NTN-based cell handover method, and device

Abstract

The embodiments of the present application relate to the technical field of communications. Provided are an NTN-based cell handover method, and a device. The method comprises: when a terminal device is handed over from a source NTN access network device to a target NTN access network device, the target NTN access network device reserving uplink resources for the terminal device at a specified location, and indicating the reserved uplink resources by means of a conditional handover start time, a first time domain length, and resource indication information. The terminal device finds uplink resources at a specified location by means of the conditional handover start time, the first time domain length, and the resource indication information, and uses the uplink resources at the specified location to send a message indicating completion of a cell handover, thereby significantly reducing resource waste caused by uplink resource reservation, and also avoiding a handover failure caused by the absence of uplink scheduling for the terminal device.

Description

A method and device for cell handover based on NTN network

[0001] This application claims priority to Chinese patent application filed on November 28, 2024, with application number 202411753372.1 and entitled "A method and apparatus for cell handover based on NTN network", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of communication technology, and in particular to a method and device for cell handover based on an NTN network. Background Technology

[0003] A crucial component of communication systems is non-terrestrial network (NTN) communication. In satellite communication scenarios, the rapid movement of satellites necessitates frequent switching between different satellite cells by terminal devices to ensure service continuity.

[0004] During the aforementioned handover process, based on the current cell handover procedure, uplink resources need to be reserved for terminal devices. However, due to the high transmission latency of NTN communication, the handover time is difficult to predict. Currently, there is a problem of wasting uplink resources when reserving them. Summary of the Invention

[0005] This application provides a method and apparatus for cell handover based on an NTN network, which can reduce the waste of Physical Uplink Shared Channel (PUSCH) resources and avoid handover failure caused by the lack of uplink scheduling by the terminal device. To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0006] In a first aspect, embodiments of this application provide a method for cell handover based on an NTN network, wherein the NTN network includes a source NTN access network device and a target NTN access network device. This method can be performed by network devices deployed on a satellite, such as the source NTN access network device, or by components (e.g., chips or circuits) configured within the NTN access network device. This application does not limit the scope of this method.

[0007] The above method includes: when the source NTN access network device determines that the terminal device will be switched from the source NTN access network device to the target NTN access network device, the source NTN access network device sends a cell handover request to the target NTN access network device; and receives a handover request response message sent by the target NTN access network device, the handover request response message including at least: time-based conditional handover parameters, and resource indication information for indicating uplink resources in the time domain, wherein the time-based conditional handover parameters include a first time domain length and a conditional handover start time, and the uplink resources are located within the first time domain length starting from the conditional handover start time.

[0008] Based on the above technical solution, after receiving a cell handover request, the target NTN access network device reserves uplink resources for the terminal device within a first time domain length starting from the conditional handover start time, and indicates the location of the reserved uplink resources through time-based conditional handover parameters and resource indication information. After receiving the handover request response message, the source NTN access network device can send the time-based conditional handover parameters and resource indication information to the terminal device. Thus, the terminal device can subsequently initiate a handover at the conditional handover start time, select the uplink resources reserved on the PUSCH for this handover within the first time domain length, and send a message indicating completion of the cell handover to the target NTN access network device. Because the conditional handover start time, the first time domain length, and the resource indication information are clearly defined, the target NTN access network device reserves PUSCH uplink resources at a specified location, and the terminal device uses the uplink resources at that specified location to send the message indicating completion of the cell handover. This greatly reduces resource waste caused by uplink resource reservation and avoids handover failure due to the terminal device's lack of uplink scheduling.

[0009] In conjunction with the first aspect described above, in some implementations of the first aspect, the resource indication information is a resource indication bitmap. The resource indication bitmap includes multiple bits, each of which corresponds to a resource allocation unit, and each bit indicates whether uplink resources are reserved within the corresponding resource allocation unit. Therefore, the terminal device can determine the resource allocation unit with reserved uplink resources based on the resource indication bitmap.

[0010] In conjunction with the first aspect and the aforementioned implementation, in some implementations of the first aspect, the method further includes: sending a first message to the terminal device, the first message instructing the terminal device to switch to the target NTN access network device, the first message including at least: time-based conditional handover parameters, and resource indication information for indicating uplink resources in the time domain. Accordingly, the terminal device can receive the first message, and then, through the time-based conditional handover parameters and resource indication information, find the required resources on the PUSCH, and then use those resources to send a message indicating completion of cell handover.

[0011] It should be understood that the first message may also include parameter information of the target NTN access network device, which is used by the terminal device to access the target NTN access network device.

[0012] Combining the first aspect and the above implementation methods, in some implementations of the first aspect, the first message is a Radio Resource Control (RRC) reconfiguration message. The source NTN access network device can instruct the terminal device to perform cell handover through the RRC reconfiguration message, and can carry time-based conditional handover parameters and resource indication information through the RRC message. This eliminates the need for additional messages to carry relevant information, saving signaling overhead and improving cell handover efficiency.

[0013] In conjunction with the first aspect and the above implementation, in some implementations of the first aspect, before sending a cell handover request to the target NTN access network device, the method further includes: detecting that the signal quality of the terminal device is less than a preset threshold; and determining to hand over the terminal device from the source NTN access network device to the target NTN access network device. Thus, when the signal of the terminal device is poor, the source NTN access network device can promptly instruct the terminal device to hand over the cell, thereby ensuring the network communication quality of the terminal device.

[0014] In conjunction with the first aspect and the aforementioned implementation methods, in some implementations of the first aspect, before sending a cell handover request to the target NTN access network device, the method further includes: predicting, based on the relative movement trajectory and relative movement speed of the terminal device relative to the source NTN access network device, that the terminal device will leave the coverage area of ​​the source NTN access network device within a preset time period; and determining to hand over the terminal device from the source NTN access network device to the target NTN access network device. Thus, when the terminal device is about to leave the coverage area of ​​the source NTN access network device, the cell of the terminal device can be switched in a timely manner to ensure the network communication quality of the terminal device.

[0015] Secondly, embodiments of this application provide a method for cell handover based on an NTN network, wherein the NTN network includes a source NTN access network device and a target NTN access network device. This method can be performed by network devices deployed on a satellite, such as the target NTN access network device, or by components (e.g., chips or circuits) configured in the target NTN access network device. This application does not limit the scope of this method.

[0016] The above method includes: the target NTN access network device receiving a cell handover request sent by the source NTN access network device; configuring time-based conditional handover parameters for the terminal device, and resource indication information for indicating uplink resources in the time domain; sending a handover request response message to the source NTN access network device, the handover request response message including at least: time-based conditional handover parameters, and resource indication information for indicating uplink resources in the time domain, the time-based conditional handover parameters including a first time domain length and a conditional handover start time, the uplink resources being located within the first time domain length starting from the conditional handover start time.

[0017] Based on the above technical solution, after receiving a cell handover request, the target NTN access network device reserves uplink resources for the terminal device within a first time domain length starting from the conditional handover start time, and indicates the location of the reserved uplink resources through time-based conditional handover parameters and resource indication information. The target NTN access network device sends a handover request response message to the source NTN access network device, which includes time-based conditional handover parameters and resource indication information, so that the source NTN access network device can send these parameters and information to the terminal device. Therefore, the terminal device can subsequently initiate handover at the conditional handover start time, select the PUSCH as the reserved uplink resource for this handover within the first time domain length, and send a message to the target NTN access network device indicating completion of the cell handover. By specifying the start time of conditional handover, the length of the first time domain, and resource indication information, the target NTN access network device reserves PUSCH uplink resources at a designated location. The terminal device uses the uplink resources at the designated location to send a message indicating the completion of cell handover. This can greatly reduce the resource waste caused by uplink resource reservation and also avoid the problem of handover failure due to the terminal device not having uplink scheduling.

[0018] In conjunction with the second aspect described above, in some implementations of the second aspect, the resource indication information is a resource indication bitmap. The resource indication bitmap includes multiple bits, each of which corresponds to a resource allocation unit, and each bit indicates whether uplink resources are reserved within the corresponding resource allocation unit. Thus, the terminal device can, based on the indication of the resource indication bitmap, send a message indicating completion of cell handover on the uplink resources reserved by the target NTN access network device.

[0019] In conjunction with the second aspect and the above implementation, in some implementations of the second aspect, the method further includes: reserving uplink resources for the terminal device within a first time domain length according to the resource indication bitmap. This allows the terminal device to use the reserved uplink resources to send a message indicating completion of cell handover.

[0020] In conjunction with the second aspect and the aforementioned implementation, in some implementations of the second aspect, the resource indication bitmap is a bitmap indicating the resources of the target NTN access network device starting from the first scheduling unit after the conditional handover start time. This allows the uplink resources indicated by the resource indication bitmap to be aligned with the scheduling unit of the target NTN access network device.

[0021] In conjunction with the second aspect and the above implementation methods, in some implementations of the second aspect, the method further includes: determining the granularity of resource allocation, with different granularities corresponding to different numbers of resource allocation units; and dividing uplink resources into multiple resource allocation units based on the granularity of resource allocation. In this way, the target NTN access network device can control the granularity of reserved uplink resources, thus more effectively reducing resource waste caused by uplink resource reservation.

[0022] In conjunction with the second aspect and the above implementation, in some implementations of the second aspect, the method further includes: receiving a second message, wherein the second message is sent by the terminal device through uplink resources within a first time domain length, and the second message instructs the terminal device to complete cell handover.

[0023] In conjunction with the second aspect and the aforementioned implementation methods, in some implementations of the second aspect, the second message is an RRC reconfiguration completion message. Thus, the RRC reconfiguration completion message can be used to indicate that the terminal device has completed cell handover, facilitating the target NTN access network device to determine that the terminal device has completed cell handover based on this message.

[0024] Thirdly, embodiments of this application provide a method for cell handover based on an NTN network, wherein the NTN network includes a source NTN access network device and a target NTN access network device. This method can be executed by a terminal device, or by a component (e.g., a chip or circuit) configured in the terminal device. This application does not limit the scope of this method.

[0025] The method includes: a terminal device receiving a first message sent by a source NTN access network device, the first message instructing the terminal device to switch to a target NTN access network device, the first message including at least: time-based conditional handover parameters, and resource indication information for indicating uplink resources in the time domain, the time-based conditional handover parameters including a first time domain length and a conditional handover start time, the uplink resources being located within the first time domain length starting from the conditional handover start time; within the first time domain length, sending a second message to the target NTN access network device using the nearest uplink resource after the current time, the second message instructing the terminal device to complete cell handover.

[0026] Based on the above technical solution, the terminal device can initiate handover at the conditional handover start time and select the PUSCH as the uplink resource reserved for this handover within the first time domain length. It then sends a message instructing the target NTN access network device to complete the cell handover. Since the conditional handover start time, the first time domain length, and the resource indication information are clearly defined, and the target NTN access network device reserves PUSCH uplink resources at a designated location, the terminal device can use these uplink resources to send the message instructing the completion of the cell handover. This significantly reduces resource waste caused by uplink resource reservation and avoids handover failure due to the terminal device's lack of uplink scheduling.

[0027] In conjunction with the third aspect described above, in some implementations of the third aspect, the resource indication information is a resource indication bitmap. The resource indication bitmap includes multiple bits, each of which corresponds to a resource allocation unit, and each bit indicates whether uplink resources are reserved within the corresponding resource allocation unit. Therefore, the terminal device can determine the location of the reserved uplink resources based on the resource indication bitmap.

[0028] Combining the third aspect and the aforementioned implementation methods, in some implementations of the third aspect, the first message is an RRC reconfiguration message. Thus, the source NTN access network device can instruct the terminal device to perform cell handover via the RRC reconfiguration message, and can carry time-based conditional handover parameters and resource indication information through the RRC message. This eliminates the need for additional messages to carry relevant information, saving signaling overhead and improving cell handover efficiency.

[0029] In conjunction with the third aspect and the aforementioned implementation methods, in some implementations of the third aspect, the second message is an RRC reconfiguration completion message. Thus, the RRC reconfiguration completion message can be used to indicate that the terminal device has completed cell handover, facilitating the target NTN access network device to determine that the terminal device has completed cell handover based on this message.

[0030] Fourthly, embodiments of this application provide a communication device, including various modules or units for performing the methods of the first aspect and any implementation thereof.

[0031] Fifthly, embodiments of this application provide a communication device including various modules or units for performing the methods of the second aspect and any implementation thereof.

[0032] In a sixth aspect, embodiments of this application provide a communication apparatus, including various modules or units for performing the methods of the third aspect and any implementation thereof.

[0033] In a seventh aspect, embodiments of this application provide a communication device including a processor. The processor is coupled to a memory and can be used to execute instructions in the memory to implement the methods in the first aspect and any implementation thereof. Optionally, the device further includes a memory. Optionally, the device further includes a communication interface, and the processor is coupled to the communication interface.

[0034] In one implementation, the communication device is a network device, such as a source NTN access network device. In this case, the communication interface can be a transceiver or an input / output interface.

[0035] In another implementation, the communication device is a chip configured in a network device, such as a source NTN access network device. In this case, the communication interface can be an input / output interface.

[0036] Optionally, the transceiver can be a transceiver circuit. Optionally, the input / output interface can be an input / output circuit.

[0037] Eighthly, a communication device is provided, including a processor. The processor is coupled to a memory and can be used to execute instructions in the memory to implement the methods of the second aspect and any implementation thereof.

[0038] Optionally, the device further includes a memory. Optionally, the device further includes a communication interface, to which the processor is coupled.

[0039] In one implementation, the communication device is a network device, such as a target NTN access network device. In this case, the communication interface can be a transceiver or an input / output interface.

[0040] In another implementation, the communication device is a chip configured in a network device, such as a target NTN access network device. In this case, the communication interface can be an input / output interface.

[0041] Optionally, the transceiver can be a transceiver circuit. Optionally, the input / output interface can be an input / output circuit.

[0042] A ninth aspect provides a communication device including a processor. The processor is coupled to a memory and can be used to execute instructions in the memory to implement the methods of the third aspect and any implementation thereof.

[0043] Optionally, the device further includes a memory. Optionally, the device further includes a communication interface, to which the processor is coupled.

[0044] In one implementation, the communication device is a terminal device. In this case, the communication interface can be a transceiver or an input / output interface.

[0045] In another implementation, the communication device is a chip configured in the terminal device. In this case, the communication interface can be an input / output interface.

[0046] Optionally, the transceiver can be a transceiver circuit. Optionally, the input / output interface can be an input / output circuit.

[0047] A tenth aspect provides a processor, including: an input circuit, an output circuit, and a processing circuit. The processing circuit is used to receive signals through the input circuit and transmit signals through the output circuit, causing the processor to execute the methods of the first aspect, the second aspect, or the third aspect, and any implementation thereof.

[0048] In specific implementation, the processor can be one or more chips, the input circuit can be input pins, the output circuit can be output pins, and the processing circuit can be transistors, gate circuits, flip-flops, and various logic circuits. The input signal received by the input circuit can be received and input by, for example, but not limited to, a receiver, and the signal output by the output circuit can be, for example, but not limited to, output to and transmitted by a transmitter. Furthermore, the input circuit and the output circuit can be the same circuit, which is used as both the input circuit and the output circuit at different times. This application does not limit the specific implementation of the processor and various circuits.

[0049] Eleventhly, a processing apparatus is provided, including a processor and a memory. The processor is configured to read instructions stored in the memory and to receive signals via a receiver and transmit signals via a transmitter to execute the methods of the first, second, or third aspects, and any implementation thereof.

[0050] Optionally, there may be one or more processors and one or more memories.

[0051] Alternatively, the memory can be integrated with the processor, or the memory can be set up separately from the processor.

[0052] In specific implementation, the memory can be a non-transitory memory, such as read-only memory (ROM), which can be integrated with the processor on the same chip or set on different chips. The embodiments of this application do not limit the type of memory or the way the memory and processor are set.

[0053] It should be understood that the relevant data interaction process, such as sending indication information, can be the process of the processor outputting indication information, and receiving capability information can be the process of the processor receiving input capability information. Specifically, the data output by the processor can be sent to the transmitter, and the input data received by the processor can come from the receiver. Here, the transmitter and receiver can be collectively referred to as a transceiver.

[0054] The processing device mentioned in the eleventh aspect above can be one or more chips. The processor in the processing device can be implemented in hardware or software. When implemented in hardware, the processor can be a logic circuit, integrated circuit, etc.; when implemented in software, the processor can be a general-purpose processor that reads software code stored in memory. The memory can be integrated into the processor or located outside the processor and exist independently.

[0055] In a twelfth aspect, embodiments of this application provide a network device including a processor, a memory, and a transceiver. The transceiver is used to send and receive data, the memory is used to store code instructions, and the processor is used to execute the code instructions. When the processor executes the code instructions stored in the memory, it instructs the network device to perform the methods described in the first or second aspect and any implementation thereof.

[0056] In a thirteenth aspect, embodiments of this application provide a terminal device, including a processor, a memory, and a transceiver. The transceiver is used to send and receive data, the memory is used to store code instructions, and the processor is used to execute the code instructions. When the processor executes the code instructions stored in the memory, it instructs the terminal device to execute the method described in the third aspect and any implementation thereof.

[0057] In a fourteenth aspect, embodiments of this application provide a computer-readable storage medium storing a computer program or instructions that, when executed on a computer, cause the computer to perform the methods described in any of the first, second, or third aspects and any of the implementations of the first, second, or third aspects.

[0058] In a fifteenth aspect, embodiments of this application provide a chip or chip system, which includes at least one processor and a communication interface. The communication interface and the at least one processor are interconnected via a circuit. The at least one processor is used to run computer programs or instructions to perform the methods of the first aspect, the second aspect, or the third aspect, and any implementation thereof. The communication interface in the chip can be an input / output interface, a pin, or a circuit, etc.

[0059] In a sixteenth aspect, embodiments of this application provide a computer program product including a computer program, which, when run on a computer, causes the computer to perform the first aspect, the second aspect, or the third aspect, and the method in any one of the implementations of the first aspect, the second aspect, or the third aspect.

[0060] It should be understood that the fourth and seventh aspects of this application correspond to the technical solutions of the first aspect of this application, the fifth and eighth aspects of this application correspond to the technical solutions of the second aspect of this application, the sixth, ninth, and thirteenth aspects of this application correspond to the technical solutions of the third aspect of this application, the twelfth aspect of this application corresponds to the technical solutions of the first or second aspect of this application, and the tenth, eleventh, fourteenth to sixteenth aspects of this application correspond to the technical solutions of the first, second, or third aspect of this application. The beneficial effects obtained by each aspect and the corresponding feasible implementation are similar, and will not be described again. Attached Figure Description

[0061] Figure 1 is a schematic diagram of a satellite communication scenario provided in an embodiment of this application;

[0062] Figure 2 is a schematic diagram of the network architecture of the satellite communication system provided in an embodiment of this application;

[0063] Figure 3 is a flowchart illustrating a cell handover method provided in an embodiment of this application;

[0064] Figure 4 is a flowchart illustrating another cell handover method provided in an embodiment of this application;

[0065] Figure 5 is a flowchart illustrating another cell handover method provided in an embodiment of this application;

[0066] Figure 6 is a flowchart illustrating another cell handover method provided in an embodiment of this application;

[0067] Figure 7A is a schematic diagram of a parameter representation method provided in an embodiment of this application;

[0068] Figure 7B is a schematic diagram of a resource indicator bitmap indicating the location of resources according to an embodiment of this application;

[0069] Figure 7C is a schematic diagram of another resource indicator bitmap indicating resource location provided in an embodiment of this application;

[0070] Figure 7D is a schematic diagram of a resource indication bitmap aligned with a base station scheduling unit according to an embodiment of this application;

[0071] Figure 8 is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0072] Figure 9 is a schematic diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0073] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. In the description of this application, unless otherwise stated, " / " indicates that the objects before and after are in an "or" relationship. For example, A / B can represent A or B. "And / or" in this application is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone, where A and B can be singular or plural. Furthermore, in the description of this application, unless otherwise stated, "multiple" refers to two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple. Furthermore, to facilitate a clear description of the technical solutions in the embodiments of this application, the terms "first" and "second" are used in the embodiments of this application to distinguish identical or similar items with substantially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that "first" and "second" are not necessarily different. Meanwhile, in the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is being used as an example, illustration, or description. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of terms such as "exemplary" or "for example" is intended to present related concepts in a concrete manner for ease of understanding.

[0074] Furthermore, the network architecture and business scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0075] With the continuous development of communication technology, an important component of the current communication field is non-terrestrial network (NTN) communication technology, also known as satellite communication. In satellite communication scenarios, due to the rapid movement of satellites, terminal devices need to frequently switch between different satellite cells. For example, a terminal device needs to perform a cell handover every ten minutes to ensure service continuity.

[0076] For example, Figure 1 illustrates a schematic diagram of a satellite communication scenario provided in an embodiment of this application. As shown in Figure 1, this scenario includes satellite 101 and satellite 102. As shown in Figure 1(a), at the first moment, the cell coverage of satellite 101 covers the location of terminal device 103, while the cell coverage of satellite 102 does not cover the location of terminal device 103. As the satellites move, the coverage area of ​​satellite 101 gradually moves away from the location of terminal device 103, while the coverage area of ​​satellite 102 gradually moves closer to the location of terminal device 103. Therefore, at the second moment, as shown in Figure 1(b), terminal device 103 is located at the edge of the coverage area of ​​satellite 101 and within the coverage area of ​​satellite 102. At this time, in order to maintain service continuity, the terminal device needs to switch from the cell of satellite 101 to the cell of satellite 102, so that the terminal device can subsequently communicate through satellite 102.

[0077] In this application embodiment, the terminal device 103 is a terminal with wireless transceiver capabilities or a chip or chip system that can be installed on the terminal. This terminal can also be referred to as a terminal device, user equipment (UE), mobile station (MS), mobile terminal (MT), etc. The terminal can be a mobile phone, tablet computer, laptop computer, PDA, mobile internet device (MID), wearable device, virtual reality (VR) device, augmented reality (AR) device, wireless terminal in industrial control, wireless terminal in self-driving, wireless terminal in remote medical surgery, wireless terminal in smart grid, wireless terminal in transportation safety, wireless terminal in smart city, or wireless terminal in smart home, etc. This application embodiment does not limit the specific technology or device form used in the terminal.

[0078] Satellites 101 and 102 can be satellites with deployed access network equipment. For example, satellite 101 may have active NTN access network equipment deployed, and satellite 102 may have targeted NTN access network equipment deployed. Examples of access network equipment include: gNB (gembrane network unit), transmission reception point (TRP), evolved Node B (eNB), radio network controller (RNC), Node B (NB), base station controller (BSC), base transceiver station (BTS), home base station (e.g., home-evolved Node B, or home Node B, HNB), base band unit (BBU), etc.

[0079] It should be understood that in satellite communication scenarios, a single satellite can cover a cell area of ​​hundreds of thousands of square kilometers, but to cover the entire area, hundreds or thousands of satellites are still needed to form a network for coverage.

[0080] This application falls under the category of satellite communications. The technical solutions provided in the embodiments of this application can be applied to various communication systems, such as: Long Term Evolution (LTE) systems, LTE Frequency Division Duplex (FDD) systems, LTE Time Division Duplex (TDD) systems, Universal Mobile Telecommunication System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX) systems, 5th Generation (5G) mobile communication systems, and New Radio (NR), etc. The 5G mobile communication systems in the embodiments of this application include non-standalone (NSA) 5G mobile communication systems or standalone (SA) 5G mobile communication systems.

[0081] It should be understood that the technical solutions provided in this application can also be applied to future network application architectures, such as network application architectures based on the sixth-generation mobile communication system.

[0082] For example, Figure 2 is a schematic diagram of the network architecture of a satellite communication system provided in an embodiment of this application. As shown in Figure 2, ground terminal equipment accesses 5G access network equipment (such as 5G base stations) through a 5G New Radio interface. The 5G access network equipment is deployed on the satellite and connected to the ground core network through a wireless link. Simultaneously, wireless links exist between satellites to complete signaling interaction and user data transmission between base stations. The various network elements in Figure 2 and their interfaces are described below:

[0083] Terminal devices: Devices that support 5G New Radio, such as mobile devices like smartphones and tablets. Terminal devices can access satellite networks and initiate services such as calls and internet access through New Radio.

[0084] 5G base stations primarily provide wireless access services, allocate wireless resources to accessing terminal devices, and provide reliable wireless transmission protocols and data encryption protocols.

[0085] 5G Core Network: Handles user access control, mobility management, session management, user security authentication, billing, and other services. It consists of multiple functional units, which can be divided into control plane and data plane functional entities. The Access and Mobility Management Function (AMF) is responsible for user access management, security authentication, and mobility management. The User Plane Function (UPF) is responsible for managing user plane data transmission, traffic statistics, and other functions. The Session Management Function (SMF) is primarily responsible for interaction with the separate data plane.

[0086] Ground station: Responsible for forwarding signaling and service data between satellite base stations and the 5G core network.

[0087] 5G New Radio: The wireless link between a terminal and a base station.

[0088] Xn interface: The interface between 5G base stations, mainly used for signaling interactions such as handover.

[0089] NG interface: The interface between the 5G base station and the 5G core network.

[0090] In the aforementioned satellite communication system, when a terminal device switches from a source cell to a target cell, the terminal device needs to perform a random access to the target cell process. Specifically, Figure 3 shows a flowchart of a cell handover method provided in an embodiment of this application. Referring to Figure 3, the cell handover method may include the following steps S301-S305.

[0091] S301, the source base station sends a cell handover request to the target base station.

[0092] S302, the target base station sends a handover request response message to the source base station according to the cell handover request.

[0093] The handover request response message may include cell access-related information such as the preamble based on the non-contention-based Random Access Channel (RACH).

[0094] S303, the source base station sends a Radio Resource Control (RRC) reconfiguration message to the terminal device.

[0095] The RRC reconfiguration message may include cell access-related information such as the aforementioned non-contention-based RACH Preamble. The RRC reconfiguration message can instruct the terminal device to switch cells to the target base station.

[0096] S304, the terminal device initiates a non-contention-based random access to the target base station based on the RRC reconfiguration message in order to access the target base station.

[0097] S305: After switching cells, the terminal device sends an RRC reconfiguration complete message to the target base station.

[0098] The RRC reconfiguration complete message indicates that the cell handover is complete.

[0099] It should be noted that the detailed steps for the above-mentioned cell handover can be found in the descriptions in relevant technologies, and will not be repeated here.

[0100] In the above method, after the source base station decides to initiate a handover, it negotiates a handover with the target base station via the Xn interface. After the negotiation is completed, the source base station informs the terminal device of information such as a non-contention-based RACH preamble via an RRC reconfiguration message. Upon receiving the RRC reconfiguration message, the terminal device initiates a non-contention-based random access procedure to the target base station. After successfully accessing the target cell, the terminal device enters the connected state and sends an RRC reconfiguration completion message to the target base station, completing the cell handover process. When a terminal device performs a cell handover using a non-contention-based random access method, resources such as preamble sequences are required. However, due to the large coverage area of ​​satellite base stations and the large number of terminal devices they serve, there are insufficient resources to support multiple terminal devices performing cell handovers simultaneously in the aforementioned satellite communication scenario. Furthermore, if multiple terminal devices perform cell handovers simultaneously, it may lead to excessive RACH signaling overhead.

[0101] Based on the above issues, a cell handover scheme based on random access channel-less (RACH-less) has been proposed in satellite communication scenarios. However, in the RACH-less handover scheme, how the terminal device sends an RRC reconfiguration completion message to the target base station to complete the handover process is a problem that needs to be solved.

[0102] Figure 4 shows a flowchart illustrating a RACH-less cell handover method provided in an embodiment of this application. Referring to Figure 4, the cell handover method may include the following steps S401-S406.

[0103] S401, the source base station sends a cell handover request to the target base station.

[0104] In S402, the target base station and the source base station negotiate uplink grant to allocate uplink resources to the terminal equipment. Uplink grant can also be described as uplink authorization or uplink resource scheduling. Uplink resources are resources in the Physical Uplink Shared Link (PUSCH).

[0105] S403, the target base station sends a handover request response message to the source base station.

[0106] The uplink schedule allocated to the terminal device can be carried in the handover request response message.

[0107] S404, the source base station sends an RRC reconfiguration message to the terminal device.

[0108] The RRC reconfiguration message can carry the uplink schedule allocated to the terminal device as described above.

[0109] S405, the terminal device performs cell handover based on the RRC reconfiguration message and accesses the target base station.

[0110] S406 After the cell handover is completed, the terminal device sends an RRC reconfiguration complete message to the target base station according to the uplink scheduling.

[0111] It should be noted that the detailed steps for the above-mentioned cell handover can be found in the descriptions in relevant technologies, and will not be repeated here.

[0112] When switching cells using the method shown in Figure 4, in order for the terminal devices to send RRC reconfiguration complete messages, the target base station negotiates uplink scheduling with the source base station after receiving the cell handover request. This allows the target base station to allocate independent uplink resources to all terminal devices awaiting handover in advance. Since the target base station cannot accurately predict the cell handover completion time of the terminal devices under the source base station, the pre-allocated PUSCH uplink resources may be wasted.

[0113] Figure 5 shows a flowchart of another RACH-less cell handover method provided in an embodiment of this application. Referring to Figure 5, the cell handover method may include the following steps S501-S506.

[0114] S501, the source base station sends a cell handover request to the target base station.

[0115] S502, the target base station sends a handover request response message to the source base station.

[0116] S503, the source base station sends an RRC reconfiguration message to the terminal device.

[0117] S504, the target base station sends uplink scheduling to the terminal device on the Physical Downlink Control Channel (PDCCH).

[0118] S505: The terminal device performs cell handover based on the RRC reconfiguration message and accesses the target base station.

[0119] S506: After the cell handover is completed, the terminal device sends an RRC reconfiguration completion message to the target base station according to the received uplink scheduling.

[0120] It should be noted that the detailed steps for the above-mentioned cell handover can be found in the descriptions in relevant technologies, and will not be repeated here.

[0121] When handing over a cell using the method shown in Figure 5, in order for the terminal device to send an RRC reconfiguration complete message, the target base station sends uplink scheduling to the terminal device in advance via PDCCH. Since the target base station cannot accurately estimate the cell handover completion time of the terminal device under the source base station, the pre-allocated uplink scheduling resources may be wasted, affecting the resource utilization of the target base station. Furthermore, it may result in the terminal device having no available uplink resources when sending the RRC reconfiguration complete message, leading to handover failure.

[0122] In view of this, embodiments of this application provide a method for cell handover based on an NTN network, which can reduce resource waste caused by reserving uplink resources.

[0123] For example, consider a satellite communication scenario that includes a source NTN access network device (such as a first base station deployed on a first satellite), a target NTN access network device (such as a second base station deployed on a second satellite), and a terminal device. The terminal device is connected to the source NTN access network device and is located at the edge of the signal coverage area of ​​the source NTN access network device. The terminal device is also located within the signal coverage area of ​​the target NTN access network device, and it is necessary to switch the terminal device from the source NTN access network device to the target NTN access network device.

[0124] The connection of the terminal device to the source NTN access network device can also be described as the terminal device accessing the first cell included in the source NTN access network device. The signal coverage area of ​​the source NTN access network device can also be described as the signal coverage area of ​​the first cell. The connection of the terminal device to the target NTN access network device can also be described as the terminal device accessing the second cell included in the target NTN access network device. The signal coverage area of ​​the target NTN access network device can also be described as the signal coverage area of ​​the second cell. The handover from the source NTN access network device to the target NTN access network device can also be described as the handover from the first cell to the second cell.

[0125] Figure 6 is a flowchart illustrating a cell handover method based on an NTN network according to an embodiment of this application. As shown in Figure 6, the method may include the following steps S601-S606.

[0126] S601, if it is determined that the terminal device will be switched from the source NTN access network device to the target NTN access network device, the source NTN access network device sends a cell handover request to the target NTN access network device. Correspondingly, the target NTN access network device receives the cell handover request.

[0127] Access network equipment can measure and report configurations of terminal devices. Therefore, when the communication signal quality of a terminal device deteriorates to a preset threshold, the access network equipment can initiate a cell handover for that terminal device. Alternatively, the access network equipment can also predict the status of each terminal device based on information such as ephemeris data. If it predicts that a terminal device will leave the coverage area of ​​the current cell after a preset time, the access network equipment can initiate a cell handover for that terminal device.

[0128] For example, in this embodiment, the terminal device is connected to a source NTN access network device and is located at the edge of the source NTN access network device's coverage area. Therefore, the communication signal quality between the terminal device and the source NTN access network device is poor. In this case, the source NTN access network device determines to switch the terminal device to the target NTN access network device. This can be because the source NTN access network device receives a signal measurement report from the terminal device and detects that the signal quality is below a preset threshold (this can be either less than or equal to the preset threshold, and can be configured according to the actual situation in the specific implementation, without limitation here), thus determining that the terminal device needs to be switched from the source NTN access network device to the target NTN access network device. Alternatively, the source NTN access network device predicts the relative movement of the terminal device based on its relative movement trajectory and relative movement speed within its coverage area, thereby predicting that the terminal device will leave the coverage area of ​​the source NTN access network device within a preset time period, thus determining that the terminal device needs to be switched from the source NTN access network device to the target NTN access network device.

[0129] Specifically, in satellite communication scenarios, access network devices determine which cell, or NTN access network device, to switch the terminal device to, based on neighboring cell or ephemeris information. For example, in this embodiment, the source NTN access network device can determine to switch the terminal device to the target NTN access network device based on the neighboring cells of the first cell corresponding to the source NTN access network device as the second cell corresponding to the target NTN access network device. Alternatively, the source NTN access network device can determine, based on ephemeris information, the second satellite that is adjacent to the first satellite where the source NTN access network device is located and arrives at the location of the terminal device later, thereby determining to switch the terminal device to the target NTN access network device deployed on the second satellite.

[0130] When it is determined that a terminal device needs to be handed over from a source NTN access network device to a target NTN access network device, the source NTN access network device sends a cell handover request to the target NTN access network device. The cell handover request may instruct the target NTN access network device to hand over the terminal device to its second cell. The cell handover request may carry parameter information of the terminal device (e.g., supported frequency bands, modulation schemes, etc.) so that the target NTN access network device can allocate appropriate resources to the terminal device, such as PUSCH uplink resources. Of course, the cell handover request may also include other information; this is not limited here, and reference can be made to related technical implementations regarding cell handover requests.

[0131] In some implementations, the source NTN access network device can use the Xn interface to send a cell handover request to the target NTN access network device via an inter-satellite link or a feeder link. Of course, in this embodiment, there are no restrictions on how the cell handover request is sent, and it can be configured according to actual conditions. The aforementioned source NTN access network device can exemplarily be a source base station, and the aforementioned target NTN access network device can exemplarily be a target base station.

[0132] S602, the target NTN access network device configures time-based Conditional Handover (CHO) parameters and resource indication information for the terminal device.

[0133] After receiving a cell handover request, the target NTN access network device reserves uplink resources for the terminal device. These reserved uplink resources are uplink PUSCH resources, used to send a message indicating completion of the cell handover on the PUSCH. In one implementation, the uplink resources reserved for the terminal device can be indicated by both time-based conditional handover (CHO) parameters and resource indication information. After receiving the cell handover request, the target NTN access network device can configure the time-based CHO parameters and resource indication information for the terminal device, and then send these parameters and information to the source NTN access network device. This allows the terminal device to use the time-based CHO parameters and resource indication information to determine suitable uplink resources and send a message indicating completion of the cell handover using those resources.

[0134] The time-based conditional handover CHO parameter can include: conditional handover start time t1-Threshold and the first time domain length. The conditional handover start time is the time at which the terminal device can begin handover. It should be noted that the time described by this conditional handover start time is the absolute time starting from 00:00:00 on January 1, 1997, and the conditional handover start time is a moment after 00:00:00 on January 1, 1997. In one example, the parameter description for the conditional handover start time can be configured as the field shown in Figure 7A: t1-Threshold-r17INTEGER(0…549755813887). This field indicates that the data type of t1-Threshold is the integer INTEGER, with a value range of 0 to 549755813887. For example, if the current absolute time is 50000, the value of the conditional switch start time can be configured as 50010, and the field in the switch request response message can be represented as "t1-Threshold-r17INTEGER(0…549755813887),50010".

[0135] The first time domain length represents the effective duration of the conditional switch. The first time domain length can be represented by the duration. In one example, the parameter description for duration can be configured as the field shown in Figure 7A: duration-r17INTEGER(1…600). This field indicates that the data type of duration is the integer INTEGER, with a value range of 1 to 600. A value of 1 corresponds to a duration of 100ms, and a value of 2 corresponds to a duration of 200ms. For example, if the duration is 100ms, the value of duration can be configured as 1, and the field in the switch request response message can be represented as "duration-r17INTEGER(1…600), 1".

[0136] The conditional handover start time and duration can indicate the time-domain range [t1-Threshold, t1-Threshold+duration] of the resources allocated by the target NTN access network device for this handover to the terminal device. Within a first time-domain duration starting from the conditional handover start time, the UE is allowed to hand over from the source NTN access network device to the destination NTN access network device, i.e., from the first cell to the second cell. The resource location in the frequency domain can be referred to in the implementation methods described in related technologies.

[0137] The uplink resource indication information indicates the uplink resources in the time domain. This information explicitly indicates to the terminal device the location of the available PUSCH uplink resources in the time domain for this handover. In some implementations, the resource indication information can be a resource indication bitmap (grantBitmap). The resource indication bitmap can indicate the reservation status of uplink resources within a first time domain length. For example, the resource indication bitmap can include multiple bits, each bit corresponding to a resource block, or in other words, each bit corresponding to a resource allocation unit, and each bit indicates whether the corresponding resource allocation unit has reserved uplink resources for the terminal device in this handover. Specifically, the value of each bit can be 0 or 1, where 0 indicates that the corresponding resource allocation unit has not reserved uplink resources for the terminal device, and 1 indicates that the corresponding resource allocation unit has reserved uplink resources for the terminal device.

[0138] For example, referring to Figure 7B, the 100ms period starting from t1-Threshold is divided into multiple (e.g., 10) resource allocation units. Uplink resources are reserved for the terminal device in the 3rd, 6th, and 10th resource allocation units. The resource configuration within this 100ms period is represented by a 10-bit bitmap as {0010010001}. Referring to Figure 7C, the 100ms period starting from t1-Threshold is divided into multiple (e.g., 10) resource allocation units. Uplink resources are reserved for the terminal device in the 3rd, 4th, and 5th resource allocation units. The resource configuration within this 100ms period is represented by a 10-bit bitmap as {0011100000}. It should be understood that the number and interval of the reserved resource allocation units are merely illustrative examples and do not constitute any limitation on this application. In practical applications, the target NTN access network device can flexibly set the resource indication bitmap according to the scarcity of link resources and the remaining available resources.

[0139] It should be understood that the above example only uses 10 resource allocation units. In some implementations, the target NTN access network device can choose the granularity of resource allocation, dividing the uplink resources within the first time domain length into multiple resource allocation units based on the granularity. The number and size of the resource allocation units after division vary depending on the granularity. In one example, the granularity parameter can be configured as shown in Figure 7A: grantBitmap-r19CHOICE{}, where the granularity can be n10, n20, n50, n100, etc. Granularity n10 indicates division into 10 resource allocation units; for example, with a duration of 100ms, the time domain length of each resource allocation unit is 10ms. Granularity n20 indicates division into 20 resource allocation units, with the time domain length of each resource allocation unit being 5ms. Granularity n50 indicates division into 50 resource allocation units, with the time domain length of each resource allocation unit being 2ms. Granularity n100 indicates division into 100 resource allocation units, with the time domain length of each resource allocation unit being 1ms.

[0140] In practice, target NTN access network devices can consider factors such as duration, subcarrier spacing, and available resources to select an appropriate granularity. For example, when the duration is short, the granularity can be smaller, such as n10 or n20; when the duration is long, the granularity can be larger, such as n50 or n100. Similarly, when the subcarrier spacing is low (e.g., 15kHz), the granularity can be larger, such as n50; when the subcarrier spacing is high (e.g., 120kHz), the granularity can be smaller, such as n10. Furthermore, when resources are scarce, the resource allocation unit can be finer, and the granularity can be larger, such as n50 or n100; when resources are abundant, the granularity can be smaller, such as n10. By controlling the granularity of resource reservation, resource waste caused by uplink resource reservation can be reduced more effectively.

[0141] It should be noted that resource scheduling of the target NTN access network device is based on time slots. The duration of a single scheduling unit (slot) varies depending on the subcarrier spacing. For example, a scheduling unit is 1ms when the subcarrier spacing is 15kHz; 0.5ms when the subcarrier spacing is 30kHz; and 0.25ms when the subcarrier spacing is 60kHz. The aforementioned conditional handover start time t1-Threshold is an absolute time. The conditional handover start time t1-Threshold may not be aligned with the start time of the target NTN access network device's scheduling unit. In this case, the aforementioned resource indication bitmap grantBitmap refers to the resource indication bitmap of the target NTN access network device starting from the first scheduling unit after t1-Threshold; that is, the handover start time t1-Threshold is aligned backward with the scheduling unit.

[0142] For example, referring to FIG7D, a radio frame consists of 10 subframes, each with a duration of 1ms and numbered 0-9. When the subcarrier is 30kHz, one subframe consists of 2 time slots, and one scheduling unit (slot) is 0.5ms. When the conditional switching start time t1-Threshold corresponds to the first time slot of the second subframe of the fifth radio frame, the resource indication bitmap starts from the second time slot of the second subframe of the fifth radio frame. When the duration is 100ms and the granularity is n10, one resource allocation unit is 10ms. The first resource allocation unit includes a time-domain resource of 10ms length starting from the second time slot of the second subframe of the fifth radio frame.

[0143] In this embodiment of the application, after receiving a cell handover request, the target NTN access network device may also allocate other resources for cell handover to the terminal device, such as core network resources, etc., without limitation.

[0144] S603, the target NTN access network device sends a handover request response message to the source NTN access network device. Correspondingly, the source NTN access network device receives the handover request response message.

[0145] In this embodiment of the application, the handover request response message at least indicates the uplink resources reserved by the target NTN access network device for the terminal device. In some implementations, the handover request response message includes at least: time-based conditional handover CHO parameters configured for the terminal device and resource indication information of the uplink resources.

[0146] It should be understood that the handover request response message may also include other important information about the second cell access, such as the target cell identifier (physical cell identifier, PCI), access security parameters, etc.

[0147] In some implementations, the target NTN access network device can use the Xn interface to send a handover request response message via an inter-satellite link or a feeder link. Of course, in this embodiment, there are no restrictions on how uplink resource indications are sent to the source NTN access network device; configuration can be made according to actual circumstances.

[0148] S604, the source NTN access network device sends the first message to the terminal device. Correspondingly, the terminal device receives the first message.

[0149] The first message can instruct the terminal device to switch to the second cell, and can also indicate the uplink resources reserved by the target NTN access network device for the terminal device. In some implementations, the first message may include parameter information of the target NTN access network device, as well as time-based conditional handover CHO parameters and resource indication information configured by the target NTN access network device for the terminal device.

[0150] As an example, the first message could be an RRC reconfiguration message. The RRC reconfiguration message could include parameter information of the target NTN access network device, as well as time-based conditional handover CHO parameters and resource indication information configured by the target NTN access network device for the terminal device.

[0151] The parameter information of the target NTN access network device is used by the terminal device to access the target NTN access network device. This parameter information may include information related to cell handover and access from the System Information Block (SIB) of the target NTN access network device. For example, the parameter information of the target NTN access network device may include one or more of the following: the identifier of the second cell, signal beam configuration, cell-specific reference signal configuration, orbital parameters (orbit type, orbital inclination, orbital period, etc.) of the satellite where the target NTN access network device is located, time offset and position coordinates of the satellite where the target NTN access network device is located, service area identifier and service area shape of the second cell, cell reselection information, neighbor cell relationships, cell access restrictions, ephemeris information of the satellite where the target NTN access network device is located, etc. This parameter information facilitates the terminal device's access to the target NTN access network device.

[0152] Referring to the foregoing description, the time-based conditional handover parameters and uplink resource indication information enable the terminal device to use uplink resources to send a message indicating the completion of cell handover.

[0153] S605, the terminal device determines the uplink resources based on time-based conditional handover parameters and resource indication information.

[0154] After receiving the first message, the terminal device parses it to obtain time-based conditional handover parameters, uplink resource indication information, and parameter information of the target NTN access network device. When the current time reaches t1-Threshold, the terminal device begins accessing the second cell based on the first message. Specifically, when the current time reaches t1-Threshold, the terminal device can perform downlink synchronization based on the parameter information of the target NTN access network device and satellite ephemeris information to ensure that the terminal can accurately obtain the time and location data of the second satellite. After synchronization, the terminal device calculates the uplink timing advance (TA) based on the distance to the second satellite, propagation delay, and ephemeris information, etc., in order to send uplink messages in advance. It should be understood that downlink synchronization and TA calculation require a certain amount of time.

[0155] During cell handover, the terminal device needs to send a message indicating completion of cell handover to the target NTN access network device to complete the entire cell handover process and enable normal communication afterwards. When sending the message indicating completion of cell handover, the terminal device determines the nearest resource allocation unit after the current time based on the current time and the aforementioned resource indication bitmap, and sends the message indicating completion of cell handover to the nearest resource allocation unit.

[0156] For example, referring to Figure 7A, if the terminal device takes 18ms to complete its preparation, it can send a message indicating completion of cell handover on the third resource allocation unit. Since the terminal device does not require uplink resources during preparation, and the first and second resource allocation units have not reserved uplink resources, the resources reserved for the terminal device are not wasted. In some cases, after the terminal device sends the message indicating completion of cell handover on the third resource allocation unit, the subsequently reserved resources can be released and reallocated by the target NTN access network equipment.

[0157] For example, if the terminal device takes 40ms to complete its preparation, it can send a message indicating the completion of cell handover in the 6th resource allocation unit. Since there are multiple reserved uplink resources, if the terminal device misses an earlier resource allocation unit, it can find uplink resources in a later resource allocation unit within the first time domain length, thereby avoiding handover failure due to lack of uplink scheduling resources.

[0158] S606, the terminal device sends a second message to the target NTN access network device on the PUSCH according to the uplink resources. Correspondingly, the target NTN access network device receives the second message.

[0159] The second message indicates that the terminal device has completed cell handover. Corresponding to the first message from the source NTN access network device instructing the terminal device to perform cell handover is an RRC reconfiguration message, the second message can be an RRC reconfiguration completion message.

[0160] The terminal device indicates that the cell handover has been completed via a second message, which helps the target NTN access network device to determine that the terminal device has completed the cell handover so that normal communication can proceed normally afterwards.

[0161] In summary, the method provided in this application involves the target NTN access network device configuring time-based conditional handover CHO parameters and a resource indication bitmap (grantBitmap) for the terminal device during pre-handover negotiation; and including the time-based conditional handover CHO parameters and the resource indication bitmap (grantBitmap) in a handover request response message, which is then sent to the target NTN access network device; the source NTN access network device sending the time-based conditional handover CHO parameters and the resource indication bitmap (grantBitmap) configured by the target NTN access network device for the terminal device via a handover command RRC reconfiguration message (first message); the target NTN access network device reserving uplink PUSCH resources for the terminal device based on the time-based conditional handover CHO parameters and the resource indication bitmap (grantBitmap); and the terminal device sending an RRC reconfiguration completion message (second message) indicating handover completion based on the uplink resources indicated by the time-based conditional handover CHO parameters and the resource indication bitmap (grantBitmap), thus completing the cell handover process. In summary, by using time-based conditional switching of CHO parameters and resource indication bitmap grantBitmap, the target NTN access network device reserves uplink PUSCH resources for the terminal device and controls the granularity of resource reservation. When the terminal device is at the indicated reserved uplink resource location, it sends a message indicating completion of cell handover, which greatly reduces resource waste caused by uplink resource reservation and can also avoid handover failure due to the terminal device's lack of uplink scheduling.

[0162] The cell handover method provided in the embodiments of this application has been described above. The communication device for performing the above method provided in the embodiments of this application is described below.

[0163] Referring to Figure 8, which is a schematic diagram of the communication device provided in this application, the communication device 800 may include a communication unit 802 and optionally a processing unit 801. The communication unit 802 can implement corresponding communication functions, which can be internal communication within the communication device 800 or communication between the communication device 800 and other devices; the processing unit 801 can implement corresponding processing functions. The communication unit 802 may also be referred to as a communication interface or transceiver unit. Optionally, the communication device 800 may further include a storage unit, which can be used to store instructions and / or data. The processing unit 801 can read the instructions and / or data from the storage unit to enable the communication device 800 to implement the aforementioned method embodiments.

[0164] In one possible design, the communication device 800 may be the source NTN access network device in the above method embodiments, or a module or chip applied in the source NTN access network device. The communication device 800 can be used to execute the steps or processes performed by the source NTN access network device in the above embodiments.

[0165] Specifically, the processing unit 801 of the communication device 800 can be used to determine whether to switch the terminal device from the source NTN access network device to the target NTN access network device.

[0166] The communication unit 802 can be used to: send a cell handover request to the target NTN access network device when it is determined that the terminal device will be switched from the source NTN access network device to the target NTN access network device; receive a handover request response message sent by the target NTN access network device, the handover request response message including at least: time-based conditional handover parameters, and resource indication information for indicating uplink resources in the time domain, wherein the time-based conditional handover parameters include a first time domain length and a conditional handover start time, and the uplink resources are located within the first time domain length starting from the conditional handover start time.

[0167] In another possible design, the communication device 800 may be the target NTN access network device in the above method embodiments, or a module or chip applied in the target NTN access network device. The communication device 800 may be used to execute the steps or processes performed by the target NTN access network device in the above embodiments.

[0168] Specifically, the processing unit 801 of the communication device 800 can be used to: configure time-based conditional switching parameters for the terminal device, and to provide resource indication information for indicating uplink resources in the time domain.

[0169] The communication unit 802 can be used to: receive a cell handover request sent by the source NTN access network device; send a handover request response message to the source NTN access network device, the handover request response message including at least: time-based conditional handover parameters, and resource indication information for indicating uplink resources in the time domain, the time-based conditional handover parameters including a first time domain length and a conditional handover start time, the uplink resources being located within the first time domain length starting from the conditional handover start time.

[0170] The communication device 800 may be a terminal device as described in the above method embodiments, or a module or chip applied in a terminal device. The communication device 800 may be used to execute the steps or processes performed by the terminal device in the above embodiments.

[0171] Specifically, the communication unit 802 of the communication device 800 can be used to: receive a first message sent by the source NTN access network device, the first message instructing the terminal device to switch to the target NTN access network device, the first message including at least: time-based conditional handover parameters, and resource indication information for indicating uplink resources in the time domain, the time-based conditional handover parameters including a first time domain length and a conditional handover start time, the uplink resources being located within the first time domain length starting from the conditional handover start time; within the first time domain length, using the nearest uplink resource after the current time, send a second message to the target NTN access network device, the second message instructing the terminal device to complete the cell handover. The processing unit 801 can be used to: switch to the target NTN access network device.

[0172] For details regarding the steps or processes executed by each unit in the communication device 800, please refer to the above method embodiments; they will not be described in detail here.

[0173] It should be understood that the "unit" in the communication device 800 can be implemented in hardware, software, or by hardware executing corresponding software. For example, the "unit" can refer to an application-specific integrated circuit (ASIC), electronic circuitry, a processor (e.g., a shared processor, a proprietary processor, or a group processor) and memory for executing one or more software or firmware programs, combined logic circuitry, and / or other suitable components supporting the described functions. As another example, the communication unit 802 can be replaced by a transceiver circuit (e.g., it may include receiving and transmitting circuitry), and the processing unit 801 can be replaced by a processor or processing circuitry.

[0174] Referring to Figure 9, which is a schematic diagram of the structure of a communication device 900 applicable to an embodiment of this application. The communication device 900 can be a communication equipment, or a chip, chip system, or processor that supports the communication equipment in implementing the above methods. The communication equipment can be a terminal device or a network device. This device can be used to implement the methods described in the above method embodiments; for details, please refer to the descriptions in the above method embodiments.

[0175] The communication device 900 includes one or more processors 901, which can also be called processing units, and can perform certain control functions. The processor 901 can be a general-purpose processor or a special-purpose processor, etc.

[0176] In an alternative design, the processor 901 may also store instructions and / or data that can be executed by the processor 901 to cause the communication device 900 to perform the methods described in the above method embodiments.

[0177] Optionally, the communication device 900 may include one or more memories 902, which may store instructions that can be executed on the processor 901, causing the communication device 900 to perform the methods described in the above method embodiments. Optionally, the memories 902 may also store data. Optionally, the processor 901 may also store instructions and / or data. The processor 901 and the memories 902 may be provided separately or integrated together.

[0178] In another alternative design, the communication device 900 may include a communication interface 903 for implementing receiving and transmitting functions. For example, the communication interface 903 may be a transceiver circuit, interface, interface circuit, or transceiver. The transceiver circuit, interface, interface circuit, or transceiver for implementing receiving and transmitting functions may be separate or integrated. The aforementioned transceiver circuit, interface, interface circuit, or transceiver may be used for reading and writing code / data, or it may be used for transmitting or relaying signals.

[0179] Those skilled in the art will understand that, for ease of explanation, Figure 9 shows only one memory and processor. In actual devices, multiple processors and memories may exist. Memory may also be referred to as storage medium or storage device, etc., and the embodiments of this application do not impose such limitations.

[0180] It should be understood that, in one possible design, the steps in the method embodiments provided in this application can be implemented by integrated logic circuits in the processor's hardware or by instructions in software form. The steps of the methods disclosed in the embodiments of this application can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules in the processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, detailed descriptions are not provided here.

[0181] It should be noted that the processor in the embodiments of this application can be an integrated circuit chip with signal processing capabilities. In implementation, the steps of the above method embodiments can be completed by the integrated logic circuitry in the processor's hardware or by software instructions.

[0182] In the embodiments of this application, the processor can be a CPU, or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in the embodiments of this application can be directly manifested as execution by a hardware decoding processor, or execution by a combination of hardware and software modules in the decoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method.

[0183] It should be understood that, in the embodiments of this application, the memory may include read-only memory and random access memory, and provides instructions and data to the processor. The memory may also include non-volatile random access memory. The memory may be volatile memory or non-volatile memory, or may include both. The non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory may be random access memory (RAM), which serves 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 linked dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM).

[0184] This application provides a communication network, including at least one network device and multiple terminal devices. The network device is used to perform the steps performed by the network device in the method embodiment, and the terminal devices are used to perform the steps performed by the terminal devices in the method embodiment.

[0185] This application provides a computer storage medium that stores a computer program (also referred to as code or instructions) that, when run on a computer, causes the computer to perform the methods of this application.

[0186] This application provides a computer program product containing instructions, which includes a computer program (also referred to as code or instructions) that, when run, causes a computer to perform the method of this application embodiment.

[0187] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. This computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer program are loaded or executed on a computer, all or part of the processes or functions according to the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. A semiconductor medium can be a solid-state drive.

[0188] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0189] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0190] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0191] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0192] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0193] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0194] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for cell handover based on an NTN network, characterized in that, The NTN network includes a source NTN access network device and a target NTN access network device. The method is applied to the source NTN access network device, and the method includes: If it is determined that the terminal device will be switched from the source NTN access network device to the target NTN access network device, a cell handover request is sent to the target NTN access network device. The system receives a handover request response message from the target NTN access network device. The handover request response message includes at least: time-based conditional handover parameters and resource indication information for indicating uplink resources in the time domain. The time-based conditional handover parameters include a first time domain length and a conditional handover start time. The uplink resources are located within the first time domain length starting from the conditional handover start time.

2. The method according to claim 1, characterized in that, The resource indication information is a resource indication bitmap, which includes multiple bits. Each bit in the multiple bits corresponds to a resource allocation unit, and each bit indicates whether uplink resources are reserved in the corresponding resource allocation unit.

3. The method according to claim 1 or 2, characterized in that, The method further includes: A first message is sent to the terminal device, the first message instructing the terminal device to switch to the target NTN access network device, the first message including at least: the time-based conditional handover parameters, and the resource indication information for indicating uplink resources in the time domain.

4. The method according to claim 3, characterized in that, The first message is a Radio Resource Control Protocol (RRC) reconfiguration message.

5. The method according to any one of claims 1 to 4, characterized in that, Before sending a cell handover request to the target NTN access network device, the method further includes: The signal quality of the terminal device was detected to be less than a preset threshold. It is determined that the terminal device will be switched from the source NTN access network device to the target NTN access network device.

6. The method according to any one of claims 1 to 4, characterized in that, Before sending a cell handover request to the target NTN access network device, the method further includes: Based on the relative movement trajectory and relative movement speed of the terminal device relative to the source NTN access network device, it is predicted that the terminal device will leave the coverage area of ​​the source NTN access network device within a preset time period. It is determined that the terminal device will be switched from the source NTN access network device to the target NTN access network device.

7. A method for cell handover based on an NTN network, characterized in that, The NTN network includes a source NTN access network device and a target NTN access network device. The method is applied to the target NTN access network device, and the method includes: Received the cell handover request sent by the source NTN access network device; Configure time-based conditional switching parameters for the terminal device, and resource indication information for indicating uplink resources in the time domain; A handover request response message is sent to the source NTN access network device. The handover request response message includes at least: the time-based conditional handover parameters and the resource indication information for indicating uplink resources in the time domain. The time-based conditional handover parameters include a first time domain length and a conditional handover start time. The uplink resources are located within the first time domain length starting from the conditional handover start time.

8. The method according to claim 7, characterized in that, The resource indication information is a resource indication bitmap, which includes multiple bits. Each bit in the multiple bits corresponds to a resource allocation unit, and each bit indicates whether uplink resources are reserved in the corresponding resource allocation unit.

9. The method according to claim 8, characterized in that, The method further includes: Based on the resource indication bitmap, the uplink resources are reserved for the terminal device within the first time domain length.

10. The method according to claim 9, characterized in that, The resource indication bitmap is a bitmap indicating the resources of the target NTN access network device starting from the first scheduling unit after the condition handover start time.

11. The method according to any one of claims 8 to 10, characterized in that, The method further includes: Determine the granularity of resource allocation, with different granularities corresponding to different numbers of resource allocation units; Based on the granularity, the uplink resources are divided into multiple resource allocation units.

12. The method according to any one of claims 7 to 11, characterized in that, The method further includes: Upon receiving a second message, which was sent by the terminal device within the first time domain length via the uplink resources, the second message instructs the terminal device to complete cell handover.

13. The method according to claim 12, characterized in that, The second message is a Radio Resource Control (RRC) reconfiguration completion message.

14. A method for cell handover based on an NTN network, characterized in that, The NTN network includes source NTN access network equipment and target NTN access network equipment. The method is applied to a terminal device, and the method includes: Upon receiving a first message sent by the source NTN access network device, the first message instructs the terminal device to switch to the target NTN access network device. The first message includes at least: the time-based conditional handover parameters and the resource indication information for indicating uplink resources in the time domain. The time-based conditional handover parameters include a first time domain length and a conditional handover start time. The uplink resources are located within the first time domain length starting from the conditional handover start time. Within the first time domain length, a second message is sent to the target NTN access network device using the most recent uplink resource after the current time. The second message instructs the terminal device to complete cell handover.

15. The method according to claim 14, characterized in that, The resource indication information is a resource indication bitmap, which includes multiple bits. Each bit in the multiple bits corresponds to a resource allocation unit, and each bit indicates whether uplink resources are reserved in the corresponding resource allocation unit.

16. The method according to claim 14 or 15, characterized in that, The first message is a Radio Resource Control Protocol (RRC) reconfiguration message.

17. The method according to any one of claims 14 to 16, characterized in that, The second message is a Radio Resource Control (RRC) reconfiguration completion message.

18. A network device, characterized in that, include: Processor and memory; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the network device to perform the method as described in any one of claims 1-6, or the method as described in any one of claims 7-13.

19. A terminal device, characterized in that, include: Processor and memory; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the terminal device to perform the method as described in any one of claims 14-17.

20. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1-6, or any one of claims 7-13, or any one of claims 14-17.

21. A chip system, characterized in that, It includes at least one processor and a communication interface, the communication interface and the at least one processor being interconnected via a line, the at least one processor being configured to run a computer program or instructions to perform the method as claimed in any one of claims 1-6, or any one of claims 7-13, or any one of claims 14-17.

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