Satellite short message data transmission method and device

Abstract

The present application relates to the technical field of satellite communication, and especially relates to a satellite short message data transmission method and device. The method comprises the following steps: an end receiving device establishes an initial communication link with a satellite through a preset guide sequence, and carries out time synchronization and frequency synchronization, and generates a security parameter negotiation channel; an encryption capability message is sent to the satellite through the security parameter negotiation channel, and an end-to-end corresponding encryption communication channel is established; a short message data transmission request is sent to the satellite through the encryption communication channel, and beam configuration parameters are sent to the end receiving device through the encryption communication channel; the end receiving device adjusts a corresponding receiving antenna according to the beam configuration parameters to form a directional receiving beam, and when a preset threshold is reached, a resource reallocation mechanism is triggered to dynamically adjust beam resources occupied by low-priority services to high-priority services. The present application can realize efficient and reliable transmission of satellite short message data.

Description

Technical Field

[0001] This invention relates to the field of satellite communication technology, and in particular to a satellite short message data transmission method and apparatus. Background Technology

[0002] With the continuous development of satellite communication technology, satellite short message data transmission, as an efficient communication method, is widely used in aerospace, military, disaster relief, meteorological monitoring, and other fields. In some special environments, such as at sea, in deserts, or in polar regions far from ground base stations, traditional communication methods often cannot provide stable and timely services. Satellite short message data transmission systems, due to their lack of geographical limitations and wide coverage, have become a key technology in these fields. However, most existing satellite short message data transmission methods rely on large-capacity data transmission channels, generally employing static frequencies and fixed transmission protocols. They lack flexibility and adaptability, making it difficult to automatically optimize transmission performance based on resource changes. This results in poor adaptability to complex scenarios such as multi-task communication and multi-channel transmission, thus failing to achieve efficient and stable communication. Summary of the Invention

[0003] Therefore, it is necessary for the present invention to provide a satellite short message data transmission method and apparatus to solve at least one of the above-mentioned technical problems.

[0004] To achieve the above objectives, a satellite short message data transmission method includes the following steps:

[0005] The receiving device establishes an initial communication link with the satellite through a preset guidance sequence, and performs time and frequency synchronization on the initial communication link between the receiving device and the satellite based on the guidance sequence to generate a security parameter negotiation channel; the receiving device sends an encryption capability message to the satellite through the security parameter negotiation channel, and negotiates and generates a session key with the satellite based on the encryption capability message, and establishes an end-to-end corresponding encrypted communication channel according to the session key;

[0006] The receiving device sends a short message data transmission request to the satellite through the encrypted communication channel. The short message data transmission request includes service type, quality of service level, and data priority information.

[0007] Based on the short message data transmission request, the satellite allocates corresponding beam resources according to a preset resource scheduling strategy and sends beam configuration parameters to the receiving device through the encrypted communication channel.

[0008] The receiving device adjusts the corresponding receiving antenna according to the beam configuration parameters to form a directional receiving beam, and receives the short message data sent by the satellite through the directional receiving beam;

[0009] The satellite monitors the resource usage status of each directional receiving beam in real time. When the utilization rate of the beam resources in the resource usage status reaches a preset threshold, a resource reallocation mechanism is triggered to dynamically adjust the beam resources occupied by low-priority services to be used by high-priority services.

[0010] Furthermore, the guiding sequence adopts an orthogonal sequence set with zero correlation region characteristics. The orthogonal sequence set includes multiple mutually orthogonal sub-sequences, each of which corresponds to a different satellite service area, for the purpose of enabling rapid association between the receiving device and the target satellite.

[0011] Furthermore, the step of synchronizing the time and frequency of the initial communication link between the receiving device and the satellite based on the guiding sequence includes the following steps:

[0012] The receiving device extracts the time synchronization symbol of each subsequence in the guide sequence, and calculates the deviation value between the local clock and the satellite clock based on the time synchronization symbol through a preset sliding window size;

[0013] The local clock of the receiving device is adjusted based on the deviation value so that the time synchronization accuracy between the receiving device and the satellite reaches a preset synchronization level, and a time synchronization result is obtained.

[0014] The receiving device extracts the frequency synchronization symbol of each subsequence in the pilot sequence and estimates the frequency offset corresponding to the frequency synchronization symbol through a spectrum analysis algorithm.

[0015] The local oscillator frequency of the receiving device is adjusted based on the frequency offset to ensure that the carrier frequency synchronization accuracy between the receiving device and the satellite reaches a preset synchronization level, and a frequency synchronization result is obtained.

[0016] The receiving device generates a synchronization confirmation message based on the time synchronization result and the frequency synchronization result. The synchronization confirmation message includes a timestamp, a frequency correction value, and a synchronization quality index. Based on the synchronization confirmation message, the receiving device performs time and frequency synchronization confirmation on the initial communication link between the receiving device and the satellite, and generates a security parameter negotiation channel.

[0017] Furthermore, the receiving device sends an encryption capability message to the satellite through the security parameter negotiation channel, and negotiates with the satellite to generate a session key based on the encryption capability message. Establishing an end-to-end encrypted communication channel based on the session key includes the following steps:

[0018] The receiving device generates an encryption capability message containing a list of encryption algorithms it supports, the key exchange protocol type, and the length of the security parameters.

[0019] The encryption capability message is sent to the satellite through the security parameter negotiation channel, and the encryption selection message returned by the satellite is received. The encryption selection message contains the specific encryption algorithm, key exchange protocol and security parameters selected by the satellite from the encryption capability messages supported by the receiving device.

[0020] The receiving device and the satellite negotiate and generate shared key material based on the encrypted selection message using the Diffie-Hellman key exchange algorithm.

[0021] The receiving device and the satellite respectively perform hash processing on the shared key material to generate the same session key, and verify the consistency of the session key through a key confirmation mechanism;

[0022] The receiving device and the satellite establish an end-to-end encrypted communication channel based on the session key. The encrypted communication channel uses a symmetric encryption algorithm to encrypt and protect the transmitted data.

[0023] Furthermore, after the receiving device sends a short message data transmission request to the satellite through the encrypted communication channel, the process further includes the following steps:

[0024] The receiving device encapsulates the short message data to be transmitted in a format to generate an original request message containing a service type identifier, service quality level parameters, and data priority markers.

[0025] The original request message is digitally signed to generate a signed request message containing a message digest and a signature value. The data signature is implemented using elliptic curve digital signature.

[0026] The signature request message is encrypted using the session key to generate an encrypted request data packet;

[0027] The encrypted request data packet is sent to the satellite through the encrypted communication channel, and a request confirmation message is received from the satellite. The request confirmation message contains the request processing status and resource allocation pre-indication information.

[0028] Furthermore, the satellite, based on the short message data transmission request, allocates corresponding beam resources according to a preset resource scheduling strategy, and sends beam configuration parameters to the receiving device through the encrypted communication channel, including the following steps:

[0029] The satellite parses the short message data transmission request to extract information such as service type, quality of service level, and data priority.

[0030] According to the preset resource scheduling strategy, the corresponding beam resources are selected and allocated from the available beam resource pool within the satellite based on the service type, service quality level, and data priority information.

[0031] The beam resources are configured with parameters to generate beam configuration parameters that include beam center frequency, bandwidth, modulation scheme, coding rate and power control parameters.

[0032] The beam configuration parameters are encrypted using the session key to generate an encrypted beam configuration data packet;

[0033] The encrypted beam configuration data packet is sent to the receiving device through the encrypted communication channel, and a configuration confirmation message is received from the receiving device. The configuration confirmation message includes the reception status and adjustment suggestions corresponding to the beam configuration parameters.

[0034] Furthermore, the receiving device adjusts the corresponding receiving antenna according to the beam configuration parameters to form a directional receiving beam, and receives the short message data sent by the satellite through the directional receiving beam, including the following steps:

[0035] The receiving device parses the beam configuration parameters to extract the beam center frequency, bandwidth, modulation method, coding rate, and power control parameters.

[0036] The physical parameters of the receiving antenna of the receiving device are adjusted according to the beam configuration parameters, including the phase distribution of the antenna array, the amplitude weighting coefficient and the polarization direction, so as to form a directional receiving beam pointing to the satellite.

[0037] The directional receiving beam receives the received signal corresponding to the short message sent by the satellite, and performs low-noise amplification, mixing and digitization processing on the received signal to generate a digitized received signal.

[0038] The digitized received signal is demodulated and decoded according to the modulation method and coding rate in the beam configuration parameters to obtain encrypted short message data;

[0039] The encrypted short message data is decrypted using the session key to obtain the short message data sent by the satellite, and the integrity of the short message data is verified through an integrity check mechanism.

[0040] Furthermore, the adjustment process of the phase distribution is specifically as follows:

[0041] The beam center frequency in the beam configuration parameters is analyzed to determine the operating frequency of the antenna array, and the wavelength of the electromagnetic wave corresponding to the receiving antenna in free space is calculated based on the operating frequency.

[0042] Based on the bandwidth in the beam configuration parameters, the wavelength of the electromagnetic wave in free space is analyzed spatially to obtain wavelength spatial angle information, including azimuth and elevation angles.

[0043] The direction vector of the antenna array in the corresponding coordinate system is determined based on the wavelength spatial angle information, and the dot product between the direction vector and the position coordinates of each element in the antenna array in the coordinate system is calculated to obtain the dot product between the direction vector and the position of each element.

[0044] Based on the wavelength and the dot product between the direction vector and the position of each element, the phase offset of each element is calculated, and the phase distribution of the antenna array is adjusted according to the phase offset.

[0045] Furthermore, the satellite monitors the resource usage status of each directional receiving beam in real time. When the utilization rate of the beam resources in the resource usage status reaches a preset threshold, a resource reallocation mechanism is triggered to dynamically adjust the beam resources occupied by low-priority services to be used by high-priority services. This includes the following steps:

[0046] The satellite continuously collects the resource usage status corresponding to each directional receiving beam, including beam occupancy time, beam transmission rate, bit error rate, and signal strength;

[0047] Based on the resource usage status, the beam resource utilization rate corresponding to each directional receiving beam is calculated and compared with a preset utilization rate threshold. When the beam resource utilization rate is detected to reach or exceed the preset utilization rate threshold, the resource reallocation mechanism is triggered and a resource reallocation trigger signal is generated.

[0048] Based on the resource reallocation trigger signal, priority assessment is performed on all services currently occupying the beam resources to determine the list of low-priority services and the list of high-priority services.

[0049] According to the resource reallocation mechanism, the maximum allowable service degradation range for each low-priority service in the low-priority service list is determined based on the corresponding service type and service quality level. The beam resources occupied by the low-priority services are gradually released in descending order of the maximum service degradation range, and the released beam resources are reallocated to the corresponding high-priority services in the high-priority service list. At the same time, the service quality status of the downgraded low-priority services is continuously monitored. When sufficient beam resources are detected, the service recovery process is triggered to gradually restore the downgraded low-priority services according to the preset recovery strategy.

[0050] Furthermore, the present invention also provides a satellite short message data transmission apparatus for performing the satellite short message data transmission method described above, the satellite short message data transmission apparatus comprising:

[0051] The satellite communication establishment module is used for the receiving device to establish an initial communication link with the satellite through a preset guidance sequence, and to perform time and frequency synchronization of the initial communication link between the receiving device and the satellite based on the guidance sequence, thereby generating a security parameter negotiation channel; the receiving device sends an encryption capability message to the satellite through the security parameter negotiation channel, and negotiates and generates a session key with the satellite based on the encryption capability message, and establishes an end-to-end corresponding encrypted communication channel according to the session key;

[0052] The transmission request sending module is used for the receiving device to send a short message data transmission request to the satellite through the encrypted communication channel. The short message data transmission request includes service type, service quality level and data priority information.

[0053] The transmission beam configuration module is used by the satellite to allocate corresponding beam resources according to a preset resource scheduling strategy based on the short message data transmission request, and to send beam configuration parameters to the receiving device through the encrypted communication channel.

[0054] The directional short message receiving module is used by the receiving device to adjust the corresponding receiving antenna according to the beam configuration parameters to form a directional receiving beam, and to receive the short message data sent by the satellite through the directional receiving beam;

[0055] The beam resource reconfiguration module is used for satellite real-time monitoring of the resource usage status corresponding to each directional receiving beam. When the utilization rate of the beam resource in the resource usage status reaches a preset threshold, the resource reconfiguration mechanism is triggered to dynamically adjust the beam resources occupied by low-priority services to be used by high-priority services.

[0056] The beneficial effects of this invention are:

[0057] 1. Compared with existing technologies, the satellite short message data transmission method proposed in this invention has the following advantages: It establishes an initial communication link between the receiving device and the satellite through a guiding sequence, and performs time and frequency synchronization. The key to this process is ensuring the stability and security of data transmission. By establishing an initial communication link with the satellite, the receiving device can ensure the quality of subsequent communication and avoid data loss or errors caused by synchronization problems. Time synchronization ensures that both communicating parties have a shared understanding of the time, while frequency synchronization avoids the effects of signal offset or drift, ensuring accurate data transmission. Through this process, a secure parameter negotiation channel is generated between the receiving device and the satellite. This channel is the basis for data encryption and security negotiation. Through this channel, the receiving device can send encryption capability messages to the satellite, thereby initiating encrypted communication negotiation between the two parties. Based on the negotiated session key, both parties can achieve end-to-end encryption protection in subsequent communications. This effectively improves the security and privacy protection capabilities of communication, providing a guarantee for subsequent short message transmission. Secondly, the receiving device sends a short message data transmission request to the satellite through the previously established encrypted communication channel. This request includes not only the data content to be transmitted, but also the service type, quality of service (QoS) level, and data priority information. This information is crucial for satellite resource scheduling, enabling the satellite to rationally allocate communication resources according to the needs of different services, ensuring that high-priority tasks are processed first. The key to this step is to ensure that different types of data receive appropriate bandwidth and latency guarantees based on their service requirements by refining the data transmission request. This on-demand resource allocation method improves overall communication efficiency and reduces the impact of low-priority services on high-priority services. Then, based on the received short message data transmission request and a preset resource scheduling strategy, the satellite allocates beam resources. The satellite's resource scheduling strategy is usually based on multiple factors, such as data priority, QoS requirements, and network load, aiming to maximize the use of limited spectrum resources. In this step, the satellite not only adjusts resource allocation according to the receiving device's request but also considers the priority of different communication tasks to ensure that high-priority tasks receive the necessary resource support. This flexible resource scheduling mechanism helps improve the overall communication system's response speed and stability, ensuring that different types of data can be transmitted efficiently under the specified QoS level. Furthermore, the receiving equipment adjusts its receiving antenna according to the beam configuration parameters sent by the satellite to form a directional receiving beam. This operation is achieved through precise antenna control, which can improve the quality and strength of the received signal. By using a directional receiving beam, the receiving equipment can maximize the reception of the signal sent by the satellite, thereby reducing signal attenuation and interference. This directional receiving method not only improves the efficiency of data transmission, but also effectively reduces signal interference. In particular, it can better improve its adaptability in complex scenarios such as multi-task communication and multi-channel transmission.Furthermore, precise control of the receiving beams can further optimize spectrum utilization, improve resource efficiency, and thus enhance the performance of the entire communication system. Finally, the satellite monitors the resource usage status of each directional receiving beam in real time. When the utilization rate of certain beam resources reaches a preset threshold, a resource reallocation mechanism is activated. This mechanism dynamically adjusts the allocation of beam resources based on the priority of each service. Low-priority services are given priority in resource allocation when resources are scarce, and the released beam resources are reallocated to high-priority services. This mechanism ensures that the priority of important tasks is guaranteed even with limited communication network resources. Its advantage lies in automatically optimizing transmission performance through flexible resource management, achieving optimal beam resource allocation, and reducing the impact of low-priority tasks on high-priority tasks, thereby further realizing efficient and stable satellite short message communication.

[0058] 2. The satellite short message data transmission device proposed in this invention is composed of a satellite communication establishment module, a transmission request sending module, a transmission beam configuration module, a directional short message receiving module, and a beam resource reconfiguration module. It can realize any satellite short message data transmission method described in this invention. It is used to combine the operations between the computer programs running on each module to realize the satellite short message data transmission method. The internal structure of the system cooperates with each other, which can greatly reduce repetitive work and manpower input, and can quickly and effectively provide a more accurate and efficient satellite short message data transmission process, thereby simplifying the operation process of the satellite short message data transmission device. Attached Figure Description

[0059] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0060] Figure 1 This is a flowchart illustrating the steps of the satellite short message data transmission method of the present invention;

[0061] Figure 2 This is a detailed flowchart illustrating the steps involved in synchronizing the time and frequency of the initial communication link between the receiving device and the satellite based on the guiding sequence. Detailed Implementation

[0062] The technical method of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0063] Furthermore, the accompanying drawings are merely illustrative of the invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor methods and / or microcontroller methods.

[0064] It should be understood that although the terms "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are used merely to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0065] To achieve the above objectives, please refer to Figures 1 to 2 This invention provides a satellite short message data transmission method, the method comprising the following steps:

[0066] The receiving device establishes an initial communication link with the satellite through a preset guidance sequence, and performs time and frequency synchronization on the initial communication link between the receiving device and the satellite based on the guidance sequence to generate a security parameter negotiation channel; the receiving device sends an encryption capability message to the satellite through the security parameter negotiation channel, and negotiates and generates a session key with the satellite based on the encryption capability message, and establishes an end-to-end corresponding encrypted communication channel according to the session key;

[0067] The receiving device sends a short message data transmission request to the satellite through the encrypted communication channel. The short message data transmission request includes service type, quality of service level, and data priority information.

[0068] Based on the short message data transmission request, the satellite allocates corresponding beam resources according to a preset resource scheduling strategy and sends beam configuration parameters to the receiving device through the encrypted communication channel.

[0069] The receiving device adjusts the corresponding receiving antenna according to the beam configuration parameters to form a directional receiving beam, and receives the short message data sent by the satellite through the directional receiving beam;

[0070] The satellite monitors the resource usage status of each directional receiving beam in real time. When the utilization rate of the beam resources in the resource usage status reaches a preset threshold, a resource reallocation mechanism is triggered to dynamically adjust the beam resources occupied by low-priority services to be used by high-priority services.

[0071] In the embodiments of this invention, please refer to Figure 1 The diagram shown is a flowchart illustrating the steps of the satellite short message data transmission method of the present invention. In this example, the satellite short message data transmission method includes the following steps:

[0072] S1: The receiving device establishes an initial communication link with the satellite through a preset guidance sequence, and performs time and frequency synchronization on the initial communication link between the receiving device and the satellite based on the guidance sequence to generate a security parameter negotiation channel; the receiving device sends an encryption capability message to the satellite through the security parameter negotiation channel, and negotiates and generates a session key with the satellite based on the encryption capability message, and establishes an end-to-end corresponding encrypted communication channel according to the session key;

[0073] In this embodiment of the invention, the receiving device establishes an initial communication link with the satellite through a preset guidance sequence. After powering on, the receiver's RF front-end automatically scans 16 frequency points within the L-band range of 1610-1626.5MHz, with each frequency point spaced 1MHz apart. When the guidance sequence sent by the satellite is received, the receiver's synchronization circuit uses a correlation detection algorithm based on a matched filter to calculate the correlation between the received signal and a locally stored 1023-bit Gold sequence. Synchronization is considered successful when the correlation peak exceeds a threshold of 0.8. Time synchronization is achieved by measuring the difference between the received time of the guidance sequence and the local high-precision atomic clock time, achieving an accuracy of ±1μs. Frequency synchronization employs phase-locked loop (PLL) technology; the receiver's frequency synthesizer adjusts the local oscillation frequency according to the received guidance sequence frequency, achieving an accuracy of ±0.1ppm. After synchronization is complete, a security parameter negotiation channel is generated. This channel uses a dedicated physical... The system employs a layered frame structure. The frame header contains a specific synchronization code and a channel identifier. The receiving device sends an encryption capability message to the satellite through a security parameter negotiation channel. This message includes the three symmetric encryption algorithms supported by the receiving device: AES-128, AES-192, and AES-256; a key length range of 128-256 bits; and public key authentication based on digital certificates and authentication based on pre-shared keys. The satellite selects the AES-256 algorithm based on the receiving device's encryption capabilities and generates a session key through the Diffie-Hellman key exchange protocol. Both parties generate temporary private and public keys and exchange public key information through the security parameter negotiation channel. Based on their respective private keys and the other party's public key, they calculate a shared key, which is then hashed using SHA-256 to generate a 256-bit session key. An encrypted communication channel using CCM mode is established based on the session key to ensure the confidentiality and integrity of data transmission. The establishment process is completed within 3 seconds.

[0074] S2: The receiving device sends a short message data transmission request to the satellite through the encrypted communication channel. The short message data transmission request includes service type, quality of service level, and data priority information.

[0075] In this embodiment of the invention, the receiving device sends a short message data transmission request to the satellite through an encrypted communication channel. The request adopts a dedicated message format, and the service types are divided into four categories: voice communication, image transmission, text short message, and control command. These are represented by a 1-byte service type field, with voice communication encoded as 0x01, image transmission encoded as 0x02, text short message encoded as 0x03, and control command encoded as 0x04. The service quality level is divided into 5 levels, represented by a 1-byte service quality level field, with level 1 being the highest priority (encoded as 0x01) and level 5 being the lowest priority (encoded as 0x05). The data priority information is represented by a 3-byte composite field, including three dimensions: urgency, importance, and timeliness. The urgency level is divided into 4 levels, represented by 2 binary digits: 00 for moderate urgency, 01 for urgency, 10 for very urgent urgency, and 11 for extremely urgent urgency. The importance level is divided into 3 levels, represented by 2 binary digits: 00 for moderate importance, 01 for importance, and 10 for very important importance. The timeliness level is divided into 5 levels, represented by 3 binary digits: 000 for low timeliness requirement, 001 for relatively low timeliness requirement, 010 for medium timeliness requirement, 011 for relatively high timeliness requirement, and 100 for high timeliness requirement. The message body of the short message data transmission request is encoded in TLV format and also includes information such as the receiving device ID, request sequence number, and timestamp. The receiving device ID uses a 16-byte globally unique identifier, generated based on the EUI-64 standard of the IEEE 802 standard. The request sequence number uses a 4-byte incrementing counter, incrementing by 1 with each new request. The timestamp uses a 6-byte UNIX time format, representing the number of milliseconds from January 1, 1970, 00:00:00 UTC to the current time. When the request is sent through the encrypted communication channel, the message body is first encrypted with AES-256 using the session key, a 16-byte HMAC-SHA256 message authentication code is added, and it is encapsulated in a fixed-length 128-byte MAC frame. The frame header contains information such as frame type, frame length, source address, and destination address. The request is assembled and sent within 100ms.

[0076] S3: Based on the short message data transmission request, the satellite allocates corresponding beam resources according to the preset resource scheduling strategy, and sends beam configuration parameters to the receiving device through the encrypted communication channel;

[0077] In this embodiment of the invention, based on the short message data transmission request sent by the satellite to the receiving device, corresponding beam resources are allocated according to a preset resource scheduling strategy. The satellite's resource scheduling unit parses the service type, service quality level, and data priority information in the request, and constructs a resource requirement vector containing parameters such as bandwidth requirements, latency requirements, and bit error rate requirements. The bandwidth requirement is determined according to the service type and service quality level; for voice communication services, it is 16kbps; for image transmission services, it is divided into 128kbps (640×480) and 512kbps (1024×768) depending on the resolution; and for text short messages, it is 16kbps. The message processing speed is 4kbps, and the control command speed is 2kbps. Latency requirements are determined based on the urgency and timeliness of the data priority. Extremely urgent and time-sensitive data requires a latency of ≤100ms; very urgent and time-sensitive data requires a latency of ≤200ms; urgent and medium-urgent data requires a latency of ≤500ms; generally urgent and low-urgent data requires a latency of ≤1000ms; and generally urgent and low-urgent data requires a latency of ≤5000ms. Bit error rate requirements are determined based on the service quality level; Level 1 service quality requires a bit error rate of ≤10%. -6 Level 2 service quality requires a bit error rate of ≤10%. -5 Level 3 service quality requires a bit error rate of ≤10%. -4 Level 4 service quality requires a bit error rate of ≤10%. -3 Level 5 service quality requires a bit error rate of ≤10%. -2The preset resource scheduling strategy employs a multi-objective optimization algorithm to screen candidate beams that meet basic requirements. It calculates the resource allocation cost function for each candidate beam, which includes resource utilization, interference, and fairness terms. The optimal beam resource allocation scheme is determined by minimizing the cost function. Parameters such as beam ID, center frequency, bandwidth, modulation scheme, and coding rate are specified for the receiving equipment. The modulation scheme is selected based on the service type and quality of service level: BPSK modulation is used for control command services, QPSK modulation for short text messages, 8PSK modulation for voice communication services, and 16QAM modulation for image transmission services. The coding rate is selected based on channel conditions and bit error rate requirements; services with high bit error rate requirements use lower coding rates. For services with low error rate requirements, a higher coding rate (e.g., 3 / 4) is used. The satellite sends beam configuration parameters to the receiving equipment through an encrypted communication channel. These parameters use a dedicated configuration message format and include information such as beam ID (2 bytes), center frequency (4 bytes, unit Hz), bandwidth (2 bytes, unit kHz), modulation method (1 byte, BPSK encoding is 0x01, QPSK encoding is 0x02, 8PSK encoding is 0x03, 16QAM encoding is 0x04), and coding rate (1 byte, 1 / 2 encoding is 0x01, 2 / 3 encoding is 0x02, 3 / 4 encoding is 0x03, 5 / 6 encoding is 0x04). The message is assembled and sent within 50ms.

[0078] S4: The receiving device adjusts the corresponding receiving antenna according to the beam configuration parameters to form a directional receiving beam, and receives the short message data sent by the satellite through the directional receiving beam;

[0079] In this embodiment of the invention, the receiving device adjusts the corresponding receiving antenna according to the beam configuration parameters transmitted by the satellite to form a directional receiving beam. The antenna control unit of the receiving device analyzes the center frequency parameters and controls the frequency synthesizer to adjust the frequency of the local oscillator to the specified center frequency with an accuracy of ±0.05ppm. Then, the corresponding antenna pointing parameters are determined according to the beam ID. The mapping relationship between the beam ID and the antenna pointing angle is pre-stored in the read-only memory of the receiving device. Each beam ID corresponds to a unique azimuth and elevation angle. The antenna of the receiving device adopts phased array technology and consists of 64 antenna elements. Each antenna element is equipped with an independent phase shifter and amplifier. The antenna control unit calculates the phase weight of each antenna element according to the calculated azimuth and elevation angles using a digital beamforming algorithm based on the linear constraint minimum variance criterion. The fast Fourier transform algorithm is used to complete the phase weight calculation of the 64 antenna elements within 10ms. The antenna control unit sends the phase weights to the phase shifter of each antenna element through a dedicated control bus. The phase shifter adjusts the phase of the radio frequency signal to achieve directional control of the beam, and at the same time adjusts the amplifier gain to ensure balanced output power of each antenna element. After beamforming, the receiver's RF front-end performs low-noise amplification, down-conversion, and analog-to-digital conversion on the received signal to obtain a digital baseband signal. The digital baseband signal is first adjusted by an automatic gain control circuit, then processed by matched filtering, bit synchronization, and frame synchronization to recover the original transmission frame. The receiver demodulates and decodes the received signal according to the modulation scheme and coding rate in the beam configuration parameters. BPSK modulated signals are coherently demodulated, while QPSK, 8PSK, and 16QAM modulated signals are maximum likelihood demodulated. Decoding uses either the Viterbi algorithm or the Turbo code decoding algorithm, selecting appropriate decoding parameters based on the coding rate. The decoded short message data undergoes CRC-32 verification and parsing by the data processing unit to extract the payload, which is then stored in the receiver's data buffer. The entire beamforming and data reception process is completed within 20ms.

[0080] S5: The satellite monitors the resource usage status of each directional receiving beam in real time. When the utilization rate of the beam resources in the resource usage status reaches a preset threshold, a resource reallocation mechanism is triggered to dynamically adjust the beam resources occupied by low-priority services to high-priority services.

[0081] In this embodiment of the invention, the resource usage status of each directional receiving beam is monitored in real time by a satellite. When the utilization rate of the detected beam resource usage status reaches a preset threshold, a resource reallocation mechanism is triggered. The satellite's resource monitoring unit continuously collects the beam occupancy time, beam transmission rate, bit error rate, and signal strength of each directional receiving beam through a dedicated monitoring circuit. The beam occupancy time is monitored by a high-precision timer, which starts when the beam begins transmitting data and stops when transmission ends, accurately recording the duration of each transmission and accumulating the total occupancy time. The beam transmission rate is based on physical layer data frame parsing, using a sliding window algorithm with a sampling period of 100ms to calculate the average transmission rate within each period. The bit error rate is implemented through a cyclic redundancy check mechanism, calculating the bit error rate every 1000 data packets.Signal strength is measured by the power detection circuit of the RF front-end, converting the received RF signal into a voltage value, which is then converted into a digital signal strength value by an analog-to-digital converter, with the unit being dBm. The resource monitoring unit performs a comprehensive analysis of the collected parameters every 500ms, calculating the resource utilization rate of each directional receiving beam. The resource utilization rate uses a weighted comprehensive evaluation model, where beam occupancy time has a weight of 0.4, beam transmission rate has a weight of 0.3, bit error rate has a weight of 0.2, and signal strength has a weight of 0.1. The specific calculation formula is: Resource Utilization Rate = 0.4 × (Actual Occupancy Time) × (Beam Transmission Rate × (Actual Occupancy Time ... The calculation is: (Time / Maximum Available Time) + 0.3 × (Actual Transmission Rate / Maximum Theoretical Rate) + 0.2 × (1 - Bit Error Rate) + 0.1 × (Actual Signal Strength / Maximum Signal Strength). The preset utilization threshold is set to 0.85. When the calculated beam resource utilization reaches or exceeds 0.85, the resource monitoring unit immediately triggers the resource reallocation mechanism. The trigger signal includes information such as beam ID, current resource utilization, and resource usage status parameters, and is transmitted to the resource management unit via a dedicated control bus. After receiving the trigger signal, the resource management unit retrieves the current beam utilization from the service scheduling database. All service information is processed, and a multi-factor decision-making model is used to prioritize all services. Services are categorized into high-priority (score ≥ 3.5) and low-priority (score < 3.5) lists based on their priority scores. The resource management unit establishes a degradation strategy table for each service type and service quality level combination, determines the maximum service degradation range for each low-priority service, and sorts the low-priority services in descending order of maximum service degradation range. A degradation instruction is sent to the first low-priority service in the sorted list, which adjusts its service processing parameters and releases corresponding beam resources. The released beam resources are then redistributed to the highest-priority service in the high-priority service list whose resource requirements are not yet met. During resource redistribution, the resource monitoring unit continuously monitors the service quality status of the downgraded low-priority services. When beam resource utilization is detected to drop below 0.7, a service recovery process is triggered. Following a preset recovery strategy, downgraded low-priority services are gradually restored in ascending order of maximum service degradation range, restoring only a portion of the service quality of one service at a time. A 500ms monitoring period is then taken to check system resource usage, ensuring that restoring too many services at once does not cause resource strain again.

[0082] Furthermore, the guiding sequence adopts an orthogonal sequence set with zero correlation region characteristics. The orthogonal sequence set includes multiple mutually orthogonal sub-sequences, each of which corresponds to a different satellite service area, for the purpose of enabling rapid association between the receiving device and the target satellite.

[0083] In this embodiment of the invention, during satellite short message data transmission, the guiding sequence employs an orthogonal sequence set with zero correlation zone characteristics. Taking the BeiDou satellite system as an example, this orthogonal sequence set consists of 32 mutually orthogonal sub-sequences, each with a length of 128 code elements, using binary phase shift keying (BPSK) modulation. These 32 sub-sequences correspond to 32 different satellite service areas, such as specific sub-sequences assigned to North China, East China, and South China in my country. In practical applications, when the receiving device is located in the East China service area, the sub-sequence corresponding to the East China region in the guiding sequence sent by the target satellite will carry specific identification information. After receiving the satellite signal through the antenna, the receiving device processes the signal using a matched filter. Based on the orthogonality of each sub-sequence, it can accurately separate the sub-sequence corresponding to its own service area. Due to the zero correlation zone characteristic, there is no interference between different sub-sequences in complex environments such as multipath propagation, thereby achieving rapid association between the receiving device and the target satellite, laying the foundation for subsequent synchronization operations.

[0084] Furthermore, the step of synchronizing the time and frequency of the initial communication link between the receiving device and the satellite based on the guiding sequence includes the following steps:

[0085] The receiving device extracts the time synchronization symbol of each subsequence in the guide sequence, and calculates the deviation value between the local clock and the satellite clock based on the time synchronization symbol through a preset sliding window size;

[0086] The local clock of the receiving device is adjusted based on the deviation value so that the time synchronization accuracy between the receiving device and the satellite reaches a preset synchronization level, and a time synchronization result is obtained.

[0087] The receiving device extracts the frequency synchronization symbol of each subsequence in the pilot sequence and estimates the frequency offset corresponding to the frequency synchronization symbol through a spectrum analysis algorithm.

[0088] The local oscillator frequency of the receiving device is adjusted based on the frequency offset to ensure that the carrier frequency synchronization accuracy between the receiving device and the satellite reaches a preset synchronization level, and a frequency synchronization result is obtained.

[0089] The receiving device generates a synchronization confirmation message based on the time synchronization result and the frequency synchronization result. The synchronization confirmation message includes a timestamp, a frequency correction value, and a synchronization quality index. Based on the synchronization confirmation message, the receiving device performs time and frequency synchronization confirmation on the initial communication link between the receiving device and the satellite, and generates a security parameter negotiation channel.

[0090] As an embodiment of the present invention, reference is made to... Figure 2The diagram illustrates the detailed steps of time and frequency synchronization of the initial communication link between the receiving device and the satellite based on the guiding sequence. In this embodiment, the steps include:

[0091] S101: The receiving device extracts the time synchronization symbol of each subsequence in the guide sequence, and calculates the deviation value between the local clock and the satellite clock based on the time synchronization symbol through a preset sliding window size;

[0092] In this embodiment of the invention, after receiving a sub-sequence of the corresponding service area, the receiving device begins to extract time synchronization symbols. The first 16 symbols of each sub-sequence are designated as time synchronization symbols. These symbols employ a unique PN (pseudo-random noise) sequence, exhibiting sharp autocorrelation characteristics. The receiving device utilizes a preset sliding window, with a window size of 16 symbols, sliding across the sub-sequence in steps of 1 symbol. During each sliding process, the symbols within the window are correlated with the locally stored standard time synchronization symbols. The similarity between the two is calculated using a normalized correlation coefficient formula. When the correlation coefficient reaches its maximum value, the time point corresponding to the current position of the window is the accurate position of the time synchronization symbol. By comparing this position with the time point recorded by the local clock, and considering the satellite signal propagation speed (approximately 3 × 10⁻⁶), the time synchronization symbol is determined. 8 Using the approximate distance between the satellite and the receiving device (m / s) and the known distance between the satellite and the receiving device, the deviation between the local clock and the satellite clock is calculated. For example, if the calculated time difference is 500ns, it means that the local clock is 500ns slower than the satellite clock, providing a basis for subsequent clock adjustments.

[0093] S102: Adjust the local clock of the receiving device based on the deviation value so that the time synchronization accuracy between the receiving device and the satellite reaches a preset synchronization level, and obtain the time synchronization result;

[0094] In this embodiment of the invention, the local clock of the receiving device is adjusted based on the previously calculated deviation value. The receiving device has a built-in high-precision clock module, which can perform time calibration through external control signals. The calculated deviation value is converted into a control signal that the clock module can recognize. If the local clock is slower than the satellite clock, an acceleration signal is sent to the clock module to increase its frequency by a certain percentage; if the local clock is faster than the satellite clock, a deceleration signal is sent. Taking a deviation value of 500ns as an example, the clock module fine-tunes the clock frequency by 500 × 10⁻⁶ ns within the next second based on this deviation value. -9Hz, through continuous monitoring and fine-tuning, ensures that the time synchronization accuracy between the receiving equipment and the satellite reaches the preset synchronization level, such as within 10ns. When the time deviation values ​​of multiple consecutive measurements are all within this accuracy range, the time synchronization is determined to be complete, and the time synchronization result is obtained, ensuring that the receiving equipment and the satellite are consistent on the time reference.

[0095] S103: The receiving device extracts the frequency synchronization symbol of each subsequence in the guiding sequence and estimates the frequency offset corresponding to the frequency synchronization symbol through a spectrum analysis algorithm.

[0096] In this embodiment of the invention, after time synchronization is completed, the receiving device extracts the frequency synchronization symbols of each subsequence in the guide sequence. The middle 16 symbols of each subsequence are set as the frequency synchronization symbols. A linear frequency modulation (Chirp) signal with specific spectral characteristics is used. The receiving device uses a Fast Fourier Transform (FFT) algorithm to perform spectral analysis on the frequency synchronization symbols. The received frequency synchronization symbol signal is divided into multiple data segments, each with a length of 64 sampling points. A 128-point FFT operation is performed on each data segment to obtain its spectral distribution. By analyzing the difference between the peak position of the spectrum and the peak position of the standard frequency synchronization symbol spectrum, the frequency offset corresponding to the frequency synchronization symbol is calculated using the frequency offset estimation formula. For example, if the center frequency of the standard frequency synchronization symbol is 1561.098MHz, after FFT analysis, the frequency corresponding to the peak of the received signal spectrum is 1561.09801MHz, then the frequency offset is calculated to be 10kHz, providing accurate data for subsequent frequency adjustment.

[0097] S104: Adjust the local oscillator frequency of the receiving device based on the frequency offset so that the carrier frequency synchronization accuracy between the receiving device and the satellite reaches a preset synchronization level, and obtain the frequency synchronization result;

[0098] In this embodiment of the invention, the frequency of the local oscillator of the receiving device is adjusted based on the previously calculated frequency offset. The receiving device is equipped with a programmable local oscillator, whose frequency can be precisely adjusted via digital control words. The calculated frequency offset is converted into a corresponding digital control word and sent to the local oscillator. Taking a frequency offset of 10kHz as an example, the local oscillator adjusts the control voltage of the internal voltage-controlled oscillator (VCO) according to the digital control word, thereby reducing the output frequency by 10kHz. During the adjustment process, the spectrum of the received signal is continuously monitored. When the peak value of the received signal spectrum coincides with the peak value of the standard frequency synchronization symbol spectrum, and the frequency deviation is stable within the preset synchronization level (e.g., within 1Hz), the frequency synchronization is determined to be complete, and the frequency synchronization result is obtained, ensuring precise synchronization of the carrier frequency between the receiving device and the satellite.

[0099] S105: The receiving device generates a synchronization confirmation message based on the time synchronization result and the frequency synchronization result, wherein the synchronization confirmation message includes a timestamp, a frequency correction value, and a synchronization quality index, and performs time and frequency synchronization confirmation on the initial communication link between the receiving device and the satellite based on the synchronization confirmation message, and generates a security parameter negotiation channel.

[0100] In this embodiment of the invention, the receiving device generates a synchronization confirmation message based on the time synchronization result and the frequency synchronization result. The time synchronization result includes an adjusted local clock timestamp, accurate to 1 ns; the frequency synchronization result is converted into a frequency correction value in Hz. The synchronization quality index is obtained by calculating the combined value of the time synchronization error and the frequency synchronization error using a weighted average method. The weight of the time synchronization error is set to 0.6, and the weight of the frequency synchronization error is set to 0.4. For example, if the time synchronization error is 8 ns and the frequency synchronization error is 0.8 Hz, then the synchronization quality index is 0.6 × 8 + 0.4 × 0.8 = 5.12. The timestamp, the frequency correction value, and the synchronization quality index are encapsulated into a synchronization confirmation message and sent to the satellite through the initially established communication link. After receiving the synchronization confirmation message, the satellite verifies the validity of the timestamp and the frequency correction value and compares it with its own recorded synchronization information. If all indicators meet the requirements, it is confirmed that the time and frequency synchronization between the receiving device and the satellite is successful. Based on this, both parties generate a security parameter negotiation channel, use a symmetric key encryption algorithm, such as AES-256, to negotiate the encryption key and other security parameters, and provide a guarantee for the secure transmission of subsequent satellite short message data.

[0101] Furthermore, the receiving device sends an encryption capability message to the satellite through the security parameter negotiation channel, and negotiates with the satellite to generate a session key based on the encryption capability message. Establishing an end-to-end encrypted communication channel based on the session key includes the following steps:

[0102] The receiving device generates an encryption capability message containing a list of encryption algorithms it supports, the key exchange protocol type, and the length of the security parameters.

[0103] In this embodiment of the invention, after the receiving device completes time and frequency synchronization with the satellite and establishes a security parameter negotiation channel, it begins to generate encryption capability messages. The device's built-in security module stores various encryption algorithms, key exchange protocols, and security parameter configuration options. The supported encryption algorithm list includes symmetric encryption algorithms such as AES-128, AES-256, and SM4, as well as asymmetric encryption algorithms such as RSA-2048 and ECC-P256. The key exchange protocol types cover Diffie-Hellman and ECDH (Elliptic Curve Diffie-Hellman). Regarding security parameter length, symmetric key lengths support 128 bits and 256 bits, while asymmetric key lengths support 2048 bits and 3072 bits. The security module encapsulates this information according to a specific data format. For example, using XML format, the encryption algorithm list, key exchange protocol type, and security parameter length are identified as different tags.

[0104] Preferably, the encryption capability message is sent to the satellite through the security parameter negotiation channel, and an encryption selection message returned by the satellite is received. The encryption selection message contains the specific encryption algorithm, key exchange protocol, and security parameters selected by the satellite from the encryption capability messages supported by the receiving device.

[0105] In this embodiment of the invention, the receiving device sends an encryption capability message to the satellite through an established security parameter negotiation channel. The security parameter negotiation channel employs a preliminary security protection mechanism, such as simple message authentication and integrity verification based on a preset temporary key. During transmission, the device's radio frequency module modulates the message onto a specific carrier frequency and transmits it to the satellite in the form of electromagnetic waves. After receiving the encryption capability message, the satellite's ground control center or onboard processing system selects from the encryption capability messages supported by the receiving device according to its own security policy and resource configuration. Assuming the satellite selects AES-256 as the specific encryption algorithm, Diffie-Hellman as the key exchange protocol, and the security parameter length is determined to be 256 bits, the satellite encapsulates this selection information into an encryption selection message and then returns the encryption selection message to the receiving device through the security parameter negotiation channel. The receiving device uses its radio frequency module to receive the signal and, after demodulation, decoding, and other processing, obtains the satellite's encryption selection information.

[0106] Preferably, the receiving device and the satellite negotiate and generate shared key material based on the encrypted selection message using the Diffie-Hellman key exchange algorithm;

[0107] In this embodiment of the invention, the receiving device and the satellite, based on the encrypted selection message returned by the satellite, begin negotiating and generating shared key material using the Diffie-Hellman key exchange algorithm. The Diffie-Hellman key exchange algorithm is based on the discrete logarithm problem over a finite field. The two parties first determine a set of common parameters, including a large prime number p and a generator g. These parameters are pre-defined in the standard protocol of the satellite communication system; for example, p is a 512-bit large prime number, and g = 2. The receiving device generates a random number a (assuming a = 123456) and calculates A = g. a mod p, and send A to the satellite through the security parameter negotiation channel. After receiving A, the satellite also generates a random number b (assuming b = 654321), and calculates B = g. b Mod p, then send B to the receiving device. After receiving B, the receiving device calculates the shared key material K1 = B. a mod p; After the satellite receives A, it calculates the shared key material K2 = A. b Mod p, due to mathematical principles, the values ​​of K1 and K2 are equal, thus both parties negotiate the same shared key material, laying the foundation for the subsequent generation of session keys.

[0108] Preferably, the receiving device and the satellite respectively perform hash processing on the shared key material to generate the same session key, and verify the consistency of the session key through a key confirmation mechanism;

[0109] In this embodiment of the invention, the receiving device and the satellite respectively perform hash processing on the shared key material. Both parties use the SHA-256 hash algorithm, which maps data of arbitrary length to a 256-bit hash value. Assuming the shared key material is a string "abcdef123456" containing specific values ​​and characters, the receiving device inputs it into the hash calculation module. After complex calculations, a 256-bit hash value is generated, which serves as part of the session key. The satellite performs the same SHA-256 hash operation on the same shared key material, obtaining the same 256-bit hash value, which is used to verify the session key. To ensure consistency, both parties employ a key confirmation mechanism. The receiving device selects a segment of test data in a fixed format, such as "TestData_123," and encrypts it using the generated session key via the AES-256 symmetric encryption algorithm to obtain the encrypted ciphertext. The ciphertext and the original test data are then transmitted to the satellite through a security parameter negotiation channel. Upon receiving the data, the satellite decrypts the ciphertext using its own generated session key. If the decrypted test data is completely consistent with the received original test data, it confirms that the session keys generated by both parties are the same; otherwise, the key negotiation process is repeated until the session keys are consistent.

[0110] Preferably, the receiving device and the satellite establish an end-to-end encrypted communication channel based on the session key, and the encrypted communication channel uses a symmetric encryption algorithm to encrypt and protect the transmitted data.

[0111] In this embodiment of the invention, the receiving device and the satellite establish an end-to-end encrypted communication channel based on a verified session key. During the establishment process, both parties configure the session key into their respective encryption and decryption modules. For data transmission, the AES-256 symmetric encryption algorithm is used to encrypt and protect the transmitted data. When the receiving device has short message data to send, the data first enters the encryption module. The encryption module divides the data into 128-bit data blocks according to the requirements of the AES-256 algorithm (padding is performed for blocks less than 128 bits). Then, the session key is used to perform encryption operations on each data block to generate ciphertext. The ciphertext is transmitted through the satellite communication link. After receiving the ciphertext, the satellite sends it to the decryption module. The decryption module uses the same session key and follows the decryption process of the AES-256 algorithm to decrypt the ciphertext and restore the original short message data. Throughout the communication process, the encrypted communication channel continuously performs encryption and decryption operations on the data to ensure the confidentiality and security of the satellite short message data during transmission and prevent the data from being stolen or tampered with.

[0112] Furthermore, after the receiving device sends a short message data transmission request to the satellite through the encrypted communication channel, the process further includes the following steps:

[0113] The receiving device encapsulates the short message data to be transmitted in a format to generate an original request message containing a service type identifier, service quality level parameters, and data priority markers.

[0114] In this embodiment of the invention, the receiving device acquires short message data to be transmitted, such as a message with the content "Emergency material transportation coordinates: 30.2°N, 120.5°E". The data processing module within the device encapsulates the data according to a predetermined format specification. The service type identifier is set according to the data purpose. If it is emergency rescue related data, the service type identifier is assigned the value "03" (assuming "03" represents emergency rescue service). The service quality level parameter is determined according to the urgency of the service and the data transmission requirements. For emergency rescue data, the service quality level parameter is set to "high", and the corresponding numerical code is "2". The data priority mark is represented by integers from 0 to 3, with 0 being the highest priority. The priority mark of this emergency rescue data is set to "0". The data processing module combines and encapsulates the short message data, service type identifier, service quality level parameter, and data priority mark in a fixed byte order. For example, two bytes are reserved to store the service type identifier, then two bytes are used to store the service quality level parameter code, then one byte is used to store the data priority mark, and finally the short message data is followed by it in UTF-8 encoding format to generate the original request message. If the short message data is insufficient in length, it is padded with the specific character "#" to ensure the integrity and standardization of the message format, so that the satellite can accurately parse the attributes and content of the data after receiving it.

[0115] Preferably, the original request message is digitally signed to generate a signed request message containing a message digest and a signature value, wherein the data signature is implemented using elliptic curve digital signature.

[0116] In this embodiment of the invention, the receiving device performs a digital signature operation on the generated original request message. The receiving device uses the Elliptic Curve Digital Signature Algorithm (ECDSA) based on pre-defined elliptic curve parameters (assuming the NIST-recommended P-256 curve is used, which is defined over a finite field and includes specific curve equation parameters, base point coordinates, etc.) and its own private key for signature processing. First, the original request message is hashed using the SHA-256 hash algorithm, mapping the original request message of arbitrary length to a 256-bit message digest. For example, the hashed message digest is "5a0f9c1b2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f". Then, the message digest is combined with the private key (assuming it is a 256-bit string "1234567890abcdef123456"). The message digest ("7890abcdef1234567890abcdef1234567890abcdef") and the elliptic curve digital signature algorithm are used to calculate and generate a signature value. The signature value consists of two parts, r and s, which are the coordinate values ​​on the elliptic curve obtained through a series of operations. Finally, the message digest and the signature value are combined to generate a signature request message containing complete signature information, ensuring the integrity and non-repudiation of the message and preventing the message from being tampered with during transmission.

[0117] Preferably, the signature request message is encrypted using the session key to generate an encrypted request data packet;

[0118] In this embodiment of the invention, after completing the digital signature, the receiving device encrypts the signature request message using a pre-negotiated session key (assuming the session key is "87654321fedcba9087654321fedcba90", with a length of 256 bits). The device's built-in encryption module employs the AES-256 symmetric encryption algorithm. This algorithm groups the signature request message into 128-bit blocks. If the total length of the signature request message is not a multiple of 128 bits, PKCS7 padding is used. For example, if the signature request message is 300 bits long, 12 bits need to be padded to reach 312 bits (26 128-bit blocks). The encryption module sequentially performs encryption operations on each block, using a series of complex operations such as round key addition, byte substitution, row shifting, and column mixing, encrypting each block using the session key to generate ciphertext. All the encrypted ciphertext blocks are then concatenated to form a complete encrypted request data packet, ensuring data confidentiality during transmission. Only satellites possessing the same session key can decrypt the data.

[0119] Preferably, the encrypted request data packet is sent to the satellite through the encrypted communication channel, and a request confirmation message is received from the satellite. The request confirmation message includes the request processing status and resource allocation pre-indication information.

[0120] In this embodiment of the invention, the receiving device sends an encrypted request data packet to the satellite through an established encrypted communication channel. The device's radio frequency module modulates the encrypted request data packet onto a specified carrier frequency (assumed to be the 2.4 GHz band) and transmits the signal to the satellite in the form of electromagnetic waves through an antenna. After receiving the encrypted request data packet, the satellite decrypts it using the same session key to obtain a signed request message. Then, it verifies the digital signature of the message by verifying the validity of the signature value using the sender's public key (paired with the receiving device's private key, which can be obtained from the key management center of the satellite communication system) and the message digest, confirming that the message has not been tampered with and indeed comes from a legitimate receiving device. The satellite processes the request message, allocating resources and scheduling tasks according to the service type, quality of service level, and data priority. After processing, the satellite generates a request confirmation message, in which the request processing status is represented by a specific code, such as "00" indicating successful processing and "01" indicating insufficient resources and temporary non-processing. The resource allocation pre-indication information includes estimated information such as bandwidth and storage resources allocated for the request. The satellite returns the request confirmation message to the receiving device through the encrypted communication channel. The receiving device uses the radio frequency module to receive signals. After demodulation, decryption and other processing, it obtains the request confirmation message, thereby knowing the processing status of the short message data and the expected subsequent resource allocation, so as to carry out the next operation or take corresponding processing measures.

[0121] Furthermore, the satellite, based on the short message data transmission request, allocates corresponding beam resources according to a preset resource scheduling strategy, and sends beam configuration parameters to the receiving device through the encrypted communication channel, including the following steps:

[0122] The satellite parses the short message data transmission request to extract information such as service type, quality of service level, and data priority.

[0123] In this embodiment of the invention, after receiving an encrypted request data packet from a receiving device via satellite, the satellite first decrypts it using the pre-negotiated session key to obtain a signed request message. Subsequently, the satellite verifies the signature value using its built-in digital signature verification module, leveraging the receiving device's public key and message digest. Upon successful verification, the satellite extracts the original request message from the signed request message and parses it according to a predetermined format. Taking an original request message as an example, the satellite first reads the first two bytes, parsing out the service type identifier as "03". Based on a preset service type encoding table, the satellite determines the service type of the short message data to be emergency rescue. Next, it reads the following two bytes, parsing out the service quality level parameter encoding as "2", corresponding to a "high" service quality level. Finally, it reads the next byte, obtaining the data priority marker as "0", indicating the highest priority. In this way, the satellite accurately extracts the service type, service quality level, and data priority information from the short message data transmission request, providing a basis for subsequent resource scheduling.

[0124] Preferably, according to a preset resource scheduling strategy, the corresponding beam resources are selected and allocated from the available beam resource pool within the satellite based on the service type, service quality level, and data priority information;

[0125] In this embodiment of the invention, a detailed resource scheduling strategy table is pre-set within the satellite. This table clearly defines the beam resource allocation rules corresponding to different combinations of service types, service quality levels, and data priorities. For example, for a request with an emergency rescue service type, a high service quality level, and the highest data priority, the strategy table specifies that beam resources with large bandwidth and high signal stability should be allocated first. Based on previously extracted information, the satellite selects and allocates the corresponding beam resources from the available beam resource pool. The available beam resource pool records the usage status, remaining bandwidth, center frequency, and other information of each beam on the satellite in real time. Assuming there are currently 5 beams in the available beam resource pool, numbered B1-B5, where B1 has a bandwidth of 50MHz and a center frequency of 2.4GHz; B2 has a bandwidth of 30MHz and a center frequency of 2.5GHz, etc., according to the resource scheduling strategy, the satellite determines to allocate beam resource B1 for this emergency rescue request. This beam can meet the requirements of high-priority, high-quality transmission, ensuring that short message data can be transmitted quickly and stably.

[0126] Preferably, the beam resources are configured with parameters to generate beam configuration parameters that include beam center frequency, bandwidth, modulation scheme, coding rate and power control parameters.

[0127] In this embodiment of the invention, after determining the allocation of B1 beam resources, the satellite configures the parameters of the beam resources. The satellite's beam parameter configuration module generates beam configuration parameters containing multiple key parameters based on service requirements and resource characteristics. For the beam center frequency, the original 2.4GHz of the B1 beam is maintained; the bandwidth is set to 50MHz to meet the data transmission requirements of emergency rescue; the modulation method is QPSK (quadrangular phase shift keying) with strong anti-interference capability and high transmission efficiency; the coding rate is determined to be 1 / 2 convolutional coding, which can ensure data accuracy and transmission efficiency; the power control parameters are calculated based on factors such as the distance between the receiving equipment and the satellite and environmental interference. Assuming that the initial transmit power is calculated to be 20dBm, the information such as the beam center frequency, bandwidth, modulation method, coding rate, and power control parameters are integrated and beam configuration parameters are generated according to a fixed data format. For example, using a binary encoding format, the center frequency of 2.4 GHz is first converted into the corresponding binary value. Then, the bandwidth, modulation scheme encoding (QPSK encoding is "01"), encoding rate encoding, and power control parameter encoding are combined in sequence to form a complete beam configuration parameter data string, providing accurate information for subsequent encrypted transmission and receiver equipment configuration.

[0128] Preferably, the beam configuration parameters are encrypted using the session key to generate an encrypted beam configuration data packet;

[0129] In this embodiment of the invention, the satellite uses a session key negotiated with the receiving device to encrypt the generated beam configuration parameters. The satellite's built-in encryption module also employs the AES-256 symmetric encryption algorithm, grouping the beam configuration parameter data string into 128-bit groups. If the total length of the beam configuration parameter data string is not a multiple of 128 bits, PKCS7 padding is used. Assuming the beam configuration parameter data string is 280 bits long, 32 bits need to be padded to reach 312 bits (26 128-bit groups). The encryption module performs encryption operations on each group through a series of operations such as round key addition, byte substitution, row shifting, and column mixing to generate ciphertext. The encrypted ciphertexts of all groups are then concatenated to form a complete encrypted beam configuration data packet, preventing the beam configuration parameters from being stolen or tampered with during transmission and ensuring that only legitimate receiving devices can decrypt and obtain the correct configuration information.

[0130] Preferably, the encrypted beam configuration data packet is sent to the receiving device through the encrypted communication channel, and a configuration confirmation message is received from the receiving device. The configuration confirmation message includes the reception status and adjustment suggestions corresponding to the beam configuration parameters.

[0131] In this embodiment of the invention, the satellite sends encrypted beam configuration data packets to the receiving device through an established encrypted communication channel. The satellite's radio frequency (RF) transmission module modulates the encrypted beam configuration data packets onto a carrier frequency matching the encrypted communication channel and transmits the signal to the receiving device in the form of electromagnetic waves through the satellite antenna. The receiving device receives the signal using its RF module, demodulates it, and decrypts the encrypted beam configuration data packets using a session key to obtain the beam configuration parameters. The receiving device parses and verifies the beam configuration parameters, checking whether the parameters are complete and reasonable. If the reception is successful and the parameters are correct, the reception status is marked as "00"; if some parameters are missing or incorrect, the reception status is marked as "01," and adjustment suggestions are generated based on the actual situation, such as suggesting adjusting the bandwidth to 40MHz to better match the device's receiving capabilities. The receiving device encapsulates a configuration confirmation message containing the beam configuration parameters, reception status, and adjustment suggestions, encrypts it using the session key, and returns it to the satellite through the encrypted communication channel. The satellite receives and decrypts the configuration confirmation message, determines whether the beam configuration is successful based on the reception status, and if there are adjustment suggestions, further evaluates and decides whether to adjust the beam configuration parameters to ensure that the communication resource configuration between the satellite and the receiving equipment reaches the optimal state.

[0132] Furthermore, the receiving device adjusts the corresponding receiving antenna according to the beam configuration parameters to form a directional receiving beam, and receives the short message data sent by the satellite through the directional receiving beam, including the following steps:

[0133] The receiving device parses the beam configuration parameters to extract the beam center frequency, bandwidth, modulation method, coding rate, and power control parameters.

[0134] In this embodiment of the invention, after receiving the encrypted beam configuration data packet sent by the satellite, the receiving device decrypts it using the negotiated session key. The decryption process employs the reverse operation of the AES-256 symmetric encryption algorithm, sequentially performing column mixing inverse operation, row shift inverse operation, byte substitution inverse operation, and round key addition inverse operation on the ciphertext blocks to restore the original beam configuration parameter data string. Taking the binary encoded beam configuration parameter data string "100110010001010100000001000000100000011" as an example, the receiving device first extracts the first 12 bits according to the predetermined parsing rules. The value "100110010001" is converted to a beam center frequency of 2.4GHz using a frequency encoding conversion table. The next eight bits, "01010000", are extracted, corresponding to a bandwidth of 50MHz. Then, "00000001" is extracted and parsed into QPSK modulation using a modulation scheme encoding table. "00000010" corresponds to a 1 / 2 convolutional coding rate. Finally, the last eight bits, "00000011", are converted using power control parameters to obtain an initial transmit power of 20dBm. This precise parsing process completely extracts key information from the beam configuration parameters, providing a basis for subsequent equipment parameter adjustments and signal processing.

[0135] Preferably, the physical parameters of the receiving antenna of the receiving device are adjusted according to the beam configuration parameters, including the phase distribution of the antenna array, the amplitude weighting coefficient, and the polarization direction, so as to form a directional receiving beam pointing to the satellite;

[0136] In this embodiment of the invention, the receiving device adjusts the physical parameters of the receiving antenna based on the analyzed beam configuration parameters. Taking a phased array antenna as an example, the antenna array consists of 64 antenna elements. By adjusting the phase distribution, amplitude weighting coefficient, and polarization direction of each element, a directional receiving beam pointing towards the satellite is formed. Based on the beam center frequency of 2.4 GHz and bandwidth of 50 MHz, combined with the characteristics of the antenna array, the adjustment value of the phase distribution is calculated. Assuming the antenna element spacing is 0.05 m, the required phase offset of each element is calculated using a formula. A phase shifter is then used to adjust the signal phase of each antenna element. Precise adjustments were made to ensure the antenna array's main lobe accurately points towards the satellite at its 2.4 GHz center frequency. Based on the signal quality requirements of QPSK modulation and 1 / 2 convolutional coding, a Taylor weighting algorithm was used to calculate the amplitude weighting value for each antenna element, considering the amplitude weighting coefficients. Attenuators were then used to adjust the signal amplitude of each element, optimizing the antenna array's radiation pattern, reducing sidelobe levels, and improving the ability to receive satellite signals. The polarization direction was adjusted to match the satellite's transmitted signal's polarization characteristics, ensuring maximum signal reception efficiency. Through these parameter adjustments, the receiving antenna formed a directional receiving beam that met the requirements, enhancing its ability to acquire and receive satellite signals.

[0137] Preferably, the received signal corresponding to the short message sent by the satellite is received through the directional receiving beam, and the received signal is amplified with low noise, mixed and digitized to generate a digitized received signal;

[0138] In this embodiment of the invention, the receiving device receives the short message signal transmitted by the satellite through a pre-adjusted directional receiving beam. The received signal first enters a low-noise amplifier (LNA), which has a noise figure of less than 1.5dB and a gain set to 20dB to amplify the weak received signal while minimizing noise introduction. The amplified signal then enters a mixer to be mixed with a 2.4GHz local oscillator signal generated by a local oscillator, converting the frequency of the received signal from the radio frequency band (around 2.4GHz) to the intermediate frequency band (assuming a conversion to 400MHz), facilitating subsequent processing. The mixed signal is then filtered by a bandpass filter to remove spurious signals before entering an analog-to-digital converter (ADC) for digitization. The ADC sampling rate is set to 1000MSPS (1 billion samples per second) with a resolution of 14 bits, converting the analog signal into a digital signal to generate the digitized received signal. For example, if the amplitude range of the received signal is between -1V and 1V, after ADC conversion, it becomes a series of 14-bit binary digital sequences, providing the digital signal basis for subsequent demodulation and decoding.

[0139] Preferably, the digitized received signal is demodulated and decoded according to the modulation method and coding rate in the beam configuration parameters to obtain encrypted short message data;

[0140] In this embodiment of the invention, the receiving device demodulates and decodes the digitized received signal according to the QPSK modulation scheme and 1 / 2 convolutional coding rate in the beam configuration parameters. The demodulation process employs a coherent demodulation method. First, the carrier signal is extracted from the digitized received signal. Carrier synchronization is performed through a phase-locked loop (PLL) to recover the carrier with the same frequency and phase as the transmitter. The recovered carrier is then used to coherently demodulate the digitized received signal, converting the QPSK modulated signal into a baseband signal. Next, matched filtering is applied to the baseband signal to improve the signal-to-noise ratio. For the 1 / 2 convolutional coding, Viterbi decoding is used for decoding. The Viterbi decoder is set to a depth of 7. By calculating the metric values ​​of different paths, the path with the smallest metric value is selected as the correct decoding path, restoring the encoded signal to the original encrypted short message data. For example, the received encoded data sequence "101101011100" is decoded by Viterbi to obtain the encrypted short message data sequence "01011001", thus completing the conversion of the signal from the received modulation and coding form to the encrypted data form.

[0141] Preferably, the encrypted short message data is decrypted using the session key to obtain the short message data sent by the satellite, and the integrity of the short message data is verified through an integrity check mechanism.

[0142] In this embodiment of the invention, the receiving device uses the session key negotiated with the satellite to decrypt the encrypted short message data. The decryption process also employs the AES-256 symmetric encryption algorithm. The encrypted short message data is divided into 128-bit blocks, and the reverse operation of the encryption process is performed sequentially to restore the original short message data. To verify the integrity of the short message data, a hash verification mechanism is used. The received original short message data is hashed using the SHA-256 hash algorithm, and the original hash value carried in the short message data (generated from the original data at the sending end and transmitted together) is extracted. The obtained hash value is compared with the original hash value. If they are completely identical, it indicates that the short message data has not been tampered with during transmission, and the integrity check passes. If they are inconsistent, it is determined that the data integrity has been compromised, the short message data is discarded, and a retransmission request is sent to the satellite. For example, if the calculated hash value is "5a0f9c1b2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f", which is the same as the original hash value, it is confirmed that the received short message data is complete and usable, and subsequent data processing and applications can be performed.

[0143] Furthermore, the adjustment process of the phase distribution is specifically as follows:

[0144] The beam center frequency in the beam configuration parameters is analyzed to determine the operating frequency of the antenna array, and the wavelength of the electromagnetic wave corresponding to the receiving antenna in free space is calculated based on the operating frequency.

[0145] In this embodiment of the invention, after the receiving device analyzes the beam configuration parameters, it extracts the beam center frequency information from them. Assuming the extracted beam center frequency is 2.4 GHz, this is used as the operating frequency of the antenna array. According to the formula for the propagation speed of electromagnetic waves in free space, c = λf (where c is the speed of light, approximately 3 × 10⁻⁶ GHz),... 8 Given m / s, λ is the wavelength, and f is the frequency, calculate the wavelength of the electromagnetic wave in free space corresponding to the receiving antenna. The frequency f = 2.4 × 10⁻⁶ m / s. 9 Substituting Hz into the formula, we get λ = 0.125m. During the calculation, the device's built-in high-precision calculator is used to ensure that the wavelength calculation result is accurate to three decimal places, providing an accurate wavelength data basis for subsequent antenna array parameter adjustments.

[0146] Preferably, the wavelength of the electromagnetic wave in free space is analyzed spatially based on the bandwidth in the beam configuration parameters to obtain wavelength spatial angle information, including azimuth and elevation angles.

[0147] In this embodiment of the invention, spatial angle resolution is performed on the calculated wavelength based on the bandwidth information in the beam configuration parameters. Assuming a bandwidth of 50MHz, and using a wavelength of 0.125m corresponding to a beam center frequency of 2.4GHz as a reference, the angle resolution is performed using the spatial spectrum estimation method in array signal processing. The receiving device has a built-in dedicated signal processing chip and uses the MUSIC (Multiple Signal Classification) algorithm for calculation. This algorithm constructs a spatial spectrum function by performing eigenvalue decomposition on the covariance matrix of the received signal, and then searches for the peak value of the spatial spectrum function to determine the incident electromagnetic wave. In practice, the signal processing chip divides the received signal into multiple frequency sub-bands according to the bandwidth, and performs spatial spectrum estimation for each sub-band. For example, the dedicated signal processing chip built into the receiver first divides the received signal into multiple frequency sub-bands according to a 50MHz bandwidth. Assuming it is divided into 10 sub-bands, each with a bandwidth of 5MHz, a received signal model is established for each sub-band signal. Suppose the antenna array has M = 64 elements and there are D incident signals (assuming D = 1, i.e., only the signals sent by the satellite are considered), and the azimuth angle of the d-th signal is θ. d The pitch angle is The signal x received by the m-th array element m (t) can be expressed as Where sd (t) is the complex envelope of the d-th signal. It is the array manifold vector of the m-th array element with respect to the d-th signal, n m (t) is additive white Gaussian noise. Next, the covariance matrix of the received signal is calculated as R = E[x(t)x H [(t)], where x(t) is the received signal vector, E[·] represents the mathematical expectation, and H represents the conjugate transpose. Since the mathematical expectation cannot be obtained in practice, the sample covariance matrix is ​​used by sampling the signal multiple times (assuming N = 1024 samplings). Approximate the covariance matrix R, for the covariance matrix Perform eigenvalue decomposition to obtain Where U=[u1,u2,…,u M ] is the eigenvector matrix, ∑=diag(λ1,λ2,…,λ M Let be an eigenvalue diagonal matrix, and let the eigenvalues ​​be ordered in descending order: λ1≥λ2≥…≥λ M The eigenvectors corresponding to the first D larger eigenvalues ​​span the signal subspace U. s =[u1,u2,…,u D The eigenvectors corresponding to the remaining MD smaller eigenvalues ​​span the noise subspace U. n =[u D+1 ,u D+2 ,…,u M Constructing the spatial spectral function in These are different azimuth angles θ and elevation angles. The array manifold vector, within a certain angular range (azimuth range set to 0°-360°, pitch range set to 0°-90°), traverses different θ and θ' values ​​with a step size of 0.1°. Calculate the corresponding spatial spectral function value, search for the peak value of the spatial spectral function, and find the θ and θ corresponding to the maximum value of the spatial spectral function. This refers to the estimated azimuth and elevation angles of the incident electromagnetic wave. For example, the spatial spectrum function is calculated to reach its maximum value at an azimuth angle of 30° and an elevation angle of 45°, thus determining that the azimuth angle of the incident electromagnetic wave in that sub-band signal is 30° and the elevation angle is 45°. The same calculation process is performed on all sub-bands to finally obtain the azimuth and elevation angle information of the incident electromagnetic wave within the entire bandwidth, providing a reliable basis for subsequently determining the direction vector of the antenna array.

[0148] Preferably, the direction vector of the antenna array in the corresponding coordinate system is determined according to the wavelength spatial angle information, and the dot product of the direction vector and the position coordinates of each element in the antenna array in the coordinate system is calculated to obtain the dot product between the direction vector and the position of each element.

[0149] In this embodiment of the invention, the direction vector in the coordinate system corresponding to the antenna array is determined based on the previously obtained wavelength spatial angle information. Assuming the antenna array uses a Cartesian coordinate system with the center of the antenna array as the origin, the direction vectors corresponding to the azimuth angle of 30° and the elevation angle of 45° in the Cartesian coordinate system are expressed as (sin45°cos30°, sin45°sin30°, cos45°). The direction vector is then calculated using trigonometric functions. The antenna array consists of 64 elements. The position coordinates of each element in the coordinate system are pre-set and stored in the device's memory. For example, the coordinates of the first element are (0.05, 0, 0), the coordinates of the second element are (0, 0.05, 0), and so on. The direction vector is then multiplied by the dot product of the position coordinates of each element. Taking the first element as an example, the dot product is... The dot product of each of the 64 array elements is calculated sequentially to obtain the dot product data between the direction vector and the position of each array element. This data reflects the positional relationship of each array element relative to the incident signal direction and provides key data for calculating the phase offset.

[0150] Preferably, the phase offset of each element is calculated based on the wavelength and the dot product between the direction vector and the position of each element, and the phase distribution of the antenna array is adjusted according to the phase offset.

[0151] In this embodiment of the invention, the phase offset of each array element is calculated based on the previously calculated wavelength of 0.125m and the dot product between the direction vector and the position of each array element. The phase offset is then calculated using the formula... (in Let λ be the phase offset, λ be the wavelength, and d be the dot product of the direction vector and the element position. Taking the first element as an example, its dot product is... Substituting into the formula, we can obtain the phase shift as: After calculating the phase offset of each of the 64 array elements in radians, the phase of each element is adjusted by a phase shifter in the antenna array. The phase shifter has an accuracy of 0.01 radians. The phase of each element is adjusted to the calculated phase offset value, thereby adjusting the phase distribution of the antenna array. After the adjustment is completed, the antenna array can make the signals transmitted or received by each element interfere and superimpose in space according to the calculated phase offset, forming a directional beam pointing to the satellite, enhancing the ability to receive satellite signals, and ensuring that satellite short message data can be received accurately and efficiently.

[0152] Furthermore, the satellite monitors the resource usage status of each directional receiving beam in real time. When the utilization rate of the beam resources in the resource usage status reaches a preset threshold, a resource reallocation mechanism is triggered to dynamically adjust the beam resources occupied by low-priority services to be used by high-priority services. This includes the following steps:

[0153] The satellite continuously collects the resource usage status corresponding to each directional receiving beam, including beam occupancy time, beam transmission rate, bit error rate, and signal strength;

[0154] In this embodiment of the invention, the resource management process for directional receiving beams in the satellite short message data transmission system begins with this step. This step requires the satellite to continuously collect the resource usage status corresponding to each directional receiving beam. In actual operation, the signal processing unit onboard the satellite collects key parameters of each directional receiving beam in real time through a dedicated monitoring circuit. The monitoring of beam occupancy time is achieved using a high-precision timer. This timer starts when the beam begins transmitting data and stops when the transmission ends, accurately recording the duration of each transmission and calculating the total occupancy time by accumulating the data. The beam transmission rate is calculated based on the parsing of physical layer data frames, determined by analyzing the number of bits successfully transmitted per unit time. Specifically, a sliding window algorithm is used, with a 100ms interval. The sampling period is used to calculate the average transmission rate within each period. Bit error rate (BER) monitoring is achieved through a cyclic redundancy check (CRC) mechanism, comparing the difference between the decoded data packets at the receiving end and the original data packets. The BER is calculated every 1000 data packets. Signal strength measurement relies on the power detection circuit of the RF front end, which converts the received RF signal into a voltage value and then into a digital signal strength value in dBm via an analog-to-digital converter (ADC). These parameters are sampled at a frequency of 10Hz to ensure timely capture of changes in beam resource usage. All collected data is stored in the satellite's cache and indexed by beam ID and timestamp, providing basic data for subsequent resource utilization calculations.

[0155] Preferably, the utilization rate of beam resources corresponding to each directional receiving beam is calculated based on the resource usage status and compared with a preset utilization rate threshold. When the utilization rate of beam resources reaches or exceeds the preset utilization rate threshold, a resource reallocation mechanism is triggered and a resource reallocation trigger signal is generated.

[0156] In this embodiment of the invention, the beam resource utilization rate corresponding to each directional receiving beam is calculated based on previously collected resource usage status, and compared with a preset utilization rate threshold. The resource utilization rate is calculated using a weighted comprehensive evaluation model, where the weight of beam occupancy time is 0.4, the weight of beam transmission rate is 0.3, the weight of bit error rate is 0.2, and the weight of signal strength is 0.1. The specific calculation formula is: Resource utilization rate = 0.4 × (actual occupancy time / maximum available time) + 0.3 × (actual transmission rate / maximum theoretical rate) + 0.2 × (1 - bit error rate) + 0.1 × (actual signal strength / maximum signal strength), where the maximum available time... Based on the satellite orbit period and beam coverage, the maximum theoretical rate is determined by the physical layer modulation and demodulation scheme, the maximum signal strength is the saturation receiving power of the RF front end, and the preset utilization threshold is set to 0.85. This threshold is determined by analyzing the historical operating data of the system and combining it with the reliability requirements of the satellite communication system. When the calculated beam resource utilization reaches or exceeds 0.85, the signal processing unit immediately triggers the resource reallocation mechanism and generates a resource reallocation trigger signal. This trigger signal contains information such as beam ID, current resource utilization, and resource usage status parameters, and is transmitted to the resource management unit through a dedicated control bus to provide a basis for subsequent service priority evaluation.

[0157] Preferably, based on the resource reallocation trigger signal, all services currently occupying the beam resources are prioritized to determine a list of low-priority services and a list of high-priority services;

[0158] In this embodiment of the invention, priority assessment is performed on all services currently occupying the beam resources based on a resource reallocation trigger signal. After receiving the trigger signal, the resource management unit first extracts all service information currently carried by the beam from the service scheduling database, including service ID, service type, service quality level, data transmission volume, and transmission time requirements. Service types are divided into four categories: voice communication, image transmission, short text messages, and control commands. Service quality levels are divided into 1-5 levels, with level 1 being the highest priority and level 5 being the lowest priority. The priority assessment adopts a multi-factor decision model, comprehensively considering the weight of service type (0.5), service quality level (0.3), data transmission volume (0.1), and transmission time requirements. The time requirement weight is 0.1. The specific evaluation formula is: Priority Score = 0.5 × Service Type Coefficient + 0.3 × (6 - Service Quality Level) + 0.1 × (1 - Data Transmission Volume / Maximum Transmission Volume) + 0.1 × (1 - Remaining Transmission Time / Total Transmission Time). The service type coefficient is set according to the urgency and importance of the service: 5 for voice communication, 4 for control commands, 3 for image transmission, and 2 for short text messages. Based on the priority score, all services are divided into a high-priority service list (score ≥ 3.5) and a low-priority service list (score < 3.5). This evaluation process is completed within 100ms to ensure timely response to resource shortages and provide accurate service priority information for subsequent resource reallocation.

[0159] Preferably, the maximum allowable service degradation range for each low-priority service in the low-priority service list is determined according to the resource reallocation mechanism based on the corresponding service type and service quality level. The beam resources occupied by the low-priority services are gradually released in descending order of the maximum service degradation range, and the released beam resources are redistributed to the corresponding high-priority services in the high-priority service list. At the same time, the service quality status of the downgraded low-priority services is continuously monitored. When sufficient beam resources are detected, the service recovery process is triggered to gradually restore the downgraded low-priority services according to the preset recovery strategy.

[0160] In this embodiment of the invention, the maximum allowable service degradation range for each low-priority service in the low-priority service list is determined by analyzing the corresponding service type and service quality level according to the resource reallocation mechanism. The resource management unit first establishes a degradation strategy table for each service type and service quality level combination. This table is pre-stored in the system's read-only memory. The degradation strategy table defines the maximum allowable degradation range for different services under different service quality levels. For example, for voice communication services at service quality level 4, the maximum allowable reduction in encoding rate is from 16kbps to 8kbps, and the packet loss tolerance is increased from 2% to 5%; for image transmission services at service quality level 5, the maximum allowable reduction in image resolution is from 1024×768 to 640×480, and compression... The ratio was increased from 1:10 to 1:20. After determining the maximum service degradation range for each low-priority service, the low-priority services were sorted in descending order of their maximum service degradation range. The resource management unit sent a degradation instruction to the first low-priority service in the sorted list through the service control interface. This instruction contained specific degradation parameters, such as coding rate adjustment value and resolution adjustment value. After receiving the degradation instruction, the service processing unit immediately adjusted the service processing parameters and released the corresponding beam resources. The released beam resources were redistributed to the highest priority service in the high-priority service list that did not meet the resource requirements. During the resource redistribution process, the signal processing unit continuously monitored the service quality status of the downgraded low-priority services, including parameters such as actual transmission rate, bit error rate, and latency. When beam resource utilization is detected to drop below 0.7, beam resources are considered sufficient, triggering the service recovery process. The service recovery process follows a preset recovery strategy, which is the opposite of the degradation strategy. It gradually restores the degraded low-priority services in ascending order of maximum service degradation. During the recovery process, only a portion of the service quality of one service is restored at a time, such as increasing the coding rate by half. Then, the system resource usage status is monitored for 500ms to ensure that restoring too many services at once will not cause resource strain again. The entire resource reallocation and service recovery process forms a closed-loop control, ensuring that the satellite short message data transmission system can prioritize the service quality of high-priority services when resources are scarce, and promptly restore the service quality of low-priority services when resources are sufficient.

[0161] Furthermore, the present invention also provides a satellite short message data transmission apparatus for performing the satellite short message data transmission method described above, the satellite short message data transmission apparatus comprising:

[0162] The satellite communication establishment module is used for the receiving device to establish an initial communication link with the satellite through a preset guidance sequence, and to perform time and frequency synchronization of the initial communication link between the receiving device and the satellite based on the guidance sequence, thereby generating a security parameter negotiation channel; the receiving device sends an encryption capability message to the satellite through the security parameter negotiation channel, and negotiates and generates a session key with the satellite based on the encryption capability message, and establishes an end-to-end corresponding encrypted communication channel according to the session key;

[0163] The transmission request sending module is used for the receiving device to send a short message data transmission request to the satellite through the encrypted communication channel. The short message data transmission request includes service type, service quality level and data priority information.

[0164] The transmission beam configuration module is used by the satellite to allocate corresponding beam resources according to a preset resource scheduling strategy based on the short message data transmission request, and to send beam configuration parameters to the receiving device through the encrypted communication channel.

[0165] The directional short message receiving module is used by the receiving device to adjust the corresponding receiving antenna according to the beam configuration parameters to form a directional receiving beam, and to receive the short message data sent by the satellite through the directional receiving beam;

[0166] The beam resource reconfiguration module is used for satellite real-time monitoring of the resource usage status corresponding to each directional receiving beam. When the utilization rate of the beam resource in the resource usage status reaches a preset threshold, the resource reconfiguration mechanism is triggered to dynamically adjust the beam resources occupied by low-priority services to be used by high-priority services.

[0167] Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the application are intended to be included within the invention.

[0168] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A satellite short message data transmission method, characterized in that, Includes the following steps: The receiving device establishes an initial communication link with the satellite through a preset guiding sequence. The receiving device extracts the time synchronization symbol of each subsequence in the guiding sequence and calculates the deviation value between the local clock and the satellite clock based on the time synchronization symbol through a preset sliding window size. The local clock of the receiving device is adjusted based on the deviation value to achieve a preset synchronization level between the receiving device and the satellite, and a time synchronization result is obtained. The receiving device extracts the frequency synchronization symbols of each sub-sequence in the pilot sequence and estimates the frequency offset corresponding to the frequency synchronization symbols using a spectrum analysis algorithm. The local oscillator frequency of the receiving device is adjusted based on the frequency offset to achieve a preset synchronization level between the receiving device and the satellite, and a frequency synchronization result is obtained. The receiving device generates a synchronization confirmation message based on the time synchronization result and the frequency synchronization result. The synchronization confirmation message includes a timestamp, a frequency correction value, and a synchronization quality index. Based on the synchronization confirmation message, the initial communication link between the receiving device and the satellite is synchronized for time and frequency, and a security parameter negotiation channel is generated. The receiving device sends an encryption capability message to the satellite through the security parameter negotiation channel, and negotiates with the satellite to generate a session key based on the encryption capability message, and establishes an end-to-end corresponding encrypted communication channel according to the session key; The receiving device sends a short message data transmission request to the satellite through the encrypted communication channel. The short message data transmission request includes service type, quality of service level, and data priority information. Based on the short message data transmission request, the satellite allocates corresponding beam resources according to a preset resource scheduling strategy and sends beam configuration parameters to the receiving device through the encrypted communication channel; The receiving device adjusts the corresponding receiving antenna according to the beam configuration parameters to form a directional receiving beam, and receives the short message data sent by the satellite through the directional receiving beam; The satellite monitors the resource usage status of each directional receiving beam in real time. When the beam resource utilization rate reaches a preset threshold, a resource reallocation mechanism is triggered, and a resource reallocation trigger signal is generated. According to the resource reallocation mechanism, the maximum allowable service degradation range for each low-priority service in the low-priority service list is determined based on the corresponding service type and service quality level. The beam resources occupied by the low-priority services are gradually released in descending order of the maximum service degradation range, and the released beam resources are redistributed to the corresponding high-priority services in the high-priority service list. At the same time, the service quality status of the downgraded low-priority services is continuously monitored. When sufficient beam resources are detected, a service recovery process is triggered to gradually restore the downgraded low-priority services according to a preset recovery strategy.

2. The satellite short message data transmission method according to claim 1, characterized in that, The guiding sequence adopts an orthogonal sequence set with zero correlation region characteristics. The orthogonal sequence set includes multiple mutually orthogonal sub-sequences, each of which corresponds to a different satellite service area, and is used to realize the rapid association between the receiving device and the target satellite.

3. The satellite short message data transmission method according to claim 1, characterized in that, The receiving device sends an encryption capability message to the satellite through the security parameter negotiation channel, and negotiates with the satellite to generate a session key based on the encryption capability message. Establishing an end-to-end encrypted communication channel based on the session key includes the following steps: The receiving device generates an encryption capability message containing a list of encryption algorithms it supports, the key exchange protocol type, and the length of the security parameters. The encryption capability message is sent to the satellite through the security parameter negotiation channel, and the encryption selection message returned by the satellite is received. The encryption selection message contains the specific encryption algorithm, key exchange protocol and security parameters selected by the satellite from the encryption capability messages supported by the receiving device. The receiving device and the satellite negotiate and generate shared key material based on the encrypted selection message using the Diffie-Hellman key exchange algorithm. The receiving device and the satellite respectively perform hash processing on the shared key material to generate the same session key, and verify the consistency of the session key through a key confirmation mechanism; The receiving device and the satellite establish an end-to-end encrypted communication channel based on the session key. The encrypted communication channel uses a symmetric encryption algorithm to encrypt and protect the transmitted data.

4. The satellite short message data transmission method according to claim 3, characterized in that, After the receiving device sends a short message data transmission request to the satellite through the encrypted communication channel, the following steps are also included: The receiving device encapsulates the short message data to be transmitted in a format to generate an original request message containing a service type identifier, service quality level parameters, and data priority markers. The original request message is digitally signed to generate a signed request message containing a message digest and a signature value. The data signature is implemented using elliptic curve digital signature. The signature request message is encrypted using the session key to generate an encrypted request data packet; The encrypted request data packet is sent to the satellite through the encrypted communication channel, and a request confirmation message is received from the satellite. The request confirmation message contains the request processing status and resource allocation pre-indication information.

5. The satellite short message data transmission method according to claim 4, characterized in that, The satellite, based on the short message data transmission request, allocates corresponding beam resources according to a preset resource scheduling strategy, and sends beam configuration parameters to the receiving device through the encrypted communication channel, including the following steps: The satellite parses the short message data transmission request to extract information such as service type, quality of service level, and data priority. According to the preset resource scheduling strategy, the corresponding beam resources are selected and allocated from the available beam resource pool within the satellite based on the service type, service quality level, and data priority information. The beam resources are configured with parameters to generate beam configuration parameters that include beam center frequency, bandwidth, modulation scheme, coding rate and power control parameters. The beam configuration parameters are encrypted using the session key to generate an encrypted beam configuration data packet; The encrypted beam configuration data packet is sent to the receiving device through the encrypted communication channel, and a configuration confirmation message is received from the receiving device. The configuration confirmation message includes the reception status and adjustment suggestions corresponding to the beam configuration parameters.

6. The satellite short message data transmission method according to claim 5, characterized in that, The receiving device adjusts the corresponding receiving antenna according to the beam configuration parameters to form a directional receiving beam, and receives the short message data sent by the satellite through the directional receiving beam, including the following steps: The receiving device parses the beam configuration parameters to extract the beam center frequency, bandwidth, modulation method, coding rate, and power control parameters. The physical parameters of the receiving antenna of the receiving device are adjusted according to the beam configuration parameters, including the phase distribution of the antenna array, the amplitude weighting coefficient and the polarization direction, so as to form a directional receiving beam pointing to the satellite. The directional receiving beam receives the received signal corresponding to the short message sent by the satellite, and performs low-noise amplification, mixing and digitization processing on the received signal to generate a digitized received signal. The digitized received signal is demodulated and decoded according to the modulation method and coding rate in the beam configuration parameters to obtain encrypted short message data; The encrypted short message data is decrypted using the session key to obtain the short message data sent by the satellite, and the integrity of the short message data is verified through an integrity check mechanism.

7. The satellite short message data transmission method according to claim 6, characterized in that, The adjustment process of the phase distribution is as follows: The beam center frequency in the beam configuration parameters is analyzed to determine the operating frequency of the antenna array, and the wavelength of the electromagnetic wave corresponding to the receiving antenna in free space is calculated based on the operating frequency. Based on the bandwidth in the beam configuration parameters, the wavelength of the electromagnetic wave in free space is analyzed spatially to obtain wavelength spatial angle information, including azimuth and elevation angles. The direction vector of the antenna array in the corresponding coordinate system is determined based on the wavelength spatial angle information, and the dot product between the direction vector and the position coordinates of each element in the antenna array in the coordinate system is calculated to obtain the dot product between the direction vector and the position of each element. Based on the wavelength and the dot product between the direction vector and the position of each element, the phase offset of each element is calculated, and the phase distribution of the antenna array is adjusted according to the phase offset.

8. The satellite short message data transmission method according to claim 1, characterized in that, The satellite monitors the resource usage status of each directional receiving beam in real time. When the utilization rate of the beam resources in the resource usage status reaches a preset threshold, the resource reallocation mechanism is triggered, which also includes the following steps: The satellite continuously collects the resource usage status corresponding to each directional receiving beam, including beam occupancy time, beam transmission rate, bit error rate, and signal strength; Based on the resource usage status, the beam resource utilization rate corresponding to each directional receiving beam is calculated and compared with a preset utilization rate threshold. When the beam resource utilization rate is detected to reach or exceed the preset utilization rate threshold, the resource reallocation mechanism is triggered and a resource reallocation trigger signal is generated. Based on the resource reallocation trigger signal, all services currently occupying the beam resources are prioritized to determine the list of low-priority services and the list of high-priority services.

9. A satellite short message data transmission device, characterized in that, For performing the satellite short message data transmission method as described in claim 1, the satellite short message data transmission device includes: The satellite communication establishment module is used for the receiving device to establish an initial communication link with the satellite through a preset guidance sequence, and to perform time and frequency synchronization of the initial communication link between the receiving device and the satellite based on the guidance sequence, thereby generating a security parameter negotiation channel; the receiving device sends an encryption capability message to the satellite through the security parameter negotiation channel, and negotiates and generates a session key with the satellite based on the encryption capability message, and establishes an end-to-end corresponding encrypted communication channel according to the session key; The transmission request sending module is used for the receiving device to send a short message data transmission request to the satellite through the encrypted communication channel. The short message data transmission request includes service type, service quality level and data priority information. The transmission beam configuration module is used by the satellite to allocate corresponding beam resources according to a preset resource scheduling strategy based on the short message data transmission request, and to send beam configuration parameters to the receiving device through the encrypted communication channel. The directional short message receiving module is used by the receiving device to adjust the corresponding receiving antenna according to the beam configuration parameters to form a directional receiving beam, and to receive the short message data sent by the satellite through the directional receiving beam; The beam resource reconfiguration module is used for satellite real-time monitoring of the resource usage status corresponding to each directional receiving beam. When the utilization rate of the beam resource in the resource usage status reaches a preset threshold, the resource reconfiguration mechanism is triggered to dynamically adjust the beam resources occupied by low-priority services to be used by high-priority services.

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