Communication methods, communication devices, and communication systems

Abstract

A communication method, a communication device, and a communication system are provided and are applicable to the field of communication technology. The method comprises the step of a first satellite transmitting a first broadcast message and, in response, a terminal device receiving the first broadcast message, wherein the first broadcast message includes first display information, and the first display information represents ephemeris information of a second satellite. The terminal device receives a second broadcast message from the second satellite based on the first display information. According to an embodiment of the present application, the time required for the terminal device to capture the satellite can be reduced.

Description

Technology Field

[0001] This application was filed with the National Intellectual Property Administration of China on January 15, 2024, and claims priority to Chinese patent application No. 202410054547.3, titled "communication method, communication device, and communication system," the full text of which is incorporated herein by reference.

[0002] The present application relates to the field of communication technology, and in particular, to communication methods, communication devices, and communication systems. Background Technology

[0003] In a non-terrestrial network (NTN) system, a satellite may transmit synchronization signal blocks (SSBs) using a beam sweeping method. To access the satellite, a terminal device needs to scan multiple SSBs transmitted by the satellite across multiple frequencies and beam directions. For a single frequency, the terminal device needs to scan the SSBs transmitted by the satellite across beam directions, and the time required for the terminal device to scan a single frequency is determined by the SSB sweeping periodicity and the number of beams required for the terminal device to complete the scanning. If the terminal device needs to scan multiple frequencies, the time required for the terminal device to acquire the satellite is directly proportional to the number of frequencies to be scanned.

[0004] However, in the aforementioned method for accessing a satellite by a terminal device, it takes a long time for the terminal device to acquire the satellite.

[0005] Embodiments of the present application provide a communication method, a communication device, and a communication system, thereby reducing the satellite acquisition time for a terminal device.

[0006] According to a first aspect, an embodiment of the present application provides a communication method applied to a terminal device. It may be understood that the terminal device may include a terminal device or a chip (system) or a circuit used in the terminal device. This is not limited in the present application. The method comprises

[0007] The step of receiving a first broadcast message from a first satellite, wherein the first broadcast message includes first display information, and the first display information represents ephemeris information of a second satellite; and the step of receiving a second broadcast message from a second satellite based on the first display information.

[0008] In the embodiments of the present application, the coverage range of the first satellite is greater than the coverage range of the second satellite. Alternatively, the orbital altitude of the first satellite is higher than the orbital altitude of the second satellite. The first satellite may be a high-orbit satellite, and the second satellite may be a low-orbit satellite. The second satellite may be located within the coverage range of the first satellite. The first satellite may broadcast the ephemeris information of the second satellite, so that the terminal device can acquire the ephemeris information of the second satellite and adjust the direction of the receiving beam based on the ephemeris information of the second satellite so that the receiving beam is directed toward the second satellite. The terminal device does not need to perform beam scanning and can effectively reduce the satellite acquisition time of the terminal device, thereby allowing the terminal device to quickly access the second satellite.

[0009] According to a second aspect, an embodiment of the present application provides a communication method applied to a first satellite. It may be understood that the method may be performed by the first satellite or by a chip (system) or circuit used in the first satellite. This is not limited in the present application. The method

[0010] The step of obtaining ephemeris information of the second satellite; and the step of transmitting a first broadcast message, wherein the first broadcast message includes first display information, and the first display information represents the ephemeris information of the second satellite.

[0011] Referring to the second aspect, in a possible embodiment, the step of acquiring the ephemeris information of the second satellite is:

[0012] The method includes the step of receiving first information from a second satellite, wherein the first information includes ephemeris information of the second satellite.

[0013] Referring to a second aspect, in a possible embodiment, the first information further includes at least one of the synchronization signal block (SSB) information of the second satellite, the coverage range of the second satellite, and the load status of the second satellite.

[0014] Referring to the first or second embodiment, in a possible embodiment, the first broadcast message further comprises at least one of SSB information of the second satellite, second display information, or third display information, wherein the second display information indicates the coverage range of the second satellite and the third display information indicates the load status of the second satellite.

[0015] In this embodiment of the present application, the first satellite further broadcasts SSB information of the second satellite so that the terminal device can acquire SSB information of the second satellite (e.g., SSB center frequency or SSB time domain information), and the terminal device can receive the SSB of the second satellite on a fixed frequency channel number without performing frequency scanning, thereby reducing the time for the terminal device to acquire the second satellite. Alternatively, the first satellite further broadcasts the coverage range of the second satellite so that the terminal device can determine whether it is located within the coverage range of the second satellite, and the terminal device can access the second satellite more quickly, thereby significantly reducing the satellite acquisition time for the terminal device. Alternatively, the first satellite further broadcasts the load status of the second satellite so that the terminal device can select a more appropriate second satellite based on the load status, thereby ensuring load balancing between satellites, avoiding long times for subsequent access due to congestion, and ensuring that the second satellite can provide better access service to the terminal device.

[0016] Referring to the first or second embodiment, in a possible embodiment, the second display information indicates the latitude and longitude corresponding to the coverage range of the second satellite.

[0017] In an embodiment of the present application, the second display information indicates the latitude and longitude corresponding to the coverage range of the second satellite, so that the terminal device can quickly determine the coverage range of the second satellite based on the latitude and longitude.

[0018] Referring to the first or second embodiment, in a possible embodiment, the second display information represents an identifier of a geographical area corresponding to the coverage range of the second satellite.

[0019] In this embodiment of the present application, the entire geographical area may be divided into a plurality of geographical areas, and the plurality of geographical areas are numbered to obtain an identifier for each geographical area. The coverage area of ​​the second satellite may be accurately indicated based on the identifier of the geographical area corresponding to the coverage area of ​​the second satellite.

[0020] Referring to the first or second embodiment, in a possible embodiment, the second display information indicates a range of values ​​for the angle formed between a beam radiated by the second satellite and a plane defined by the antenna panel of the second satellite.

[0021] In this embodiment of the present application, a beam emitted by the second satellite can be received within the coverage range of the second satellite. Accordingly, the coverage range of the second satellite can be indicated based on the range of values ​​of the in-angle formed between the beam radiated by the second satellite and the plane defined by the antenna panel of the second satellite. A terminal device can accurately determine the coverage range of the second satellite based on the range of values ​​of the in-angle formed between the beam radiated by the second satellite and the plane defined by the antenna panel of the second satellite.

[0022] Referring to the first or second embodiment, in a possible embodiment, the third display information includes the number of users currently connected to the second satellite and / or the ratio of the number of users currently connected to the second satellite to the number of users allowed to be connected to the second satellite.

[0023] In this embodiment of the present application, the load status of the second satellite may be intuitively reflected based on the number of users currently connected to the second satellite or the ratio of the number of users currently connected to the second satellite to the number of users allowed to be connected to the second satellite.

[0024] Referring to the first or second embodiment, in a possible embodiment, the SSB information comprises at least one of the following information of the second satellite: SSB center frequency, subcarrier spacing (SCS), system frame number (SFN) offset, SSB transmission periodicity, SSB time domain information, and half-frame index.

[0025] In an embodiment of the present application, an SCS, an SFN offset, an SSB transmission periodicity, SSB time domain information, a half-frame index, etc., can be used to determine the SSB time domain position of the second satellite, so that the terminal device can monitor the broadcast signal of the second satellite only at the SSB time domain position of the second satellite (e.g., when the second satellite transmits the SSB). It may not monitor the broadcast signal of the second satellite at other times, and thus the power consumption of the terminal device can be reduced. The SSB information includes the SSB center frequency, so that the terminal device can receive the SSB of the second satellite at a fixed frequency channel number without performing a frequency scan, thereby reducing the time for the terminal device to acquire the second satellite.

[0026] Referring to the first or second embodiment, in a possible embodiment, the first display information includes the ephemeris information of the first satellite and the offset of the ephemeris of the second satellite with respect to the ephemeris of the first satellite.

[0027] Referring to the first or second embodiment, in a possible embodiment, the first broadcast message further includes fourth display information, and the fourth display information indicates that the first broadcast message further includes access information of the first satellite.

[0028] In this embodiment of the present application, the first broadcast message further includes access information of the first satellite so that the terminal device can access the first satellite. For example, after the terminal device fails to access the second satellite, the terminal device can access the first satellite based on the access information of the first satellite.

[0029] Referring to the first embodiment or the second embodiment, in a possible embodiment, the first display information represents ephemeris information of a plurality of satellites, and the second satellite is one of the plurality of satellites that is closer to the terminal device, or the second satellite is one of the plurality of satellites that has a distance to the terminal device below a distance threshold.

[0030] In an embodiment of the present application, a second satellite satisfying the conditions is selected from a plurality of satellites based on the distance between the plurality of satellites and the terminal device to ensure that the second satellite provides better access services to the terminal device.

[0031] Referring to the first or second embodiment, in a possible embodiment, the first display information represents the ephemeris information of a plurality of satellites, and the second satellite is one of a plurality of satellites having a longer service duration or the second satellite is one of a plurality of satellites having a service duration greater than or equal to a time threshold.

[0032] In an embodiment of the present application, a terminal device can select a second satellite from a plurality of satellites that satisfies the condition of service duration, thereby preventing the terminal device from frequently switching between service satellites, and the second satellite can provide better access service to the terminal device.

[0033] Referring to the first embodiment or the second embodiment, in a possible embodiment, the first display information represents the ephemeris information of a plurality of satellites, and the second satellite is one of the plurality of satellites having a higher signal quality, or the second satellite is one of the plurality of satellites having a signal quality greater than or equal to a signal quality threshold.

[0034] In an embodiment of the present application, the terminal device can select a second satellite from a plurality of satellites whose signal quality satisfies the requirements and ensure the service quality of the access service provided by the second satellite to the terminal device.

[0035] According to a third aspect, an embodiment of the present application provides a communication method applied to a second satellite. It may be understood that this method may be performed by the second satellite, or by a chip (system) or a circuit used in the second satellite. This is not limited in the present application. The method

[0036] The step of transmitting first information to a first satellite, wherein the first information includes ephemeris information of a second satellite; and the step of transmitting a second broadcast message.

[0037] In this embodiment of the present application, the second satellite can send the second satellite's ephemeris information to the first satellite, so that the first satellite can broadcast the second satellite's ephemeris information.

[0038] Referring to a third aspect, in a possible embodiment, the first information further comprises at least one of the following: synchronization signal block SSB information of the second satellite, coverage range of the second satellite, and load status of the second satellite.

[0039] In this embodiment of the present application, the second satellite further transmits SSB information, the coverage range of the second satellite, or the load status of the second satellite to the first satellite, so that the first satellite can broadcast the SSB information, the coverage range of the second satellite, or the load status of the second satellite, thereby supporting a terminal device in acquiring the second satellite and reducing the time required to acquire the second satellite.

[0040] According to a fourth aspect, an embodiment of the present application provides a communication device configured to perform a method according to any one of the first aspect or a possible embodiment of the first aspect. The communication device includes a unit that performs a method according to any one of the first aspect or a possible embodiment of the first aspect.

[0041] According to a fifth aspect, an embodiment of the present application provides a communication device configured to perform a method according to any one of the second aspect or a possible embodiment of the second aspect. The communication device includes a unit that performs a method according to any one of the second aspect or a possible embodiment of the second aspect.

[0042] According to the sixth aspect, an embodiment of the present application provides a communication device configured to perform a method according to the third aspect or any one of a possible embodiment of the third aspect. The communication device includes a unit that performs a method according to the third aspect or any one of a possible embodiment of the third aspect.

[0043] In the fourth, fifth, or sixth embodiment, the communication device may include a transceiver unit and a processing unit. For a detailed description of the transceiver unit and the processing unit, refer to the device embodiments below.

[0044] According to a seventh aspect, one embodiment of the present application provides a communication device. The communication device includes a processor configured to perform a method according to any one of the first to third aspects or possible embodiments of the first to third aspects. Alternatively, the processor is configured to execute a program stored in memory. When the program is executed, a method according to any one of the first to third aspects or possible embodiments of the first to third aspects is performed.

[0045] In a possible implementation, the memory is located outside the communication device.

[0046] In a possible implementation, the memory is located inside the communication device.

[0047] In this embodiment of the present application, the processor and memory may alternatively be integrated into a single device. In other words, the processor and memory may alternatively be integrated together.

[0048] In a possible embodiment, the communication device further includes a transceiver. The transceiver is configured to receive a signal or transmit a signal.

[0049] According to an eighth aspect, one embodiment of the present application provides a communication device. The communication device includes a logic circuit and an interface. The logic circuit is connected to the interface. The interface is configured to input a first broadcast message. The logic circuit is configured to input a second broadcast message through the interface based on first display information.

[0050] For a communication device according to the eighth embodiment, it may be understood that reference is made to the first embodiment or specific embodiments below.

[0051] According to a ninth aspect, an embodiment of the present application provides a communication device. The communication device includes a logic circuit and an interface. The logic circuit is connected to the interface. The logic circuit is configured to acquire ephemeris information of a second satellite. The interface is configured to output a first broadcast message.

[0052] With respect to the communication device according to the ninth embodiment, it may be understood that reference is made to the second embodiment or the specific embodiment below.

[0053] According to the tenth aspect, one embodiment of the present application provides a communication device. The communication device includes a logic circuit and an interface. The logic circuit is connected to the interface. The interface is configured to output a first information and a second broadcast message.

[0054] With respect to the communication device according to the 10th embodiment, it may be understood that the 3rd embodiment or the specific embodiment below is referred to.

[0055] According to the eleventh aspect, an embodiment of the present application provides a computer-readable storage medium. The computer-readable storage medium is configured to store a computer program. When the computer program is executed on a computer, a method according to any one of the first to third aspects or a possible embodiment of the first to third aspects is performed.

[0056] According to the 12th aspect, an embodiment of the present application provides a computer program product. The computer program product includes a computer program. When the computer program is executed on a computer, a method according to any one of the first to third aspects or a possible embodiment of the first to third aspects is performed.

[0057] According to the 13th aspect, an embodiment of the present application provides a computer program. When the computer program is executed on a computer, a method according to any one of the first to third aspects or a possible embodiment of the first to third aspects is performed.

[0058] According to the 14th aspect, an embodiment of the present application provides a communication system. The communication system comprises at least two of the following: a terminal device, a first satellite, and a second satellite. The terminal device is configured to perform a method according to the first aspect or any one of a possible embodiment of the first aspect. The first satellite is configured to perform a method according to the second aspect or any one of a possible embodiment of the second aspect. The second satellite is configured to perform a method according to the third aspect or any one of a possible embodiment of the third aspect. Brief explanation of the drawing

[0059] The following describes the attached drawings in an embodiment of the present application. FIG. 1a is a drawing of the architecture of a communication system according to one embodiment of the present application; FIG. 1b is a drawing of the architecture of another communication system according to one embodiment of the present application; FIG. 1c is a drawing of the architecture of another communication system according to an embodiment of the present application; FIG. 2 is a drawing of beam sweeping according to one embodiment of the present application; FIG. 3 is a schematic flowchart of a communication method according to one embodiment of the present application; FIG. 4 is a schematic flowchart of another communication method according to one embodiment of the present application; FIG. 5 is a schematic flowchart of another communication method according to one embodiment of the present application; FIG. 6 is a diagram of the coverage range of the second satellite according to an embodiment of the present application; FIG. 7 is a schematic flowchart of another communication method according to one embodiment of the present application; FIG. 8 is a drawing of the structure of a communication device according to one embodiment of the present application; FIG. 9 is a drawing of the structure of another communication device according to one embodiment of the present application; and FIG. 10 is a drawing of the structure of another communication device according to one embodiment of the present application. Specific details for implementing the invention

[0060] Terms such as “first,” “second,” etc., in the specification, claims, and accompanying drawings of this application are used merely to distinguish different objects and are not used to limit the order, chronological order, priority, or degree of importance of multiple objects. In the embodiments of this application, “multiple” means two or more. Additionally, terms such as “include” and “have,” and any other variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device comprising a series of steps or units is not limited to the listed steps or units, but instead optionally additionally includes unlisted steps or units, or optionally additionally includes other steps or units unique to these processes, methods, products, or devices. Also, the character “ / ” generally indicates an “or” relationship between related objects.

[0061] The term "Examples" as used herein means that specific features, structures, or characteristics described in combination with the Examples may be included in at least one Example of the Present Application. Phrases depicted at various locations within the Present Application do not necessarily refer to the same Example and are not independent or optional embodiments exclusive to other Examples. It will be explicitly and implicitly understood by those skilled in the art that the Examples described herein may be combined with other Examples.

[0062] With the advancement of information technology, modern communication systems impose more urgent demands regarding communication efficiency, mobility, and diversity. Currently, in certain critical application scenarios in fields such as space communications, aviation communications, maritime communications, and military communications, non-terrestrial network (NTN) communications, represented by non-terrestrial devices such as satellites, unmanned aerial vehicles, and high-altitude platforms, play an irreplaceable role.

[0063] For the convenience of explanation, the following uses a non-ground device represented by a satellite as an example for illustrative purposes.

[0064] Satellite communication offers features such as long communication distances, wide coverage areas, and flexible networking. It can provide communication services to both fixed terminals and various mobile terminals. Existing terrestrial networks cannot provide seamless coverage for terminal devices, particularly in areas where base stations cannot be deployed, such as the ocean, deserts, and the air. Therefore, NTN is being introduced into 5th generation (5G) mobile communication systems. NTN provides seamless coverage communication for terminals by deploying base stations or parts of base station functions on high-altitude platforms or satellites. Additionally, high-altitude platforms or satellites are less affected by natural disasters, which can improve the reliability of 5G systems. In satellite-based NTN, satellites cover the ground using different beams to form satellite cells, and terminal devices can be covered by multiple satellite cells simultaneously.

[0065] Satellite communication systems can be classified into the following three types based on the satellite's orbital altitude.

[0066] Geostationary Earth Orbit (GEO) satellite communication systems, medium Earth Orbit (MEO) satellite communication systems, and low Earth Orbit (LEO) satellite communication systems, also known as geosynchronous orbit satellite systems.

[0067] GEO satellites have an orbital altitude of 35,786 km. The main advantage is that GEO satellites are fixed relative to the ground and can provide a wider communication area. The disadvantages are as follows: (1) GEO satellite orbits are far from Earth, and there is significant signal loss in free space. Consequently, the budget for communication links is insufficient. To increase transmit / receive gain, large-diameter antennas must be configured to fit the satellite. (2) Communication transmission delays are long, and round-trip times can reach approximately 500 ms. This cannot meet the requirements for real-time services. (3) GEO has limited orbital resources, high launch costs, and cannot provide coverage for the Earth's polar regions.

[0068] MEO satellites have orbital altitudes of 2,000 kilometers and 35,786 kilometers. The advantage is that global coverage can be achieved using a small number of satellites. However, MEO satellites have higher orbital altitudes than LEO satellites, and the transmission delay of MEO satellite communication is longer than that of LEO satellite communication. Considering the advantages and disadvantages of MEO satellite communication, MEO satellites are primarily used for positioning and navigation.

[0069] LEO satellites have orbital altitudes of 300 kilometers and 2,000 kilometers. LEO satellites have lower orbital altitudes than MEO and GEO satellites and possess advantages such as short data propagation delay, low transmission loss, and low launch costs. To improve the overall signal processing capability and communication throughput of a satellite network, satellite operators increase the number of satellites to compensate for the limitations of a single satellite in communication capabilities. In future NTN communication systems, after a terminal device accesses the system, multiple satellites capable of communicating with the terminal device become "visible" to each other within a certain period. In this case, all of the multiple satellites can provide communication services to the terminal. This provides the basic conditions for coordinated multi-satellite transmission.

[0070] The technical solutions provided in the embodiments of the present application can be applied to various communication systems, for example, satellite communication systems, and systems in which satellite communication and cellular networks are integrated. Cellular network systems include, but are not limited to, 5G systems, GSM (Global System for Mobile Communications) systems, CDMA (Code Division Multiple Access) systems, WCDMA (Wideband Code Division Multiple Access) systems, GPRS (General Packet Radio Service) systems, LTE (Long Term Evolution) systems, LTE FDD (Frequency Division Duplex) systems, LTE TDD (Time Division Duplex) systems, LTE-A (Long Term Evolution Advanced) systems, NR (New Radio) systems, advanced NR systems, LTE-U (LTE-based Access to Unlicensed Spectrum) systems, NR-U (NR-based Access to Unlicensed Spectrum) systems, UMTS (Universal Mobile Telecommunications System), WiMAX (Worldwide Interoperability for Microwave Access) communication systems, WLAN (Wireless Local Area Network), Wi-Fi (Wireless Fidelity), next-generation communication systems, and other communication systems. Typically, conventional communication systems support a limited number of connections and are easy to implement. However, with the advancement of communication technology, mobile communication systems not only support conventional communication but also, for example, device-to-device (D2D) communication.Machine-to-machine (M2M) communication, machine-type communication (MTC), vehicle-to-vehicle (V2V) communication, and other future advanced communication systems, etc. Embodiments of this application may also be applicable to these communication systems. Satellite communication systems may include various non-ground network systems, for example, networks in which radio frequency transmission is performed by satellites, unmanned aircraft system (UAS) platforms, etc. These are not listed individually herein.

[0071] For example, the following provides a specific application scenario for this solution using an NTN system as an example. Specifically, the NTN system can be a satellite communication system or another non-terrestrial network system. The positioning method in this solution can be applied to satellite communication ranges.

[0072] Refer to FIGS. 1a, 1b, and 1c. For example, a 5G communication system is used. FIGS. 1a, 1b, and 1c are drawings of architectures of various communication systems according to embodiments of the present application.

[0073] As illustrated in FIGS. 1a, 1b, and 1c, one or more terminal devices (e.g., mobile terminals) and / or network devices (e.g., 5G base stations) may be present in the coverage area of ​​the satellite cell. The coverage area of ​​the cell may be an area covered by one or more beams of the satellite, or an area at the same level as the cell in an NR system.

[0074] As illustrated in FIG. 1a, a ground terminal device (e.g., a mobile terminal) accesses the network through an air interface, and a network device (e.g., a 5G base station) can be deployed on the ground and directly connected to a ground 5G core network via a ground-centric link, or connected to a ground station for satellite communication. This type of communication architecture is also referred to as a transparent satellite network architecture. Thus, the base station is located on the ground. Additionally, wireless links exist between satellites to complete signal exchange and user data transmission between base stations.

[0075] As illustrated in FIG. 1b, a ground terminal device (e.g., a mobile terminal) accesses the network through an air interface, and a network device (e.g., a 5G base station) can be deployed on a satellite and connected to a ground 5G core network via a wireless link and a ground station. This type of communication architecture is also referred to as a regenerative satellite network architecture. Thus, a base station or part of the base station's functions reside on the satellite. Additionally, wireless links exist between the satellites to complete signal exchange and user data transmission between base stations.

[0076] As illustrated in FIG. 1c, a ground terminal device (e.g., a mobile terminal) accesses the network via an air interface, and a network device (e.g., a 5G base station) or part of the network device's functions (e.g., a 5G base station) is deployed on a satellite and connected to a ground 5G core network via a radio link and a ground station. Part of the network device's functions (e.g., a 5G base station) is deployed on the ground and directly connected to the ground 5G core network via a radio link and connected to a ground station for satellite communication. Thus, in this type of communication architecture, the base station or part of the base station's functions is located on the satellite and on the ground, respectively. Additionally, a radio link exists between the satellites to complete signal exchange and user data transmission between the base stations.

[0077] In actual deployment, it may be understood that the satellite in the aforementioned system may alternatively be another NTN device, for example, a high-altitude platform station (HAPS). This is not limited to the present application.

[0078] The network elements and their interfaces in the scenario are described as follows.

[0079] Terminal device: A terminal device is a mobile device that supports 5G New Radio, typically a mobile device such as a user terminal or a wearable device. The terminal device can access a satellite network through an air interface and initiate services such as calling or network access.

[0080] 5G Base Station: A 5G base station primarily provides wireless access services, schedules wireless resources for access terminals, and provides reliable wireless transmission protocols, data encryption protocols, etc.

[0081] 5G Core Network: The 5G core network includes services such as user access control, mobility management, session management, user security authentication, and billing. The 5G core network comprises multiple functional units and can be divided into control plane functional entities and data plane functional entities. The access and mobility management function (AMF) is responsible for user access management, security authentication, and mobility management. The location management function (LMF) manages and controls location service requests from target terminals and processes location-related information. The user plane function (UPF) manages functions such as user plane data transmission and traffic statistics.

[0082] Ground station: The ground station plays the role of transmitting signal and service data between the satellite base station and the 5G core network.

[0083] 5G New Radio: 5G New Radio is a wireless link between user equipment and a base station.

[0084] Xn Interface: The Xn interface is an interface between 5G base stations and is primarily configured for signal exchange such as handover.

[0085] NG Interface: The NG interface is an interface between a 5G base station and a 5G core network, and is primarily used for exchanging signals such as non-access stratum (NAS) signals of the core network and user service data.

[0086] The technical solution provided in this application is primarily related to two execution entities. Network devices and terminal devices can be applied to communication processes of communication systems such as 5G, particularly non-terrestrial networks.

[0087] In the embodiments of the present application, terminal devices include, but are not limited to, terminal devices connected via wired lines, e.g., a public switched telephone network (PSTN), a digital subscriber line (DSL), digital cable, direct cable connection, and / or other data connection networks; and / or terminal devices connected via wireless interfaces such as cellular networks, wireless local area networks (WLAN), digital television networks such as digital video broadcast-handheld (DVB-H) networks, satellite networks, and amplitude modulation-frequency modulation (AM-FM) broadcast transmitters; and / or devices of other terminal devices configured to receive / transmit communication signals; and / or Internet of Things (IoT) devices. A terminal device configured to communicate via a wireless interface may be referred to as a "wireless communication terminal," a "wireless terminal," or a "mobile terminal." Examples of terminal devices include, but are not limited to: a satellite phone or a cellular phone; A Personal Communication System (PCS) terminal capable of combining a cellular wireless phone with data processing, fax, and data communication capabilities; a Personal Digital Assistant (PDA) that may include a wireless phone, pager, internet / intranet access, web browser, planner, calendar, and / or Global Positioning System (GPS) receiver; and a conventional laptop and / or handheld receiver or other electronic device comprising a wireless phone transceiver.A terminal device may be referred to as user equipment (UE), access terminal, subscriber device, subscriber station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, or user device. Alternatively, a terminal device may be a cellular phone, a wireless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a PDA, a handheld device with wireless communication capabilities, a computing device, another processing device connected to a wireless modem, a vehicle-mounted device, a wearable device, a terminal device in a 5G network, a terminal device in a future evolving public land mobile network (PLMN), etc.

[0088] In embodiments of the present application, a network device may provide communication coverage in a specific geographic area, communicate with one or more terminal devices located within the coverage area, and may be configured to communicate with one or more base stations having a portion of terminal functions (e.g., communication between a macro base station and a micro base station such as an access point). Optionally, the network device may be a satellite, a base transceiver station (BTS) in a GSM system or an evolved Node B (eNB) in a CDMA system or LTE system, a next generation node base station (gNB) in a 5G system or NR system, another satellite base station, or a satellite relay node. Alternatively, the network device may be an access point (AP), a transport point (TRP), a central unit (CU), or other network entity, and may include some or all of the functions of the aforementioned network entities.

[0089] In the embodiments of this application, a device having communication functions in a network / system may be understood to be referred to as a communication device. The communication system illustrated in FIGS. 1a, 1b, and 1c has been used as an example. A communication device may include a network device and a terminal device having communication functions. The network device and the terminal device may be the specific devices described above. Details are not described further herein. A communication device may further include other devices within the communication system, e.g., a network controller, a mobility management entity, or other network entities. This is not limited to the embodiments of this application.

[0090] It should be further noted that in this application, the expressions "satellite" and "satellite network device" are equivalent. That is, the satellite mentioned in this application refers to a satellite and a set of other network devices related to satellite communication.

[0091] It may be understood that a cell in an NTN system may be a projection area of ​​a beam of a satellite on the ground, a projection area of ​​multiple beams of a satellite on the ground, or a part of a projection area of ​​one or more beams on the ground. This is not limited to the embodiments of the present application.

[0092] In an NTN system, a satellite can transmit synchronization signal blocks (SSBs) using a beam sweeping method. To align with the satellite, a terminal device must perform frequency scanning and beam scanning. The terminal device needs to scan for SSBs transmitted by the satellite in multiple beam directions across multiple frequencies. For a single frequency, the terminal device needs to scan for SSBs transmitted by the satellite in beam directions, and the time required for the terminal device to scan a single frequency is determined by the SSB sweeping periodicity and the amount of beams required for the terminal device to complete the scanning. If the terminal device needs to scan multiple frequencies, the time required for the terminal device to acquire the satellite is directly proportional to the amount of frequencies to be scanned. For example, as illustrated in Fig. 2, the terminal device lacks built-in satellite ephemeries information, the antenna specifications of the terminal device are a 32 × 32 antenna array, the 3 dB beam width of the terminal device is 3.2 degrees, the maximum scan angle of the terminal device is 60 degrees, the amount of beam required for the terminal device to complete scanning is approximately 2614, and the SSB sweeping periodicity is 20 ms. Therefore, the time required for the terminal device to search for a single frequency is 2614 × 20 ms = 52.28 seconds, which is a long time. Particularly for terminal devices located in edge beam positions, because it takes a long time for the terminal device to acquire a satellite, the satellite may have moved far away and no longer cover the terminal device during the process of beam alignment to the satellite. Consequently, the terminal device must perform frequency scanning and beam scanning again to acquire the next satellite, resulting in a long satellite acquisition time for the terminal device.

[0093] With this in mind, embodiments of the present application provide a communication method for effectively reducing the satellite acquisition time for a terminal device. The method provided in the embodiments of the present application may be applied to the system illustrated in FIG. 1a, FIG. 1b, or FIG. 1c.

[0094] Although relay nodes are not included in the method described below, those skilled in the art will recognize that when the transmitting end and the receiving end communicate with each other, a forwarding operation can be performed by a relay node.

[0095] It will be understood that in the interaction diagrams of this application, the method is illustrated by using examples in which a network device and a terminal device function as execution entities of the interaction. However, the execution entities of the interaction examples in this application are not limited. For example, in the interaction diagram, the network device may alternatively be a chip, chip system, or processor supporting the network device when implementing the method, or a logical node, logic module, or software capable of implementing all or part of the functions of the network device. In the interaction diagram, the terminal device may alternatively be a chip, chip system, or processor supporting the terminal when implementing the method.

[0096] FIG. 3 is a schematic flowchart of a communication method according to one embodiment of the present application. As shown in FIG. 3, the method includes, but is not limited to, the following steps.

[0097] Optionally, the method illustrated in FIG. 3 may include step 301.

[0098] 301: The second satellite sends the first information, and in response, the first satellite receives the first information, and the first information includes the second satellite's ephemeris information.

[0099] 302: The first satellite transmits a first broadcast message, and in response, the terminal device receives the first broadcast message. The first broadcast message includes first display information, and the first display information represents the ephemeris information of the second satellite.

[0100] For example, the coverage range of the first satellite is greater than that of the second satellite. Alternatively, the orbital altitude of the first satellite is higher than that of the second satellite. The first satellite may be referred to as a high-orbit satellite, and the second satellite as a low-orbit satellite. For example, the first satellite may be a GEO satellite, and the second satellite may be an LEO satellite. The second satellite may be located within the coverage range of the first satellite.

[0101] In one example, the first display information includes the ephemeris information of the second satellite.

[0102] In another example, the first display information includes the ephemeris information of the first satellite and the offset of the ephemeris of the second satellite relative to the ephemeris of the first satellite. The terminal device can determine the ephemeris information of the second satellite based on the first display information. For example, if the ephemeris information of the first satellite includes the coordinates, direction, velocity, and other parameters of the first satellite, the first display information includes the difference between the coordinates of the second satellite and the coordinates of the first satellite, the difference between the direction of the second satellite and the direction of the first satellite, the difference between the velocity of the second satellite and the velocity of the first satellite, etc.

[0103] For example, the first broadcast message may be a system information block (SIB) message transmitted by the first satellite. The first broadcast message may include access information of the first satellite, or it may not include access information of the first satellite.

[0104] In one example, the first broadcast message may be a newly defined SIB1 information element, e.g., IE SIB1-lightweight. The first broadcast message may not include access information, SI scheduling information, and other information of the first satellite, but includes first indication information representing the ephemeris information of the second satellite.

[0105] In another example, the fourth indicator information may indicate whether the first broadcast message includes access information of the first satellite. For example, the first broadcast message includes the fourth indicator information, and the fourth indicator information indicates that the first broadcast message further includes access information of the first satellite. The first broadcast message may be a SIB1 message specified in the NR protocol. The fourth indicator information may include a flag identifier (FlagAccessOther), and the value of the flag identifier indicates whether the first broadcast message includes access information of the first satellite. For example, when the flag identifier is 1, this indicates that the first broadcast message includes access information of the first satellite. When the flag identifier is 0, this indicates that the first broadcast message does not include access information of the first satellite.

[0106] It should be understood that the value of the flag identifier is merely an example and should not be understood as a limitation to the present application. In the embodiments of the present application, the value of the flag identifier may alternatively be a different value. This is not limited to the present application.

[0107] In a possible embodiment, the first broadcast message further includes at least one of SSB information of the second satellite, second display information, or third display information, wherein the second display information indicates the coverage range of the second satellite and the third display information indicates the load status of the second satellite.

[0108] For example, a terminal device can search for a broadcast signal of a first satellite by means of frequency scanning or beam scanning, synchronize with the first satellite, and acquire a first broadcast message.

[0109] In a possible embodiment, the first display information represents the ephemeris information of a plurality of satellites, and the method illustrated in FIG. 3 further includes step 303.

[0110] 303: The terminal device selects a second satellite from a plurality of satellites based on the first display information.

[0111] The orbital altitude of multiple satellites is lower than the orbital altitude of the first satellite, or the coverage range of each of the multiple satellites is smaller than the coverage range of the first satellite. For example, the multiple satellites are located within the coverage range of the first satellite.

[0112] For example, the first display information may include an ephemeris information list, and the ephemeris information list includes ephemeris information of a plurality of satellites or an offset of ephemeris information of a plurality of satellites for the ephemeris of the first satellite. For example, the ephemeris information list may be as shown in Table 1. N satellites are used as examples in Table 1. Satellite 1_1 corresponds to ephemeris information 1_1,... and satellite 1_N corresponds to ephemeris information 1_N.

[0113] Satellite list Ephemeris Information List Satellite 1_1 Ephemeris Information 1_1 Satellite 1_2 Ephemeris Information 1_2 … … Satellite 1_N Ephemeris Information 1_N

[0114] A terminal device may select a second satellite as a target access satellite among a plurality of satellites based on the terminal device's global navigation satellite system (GNSS) position. In the example, the second satellite is one of the plurality of satellites that is closer to the terminal device, or the second satellite is one of the plurality of satellites that has a distance to the terminal device below a distance threshold. For example, the second satellite may be the satellite closest to the terminal device among the plurality of satellites. The distance threshold may be configured by a network, predefined in a protocol, or determined based on the terminal device's service requirements or the terminal device's capabilities.

[0115] In this example, the second satellite satisfying the conditions is selected from a plurality of satellites based on the distance between the plurality of satellites and the terminal device to ensure that the second satellite provides better access services to the terminal device.

[0116] In another example, the second satellite is one of a plurality of satellites having a longer service duration, or the second satellite is one of a plurality of satellites having a service duration greater than a time threshold. For example, the terminal device may determine the service duration of a plurality of satellites based on the ephemeris information of the plurality of satellites and select a second satellite from the plurality of satellites that satisfies the conditions based on the service duration of the plurality of satellites. For example, the second satellite may be one of a plurality of satellites having the longest service duration. It will be understood that the time threshold may be configured by the network, predefined by a protocol, or determined based on the service requirements of the terminal device.

[0117] In this example, the terminal device can select a second satellite from a plurality of satellites that satisfies the service duration condition, so that the terminal device can prevent frequent switching between service satellites and the second satellite can provide better access service to the terminal device.

[0118] In another example, the second satellite is one of the plurality of satellites having a higher signal quality, or the second satellite is one of the plurality of satellites having a signal quality greater than or equal to a signal quality threshold. For example, the signal quality of the second satellite can be expressed as the reference signal received power (RSRP) or reference signal received quality (RSRQ) corresponding to the second satellite. For example, the higher the PSRP of the second satellite, the higher the signal quality of the second satellite. As another example, a larger PSRQ of the second satellite indicates a higher signal quality of the second satellite. The terminal device can determine the positions or orientations of the plurality of satellites based on the ephemeris information of the plurality of satellites, and can obtain the signal quality of each of the plurality of satellites by separately receiving reference signals transmitted by the plurality of satellites. Then, the terminal device selects the second satellite from the plurality of satellites that has a higher signal quality or a signal quality greater than or equal to a signal quality threshold as the target access satellite.

[0119] In this example, the terminal device can select a second satellite from a plurality of satellites whose signal quality satisfies the requirements, and guarantee the service quality of the access service provided by the second satellite to the terminal device.

[0120] 304: The second satellite transmits a second broadcast message, and in response, the terminal device receives the second broadcast message from the second satellite based on the first display information.

[0121] For example, the terminal device determines the position or direction of the second satellite based on the first display information and adjusts the direction of the receiving beam so that the receiving beam is directed toward the second satellite in order to monitor the broadcast signal of the second satellite. The second broadcast message may be an SIB message transmitted by the second satellite, and the terminal device may access the second satellite based on the second broadcast message.

[0122] In some possible embodiments, after the terminal device receives the second broadcast message, the method illustrated in FIG. 3 further includes step 305.

[0123] 305: The terminal device sends a preamble, and the second satellite receives the preamble accordingly.

[0124] The terminal device can perform an access procedure based on the preamble (Msg1) to access the second satellite.

[0125] In the embodiments of the present application, the coverage range of the first satellite is greater than the coverage range of the second satellite. The first satellite can broadcast the ephemeris information of the second satellite, so that the terminal device can acquire the ephemeris information of the second satellite and can adjust the direction of the receiving beam based on the ephemeris information of the second satellite so that the receiving beam is directed toward the second satellite. The terminal device does not need to perform beam scanning and effectively reduces the satellite acquisition time of the terminal device, so that the terminal device can quickly access the second satellite.

[0126] In some possible embodiments, the ephemeris information in the embodiments of the present application may alternatively be replaced with position information or orbit information. That is, the first display information represents the position information or orbit information of the second satellite. For example, the first display information may include the position information or orbit information of the second satellite. As another example, the first display information may include the position information of the first satellite and an offset of the position of the second satellite relative to the position of the first satellite, or the first display information may include the orbit information of the first satellite and an offset of the orbit of the second satellite relative to the orbit of the first satellite.

[0127] FIG. 4 is a schematic flowchart of another communication method according to one embodiment of the present application. As shown in FIG. 4, the method includes, but is not limited to, the following steps.

[0128] Optionally, the method illustrated in FIG. 4 may include step 401.

[0129] 401: The second satellite sends first information, and in response, the first satellite receives first information, and the first information includes the second satellite's ephemeris information and SSB information.

[0130] 402: The first satellite transmits a first broadcast message, and in response, a terminal device receives the first broadcast message. The first broadcast message includes first display information and SSB information of the second satellite, and the first display information represents the ephemeris information of the second satellite.

[0131] In one example, SSB information may include at least one of the following: SSB center frequency, subcarrier spacing (SCS), system frame number (SFN) offset, SSB transmission periodicity, SSB time-domain position information, half-frame index, and SSB measurement timing configuration (SMTC).

[0132] In another example, the first broadcast message may include an offset between the SSB information of the second satellite and the SSB information of the first satellite. For example, the first broadcast message includes the difference between the SSB center frequency of the second satellite and the SSB center frequency of the first satellite, the difference between the SSB transmission periodicity of the second satellite and the SSB transmission periodicity of the first satellite, the difference between the SSB transmission time of the second satellite and the SSB transmission time of the first satellite, and other offsets.

[0133] In a possible embodiment, the first broadcast message includes ephemeris information of a plurality of satellites and SSB information of a plurality of satellites. For example, the ephemeris information and SSB information of a plurality of satellites may be included in the first broadcast message in the form of a table. As shown in Table 2, an example involving N satellites is used. The first broadcast message may include ephemeris information and SSB information of N satellites.

[0134] Satellite list Ephemeris Information List SSB Information Satellite 1_1 Ephemeris Information 1_1 It includes SSB center frequency, SSB transmission periodicity, SMTC, etc. Satellite 1_2 Ephemeris Information 1_2 It includes SSB center frequency, SSB transmission periodicity, SMTC, etc. … … … Satellite 1_N Ephemeris Information 1_N It includes SSB center frequency, SSB transmission periodicity, SMTC, etc.

[0135] Optionally, the method illustrated in FIG. 4 may further include step 403. 403: The terminal device selects a second satellite from a plurality of satellites based on first display information.

[0136] The terminal device can select a second satellite as a target access satellite among a plurality of satellites based on GNSS position.

[0137] It can be understood that for a detailed description of Step 403, refer to the relevant description in Step 303. Details are not described again herein.

[0138] For the first broadcast message, the first display information, and the relevant descriptions of the second satellite, it will be understood that reference is made to the relevant descriptions in step 302 of FIG. 3. Details are not described further herein.

[0139] 404: Based on the ephemeris information of the second satellite, the terminal device directs the receiving beam of the terminal device toward the second satellite and receives a second broadcast message from the second satellite at the SSB center frequency.

[0140] The terminal device can adjust the direction of the receiving beam of the terminal device based on the ephemeris information of the second satellite so that the receiving beam is directed toward the second satellite and monitor the broadcast signal of the second satellite at the SSB center frequency to receive the second broadcast message.

[0141] For example, the terminal device can additionally determine the SSB time-domain location of the second satellite based on the SSB information of the second satellite, and can monitor the broadcast signal of the second satellite at the SSB time-domain location of the second satellite (e.g., when the second satellite transmits the SSB), and can not monitor the broadcast signal of the second satellite at other times, thereby reducing the power consumption of the terminal device.

[0142] In some possible embodiments, after the terminal device receives the second broadcast message, the method illustrated in FIG. 4 further includes step 405.

[0143] 405: The terminal device sends a preamble, and the second satellite receives the preamble accordingly.

[0144] The terminal device can perform an access procedure based on the preamble to access the second satellite.

[0145] In the embodiments of the present application, the coverage range of the first satellite is greater than the coverage range of the second satellite. The first satellite can broadcast the ephemeris information and SSB information of the second satellite, and the terminal device does not need to perform beam scanning and frequency scanning, and the satellite acquisition time of the terminal device can be effectively shortened so that the terminal device can quickly access the second satellite.

[0146] FIG. 5 is a schematic flowchart of another communication method according to one embodiment of the present application. As shown in FIG. 5, the method includes, but is not limited to, the following steps.

[0147] Optionally, the method illustrated in FIG. 5 may include step 501.

[0148] 501: The second satellite sends first information, and in response, the first satellite receives first information, and the first information includes the second satellite's epimeris information and the second satellite's coverage range.

[0149] 502: The first satellite transmits a first broadcast message, and in response, a terminal device receives the first broadcast message. The first broadcast message includes first display information and second display information, wherein the first display information indicates the ephemeris information of the second satellite and the second display information indicates the coverage range of the second satellite.

[0150] In one example, the second display information indicates the latitude and longitude corresponding to the coverage range of the second satellite. The second display information includes a longitude range and a latitude range within the coverage range of the second satellite, and the terminal device can determine whether the terminal device is located within the coverage range of the second satellite based on the GNSS information of the terminal device. In this example, since the second display information indicates the latitude and longitude corresponding to the coverage range of the second satellite, the terminal device can quickly determine the coverage range of the second satellite based on the latitude and longitude.

[0151] In another example, the second display information represents an identifier of a geographical area corresponding to the coverage range of the second satellite. In this example, the entire geographical area may be divided into multiple geographical areas, and the multiple geographical areas are numbered to obtain an identifier for each geographical area. The first satellite may determine the geographical area included in the coverage range of the second satellite based on interaction with the second satellite. For example, the second satellite reports the coverage range of the second satellite to the first satellite, the first satellite obtains the coverage range of the second satellite, determines the geographical area included in the coverage range of the second satellite, and broadcasts the identifier of the geographical area corresponding to the coverage range of the second satellite using a first broadcast message. In yet another example, the second satellite reports the identifier of the geographical area included in the coverage range of the second satellite to the first satellite, and the first satellite broadcasts the identifier of the geographical area corresponding to the coverage range of the second satellite by using the first broadcast message.

[0152] For example, the terminal device stores a mapping relationship between an identifier and a geographic area. Based on the GNSS information of the terminal device, the terminal device determines the geographic area where the terminal device is located, and compares the identifier of the geographic area where the terminal device is located with the identifier of the geographic area corresponding to the coverage range of the second satellite to determine whether the terminal device is located within the coverage range of the second satellite.

[0153] In this example, the coverage area of ​​the second satellite can be accurately indicated based on the identifier of the geographical area corresponding to the coverage range of the second satellite.

[0154] In another example, the second display information indicates a range of values ​​for the in-beam angle formed between a beam radiated by the second satellite and a plane defined by the antenna panel of the second satellite. The beam radiated by the second satellite can be received within the coverage range of the second satellite. Accordingly, the coverage range of the second satellite can be displayed based on the range of values ​​for the in-beam angle formed between a beam radiated by the second satellite and a plane defined by the antenna panel of the second satellite. For example, the second display information may indicate the minimum value of the in-beam angle formed between a beam radiated by the second satellite and a plane defined by the antenna panel of the second satellite. The terminal device can determine whether the terminal device is within the coverage range of the second satellite by comparing whether the first in-beam angle is included in the value range. The first in-beam angle is the in-beam angle formed between a line connecting the terminal device to a reference point on a plane defined by the antenna panel and the plane defined by the antenna panel.

[0155] Alternatively, the second display information represents the maximum value of the in-between angle formed between the beam emitted by the second satellite and the normal of the antenna panel of the second satellite, and the normal of the antenna panel of the second satellite is perpendicular to the plane defined by the antenna panel of the second satellite. The maximum value of the in-between angle formed between the beam radiated by the second satellite and the normal of the antenna panel of the second satellite may also be referred to as the maximum scan angle. As illustrated in FIG. 6, the normal of the antenna panel of the second satellite points toward the center of the Earth. The terminal device determines the in-between angle formed between the terminal device and the normal of the antenna panel of the second satellite based on the GNSS information of the terminal device and the ephemeris information of the second satellite. If the in-between angle formed between the line connecting the terminal device to a reference point on the antenna panel and the normal of the antenna panel is less than the maximum scan angle of the second satellite, the terminal device is within the coverage range of the second satellite.

[0156] For example, the second display information may further indicate the indentation formed between the plane formed by the antenna panel and the ground, or the indentation formed between the antenna panel and the normal of the ground and the center of the Earth. When the plane defined by the antenna panel of the second satellite is not parallel to the ground, or when the normal of the antenna panel of the second satellite does not point toward the center of the Earth, the terminal device may determine the coverage range of the second satellite based on the value range of the indentation formed between the beam radiated by the second satellite and the plane defined by the antenna panel of the second satellite, and the indentation formed between the plane defined by the antenna panel and the ground, or the indentation formed between the antenna panel and the center of the Earth and the ground, thereby determining whether the terminal device is located within the coverage range of the second satellite.

[0157] For example, the second display information further displays the coverage ranges of multiple satellites. For example, the ephemeris information and the coverage ranges of multiple satellites may be included in the first broadcast message in the form of a table. As shown in Table 3, an example involving N satellites is used. The first broadcast message may include the ephemeris information and coverage ranges of N satellites. In the case of satellite 1_1, the ephemeris information is ephemeris information 1_1, and the coverage range is coverage range 1_1.

[0158] Satellite list Ephemeris Information List Coverage range Satellite 1_1 Ephemeris Information 1_1 Coverage Range 1_1 Satellite 1_2 Ephemeris Information 1_2 Coverage range 1_2 … … … Satellite 1_N Ephemeris Information 1_N Coverage range 1_N

[0159] Optionally, the method illustrated in FIG. 5 may further include step 503. 503: The terminal device selects a second satellite from a plurality of satellites based on second display information.

[0160] For example, the terminal device is located within the coverage range of the second satellite. Based on the GNSS position and the second display information, the terminal device may determine that the terminal device is located within the coverage range of the second satellite and may select the second satellite as the target access satellite. Based on the GNSS position, the terminal device may select a satellite that covers the terminal device from among a plurality of satellites as a candidate satellite, and the candidate satellites include the second satellite. If the number of candidate satellites is 1, the terminal device selects the satellite (i.e., the second satellite) as the target access satellite and accesses the satellite. If the number of candidate satellites is greater than 1, the second satellite is a satellite among the candidate satellites that satisfies the conditions. For example, the second satellite is one of the candidate satellites that is closer to the terminal device, or the second satellite is one of the candidate satellites that has a longer service duration, or the second satellite is one of the candidate satellites that has a higher signal quality.

[0161] 504: The second satellite broadcasts a second broadcast message, and in response, the terminal device receives the second broadcast message from the second satellite based on the first display information.

[0162] For a specific implementation of step 504, refer to the specific implementation of step 304 in FIG. 3. Details are not described further herein.

[0163] For descriptions related to the first broadcast message, first instruction information, and second satellite, refer to the relevant description in step 302 of FIG. 3. Details are not described herein.

[0164] In some possible embodiments, after the terminal device receives the second broadcast message, the method illustrated in FIG. 5 further includes step 505.

[0165] 505: The terminal device sends a preamble, and the second satellite receives the preamble accordingly.

[0166] The terminal device can perform an access procedure based on the preamble to access the second satellite.

[0167] In this embodiment of the present application, the first satellite can broadcast the ephemeris information and coverage range of the second satellite, so that the terminal device can determine whether the terminal device is located within the coverage range of the second satellite, and the terminal device accesses the second satellite more quickly, thereby significantly reducing the satellite acquisition time of the terminal device.

[0168] FIG. 7 is a schematic flowchart of another communication method according to one embodiment of the present application. As shown in FIG. 7, the method includes, but is not limited to, the following steps.

[0169] Optionally, the method illustrated in FIG. 7 may include step 701.

[0170] 701: The second satellite sends first information to the first satellite, and accordingly, the first satellite receives first information. The first information includes the ephemeris information of the second satellite and the load status of the second satellite.

[0171] 702: The first satellite transmits a first broadcast message, and in response, a terminal device receives the first broadcast message. The first broadcast message includes first display information and third display information, wherein the first display information indicates the ephemeris information of the second satellite and the third display information indicates the load status of the second satellite.

[0172] For example, the third display information includes the number of users currently connected to the second satellite and / or the ratio of the number of users currently connected to the second satellite to the number of users allowed to connect to the second satellite.

[0173] Optionally, the first display information represents the ephemeris information of a plurality of satellites, and the third display information represents the load status of a plurality of satellites. The ephemeris information and load status of a plurality of satellites may be included in the first broadcast message in the form of a table. As shown in Table 4, an example involving N satellites is used. The first broadcast message may include ephemeris information and the load status of N satellites. In the case of satellite 1_1, the ephemeris information is ephemeris information 1_1 and the load status is load status 1_1.

[0174] Satellite list Ephemeris Information List Load status Satellite 1_1 Ephemeris Information 1_1 Load status 1_1 Satellite 1_2 Ephemeris Information 1_2 Load state 1_2 … … … Satellite 1_N Ephemeris Information 1_N Load state 1_N

[0175] Optionally, the method illustrated in FIG. 7 may further include step 703. 703: A terminal device selects a second satellite from a plurality of satellites based on GNSS information, first display information, and third display information.

[0176] For example, the second satellite is a satellite having a better load condition among a plurality of satellites. Specifically, the terminal device may select the satellite having a better load condition from a plurality of satellites based on the load condition of the plurality of satellites. For example, the second satellite may be one of a plurality of satellites having a smaller number of currently connected users, or the second satellite is one of a plurality of satellites having a smaller ratio of the number of currently connected users to the number of users that can be connected.

[0177] 704: The second satellite broadcasts a second broadcast message, and in response, the terminal device receives the second broadcast message from the second satellite based on the first display information.

[0178] For a specific embodiment of step 704, reference may be made to a specific embodiment of step 304 of FIG. 3. Details are not described herein.

[0179] For descriptions related to the first broadcast message, first instruction information, and second satellite, refer to the relevant description in step 302 of FIG. 3. Details are not described herein.

[0180] In some possible embodiments, after the terminal device receives the second broadcast message, the method illustrated in FIG. 7 further includes step 705.

[0181] 705: The terminal device sends a preamble, and the second satellite receives the preamble accordingly.

[0182] The terminal device can perform an access procedure based on the preamble to access the second satellite.

[0183] In this embodiment of the present application, the first satellite can broadcast the ephemeris information and load status of the second satellite, so that the terminal device can select a more appropriate second satellite based on the load status, thereby ensuring load balancing between satellites, avoiding long times for subsequent access caused by congestion, and ensuring that the second satellite can provide better access service to the terminal device.

[0184] It is understood that embodiments may be combined with one another. Specifically, the first broadcast message includes at least one of first display information and SSB information, second display information, or third display information. For example, the method illustrated in FIG. 4 may be combined with the method illustrated in FIG. 5. Specifically, the first broadcast message includes first display information, SSB information, and second display information. Details are not described herein.

[0185] The following describes the device provided in the embodiments of the present application.

[0186] In the present application, a communication device is divided into functional modules based on the method embodiment described above. For example, each functional module may be obtained through division based on each corresponding function, or two or more functions may be integrated into a single processing module. The integrated module may be implemented in the form of hardware or in the form of a software functional module. It should be noted that in the present application, module division is an example and is merely a logical functional division. In actual implementation, other division methods may be used. Hereinafter, a communication device according to an embodiment of the present application will be described in detail with reference to FIGS. 8 to 10.

[0187] FIG. 8 is a diagram of the structure of a communication device according to one embodiment of the present application. As shown in FIG. 8, the communication device includes a processing unit (801) and a transceiver unit (802). The transceiver unit (802) can implement a corresponding communication function, and the processing unit (801) is configured to process data. For example, the transceiver unit (802) may also be referred to as a communication interface, a communication unit, etc.

[0188] In some embodiments of the present application, a communication device may be configured to perform an operation performed by a terminal device in the above-described method embodiment. In this case, the communication device may be a terminal device, or the communication device may be a component (e.g., a chip or a system) that may be placed within the terminal device. A transceiver unit (802) is configured to perform a receiving / transmitting-related operation of the terminal device in the above-described method embodiment. A processing unit (801) is configured to perform a processing-related operation of the terminal device in the above-described method embodiment.

[0189] For example, the transceiver unit (802) is configured to receive a first broadcast message from a first satellite. The processing unit (801) is configured to receive a second broadcast message from a second satellite through the transceiver unit (802) based on first display information.

[0190] For a detailed description of the first satellite, the first broadcast message, the first display information, the second satellite, the second broadcast message, etc., it may be understood to refer to the above-described method embodiments. Details are not described again herein.

[0191] In some other embodiments of the present application, a communication device may be configured to perform the operation performed by the first satellite in the aforementioned method embodiment. In this case, the communication device may be the first satellite, or the communication device may be a component (e.g., a chip or a system) that may be placed on the first satellite. A transceiver unit (802) is configured to perform the receiving / transmitting operation of the first satellite in the aforementioned method embodiment. A processing unit (801) is configured to perform the processing operation of the first satellite in the aforementioned method embodiment.

[0192] For example, the processing unit (801) is configured to acquire the ephemeris information of the second satellite. The transceiver unit (802) is configured to transmit the first broadcast message.

[0193] Optionally, the transceiver unit (802) is further configured to receive the first information.

[0194] For detailed descriptions of the first satellite, the first broadcast message, the first display information, the second satellite, the second broadcast message, the first information, etc., it is understood that reference is made to the above-described method embodiments. Details are not described again herein.

[0195] In another embodiment of the present application, a communication device may be configured to perform the operation performed by the second satellite in the previously mentioned method embodiment. In this case, the communication device may be the second satellite, or the communication device may be a component (e.g., a chip or a system) that may be placed on the second satellite. A transceiver unit (802) is configured to perform the receiving / transmitting operation of the second satellite in the previously mentioned method embodiments. A processing unit (801) is configured to perform the processing operation of the second satellite in the previously mentioned method embodiments.

[0196] For example, the transceiver unit (802) is configured to transmit the first information and the second broadcast message.

[0197] It will be understood that for detailed descriptions of the first information, the second broadcast message, etc., reference is made to the aforementioned method embodiments. Details are not described further herein.

[0198] Optionally, the communication device may further include a storage unit. The storage unit may be configured to store instructions and / or data. The processing unit (801) may read instructions and / or data from the storage unit so that the communication device implements the method embodiment described above.

[0199] It should be understood that the detailed description of the transceiver unit and processing unit described in the present embodiment of the application is merely illustrative. For specific functions, the steps performed by the transceiver unit and processing unit, etc., refer to the method embodiments described above. Details are not described again herein.

[0200] The foregoing describes a communication device in the embodiments of the present application. The following describes possible product forms of the communication device. It should be understood that any product of any form having the function of the communication device of FIG. 8 falls within the scope of protection of the embodiments of the present application. It should be further understood that the following description is merely an example and does not limit the product forms of the communication device in the embodiments of the present application.

[0201] In a possible embodiment, as illustrated in FIG. 8, the processing unit (801) may be one or more processors, and the transceiver unit (802) may be a transceiver. Alternatively, the transceiver unit (802) may be a transmitting unit and a receiving unit. The transmitting unit may be a transmitter, and the receiving unit may be a receiver. The transmitting unit and the receiving unit are integrated into a single device, for example, a transceiver. In the embodiments of the present application, the processor and the transceiver may be combined or similar. The method of connection between the processor and the transceiver is not limited in the present embodiments of the present application. In the process of performing the method described above, the process of transmitting information in the method described above may be understood as a process of outputting information by the processor. When outputting information, the processor outputs the information to the transceiver, so that the transceiver transmits the information. After the information is output by the processor, further processing may need to be performed before the information reaches the transceiver. Similarly, in the aforementioned method, the process of receiving information can be understood as a process of receiving input information by a processor. When the processor receives input information, the transceiver receives the information and inputs the information into the processor. Furthermore, after the transceiver receives the information, it may be necessary to perform other processing before the information is received by the processor.

[0202] As illustrated in FIG. 9, the communication device (90) includes one or more processors (920) and transceivers (910).

[0203] In some embodiments of the present application, the communication device may be configured to perform steps, functions, etc., performed by the terminal device in the above-described method embodiment.

[0204] For example, the transceiver (910) is configured to receive a first broadcast message from a first satellite. The processor (920) is configured to receive a second broadcast message from a second satellite through the transceiver (910) based on first display information.

[0205] In some other embodiments of the present application, the communication device may be configured to perform the steps, functions, etc., performed by the first satellite in the aforementioned method embodiment.

[0206] For example, the processor (920) obtains the ephemeris information of the second satellite. The transceiver (910) is configured to transmit the first broadcast message.

[0207] In another embodiment of the present application, the communication device may be configured to perform the steps, functions, etc., performed by the second satellite in the aforementioned method embodiment.

[0208] For example, the transceiver (910) is configured to transmit the first information and the second broadcast message.

[0209] It should be understood that the detailed descriptions of the transceivers and processors described in the embodiments of this application are merely examples. The aforementioned method embodiments refer to specific functions, steps performed by the transceivers and processors, etc. Details are not described herein.

[0210] In the embodiments mentioned above, the descriptions of the first satellite, the first broadcast message, the first display information, the second satellite, the second broadcast message, the first information, etc. refer to the descriptions in the method embodiments mentioned above. Details are not described again herein.

[0211] In an embodiment of the communication device illustrated in FIG. 9, the transceiver may include a receiver machine and a transmitter machine. The receiver machine is configured to perform a receiving function (or operation), and the transmitter machine is configured to perform a transmitting function (or operation). Furthermore, the transceiver is configured to communicate with another device / device through a transmitting medium.

[0212] Optionally, the communication device (90) may further include one or more memories (930) configured to store program instructions, data, etc. The memory (930) is coupled to the processor (920). In this embodiment of the invention, the connection may be an indirect coupling or communication connection between devices, units, or modules in an electrical form, a mechanical form, or other form, and is used for the exchange of information between devices, units, or modules. The processor (920) may operate in cooperation with the memory (930). The processor (920) may execute program instructions stored in the memory (930). Optionally, at least one of the one or more memories may be included in the processor.

[0213] The specific connection medium between the transceiver (910), the processor (920), and the memory (930) is not limited to this embodiment of the application. In this embodiment of the application, the memory (930), the processor (920), and the transceiver (910) are connected via the bus (940) of FIG. 9. The bus is indicated by a thick line in FIG. 9. The method of connection between other components is merely an example for illustrative purposes and is not limited thereto. The bus may be classified as an address bus, a data bus, a control bus, etc. For ease of explanation, only one thick line is used to represent the bus in FIG. 9, but this does not mean that there is only one bus or only one type of bus.

[0214] In this embodiment of the present application, the processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field-programmable gate array or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, etc., and may implement or perform the methods, steps, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor may be a microprocessor, any conventional processor, etc. The steps of the method with reference to the embodiments of the present application may be performed and completed directly by a hardware processor, or may be performed and completed using a combination of a hardware module such as a processor and a software module.

[0215] In the embodiments of the present application, memory may include, but is not limited to, non-volatile memory such as a hard disk drive (HDD) or solid-state drive (SSD), Random Access Memory (RAM), Erasable Programmable Read-Only Memory (EPROM), Read-Only Memory (ROM), Compact Disc Read-Only Memory (CD-ROM), etc. Memory is any storage medium that can be used to carry or store program code in the form of instructions or data structures and can be read and / or written by a computer (e.g., a communication device described in the present application). Of course, it is not necessarily limited thereto. Alternatively, the memory of the embodiments of the present application may be a circuit or any other device configured to implement a storage function and store program instructions and / or data.

[0216] For example, the processor (920) is configured to primarily process communication protocols and communication data, control the entire communication device, execute software programs, and process data of the software programs. The memory (930) is configured to primarily store software programs and data. The transceiver (910) may include a control circuit and an antenna. The control circuit is configured to primarily perform conversion between baseband signals and radio frequency signals and to process radio frequency signals. The antenna is configured to primarily transmit and receive radio frequency signals in the form of electromagnetic waves. Input / output devices, such as a touchscreen, display, or keyboard, are configured to primarily receive input data from the user and output data to the user.

[0217] After the communication device is powered on, the processor (920) reads the software program from the memory (930), interprets and executes the instructions of the software program, and processes the data of the software program. When data is to be transmitted wirelessly, the processor (920) performs baseband processing on the data to be transmitted and then outputs the baseband signal to the radio frequency circuit. The radio frequency circuit performs radio frequency processing on the baseband signal and then transmits the radio frequency signal in the form of electromagnetic waves through the antenna. When data is transmitted to the communication device, the radio frequency circuit receives the radio frequency signal through the antenna, converts the radio frequency signal into a baseband signal, outputs the baseband signal to the processor (920), and the processor (920) converts the baseband signal into data and processes the data.

[0218] In another embodiment, the radio frequency circuit and antenna may be positioned independently of the processor performing baseband processing. For example, in a distributed scenario, the radio frequency circuit and antenna may be positioned remotely, separate from the communication device.

[0219] It may be understood that the communication device illustrated in this embodiment of the present application may include more components, etc. than illustrated in FIG. 9. This is not limited to this embodiment of the present application. The method performed by the processor and transceiver is merely an example. Refer to the method described above for the specific steps performed by the processor and transceiver.

[0220] In another possible embodiment, as illustrated in FIG. 8, the processing unit (801) may be one or more logic circuits, and the transceiver unit (802) may be an input / output interface, or may be referred to as a communication interface, an interface circuit, an interface, etc. Alternatively, the transceiver unit (802) may be a transmitting unit and a receiving unit. The transmitting unit may be an output interface, and the receiving unit may be an input interface. The transmitting unit and the receiving unit are integrated into a single unit, for example, an input / output interface. As illustrated in FIG. 10, the communication device illustrated in FIG. 10 includes a logic circuit (1001) and an interface (1002). In other words, the processing unit (801) may be implemented through the logic circuit (1001), and the transceiver unit (802) may be implemented through the interface (1002). The logic circuit (1001) may be a chip, a processing circuit, an integrated circuit, a system-on-a-chip (SoC) chip, etc. The interface (1002) may be a communication interface, an input / output interface, a pin, or other. For example, FIG. 10 illustrates an example where the communication device is a chip. The chip includes a logic circuit (1001) and an interface (1002).

[0221] In this embodiment of the present application, the logic circuit and the interface may be coupled to each other. The specific method of connection between the logic circuit and the interface is not limited to this embodiment of the present application.

[0222] In some embodiments of the present application, the communication device may be configured to perform steps, functions, etc., performed by the terminal device in the method embodiment described above. For example, the interface (1002) is configured to input a first broadcast message. The logic circuit (1001) is configured to input a second broadcast message through the interface (1002) based on first display information.

[0223] In some other embodiments of the present application, the communication device may be configured to perform steps, functions, etc., performed by the first satellite in the method embodiment mentioned above. For example, the logic circuit (1001) is configured to acquire ephemeris information of the second satellite. The interface (1002) is configured to output a first broadcast message. Optionally, the interface (1002) is further configured to input the first information.

[0224] In another embodiment of the present application, the communication device may be configured to perform steps, functions, etc., performed by the second satellite in the aforementioned method embodiment. For example, the interface (1002) is configured to output the first information and the second broadcast message.

[0225] It will be understood that the detailed description of the logic circuit and interface described in the present embodiment of the application is merely illustrative. Specific functions, steps performed on the logic circuit and interface, etc., refer to the aforementioned method embodiments. Details are not described herein.

[0226] In the embodiments mentioned above, the descriptions of the first satellite, the first broadcast message, the first display information, the second satellite, the second broadcast message, the first information, etc. refer to the descriptions in the method embodiments mentioned above. Details are not described again herein.

[0227] It may be understood that the communication device described in the embodiments of this application may implement the method provided in the embodiments of this application in hardware form or in software form. This is not limited to the embodiments of this application.

[0228] One embodiment of the present application further provides a communication system. The communication system includes at least two of a terminal device, a first satellite, and a second satellite. The terminal device, the first satellite, and the second satellite are configured to perform a method according to any one of the previously mentioned embodiments.

[0229] Additionally, the present application further provides a computer program. The computer program is intended to implement the work and / or processing performed by the terminal device in the method provided in the present application.

[0230] The present application further provides a computer program. The computer program is intended to implement the operation and / or processing performed by the first satellite in the method provided in the present application.

[0231] The present application further provides a computer program. The computer program is intended to implement the operation and / or processing performed by the second satellite in the method provided in the present application.

[0232] The present application further provides a computer-readable storage medium. The computer-readable storage medium stores computer code. When the computer code is executed on a computer, the computer performs an operation and / or processing performed by a terminal device in the manner provided in the present application.

[0233] The present application further provides a computer-readable storage medium. The computer-readable storage medium stores computer code. When the computer code is executed on a computer, the computer performs the work and / or processing performed by the first satellite in the manner provided in the present application.

[0234] The present application further provides a computer-readable storage medium. The computer-readable storage medium stores computer code. When the computer code is executed on a computer, the computer performs the work and / or processing performed by the second satellite in the manner provided in the present application.

[0235] The present application further provides a computer program product. The computer program product includes computer code or a computer program. When the computer code or computer program is executed on a computer, an operation and / or processing performed by a terminal device in the method provided in the present application is performed.

[0236] The present application further provides a computer program product. The computer program product comprises computer code or a computer program. When the computer code or computer program is executed on a computer, the operation and / or processing performed by the first satellite in the method provided in the present application is performed.

[0237] The present application further provides a computer program product. The computer program product comprises computer code or a computer program. When the computer code or computer program is executed on a computer, the operation and / or processing performed by the second satellite in the method provided in the present application is performed.

[0238] It should be understood that in the various embodiments provided herein, the disclosed systems, devices, and methods may be implemented in different ways. For example, the described device embodiments are merely one example. For example, division into units is merely a logical functional division and may be different in actual implementation. For example, multiple units or components may be coupled or integrated into different systems, or some features may be ignored or not performed. Additionally, mutual coupling, direct coupling, or communication connections shown or described may be implemented through some interfaces, indirect coupling or communication connections between devices or units, or electrical connections, mechanical connections, or other forms of connections.

[0239] Units described as individual parts may or may not be physically separated, and parts indicated as units may or may not be physical units, may be located in one location, or may be distributed across multiple network units. Some or all of the units may be selected based on actual requirements for realizing the technical effects of the solutions provided in the embodiments of this application.

[0240] Additionally, in the embodiments of the present application, the functional units may be integrated into a single processing unit, each unit may exist physically independently, or two or more units may be integrated into a single unit. The integrated unit may be implemented in the form of hardware or in the form of a software functional unit.

[0241] Where an integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, the integrated unit may be stored within a computer-readable storage medium. Based on this understanding, the technical solutions of the present application, or parts contributing to the prior art, or all or part of the technical solutions may be implemented in the form of a software product. A computer software product is stored in a readable storage medium and includes a plurality of instructions for commanding a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in the embodiments of the present application. The aforementioned readable storage medium includes any medium capable of storing program code, such as a USB flash drive, a removable hard disk, read-only memory (ROM), random access memory (RAM), a magnetic disk, or an optical disk.

[0242] The foregoing descriptions are merely specific embodiments of the present application and are not intended to limit the scope of protection of the present application. Any modification or substitution readily apparent to those skilled in the art within the technical scope disclosed in the present application will be within the scope of protection of the present application. Therefore, the scope of protection of the present application corresponds to the scope of protection of the claims.

Claims

Claim 1 A communication method applied to a terminal device, comprising the step of receiving a first broadcast message from a first satellite—the first broadcast message includes first display information, and the first display information represents ephemeris information of a second satellite—and the step of receiving a second broadcast message from the second satellite based on the first display information. Claim 2 A communication method applied to a first satellite, comprising the step of acquiring ephemeris information of a second satellite and the step of transmitting a first broadcast message, wherein the first broadcast message includes first display information and the first display information represents the ephemeris information of the second satellite. Claim 3 A communication method according to paragraph 2, wherein the step of acquiring ephemeris information of the second satellite includes the step of receiving first information from the second satellite, wherein the first information includes ephemeris information of the second satellite. Claim 4 A communication method according to paragraph 3, wherein the first information further comprises at least one of the synchronization signal block (SSB) information of the second satellite, the coverage range of the second satellite, and the load status of the second satellite. Claim 5 A communication method according to any one of claims 1 to 4, wherein the first broadcast message further includes at least one of synchronization signal block (SSB) information of the second satellite, second display information, or third display information, wherein the second display information indicates the coverage range of the second satellite and the third display information indicates the load status of the second satellite. Claim 6 A communication method according to paragraph 5, wherein the second display information indicates the latitude and longitude corresponding to the coverage range of the second satellite. Claim 7 A communication method according to paragraph 5, wherein the second display information represents an identifier of a geographical area corresponding to the coverage range of the second satellite. Claim 8 A communication method according to claim 5, wherein the second display information represents a range of values ​​for an included angle formed between a beam emitted by the second satellite and a plane defined by the antenna panel of the second satellite. Claim 9 A communication method according to claim 5, wherein the third display information includes the number of users currently connected to the second satellite and / or the ratio of the number of users currently connected to the second satellite to the number of users allowed to be connected to the second satellite. Claim 10 A communication method according to claim 5, wherein the SSB information comprises at least one of the SSB center frequency of the second satellite, subcarrier spacing (SCS), system frame number (SFN) offset, SSB transmission periodicity, SSB time domain information, and half frame index. Claim 11 A communication method according to any one of claims 1 to 10, wherein the first display information includes the ephemeris information of the first satellite and the offset of the ephemeris of the second satellite with respect to the ephemeris of the first satellite. Claim 12 A communication method according to any one of claims 1 to 11, wherein the first broadcast message further includes fourth display information, and the fourth display information indicates that the first broadcast message further includes access information of the first satellite. Claim 13 A communication method according to any one of claims 1 to 12, wherein the first display information represents ephemeris information of a plurality of satellites, and the second satellite is one of the plurality of satellites that is closer to the terminal device, or the second satellite is one of the plurality of satellites that has a distance to the terminal device below a distance threshold value. Claim 14 A communication method according to any one of claims 1 to 12, wherein the first display information represents ephemeris information of a plurality of satellites, and the second satellite is one of the plurality of satellites having a longer service duration, or the second satellite is one of the plurality of satellites having a service duration greater than or equal to a time threshold. Claim 15 A communication method according to any one of claims 1 to 12, wherein the first display information represents ephemeris information of a plurality of satellites, and the second satellite is one of the plurality of satellites having a higher signal quality, or the second satellite is one of the plurality of satellites having a signal quality greater than or equal to a signal quality threshold. Claim 16 A communication method applied to a second satellite, comprising the step of transmitting first information to a first satellite—the first information including ephemeris information of the second satellite—and the step of transmitting a second broadcast message. Claim 17 A communication method according to claim 16, wherein the first information further comprises at least one of the synchronization signal block (SSB) information of the second satellite, the coverage range of the second satellite, and the load status of the second satellite. Claim 18 A communication device comprising a unit configured to perform a method according to any one of claims 1 through 17. Claim 19 A communication device comprising a processor and a memory, wherein the memory is configured to store instructions, and the processor is configured to execute instructions such that a method according to any one of claims 1 to 17 is performed. Claim 20 A communication device comprising a logic circuit and an interface, wherein the logic circuit is connected to the interface, the interface is configured to input and / or output a code instruction, and the logic circuit is configured to execute the code instruction such that a method according to any one of claims 1 to 17 is performed. Claim 21 A computer-readable storage medium, wherein the computer-readable storage medium is configured to store a computer program, and when the computer program is executed, a method according to any one of claims 1 to 17 is performed. Claim 22 A computer program, wherein when the computer program is executed, a method according to any one of claims 1 to 17 is performed. Claim 23 A communication system comprising at least two of a terminal device, a first satellite, and a second satellite, wherein the terminal device is configured to perform a method according to any one of claims 1 and 5 to 15, the first satellite is configured to perform a method according to any one of claims 2 to 15, and the second satellite is configured to perform a method according to claim 16 or 17.

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