Cooperative transmission method, device and equipment of low earth orbit satellite network and storage medium

Abstract

The invention discloses a cooperative transmission method, device and equipment of a low earth orbit satellite network and a storage medium, relates to the technical field of multi-satellite cooperative transmission, and discloses the cooperative transmission method of the low earth orbit satellite network, which comprises the following steps: when a multi-satellite cooperative transmission request sent by a mobile terminal is received, sending the multi-satellite cooperative transmission request to the mobile terminal; determining collaborative auxiliary satellites according to the positioning information of the mobile terminal and ephemeris information of the low-orbit satellite network; starting a collaborative session with the collaborative auxiliary satellite according to the mobile terminal information of the mobile terminal; switching the current waveform modulation mode from orthogonal frequency division multiplexing to a target modulation mode, and converting the service data packet into a target service waveform according to the target modulation mode; performing compensation processing on the target service waveform to obtain a time-frequency compensation signal and a multi-path waveform signal; and sending the multi-path waveform signal to the mobile terminal, and sending the time-frequency compensation signal to the cooperative auxiliary satellite according to the cooperative session to obtain service data, thereby completing cooperative transmission of the low-orbit satellite network. And the stability and effectiveness of multi-satellite cooperative transmission can be ensured.

Description

Technical Field

[0001] This application relates to the field of multi-satellite cooperative transmission technology, and in particular to cooperative transmission methods, apparatus, equipment and storage media for low-Earth orbit satellite networks. Background Technology

[0002] In the current trend of mobile communication development, low-Earth orbit (LEO) satellites are gradually becoming an important means of expanding global network coverage and enhancing long-distance communication capabilities. Especially in applications where mobile phones directly connect to satellites, LEO satellites can provide continuous, wide-area communication services to remote areas, oceans, and disaster-prone regions. However, in these scenarios, the limited antenna capabilities of mobile terminals make it difficult to achieve high-speed, high-bandwidth transmission in the downlink user link.

[0003] Existing traditional methods primarily compensate for the shortcomings of mobile terminals by improving satellite-side resource allocation, such as increasing the gain of satellite antennas or increasing the number of satellites in orbit, in order to improve the overall link throughput performance. While improving satellite-side resource allocation can enhance downlink transmission capacity to some extent, it significantly increases the construction and operation costs of satellite networks, making it difficult to apply to large-scale scenarios.

[0004] The above content is only used to help understand the technical solution of this application and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main objective of this application is to provide a collaborative transmission method, apparatus, device, and storage medium for low-Earth orbit satellite networks, aiming to solve the technical problem that the downlink cannot stably achieve high-speed and high-bandwidth transmission in scenarios where mobile phones are directly connected to low-Earth orbit satellites.

[0006] To achieve the above objectives, this application proposes a cooperative transmission method for low-Earth orbit satellite networks, the method comprising: Upon receiving a multi-satellite collaborative transmission request from a mobile terminal, the auxiliary satellites for collaboration are determined based on the mobile terminal's positioning information and the ephemeris information of the low-Earth orbit satellite network. A collaborative session with the auxiliary satellite is initiated based on the mobile terminal information of the mobile terminal. Upon receiving a service data packet, the current waveform modulation mode is switched from orthogonal frequency division multiplexing to the target modulation mode, and the service data packet is converted into a target service waveform according to the target modulation mode. The target modulation mode includes orthogonal time-frequency control or simulated radio frequency division multiplexing. The target service waveform is compensated to obtain a time-frequency compensated signal and a multi-channel waveform signal; The multi-channel waveform signals are sent to the mobile terminal, and the time-frequency compensation signal is sent to the cooperative auxiliary satellite according to the cooperative session, so that the mobile terminal can obtain service data based on the multi-channel waveform signals and the time-frequency compensation signal, and complete the cooperative transmission of the low-Earth orbit satellite network. The service data is obtained by the cooperative auxiliary satellite forwarding the time-frequency compensation signal to the mobile terminal according to the cooperative session, and the mobile terminal parsing the multi-channel waveform signals and the time-frequency compensation signal.

[0007] In addition, to achieve the above objectives, this application also proposes a cooperative transmission device for a low-Earth orbit satellite network, the cooperative transmission device for a low-Earth orbit satellite network comprising: a secondary satellite determination module, used to determine a cooperative secondary satellite based on the positioning information of the mobile terminal and the ephemeris information of the low-Earth orbit satellite network when receiving a multi-satellite cooperative transmission request sent by a mobile terminal; The session initiation module is used to initiate a collaborative session with the collaborative auxiliary satellite based on the mobile terminal information of the mobile terminal. The waveform conversion module is used to switch the current waveform modulation mode from orthogonal frequency division multiplexing to orthogonal time-frequency control or simulated radio frequency division multiplexing when a service data packet is received, to obtain the target modulation mode, and to convert the service data packet into a target service waveform according to the target modulation mode; The signal compensation module is used to perform compensation processing on the target service waveform to obtain a time-frequency compensated signal and a multi-channel waveform signal; The service transmission module is used to send the multi-channel waveform signals to the mobile terminal and, according to the cooperative session, send the time-frequency compensation signal to the cooperative auxiliary satellite, so that the mobile terminal can obtain service data based on the multi-channel waveform signals and the time-frequency compensation signal, and complete the cooperative transmission of the low-Earth orbit satellite network. The service data is obtained by the cooperative auxiliary satellite forwarding the time-frequency compensation signal to the mobile terminal according to the cooperative session, and the mobile terminal parsing the multi-channel waveform signals and the time-frequency compensation signal.

[0008] Furthermore, to achieve the above objectives, this application also proposes a cooperative transmission device for a low-Earth orbit satellite network, the device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the cooperative transmission method for a low-Earth orbit satellite network as described above.

[0009] In addition, to achieve the above objectives, this application also proposes a storage medium, which is a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the steps of the cooperative transmission method for low-Earth orbit satellite networks as described above.

[0010] In addition, to achieve the above objectives, this application also provides a computer program product, which includes a computer program that, when executed by a processor, implements the steps of the cooperative transmission method for low-Earth orbit satellite networks as described above.

[0011] One or more technical solutions proposed in this application have at least the following technical effects: This technology utilizes a method that determines the auxiliary satellite based on mobile device location information and low-Earth orbit satellite network ephemeris information. It initiates a cooperative session with the auxiliary satellite based on mobile device information, switches the waveform modulation mode from orthogonal frequency division multiplexing (OFDM) to orthogonal time-frequency modulation (TFM) or simulated radio frequency division multiplexing (RFD), and converts the target service waveform. The target service waveform undergoes compensation processing to obtain a time-frequency compensation signal and multiple waveform signals. These multiple waveform signals are then sent to the mobile device, and the time-frequency compensation signal is sent to the auxiliary satellite for forwarding to the mobile device according to the cooperative session. Finally, the mobile device parses the two types of signals to obtain the service data. This approach solves the problem of limited mobile device antenna capabilities in direct mobile-to-satellite connections in existing technologies. This addresses the issues of insufficient downlink transmission performance for users and the drastic increase in deployment costs for low-Earth orbit (LEO) satellite systems caused by increasing satellite antenna gain and the number of satellites. Compared to existing technologies, multi-satellite collaborative transmission improves the average signal-to-noise ratio (SNR) of mobile terminal received signals. It utilizes orthogonal time-frequency conditioning or simulated radio frequency multiplexing waveforms to combat the time-varying rapid fading caused by dynamic changes in the phase difference of multiple data streams. Compensation processing ensures that the time delay difference of each signal arriving at the mobile terminal meets transmission requirements. Without significantly increasing system deployment costs, it effectively enhances the downlink transmission performance of mobile terminals in LEO satellite networks, achieving efficient collaborative transmission in LEO satellite networks. Attached Figure Description

[0012] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0013] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a flowchart illustrating an embodiment of the cooperative transmission method for low-Earth orbit satellite networks provided in this application. Figure 2 A schematic diagram of a distributed multi-satellite collaborative architecture integrating 5G, provided in Embodiment 1 of the collaborative transmission method for low-Earth orbit satellite networks of this application; Figure 3This is a schematic diagram of the multi-satellite cooperative control plane connection architecture provided in Embodiment 1 of the cooperative transmission method for low-Earth orbit satellite networks in this application; Figure 4 A schematic diagram of the multi-satellite cooperative user plane protocol stack architecture provided in Embodiment 1 of the cooperative transmission method for low-Earth orbit satellite networks of this application; Figure 5 This is a schematic diagram of multi-satellite cooperative transmission beam control provided in Embodiment 1 of the cooperative transmission method for low-Earth orbit satellite networks in this application; Figure 6 A schematic diagram of the downlink control information waveform modulation method provided in Embodiment 1 of the cooperative transmission method for low-Earth orbit satellite networks of this application; Figure 7 This is a schematic diagram of the time-frequency arrangement of the physical downlink control channel and the physical downlink shared channel in the multi-satellite cooperative transmission mode provided in Embodiment 1 of the cooperative transmission method for low-Earth orbit satellite networks of this application. Figure 8 This is a flowchart illustrating Embodiment 2 of the cooperative transmission method for low-Earth orbit satellite networks in this application. Figure 9 This is a schematic diagram of the module structure of the cooperative transmission device for a low-orbit satellite network according to an embodiment of this application; Figure 10 This is a schematic diagram of the equipment structure of the hardware operating environment involved in the cooperative transmission method of the low-orbit satellite network in the embodiments of this application.

[0015] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0016] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0017] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0018] The main solution of this application embodiment is as follows: upon receiving a multi-satellite cooperative transmission request sent by a mobile terminal, a cooperative auxiliary satellite is determined based on the mobile terminal's positioning information and the ephemeris information of the low-Earth orbit satellite network; a cooperative session with the cooperative auxiliary satellite is initiated based on the mobile terminal information of the mobile terminal; upon receiving a service data packet, the current waveform modulation mode is switched from orthogonal frequency division multiplexing to the target modulation mode, and the service data packet is converted into a target service waveform based on the target modulation mode; the target service waveform is compensated to obtain a time-frequency compensation signal and multiple waveform signals; the multiple waveform signals are sent to the mobile terminal, and the time-frequency compensation signal is sent to the cooperative auxiliary satellite based on the cooperative session, so that the mobile terminal obtains service data based on the multiple waveform signals and the time-frequency compensation signal, thus completing the cooperative transmission of the low-Earth orbit satellite network.

[0019] In this embodiment, for ease of description, the following description will focus on the collaborative transmission equipment that identifies low-Earth orbit satellite networks.

[0020] Because existing technologies cannot stably achieve high-speed and high-bandwidth transmission in scenarios where mobile phones directly connect to low-Earth orbit satellites, this application provides a solution. This solution involves determining a cooperative auxiliary satellite based on the mobile terminal's location information and the low-Earth orbit satellite network ephemeris information. A cooperative session with the auxiliary satellite is initiated based on the mobile terminal's information. The waveform modulation method is switched from orthogonal frequency division multiplexing (OFDM) to orthogonal time-frequency modulation (TFM) or simulated radio frequency division multiplexing (RFDM), and the target service waveform is converted. The target service waveform is then compensated to obtain a time-frequency compensation signal and multiple waveform signals. These multiple waveform signals are sent to the mobile terminal, and the time-frequency compensation signal is sent to the cooperative auxiliary satellite according to the cooperative session. This technology forwards signals to the mobile terminal, which then parses the two types of signals to obtain service data. This solves the problems of insufficient downlink transmission performance in direct satellite connection scenarios where mobile phones are limited by the antenna capabilities of the mobile terminal, and the problem that increasing satellite antenna gain and the number of satellites would drastically increase the deployment cost of the low-Earth orbit satellite system. Compared with existing technologies, this technology ensures that the time delay difference of each signal arriving at the mobile terminal meets the transmission requirements through compensation processing. Without significantly increasing the system deployment cost, it effectively enhances the downlink transmission performance of the mobile terminal in the low-Earth orbit satellite network and achieves efficient collaborative transmission in the low-Earth orbit satellite network.

[0021] It should be noted that the executing entity in this embodiment can be a computing service device with data processing, network communication, and program execution functions, such as a tablet computer, personal computer, or mobile phone, or an electronic device capable of performing the above functions, a collaborative transmission device for a low-Earth orbit satellite network, or a host satellite. The following description uses a host satellite as an example to illustrate this embodiment and the subsequent embodiments.

[0022] Based on this, embodiments of this application provide a cooperative transmission method for low-Earth orbit satellite networks, referring to... Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the cooperative transmission method for low-Earth orbit satellite networks according to this application.

[0023] In this embodiment, the cooperative transmission method of the low-Earth orbit satellite network includes steps S10 to S50: Step S10: Upon receiving a multi-satellite cooperative transmission request from a mobile terminal, determine the cooperative auxiliary satellites based on the mobile terminal's positioning information and the ephemeris information of the low-Earth orbit satellite network. It should be noted that a multi-satellite collaborative transmission request is a request signal sent by a mobile device to low-Earth orbit (LEO) satellites when it requires highly reliable, high-bandwidth service transmission. The purpose is to request multiple LEO satellites to collaboratively provide transmission services, thereby improving downlink transmission performance. In this embodiment, when the mobile device has such a service requirement, it will proactively generate and send this request, triggering subsequent processes such as determining collaborative auxiliary satellites.

[0024] Furthermore, mobile terminals refer to terminal devices that require high-reliability, high-bandwidth service transmission via low-Earth orbit satellite networks, such as smartphones and portable data terminals that support non-terrestrial network (NTN) communication functions.

[0025] Additionally, mobile device location information is data used to determine the mobile device's specific location in space, typically including the mobile device's latitude and longitude coordinates and altitude. This information can be obtained through the mobile device's Global Navigation Satellite System (GNSS) module.

[0026] Additionally, ephemeris information for low-Earth orbit (LEO) satellite networks describes the orbital parameters of LEO satellites in space, including their real-time orbital position, velocity, communication payload status, and inter-satellite link bandwidth. Ephemeris information can be used to determine whether a satellite is available and whether it can meet the resource requirements for collaborative transmission.

[0027] Furthermore, auxiliary satellites are selected from low-Earth orbit (LEO) satellite networks to provide collaborative transmission services to mobile devices together with the primary satellite. Auxiliary satellites must meet conditions such as being within the mobile device's line of sight, having a satellite-to-ground link budget that meets communication requirements, and having available communication resources. Their main function is to assist the primary satellite in transmitting service data streams, improve the average signal-to-noise ratio of the signal received by the mobile device, and enhance transmission performance.

[0028] Understandably, upon receiving a multi-satellite collaborative transmission request from the mobile terminal, it indicates that the mobile terminal has a need for highly reliable and high-bandwidth service transmission. The satellite-to-ground link distance and communication angle between each low-Earth orbit satellite and the mobile terminal are calculated to filter the candidate satellite list. Low-Earth orbit satellites that have already been selected are excluded from the candidate satellite list, and at least one low-Earth orbit satellite is selected as a collaborative auxiliary satellite based on the inter-satellite link bandwidth in the ephemeris information.

[0029] Reference Figure 2 , Figure 2 This is a schematic diagram of a distributed multi-satellite collaborative architecture incorporating 5G, representing the first embodiment of the collaborative transmission method for low-Earth orbit satellite networks in this application.

[0030] like Figure 2As shown in the diagram, the system includes cooperative satellite clusters and non-cooperative satellites. The cooperative satellite cluster consists of LEO satellite 1 (primary satellite), LEO satellite 2 (secondary satellite), and LEO satellite P (secondary satellite). These secondary satellites are directly connected to the primary satellite via inter-satellite microwave links (using the 5G Xn interface protocol). The primary satellite acts as a replication and separation node for service data, responsible for copying received data packets and sending them to the secondary satellites in the cooperative satellite cluster. Terminal signaling interaction is only completed through the primary satellite, while the secondary satellites assist the primary satellite in sending service data streams. The diagram also shows the New Radio (NR) Uu interface, which is the communication interface between the handheld terminal and the satellite. The NRu interface connects to the data network through the Satellite Radio Interface (SRI) to realize the transmission of user plane data. On the ground, the core network 5GC connects to the gateway station through the N6 interface, and the gateway station then connects to the data network through the user plane interface. The entire system achieves the organic integration of 5G NTN technology and multi-satellite cooperative transmission technology through this architecture, significantly enhancing the downlink transmission performance of handheld terminals while reducing the deployment cost of multi-satellite cooperative systems, facilitating the commercialization of multi-satellite cooperative transmission technology. The cellular structure in the diagram likely represents the coverage area of ​​the terrestrial network, while the handheld terminals represent user equipment (UEs). These UEs communicate with the satellite via the NR Uu interface to achieve broadband access. Specifically, NTN represents the handheld terminal; the NR Uu interface represents the new radio interface; the NGu interface represents the new radio (NR) user plane interface; 5GC represents the 5G core network; Gateway represents the gateway; Xn interface represents the inter-satellite link interface; SRI represents the satellite radio interface; and the N6 interface represents an interface in the 5G core network used to connect user plane functions.

[0031] In one feasible implementation, step S10 may include steps S11 to S14: Step S11: When receiving a multi-satellite collaborative transmission request sent by the mobile terminal, obtain the ephemeris information, preset distance threshold and preset elevation angle threshold of the low-orbit satellites. The ephemeris information includes the real-time orbital position, communication payload status and inter-satellite link bandwidth of each low-orbit satellite. The preset distance threshold is set in advance to determine whether the distance standard of the satellite-to-ground link between the low-Earth orbit satellite and the mobile terminal meets the communication requirements. This threshold is determined based on factors such as the communication coverage capability of the low-Earth orbit satellite and the signal transmission attenuation characteristics. If the distance between the satellite and the mobile terminal is less than this threshold, it means that the signal attenuation during transmission is small; conversely, if the distance is greater than this threshold, communication may be unstable due to excessive attenuation.

[0032] The preset elevation angle threshold is a pre-set standard used to determine whether a low-orbit satellite is within the mobile device's line of sight. It is determined based on the receiving characteristics of the mobile device's antenna. The communication angle is the elevation angle of the satellite relative to the horizontal line of the mobile device. If this angle is greater than the preset elevation angle threshold, it means that the satellite is within the mobile device's line of sight. Otherwise, it may be blocked or beyond the antenna's receiving range, and normal communication will not be possible.

[0033] Step S12: Calculate the satellite-to-ground link distance and communication angle between the low-orbit satellite and the mobile terminal based on the positioning information of the mobile terminal and the real-time orbit position; It should be noted that real-time orbital position refers to the three-dimensional coordinates of a low-Earth orbit satellite in space at a specific moment. The real-time orbital position allows for precise determination of the satellite's spatial location, and combined with the mobile device's positioning information, the relative distance and angle between the two can be calculated. The communication angle is the angle between the mobile device's horizontal direction and the line connecting the low-Earth orbit satellite, calculated using the satellite's real-time orbital position and the mobile device's positioning information.

[0034] Understandably, the primary satellite extracts the mobile device's location information from previously received multi-satellite collaborative transmission requests, and simultaneously extracts the real-time orbital position of each low-Earth orbit satellite from the acquired ephemeris information. Based on spatial geometric calculation methods, the linear distance between the mobile device's location information and the satellite's real-time orbital position is calculated using two spatial points. This distance is the satellite-to-ground link distance between the low-Earth orbit satellite and the mobile device, used to determine whether the signal transmission attenuation is within an acceptable range. Also based on spatial geometric relationships, a horizontal coordinate system is established with the mobile device's location as the origin, and the elevation angle of the satellite's real-time orbital position relative to the horizontal direction of this coordinate system is calculated. This angle is the communication angle.

[0035] Step S13: Select low-Earth orbit satellites whose satellite-to-ground link distance is less than the preset distance threshold, whose communication angle is greater than the preset elevation angle threshold, and whose communication payload has idle resources to form a candidate satellite list; It should be noted that the candidate satellite list is a selection made from all low-Earth orbit satellites, chosen based on three criteria: satellite-to-ground link distance, communication angle, and communication payload resources. The satellites in this list are candidate satellites that possess the basic conditions to participate in collaborative transmission.

[0036] The existence of idle resources in the communication payload refers to the fact that the communication equipment of the low-Earth orbit satellite is not fully occupied and still has resources available to carry collaborative transmission services. In this embodiment, it mainly refers to the satellite having at least one idle service beam, because the service beam is a key device for sending service data streams to mobile terminals. Only with an idle service beam can the satellite assist the host satellite in completing the collaborative transmission task.

[0037] Understandably, each low-Earth orbit (LEO) satellite is evaluated individually. The first evaluation checks whether the satellite-to-ground link distance is less than a preset distance threshold. If it is greater than or equal to the threshold, the satellite is excluded; if it is less, the second evaluation proceeds. The second evaluation checks whether the communication angle is greater than a preset elevation angle threshold. If it is less than or equal to the threshold, the satellite is excluded; if it is greater, the third evaluation proceeds. The third evaluation checks whether there are idle resources in the communication payload, i.e., at least one idle service beam. If there are none, the satellite is excluded; if there are, the satellite is included in the candidate pool. All LEO satellites that pass the three evaluations are then compiled into a list.

[0038] Step S14: Determine a cooperative auxiliary satellite from the candidate satellite list based on the inter-satellite link bandwidth.

[0039] It should be noted that inter-satellite link bandwidth refers to the channel capacity of the inter-satellite link used for data transmission between low-Earth orbit satellites, that is, the amount of data that the inter-satellite link can transmit per unit time. In coordinated transmission, the primary satellite needs to send time-frequency compensation signals and other data to the cooperating auxiliary satellites through the inter-satellite link. The inter-satellite link bandwidth determines the data transmission rate and stability. The larger the bandwidth, the faster the data transmission rate, which better meets the needs of real-time data interaction in coordinated transmission and avoids data transmission delays or losses due to insufficient bandwidth.

[0040] The primary satellite extracts the inter-satellite link bandwidth data of each satellite in the candidate satellite list from the ephemeris information, analyzes the bandwidth in conjunction with the amount of data required for collaborative transmission, determines the bandwidth threshold that meets the requirements, and filters out candidate satellites with bandwidth greater than or equal to the threshold. If there are multiple satellites that meet the conditions, they can be sorted by bandwidth size and the satellite with larger bandwidth is selected first, as larger bandwidth can speed up data transmission and reduce interaction latency. Based on the actual collaborative transmission requirements, at least one satellite that meets the bandwidth requirements is selected as a collaborative auxiliary satellite, and its identification information is recorded to complete the determination of the collaborative auxiliary satellite.

[0041] In this embodiment, in the scenario of a mobile phone directly connecting to a low Earth orbit (LEO) satellite, the downlink suffers from the inability to stably achieve high-speed, high-bandwidth transmission. When the handheld terminal has a need for highly reliable, high-bandwidth service transmission, it first selects the satellite with the best link quality within the visible range to establish an initial connection. Then, it sequentially completes cell search, random access, radio resource control connection establishment, and non-access stratum registration to access the LEO satellite internet. Next, the terminal sends a multi-satellite collaborative transmission request (DMCT Request) to the satellite (the primary satellite). Upon receiving the request, the primary satellite, combining the terminal's positioning information and the LEO satellite network ephemeris information, searches for and calculates target auxiliary satellite resources that can participate in collaborative transmission (these resources must meet the following conditions: orbital position within the terminal's visible range, i.e., a communication angle of 30°-150°; satellite-to-ground link budget meeting communication requirements; communication payload having available resources, i.e., at least one idle service beam; and a communicable inter-satellite microwave link with the primary satellite). If the primary satellite does not find any schedulable auxiliary satellite resources, it will send a DMCTReject message to the terminal, and the terminal will only enjoy the NTN single-satellite service transmission service; if P-1 schedulable cooperative auxiliary satellite resources are found, the primary satellite will report the auxiliary satellite information to the core network, and form a master-slave cooperative satellite cluster with these auxiliary satellites.

[0042] Reference Figure 3 , Figure 3 This is a schematic diagram of the multi-satellite cooperative control plane connection architecture of the first embodiment of the cooperative transmission method for low-Earth orbit satellite networks in this application.

[0043] like Figure 3 As shown in the diagram, the 5G core network communicates with the primary satellite (Sat.1) through its next-generation core interface. The primary satellite is responsible for radio resource control and connects to the secondary satellite (Sat.2) via an inter-satellite control plane interface for inter-satellite communication and control. The secondary satellite also handles radio resource control and communicates with user equipment (UE) via a user plane radio interface. The UE contains a radio resource control module for connecting to the primary satellite. In this system, the 5G core network exchanges data with the primary satellite through the inter-satellite control plane interface, and the primary satellite then communicates with the UE through the user plane radio interface to control and manage radio resources. This architecture allows the 5G core network to extend its coverage through the satellite network, providing users with a wider range of wireless communication services. The dashed lines in the diagram represent the user plane radio interface, and the solid lines represent the control plane interface; the entire system uses these interfaces to transmit data and control radio resources.

[0044] Reference Figure 4 , Figure 4 This is a schematic diagram of the multi-satellite cooperative user plane protocol stack architecture of the first embodiment of the cooperative transmission method for low-Earth orbit satellite networks in this application.

[0045] like Figure 4As shown, the primary satellite portion begins with the Service Data Adaptation Protocol (SDAP), proceeds through Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC), and Media Access Control (MAC), reaching the Physical Layer (PHY), and then transmits signals via Radio Frequency (RF) and Antenna. The signal processing flow includes channel coding, rate matching, scrambling, constellation mapping, layer mapping, antenna precoding, and resource mapping, followed by waveform modulation. Orthogonal Frequency Division Multiplexing (OFDM), Orthogonal Time-Frequency Spatial Modulation (OTFS), or Analog Radio Division Multiplexing (AFDM) can be selected. Then, a Cyclic Prefix (CP) is added, and Sat.1 and Sat.2 are compensated by a time-frequency precompensation module. Finally, transmission occurs via the New Radio User Equipment Interface (NR Uu). The secondary satellite portion is in an idle state. Its protocol stack is similar to the primary satellite, including SDAP, PDCP, RLC, MAC, PHY, RF, and Antenna, but currently there is no active signal processing flow. The diagram also marks the separation node, which is the boundary between primary and secondary satellite signal processing. The entire system is designed to improve signal coverage and communication quality through the coordinated operation of the primary and secondary satellites, ensuring that user equipment can stably receive and transmit data via the wireless interface.

[0046] Step S20: Initiate a collaborative session with the collaborative auxiliary satellite based on the mobile terminal information of the mobile terminal; It should be noted that the collaborative session is a communication session established between the primary satellite and the collaborative auxiliary satellite to achieve collaborative transmission to the mobile terminal. This session is used to transmit control signaling and service-related information between the primary satellite and the collaborative auxiliary satellite, ensuring that the primary satellite and the collaborative auxiliary satellite coordinate their actions during the collaborative transmission process, and ensuring that service data can be transmitted to the mobile terminal in an orderly and accurate manner.

[0047] It is understandable that when the primary satellite receives the session reception message, it sends a session initiation command to the cooperating secondary satellite to initiate a cooperative session with the secondary satellite.

[0048] In one feasible implementation, step S20 may include steps S21 to S25: Step S21: Determine the identification information and location information based on the mobile terminal information of the mobile terminal; It should be noted that the identification information is used to uniquely identify the corresponding mobile terminal during low-Earth orbit satellite collaborative transmission. The positioning information is data used to determine the specific location of the mobile terminal in space; in this embodiment, it mainly refers to the mobile terminal's Global Navigation Satellite System (GNSS) location information.

[0049] Step S22: Send the identification information and the positioning information to the cooperative auxiliary satellite, so that the cooperative auxiliary satellite aligns the service beam center with the mobile terminal according to the identification information and the positioning information, and feeds back the virtual radio resource control connection established with the mobile terminal; It's important to note that the service beam is the signal beam on a low-Earth orbit satellite used to transmit service data to mobile devices. In collaborative transmission scenarios, accurately aligning the center of the service beam with the mobile device is crucial to ensuring efficient data reception and improving transmission quality. The direction of the service beam can be dynamically adjusted based on the mobile device's location information to accommodate potential changes in its position.

[0050] A virtual radio resource control connection, also known as a virtual RRC connection, is a non-physical radio resource control connection established between a secondary satellite and a mobile terminal. Unlike the real radio resource control connection established between the primary satellite and the mobile terminal, the virtual radio resource control connection does not require complex signaling interaction procedures. It is used by the secondary satellite to confirm that it is ready to provide service data transmission services to the mobile terminal, reflecting the service association status between the secondary satellite and the mobile terminal, and does not involve complete resource allocation and signaling management procedures.

[0051] The primary satellite transmits its identification and positioning information to the selected auxiliary satellites via an inter-satellite microwave link using the 5G Xn interface protocol to ensure compatibility and stability of information transmission. Upon receiving the information, the auxiliary satellites verify the identity of the mobile device requiring service based on the identification information to avoid confusion. Simultaneously, they analyze the spatial location of the mobile device based on the positioning information and activate the beam control module to adjust the service beam direction, ensuring the beam center is aligned with the mobile device to guarantee effective signal coverage. After completing beam alignment, the auxiliary satellites confirm that the basic conditions for collaborative transmission services are met, generate feedback information to establish a virtual radio resource control connection with the mobile device, and then send it to the primary satellite via the inter-satellite link to inform the primary satellite that preparations are complete.

[0052] Step S23: Upon receiving the virtual radio resource control connection, a multi-satellite cooperative transmission permission message is sent to the mobile terminal, so that the mobile terminal responds with a session establishment request message based on the multi-satellite cooperative transmission permission message; It should be noted that the multi-satellite cooperative transmission permission message is a notification message sent by the primary satellite to the mobile terminal after confirming that the cooperating secondary satellite has completed service beam alignment and established a virtual radio resource control connection. This message informs the mobile terminal that the conditions for initiating multi-satellite cooperative transmission are now met, including that the cooperating secondary satellite is ready and the transmission link is prepared. It serves as a trigger signal for the mobile terminal to initiate subsequent session establishment requests, ensuring that the mobile terminal starts subsequent processes at the appropriate time, avoiding resource waste or process confusion.

[0053] A session establishment request message is a message sent by the mobile terminal to the primary satellite after receiving a multi-satellite collaborative transmission permission message to request the establishment of a dedicated collaborative transmission session. In this embodiment, this message is specifically a collaborative transmission dedicated PDU session establishment request message, which contains information such as the mobile terminal's service requirements and the types of resources needed, providing session support for the subsequent collaborative transmission of service data.

[0054] Understandably, the primary satellite continuously monitors whether it receives virtual radio resource control connection feedback information from the cooperating secondary satellite. When this feedback information is received, it indicates that the cooperating secondary satellite has completed service beam alignment and is ready for cooperative transmission, and the overall system now has the basic conditions to start multi-satellite cooperative transmission. The primary satellite generates a multi-satellite cooperative transmission permission message, which explicitly contains the core information that the conditions for cooperative transmission are met. This message is sent to the mobile terminal through the primary satellite's signaling beam to ensure that the mobile terminal can receive the notification in a timely manner. After receiving the multi-satellite cooperative transmission permission message, the mobile terminal parses the message content to confirm that cooperative transmission can be started. It then activates its own non-access stratum module to generate a session establishment request message, which contains key information such as the service parameters required for this cooperative transmission. The mobile terminal then sends the generated session establishment request message to the primary satellite.

[0055] Step S24: Send the session establishment request message to the core network so that the core network establishes and sends back a session reception message according to the session establishment request message; It should be noted that the core network is the core control and management part of the low-Earth orbit satellite communication network, responsible for handling key functions such as signaling interaction, resource allocation, and session management. It can determine whether the resources and conditions for establishing a collaborative transmission session are available based on the session establishment request message from the mobile terminal, and is also responsible for allocating the necessary network resources for the established session to ensure its normal operation.

[0056] The session acceptance message is a confirmation message sent by the core network to the main satellite after processing the session establishment request message from the mobile terminal. In this embodiment, the message is specifically a DMCT-specific PDU Session Establishment Accept message. The message contains resource information and session parameters allocated by the core network for the collaborative transmission session, which is used to inform the main satellite core network that it has agreed to establish the collaborative transmission session and complete the relevant resource configuration.

[0057] The primary satellite sends a session establishment request message to the core network via a dedicated communication link that follows the communication protocol between low-Earth orbit satellite networks and the core network, ensuring secure and reliable message transmission. Upon receiving the message, the core network activates the session management module to analyze the mobile terminal's service requirements, the required resource types, and check its own resource status to determine whether it supports collaborative transmission session establishment. If resources are sufficient and meet the service requirements, the core network allocates network resources for the session, determines the operating parameters, and generates a session reception message. This message is then sent back to the primary satellite via the dedicated communication link, informing the primary satellite that the session establishment request has been approved and the configuration is complete.

[0058] Step S25: Upon receiving the session reception message, initiate a collaborative session with the collaborative auxiliary satellite.

[0059] Understandably, after receiving the session reception message from the core network, the primary satellite parses the message to extract key information such as session parameters and resource configuration, confirming that the core network has completed resource allocation and parameter configuration for the collaborative transmission session. Then, based on the parsed session parameters, it configures communication parameters such as the data transmission rate and signaling interaction format of the inter-satellite link between itself and the auxiliary satellite to ensure matching the collaborative session requirements. Subsequently, it sends a collaborative session initiation command containing session identifiers and parameters to the auxiliary satellite via the inter-satellite microwave link, informing it of the specific configuration and initiation requirements. After receiving the command, the auxiliary satellite configures its communication and data processing modules according to the parameters, completes the configuration, and sends confirmation information back to the primary satellite. The collaborative session between the primary and auxiliary satellites is then officially initiated, and both satellites are ready to collaboratively transmit service data, allowing them to proceed to the subsequent service data processing and transmission phase.

[0060] Reference Figure 5 , Figure 5 This is a schematic diagram of multi-satellite cooperative transmission beam control in the first embodiment of the cooperative transmission method for low-Earth orbit satellite networks of this application.

[0061] like Figure 5As shown in the diagram, the system includes cooperative satellite clusters and non-cooperative satellites. The cooperative satellite cluster consists of LEO satellite 1 (primary satellite) and LEO satellite 2 (secondary satellite), which communicate with each other via Xn over ISL (inter-satellite link) to achieve coordinated data transmission. The primary satellite is responsible for copying and separating service data and distributing it to the secondary satellites. The diagram also indicates the service beam and signaling beam, where the service beam is used to transmit user data and the signaling beam is used to transmit control signals. On the ground, the core network 5GC connects to the gateway station via the N6 interface, and the gateway station then connects to the data network via the NGu interface. Handheld terminals communicate with the satellites via the NR Uu interface to achieve broadband access. The diagram also shows the NGu over SRI (satellite radio interface) connection method, which is the user plane data transmission interface between the terrestrial network and the satellite network. The entire system achieves the organic integration of 5G NTN technology and multi-satellite cooperative transmission technology through this architecture, significantly enhancing the downlink transmission performance of handheld terminals while reducing the deployment cost of the multi-satellite cooperative system, facilitating the commercialization of multi-satellite cooperative transmission technology. The cellular structure in the diagram likely represents the coverage area of ​​the terrestrial network, while the handheld terminals represent user equipment (UEs). These UEs communicate with the satellite via the NRUu interface to achieve broadband access. Specifically, NTN represents the handheld terminal; the NR Uu interface represents the new radio interface; the NGu interface represents the new radio (NR) user plane interface; 5GC represents the 5G core network; Gateway represents the gateway; Xn interface represents the inter-satellite link interface; SRI represents the satellite radio interface; and the N6 interface represents an interface in the 5G core network used to connect user plane functions.

[0062] Step S30: When a service data packet is received, the current waveform modulation mode is switched from orthogonal frequency division multiplexing to the target modulation mode, and the service data packet is converted into a target service waveform according to the target modulation mode. The target modulation mode includes orthogonal time-frequency control or simulated radio frequency division multiplexing. It should be noted that the service data packet is a data packet containing the service data required by the mobile terminal. This data can be various types of user service data, such as video data, audio data, and file data. In this embodiment, the service data packet is sent from the core network to the main satellite. The main satellite processes the data packet and then sends it to the mobile terminal via coordinated transmission to meet the mobile terminal's service requirements.

[0063] Orthogonal Frequency Division Multiplexing (OFDM) is a waveform modulation method that divides a channel into multiple orthogonal sub-channels, transmitting independent signals on each sub-channel. This effectively combats frequency-selective fading and improves spectral efficiency. In this embodiment, OFDM is the initial waveform modulation method, used in non-cooperative transmission scenarios or under specific conditions.

[0064] The target modulation scheme is a waveform modulation method selected from orthogonal time-frequency control and simulated radio frequency multiplexing in cooperative transmission scenarios to improve the performance of service data transmission. This modulation scheme can better combat time-varying rapid fading caused by dynamic changes in the phase difference of multiple data streams.

[0065] Orthogonal Time Frequency Space (OTFS) is a waveform modulation method with two-dimensional time-frequency interleaving characteristics. It can process signals in the time and frequency domains, effectively combating channel interference such as time-varying rapid fading and Doppler frequency offset. Affine Frequency Division Multiplexing (AFDM) is also a waveform modulation method suitable for multi-satellite cooperative transmission scenarios, and it also has the characteristic of combating time-varying rapid fading.

[0066] The target service waveform is a signal waveform suitable for transmission in a channel, formed by modulating service data packets using the target modulation method. This waveform combines the advantages of the target modulation method, effectively adapting to the characteristics of cooperative transmission channels and reducing the impact of channel interference on data transmission.

[0067] It is understandable that the initial service waveform is modulated and converted according to the selected target modulation method, thus transforming the initial service waveform into the target service waveform.

[0068] In this embodiment, the primary satellite distributes the terminal's Cell Radio Network Temporary Identifier (C-RNTI) and Global Navigation Satellite System (GNSS) positioning information to the secondary satellites, and controls each secondary satellite to align its idle service beam center with the terminal. At this time, the terminal and the secondary satellites establish a virtual Radio Resource Control (RRC) connection. The primary satellite sends a multi-satellite cooperative transmission grant message (DMCTGranted) to the terminal, informing the terminal that it has met the conditions to start multi-satellite cooperative transmission. The terminal's non-access layer (NAS) generates a cooperative transmission dedicated packet data unit session establishment request message (DMCT-specific PDU Session Establishment Request) and sends it to the core network through the primary satellite. After processing the request message, the core network sends a cooperative transmission dedicated packet data unit session establishment acceptance message (DMCT-specific PDU SessionEstablishment Accept) to the terminal through the primary satellite's signaling beam. The primary satellite informs the secondary satellites through the inter-satellite link that the cooperative dedicated packet data unit session has been started. Each secondary satellite adjusts its user plane protocol stack protocol layer above the RF layer to an idle state, that is, the secondary satellite degrades from regeneration mode to transparent forwarding mode.

[0069] In one feasible implementation, step S30 may include steps S31 to S34: Step S31: Upon receiving a service data packet, the service data packet is sequentially processed by packet data aggregation, packet data compression, radio link control, and media access to obtain a service bit stream. It should be noted that packet data aggregation is the first step in processing service data packets, executed by the Service Data Adaptation Protocol (SDAP) layer of the primary satellite. This operation mainly involves classifying, labeling, and mapping service data packets of different QoS (Quality of Service) streams, enabling the service data packets to adapt to subsequent transmission protocols and channels, and ensuring that service data of different priorities and types can be transmitted according to preset quality of service requirements.

[0070] Packet data compression is a processing operation performed by the Packet Data Convergence Protocol (PDCP) layer of the main satellite during packet data aggregation. This operation uses a specific compression algorithm to compress the header information of the service data packets after packet data aggregation, reducing the overall size of the data packets and thus reducing bandwidth consumption during data transmission and improving transmission efficiency. Simultaneously, this operation also encrypts and protects the integrity of the data packets, ensuring the security of service data during transmission and preventing data theft or tampering.

[0071] Radio Link Control (RLC) is a processing operation performed by the Radio Link Control (RLC) layer of the primary satellite, primarily handling compressed service data. This operation includes data segmentation, concatenation, and retransmission control. When the length of the service data exceeds the maximum length that the physical layer channel can carry, the RLC layer segments the data into appropriate lengths. If the data length is too short, multiple short data segments are concatenated into a single, compliant data unit. Simultaneously, if a subsequent data transmission failure is detected, the RLC layer initiates a retransmission mechanism to ensure reliable transmission of the service data to the next layer.

[0072] Media access processing is a processing operation performed by the Medium Access Control (MAC) layer of the primary satellite. It involves processing service data packets before they enter the physical layer in the user plane protocol stack. Its main responsibilities include scheduling, priority management, and logical channel multiplexing of data units from the RLC layer.

[0073] The service bitstream is a binary data stream obtained after service data packets have undergone packet aggregation, packet compression, radio link control, and media access processing. This bitstream has completed a series of processes such as format adaptation, compression, encryption, segmentation, and multiplexing, and meets the transmission requirements of the physical layer.

[0074] Understandably, the primary satellite receives service data packets transmitted from the core network, confirms their integrity, and then transmits them to the SDAP layer. The SDAP layer performs packet data aggregation processing on the service data packets, classifying, marking, and mapping the packets according to QoS requirements. After processing, the packets are transmitted to the PDCP layer. The PDCP layer performs packet data compression processing on the received data packets, reducing the packet size through header compression algorithms while performing encryption and integrity protection. After processing, the packets are transmitted to the RLC layer. The RLC layer performs radio link control processing on the data packets, segmenting or concatenating the data according to the physical layer channel capacity. If retransmission is required later, it records this. After processing, the data units are transmitted to the MAC layer. The MAC layer performs media access processing on the data units, performing resource scheduling, priority management, and logical channel multiplexing. It multiplexes data from multiple logical channels into a single physical channel data unit, outputting the service bitstream.

[0075] Step S32: Input the service bit stream into the physical downlink shared channel of the physical layer to obtain the initial service waveform; It should be noted that the Physical Downlink Shared Channel (PDSCH) is a channel in the physical layer used to transmit service data to terminals, and it is the key carrier for transmitting service data from the primary satellite to the terminal. This channel has a shared characteristic, allowing simultaneous transmission of service data to multiple terminals. The primary satellite achieves efficient transmission of service data through resource allocation and scheduling of this channel. In cooperative transmission scenarios, both the primary and secondary satellites send service-related signals to the terminal through their respective PDSCHs, forming the main transmission path for service data to reach the terminal. The initial service waveform is the signal waveform formed after the service bitstream is input into the physical layer's PDSCH and undergoes preliminary processing by the physical layer.

[0076] Understandably, the service bitstream is transmitted from the MAC layer to the physical layer. After receiving the service bitstream, the physical layer performs channel coding and interleaving. Channel coding increases data redundancy, improving the data's ability to resist interference and fading during transmission. Interleaving disperses consecutive errors, facilitating subsequent error correction. The physical layer maps the channel-coded and interleaved service bitstream onto the time-frequency resource block of the physical downlink shared channel, determining the transmission location of the service data in the physical downlink shared channel. The physical layer uses orthogonal frequency division multiplexing modulation to modulate the mapped service bitstream, converting the digital service bitstream into an analog signal waveform. Only a cyclic prefix (CP) is added to the modulated signal waveform to eliminate inter-symbol interference and inter-carrier interference, forming the initial service waveform, thus completing the conversion from the service bitstream to the initial service waveform.

[0077] Step S33: Switch the current waveform modulation mode from orthogonal frequency division multiplexing to the target modulation mode; In this embodiment, when cooperative transmission is initiated, the Physical Downlink Shared Channel (PDSCH) carrying service data switches the waveform modulation mode from Orthogonal Frequency Division Multiplexing (OFDM) to Orthogonal Time-Frequency Controlled Mode (OTFS) or Analog Radio Frequency Division Multiplexing (AFDM) to overcome the dual-selection characteristics of distributed satellite channels.

[0078] Understandably, the physical layer of the primary satellite monitors the current transmission scenario in real time. When it confirms that a multi-satellite collaborative transmission scenario has been entered, and the initially adopted orthogonal frequency division multiplexing (OFDM) modulation method cannot meet the requirements for combating time-varying rapid fading, it triggers a waveform modulation method switching process. Based on the current channel conditions, service data type, and transmission requirements, the physical layer of the primary satellite selects a suitable modulation method from two modulation methods: orthogonal time-frequency modulation and pseudo-RF multiplexing. If time-varying rapid fading is severe in the channel and the service has extremely high requirements for transmission stability, orthogonal time-frequency modulation can be prioritized. If the channel conditions are relatively mild and the requirements for transmission efficiency are high, pseudo-RF multiplexing can be selected. The physical layer of the primary satellite configures the modulation parameters corresponding to the target modulation method, including the time-frequency resource grid structure, subcarrier spacing, symbol length, etc., to ensure that the modulation parameters match the target modulation method. The physical layer of the primary satellite completes the switching of the modulation module, officially switching the current waveform modulation method from orthogonal frequency division multiplexing to the selected target modulation method, preparing the modulation method for the subsequent conversion of the initial service waveform into the target service waveform.

[0079] Step S34: Convert the initial service waveform into the target service waveform according to the target modulation method.

[0080] Understandably, if the target modulation method is orthogonal time-frequency control, the orthogonal time-frequency control module of the physical layer will transform the initial service waveform from the time-frequency domain to the time-frequency domain, perform resource mapping and pulse shaping processing on the signal in the time-frequency domain, and utilize the time-frequency two-dimensional interleaving characteristics of orthogonal time-frequency control to enhance the signal's ability to resist time-varying rapid fading, thus forming the target service waveform corresponding to orthogonal time-frequency control. If the target modulation method is affine radio frequency division multiplexing, the affine radio frequency division multiplexing module of the physical layer will use affine transformation to divide and adjust the frequency of the initial service waveform, improve the spectrum utilization through a specific frequency multiplexing method, and at the same time enhance the signal's anti-interference and anti-fading capabilities, thus forming the target service waveform corresponding to affine radio frequency division multiplexing.

[0081] Step S40: Perform compensation processing on the target service waveform to obtain a time-frequency compensation signal and a multi-channel waveform signal; It should be noted that the compensation process addresses potential delay and frequency offset issues in the target service waveform during transmission. This includes downlink timing advance adjustment and Doppler frequency offset pre-compensation. It ensures that the delay difference between signals from multiple satellites reaching the mobile terminal is controlled within the cyclic prefix, and that the signal frequency offset is within acceptable limits. The time-frequency compensated signal is the signal obtained after time-frequency pre-compensation processing of the target service waveform, effectively eliminating the effects of potential delay and frequency offset during signal transmission.

[0082] Multi-channel waveform signals are obtained by copying the target service waveform multiple times according to the number of satellites in the cooperative satellite cluster, and then compensating each copied signal. Each signal corresponds to one satellite, including the primary satellite and cooperative auxiliary satellites. By transmitting multiple waveform signals from multiple satellites, the average signal-to-noise ratio of the received signal at the mobile terminal can be improved, thus enhancing transmission performance.

[0083] Understandably, after the compensation process is completed, time-frequency compensation signals and multiple waveform signals are obtained, which prepares for the subsequent transmission of signals to the mobile terminal and the cooperative auxiliary satellite.

[0084] In one feasible implementation, step S40 may include steps S41 to S44: Step S41: Perform time-frequency pre-compensation processing on the target service waveform to obtain a time-frequency compensated signal; It should be noted that time-frequency pre-compensation processing is an adjustment operation performed on the target service waveform by the Time-Frequency Pre-Compensation (TFPC) module of the main satellite's physical layer. Its core function is to eliminate potential time delay and frequency deviations that may occur during signal transmission between the satellite and the ground. This processing requires combining the ephemeris information of cooperating satellites with the terminal's positioning information to calculate and determine compensation parameters, ensuring that the signal meets the time delay and frequency requirements of multi-satellite collaborative transmission when it reaches the terminal.

[0085] The time-frequency compensation signal is the signal obtained after the target service waveform has undergone time-frequency pre-compensation processing. This signal has completed downlink timing advance adjustment and Doppler frequency offset pre-compensation, which can effectively offset the time delay caused by distance and the frequency offset caused by relative motion during signal transmission from the host satellite to the terminal.

[0086] Understandably, the real-time orbital positions of each satellite are calculated based on ephemeris information. Combined with terminal positioning information, the air interface propagation delay from the primary satellite to the terminal and the Doppler frequency offset caused by the relative motion between the primary satellite and the terminal are calculated respectively. The time-frequency pre-compensation module determines the downlink timing advance based on the calculated air interface propagation delay, and adjusts the target service waveform in advance to ensure that the signal is transmitted to the terminal in accordance with the preset time requirements. At the same time, the frequency offset compensation amount is determined based on the Doppler frequency offset value, and the frequency of the target service waveform is adjusted to compensate for the frequency offset caused by relative motion. After completing the time and frequency adjustment, a time-frequency compensated signal is obtained, which is ready for stable transmission in the satellite-to-ground link.

[0087] Step S42: Determine the cooperative satellite cluster based on the cooperative auxiliary stars, and determine the number of satellites based on the cooperative satellite cluster; It should be noted that a collaborative satellite cluster is a group of satellites consisting of a primary satellite and all selected auxiliary satellites, employing a master-slave configuration. The primary satellite plays a coordinating role within the cluster, responsible for processing service data, generating compensation signals, and signaling interaction with the core network and terminals. The auxiliary satellites play a supporting transmission role, solely responsible for receiving and forwarding signals sent by the primary satellite. Together, they provide multi-satellite transmission services to terminals and are the core execution unit for multi-satellite collaborative transmission. The number of satellites refers to the total number of auxiliary satellites included in the collaborative satellite cluster.

[0088] Understandably, the primary satellite, having already identified its cooperating auxiliary satellites, will group itself and all the selected auxiliary satellites into a single entity, forming a master-slave cooperating satellite cluster. This clarifies the primary satellite's overall coordination responsibilities and the auxiliary satellites' responsibilities for assisting in transmission. The primary satellite will then count each satellite within the cooperating satellite cluster to confirm that the cluster contains one primary satellite and several cooperating auxiliary satellites, and finally count the number of auxiliary satellites.

[0089] Step S43: Copy the target service waveform into multiple signals of the specified number of satellites; It is understandable that the waveform signal is copied P times (each copy corresponds to one cooperating satellite), and downlink timing advance (DTA) adjustment and Doppler frequency offset pre-compensation are performed on each cooperating satellite waveform signal to ensure that the time delay difference of each cooperating satellite signal arriving at the terminal is controlled within CP, and the residual frequency offset of each cooperating satellite waveform signal is controlled within a fractional multiple of the subcarrier interval.

[0090] Step S44: Perform downlink timing advance adjustment and Doppler frequency offset pre-compensation on the multiple signals to obtain multiple waveform signals, wherein the time delay difference of the multiple waveform signals is controlled within the cyclic prefix.

[0091] It should be noted that downlink timing advance adjustment is an operation that adjusts the signal transmission time of the corresponding satellite among multiple signals in advance based on the air interface propagation delay between the satellite and the terminal. Since the distance between different satellites and the terminal varies, the signal transmission delays are different. This adjustment ensures that each signal, after being transmitted from its corresponding satellite, arrives at the terminal at the same time, avoiding signal superposition and confusion caused by delay differences. It is one of the key operations to ensure multi-satellite signal synchronization.

[0092] Doppler frequency offset pre-compensation is an operation that adjusts the signal frequency of the corresponding satellite in multiple signals based on the relative motion velocity between the satellite and the terminal to compensate for the Doppler frequency offset generated during signal transmission. The relative motion between the satellite and the terminal will cause the signal frequency to shift. If no compensation is performed, the signal frequency received by the terminal will deviate from the preset value, affecting the demodulation accuracy.

[0093] Additionally, the cyclic prefix (CP) is a guard interval added before each symbol during signal modulation. Its main function is to eliminate inter-symbol interference and inter-carrier interference. In multi-satellite cooperative transmission, controlling the time delay difference of multiple waveform signals within the cyclic prefix ensures that inter-symbol interference will not occur due to time delay differences when each signal arrives at the terminal, guaranteeing accurate signal reception and superposition.

[0094] Understandably, the time-frequency pre-compensation module of the main satellite calculates the air interface propagation delay and Doppler frequency offset between each satellite and the terminal based on the ephemeris information of each satellite in the cooperative satellite cluster and the terminal's positioning information. Then, for the signal corresponding to each satellite in the multi-channel signal, it determines the downlink timing advance based on the air interface propagation delay to adjust the transmission time and ensure that the signal arrives at the terminal on time. At the same time, it determines the frequency offset compensation amount based on the Doppler frequency offset to adjust the signal frequency and offset the frequency shift caused by relative motion. After all multi-channel signals are adjusted, the time-frequency pre-compensation module performs delay detection on each signal, calculates the delay difference between any two signals arriving at the terminal, and if it exceeds the cyclic prefix range, it readjusts the downlink timing advance until the delay difference is controlled within the cyclic prefix. Finally, it obtains a multi-channel waveform signal, each corresponding to one satellite, that can be transmitted to the terminal by the corresponding satellite.

[0095] Step S50: The multi-channel waveform signals are sent to the mobile terminal, and the time-frequency compensation signal is sent to the cooperative auxiliary satellite according to the cooperative session, so that the mobile terminal can obtain service data based on the multi-channel waveform signals and the time-frequency compensation signal, and complete the cooperative transmission of the low-orbit satellite network. The service data is obtained by the cooperative auxiliary satellite forwarding the time-frequency compensation signal to the mobile terminal according to the cooperative session, and the mobile terminal parsing the multi-channel waveform signals and the time-frequency compensation signal.

[0096] Business data is the valid data that the mobile device ultimately needs to obtain. This data comes from business data packets, which are obtained after coordinated transmission by the primary satellite and auxiliary satellites and parsing processing by the mobile device.

[0097] The primary satellite transmits multiple waveform signals to the mobile terminal via the physical downlink shared channel (PLS-SMS). Simultaneously, based on the established cooperative session, it sends time-frequency compensation signals to the cooperating secondary satellite via the inter-satellite link. The secondary satellite, according to the cooperative session agreement, forwards the time-frequency compensation signals to the mobile terminal via its own PLS-SMS. During this process, the primary satellite also sends downlink control information to the mobile terminal via the physical downlink control channel, containing the location of the PLS-SMS time-frequency resources and the waveform modulation scheme. Upon receiving the signals and information, the mobile terminal first parses the downlink control information to determine the location of the PLS-SMS time-frequency resources and the waveform demodulation scheme. Then, it locates and demodulates the corresponding signal, and finally extracts the service data through protocol-layer parsing, completing the low-Earth orbit satellite network cooperative transmission and meeting its own service requirements.

[0098] In one feasible implementation, "sending the multi-channel waveform signal to the mobile terminal" in step S50 may include steps S51 to S54: Step S51: Obtain the preset field format, preset set level, and current downlink control information format of the current physical downlink control channel; It should be noted that the preset field format is predefined and serves as a structural specification for adding specific functional fields to the downlink control information format. In this embodiment, the format specifies the exact location, number of bits, and encoding rules for the "waveform modulation method" field to be added to the downlink control information format. The "waveform modulation method" field occupies 2 bits and is fixed at the end of downlink control information format 1_1. It is used to indicate to the mobile terminal the waveform demodulation method of the physical downlink shared channel (such as orthogonal time-frequency modulation or simulated radio frequency division multiplexing). This format is the fundamental standard to ensure that the newly added field can be correctly added by the main satellite and accurately parsed by the mobile terminal.

[0099] The preset aggregation level (AL) is a pre-defined standard for the degree of resource aggregation when the physical downlink control channel carries downlink control information. In this embodiment, the preset aggregation level is configured as 16, meaning that the physical downlink control channel aggregates 16 resource element groups (REGs) into one resource unit to transmit downlink control information.

[0100] The current physical downlink control channel's initial downlink control information format does not include a waveform modulation scheme field, and its ensemble level may not be adapted to the requirements of multi-satellite collaborative transmission. This channel is a crucial carrier for transmitting control signaling between the primary satellite and the mobile terminal, primarily used to transmit control information such as resource allocation and modulation / coding schemes of the physical downlink shared channel to the mobile terminal. Its performance directly affects the mobile terminal's efficiency in receiving and demodulating service signals. The current downlink control information format is the structural form used by the current physical downlink control channel to organize and carry downlink control information.

[0101] Step S52: Update the current downlink control information format according to the preset field format to obtain the target downlink control information format; It should be noted that the target downlink control information format is obtained by updating the current downlink control information format according to the preset field format, and is a downlink control information structure adapted to the requirements of multi-satellite collaborative transmission. In this embodiment, the target downlink control information format is formed by adding a waveform modulation mode field of 2 bits at the end on the basis of the original downlink control information format 1_1. It can transmit the waveform demodulation mode information of the physical downlink shared channel to the mobile terminal, which solves the problem that the original format cannot support waveform switching indication in multi-satellite collaborative transmission. It is the core structure for the main satellite to transmit key control information to the mobile terminal.

[0102] Understandably, according to the requirements of the preset field format, a waveform modulation mode field is added to the end of the current downlink control information format 1_1. This field occupies 2 bits, and the encoding rules are agreed upon in advance, such as 01 representing orthogonal time-frequency modulation and 10 representing simulated radio frequency multiplexing. The control information processing module performs integrity and compatibility checks on the updated downlink control information format to confirm that the added field does not damage the structure and function of the original field, and that the overall format meets the transmission requirements of the physical downlink control channel. After the check is completed, the target downlink control information format is obtained.

[0103] Step S53: Update the current physical downlink control channel according to the preset set level and the target downlink control information format to obtain the target physical downlink control channel; It should be noted that the target physical downlink control channel is a control signaling transmission channel adapted to the requirements of multi-satellite collaborative transmission, obtained by updating the current physical downlink control channel according to a preset set level and target downlink control information format. This channel uses a preset set level 16 to transmit the target downlink control information format and is transmitted only by the primary satellite. It can stably transmit downlink control information containing waveform modulation scheme fields to the mobile terminal, solving the problems of insufficient reliability and incomplete control information of the current physical downlink control channel. It is the core carrier for transmitting key control commands from the primary satellite to the mobile terminal in multi-satellite collaborative transmission.

[0104] Understandably, in accordance with the preset set level 16 requirement, the resource aggregation method of the current physical downlink control channel is adjusted, and the resource elements of the channel are aggregated into groups of 16 to form new resource transmission units, thereby improving the anti-interference capability and reception reliability of the channel signal; the target downlink control information format is set to the default control information format of the current physical downlink control channel to ensure that all downlink control information transmitted by the channel in the future includes the waveform modulation method field; the channel configuration module will also adjust the time and frequency resource position of the physical downlink control channel to ensure that it does not overlap with the time and frequency resources of the physical downlink shared channel and avoid signal interference.

[0105] Step S54: The multi-channel waveform signals are transmitted to the mobile terminal through the target physical downlink control channel.

[0106] After acquiring multiple waveform signals and the target physical downlink control channel, the primary satellite signal transmission module integrates the primary satellite signal from the multiple waveform signals with the target downlink control information carried by the target physical downlink control channel in terms of time and frequency resources, ensuring that both are transmitted in the same time slot and that resources do not overlap. The primary satellite transmission unit converts the integrated signal into a radio frequency signal and transmits it to the mobile terminal's service beam, while monitoring the transmission status of the target physical downlink control channel in real time to prevent signal interruption or severe interference. After receiving the primary satellite signal, the mobile terminal receiving unit acquires the target downlink control information through the target physical downlink control channel, receives the primary satellite signal from the multiple waveform signals, and waits for other signals relayed by the cooperating auxiliary satellite to complete subsequent analysis.

[0107] After receiving the signal from the cooperating satellite cluster, the mobile terminal first performs blind detection of the PDCCH to parse the DCI Format 1_1, obtains the waveform tuning mode (OTFS) of the current PDSCH, and then performs OTFS demodulation according to the PDSCH time-frequency resource block indicated by the DCI, parsing out the service data layer by layer. (Refer to...) Figure 6 , Figure 6 This is a schematic diagram of the downlink control information waveform modulation scheme in the first embodiment of the cooperative transmission method for low-Earth orbit satellite networks according to this application. Figure 6As shown, the structure of Downlink Control Information Format 1_1 (DCI Format 1_1) consists of two parts: the original downlink control information bits (DCI original bits) and the newly added field, waveform modulation mode. The DCI original bits are the original control information bits, while the newly added field is a 2-bit field indicating the waveform modulation mode. The three possible values ​​for the newly added field are: 00 for Orthogonal Frequency Division Multiplexing (OFDM), 01 for Orthogonal Time-Frequency Spatial Modulation (OTFS), and 10 for Analogous Radio Frequency Division Multiplexing (AFDM). These waveform modulation modes guide the User Equipment (UE) on how to demodulate the received signal. Appropriate modulation schemes can be selected according to different communication conditions and requirements to improve communication efficiency and signal quality.

[0108] Reference Figure 7 , Figure 7 This is a schematic diagram of the time-frequency arrangement of the physical downlink control channel and the physical downlink shared channel in the multi-satellite cooperative transmission mode of the first embodiment of the cooperative transmission method for low-Earth orbit satellite networks of this application.

[0109] like Figure 7 As shown in the figure, the horizontal axis represents time, and the vertical axis represents frequency. One OFDM symbol occupies a certain amount of time and frequency resources. Different filling shapes are used to represent different channels and resource elements: the diagonally filled area represents the PDCCH (OFDM waveform), which is used to transmit control information and is scheduled to be the same as the PDSCH in the same time slot unit. The horizontally filled area represents the PDSCH (OTFS waveform), which is used to transmit user data and employs Orthogonal Time-Frequency Spatial Modulation (OTFS) technology to improve performance in high-speed mobile environments. Blank areas represent filled zero resource elements (REs), which are not used for data transmission but are used for flexible scheduling and can be allocated to the PDCCH or PDSCH as needed. The figure also labels the time slot unit, which is the basic time unit used for resource scheduling in the 5G system. The scheduling of the PDCCH with the PDSCH in the same time slot unit means that control information and user data are closely related in time, which helps improve scheduling efficiency and accuracy. In this way, the system can flexibly allocate and adjust the resources of PDCCH and PDSCH according to actual communication needs and environmental conditions to optimize overall communication performance.

[0110] This embodiment provides a collaborative transmission method for low-Earth orbit (LEO) satellite networks. By implementing multi-satellite collaborative transmission in LEO networks, it solves the technical problem of unstable high-speed and high-bandwidth downlink transmission in scenarios where mobile phones are directly connected to LEO satellites. Through the collaborative work of the primary satellite and cooperating auxiliary satellites, not only is the downlink transmission performance of handheld terminals enhanced, but the deployment cost of multi-satellite collaborative systems is also significantly reduced, facilitating the commercialization of multi-satellite collaborative transmission technology and achieving beneficial effects such as improved communication efficiency, enhanced signal coverage, and improved signal quality and reliability.

[0111] Based on the first embodiment of this application, in the second embodiment of this application, the content that is the same as or similar to that in the first embodiment described above can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 8 The cooperative transmission method of the low-Earth orbit satellite network described in step S50 further includes steps S60-S80: Step S60: Upon receiving the service data reception completion signal sent by the mobile terminal, a session release command is sent to the cooperative auxiliary star through the cooperative session, so that the cooperative auxiliary star stops forwarding the time-frequency compensation signal according to the session release command, releases the service beam resources allocated for cooperative transmission, and sends back a release completion signal. It should be noted that the service data reception completion signal is an acknowledgment message sent by the mobile terminal to the main satellite after successfully parsing all multi-channel waveform signals and time-frequency compensation signals to obtain complete service data. This signal contains information such as the mobile terminal identifier and the session number of this collaborative transmission, and is used to inform the main satellite that the current service transmission has been completed and there is no need to continue sending or forwarding service-related signals. It is a key trigger signal for initiating the collaborative transmission release process, ensuring that the resource release operation is only performed after the service is completed.

[0112] The session release command is a control command sent by the primary satellite to the secondary satellite via the collaborative session after receiving the service data reception completion signal. The command contains information such as the session identifier and release time requirements, and explicitly requires the secondary satellite to stop its current signal forwarding operation and release the allocated resources. It serves as the direct basis for the secondary satellite to execute the resource release action, ensuring that all secondary satellites can synchronously initiate the release process.

[0113] Service beam resources are dedicated beam resources allocated by the auxiliary satellite during collaborative transmission to send service signals to mobile devices. These resources include time-frequency resources and power resources. This resource is a key hardware support for the auxiliary satellite to achieve signal forwarding. Timely release after transmission is completed avoids waste caused by prolonged resource occupation and ensures that other mobile devices or services can properly utilize this resource.

[0114] The release completion signal is a status confirmation message sent by the auxiliary satellite to the primary satellite after performing operations such as stopping the forwarding of the time-frequency compensation signal and releasing service beam resources. The message contains information such as the auxiliary satellite identifier and the type of resources released, which is used to inform the primary satellite that it has completed the resource release. This provides the primary satellite with the status basis for subsequently initiating resource reclamation requests to the core network, ensuring that the release process proceeds step by step.

[0115] Understandably, the primary satellite continuously monitors whether it receives the mobile terminal's service data reception completion signal. Upon receiving the signal, it parses the session number and mobile terminal identifier in the signal to confirm that the corresponding collaborative transmission service has been completed. Then, it locates the collaborative session based on the session number and sends a session release instruction containing the type of resources to be released and the time limit requirements to all participating collaborative auxiliary satellites through this session. After receiving the instruction, the collaborative auxiliary satellite immediately stops forwarding the time-frequency compensation signal, then initiates the service beam resource release process, releases the specially allocated time-frequency, power, and other service beam resources, updates the resource status to idle, generates a release completion signal, and feeds back to the primary satellite through the collaborative session to inform it that the resource release has been completed and awaits subsequent instructions from the primary satellite.

[0116] Step S70: Upon receiving the release completion signal, a session resource reclamation request is sent to the core network, so that the core network releases the network resources allocated for cooperative transmission according to the session resource reclamation request and sends back a resource reclamation confirmation message. It should be noted that the session resource reclamation request is a resource management request sent by the primary satellite to the core network after confirming that all cooperating auxiliary satellites have completed resource release. The request includes the PDU session identifier of this cooperative transmission and the type of network resources allocated, and is used to inform the core network that the current cooperative transmission service has ended and the network resources allocated to it need to be reclaimed.

[0117] Network resources are resources allocated by the core network to support service data transmission when collaborative transmission is initiated. These resources include dedicated bearer resources, QoS (Quality of Service) guarantee resources, and session management resources. These resources are crucial for the transmission of service data between the core network and the main satellite. Timely release of these resources can prevent waste of network resources and ensure that other terminals or services can normally apply for and use network resources.

[0118] The resource reclamation confirmation message is a status message sent by the core network to the primary satellite after all network resources have been released. The message includes information such as the session identifier and a list of reclaimed resources, informing the primary satellite's core network that all resources have been released. It provides the final basis for the primary satellite to send a cooperative transmission termination message to the mobile device, ensuring a closed-loop resource release process at the network layer.

[0119] Understandably, after receiving release completion signals from all cooperating auxiliary satellites, the primary satellite aggregates and verifies the signals to confirm that each auxiliary satellite has completed resource release, avoiding any omissions. It then generates a session resource reclamation request, clearly indicating the PDU session identifier of this cooperative transmission, the bearer number allocated by the core network, and the QoS resource type, ensuring the core network accurately identifies the resources to be reclaimed. The request is then securely and reliably sent to the core network via a dedicated signaling link that follows the communication protocol between low-Earth orbit satellite networks and the core network. Upon receiving the request, the core network searches for and releases dedicated bearer resources and QoS-guaranteed resources one by one based on the session identifier, updates the resource scheduling list, marks the released resources as available, generates a resource reclamation confirmation message, and sends it back to the primary satellite via the dedicated signaling link, informing the network-level satellite that all resources have been reclaimed.

[0120] Step S80: Upon receiving the resource reclamation confirmation message, a cooperative transmission termination message is sent to the mobile terminal so that the mobile terminal stops parsing the multi-channel waveform signal and the time-frequency compensation signal according to the cooperative transmission termination message, thereby completing the resource release of cooperative transmission.

[0121] The cooperative transmission termination message is a termination notification sent by the primary satellite to the mobile device after receiving the resource reclamation confirmation message. The message contains information such as a session termination identifier and instructions for switching back to single-satellite transmission, clearly informing the mobile device that the current cooperative transmission has completely ended and that it is necessary to stop parsing multi-channel waveform signals and time-frequency compensation signals, while also guiding the mobile device to switch back to single-satellite transmission mode.

[0122] Understandably, after receiving the resource reclamation confirmation message from the core network, the primary satellite parses the resource reclamation list and, in conjunction with the release completion signal from the cooperating auxiliary satellite, confirms that the entire link resource release is ready. Subsequently, it generates a cooperative transmission termination message containing the session number of this cooperative transmission, the termination time, and the mobile terminal's single-satellite transmission switching configuration parameters, and sends it to the mobile terminal through the target physical downlink control channel, which still maintains normal signaling transmission functionality. Upon receiving and parsing this message, the mobile terminal confirms the end of the cooperative transmission and immediately ceases demodulation and protocol layer parsing of multiple waveform signals and time-frequency compensation signals to release its own signal processing resources. Then, following the switching instructions in the message, it automatically switches back to single-satellite transmission mode to await connection with a single satellite, thus completing the full-link resource release for cooperative transmission.

[0123] This embodiment provides a cooperative transmission method for low-Earth orbit (LEO) satellite networks. By implementing a technical means to release resources allocated for multi-satellite cooperative transmission after the completion of service data reception in the LEO satellite network, it solves the technical problem of how to efficiently release the on-board and ground network resources allocated for cooperative transmission after the completion of multi-satellite cooperative transmission. This ensures timely recovery and effective utilization of resources, improves the resource utilization rate and communication efficiency of the LEO satellite network, and achieves the beneficial effect of improving the overall system performance.

[0124] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the cooperative transmission method of the low-orbit satellite network of this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0125] This application also provides a cooperative transmission device for low-Earth orbit satellite networks, please refer to... Figure 9 The cooperative transmission device for the low-Earth orbit satellite network includes: The auxiliary satellite determination module 10 is used to determine the auxiliary satellite for cooperation based on the positioning information of the mobile terminal and the ephemeris information of the low-orbit satellite network when a multi-satellite cooperative transmission request is received from the mobile terminal. The session initiation module 20 is used to initiate a collaborative session with the collaborative auxiliary satellite based on the mobile terminal information of the mobile terminal. The waveform conversion module 30 is used to switch the current waveform modulation mode from orthogonal frequency division multiplexing to orthogonal time-frequency control mode or simulated radio frequency division multiplexing when a service data packet is received, to obtain the target modulation mode, and to convert the service data packet into a target service waveform according to the target modulation mode. Signal compensation module 40 is used to perform compensation processing on the target service waveform to obtain time-frequency compensation signal and multi-channel waveform signal; The service transmission module 50 is used to send the multi-channel waveform signals to the mobile terminal and, according to the cooperative session, send the time-frequency compensation signal to the cooperative auxiliary satellite, so that the mobile terminal can obtain service data based on the multi-channel waveform signals and the time-frequency compensation signal, and complete the cooperative transmission of the low-Earth orbit satellite network. The service data is obtained by the cooperative auxiliary satellite forwarding the time-frequency compensation signal to the mobile terminal according to the cooperative session, and the mobile terminal parsing the multi-channel waveform signals and the time-frequency compensation signal.

[0126] The low-Earth orbit (LEO) satellite network collaborative transmission device provided in this application, employing the LEO satellite network collaborative transmission method described in the above embodiments, can solve the technical problem that the downlink cannot stably achieve high-speed and high-bandwidth transmission in scenarios where mobile phones are directly connected to LEO satellites. Compared with the prior art, the beneficial effects of the LEO satellite network collaborative transmission device provided in this application are the same as those of the LEO satellite network collaborative transmission method provided in the above embodiments, and other technical features in the LEO satellite network collaborative transmission device are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0127] This application provides a cooperative transmission device for a low-Earth orbit (LEO) satellite network. The LEO satellite network cooperative transmission device includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the LEO satellite network cooperative transmission method in the above embodiment 1.

[0128] The following is for reference. Figure 10 This document illustrates a structural schematic diagram of a cooperative transmission device suitable for implementing the embodiments of this application's low-Earth orbit (LEO) satellite network. The cooperative transmission device for the LEO satellite network in these embodiments may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), in-vehicle terminals (e.g., in-vehicle navigation terminals), and fixed terminals such as digital TVs and desktop computers. Figure 10 The cooperative transmission equipment for the low-Earth orbit satellite network shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0129] like Figure 10As shown, the collaborative transmission equipment for the low-Earth orbit satellite network may include a processing unit 1001 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in ROM (Read Only Memory) 1002 or a program loaded from storage device 1003 into RAM (Random Access Memory) 1004. RAM 1004 also stores various programs and data required for the operation of the collaborative transmission equipment for the low-Earth orbit satellite network. The processing unit 1001, ROM 1002, and RAM 1004 are interconnected via bus 1005. Input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to I / O interface 1006: input devices 1007 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 1008 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 1003 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1009. Communication device 1009 allows the cooperative transmission equipment of the low-Earth orbit satellite network to exchange data wirelessly or via wired communication with other devices. Although cooperative transmission equipment of a low-Earth orbit satellite network with various systems is shown in the figure, it should be understood that it is not required to implement or possess all the systems shown. More or fewer systems may be implemented or possessed alternatively.

[0130] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. The embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, containing program code for performing the methods shown in the flowcharts. This computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from ROM 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0131] The low-Earth orbit (LEO) satellite network collaborative transmission device provided in this application, employing the LEO satellite network collaborative transmission method described in the above embodiments, can solve the technical problem that the downlink cannot stably achieve high-speed and high-bandwidth transmission in scenarios where mobile phones are directly connected to LEO satellites. Compared with the prior art, the beneficial effects of the LEO satellite network collaborative transmission device provided in this application are the same as those of the LEO satellite network collaborative transmission method provided in the above embodiments, and other technical features in this LEO satellite network collaborative transmission device are the same as those disclosed in the previous embodiment method, and will not be repeated here.

[0132] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples. The above descriptions are merely specific embodiments of this application, and the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. The scope of protection of this application should be determined by the scope of the claims.

[0133] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, the computer-readable program instructions being used to execute the cooperative transmission method of the low-Earth orbit satellite network in the above embodiments.

[0134] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or any combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, system, or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium.

[0135] The aforementioned computer-readable storage medium may be included in the cooperative transmission equipment of the low-Earth orbit satellite network; or it may exist independently and not be assembled into the cooperative transmission equipment of the low-Earth orbit satellite network.

[0136] The aforementioned computer-readable storage medium carries one or more programs. When these programs are executed by the cooperative transmission equipment of the low-Earth orbit (LEO) satellite network, the cooperative transmission equipment of the LEO satellite network: upon receiving a multi-satellite cooperative transmission request from a mobile terminal, determines a cooperative auxiliary satellite based on the mobile terminal's positioning information and the LEO satellite network's ephemeris information; initiates a cooperative session with the cooperative auxiliary satellite based on the mobile terminal's information; switches the current waveform modulation mode from orthogonal frequency division multiplexing (OFDM) to the target modulation mode; converts the service data packets into a target service waveform based on the target modulation mode; performs compensation processing on the target service waveform to obtain a time-frequency compensation signal and multiple waveform signals; sends the multiple waveform signals to the mobile terminal; and sends the time-frequency compensation signal to the cooperative auxiliary satellite based on the cooperative session, enabling the mobile terminal to obtain service data based on the multiple waveform signals and the time-frequency compensation signal, thus completing the cooperative transmission of the LEO satellite network.

[0137] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​and conventional procedural programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including LAN (Local Area Network) or WAN (Wide Area Network)—or can be connected to an external computer.

[0138] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0139] The modules involved in the embodiments of this application can be implemented in software or hardware. The name of a module does not necessarily limit the functionality of that module.

[0140] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the aforementioned cooperative transmission method for low-Earth orbit satellite networks. This solves the technical problem that the downlink cannot stably achieve high-speed and high-bandwidth transmission in scenarios where mobile phones are directly connected to low-Earth orbit satellites. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the cooperative transmission method for low-Earth orbit satellite networks provided in the above embodiments, and will not be elaborated upon here.

[0141] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the cooperative transmission method for low-Earth orbit satellite networks as described above.

[0142] The computer program product provided in this application can solve the technical problem that the downlink cannot stably achieve high-speed and high-bandwidth transmission in scenarios where mobile phones are directly connected to low-Earth orbit satellites. Compared with the prior art, the beneficial effects of the computer program product provided in this application are the same as the beneficial effects of the cooperative transmission method for low-Earth orbit satellite networks provided in the above embodiments, and will not be repeated here.

[0143] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A cooperative transmission method for low-Earth orbit satellite networks, characterized in that, The method includes: Upon receiving a multi-satellite collaborative transmission request from a mobile terminal, the auxiliary satellites for collaboration are determined based on the mobile terminal's positioning information and the ephemeris information of the low-Earth orbit satellite network. A collaborative session with the auxiliary satellite is initiated based on the mobile terminal information of the mobile terminal. Upon receiving a service data packet, the current waveform modulation mode is switched from orthogonal frequency division multiplexing to the target modulation mode, and the service data packet is converted into a target service waveform according to the target modulation mode. The target modulation mode includes orthogonal time-frequency control or simulated radio frequency division multiplexing. The target service waveform is compensated to obtain a time-frequency compensated signal and a multi-channel waveform signal; The multi-channel waveform signals are sent to the mobile terminal, and the time-frequency compensation signal is sent to the cooperative auxiliary satellite according to the cooperative session, so that the mobile terminal can obtain service data based on the multi-channel waveform signals and the time-frequency compensation signal, and complete the cooperative transmission of the low-Earth orbit satellite network. The service data is obtained by the cooperative auxiliary satellite forwarding the time-frequency compensation signal to the mobile terminal according to the cooperative session, and the mobile terminal parsing the multi-channel waveform signals and the time-frequency compensation signal.

2. The method as described in claim 1, characterized in that, The step of initiating a collaborative session with the auxiliary satellite based on the mobile terminal information includes: The identification information and location information are determined based on the mobile terminal information. The identification information and the positioning information are sent to the cooperative auxiliary satellite so that the cooperative auxiliary satellite aligns the service beam center with the mobile terminal according to the identification information and the positioning information, and feeds back the virtual radio resource control connection established with the mobile terminal. Upon receiving the virtual radio resource control connection, a multi-satellite cooperative transmission permission message is sent to the mobile terminal, so that the mobile terminal responds with a session establishment request message based on the multi-satellite cooperative transmission permission message; The session establishment request message is sent to the core network so that the core network establishes and sends back a session reception message based on the session establishment request message. Upon receiving the session reception message, a collaborative session with the cooperative auxiliary satellite is initiated.

3. The method as described in claim 1, characterized in that, The step of switching the current waveform modulation mode from orthogonal frequency division multiplexing to the target modulation mode when a service data packet is received, and converting the service data packet into a target service waveform according to the target modulation mode, includes: Upon receiving a service data packet, the service data packet is sequentially processed through packet data aggregation, packet data compression, radio link control, and media access to obtain a service bit stream; The service bitstream is input into the physical downlink shared channel of the physical layer to obtain the initial service waveform; Switch the current waveform modulation mode from orthogonal frequency division multiplexing to the target modulation mode; The initial service waveform is converted into the target service waveform according to the target modulation method.

4. The method as described in claim 1, characterized in that, The step of compensating the target service waveform to obtain a time-frequency compensated signal and a multi-channel waveform signal includes: Perform time-frequency pre-compensation processing on the target service waveform to obtain a time-frequency compensated signal; The cooperative satellite cluster is determined based on the cooperative auxiliary stars, and the number of satellites is determined based on the cooperative satellite cluster; The target service waveform is copied into multiple signals for the specified number of satellites; Downlink timing advance adjustment and Doppler frequency offset pre-compensation are performed on the multiple signals to obtain multiple waveform signals, wherein the time delay difference of the multiple waveform signals is controlled within the cyclic prefix.

5. The method as described in claim 1, characterized in that, The step of sending the multi-channel waveform signals to the mobile terminal includes: Obtain the preset field format, preset set level, and current downlink control information format of the current physical downlink control channel; The current downlink control information format is updated according to the preset field format to obtain the target downlink control information format; The current physical downlink control channel is updated according to the preset set level and the target downlink control information format to obtain the target physical downlink control channel; The multi-channel waveform signals are transmitted to the mobile terminal through the target physical downlink control channel.

6. The method as described in claim 1, characterized in that, The step of determining the cooperating auxiliary satellites based on the mobile terminal's positioning information and the ephemeris information of the low-Earth orbit satellite network upon receiving a multi-satellite cooperative transmission request from the mobile terminal includes: When a multi-satellite collaborative transmission request is received from a mobile terminal, the ephemeris information, preset distance threshold, and preset elevation angle threshold of the low-orbit satellites are obtained. The ephemeris information includes the real-time orbital position, communication payload status, and inter-satellite link bandwidth of each low-orbit satellite. Based on the location information of the mobile terminal and the real-time orbit position, calculate the satellite-to-ground link distance and communication angle between the low-orbit satellite and the mobile terminal; A candidate satellite list is formed by filtering low-Earth orbit satellites whose satellite-to-ground link distance is less than the preset distance threshold, whose communication angle is greater than the preset elevation angle threshold, and whose communication payload has idle resources. Cooperative auxiliary satellites are determined from the candidate satellite list based on the inter-satellite link bandwidth.

7. The method as described in claim 1, characterized in that, After the steps of sending the multi-channel waveform signals to the mobile terminal and sending the time-frequency compensation signal to the cooperative auxiliary satellite according to the cooperative session, so that the mobile terminal can obtain service data based on the multi-channel waveform signals and the time-frequency compensation signal to complete the cooperative transmission of the low-Earth orbit satellite network, the method further includes: Upon receiving the service data reception completion signal sent by the mobile terminal, a session release command is sent to the cooperative auxiliary star through the cooperative session, so that the cooperative auxiliary star stops forwarding the time-frequency compensation signal according to the session release command, releases the service beam resources allocated for cooperative transmission, and sends back a release completion signal. Upon receiving the release completion signal, a session resource reclamation request is sent to the core network, so that the core network releases the network resources allocated for cooperative transmission according to the session resource reclamation request and sends back a resource reclamation confirmation message. Upon receiving the resource reclamation confirmation message, a collaborative transmission termination message is sent to the mobile terminal, so that the mobile terminal stops parsing the multi-channel waveform signal and the time-frequency compensation signal according to the collaborative transmission termination message, thereby completing the resource release of collaborative transmission.

8. A cooperative transmission device for a low-Earth orbit satellite network, characterized in that, The device includes: The auxiliary satellite determination module is used to determine the auxiliary satellite for cooperation based on the positioning information of the mobile terminal and the ephemeris information of the low-Earth orbit satellite network when a multi-satellite cooperative transmission request is received from the mobile terminal. The session initiation module is used to initiate a collaborative session with the collaborative auxiliary satellite based on the mobile terminal information of the mobile terminal. The waveform conversion module is used to switch the current waveform modulation mode from orthogonal frequency division multiplexing to orthogonal time-frequency control or simulated radio frequency division multiplexing when a service data packet is received, to obtain the target modulation mode, and to convert the service data packet into a target service waveform according to the target modulation mode; The signal compensation module is used to perform compensation processing on the target service waveform to obtain a time-frequency compensated signal and a multi-channel waveform signal; The service transmission module is used to send the multi-channel waveform signals to the mobile terminal and, according to the cooperative session, send the time-frequency compensation signal to the cooperative auxiliary satellite, so that the mobile terminal can obtain service data based on the multi-channel waveform signals and the time-frequency compensation signal, and complete the cooperative transmission of the low-Earth orbit satellite network. The service data is obtained by the cooperative auxiliary satellite forwarding the time-frequency compensation signal to the mobile terminal according to the cooperative session, and the mobile terminal parsing the multi-channel waveform signals and the time-frequency compensation signal.

9. A collaborative transmission device for a low-Earth orbit satellite network, characterized in that, The device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the cooperative transmission method for a low-Earth orbit satellite network as described in any one of claims 1 to 7.

10. A storage medium, characterized in that, The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, it implements the steps of the cooperative transmission method for a low-Earth orbit satellite network as described in any one of claims 1 to 7.

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