Communication method and apparatus

Abstract

The present application discloses a communication method and apparatus. The method comprises: a terminal receiving first instruction information from a first cell corresponding to a first satellite, wherein the first instruction information is used for instructing the terminal to perform uplink synchronization with a second satellite without triggering a random access procedure; and after the terminal is within the coverage of the second satellite, if a first SSB and a second SSB are the same, performing uplink synchronization with the second satellite without triggering a random access procedure, wherein the first SSB is used for communication between the terminal and the first satellite, and the second SSB is used for communication between the terminal and the second satellite. By means of the method, after the terminal is within the coverage of the second satellite, the terminal can perform uplink synchronization with the second satellite without triggering a random access procedure, so that the efficiency of handover of the terminal between satellites can be improved.

Description

Communication method and device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on November 2, 2023, with application number 202311452706.7 and application name “A Communication Method and Device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of communication technology, and in particular to a communication method and device. Background Art

[0004] In non-terrestrial networks (NTNs), the satellites that can provide services to terminals may change as the satellites move. For example, satellite 1 provides services to terminals 1 through M, where M is a positive integer. As the satellites move, terminals 1 through M move from being within the coverage of satellite 1 to being within the coverage of satellite 2, requiring them to switch to satellite 2, which then provides services to terminals 1 through M. Consequently, a large number of terminals may need to switch from one satellite to another within a short period of time. Improving the efficiency of terminal handoffs across satellites requires further research.

[0005] Summary of the Invention

[0006] The present application provides a communication method and apparatus for improving the efficiency of a terminal during inter-satellite handover.

[0007] In a first aspect, an embodiment of the present application provides a communication method, which can be applied to a first device. The first device can be a terminal or a module in the terminal (such as a circuit, a chip, a chip system or a processor), and can also be a logical node, a logical module or software that can implement all or part of the terminal functions. The following description takes the first device as an example. The method may include: the terminal may receive first indication information from a first cell corresponding to a first satellite, and the first indication information is used to instruct the terminal to perform uplink synchronization with a second satellite without triggering a random access process. After the terminal is in the coverage area of ​​the second satellite, if the first SSB and the second SSB are the same, the terminal may perform uplink synchronization with the second satellite without triggering a random access process. The first SSB is used for communication between the terminal and the first satellite, and the second SSB is used for communication between the terminal and the second satellite.

[0008] Through this method, after the terminal is within the coverage of the second satellite, the terminal can perform uplink synchronization with the second satellite without triggering a random access procedure, thereby improving the efficiency of the terminal during inter-satellite handover. Furthermore, in this method, the terminal can only perform uplink synchronization with the second satellite without triggering a random access procedure when the first SSB and the second SSB are the same. In this way, the terminal can receive messages from the second satellite through the beam corresponding to the second SSB and successfully handover to the second satellite.

[0009] In one possible design, after the terminal is within the coverage of the second satellite, if the first SSB and the second SSB are identical and the signal quality of the second SSB is greater than a first threshold, the terminal may perform uplink synchronization with the second satellite without triggering a random access procedure. In this design, after the terminal is within the coverage of the second satellite, the terminal may perform uplink synchronization with the second satellite without triggering a random access procedure, thereby improving the efficiency of the terminal during inter-satellite handover. Furthermore, in this design, only when the first SSB and the second SSB are identical and the signal quality of the second SSB is greater than a first threshold does the terminal perform uplink synchronization with the second satellite without triggering a random access procedure, thereby enabling the terminal to receive messages from the second satellite and successfully handover to the second satellite.

[0010] In one possible design, the method further includes: after the terminal is within the coverage of the second satellite, if the first SSB and the second SSB are the same and the signal quality of the second SSB is less than or equal to a first threshold, the terminal performing uplink synchronization with the second satellite through a random access procedure. This design avoids or reduces the possibility that the terminal cannot receive messages from the second satellite when performing uplink synchronization with the second satellite without triggering the random access procedure. This allows the terminal to receive messages from the second satellite, thereby enabling the terminal to successfully switch to the second satellite.

[0011] In one possible design, the method further includes: the terminal may receive resource configuration information from the first cell or the second cell corresponding to the second satellite, where the resource configuration information is used to configure uplink resources. After the terminal is in the coverage of the second satellite, if the first SSB and the second SSB are the same and the signal quality of the second SSB is less than or equal to a first threshold, the terminal may send a message to the second cell through the uplink resources. In this design, when the first SSB and the second SSB are the same and the signal quality of the second SSB is less than or equal to the first threshold, the terminal may send a message to the second cell through the uplink resources configured by the resource configuration information, thereby reducing the delay in sending the message to the second cell.

[0012] In one possible design, the method further includes: after the terminal is within coverage of the second satellite, if the first SSB and the second SSB are different, the terminal may perform uplink synchronization with the second satellite through a random access procedure. In this design, when the first SSB and the second SSB are different, the terminal may perform uplink synchronization with the second satellite by triggering the random access procedure. This avoids the terminal being unable to receive messages from the second satellite when uplink synchronization with the second satellite is performed without triggering the random access procedure. The terminal may then receive messages from the second satellite and successfully switch to the second satellite.

[0013] In one possible design, the method further includes: the terminal may receive resource configuration information from the first cell or the second cell corresponding to the second satellite, where the resource configuration information is used to configure uplink resources. After the terminal is within the coverage of the second satellite, if the first SSB and the second SSB are different, the terminal may send a message to the second cell using the uplink resources. In this design, when the first SSB and the second SSB are different, the terminal may send the message to the second cell using the uplink resources configured by the resource configuration information, thereby reducing the latency of sending the message to the second cell.

[0014] In one possible design, the method further includes: the terminal may send information indicating the second SSB to the second cell using the uplink resources configured by the resource configuration information. In this way, the terminal may notify the second cell of the second SSB so that the second cell communicates with the terminal using the second SSB.

[0015] Optionally, the cell identifiers of the second cell corresponding to the second satellite and the first cell are the same or different.

[0016] In a second aspect, an embodiment of the present application provides a communication method, which can be applied to a first device. The first device can be a terminal or a module in the terminal (such as a circuit, chip, chip system or processor), and can also be a logical node, logic module or software that can implement all or part of the terminal functions. The following description takes the first device as an example of a terminal. The method may include: the terminal determines the difference between a first propagation delay and a second propagation delay. The first propagation delay is the propagation delay of the service link between the terminal and the first cell corresponding to the first satellite, and the second propagation delay is the propagation delay of the service link between the terminal and the second cell corresponding to the second satellite. The first satellite is the satellite that provides services to the terminal before the terminal is switched, and the second satellite is the satellite that provides services to the terminal after the terminal is switched. When the difference is greater than the second threshold, the terminal may send a second indication information, and the second indication information is used to indicate the reconfiguration of uplink resources for the terminal.

[0017] Using this method, if the difference between the first propagation delay and the second propagation delay is greater than a second threshold, the terminal can send a second indication message, which can be used to instruct the terminal to reconfigure uplink resources. The first propagation delay is related to the terminal and the first satellite serving the terminal before the handoff, while the second propagation delay is related to the terminal and the second satellite serving the terminal after the handoff. In this way, in inter-satellite handoff scenarios, the access network device can reconfigure uplink resources for the terminal, thereby avoiding or reducing data conflicts caused by the terminal's inter-satellite handoff.

[0018] In one possible design, the second indication information includes a difference value. In this way, the access network device can reconfigure uplink resources for the terminal based on the difference value, thereby avoiding data conflicts caused by the terminal performing cross-satellite switching.

[0019] In one possible design, the terminal can predict the difference between the first propagation delay and the second propagation delay at at least one of the following times: the time when the first satellite stops serving the terminal, the time when the second satellite starts serving the terminal, and the time when the terminal connects to the second satellite. This design reduces the terminal's computational workload and energy consumption.

[0020] In a third aspect, embodiments of the present application provide a communication method that can be applied to a second device. The second device can be an access network device or a module (e.g., a circuit, chip, chip system, or processor) in the access network device. It can also be a logical node, logic module, or software that can implement all or part of the functions of the access network device. The following description takes the second device as an access network device as an example. The method can include: the access network device receiving second indication information sent by the terminal when the difference between the first propagation delay and the second propagation delay is greater than a second threshold. The second indication information is used to instruct the reconfiguration of uplink resources for the terminal, where the first propagation delay is the propagation delay of the service link between the terminal and the first cell corresponding to the first satellite, and the second propagation delay is the propagation delay of the service link between the terminal and the second cell corresponding to the second satellite. The first satellite is the satellite that provided services to the terminal before the terminal was switched, and the second satellite is the satellite that provided services to the terminal after the terminal was switched. The access network device can reconfigure uplink resources for the terminal based on the second indication information.

[0021] In one possible design, the second indication information includes a difference.

[0022] In one possible design, the difference is the difference between the first propagation delay and the second propagation delay at at least one of the following moments: the moment when the first satellite stops providing services to the terminal, the moment when the second satellite starts providing services to the terminal, and the moment when the terminal accesses the second satellite.

[0023] In a fourth aspect, the present application provides a communication device, which may be a terminal or a module in a terminal (such as a circuit, chip, chip system or processor), or a logical node, logic module or software that can implement all or part of the terminal functions. The communication device has the function of implementing the first or second aspect above. For example, the communication device includes a module or unit or means corresponding to the operation involved in the first or second aspect above, and the module or unit or means may be implemented by software, or by hardware, or the corresponding software may be implemented by hardware.

[0024] In one possible design, the communication device includes a processing unit. Optionally, the communication device also includes an interface unit. The interface unit can be used to transmit and receive signals to enable communication between the communication device and other devices; the processing unit can be used to perform certain internal operations of the communication device. The functions performed by the processing unit and the interface unit can correspond to the operations described in the first or second aspect above.

[0025] In one possible design, the communication device includes a processor, which can be coupled to a memory. The memory can store the necessary computer programs or instructions for implementing the functions of the first or second aspect. The processor can execute the computer programs or instructions stored in the memory. When the computer programs or instructions are executed, the communication device implements the method of any possible design of the first or second aspect.

[0026] In one possible design, the communication device includes a processor and a memory. The memory may store the necessary computer programs or instructions for implementing the functions of the first or second aspect. The processor may execute the computer program or instructions stored in the memory. When the computer program or instructions are executed, the communication device implements the method of any possible design of the first or second aspect.

[0027] In one possible design, the communication device includes a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and execute the method in any possible design of the first aspect or the second aspect above.

[0028] In a fifth aspect, the present application provides a communication device, which may be an access network device or a module in the access network device (such as a circuit, chip, chip system or processor), and may also be a logical node, logic module or software that can implement all or part of the functions of the access network device. The communication device has the function of implementing the third aspect above. For example, the communication device includes a module or unit or means corresponding to the operation involved in the third aspect above. The module or unit or means may be implemented by software, or by hardware, or the corresponding software implementation may be executed by hardware.

[0029] In one possible design, the communication device includes a processing unit. Optionally, the communication device also includes an interface unit. The interface unit can be used to transmit and receive signals to enable communication between the communication device and other devices; the processing unit can be used to perform certain internal operations of the communication device. The functions performed by the processing unit and the interface unit can correspond to the operations described in the third aspect above.

[0030] In one possible design, the communication device includes a processor, which can be coupled to a memory. The memory can store the necessary computer programs or instructions for implementing the functions of the third aspect. The processor can execute the computer programs or instructions stored in the memory. When the computer programs or instructions are executed, the communication device implements the method of any possible design of the third aspect.

[0031] In one possible design, the communication device includes a processor and a memory, where the memory may store the necessary computer programs or instructions for implementing the functions of the third aspect. The processor may execute the computer program or instructions stored in the memory. When the computer program or instructions are executed, the communication device implements the method of any possible design of the third aspect.

[0032] In one possible design, the communication device includes a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and execute the method in any possible design of the third aspect above.

[0033] It can be understood that in the fourth aspect or the fifth aspect above, the processor can be implemented by hardware or by software. When implemented by hardware, the processor can be a logic circuit, an integrated circuit, etc.; when implemented by software, the processor can be a general-purpose processor, which is implemented by reading the software code stored in the memory. In addition, the above processors can be one or more, and the memories can be one or more. The memory can be integrated with the processor, or the memory and the processor can be set separately. In the specific implementation process, the memory can be integrated with the processor on the same chip, or can be set on different chips respectively. The embodiment of the present application does not limit the type of memory and the setting method of the memory and the processor.

[0034] In a sixth aspect, the present application provides a communication system.

[0035] In one possible design, the communication system may include the communication apparatus described in the fifth aspect and the communication apparatus described in the sixth aspect. The communication apparatus described in the fifth aspect is used to execute the communication method provided in the second aspect. For example, the communication system includes a terminal and an access network device; wherein the terminal is used to execute the communication method provided in the second aspect, and the access network device is used to execute the communication method provided in the third aspect.

[0036] In another possible design, the communication system may include the communication apparatus and access network equipment described in the fifth aspect. The communication apparatus described in the fifth aspect is configured to perform the communication method provided in the first aspect. For example, the communication system includes a terminal and an access network equipment; wherein the terminal is configured to perform the communication method provided in the first aspect, and the access network equipment is configured to perform the operations performed by the first satellite or the second satellite in the communication method provided in the first aspect.

[0037] In the seventh aspect, the present application provides a computer-readable storage medium, which stores a computer program or instruction. When the computer program or instruction is executed, the method in any possible design of any aspect of the first to third aspects above is implemented.

[0038] In an eighth aspect, the present application provides a computer program product, which includes a computer program code. When the computer program code is executed, the method in any possible design of any aspect from the first to the third aspects mentioned above is implemented.

[0039] In a ninth aspect, the present application provides a chip for reading a computer program stored in a memory to execute a method in any possible design of any one of the first to third aspects above.

[0040] The technical effects that can be achieved in any of the third to ninth aspects mentioned above can refer to the description of the technical effects that can be achieved in any possible design in any of the first to second aspects mentioned above, and the repetitions will not be discussed. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figures 1A to 1E are architecture diagrams of several communication systems provided in this application;

[0042] Figures 2A and 2B are schematic diagrams of an application scenario provided by this application;

[0043] FIG3 is a flow chart of a communication method provided by the present application;

[0044] FIG4 is a flow chart of another communication method provided by the present application;

[0045] FIG5 is a structural diagram of a communication device provided by the present application;

[0046] FIG6 is a structural diagram of another communication device provided in this application. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings in the embodiments of the present application. The technical solutions in the embodiments of the present application can be applied to various communication systems, such as universal mobile telecommunications system (UMTS), wireless local area network (WLAN), wireless fidelity (Wi-Fi) system, fourth generation (4G) mobile communication system (such as long term evolution (LTE) system), fifth generation (5G) mobile communication system (such as NR system), NTN communication system, and future evolved communication system (such as sixth generation (6G) mobile communication system). The communication system can be applied to machine to machine (M2M) network, machine type communication (MTC) or other networks.

[0048] This application will present various aspects, embodiments, or features in the context of systems that may include multiple devices, components, modules, etc. It should be understood and appreciated that each system may include additional devices, components, modules, etc., and / or may not include all of the devices, components, modules, etc. discussed in conjunction with the figures. Furthermore, combinations of these aspects may also be used.

[0049] The method provided in the embodiments of the present application can be applied to an NTN communication system. Figure 1A shows the architecture of an NTN communication system applicable to the embodiments of the present application. The communication system may include a terminal, a first access network device, and a second access network device. The communication link between the first access network device and the second access network device is a feedback link (or feeder link); the communication link between the second access network device and the terminal is a service link.

[0050] The first access network device may be a gateway station (also called a ground station, earth station, gateway, or gateway station) or a base station.

[0051] The second access network device may be a satellite (or satellite base station) or a high altitude platform station (HAPS), etc. The satellite may include at least one of the following: a geostationary earth orbit (GEO) satellite (or a geosynchronous orbit satellite) or a non-geostationary earth orbit (NGEO). The non-geostationary earth orbit satellite may include at least one of the following: a medium earth orbit (MEO) satellite or a low earth orbit (LEO) satellite. There is no limitation here.

[0052] In an embodiment of the present application, the communication mode of the second access network device may include a regenerative mode and a transparent mode (also referred to as a transparent mode). When the communication mode of the second access network device is the regenerative mode, the second access network device may serve as a base station for wireless communication. Exemplarily, the second access network device may include a next generation NodeB (gNB) or a distributed unit (DU). When the communication mode of the second access network device is the transparent mode, the second access network device may perform frequency conversion forwarding on the signal.

[0053] It should be understood that Figure 1A only shows one first access network device and one second access network device. In actual use, an architecture with multiple first access network devices and / or one second access network device may be adopted as needed. Each second access network device may provide services to one or more terminals, each second access network device may correspond to one or more first access network devices, and each first access network device may correspond to one or more second access network devices, which is not specifically limited in this application.

[0054] In this application, a terminal may also be referred to as user equipment (UE), access terminal, subscriber unit, user station, mobile station, mobile station (MS), remote station, remote terminal, mobile device, user terminal, terminal equipment, wireless communication device, user agent or user device.

[0055] A terminal can be a device that provides wireless communication capabilities, such as a handheld device or vehicle-mounted device with wireless connection capabilities. Currently, some examples of terminals include: mobile phones, satellite mobile terminals, cellular phones, smart phones, tablet computers, laptop computers, PDAs, mobile internet devices (MIDs), wearable devices (such as smart watches, smart bracelets, pedometers, smart glasses, etc.), vehicle-mounted devices (such as cars, bicycles, electric vehicles, airplanes, ships, trains, high-speed trains, etc.), satellite terminals, virtual reality (VR) devices, augmented reality (AR) devices, smart point of sale (POS) machines, customer-premises equipment (CPE), wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical surgery, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, and wireless terminals in smart homes. The present invention also includes wireless terminals (e.g., refrigerators, televisions, air conditioners, electric meters, etc.) in a home, intelligent robots, robotic arms, cellular phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDAs), handheld devices with wireless communication capabilities, computing devices or other processing devices connected to a wireless modem, flying devices (e.g., intelligent robots, hot air balloons, drones, airplanes), terminals in the 5th generation (5G) network, or terminals in a future-evolved public land mobile network (PLMN), etc., which are not limited in the embodiments of the present application. As an example and not a limitation, in the embodiments of the present application, the terminal may also be a mobile terminal (MT) in an integrated access and backhaul (IAB) node.When an IAB node faces its parent node, it can be regarded as a terminal. In this case, the IAB node plays the role of MT.

[0056] The embodiments of this application do not limit the device form factor of the terminal. The device used to implement the terminal's function can be a terminal; it can also be a device that supports the terminal in implementing the function, such as a chip system. The device can be installed in the terminal or used in conjunction with the terminal. In the embodiments of this application, the chip system can be composed of a chip or include a chip and other discrete components.

[0057] In this application, an access network device is a device that provides wireless communication functions for a terminal, and the terminal can communicate with a core network device through the access network device. As a node in a wireless access network, an access network device can also be called a base station, a radio access network (RAN) node (or device), or an access point (AP). A communication system may include multiple access network devices, which can be nodes of the same type or different types. In some scenarios, the roles of the access network device and the terminal are relative. For example, network element #A can be a helicopter or a drone, which can be configured as a mobile base station and access the RAN through network element #B. For those terminals that access the RAN through network element #A, network element #A is a base station; but for network element #B, network element #A is a terminal.

[0058] In one possible scenario, an access network device can be a base station, an evolved NodeB (eNodeB), a transmitting and receiving point (TRP), a transmitting point (TP), a gNB, a next-generation base station in a 6G mobile communication system, a base station in a future mobile communication system, a satellite, an access point (AP) in a WiFi system, an IAB node, a mobile switching center, or an access network device in an NTN communication system. That is, it can be deployed on a high-altitude platform or satellite, for example. The access network device can be a macro base station, a micro base station, an indoor station, a relay node, a donor node, or a radio controller in a cloud RAN (CRAN) scenario. The access network device can also be a device that functions as a base station in device-to-device (D2D) communication, Internet of Vehicles (IoV) communication, drone communication, or machine communication. Alternatively, the access network device can be a server, a wearable device, a vehicle, or an onboard device. For example, the access network device in vehicle-to-everything (V2X) technology can be a roadside unit (RSU).

[0059] In another possible scenario, multiple access network devices collaborate to assist the terminal in achieving wireless access, and different access network devices respectively implement part of the functions of the base station. For example, the access network device can be a centralized unit (CU), DU, CU-control plane (CP), CU-user plane (UP), or radio unit (RU). The CU and DU can be set separately, or can also be included in the same network element, such as a baseband unit (BBU). The RU can be included in a radio frequency device or radio frequency unit, such as a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH). It can be understood that the access network device can be a CU node, a DU node, or a device including a CU node and a DU node. In addition, the CU can be divided into an access network device in the access network RAN, or the CU can be divided into an access network device in the core network CN, which is not limited here.

[0060] In different systems, CU (or CU-CP and CU-UP), DU or RU may also have different names, but those skilled in the art can understand their meanings. For example, in the ORAN system, CU may also be called O-CU (Open CU), DU may also be called O-DU, CU-CP may also be called O-CU-CP, CU-UP may also be called O-CU-UP, and RU may also be called O-RU. For the convenience of description, this application uses CU, CU-CP, CU-UP, DU and RU as examples for description. Any unit of CU (or CU-CP, CU-UP), DU and RU in this application can be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

[0061] In the embodiments of the present application, the form of the access network device is not limited. The device used to implement the functions of the access network device can be the access network device; it can also be a device that supports the access network device to implement the functions, such as a chip system. The device can be installed in the access network device or used in conjunction with the access network device.

[0062] Access network equipment and terminals can be fixed or mobile. They can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; on water; and in the air on aircraft, balloons, and satellites. The embodiments of this application do not limit the application scenarios of access network equipment and terminals.

[0063] In this application, core network equipment refers to the network elements included in the core network part of a mobile communication system. For example, core network equipment refers to the network function (NF) network element and user plane function (UPF) network element included in the core network part. Core network equipment can connect terminals to different data networks and perform services such as billing, mobility management, session management, and user plane forwarding. Currently, some examples of NF network elements include: unified data management (UDM) network element, unified data repository (UDR) network element, network exposure function (NEF) network element, application function (AF) network element, policy control function (PCF) network element, access and mobility management function (AMF) network element, session management function (SMF) network element, network repository function (NRF) network element, etc.

[0064] The satellite communication system shown in this application may have multiple possible architectures, for example, any one of Architectures 1 to 5.

[0065] Architecture 1: Figure 1B illustrates a satellite communication system in transparent transmission mode applicable to embodiments of the present application. As shown in Figure 1B , a terminal and a ground base station can communicate via the Uu interface. The satellite and NTN gateway can be considered the RRUs of the ground base station, enabling transparent signal forwarding. The satellite supports functions such as radio frequency filtering, frequency conversion, and amplification; in other words, it can act as a Layer 1 relay, regenerating physical layer signals.

[0066] Architecture 2: Figure 1C illustrates a satellite communication system in regeneration mode applicable to embodiments of the present application. As shown in Figure 1C , a satellite performs some or all of the functions of an access network device and can be referred to as a satellite base station. The satellite can provide wireless access services and schedule wireless resources for terminal devices accessing the network through the satellite. There are no inter-satellite links (ISLs) between satellites.

[0067] Architecture 3: Figure 1D illustrates another satellite communication system in regeneration mode applicable to embodiments of the present application. As shown in Figure 1D , a satellite performs some or all of the functions of an access network device and can be referred to as a satellite base station. The satellite can provide wireless access services and schedule wireless resources for terminal devices accessing the network through the satellite. Satellites have an ISL (interconnected link) between them, for example, a link on the Xn interface, enabling communication between satellites.

[0068] Architecture 4: Figure 1E illustrates another satellite communication system in regenerative mode applicable to embodiments of the present application. As shown in Figure 1E , the satellite carries a DU, and the ground base station includes a CU. The NTN gateway can be considered the RRU of the ground base station, enabling transparent signal forwarding.

[0069] Architecture 5: The satellite is a base station with IAB function, and the terminal accesses the network through the satellite.

[0070] The following first explains the relevant terms involved in the embodiments of the present application. It should be noted that these explanations are intended to make the embodiments of the present application easier to understand and should not be regarded as limiting the scope of protection claimed by the present application.

[0071] (1) Random access process:

[0072] The random access process is initiated by the terminal to achieve uplink synchronization between the terminal and the access network device after the terminal and the access network device have achieved downlink synchronization. The random access process can be divided into contention-based random access process and non-contention-free random access process, which are described below.

[0073] The contention-based random access process can also be called a four-step random access process. In the contention-based random access process, the terminal can send a random access signal to the access network device, and the random access signal includes a preamble. The access network device can detect the preamble and estimate the propagation delay from the terminal to the access network device based on the preamble, thereby determining the timing advance (TA). The access network device sends a random access response (RAR) to the terminal. The RAR includes the TA, the time-frequency resource location of the uplink scheduling configured by the access network device for the terminal, etc. The terminal sends a radio resource control (RRC) request at the time-frequency resource location included in the RAR. The RRC request can also be called message 3 (Msg3). After receiving the RRC request, the access network device can send a contention resolution message to the terminal, thereby completing the random access.

[0074] The non-contention-based random access procedure, also known as the two-step random access procedure, allows the terminal to send a preamble according to the instructions of the preamble from the access network device. After receiving the preamble, the access network device sends a RAR to the terminal, completing the random access.

[0075] (2) Omitting the random access channel less (RACH-less) process:

[0076] During a handover, the source access network device can send the terminal the TA of the target cell corresponding to the target access network device. Once the terminal is within the coverage of the target cell, it can use this TA for uplink synchronization with the target access network device. This allows the terminal to communicate with the target access network device by omitting the random access procedure. This eliminates the need for the terminal to perform uplink synchronization with the target access network device through random access, thus saving signaling and reducing handover latency.

[0077] (3) Resources:

[0078] In this application, resources may include time domain resources and / or frequency domain resources. For example, time domain resources may include resources on a subframe, time slot, or symbol; frequency domain resources may include resources on a resource block (RB) or resource block group (RBG).

[0079] (4) Signal quality:

[0080] In the present application, signal quality may be signal strength. Parameters used to reflect or represent signal strength may include, but are not limited to, at least one of the following: reference signal receiving power (RSRP), reference signal receiving quality (RSRQ), or received signal strength indication (RSSI).

[0081] (5) Synchronization signal and physical broadcast channel (PBCH) block (SSB):

[0082] Currently, SSB may include synchronization signals and PBCH. Among them, the synchronization signal can be used by the terminal to perform downlink synchronization and obtain the identity (ID) of the cell, and the downlink synchronization may include frequency synchronization and time synchronization. PBCH can be used by the terminal to obtain information about the cell to which it is accessing. Exemplarily, SSB may include a primary synchronization signal (PSS), a secondary synchronization signal (SSS) and PBCH. Among them, PSS and SSS are both synchronization signals. PSS can be used to transmit the cell number, and SSS can be used to transmit the cell group number. The cell number and the cell group number together determine the multiple physical cell identities (PCIs) in the communication system. Once the terminal successfully searches for the PSS and SSS, it will know the PCI corresponding to the SSB. PBCH can be used to transmit the main information block (MIB). The MIB may include the system frame number and the subcarrier spacing for initial access, etc. The terminal can access the cell based on the MIB, etc.

[0083] (6) In the present application, the first SSB and the second SSB are the same, and have the same meaning as at least one of the following, and can be replaced with each other: the index of the first SSB and the index of the second SSB are the same, the beam corresponding to the first SSB is the same, the direction of the first SSB and the direction of the second SSB are the same, and the direction of the beam corresponding to the first SSB and the direction of the beam corresponding to the second SSB are the same. The first SSB and the second SSB are different, and have the same meaning as at least one of the following, and can be replaced with each other: the index of the first SSB and the index of the second SSB are different, the beam corresponding to the first SSB and the beam corresponding to the second SSB are different, the direction of the first SSB and the direction of the second SSB are different, and the direction of the beam corresponding to the first SSB and the direction of the beam corresponding to the second SSB are different. The terminal is within the coverage of the second satellite, which can be replaced by the terminal switching to the second satellite. Satellite transmission and satellite corresponding cell transmission can be replaced with satellite reception and satellite corresponding cell reception can be replaced with satellite reception. Performing uplink synchronization can be replaced by performing synchronization; downlink synchronization can be replaced by synchronization.

[0084] In an NTN, as satellites move, the satellites that can provide service to terminals may change. For example, satellite 1 provides service to terminals 1 through M, where M is a positive integer. As the satellites move, terminals 1 through M move from being within the coverage of satellite 1 to being within the coverage of satellite 2, requiring handoff to satellite 2, which then provides service to terminals 1 through M. Consequently, a large number of terminals may need to handoff from one satellite to another within a short period of time. Improving the efficiency of inter-satellite handoffs requires further research.

[0085] In some possible implementations, when performing an inter-satellite handover, a terminal may perform uplink synchronization with a target satellite by omitting a random access procedure, thereby communicating with the target satellite. For example, satellite 1 may broadcast time information 1, which may indicate one of the following: the time when satellite 1 stops serving area 1 (for example, area 1 may be the current coverage area of ​​satellite 1), the time when satellite 2 begins serving area 1, or the time when the terminal resynchronizes with satellite 2. Satellite 1 may also broadcast indication information 1, which indicates that the terminal may perform uplink synchronization with the target satellite by omitting a random access procedure. At or after the time indicated by time information 1, the terminal may synchronize with the target satellite by omitting a random access procedure.

[0086] The above method may cause at least one of the following problems:

[0087] Question 1: If the optimal beams of the terminal are inconsistent before and after the switch, the terminal may not be able to receive messages from the target satellite, and thus cannot successfully switch to the target satellite. For example, as shown in Figure 2A, the terminal wants to switch from satellite 1 to satellite 2. Within the coverage of satellite 1, the optimal beam of the terminal is the beam corresponding to SSB1. Within the coverage of satellite 2, the optimal beam of the terminal is the beam corresponding to SSB2. If there are both beams corresponding to SSB1 and beams corresponding to SSB2 within the coverage of satellite 2, the access network device does not know that the optimal beam of the terminal is the beam corresponding to SSB2, and may continue to send messages to the terminal through the beam corresponding to SSB1, for example, sending a physical downlink control channel (PDCCH) used to configure uplink resources. Since the beam is directional, the terminal may not be able to receive messages from satellite 2, and thus cannot switch to satellite 2.

[0088] Problem 2: If the terminal's serving access network equipment remains unchanged during inter-satellite handover, the terminal can achieve seamless transmission. However, data conflicts may occur during transmission. For example, a terminal switches from satellite 1 to satellite 2. The terminal communicates with satellite 1 via TA 1 and with satellite 2 via TA 2. Because the distance between the terminal and satellite 2 is greater than the distance between the terminal and satellite 1, TA 2 is greater than TA 1. Consequently, the first scheduling of the target cell corresponding to satellite 2 may occur simultaneously with the last scheduling of the source cell corresponding to satellite 1, resulting in data conflicts. For example, as shown in Figure 2B, subframe 3 sent by the terminal to the source cell and subframe 4 sent by the terminal to the target cell conflict in time, causing the data in subframe 3 sent by the terminal to the source cell to conflict with the data in subframe 4 sent by the terminal to the target cell.

[0089] In view of this, an embodiment of the present application provides a communication method. Figure 3 is a flow chart corresponding to the communication method provided by an embodiment of the present application. In the method shown in Figure 3, the first cell corresponding to the first satellite is taken as the source cell of the terminal, and the second cell corresponding to the second satellite is taken as the target cell of the terminal as an example; in other words, the first satellite is the satellite that provides services to the terminal before the terminal is switched, and the second satellite is the satellite that provides services to the terminal after the terminal is switched. Optionally, the cell identifiers (for example, PCI) of the first cell and the second cell are the same or different. As shown in Figure 3, the method includes:

[0090] S301: A first cell sends first indication information to a terminal; correspondingly, the terminal receives the first indication information from the first cell.

[0091] There are various times when the first cell sends the first indication information to the terminal. For example, when the terminal is about to leave the coverage of the first satellite, the first cell may send the first indication information to the terminal. For example, if the first satellite determines that the terminal will leave the coverage of the first satellite after a duration of 1, the first satellite may send the first indication information to the terminal. The basis for the first satellite to determine that the terminal will leave the coverage of the first satellite after a duration of 1 may include one or more of the first satellite's ephemeris, the terminal's moving speed, and the terminal's moving direction. Duration 1 may be pre-configured, for example, as specified by a protocol; it may be determined by the first satellite; or it may be determined by other devices (for example, core network devices) and then notified to the first satellite.

[0092] The first indication information may be used to instruct the terminal to perform uplink synchronization with the second satellite without triggering a random access procedure. In other words, the first indication information may be used to instruct the terminal to perform uplink synchronization with the second satellite without triggering a random access procedure. Not triggering a random access procedure, for example, means performing an omitted random access procedure.

[0093] There may be multiple ways in which the first indication information instructs the terminal to perform uplink synchronization with the second satellite without triggering a random access procedure, for example, way a1 or way a2.

[0094] Mode a1: The first indication information explicitly indicates that the terminal can perform uplink synchronization with the second satellite without triggering a random access procedure. For example, when the value of the first indication information is a first value (e.g., 0 or 1), the terminal is instructed to perform uplink synchronization with the second satellite without triggering a random access procedure.

[0095] Mode a2: The first indication information implicitly indicates that the terminal can synchronize uplink with the second satellite without triggering the random access process. For example, the first indication information includes the parameter N TA , N TA The value can be 0 or the N used by the terminal in the first cell. TA , the N used by the terminal in the first cell TA It can be used to determine the TA used by the terminal in the first cell. TA After that, the terminal can determine to perform uplink synchronization with the second satellite by not triggering the random access process. TA After that, the terminal can TA To calculate or adjust the initial TA used by the terminal in the second cell. TA , the terminal's location, the ephemeris of the first satellite, and the ephemeris of the second satellite, to determine an initial TA used by the terminal in the second cell. The ephemeris of the first satellite and the ephemeris of the second satellite may be obtained by the terminal from the first satellite.

[0096] The first indication information can be carried in a traditional message or in a new message; the first indication information can be carried in a message broadcast by the first cell or in a unicast message sent by the first cell to the terminal. This application does not impose any restrictions on this.

[0097] S302: After the terminal is in the coverage of the second satellite, if the first SSB and the second SSB are the same, the terminal may perform uplink synchronization with the second satellite without triggering the random access process; that is, the terminal may not trigger the random access process and perform uplink synchronization with the second satellite; or, in other words, the terminal performs uplink synchronization with the second satellite but does not trigger the random access process.

[0098] Among them, the first SSB is used for communication between the terminal and the first satellite, and the second SSB is used for communication between the terminal and the second satellite; in other words, the terminal can use the first SSB to communicate with the first satellite, and the terminal can use the second SSB to communicate with the second satellite.

[0099] In some possible implementations, after the terminal is within coverage of the second satellite, the terminal may determine the second SSB. If the first SSB and the second SSB are the same, the terminal may perform uplink synchronization with the second satellite without triggering a random access procedure.

[0100] Optionally, the timing at which the terminal determines the second SSB may be determined based on indication information 2 from the first cell. In other words, the first cell sends indication information 2 to the terminal, and indication information 2 may be used to determine the timing at which the terminal determines the second SSB. Indication information 2 may be carried in a traditional message or in a new message. Indication information 2 may be carried in the same message as the first indication information or in a different message. Indication information 2 may be a message broadcast by the first cell or a unicast message sent by the first cell to the terminal.

[0101] In some possible embodiments, the indication information 2 indicates that the terminal needs to resynchronize. In this way, after receiving the indication information 2, the terminal can determine the second SSB.

[0102] In some other possible embodiments, the indication information 2 includes time information 2, and the time information 2 may indicate a moment 1, which is related to the timing when the terminal determines the second SSB. The moment 1 may be one of the following: the moment when the first satellite stops serving area 2 (for example, area 2 may be the current coverage area of ​​the first satellite) (which may be called t-Service), the moment when the second satellite starts serving area 2 (which may be called t-Start), or the moment when the terminal re-synchronizes uplink with the second satellite. The moment when the second satellite starts serving area 2 may be represented by the time interval (which may be called t-gap) between the moment when the second satellite starts serving area 2 and the moment when the first satellite stops serving area 2. The time interval may be an integer, a negative number, or 0.

[0103] For example, time 1 is the time when the first satellite stops serving area 2. The terminal may determine the second SSB at time 1, duration 2 before time 1, or duration 3 after time 1. Duration 2 and duration 3 may be preconfigured, for example, as specified by a protocol; may be determined by the terminal; or may be determined by another device (e.g., the first satellite or the second satellite) and then notified to the terminal.

[0104] For another example, time 1 is the time when the second satellite begins serving area 2. The terminal may determine the second SSB at time 1, or at time duration 4 before time 1, or at time duration 5 after time 1. Time duration 4 and time duration 5 may be preconfigured, for example, as specified by a protocol; may be determined by the terminal; or may be determined by another device (e.g., the first satellite or the second satellite) and then notified to the terminal.

[0105] For another example, time 1 is the time when the terminal resynchronizes with the second satellite. The terminal may determine the second SSB at time 1 or time duration 6 after time 1. Time duration 6 may be preconfigured, for example, specified by a protocol; may be determined by the terminal; or may be determined by another device (for example, the first satellite or the second satellite) and then notified to the terminal.

[0106] There are multiple ways for the terminal to determine the second SSB, for example, method b1, method b2 or method b3.

[0107] Method b1: After the terminal is within the coverage of the second satellite, the terminal determines whether it can receive the first SSB from the second cell. If the terminal can receive the first SSB from the second cell, the terminal may determine the first SSB as the second SSB; that is, the first SSB and the second SSB are the same, and the terminal may use the first SSB to communicate with the second satellite. If the terminal cannot receive the first SSB from the second cell, the terminal may determine the SSB with the best signal quality from the second cell, or any SSB from the second cell with a signal quality greater than threshold 1, as the second SSB.

[0108] Mode b2: After the terminal is within the coverage of the second satellite, the terminal determines whether it can receive the first SSB from the second cell. If the terminal can receive the first SSB from the second cell and the signal quality of the first SSB is greater than a first signal quality threshold, the terminal may determine the first SSB as the second SSB; that is, the first SSB and the second SSB are the same, and the terminal may use the first SSB to communicate with the second satellite. If the terminal can receive the first SSB from the second cell and the signal quality of the first SSB is less than or equal to the first signal quality threshold; or if the terminal cannot receive the first SSB from the second cell, the terminal may determine the SSB with the best signal quality from the second cell or any SSB from the second cell with a signal quality greater than threshold 1 as the second SSB. The first signal quality threshold may be pre-configured, for example, specified by a protocol; may be determined by the terminal; or may be configured for the terminal by other equipment (for example, the first satellite or the second satellite).

[0109] Optionally, in method b2, greater than can be replaced by greater than or equal to, and less than or equal to can be replaced by less than.

[0110] Method b3: After the terminal is in the coverage of the second satellite, the terminal can determine the SSB with the best signal quality from the second cell or any SSB with a signal quality greater than threshold 1 from the second cell as the second SSB. In other words, the second SSB is the SSB with the best signal quality from the second cell or the SSB with a signal quality greater than threshold 1.

[0111] In modes b1 to b3, threshold 1 may be pre-configured, for example, specified by a protocol; may be determined by the terminal; or may be configured for the terminal by other devices (for example, the first satellite or the second satellite).

[0112] As previously described, in S302, the terminal may perform uplink synchronization with the second satellite by not triggering a random access procedure. Exemplarily, the terminal may perform uplink synchronization with the second satellite by omitting the random access procedure; in other words, the terminal may perform the omission of the random access procedure, thereby achieving uplink synchronization between the terminal and the second satellite. For details on omitting the random access procedure, refer to the explanation of omitting the random access procedure in the Glossary section above. However, the source access network device is replaced by the first satellite or first cell, and the target access network device is replaced by the second satellite or second cell. This description is omitted here.

[0113] In some possible ways, in S302, the terminal performs uplink synchronization with the second satellite by not triggering the random access process, which may include: the terminal sets the corresponding parameter N of the second cell TA The value of or the parameter N corresponding to the TA group where the second cell is locatedTA The value is set to the parameter N received by the terminal in the first cell TA The value of parameter N received by the terminal in the first cell TA It can be the parameter N included in the first indication information TA , or it may be a parameter N sent by the first cell to the terminal through information other than the first indication information TA .

[0114] Using the method shown in Figure 3, once a terminal is within the coverage of a second satellite, it can perform uplink synchronization with the second satellite without triggering a random access procedure, thereby improving the efficiency of inter-satellite handover. Furthermore, in this method, the terminal can only perform uplink synchronization with the second satellite without triggering a random access procedure when the first and second SSBs are identical. This allows the terminal to receive messages from the second satellite via the beam corresponding to the second SSB and successfully handover to the second satellite, thus resolving Problem 1 above.

[0115] In some possible embodiments, the method shown in FIG3 further includes step A1:

[0116] Step A1: After the terminal is within the coverage of the second satellite, if the first SSB and the second SSB are different, the terminal performs uplink synchronization with the second satellite through a random access procedure. In other words, the terminal triggers or executes a random access procedure to achieve uplink synchronization with the second satellite. The details of this random access procedure can be found in the explanation of terminology, except that the access network device is replaced with the second satellite or second cell. This description is omitted here.

[0117] In some possible implementations, after the terminal is within the coverage of the second satellite, the terminal may determine the second SSB. If the first SSB and the second SSB are different, the terminal performs uplink synchronization with the second satellite through a random access procedure. The timing and manner in which the terminal determines the second SSB can be found in the description of the timing and manner in which the terminal determines the second SSB in S302, and will not be repeated here.

[0118] In this manner, when the first SSB and the second SSB are different, the terminal can perform uplink synchronization with the second satellite by triggering a random access process, thereby avoiding the situation where the terminal is unable to receive messages from the second satellite when uplink synchronization with the second satellite is performed without triggering the random access process, and further enabling the terminal to receive messages from the second satellite and successfully switch to the second satellite.

[0119] In some other possible embodiments, the method shown in FIG3 further includes steps B1 and B2:

[0120] Step B1: The first cell or the second cell sends resource configuration information to the terminal; correspondingly, the terminal receives the resource configuration information from the first cell or the second cell.

[0121] The resource configuration information is used to configure uplink resources. The uplink resources can be used for the terminal to send messages to the second satellite after it is in the coverage of the second satellite. Exemplarily, the resource configuration information may include indication information of the uplink resources. For example, the resource information may include: frequency domain offset information and time domain information. The frequency domain offset information indicates the frequency offset between the uplink resource and the center frequency point, and the time domain information indicates the time domain position of the uplink resource (such as the starting frame and / or starting symbol). The resource configuration information can be carried in a traditional message or in a new message. The resource configuration information can be carried in the same message as the first indication information, or in a different message.

[0122] In some possible implementations, when step B1 includes the first cell sending resource configuration information to the terminal, the first cell may send the resource configuration information to the terminal when the terminal is about to leave the coverage of the first satellite. For details about the terminal about to leave the coverage of the first satellite, refer to the description of the terminal about to leave the coverage of the first satellite in S301, and will not be repeated here.

[0123] Optionally, to enable the second cell to receive messages from the terminal using the uplink resource, the second cell may learn that the uplink resource is used for the terminal to send messages to the second cell after it is within the coverage of the second satellite. In some examples, after configuring the uplink resource for the terminal, the first cell may notify the second cell that the uplink resource is used for the terminal to send messages to the second cell after it is within the coverage of the second satellite. In other examples, the uplink resource is a resource configured by the second cell for the terminal to send messages. After configuring the uplink resource, the second cell notifies the first cell of the uplink resource, and the first cell may then execute step B1.

[0124] In other possible embodiments, when step B1 includes the second cell sending resource configuration information to the terminal, the second cell may send the resource configuration information to the terminal after the terminal is within the coverage of the second satellite. Exemplarily, the second cell may broadcast the resource configuration information, so that the terminal can receive the resource configuration information from the second cell after the terminal is within the coverage of the second satellite.

[0125] Step B2: After the terminal is within the coverage of the second satellite, if the first SSB and the second SSB are different, the terminal sends a message to the second cell using the uplink resources configured by the resource configuration information. Exemplarily, after the terminal is within the coverage of the second satellite, if the first SSB and the second SSB are different, the terminal sends a message including data and / or control information to the second cell using the uplink resources.

[0126] Optionally, the terminal may send information indicating the second SSB to the second cell through the uplink resources (for example, initial uplink resources) configured by the resource configuration information. In this way, the terminal may notify the second cell of the second SSB so that the second cell uses the second SSB to communicate with the terminal. In some examples, the information indicating the second SSB may explicitly indicate the second SSB, for example, the information indicating the second SSB is the index of the second SSB. In other examples, the information indicating the second SSB may implicitly indicate the second SSB, for example, the information indicating the second SSB may be information that corresponds to the second SSB. The information indicating the second SSB may be carried in a traditional message or in a new message, and this application does not impose any restrictions on this.

[0127] In this manner, when the first SSB and the second SSB are different, the terminal can send a message to the second cell through the uplink resources configured by the resource configuration information, thereby reducing the delay in sending the message to the second cell.

[0128] In some possible approaches, S302 may be replaced by step C1.

[0129] Step C1: After the terminal is within the coverage of the second satellite, if the first SSB and the second SSB are the same and the signal quality of the second SSB is greater than a first threshold, the terminal may perform uplink synchronization with the second satellite without triggering a random access procedure. For details of the terminal performing uplink synchronization with the second satellite without triggering a random access procedure, please refer to the description of the terminal performing uplink synchronization with the second satellite without triggering a random access procedure in S302; for the timing and manner in which the terminal determines the second SSB, please refer to the description of the timing and manner in which the terminal determines the second SSB in S302, which will not be repeated here. The first threshold may be pre-configured, for example, specified by a protocol; may be determined by the terminal; or may be configured for the terminal by other devices (e.g., the first satellite or the second satellite).

[0130] Optionally, the greater than in step C1 can be replaced by greater than or equal to.

[0131] In this approach, after the terminal is within the coverage of the second satellite, it can perform uplink synchronization with the second satellite without triggering a random access procedure, thereby improving the efficiency of the terminal's inter-satellite handover. Furthermore, in this approach, only when the first and second SSBs are the same and the signal quality of the second SSB is greater than a first threshold does the terminal perform uplink synchronization with the second satellite without triggering a random access procedure, thereby enabling the terminal to receive messages from the second satellite and successfully handover to the second satellite.

[0132] In some implementations, the method shown in FIG3 further includes step D1:

[0133] Step D1: After the terminal is in the coverage of the second satellite, if the first SSB and the second SSB are the same and the signal quality of the second SSB is less than or equal to the first threshold, the terminal can perform uplink synchronization with the second satellite through a random access process.

[0134] Among them, for the specific content of the terminal performing uplink synchronization with the second satellite through the random access process, reference may be made to the description of the terminal performing uplink synchronization with the second satellite through the random access process in step A1; for the specific content of the first threshold, reference may be made to the description of the first threshold in step C1, which will not be repeated here.

[0135] Optionally, the less than or equal to in step D1 can be replaced by less than.

[0136] In this implementation, when the first SSB and the second SSB are the same and the signal quality of the second SSB is less than or equal to the first threshold, the terminal can perform uplink synchronization with the second satellite by triggering a random access process, thereby avoiding or reducing the terminal's inability to receive messages from the second satellite when uplink synchronization with the second satellite is performed without triggering the random access process, and then enabling the terminal to receive messages from the second satellite, so that the terminal can successfully switch to the second satellite.

[0137] In some other implementations, the method shown in FIG3 further includes steps E1 to E2:

[0138] Step E1: The first cell or the second cell sends resource configuration information to the terminal; correspondingly, the terminal receives the resource configuration information from the first cell or the second cell.

[0139] The specific content of step E1 can be referred to step B1 and will not be repeated here.

[0140] Step E2: After the terminal is within the coverage of the second satellite, if the first SSB and the second SSB are the same, and the signal quality of the second SSB is less than or equal to the first threshold, the terminal may send a message to the second cell using the uplink resources configured by the resource configuration information. Exemplarily, after the terminal is within the coverage of the second satellite, if the first SSB and the second SSB are the same, and the signal quality of the second SSB is less than or equal to the first threshold, the terminal may send a message including data and / or control information to the second cell using the uplink resources.

[0141] Optionally, the terminal may send information indicating the second SSB to the second cell through the uplink resources configured by the resource configuration information (e.g., initial uplink resources). In this way, the terminal may notify the second cell of the second SSB so that the second cell communicates with the terminal using the second SSB. For the specific content of the information indicating the second SSB, refer to the description of the information indicating the second SSB in step B2, which will not be repeated here.

[0142] In this manner, when the first SSB and the second SSB are the same and the signal quality of the second SSB is less than or equal to the first threshold, the terminal can send a message to the second cell through the uplink resources configured by the resource configuration information, thereby reducing the delay in sending the message to the second cell.

[0143] In some possible embodiments, the method shown in FIG3 further includes steps S303 to S304:

[0144] S303: The first cell sends indication information 2 to the terminal; correspondingly, the terminal receives indication information 2 from the first cell.

[0145] The indication information 2 may be used to determine the timing for the terminal to perform downlink synchronization with the second cell. Specific contents of the indication information 2 may refer to the description of the indication information 2 in S302, and the repeated parts will not be repeated here.

[0146] S304: The terminal and the second cell perform downlink synchronization.

[0147] In some possible manners, the indication information 2 indicates that the terminal needs to resynchronize. In this way, after receiving the indication information 2, the terminal may start to switch to the second satellite and perform downlink synchronization with the second satellite.

[0148] In other possible embodiments, indication information 2 includes time information 2, which may indicate time 1. Time 1 is related to the timing of downlink synchronization between the terminal and the second cell. The terminal may perform downlink synchronization with the second cell based on time 1. For details about time 1, refer to the description of time 1 in S302 and are not repeated here.

[0149] For example, time 1 is the time when the first satellite stops serving area 2. The terminal may begin handover to the second satellite and downlink synchronization with the second satellite at time 1, or at time 7 before time 1, or at time 8 after time 1. Time 7 and time 8 may be preconfigured, for example, as specified by a protocol; may be determined by the terminal; or may be determined by another device (e.g., the first satellite or the second satellite) and notified to the terminal.

[0150] For example, time 1 is the time when the second satellite begins serving area 2. The terminal may begin handover to the second satellite and downlink synchronization with the second satellite at time 1, or at time 9 before time 1, or at time 10 after time 1. Time 9 and time 10 may be preconfigured, for example, as specified by a protocol; may be determined by the terminal; or may be determined by another device (e.g., the first satellite or the second satellite) and then notified to the terminal.

[0151] For another example, if time 1 is the time when the terminal resynchronizes with the second satellite, the terminal may start switching to the second satellite and downlink synchronization with the second satellite at time 1 or at a time duration 11 after time 1. The time duration 11 may be preconfigured, for example, as specified by a protocol; may be determined by the terminal; or may be determined by another device (for example, the first satellite or the second satellite) and then notified to the terminal.

[0152] This application does not limit the specific process of downlink synchronization, nor does it limit the execution order of S304 and the terminal determining the second SSB.

[0153] In some possible embodiments, the method shown in FIG3 further includes step G1:

[0154] Step G1: The second cell transmits a PDCCH via the beam corresponding to the second SSB. Accordingly, the terminal monitors the PDCCH from the second cell via the beam corresponding to the second SSB. This PDCCH can be used to schedule uplink transmission resources for the terminal. The terminal can then send a message to the second cell based on the uplink transmission resources.

[0155] Optionally, step G1 may occur after the terminal and the second cell perform uplink synchronization. For example, step G1 may occur after S302, step A1, step C1, or step D1.

[0156] An embodiment of the present application provides another communication method. Figure 4 is a flow chart corresponding to the communication method provided by an embodiment of the present application. In the method shown in Figure 4, the first cell corresponding to the first satellite is taken as the source cell of the terminal, and the second cell corresponding to the second satellite is taken as the target cell of the terminal. In other words, the first satellite is the satellite that provides services to the terminal before the terminal switches, and the second satellite is the satellite that provides services to the terminal after the terminal switches. Optionally, the cell identifiers (for example, PCI) of the first cell and the second cell are the same or different. As shown in Figure 4, the method includes:

[0157] S401: The terminal determines a difference between a first propagation delay and a second propagation delay.

[0158] The first propagation delay and the second propagation delay may have multiple possible modes, for example, mode c1 or mode c2.

[0159] Method c1: The first propagation delay is the propagation delay of the service link between the terminal and the first cell, and the second propagation delay is the propagation delay of the service link between the terminal and the second cell. For example, if the propagation delay of the service link between the terminal and the first cell is T1, and the propagation delay of the service link between the terminal and the second cell is T2, then the first propagation delay is T1, the second propagation delay is T2, and the difference between the first and second propagation delays can be T2-T1.

[0160] Method c2: The first propagation delay is the sum of the propagation delay of the service link between the terminal and the first cell, and the propagation delay of the link between the first satellite and the first reference point. The second propagation delay is the sum of the propagation delay of the service link between the terminal and the second cell corresponding to the second satellite, and the propagation delay of the link between the second satellite and the second reference point. The first reference point is a point between the first satellite and the ground station (or base station). The second reference point is a point between the second satellite and the ground station (or base station).

[0161] Exemplarily, the first reference point and the second reference point are ground stations or base stations. The first propagation delay may be the sum of the propagation delay of the service link between the terminal and the first cell and the propagation delay of the feedback link between the first satellite and the ground station. The second propagation delay may be the sum of the propagation delay of the service link between the terminal and the second cell and the propagation delay of the feedback link between the second satellite and the ground station. For example, if the propagation delay of the service link between the terminal and the first cell is T1, the propagation delay of the feedback link between the first satellite and the ground station is T3, the propagation delay of the service link between the terminal and the second cell is T2, and the propagation delay of the feedback link between the second satellite and the ground station is T4, then the first propagation delay is T1+T3, the second propagation delay is T2+T4, and the difference between the first propagation delay and the second propagation delay may be T2+T4-T1-T3.

[0162] There may be various times at which the difference between the first propagation delay and the second propagation delay corresponds.

[0163] In some possible ways, the terminal may determine the difference between the first propagation delay and the second propagation delay at the current moment; in other words, the terminal may determine the difference between the first propagation delay and the second propagation delay in real time. In some examples, the terminal may periodically determine the difference between the first propagation delay and the second propagation delay. The determination period may be pre-configured, for example, as specified by a protocol; may be determined by the terminal; or may be determined by other devices (for example, the first satellite or the second satellite) and then notified to the terminal. In other examples, the terminal may determine the difference between the first propagation delay and the second propagation delay based on an event trigger. For example, after receiving indication 1 from the first cell or the second cell, the terminal determines the difference between the first propagation delay and the second propagation delay at the current moment, where indication 1 is used to instruct the terminal to determine the difference between the first propagation delay and the second propagation delay.

[0164] In other possible approaches, the terminal can predict the difference between the first propagation delay and the second propagation delay at at least one of the following times: the time when the first satellite stops serving the terminal, the time when the second satellite starts serving the terminal, and the time when the terminal connects to the second satellite. In other words, the difference is the difference between the first propagation delay and the second propagation delay at at least one of the following times: the time when the first satellite stops serving the terminal, the time when the second satellite starts serving the terminal, and the time when the terminal connects to the second satellite. This approach can reduce the terminal's computational workload and energy consumption.

[0165] Optionally, the terminal may determine the first propagation delay and the second propagation delay according to the NTN parameters and the location of the terminal. There are multiple determination methods, for example, method d1 or method d2.

[0166] Method d1: The first propagation delay and the second propagation delay are implemented using method c1. The NTN parameters may include the ephemeris of the first satellite and the ephemeris of the second satellite. The terminal may determine the first propagation delay based on the ephemeris of the first satellite and the terminal's position; and determine the second propagation delay based on the ephemeris of the second satellite and the terminal's position. The terminal's position may be its real-time position or a predicted position at at least one of the following times: the time when the first satellite stops providing service to the terminal, the time when the second satellite begins providing service to the terminal, or the time when the terminal accesses the second satellite.

[0167] For example, if the terminal determines that the distance between the first satellite and the terminal is d1 based on the ephemeris of the first satellite and the terminal's position, the first propagation delay T1 is d1 / c, where c is the speed of light. If the terminal determines that the distance between the second satellite and the terminal is d2 based on the ephemeris of the second satellite and the terminal's position, the second propagation delay T2 is d2 / c, where c is the speed of light.

[0168] The following describes how a terminal obtains NTN parameters. These NTN parameters may be obtained from the first cell and / or the second cell. For example, the terminal obtains NTN parameters including the ephemeris of the first satellite and the ephemeris of the second satellite from the first cell or the second cell. In another example, the terminal obtains NTN parameters including the ephemeris of the first satellite from the first cell and NTN parameters including the ephemeris of the second satellite from the second cell.

[0169] Optionally, the NTN parameter may be carried in a broadcast message sent by the first cell and / or the second cell, or may be carried in a unicast message sent by the first cell and / or the second cell to the terminal.

[0170] Method d2: The first propagation delay and the second propagation delay are implemented as in method c2. The terminal can determine the first propagation delay and the second propagation delay based on NTN parameters, the terminal's location, and the locations of the first reference point and the second reference point. The NTN parameters may include the ephemeris of the first satellite and the ephemeris of the second satellite.

[0171] Optionally, the terminal may determine the first propagation delay based on the ephemeris of the first satellite, the position of the terminal, and the position of the first reference point; and determine the second propagation delay based on the ephemeris of the second satellite, the position of the terminal, and the position of the second reference point. The specific content of the terminal's position can be referred to the description of the terminal's position in method d1 and will not be repeated here. For example, if the terminal determines that the distance between the first satellite and the terminal is d1 based on the ephemeris of the first satellite and the position of the terminal, and determines that the distance between the first satellite and the first reference point is d3 based on the ephemeris of the first satellite and the position of the first reference point, then the first propagation delay is (d1+d3) / c, where c is the speed of light. If the terminal determines that the distance between the second satellite and the terminal is d2 based on the ephemeris of the second satellite and the position of the terminal, and determines that the distance between the second satellite and the second reference point is d4 based on the ephemeris of the second satellite and the position of the second reference point, then the second propagation delay is (d2+d4) / c, where c is the speed of light.

[0172] For the specific content of the terminal obtaining the NTN parameters, please refer to the description of the method for the terminal to obtain the NTN parameters in method d1, which will not be repeated here. For the method for the terminal to obtain the position of the first reference point and the position of the second reference point, please refer to the description of the method for the terminal to obtain the NTN parameters in method d1, except that the NTN parameters are replaced by the position of the first reference point and the position of the second reference point, which will not be repeated here.

[0173] S402: When the difference between the first propagation delay and the second propagation delay is greater than a second threshold, the terminal sends second indication information; correspondingly, the access network device receives the second indication information.

[0174] The access network device may be the first satellite or a base station located on the ground. The second threshold may be pre-configured, for example, as specified by a protocol; may be determined by the terminal; or may be determined by another device (for example, the access network device) and then notified to the terminal.

[0175] The second indication information may be used to instruct the reconfiguration of uplink resources for the terminal. The second indication information may instruct the reconfiguration of uplink resources for the terminal in multiple ways, for example, way e1 or way e2.

[0176] Mode e1: The second indication information explicitly indicates that uplink resources should be reconfigured for the terminal. For example, the second indication information is a request for reconfiguration of uplink resources for the terminal. Thus, after receiving the second indication information, the access network device may determine that uplink resources should be reconfigured for the terminal.

[0177] Method e2: The second indication information may implicitly indicate the reconfiguration of uplink resources for the terminal. For example, the second indication information may include the difference between the first propagation delay and the second propagation delay. Thus, upon receiving the second indication information, the access network device may determine that uplink resources need to be reconfigured for the terminal. Furthermore, because the second indication information includes the difference between the first propagation delay and the second propagation delay, the access network device may also reconfigure uplink resources for the terminal based on this difference, effectively avoiding data conflicts.

[0178] Optionally, in S402, “greater than” may be replaced by “greater than or equal to”.

[0179] In some possible embodiments, S402 may be replaced by: when the absolute value of the difference between the first propagation delay and the second propagation delay is greater than a second threshold, the terminal sends second indication information; correspondingly, the access network device receives the second indication information.

[0180] S403: The access network device reconfigures uplink resources for the terminal according to the second instruction information.

[0181] In some possible ways, the second indication information explicitly indicates to reconfigure uplink resources for the terminal, and the access network device can reconfigure uplink resources for the terminal, thereby avoiding or reducing data conflicts generated when the terminal performs cross-satellite switching.

[0182] In other possible implementations, the second indication information includes the difference between the first propagation delay and the second propagation delay. The access network device can reconfigure uplink resources for the terminal based on this difference. Optionally, the access network device can release conflicting uplink resources. For example, as shown in Figure 2B, if subframe 3 sent by the terminal to the source cell and subframe 4 sent by the terminal to the target cell conflict in time, the access network device can release resources for subframe 4. This approach can avoid data conflicts that occur when the terminal performs inter-satellite handover.

[0183] Optionally, the method shown in FIG4 further includes step H1.

[0184] Step H1: The first cell sends a first indication message to the terminal; accordingly, the terminal receives the first indication message from the first cell. The first indication message can be used to indicate that the terminal can synchronize uplink with the second satellite without triggering a random access process.

[0185] The specific content of step H1 can be found in S301 and will not be repeated here.

[0186] Using the method shown in Figure 4, when the difference between the first propagation delay and the second propagation delay is greater than a second threshold, the terminal can send a second indication message, which can be used to instruct the terminal to reconfigure uplink resources. The first propagation delay is related to the terminal and the first satellite serving the terminal before the handoff, while the second propagation delay is related to the terminal and the second satellite serving the terminal after the handoff. This allows the access network device to reconfigure uplink resources for the terminal in inter-satellite handoff scenarios, thereby avoiding or reducing data conflicts that may occur during inter-satellite handoffs, thus resolving Problem 2 mentioned above.

[0187] Based on the same technical concept as the above-mentioned method embodiment, the embodiment of the present application provides a corresponding communication device, which can be used to perform the functions of the relevant steps in the above-mentioned method embodiment. This function can be implemented by hardware, can be implemented by software, or can be implemented by hardware executing the corresponding software. The hardware or software includes one or more modules corresponding to the above-mentioned functions. The communication device can be a terminal, or can be a module in the terminal (such as a circuit or chip), or can be a logical node, logical module or software that can implement all or part of the terminal functions; or the communication device can be an access network device or a module in the access network device (such as a circuit or chip), or can be a logical node, logical module or software that can implement all or part of the access network device functions.

[0188] In one possible implementation, the structure of the communication device provided in the embodiment of the present application is shown in FIG5 , and includes a processing unit 502. Optionally, the communication device further includes an interface unit 501. The functions of each unit in the communication device 500 are described below.

[0189] The interface unit 501 is used to input and / or output information. Input information can be replaced by receiving information, and output information can be replaced by sending information. When outputting information, the interface unit 501 can output information to other devices outside the communication device 500, or it can output information to other units in the communication device 500. In some embodiments, the interface unit 501 can be implemented by at least one of a physical interface, a communication module, a communication interface, and an input / output interface. In other embodiments, the interface unit 501 can be implemented by an interface circuit, for example, a mobile communication module. The mobile communication module may include one or more of at least one antenna, at least one filter, a switch, a power amplifier, a low noise amplifier (LNA), etc.

[0190] The processing unit 502 can be used to support the communication device 500 in performing the processing actions in the above-mentioned method embodiment. The processing unit 502 can be implemented by one or more processors. For example, the processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor can be a microprocessor or any conventional processor.

[0191] In one embodiment, the communication device 500 is applied to the terminal in the embodiment of the present application shown in Figure 3. The specific functions of the processing unit 502 in this embodiment are introduced below.

[0192] The processing unit 502 is used to: receive first indication information from the first cell corresponding to the first satellite through the interface unit 501, where the first indication information is used to instruct the terminal to perform uplink synchronization with the second satellite without triggering a random access process; after the terminal is in the coverage of the second satellite, if the first SSB and the second SSB are the same, perform uplink synchronization with the second satellite without triggering a random access process, the first SSB is used for communication between the terminal and the first satellite, and the second SSB is used for communication between the terminal and the second satellite.

[0193] In some possible embodiments, the processing unit 502 is further configured to: after the terminal is in the coverage of the second satellite, if the first SSB and the second SSB are the same, perform uplink synchronization with the second satellite without triggering a random access process.

[0194] In other possible embodiments, the processing unit 502 is further used to: after the terminal is in the coverage of the second satellite, if the first SSB and the second SSB are the same and the signal quality of the second SSB is less than or equal to the first threshold, then uplink synchronization with the second satellite is performed through a random access process.

[0195] Optionally, the processing unit 502 is also used to: receive resource configuration information of the second cell corresponding to the first cell or the second satellite through the interface unit 501, where the resource configuration information is used to configure uplink resources; after the terminal is in the coverage of the second satellite, if the first SSB and the second SSB are the same, and the signal quality of the second SSB is less than or equal to the first threshold, then send a message to the second cell through the uplink resources through the interface unit 501.

[0196] In some implementations, the processing unit 502 is further configured to: after the terminal is in the coverage of the second satellite, if the first SSB and the second SSB are different, perform uplink synchronization with the second satellite through a random access process.

[0197] In other implementations, the processing unit 502 is also used to: receive resource configuration information from the first cell or the second cell corresponding to the second satellite through the interface unit 501, and the resource configuration information is used to configure uplink resources; after the terminal is in the coverage of the second satellite, if the first SSB and the second SSB are different, send a message to the second cell through the uplink resources through the interface unit 501.

[0198] Optionally, the processing unit 502 is further used to: send information indicating the second SSB to the second cell through uplink resources via the interface unit 501.

[0199] In another embodiment, the communication device 500 is applied to the terminal in the embodiment of the present application shown in Figure 4. The specific functions of the processing unit 502 in this embodiment are introduced below.

[0200] Processing unit 502 is configured to determine a difference between a first propagation delay and a second propagation delay, where the first propagation delay is the propagation delay of a service link between the terminal and a first cell corresponding to a first satellite, and the second propagation delay is the propagation delay of a service link between the terminal and a second cell corresponding to a second satellite, where the first satellite is a satellite providing service to the terminal before handover, and the second satellite is a satellite providing service to the terminal after handover. If the difference is greater than a second threshold, second indication information is sent via interface unit 501, where the second indication information is used to instruct reconfiguration of uplink resources for the terminal.

[0201] In some possible embodiments, the processing unit 502 is specifically configured to predict a difference between the first propagation delay and the second propagation delay at at least one of the following moments: a moment when the first satellite stops providing service to the terminal, a moment when the second satellite starts providing service to the terminal, and a moment when the terminal accesses the second satellite.

[0202] In another embodiment, the communication device 500 is applied to the access network device in the embodiment of the present application shown in Figure 4. The specific functions of the processing unit 502 in this embodiment are introduced below.

[0203] The processing unit 502 is configured to: receive, through the interface unit 501, second indication information sent by the terminal when a difference between a first propagation delay and a second propagation delay is greater than a second threshold, where the second indication information is used to instruct reconfiguration of uplink resources for the terminal, where the first propagation delay is a propagation delay of a service link between the terminal and a first cell corresponding to a first satellite, where the second propagation delay is a propagation delay of a service link between the terminal and a second cell corresponding to a second satellite, where the first satellite is a satellite providing service to the terminal before handover, and where the second satellite is a satellite providing service to the terminal after handover; and reconfigure uplink resources for the terminal based on the second indication information.

[0204] A more detailed description of the processing unit 502 and the interface unit 501 can be directly obtained by referring to the relevant descriptions in the method embodiments shown in Figures 3 and 4, and will not be repeated here.

[0205] It should be noted that the division of modules in the above embodiments of the present application is illustrative and is only a logical functional division. In actual implementation, there may be other division methods. In addition, the functional units in the various embodiments of the present application may be integrated into a processing unit, or may exist separately physically, or two or more units may be integrated into a single unit. The above-mentioned integrated units may be implemented in the form of hardware or in the form of software functional units.

[0206] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0207] In one possible implementation, the communication device provided in an embodiment of the present application is shown in FIG6 , where the communication device 600 includes a processor 602. Optionally, the communication device 600 further includes an interface circuit 601 and a memory 603. The interface circuit 601, the processor 602, and the memory 603 are coupled to each other.

[0208] Optionally, the interface circuit 601, the processor 602, and the memory 603 are coupled to each other via a bus 604. Bus 604 may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. Buses can be classified as address buses, data buses, control buses, etc. For ease of illustration, FIG6 shows only one thick line, but this does not mean that there is only one bus or only one type of bus.

[0209] Interface circuit 601 is used to input and / or output information. Inputting information can be replaced by receiving information, and outputting information can be replaced by sending information. When outputting information, interface circuit 601 can output information to other devices outside of communication device 600, or to other units within communication device 600. Exemplarily, interface circuit 601 can be implemented via at least one of a physical interface, a communication module, a communication interface, an input / output interface, and a mobile communication module. The mobile communication module may include one or more of at least one antenna, at least one filter, a switch, a power amplifier, an LNA, and the like.

[0210] Processor 602 can be used to support communication device 600 in executing the processing actions in the above-described method embodiments. When communication device 600 is used to implement the above-described method embodiments, processor 602 can also be used to implement the functions of processing unit 502. Processor 602 can be a CPU, other general-purpose processors, DSPs, ASICs, FPGAs, other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor.

[0211] In one embodiment, the communication device 600 is applied to the terminal in the embodiment of the present application shown in Figure 3. The specific functions of the processor 602 in this embodiment are introduced below.

[0212] The processor 602 is configured to: receive first indication information from a first cell corresponding to a first satellite through the interface circuit 601, where the first indication information is used to instruct the terminal to perform uplink synchronization with the second satellite without triggering a random access process; after the terminal is within the coverage of the second satellite, if the first SSB and the second SSB are the same, perform uplink synchronization with the second satellite without triggering a random access process, where the first SSB is used for communication between the terminal and the first satellite, and the second SSB is used for communication between the terminal and the second satellite.

[0213] In another embodiment, the communication device 600 is applied to the terminal in the embodiment of the present application shown in Figure 4. The specific functions of the processor 602 in this embodiment are introduced below.

[0214] Processor 602 is configured to determine a difference between a first propagation delay and a second propagation delay, where the first propagation delay is a propagation delay of a service link between a terminal and a first cell corresponding to a first satellite, and the second propagation delay is a propagation delay of a service link between the terminal and a second cell corresponding to a second satellite, where the first satellite is a satellite providing service to the terminal before handover, and the second satellite is a satellite providing service to the terminal after handover. If the difference is greater than a second threshold, send second indication information via interface circuit 601, where the second indication information is used to instruct reconfiguration of uplink resources for the terminal.

[0215] In another embodiment, the communication apparatus 600 is applied to the access network device in the embodiment of the present application shown in Figure 4. The specific functions of the processor 602 in this embodiment are introduced below.

[0216] The processor 602 is configured to: receive, through the interface circuit 601, second indication information sent by the terminal when a difference between a first propagation delay and a second propagation delay is greater than a second threshold, where the second indication information is used to instruct reconfiguration of uplink resources for the terminal, where the first propagation delay is a propagation delay of a service link between the terminal and a first cell corresponding to a first satellite, the second propagation delay is a propagation delay of a service link between the terminal and a second cell corresponding to a second satellite, the first satellite is a satellite providing service to the terminal before handover, and the second satellite is a satellite providing service to the terminal after handover; and reconfigure uplink resources for the terminal based on the second indication information.

[0217] The specific functions of the processor 602 can refer to the description of the communication method provided in the above embodiments and examples of the present application, as well as the specific functional description of the communication device 500 in the embodiment of the present application shown in Figure 5, and will not be repeated here.

[0218] The memory 603 is used to store program instructions and / or data, etc. Specifically, the program instructions may include program code, which includes computer operation instructions. The memory 603 may include RAM, and may also include non-volatile memory (non-volatile memory), such as at least one disk storage. The processor 602 executes the program instructions stored in the memory 603 and uses the data stored in the memory 603 to implement the above functions, thereby realizing the communication method provided in the above embodiment of the present application. The memory 603 can be integrated with the processor 602, or it can be a memory outside the communication device.

[0219] It will be appreciated that the memory 603 in FIG. 6 of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a ROM, a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a RAM, which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that memory of the systems and methods described herein is intended to comprise, but not be limited to, these and any other suitable types of memory.

[0220] Based on the above embodiments, an embodiment of the present application further provides a computer program product including computer-executable instructions. When the computer program product is run, the method provided in the above embodiments is executed.

[0221] Based on the above embodiments, an embodiment of the present application further provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a computer, the computer executes the method provided in the above embodiments.

[0222] The storage medium may be any available medium that can be accessed by a computer. By way of example and not limitation, computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer.

[0223] Based on the above embodiments, an embodiment of the present application further provides a chip, which is used to read a computer program stored in a memory to implement the method provided in the above embodiments.

[0224] Based on the above embodiments, embodiments of the present application provide a chip system, which includes a processor for supporting a computer device to implement the functions involved in each device in the above embodiments. In one possible design, the chip system also includes a memory for storing the necessary programs and data for the computer device. The chip system can be composed of a chip or can include a chip and other discrete devices.

[0225] In the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0226] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each flow and / or box in the flow chart and / or block diagram, as well as the combination of the flow chart and / or box in the flow chart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for implementing the functions specified in one or more flow charts and / or one or more boxes in the block diagram.

[0227] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a product including an instruction device that implements the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0228] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0229] In this application, "at least one" means one or more, and "more" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. In the text description of this application, the character " / " generally indicates that the previous and next associated objects are in an "or" relationship. In the formulas of this application, the character " / " can represent a division sign.

[0230] It is understood that the various numbers used in the embodiments of this application are merely for ease of description and are not intended to limit the scope of the embodiments of this application. The order of the sequence numbers of the above-mentioned processes does not necessarily imply a specific order of execution; the order of execution of the processes should be determined by their functions and inherent logic.

[0231] Obviously, those skilled in the art may make various changes and modifications to the present application without departing from the scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include these modifications and variations.

Claims

1. A communication method, characterized in that: Applied to terminals, including: receiving first indication information from a first cell corresponding to a first satellite, where the first indication information is used to instruct the terminal to perform uplink synchronization with a second satellite without triggering a random access process; After the terminal is in the coverage of the second satellite, if the first synchronization signal and physical broadcast channel PBCH block SSB and the second SSB are the same, uplink synchronization with the second satellite is performed without triggering a random access process, and the first SSB is used for communication between the terminal and the first satellite, and the second SSB is used for communication between the terminal and the second satellite.

2. The method according to claim 1, characterized in that The method performs uplink synchronization with the second satellite by not triggering a random access process, comprising: If the signal quality of the second SSB is greater than the first threshold, uplink synchronization with the second satellite is performed without triggering a random access process.

3. The method according to claim 2, characterized in that Also includes: After the terminal is in the coverage of the second satellite, if the first SSB is the same as the second SSB and the signal quality of the second SSB is less than or equal to the first threshold, uplink synchronization is performed with the second satellite through a random access process.

4. The method according to claim 1 or 2, characterized in that: Also includes: receiving resource configuration information of a second cell corresponding to the first cell or the second satellite, where the resource configuration information is used to configure uplink resources; After the terminal is in the coverage of the second satellite, if the first SSB is the same as the second SSB and the signal quality of the second SSB is less than or equal to a first threshold, a message is sent to the second cell through the uplink resources.

5. The method according to claim 1 or 2, characterized in that: Also includes: After the terminal is in the coverage of the second satellite, if the first SSB and the second SSB are different, uplink synchronization is performed with the second satellite through a random access process.

6. The method according to claim 1 or 2, characterized in that: Also includes: receiving resource configuration information of a second cell corresponding to the first cell or the second satellite, where the resource configuration information is used to configure uplink resources; After the terminal is in the coverage of the second satellite, if the first SSB and the second SSB are different, a message is sent to the second cell through the uplink resources.

7. The method according to claim 4 or 6, characterized in that Also includes: Information indicating the second SSB is sent to the second cell via the uplink resources.

8. The method according to any one of claims 1 to 7, characterized in that A second cell corresponding to the second satellite has a cell identifier that is the same as or different from that of the first cell.

9. A communication method, characterized in that: Applied to terminals, including: determining a difference between a first propagation delay and a second propagation delay, wherein the first propagation delay is a propagation delay of a service link between the terminal and a first cell corresponding to a first satellite, and the second propagation delay is a propagation delay of a service link between the terminal and a second cell corresponding to a second satellite, wherein the first satellite is a satellite providing service to the terminal before the terminal is switched, and the second satellite is a satellite providing service to the terminal after the terminal is switched; In a case where the difference is greater than a second threshold, second indication information is sent, where the second indication information is used to instruct reconfiguration of uplink resources for the terminal.

10. The method according to claim 9, characterized in that The second indication information includes the difference.

11. The method according to claim 9 or 10, characterized in that Determining a difference between a first propagation delay and a second propagation delay includes: Predicting a difference between the first propagation delay and the second propagation delay at at least one of the following times: The time when the first satellite stops providing services for the terminal, the time when the second satellite starts providing services for the terminal, and the time when the terminal accesses the second satellite.

12. A communication method, characterized in that: Applied to access network equipment, including: receiving second indication information sent by the terminal when the difference between the first propagation delay and the second propagation delay is greater than a second threshold, The second indication information is used to instruct to reconfigure uplink resources for the terminal, the first propagation delay is a propagation delay of a service link between the terminal and a first cell corresponding to a first satellite, the second propagation delay is a propagation delay of a service link between the terminal and a second cell corresponding to a second satellite, the first satellite is a satellite that provides services for the terminal before the terminal is switched, and the second satellite is a satellite that provides services for the terminal after the terminal is switched; Reconfigure uplink resources for the terminal according to the second indication information.

13. The method according to claim 12, characterized in that The second indication information includes the difference.

14. The method according to claim 12 or 13, characterized in that The difference is the difference between the first propagation delay and the second propagation delay at at least one of the following moments: The time when the first satellite stops providing services for the terminal, the time when the second satellite starts providing services for the terminal, and the time when the terminal accesses the second satellite.

15. A communication device, characterized in that: include: An interface unit for receiving and sending information; A processing unit, configured to execute the method according to any one of claims 1 to 14 through the interface unit.

16. A communication device, characterized in that: The method comprises a processor configured to execute the method according to any one of claims 1 to 14.

17. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program or instruction. When the computer program or instruction is executed by the communication device, the method according to any one of claims 1 to 14 is implemented.

18. A computer program product, characterized in that The computer program product comprises: a computer program code, and when the computer program code is executed, the method according to any one of claims 1 to 14 is implemented.

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