historical network data and the real-time network data are arranged into a format suitable for training. For example, signal quality, transmission delay, and bandwidth usage are taken as input features. The satellite communication network is modeled as a graph structure in which nodes represent communication devices or satellites and edges represent communication links. Using a graph neural network (e.g., graph Convolutional Networks, GCNs) to learn the representation of the network, GCNs can capture relationships and local structures between nodes. The model is trained using historical network data, and the optimization objective may be to minimize transmission delay, maximize signal quality, or balance both. And verifying the model by using real-time network data to ensure that the model can accurately reflect the current state of the network. And predicting the real-time data by using the verified graph neural network model. For example, predicting the transmission delay and signal quality of the next slot, generating a strategy to adjust the control slot based on the prediction results and optimization objectives may involve reallocating broadcast slots, adjusting login slots, etc. The generated policies are applied to the network, and allocation of control slots is dynamically adjusted through Software Defined Network (SDN) technology.
According to the embodiment, a graph neural network model is introduced, historical network data is used for training, and verification is carried out according to real-time network data, so that resource allocation can be dynamically adjusted according to actual requirements, and satellite communication resources are effectively utilized. The verified graphic neural network model can generate an optimized control time slot strategy, so that time slot allocation can be automatically adjusted according to network states and requirements, and the performance is improved to the greatest extent.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details of the above embodiments, and various equivalent changes can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the equivalent changes belong to the protection scope of the present invention.
Claims (8)
1. A time division duplex communication method suitable for satellite communication, comprising the steps of:
S1, acquiring a coordination world time signal, and determining coordination world time of a preset timing time slot sending moment based on the coordination world time signal;
S2, respectively constructing a forward frame structure and a reverse frame structure by the master station, acquiring forward frame data based on coordinated universal time, and filling the forward frame data into the forward frame structure to form a forward frame; the forward frame structure comprises a forward service time slot, a timing time slot and a broadcasting time slot; the reverse frame structure comprises a reverse service time slot, a control time slot and a login time slot;
S3, the end station receives the forward frame and analyzes the forward frame;
S4, based on the analysis result, reverse frame data are obtained, and are filled into a reverse frame structure to form a reverse frame;
s5, the master station receives the reverse frame, adjusts the broadcast time slot in the forward frame based on the control time slot in the reverse frame, and obtains an adjusted forward frame;
step S1 is further as follows:
S11, acquiring a second pulse signal and a day time signal through a GPS time service instrument, and recovering a coordinated universal time signal from the second pulse signal and the day time signal;
S12, determining the sending moment of a timing time slot according to a preset time slot schedule;
S13, acquiring coordinated universal time of the timing time slot sending moment based on the coordinated universal time signal;
Step S2 is further as follows:
S21, respectively constructing a forward frame structure and a reverse frame structure by a master station, wherein the forward frame structure comprises a forward service time slot, a timing time slot and a broadcasting time slot; the reverse frame structure comprises a reverse service time slot, a control time slot and a login time slot;
s22, sending the coordinated universal time into a baseband generating module, generating timing time slot data through a modulation and coding mode, and filling the timing time slot data into the timing time slot;
s23, acquiring forward user data, generating forward service time slot data based on the forward user data, and filling the forward service time slot data into the forward service time slot;
S24, constructing a reverse time slot plan, generating broadcast time slot data based on the reverse time slot plan, and filling the broadcast time slot data into the broadcast time slot;
S25, forming a forward frame based on the timing time slot, the forward service time slot and the broadcast time slot after filling the data.
2. The time division duplex communication method according to claim 1, wherein step S3 further comprises:
S31, the end station receives the forward frame, analyzes the timing time slot in the forward frame and realizes time synchronization with the master station;
s32, analyzing a broadcast time slot in the forward frame, and determining a broadcast information detection window according to the timing time slot and the broadcast time slot;
s33, based on the broadcast information detection window and the broadcast time slot, acquiring a reverse time slot planning period and the login time of the terminal station for system network access;
s34, analyzing the forward service time slot in the forward frame, and carrying out parameter statistics on the user data in the forward service time slot.
3. The time division duplex communication method according to claim 2, wherein step S4 further comprises:
S41, generating login time slot data based on the login time of the system network access of the end station obtained through analysis, and filling the login time slot data into the login time slot;
S42, generating control time slot data based on the analysis result of the parameter statistics, and filling the control time slot data into the control time slot;
s43, acquiring reverse user data, generating reverse service time slot data based on the reverse user data, and filling the reverse service time slot data into a reverse service time slot;
s44, forming a reverse frame based on the login time slot, the control time slot and the reverse service time slot after filling data;
s45, transmitting the reverse frame to the master station according to the reverse time slot planning period.
4. A time division duplex communication method according to claim 3, wherein step S5 is further:
s51, the master station receives a reverse frame and monitors a control time slot in the reverse frame;
S52, judging whether the end station is online or not based on the monitoring result, and skipping the end station which is not online if the end station is not online; if online, go to step S53;
S53, analyzing a control time slot in a reverse Frame to obtain a parameter statistical result, adjusting a reverse time slot plan in a broadcast time slot of a forward Frame based on the parameter statistical result to ensure that forward reverse non-service time slots are not overlapped in time, and meeting that the forward Frame length and the reverse Frame length have the least common multiple, namely meeting M x Frame forward=N*Framebackward, wherein Frame forward represents the total duration occupied by a single forward Frame, frame backward represents the total duration occupied by a single reverse Frame, M, N respectively represents the number of forward frames and reverse frames, and obtaining an adjusted forward Frame;
and S54, the adjusted forward frame is sent to the end station.
5. The time division duplex communication method according to claim 4, wherein step S53 further comprises:
s531, analyzing a control time slot in a reverse frame to obtain a parameter statistical result, wherein the parameter statistical result comprises the communication requirement and the priority of each terminal station;
S532, based on the result of parameter statistics, evaluating the current time slot allocation situation, and if the current allocation meets the requirement, keeping unchanged; if not, proceeding to step S533;
S533, calculating to obtain an optimal time slot allocation scheme by adopting an optimization algorithm based on the evaluation result; the optimization goal of the optimal time slot allocation scheme is to maximize the communication efficiency of the whole system, ensure that the forward and reverse non-service time slots are not overlapped in time, and meet the condition that the forward frame length and the reverse frame length have the least common multiple;
and S534, adjusting a reverse time slot plan in the broadcast time slot of the forward frame based on the optimal time slot allocation scheme to obtain an adjusted forward frame.
6. The time division duplex communication method according to claim 4, wherein step S2 further comprises encrypting the forward frame, specifically:
s2a, adding data integrity check into a forward frame through a hash function;
s2b, encrypting the forward frame added with the data integrity check by adopting an encryption algorithm;
S2c, using an identity verification mechanism to confirm the identity of the end station, and sending the encrypted forward frame to the end station after confirming the identity.
7. The method for time division duplex communications according to claim 4, wherein step S4 further comprises compressing the reverse frame data, specifically:
S4a, acquiring reverse frame data, and classifying the reverse frame data according to the type of the reverse frame data, wherein the reverse frame data comprises control information and service data;
s4b, compressing the reverse frame data based on the classification result to form compressed data;
s4c, performing consistency check on the compressed data and the reverse frame data;
And S4d, filling the checked compressed data into a reverse frame structure to form a reverse frame.
8. The method for tdd communication according to claim 4, wherein step S5 further comprises optimizing a control slot in a reverse frame, specifically:
S5a, acquiring historical network data and real-time network data, wherein the historical network data and the real-time network data comprise signal quality, transmission delay and bandwidth use conditions;
S5b, constructing a graph neural network model, training the graph neural network model by using historical network data, and verifying the trained graph neural network model by using real-time network data;
S5c, generating a strategy for optimizing the control time slot by using the verified graph neural network model;
s5d, applying a strategy for optimizing the control time slot to the network, and adjusting the allocation of the control time slot.
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