Switching method and device

Abstract

The embodiment of the invention provides a switching method and device. The method is executed by a terminal device or a chip applied to the terminal device, and the method comprises the steps of receiving CHO configuration information from a first network device, the CHO configuration information being used for the terminal device to access a first target cell under the condition that a first condition is satisfied, determining whether the first condition is satisfied in a first time unit, the first time unit is any time unit in a communication gap existing in a switching period of network equipment to which the source cell belongs, and accessing the first target cell under the condition that a first condition is met. In the embodiment of the invention, it is clear that the terminal equipment can evaluate the first condition in the communication gap existing in the switching period of the network equipment to which the source cell belongs, and since the terminal equipment possibly needs to access the first target cell after the network equipment to which the source cell belongs is switched, the terminal equipment can access the first target cell by evaluating the first condition in the communication gap in advance. The switching efficiency of the terminal equipment can be improved.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a switching method and device. Background Art

[0002] Non-terrestrial network (NTN) communication refers to communication achieved with the help of non-terrestrial network equipment. NTN systems can include satellite systems, etc. Introducing NTN communication into mobile network communication, such as the fifth-generation (5G) communication, can improve user experience. On the one hand, NTN can provide communication services for areas that are difficult to cover by terrestrial networks, such as oceans, forests, deserts or remote areas; on the other hand, NTN can enhance the reliability of mobile communications, such as providing more stable communication services for users in high-speed mobile scenarios such as trains and airplanes; in addition, NTN can also provide more data transmission resources and support the connection of a larger number of terminal devices.

[0003] In mobile communication networks, the movement of terminal devices will cause the signal quality of the current service cell to deteriorate, and it is necessary to switch to a neighboring cell with better signal quality. In the NTN system, the high-speed movement of non-terrestrial network devices relative to the ground makes the coverage duration of non-terrestrial network devices in a certain area on the ground very short, causing terminal devices to frequently change service cells. Therefore, in the NTN system, the mobility of non-terrestrial network devices is the main reason for terminal devices to switch cells.

[0004] Since the coverage area of ​​NTN cells is very large (coverage radius is tens to hundreds of kilometers), the number of terminal devices included in a cell is also very large, so the movement of non-terrestrial network devices will cause a large number of terminal devices to switch cells simultaneously or frequently. During the cell switching process, a large number of signaling interactions will be generated. Therefore, processing a large number of cell switching requests from terminal devices in a short period of time will cause network processing burden, and even cause signaling congestion and increased signaling overhead. Summary of the invention

[0005] The embodiments of the present application provide a switching method and apparatus for improving the switching efficiency of a terminal device.

[0006] In the first aspect, an embodiment of the present application provides a switching method, which can be executed by a terminal device or by a chip system, and the chip system can realize the functions of the terminal device. The method includes: receiving conditional handover (CHO) configuration information from a first network device, the first network device is a network device to which a source cell of the terminal device belongs, and the CHO configuration information is used for the terminal device to access a first target cell when a first condition is met; determining whether the first condition is met in a first time unit, the first time unit is any time unit in a communication gap existing during the switching of the network device to which the source cell belongs; and accessing the first target cell when the first condition is met.

[0007] In an embodiment of the present application, it is clear that when there is a communication gap during the switching of the network device to which the source cell belongs, the terminal device can evaluate the CHO execution condition (i.e., the first condition) in the communication gap. For example, the satellite of the source cell is switched from the first satellite to the second satellite, and there is no overlap in the service time when the first satellite and the second satellite provide services to the source cell. There will be a communication gap during the switching of the first satellite and the second satellite, and the terminal device can evaluate the CHO execution condition in the communication gap. Since the terminal device may move out of the coverage of the source cell or the coverage of the first satellite and the second satellite may be inconsistent after the switching of the first satellite and the second satellite, the terminal device needs to execute CHO (i.e., access the first target cell). By evaluating the CHO execution condition in advance in the communication gap, the switching efficiency of the terminal device can be improved.

[0008] In an optional implementation, the first condition includes one or more of the following: an execution condition based on time; an execution condition based on distance; or an execution condition based on signal quality. In this implementation, since the terminal device cannot obtain the signal quality of the source cell during the communication gap during the switching of the network device to which the source cell belongs, and thus cannot evaluate the execution condition based on signal quality, the CHO execution condition may only include an execution condition based on time and / or distance, thereby reducing the impact of the communication gap on the evaluation of the CHO execution condition, so that the terminal device can evaluate the CHO execution condition in the communication gap.

[0009] In an optional implementation, the time-based execution condition includes a time window. For example, the first network device sets a time window (T1, T2) for the terminal to configure CHO execution (i.e., access to the first target cell), and the terminal device can execute CHO within the time window (T1, T2).

[0010] In an optional implementation, the distance-based execution condition includes a distance threshold. For example, the first network device configures a distance threshold D1 and a distance threshold D2 for the terminal device to execute CHO (i.e., access the first target cell). If the distance from the terminal device to the first target cell is less than the distance threshold D1, and the distance from the terminal device to the source cell is greater than the distance threshold D2, the terminal device can execute CHO.

[0011] In an optional implementation, the execution condition based on signal quality includes one or more of the A3 event, the A4 event, or the A5 event. In this implementation, since the terminal device cannot obtain the signal quality of the source cell during the communication gap existing during the switching of the network device to which the source cell belongs, and thus cannot evaluate the A3 event or the A5 event, the execution condition based on signal quality may only include the A4 event, thereby reducing the impact of the communication gap on the evaluation of the execution condition based on signal quality, so that the terminal device can evaluate the execution condition based on signal quality during the communication gap.

[0012] In an optional embodiment, the method further includes: determining whether the A3 event or the A5 event is satisfied based on a first signal quality of the source cell, the first signal quality being the signal quality of the source cell before the time when the first network device stops covering the area where the terminal device is located, or when the first network device stops covering the area where the terminal device is located; or, determining whether the A3 event or the A5 event is satisfied based on a second signal quality of the source cell, the second signal quality being a default value. In this embodiment, the terminal device can evaluate the A3 event or the A5 event based on the signal quality of the source cell before or when the terminal device is disconnected from the source cell or the default value, thereby reducing the impact of the communication gap on the evaluation of the A3 event or the A5 event, so that the terminal device can evaluate the A3 event or the A5 event during the communication gap.

[0013] In an optional implementation, the method further includes: when the first condition is not met, accessing a second target cell, the second target cell configuring a dedicated random access resource for the terminal device. In this implementation, if the first condition is not met, the terminal device may choose not to access the first target cell, but to access the second target cell configuring a dedicated random access resource for the terminal device, thereby improving the switching efficiency of the terminal device.

[0014] In an optional embodiment, the method further includes: receiving a physical cell identifier (PCI) unchanged switching indication information from the first network device, the PCI unchanged switching indication information being used to instruct the terminal device to access the second network device when a second condition is met; and access the second network device when the first condition is not met but the second condition is met. In this embodiment, if the first condition is not met and the terminal device has configured PCI unchanged switching, the terminal device may choose not to access the first target cell but to access the second network device, i.e., choose to perform PCI unchanged switching, thereby improving the switching efficiency of the terminal device.

[0015] In an optional implementation, the second condition includes one or more of the following: the time when the first network device stops covering the area where the terminal device is located; the time when the PCI unchanged switching takes effect; the time when the second network device performs downlink synchronization with the terminal device; or the time when the second network device starts covering the area where the terminal device is located. In this implementation, the terminal device can perform the PCI unchanged switching at the above multiple times, and the switching method is more flexible.

[0016] In an optional implementation, the method further includes: when the communication gap is greater than a first threshold, determining whether the first condition is satisfied in the first time unit. In this implementation, since the communication gap existing during the switching of the network device to which the terminal device cell belongs cannot obtain the signal quality of the source cell, the terminal device can determine whether to evaluate the first condition in the communication gap according to the size of the communication gap. If the communication gap is large, the terminal device will evaluate the first condition in the communication gap. If the communication gap is small, the terminal device can evaluate the first condition after the communication gap to reduce the impact of the communication gap on the evaluation of the first condition.

[0017] In a second aspect, an embodiment of the present application further provides a switching method, which can be executed by a first network device, or by a chip system, which can implement the functions of the first network device. The method includes: sending CHO configuration information to a terminal device, wherein the CHO configuration information is used for the terminal device to access a first target cell when a first condition is met, wherein the first condition includes one or more of the following: an execution condition based on time; an execution condition based on distance; or an execution condition based on signal quality.

[0018] In an optional implementation, the time-based execution condition includes a time window.

[0019] In an optional implementation, the distance-based execution condition includes a distance threshold.

[0020] In an optional implementation, the execution condition based on signal quality includes one or more of A3 events, A4 events, or A5 events.

[0021] In an optional embodiment, the method also includes: determining whether the A3 event or the A5 event is satisfied based on a first signal quality of a source cell of the terminal device, the first signal quality being the signal quality of the source cell before the time when the first network device stops covering the area where the terminal device is located, or when the first network device stops covering the area where the terminal device is located; or, determining whether the A3 event or the A5 event is satisfied based on a second signal quality of the source cell of the terminal device, the second signal quality being a default value.

[0022] Regarding the technical effects brought about by the second aspect or some optional implementation methods, reference may be made to the introduction to the technical effects of the first aspect or corresponding implementation methods.

[0023] In a third aspect, an embodiment of the present application further provides a switching method, which can be executed by a terminal device or by a chip system, and the chip system can realize the functions of the terminal device. The method includes: receiving CHO configuration information and PCI unchanged switching indication information from a first network device, the first network device is a network device to which a source cell of the terminal device belongs, the CHO configuration information is used for the terminal device to access a first target cell when a first condition is met, and the PCI unchanged switching indication information is used to indicate that the terminal device accesses a second network device when a second condition is met; when the first condition and the second condition are met, access the first target cell or access the second network device.

[0024] In the embodiments of the present application, it is clarified that when the terminal device is configured with CHO and PCI unchanged switching, the terminal device can choose to execute CHO (i.e., access the first target cell) or PCI unchanged switching (i.e., access the second network device) when both the CHO execution condition (i.e., the first condition) and the PCI unchanged switching execution condition (i.e., the second condition) are met, thereby clarifying the switching strategy of the terminal device and improving the switching efficiency of the terminal device.

[0025] In an optional implementation, the first condition includes one or more of the following: an execution condition based on time; an execution condition based on distance; or an execution condition based on signal quality. In this implementation, since the terminal device cannot obtain the signal quality of the source cell during the communication gap during the switching of the network device to which the source cell belongs, and thus cannot evaluate the execution condition based on signal quality, the CHO execution condition may only include an execution condition based on time and / or distance, thereby reducing the impact of the communication gap on the evaluation of the CHO execution condition, so that the terminal device can evaluate the CHO execution condition in the communication gap.

[0026] In an optional implementation, the time-based execution condition includes a time window. For example, the first network device sets a time window (T1, T2) for the terminal to configure CHO execution (i.e., access to the first target cell), and the terminal device can execute CHO within the time window (T1, T2).

[0027] In an optional implementation, the distance-based execution condition includes a distance threshold. For example, the first network device configures a distance threshold D1 and a distance threshold D2 for the terminal device to execute CHO (i.e., access the first target cell). If the distance from the terminal device to the first target cell is less than the distance threshold D1, and the distance from the terminal device to the source cell is greater than the distance threshold D2, the terminal device can execute CHO.

[0028] In an optional implementation, the execution condition based on signal quality includes one or more of the A3 event, the A4 event, or the A5 event. In this implementation, since the terminal device cannot obtain the signal quality of the source cell during the communication gap existing during the switching of the network device to which the source cell belongs, and thus cannot evaluate the A3 event or the A5 event, the execution condition based on signal quality may only include the A4 event, thereby reducing the impact of the communication gap on the evaluation of the execution condition based on signal quality, so that the terminal device can evaluate the execution condition based on signal quality during the communication gap.

[0029] In an optional embodiment, the method further includes: determining whether the A3 event or the A5 event is satisfied based on a first signal quality of the source cell, the first signal quality being the signal quality of the source cell before the time when the first network device stops covering the area where the terminal device is located, or when the first network device stops covering the area where the terminal device is located; or, determining whether the A3 event or the A5 event is satisfied based on a second signal quality of the source cell, the second signal quality being a default value. In this embodiment, the terminal device can evaluate the A3 event or the A5 event based on the signal quality of the source cell before or when the terminal device is disconnected from the source cell or the default value, thereby reducing the impact of the communication gap on the evaluation of the A3 event or the A5 event, so that the terminal device can evaluate the A3 event or the A5 event during the communication gap.

[0030] In an optional implementation, the second condition includes one or more of the following: the time when the first network device stops covering the area where the terminal device is located; the time when the PCI unchanged switching takes effect; the time when the second network device performs downlink synchronization with the terminal device; or the time when the second network device starts covering the area where the terminal device is located. In this implementation, the terminal device can perform the PCI unchanged switching at the above multiple times, and the switching method is more flexible.

[0031] In an optional embodiment, the method also includes: accessing the first target cell when the first condition, the second condition and the third condition are met; wherein the third condition includes one or more of the following: the time when the third network device stops covering the area where the terminal device is located is later than the time when the second network device stops covering the area where the terminal device is located, and the third network device is the network device to which the first target cell belongs; the first target cell configures dedicated random access resources for the terminal device; or the distance between the first target cell reference point and the terminal device is less than the distance between the source cell reference point and the terminal device.

[0032] In this implementation, if both the CHO execution condition (i.e., the first condition) and the PCI unchanged switching execution condition (i.e., the second condition) are met, the selection of executing either CHO (i.e., accessing the first target cell) or PCI unchanged switching (i.e., accessing the second network device) is performed based on information such as the service outage time of the network device to which the first target cell or the source cell belongs, whether the first target cell or the source cell is configured with dedicated random access resources for the terminal device, or the distance between the first target cell or the source cell and the terminal device, thereby clarifying the switching strategy of the terminal device and improving the switching efficiency of the terminal device.

[0033] In an optional embodiment, the method also includes: accessing the second network device when the first condition, the second condition and the fourth condition are met; wherein the fourth condition includes one or more of the following: the time when the second network device stops covering the area where the terminal device is located is later than the time when the third network device stops covering the area where the terminal device is located, and the third network device is the network device to which the first target cell belongs; the source cell configures dedicated random access resources for the terminal device; or the distance between the source cell reference point and the terminal device is less than the distance between the first target cell reference point and the terminal device.

[0034] In this implementation, if both the CHO execution condition (i.e., the first condition) and the PCI unchanged switching execution condition (i.e., the second condition) are met, the selection of executing either CHO (i.e., accessing the first target cell) or PCI unchanged switching (i.e., accessing the second network device) is based on information such as the service outage time of the network device to which the first target cell or the source cell belongs, whether the first target cell or the source cell is configured with dedicated random access resources for the terminal device, or the distance between the first target cell or the source cell and the terminal device, thereby clarifying the switching strategy of the terminal device and improving the switching efficiency of the terminal device.

[0035] In a fourth aspect, an embodiment of the present application further provides a switching method, which can be executed by a first network device, or by a chip system, and the chip system can implement the functions of the first network device. The method includes: sending CHO configuration information and PCI unchanged switching indication information to a terminal device, wherein the CHO configuration information is used for the terminal device to access the first target cell when a first condition is met, and the PCI unchanged switching indication information is used to indicate that the terminal device accesses the second network device when a second condition is met, wherein the first condition includes one or more of the following: an execution condition based on time; an execution condition based on distance; or an execution condition based on signal quality.

[0036] In an optional implementation, the time-based execution condition includes a time window.

[0037] In an optional implementation, the distance-based execution condition includes a distance threshold.

[0038] In an optional implementation, the execution condition based on signal quality includes one or more of A3 events, A4 events, or A5 events.

[0039] In an optional embodiment, the method also includes: determining whether the A3 event or the A5 event is satisfied based on a first signal quality of a source cell of the terminal device, the first signal quality being the signal quality of the source cell before the time when the first network device stops covering the area where the terminal device is located, or when the first network device stops covering the area where the terminal device is located; or, determining whether the A3 event or the A5 event is satisfied based on a second signal quality of the source cell of the terminal device, the second signal quality being a default value.

[0040] In an optional embodiment, the second condition includes one or more of the following: the time when the first network device stops covering the area where the terminal device is located; the time when the PCI unchanged switching takes effect; the time when the second network device performs downlink synchronization with the terminal device; or the time when the second network device starts to cover the area where the terminal device is located.

[0041] Regarding the technical effects brought about by the fourth aspect or some optional implementation methods, reference may be made to the introduction to the technical effects of the third aspect or corresponding implementation methods.

[0042] In a fifth aspect, an embodiment of the present application provides a communication device, including a processor and a memory; the memory is used to store computer instructions, and when the device is running, the processor executes the computer instructions stored in the memory to enable the device to execute any implementation method in the first to fourth aspects above. The memory can be a volatile or non-volatile memory, such as a cache in a semiconductor chip.

[0043] In a sixth aspect, an embodiment of the present application provides a communication device, which may be a terminal device or a first network device, or a chip for a terminal device or a first network device. The device has the function of implementing any implementation method of the first to fourth aspects above. The function may be implemented by hardware, or by hardware executing corresponding software implementation. The hardware or software includes one or more modules corresponding to the above functions.

[0044] In a seventh aspect, an embodiment of the present application provides a communication device, comprising a unit or means for executing each step of any implementation method in the first to fourth aspects above.

[0045] In an eighth aspect, an embodiment of the present application provides a communication device, including a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and execute any implementation method in the first to fourth aspects above. The processor may be one or more processors.

[0046] In a ninth aspect, an embodiment of the present application provides a communication device, comprising a processor coupled to a memory, the processor being used to call a program stored in the memory to execute any implementation method in the first to fourth aspects above. The memory may be located inside the device or outside the device. The processor may also be one or more processors.

[0047] In the tenth aspect, an embodiment of the present application further provides a computer-readable storage medium, wherein instructions are stored in the computer-readable storage medium, which, when executed on a communication device, enables any implementation method in the above-mentioned first to fourth aspects to be executed.

[0048] In the eleventh aspect, an embodiment of the present application further provides a computer program product, which includes a computer program or instructions. When the computer program or instructions are executed by a communication device, any implementation method in the above-mentioned first to fourth aspects is executed.

[0049] In the twelfth aspect, an embodiment of the present application also provides a chip system, including: a processor, used to execute any implementation method in the above-mentioned first to fourth aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A schematic diagram of an NTN system provided in an embodiment of the present application;

[0051] Figure 2 A schematic diagram of another NTN system provided in an embodiment of the present application;

[0052] Figure 3 A schematic diagram of the structure of an access network device provided in an embodiment of the present application;

[0053] Figure 4 A schematic diagram of a cell switching process provided in an embodiment of the present application;

[0054] Figure 5 A schematic diagram of a conditional switching process provided in an embodiment of the present application;

[0055] Figure 6 A schematic diagram of a geostationary cell provided in an embodiment of the present application;

[0056] Figure 7 A schematic diagram of a ground mobile cell provided in an embodiment of the present application;

[0057] Figure 8 A schematic diagram of a switching scenario provided in an embodiment of the present application;

[0058] Fig. 9 A schematic diagram of a switching method flow chart provided in an embodiment of the present application;

[0059] Fig.10 A schematic diagram of the structure of a communication device provided in an embodiment of the present application;

[0060] Fig.11 A schematic diagram of the structure of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0061] The embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0062] The switching method provided in the embodiment of the present application can be applied to the NTN system. The NTN system can use non-ground network devices such as drones, high altitude platform stations (HAPS), satellites, etc. to form a network and provide data transmission, voice communication and other services for terminal devices. In addition, the NTN system can also include other non-ground network devices, which are not limited in the present application.

[0063] The NTN system can also support various mobile communication systems, such as: new radio (NR) system, long term evolution (LTE) system or other communication systems such as future communication systems, but the specific ones are not limited here.

[0064] Taking satellites as an example of non-terrestrial network equipment in the NTN system, according to the satellite altitude, that is, the orbital altitude of the satellite, satellites can be divided into geostationary earth orbit (GEO) satellites, medium earth orbit (MEO) satellites and low-earth orbit (LEO) satellites. GEO is a synchronous earth satellite orbit. Satellites operating in this orbit are stationary relative to the ground. The orbital altitude of GEO is generally 35786 kilometers (km). LEO and MEO are collectively referred to as non-geostationary orbits (NGSO). Satellites operating in such orbits move at high speed relative to the ground. Among them, the orbital altitude of LEO is generally 160 to 2000 km, and the orbital altitude of MEO is generally 2000 to 35786 km. For NGSO, according to whether the satellite's beam moves with the satellite, it can be further divided into earth moving cells and geostationary cells (earth fixed cells or quasi-Earth fixed cells). For earth moving cells, the cell moves relative to the ground, and the satellite's beam pointing follows the satellite's movement. For earth fixed cells or quasi-Earth fixed cells, the cell is fixed relative to the ground for a certain period of time, and the satellite antenna can use its beamforming capability to point the beam to a certain area fixed on the ground for a certain period of time.

[0065] In the NTN system, the working modes of the NTN equipment may include: transparent mode and regenerative mode. According to the working mode of the NTN equipment, the architecture of the NTN system can be divided into the following two categories: one is the transparent forwarding architecture, in which the NTN equipment can be a relay or amplifier, and can perform RF filtering, amplification, etc., to regenerate the physical layer signal. The NTN equipment can be responsible for layer 1 (layer1, L1) relay, which is used for physical layer forwarding, and the upper layer is invisible. The second is the regenerative architecture, in which the NTN equipment has the processing function of the access network equipment. Exemplarily, the satellite in the regenerative working mode can be divided into a regenerative satellite without an intersatellite link, that is, there is no intersatellite link (ISL) between satellites; or a regenerative satellite with an intersatellite link, that is, there is an interface between satellites to directly exchange data, where the intersatellite link is an Xn port; or a regenerative satellite with a distributed unit (DU) processing function of an access network device, in which the satellite acts as a DU.

[0066] For example, Figure 1 A schematic diagram of an NTN system applicable to the embodiment of the present application is shown, and the NTN system may be a transparent forwarding architecture. Figure 1 In the system shown, the terminal device can communicate with the 5G core network (CN) through the access network, and then connect to the data network (DN) through the 5G CN. The satellite and NTN gateway can act as a relay device between the terminal device and the base station or as a remote radio unit (RRU) of the base station.

[0067] For example, Figure 2 Another NTN system schematic diagram applicable to the embodiment of the present application is shown, and the NTN system may be a regenerative architecture. Figure 2 In the system shown, the satellite can be used as a base station to form an access network with the NTN gateway, and communicate with the 5G CN through the NTN gateway, and then connect to the DN through the 5G CN. In addition, the satellite can also provide wireless access services for terminal devices. Figure 2 A regenerative satellite architecture without intersatellite links is illustrated.

[0068] It should be noted that Figure 1 and Figure 2Only one satellite and one NTN gateway are shown. In actual use, a plurality of satellites and / or a plurality of NTN gateways may be used as required. Each satellite may provide services to one or more terminal devices, each NTN gateway may correspond to one or more satellites, and each satellite may correspond to one or more NTN gateways, which are not specifically limited in the embodiments of the present application.

[0069] It should be noted that Figure 1 and Figure 2 This is only an example of the NTN system. The NTN system may also include other specific systems, which is not limited in this application.

[0070] The devices involved in the embodiments of the present application include terminal devices and network devices, and the network devices include, for example, terrestrial network (TN) devices (such as access network devices) and non-terrestrial network devices (such as satellites).

[0071] Terminal equipment, also known as user equipment (UE), mobile station (MS), mobile terminal (MT), etc., refers to equipment that provides voice and / or data connectivity to users. For example, the terminal equipment may be a handheld device, a vehicle-mounted device, etc. with a wireless connection function. At present, some examples of terminal equipment may be: mobile phones, tablet computers, laptop computers, PDAs, mobile internet devices (MID), wearable devices, virtual reality (VR) devices, augmented reality (AR) devices, wireless terminals in industrial control, wireless terminals in self driving, wireless terminals in remote medical surgery, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, etc.

[0072] The access network device may refer to a radio access network (RAN) node (or device) that connects a terminal device to a wireless network, such as a base station. Some examples of RAN nodes may include: a gNB, a transmission reception point (TRP), an evolved NodeB (eNB), a radio network controller (RNC), a NodeB (NB), a base station controller (BSC), a base transceiver station (BTS), a home evolved NodeB (e.g., home NodeB, or home NodeB, HNB), a base band unit (BBU), or a wireless fidelity (Wifi) access point (AP).

[0073] In addition, in a network structure, the access network device may include a centralized unit (CU) node, a distributed unit (DU) node, or a CU node and a DU node. The RAN device including the CU node and the DU node splits the protocol layer of the gNB in ​​the NR system, places the functions of some protocol layers in the CU for centralized control, and distributes the functions of the remaining part or all of the protocol layers in the DU, which is centrally controlled by the CU, such as Figure 3As shown. Furthermore, CU can also be divided into control plane (CU-CP) and user plane (CU-UP). CU-CP is responsible for control plane functions, mainly including radio resource control (RRC) and packet data convergence protocol (PDCP) (i.e. PDCP-C) corresponding to the control plane. PDCP-C is mainly responsible for encryption and decryption, integrity protection, data transmission, etc. of control plane data. CU-UP is responsible for user plane functions, mainly including service data adaptation protocol (SDAP) and PDCP corresponding to the user plane (i.e. PDCP-U). SDAP is mainly responsible for processing the data of the core network and mapping the flow to the bearer. PDCP-U is mainly responsible for encryption and decryption, integrity protection, header compression, sequence number maintenance, data transmission, etc. of the data plane. CU-CP and CU-UP are connected through the E1 interface. CU-CP represents that gNB is connected to the core network through the NG interface, and is connected to DU through the F1 interface control plane (i.e. F1-C). CU-UP is connected to DU via F1 interface user plane (i.e. F1-U). Of course, another possible implementation is that PDCP-C is also in CU-UP.

[0074] It can be understood that in different systems, CU (including CU-CP or CU-UP) or DU may have different names, but those skilled in the art can understand their meanings. For example, in an open radio access network (O-RAN) system, CU may also be referred to as O-CU (open CU), DU may also be referred to as O-DU, CU-CP may also be referred to as O-CU-CP, and CU-UP may also be referred to as O-CU-UP. For the convenience of description, this application takes CU, CU-CP, CU-UP and DU as examples for description.

[0075] In the embodiments of the present application, the communication device for realizing the function of the network device or the terminal device may be the network device or the terminal device itself, or may be a device capable of supporting the network device or the terminal device to realize the function, such as a chip system, which may be installed in the network device or the terminal device. In the technical solution provided in the embodiments of the present application, the technical solution provided in the embodiments of the present application is described by taking the device for realizing the function of the network device as the network device and the device for realizing the function of the terminal device as the terminal device as an example.

[0076] In the embodiments of the present application, the number of nouns, unless otherwise specified, means "singular noun or plural noun", that is, "one or more". "At least one" means one or more, and "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. For example, A / B means: A or B. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of singular or plural items.

[0077] The ordinal numbers such as "first" and "second" mentioned in the embodiments of the present application are used to distinguish multiple objects, and are not used to limit the size, content, order, timing, priority or importance of the multiple objects. For example, the first network device and the second network device can be the same network device or different network devices, and such names do not indicate the difference in priority or importance of the two network devices.

[0078] The above briefly introduces the communication system to which the embodiments of the present application are applicable. The following introduces the relevant technical solutions involved in the embodiments of the present application.

[0079] 1) Cell switching

[0080] In the TN system, the movement of the terminal device will cause the signal quality of the current service cell to deteriorate, and it is necessary to switch to a neighboring cell with better signal quality. It can be understood that due to the movement of the terminal device, the terminal device that is using the network service may move from a cell (source cell) provided by the base station to another cell (target cell) for the terminal device. In order to ensure communication continuity and service quality, it is necessary to transfer the communication link between the terminal device and the source cell to the target cell. The process of transferring the communication link between the terminal device and the source cell to the target cell is also called the cell switching process.

[0081] See also Figure 4 , which is a schematic diagram of the cell switching process. Figure 4 Take the case where the source cell is the cell of the source base station and the target cell is the cell of the target base station as an example. Cell switching includes the following steps:

[0082] Step 1: The source base station sends a measurement configuration message to the terminal device, so that the terminal device receives the measurement configuration message.

[0083] The measurement configuration message may include a measurement object, a cell list, a reporting method, etc. After receiving the measurement configuration message, the terminal device may measure the neighboring cell according to the measurement configuration message to obtain a measurement report (measurement reporting).

[0084] Step 2: The terminal device sends a measurement report to the source base station.

[0085] The measurement report may include the reference signal reception power of the serving cell, the signal reception power or signal quality of the neighboring cell, etc., so that the source base station can determine whether the terminal device performs cell switching based on the measurement report.

[0086] Among them, step 1 and step 2 are optional steps.

[0087] Step 3: The source base station determines a handover decision for the terminal device based on the measurement report.

[0088] The handover decision refers to deciding whether the terminal device performs a cell handover. If the terminal device needs to perform a cell handover, the source base station may send a handover request message to the target base station.

[0089] Optionally, the source base station may also determine the switching decision of the terminal device based on other content.

[0090] Step 4: The source base station sends a handover request message to the target base station.

[0091] The base station determines that the terminal device needs to switch cells according to the measurement report, and sends a switching request message to the target base station. The switching request message is used to request switching cells.

[0092] Step 5: The target base station sends a handover response message to the source base station. The handover response message may include configuration information of the target base station.

[0093] The configuration information of the target base station can be used for the terminal device to access the target base station.

[0094] Step 6: The source base station sends a switching command to the terminal device.

[0095] The handover command is used to instruct the terminal device to perform a cell handover. The terminal device receives the handover command in the source cell and parses the handover command to obtain the configuration information of the target cell, that is, the configuration of the terminal device in the target cell is obtained, so that the terminal device can switch to the target cell according to the configuration.

[0096] Step 7: The terminal device requests random access to the target base station.

[0097] 2) Conditional handover (CHO)

[0098] In order to avoid further deterioration of the communication link quality between the terminal device and the source base station, resulting in the inability to normally interact signaling between the terminal device and the source base station, thereby causing the cell switching to fail to be successfully executed, the prior art proposes a CHO mechanism. Specifically, when the communication link quality with the terminal device is good, the source base station sends CHO configuration information to the terminal device, and the CHO configuration information includes CHO execution conditions and candidate cell information (such as the global cell identification code (cellglobal identifier, CGI) of the candidate cell, or the physical cell identifier (physical cell identifier, PCI) of the candidate cell and the frequency information corresponding to the candidate cell). After receiving the configuration information, the terminal device determines whether the candidate cell meets the CHO execution conditions according to the configuration information, and takes a candidate cell that meets the CHO execution conditions as the target cell. Then, the terminal device initiates access to the target cell, such as initiating random access. After the random access is successful, the terminal device sends an RRC reconfiguration completion (RRCReconfigurationComplete) message to the base station to which the target cell belongs (i.e., the target base station) to notify the target base station that the CHO is completed.

[0099] See also Figure 5 , which is a flowchart of conditional switching. Figure 5 Take the case where the source cell is the cell of the source base station and the target cell is the cell of the target base station as an example. The conditional switching includes the following steps:

[0100] Step 1: The source base station sends an RRC reconfiguration (RRCRecofigureration) message to the terminal device.

[0101] The RRC reconfiguration message may include measurement configuration information. The measurement configuration information may include a measurement object, a cell list, a reporting method, etc. After receiving the RRC reconfiguration message, the terminal device may measure the neighboring cell according to the measurement configuration information to obtain a measurement report.

[0102] Step 2: The terminal device sends a measurement report to the source base station.

[0103] The measurement report may include the reference signal reception power of the serving cell, the signal reception power or signal quality of the neighboring cell, etc., so that the source base station can determine whether the terminal device performs cell switching based on the measurement report.

[0104] Among them, step 1 and step 2 are optional steps.

[0105] Step 3: The source base station determines a candidate cell according to the measurement report and sends a CHO request message to the candidate base station.

[0106] Optionally, the source base station may also determine the candidate cell according to other contents.

[0107] Step 4: The candidate base station sends a CHO request response message to the source base station.

[0108] The CHO request response message may include information of candidate cells.

[0109] Step 5: The source base station sends CHO configuration information to the terminal device.

[0110] The CHO configuration information may include CHO execution conditions and information of candidate cells.

[0111] Step 6: The terminal device determines whether the CHO execution condition is met, while maintaining the connection with the source base station. If a candidate cell meets the corresponding CHO execution condition, the candidate cell is determined to be the target cell.

[0112] Step 7: The terminal device accesses the target base station.

[0113] For example, the terminal device requests random access to the target base station.

[0114] Step 8: The terminal device sends an RRC reconfiguration completion message to the target base station.

[0115] 3) PCI unchanged switching (satellite switching while cell PCI unchanged, or called satellite switching resynchronization)

[0116] Unlike TN systems, in NTN systems, the mobility of non-terrestrial network equipment will cause a large number of terminal devices to need cell switching at the same time. Figure 6 As shown in the figure, for the geostationary cell, within a certain period of time, the satellite moves from position 1 to position 2, and the cell does not move with the satellite. When the satellite moves out of the coverage of the cell (or moves to a point where it cannot provide coverage for the cell), all the terminal devices in the cell need to switch to the next satellite. In this scenario, the simultaneous cell switching of a large number of terminal devices will lead to a signaling storm and cause signaling congestion. Figure 7 As shown, for the above-mentioned ground mobile cell, the cell moves with the non-ground network device, and terminal devices are constantly switched in / out during the movement of the non-ground network device. For example, the dotted cell represents the cell position when the satellite is at position 1, and the solid cell represents the cell position when the satellite is at position 2. The two partially overlap, and the terminal devices outside the overlapping area in the dotted cell need to be switched. Therefore, in this scenario, frequent cell switching of a large number of terminal devices will also lead to a large signaling overhead.

[0117] Since for geostationary cells, the base station remains unchanged before and after the satellite switching, and the satellite only performs the function of signal amplification, it is not necessary to change the PCI and frequency of the cell before and after the satellite switching. For example, the frequency of the synchronization signal and physical broadcast channel block (SSB) corresponding to the cell does not need to be changed, nor does it need to introduce Layer 3 (L3) signaling. The L3 signaling is used to notify the terminal device to switch. The terminal device only needs to re-synchronize the downlink and uplink with the new satellite after the new satellite arrives. For example, the uplink synchronization with the new satellite can be completed through random access, or the uplink synchronization with the new satellite can be completed through random access (random access channel less, rach less). That is, before and after the satellite switching, the configuration of the terminal device in the cell remains unchanged. Since there is no need to introduce L3 signaling for switching, the above-mentioned signaling congestion problem is solved.

[0118] Currently, satellite switching includes two switching modes: hard switching, that is, there is no overlap in the coverage time of the new and old satellites; soft switching, that is, there is overlap in the coverage time of the new and old satellites. For the hard switching scenario, the PCI of the cell can be unchanged before and after the satellite switching, and thus there is no need to issue a switching command. For the soft switching scenario, since there is overlap in the coverage time of the new and old satellites, there may be signal interference. Two solutions are proposed. One solution is to maintain the same solution as the hard switching scenario, and RAN1 will solve the signal interference; the other solution is to change the PCI of the cell before and after the satellite switching, but keep the configuration of the terminal device unchanged or slightly changed (for example, modify the configuration that is strongly related to the PCI of the cell, or only modify the PCI of the cell), and the terminal device searches for the PCI of the changed cell and performs downlink or uplink synchronization, and thus there is no need to issue a switching command. For the sake of ease of understanding, the switching in which the PCI changes or remains unchanged but does not require the issuance of a switching command as the switching without L3 signaling can be uniformly referred to as switching without L3 signaling.

[0119] However, if Figure 8As shown, it is a schematic diagram of a switching scenario. In this scenario, the current service cell of the terminal device is the cell corresponding to PCI#1, and the satellite covering the cell corresponding to PCI#1 is switched from satellite 1 to satellite 2. When configuring the switching strategy of PCI unchanged switching (also known as switching without L3 signaling) for the terminal device, due to the mobility of the terminal device, the terminal device at the edge of the cell coverage corresponding to PCI#1 may move out of the coverage of the cell corresponding to PCI#1, or because the coverage of satellite 1 and satellite 2 is inconsistent, the coverage of satellite 2 is smaller than the coverage of satellite 1, and the terminal device at the edge of the cell coverage corresponding to PCI#1 may not be within the coverage of satellite 2. Therefore, after adopting the switching strategy of satellite change and PCI unchanged, the terminal device at the edge of the cell coverage corresponding to PCI#1 still needs to switch to the neighboring cell. For the scenario where the terminal device at the edge of the cell coverage still needs to switch to the neighboring cell due to the movement of the terminal device or the inconsistent coverage of the new and old satellites, the network side can configure CHO for the terminal device at the edge of the cell coverage at the same time. For example, when the signal quality of the cell corresponding to PCI#1 deteriorates, the terminal device can switch to the cell corresponding to PCI#2 according to CHO, thereby improving the robustness of the switching.

[0120] However, for the hard handover scenario, there is a coverage gap (GAP) between the new and old satellites of the cell corresponding to PCI#1. Since the terminal device has been disconnected from the current serving cell during the GAP, the terminal device may not be able to evaluate the CHO execution condition. In addition, if both PCI unchanged handover and CHO meet the corresponding execution conditions at the same time, the terminal device is unclear whether to execute CHO or PCI unchanged handover.

[0121] Based on this, an embodiment of the present application proposes a switching method to improve the switching efficiency of a terminal device.

[0122] The method can be applied to the scenario of handover between satellites (or base stations). In the scenario of handover between satellites, take the example of a terminal device switching from a first network device to a second network device. The first network device can be a first satellite, and the second network device can be a second satellite. Figure 1 For the system in, the first satellite and the second satellite may be satellites connected to the base station. The base station connected to the first satellite and the base station connected to the second satellite may be the same base station, that is, the base station connected to the first satellite and the base station connected to the second satellite is the source base station; or the base station connected to the first satellite and the base station connected to the second satellite may be different base stations, that is, the base station connected to the first satellite is the source base station, and the base station connected to the second satellite is the target base station. Figure 2 For the NTN system in the embodiment, the first satellite and the second satellite may be satellites having base station functions, that is, the first satellite is a source base station and the second satellite is a target base station.

[0123] In the inter-base station handover scenario, take the example of a terminal device switching from a first network device to a third network device. The first network device is the source base station, and the third network device is the target base station. Figure 1 For the system in FIG. 1 , the first network device and the third network device may be base stations connected to the satellite. Figure 2 For the NTN system in the embodiment, the first network device and the third network device may be satellites having base station functions.

[0124] For ease of explanation, the following takes the first network device as a source base station or a first satellite connected to the source base station, the second network device as a second satellite connected to the source base station, and the third network device as a target base station as an example.

[0125] like Fig. 9 As shown, a schematic diagram of a switching method provided in an embodiment of the present application is provided. In the following description, the method is performed by a first network device (or a chip applied to the first network device) and a terminal device (or a chip applied to the terminal device) as an example. The method includes:

[0126] S901: The first network device sends CHO configuration information to the terminal device. Correspondingly, the terminal device receives the CHO configuration information from the first network device.

[0127] The first network device may be a network device to which a source cell of the terminal device belongs. For example, the first network device may be a source base station or a first satellite connected to the source base station. Optionally, the terminal device may be at the coverage edge of the source cell.

[0128] The CHO configuration information can be used for the terminal device to access the first target cell when the first condition is met. Specifically, the CHO configuration information may include the first condition (also called the CHO execution condition) and the information of the first target cell. The information of the first target cell includes the configuration information required to access the first target cell, such as the CGI of the first target cell, or the PCI of the first target cell and the frequency information corresponding to the first target cell. Optionally, the first condition may be generated by the first network device, and the information of the first target cell may be generated by the network device corresponding to the first target cell and sent to the first network device.

[0129] In a possible implementation, the first condition may include, but is not limited to, one or more of the following: an execution condition based on time; an execution condition based on distance; or an execution condition based on signal quality. Exemplarily, the first condition may include only an execution condition based on time. Or the first condition may include only an execution condition based on distance. Or the first condition may include only an execution condition based on signal quality. Or the first condition may include an execution condition based on time and an execution condition based on signal quality. Or the first condition may include an execution condition based on distance and an execution condition based on signal quality. Or the first condition may include an execution condition based on distance and an execution condition based on time.

[0130] The time-based execution condition may include a time window. For example, the first network device sets a time window (T1, T2) for the terminal to configure CHO execution (i.e., access to the first target cell). If the current time is within the time window (T1, T2), the terminal device may determine that the time-based execution condition is met, so that the terminal device may execute CHO within the time window (T1, T2).

[0131] The distance-based execution condition may include a distance threshold. For example, the first network device configures the distance threshold D1 and the distance threshold D2 for the terminal device to execute CHO (i.e., access the first target cell). If the distance from the terminal device to the first target cell is less than the distance threshold D1, and the distance from the terminal device to the source cell is greater than the distance threshold D2, the terminal device may determine that the distance-based execution condition is met, so that the terminal device may execute CHO. Optionally, the distance from the terminal device to the cell may be the distance to the cell reference point, and the cell reference point may be understood as a reference point where the relative position between the network devices corresponding to the cell remains unchanged, for example, the position of the cell reference point may be the center position of the cell.

[0132] The execution condition based on signal quality may include one or more of A1 event (event A1), A2 event (event A2), A3 event (event A3), A4 event (event A4), or A5 event (event A5). Exemplarily, the execution condition based on signal quality may include only A1 event. Or the execution condition based on signal quality may include only A2 event. Or the execution condition based on signal quality may include only A3 event. Or the execution condition based on signal quality may include only A4 event. Or the execution condition based on signal quality may include only A5 event. Or the execution condition based on signal quality may include A3 event, A4 event and A5 event. Or the execution condition based on signal quality may include A3 event and A5 event. Or the execution condition based on signal quality may include A4 event and A5 event. Or the execution condition based on signal quality may include A3 event and A4 event. When the execution condition based on signal quality includes the above-mentioned events, if the terminal device determines that the events are satisfied, the terminal device may determine that the execution condition based on signal quality is satisfied.

[0133] Among them, the A1 event means that the signal quality of the source cell is higher than the first absolute threshold, the A2 event means that the signal quality of the source cell is lower than the second absolute threshold, and the A3 event means that the signal quality of the first target cell is higher than the signal quality of the source cell by a bias value. The A4 event means that the signal quality of the first target cell is higher than the third absolute threshold. The A5 event means that the signal quality of the source cell is lower than the fourth absolute threshold and the signal quality of the first target cell is higher than the fifth absolute threshold. Among them, the signal quality of the first target cell or the source cell can be the reference signal received power (reference signal received power, RSRP) of the first target cell or the source cell, the reference signal received quality (reference signal received quality, RSRQ) of the first target cell or the source cell, or a value determined based on the RSRP of the first target cell or the source cell and the RSRQ of the first target cell or the source cell. Optionally, the execution conditions based on signal quality may also include other events, which are not specifically limited in this application.

[0134] Optionally, before the first network device sends the CHO configuration information to the terminal device, the first network device and the terminal device may further perform the following steps:

[0135] Step A1: The first network device sends measurement configuration information to the terminal device, and correspondingly, the terminal device receives the measurement configuration information from the first network device. The measurement configuration information may include one or more of the following: measurement object; report configuration; measurement identity document (ID); measurement quantity configuration; or measurement GAP configuration.

[0136] Step A2: The terminal device sends a measurement report to the first network device, and correspondingly, the first network device receives the measurement report from the terminal device.

[0137] Step A3: The network device selects at least one candidate cell (e.g., a first target cell) for the UE based on the measurement report, and sends a CHO request message to a network device (e.g., a third network device) to which the at least one candidate cell belongs. The first target cell may be one of the at least one candidate cell, and the third network device may be a network device to which the first target cell belongs. For example, the third network device may be a target base station.

[0138] Step A4: The third network device sends a CHO request response message to the first network device, wherein the CHO request response message may include information of the first target cell.

[0139] Optionally, the first network device and the terminal device may further perform the following steps: the first network device sends PCI unchanged switching indication information to the terminal device, and correspondingly, the terminal device receives PCI unchanged switching indication information from the first network device.

[0140] Among them, the PCI unchanged switching indication information can be carried in the system message. The PCI unchanged switching indication information is used to indicate that the terminal device switches to or accesses the second network device when the second condition is met. The second network device can be a network device to which the source cell belongs. For example, the first network device can be a second satellite connected to the source base station. The second condition may include one or more of the following: the time when the first network device stops covering the area where the terminal device is located; the time when the PCI unchanged switching takes effect; the time when the second network device performs downlink synchronization with the terminal device; or the time when the second network device starts to cover the area where the terminal device is located. The time when the first network device stops covering the area where the terminal device is located refers to the service stop time of the first network device (for example, t-service-), wherein the first network device stops service means that the first network device stops or interrupts the service of the terminal device in the corresponding cell, or the first network device stops service means that the first network device stops covering the location of the terminal device or the cell where the terminal device is located; or the time when the first network device stops covering the area where the terminal device is located refers to the time when the source cell stops providing services for the currently served area.

[0141] Specifically, the PCI unchanged switching indication information can be a Boolean value, that is, true or false is used to indicate that the terminal device performs the PCI unchanged switching. Or the PCI unchanged switching indication information can also be the information of the cell, such as the PCI of the cell, etc., and the terminal device is implicitly instructed to perform the PCI unchanged switching and switch to the cell corresponding to the PCI carried in the system message through the cell information. Or the PCI unchanged switching indication information can also be the time parameter t-service, and the terminal device is implicitly instructed to perform the PCI unchanged switching through the time parameter t-service, wherein the time parameter t-service can be the time when the first network device stops covering the area where the terminal device is located, that is, the time when the first network device stops service (for example, t-service1). Alternatively, the PCI unchanged switching indication information can also be the time parameter t-start, and the terminal device is implicitly instructed to perform the PCI unchanged switching through the time parameter t-start, wherein the time parameter t-start can be the time when the second network device starts to cover the area where the terminal device is located (or also called the time when the second network device starts to provide services for the area covered by the source cell), or it can be the time when the PCI unchanged switching takes effect, or it can be the time when the second network device and the terminal device perform downlink synchronization.

[0142] S902: The terminal device determines whether a first condition is met in a first time unit.

[0143] The first time unit is any time unit in a communication gap existing during the switching of the network equipment to which the source cell belongs.

[0144] Exemplarily, the network device to which the source cell belongs can be switched from the first network device to the second network device, the first network device can be the first satellite connected to the source base station, and the second network device can be the second satellite connected to the source base station, that is, the satellite of the source cell can be switched from the first satellite to the second satellite. If the first satellite and the second satellite provide services for the source cell, and there is no overlap in the service time between the first satellite and the second satellite, there will be a communication gap during the satellite switching of the source cell (for example, there is a gap between t-service and t-start). At this time, since the base station of the source cell remains unchanged before and after the satellite switching of the source cell, the terminal device can still be in the RRC connection state (RRC_CONNECTED) in the communication gap. After the terminal device receives the CHO configuration information from the first network device, it can determine whether the first condition is met in any time unit in the communication gap.

[0145] Since the terminal device has been disconnected from the source cell or the first satellite during the communication gap, the terminal device cannot obtain the signal quality of the source cell, resulting in that when the first condition includes an A3 event or an A5 event, the terminal device cannot evaluate the first condition in the communication gap. Therefore, the terminal device may use the signal quality of the source cell obtained before being disconnected from the source cell or the first satellite or the default value to evaluate the A3 event or the A5 event.

[0146] Specifically, the terminal device may determine whether the A3 event or the A5 event is satisfied based on the first signal quality of the source cell. It can be understood that the terminal device determines that the signal quality of the source cell is the first signal quality.

[0147] Among them, the first signal quality is the signal quality of the source cell obtained by the terminal device before the time when the first network device stops covering the area where the terminal device is located, or when the time when the first network device stops covering the area where the terminal device is located. The time when the first network device stops covering the area where the terminal device is located refers to the expiration or arrival of the service stop time (for example, t-service1) of the first network device. The first network device stops service means that the first network device stops or interrupts the service of the terminal device in the corresponding cell, or the first network device stops service means that the first network device stops covering the location of the terminal device or the cell where the terminal device is located.

[0148] Alternatively, the terminal device may determine whether the A3 event or the A5 event is satisfied based on the second signal quality of the source cell. The second signal quality is a default value. For example, the second signal quality may be -100 decibel milliwatts (dBm). The default value may be configured by the network device or may be agreed upon by the protocol, and the embodiments of the present application do not specifically limit this.

[0149] Alternatively, when the first condition includes one of the A3 event or the A5 event, and includes at least one of the time-based execution condition, the distance-based execution condition, and the A4 event, the terminal device may only determine whether at least one of the time-based execution condition, the distance-based execution condition, and the A4 event in the first condition is satisfied (it can be understood that the terminal device can ignore the A3 event or the A5 event). If at least one of the time-based execution condition, the distance-based execution condition, and the A4 event in the first condition is satisfied, the terminal device may consider that the first condition is satisfied; otherwise, the first condition is considered not to be satisfied.

[0150] Alternatively, when the first condition includes one of the A3 event or the A5 event, the terminal device may determine whether to access the first target cell based on whether the signal quality of the first target cell exceeds threshold #1, wherein the threshold #1 may be a default value or may be sent to the terminal device by the first network device. If the signal quality of the first target cell exceeds threshold #1, the execution condition of the first target cell is met or the terminal device accesses the first target cell; otherwise, the execution condition of the first target cell is not met or the terminal device does not access the first target cell. Furthermore, if the first condition also includes a time-based execution condition and / or a distance-based execution condition, the terminal device considers that the execution condition of the first target cell is met or the terminal device accesses the first target cell only when the time-based execution condition and / or the distance-based execution condition are met.

[0151] Alternatively, when the first condition includes one of the A3 event or the A5 event, the terminal device can determine whether to access the first target cell based on whether the terminal device has uplink or downlink data to be transmitted. If the terminal device has uplink or downlink data to be transmitted (or the amount of uplink or downlink data to be transmitted exceeds threshold #2), the execution condition of the first target cell is met or the terminal device accesses the first target cell, otherwise the execution condition of the first target cell is not met or the terminal device does not access the first target cell. Furthermore, if the first condition also includes a time-based execution condition and / or a distance-based execution condition, the terminal device considers that the execution condition of the first target cell is met or the terminal device accesses the first target cell only when the time-based execution condition and / or the distance-based execution condition are met.

[0152] In a possible implementation, the terminal device may determine whether the first condition is satisfied in the first time unit based on the communication gap existing during the switching of the network device to which the source cell belongs. Specifically, the terminal device may determine whether the communication gap existing during the switching of the network device to which the source cell belongs is greater than the first threshold value. If the communication gap is greater than the first threshold value, the terminal device may determine that the first condition is satisfied in the first time unit; otherwise, it is determined that the first condition is not satisfied in the first time unit. The first threshold value may be configured by the network device, may be agreed upon by the protocol, or may be determined by the terminal device, and the embodiments of the present application do not specifically limit this.

[0153] In a possible implementation, the terminal device may determine whether the first condition is satisfied in the first time unit based on the communication gap existing during the switching of the network device to which the source cell belongs. Specifically, the terminal device may determine whether the first condition is satisfied in the first time unit by using the rule of the terminal device determining whether the A3 event or the A5 event is satisfied based on the first signal quality of the source cell when the communication gap existing during the switching of the network device to which the source cell belongs is greater than the first threshold.

[0154] In a possible implementation, after receiving the CHO configuration information from the first network device, the terminal device may not determine whether the first condition is met in the first time unit. At this time, if the terminal device has received the PCI unchanged switching indication information from the first network device, the terminal device can maintain the configuration of the source cell and access the second network device when the second network device begins to cover the location or cell where the terminal device is located, that is, the terminal device can perform PCI unchanged switching.

[0155] When the terminal device does not determine whether the first condition is met in the first time unit, the first network device and the terminal device can retain the CHO configuration in the communication gap. The terminal device can determine whether the first condition is met in the second time unit. Optionally, the terminal device can access the first target cell if the first condition is met. The second time unit is any time unit after the communication gap that exists during the switching of the network device to which the source cell belongs.

[0156] Alternatively, the first network device and the terminal device may retain the CHO configuration in the communication gap. If the terminal device has received the PCI unchanged switching indication information from the first network device, the terminal device may access the first target cell based on the information of the first target cell in the CHO configuration information when performing RRC re-establishment due to the failure of the PCI unchanged switching.

[0157] Alternatively, the first network device and the terminal device may not retain the CHO configuration in the communication gap. The first network device may instruct the third network device to release the resources reserved by the first target cell for the terminal device in the communication gap. Alternatively, if the first condition includes a time window (T1, T2), the third network device may release the resources reserved by the first target cell for the terminal device after T2.

[0158] S903: When the first condition is met, the terminal device accesses the first target cell.

[0159] Specifically, the terminal device accesses the first target cell when the first condition is met, that is, the source cell is switched to the first target cell. Optionally, after the switching is completed, the third network device can send a switching success message to the first network device, and the first network device instructs the network devices to which other candidate cells except the first target cell belong to release the resources reserved by other candidate cells for the terminal device. If the first condition includes a time window (T1, T2), the network devices to which other candidate cells belong can release the resources reserved by other candidate cells for the terminal device after T2.

[0160] In a possible implementation, if the terminal device also satisfies the first condition corresponding to other candidate cells except the first target cell, the terminal device can select from the first target cell and the other candidate cells to access a cell configured with dedicated random access resources for the terminal device. For example, if the first target cell configures contention free random access (CFRA) resources for the terminal device, or configures the terminal device to access the first target cell through rach-less, the terminal device can select from the first target cell and the other candidate cells to access the first target cell. Optionally, the other candidate cells do not have CFRA resources configured for the terminal device, or do not configure the terminal device to access the first target cell through rach-less. Alternatively, the terminal device can also select from the first target cell and the other candidate cells to access the cell with the latest service stop time of the network device to which it belongs. For example, if the service stop time of the third network device (e.g., t-service3) is the latest, the terminal device can select from the first target cell and the other candidate cells to access the first target cell.

[0161] In a possible implementation, the terminal device may also access the second target cell when the first condition is not met. The second target cell configures dedicated random access resources for the terminal device. For example, the second target cell configures CFRA resources for the terminal device, or configures the terminal device to access the second target cell through rach-less.

[0162] In a possible implementation, the first terminal device accesses the second network device when the first condition is not met but the second condition is met. Exemplarily, the current terminal device uses the configuration of the cell corresponding to PCI#1 to access the cell corresponding to PCI#1, that is, the source cell is the cell corresponding to PCI#1, and the first satellite provides services for the source cell. As the satellite moves, the satellite covering the cell corresponding to PCI#1 switches from the first satellite to the second satellite. If the terminal device has configured a switching strategy for switching without changing the PCI, the terminal device can maintain the configuration of the cell corresponding to PCI#1 at this time, and access the second satellite after the coverage of the second satellite arrives, and the second satellite provides services for the source cell at this time.

[0163] In a possible implementation, the terminal device accesses the first target cell or accesses the second network device when the first condition and the second condition are met.

[0164] Specifically, the terminal device can access the first target cell if the first condition, the second condition, and the third condition are met. Optionally, the first condition may be an execution condition that includes an A4 or A5 event, or may be an execution condition that does not include an A4 or A5 event. The third condition includes one or more of the following:

[0165] The time when the third network device (or also known as the CHO target network device) stops covering the area where the terminal device is located is later than the time when the second network device (or also known as the PCI unchanged switching target network device) stops covering the area where the terminal device is located. The time when the third network device stops covering the area where the terminal device is located refers to the service stop time of the third network device (for example, t-service3) (or also known as the time when the first target cell provides services to the coverage area of ​​the first target cell through the third network device), and the third network device stops service when the third network device stops or interrupts the service of the terminal device in the corresponding cell, or refers to the third network device stops covering the location of the terminal device or the cell where the terminal device is located. The time when the second network device stops covering the area where the terminal device is located refers to the service stop time of the second network device (for example, t-service2) (or also known as the time when the source cell provides services to the coverage area of ​​the source cell through the second network device), and the second network device stops service when the second network device stops or interrupts the service of the terminal device in the corresponding cell, or refers to the first network device stops covering the location of the terminal device or the cell where the terminal device is located. That is, t-service3 is later than t-service2;

[0166] The first target cell configures a dedicated random access resource for the terminal device, for example, the first target cell configures a CFRA resource or a rach-less resource for the terminal device, or the source cell does not configure a CFRA resource or a rach-less resource for the terminal device; or,

[0167] The distance between the first target cell reference point and the terminal device (for example, D1) is smaller than the distance between the source cell reference point and the terminal device (for example, D2), that is, D1 is smaller than D2.

[0168] Alternatively, the terminal device may access the second network device if the first condition, the second condition, and the fourth condition are met. The fourth condition includes one or more of the following:

[0169] The time when the second network device stops covering the area where the terminal device is located is later than the time when the third network device stops covering the area where the terminal device is located. That is, t-service3 is later than t-service2;

[0170] The source cell configures dedicated random access resources for the terminal device, for example, the source cell configures CFRA resources or rach-less resources for the terminal device, or the first target cell does not configure CFRA resources or rach-less resources for the terminal device; or,

[0171] The distance between the source cell reference point and the terminal device (for example, D2) is smaller than the distance between the first target cell reference point and the terminal device (for example, D1), that is, D2 is smaller than D1.

[0172] The above scheme clarifies that when there is a communication gap during the switching of the network device to which the source cell belongs, the terminal device can evaluate the CHO execution condition (i.e., the first condition) in the communication gap. For example, when the satellite of the source cell is switched from the first satellite to the second satellite, and the first satellite and the second satellite do not overlap in service time when providing services to the source cell, there will be a communication gap during the switching of the first satellite and the second satellite, and the terminal device can evaluate the CHO execution condition in the communication gap. Since the terminal device may move out of the coverage of the source cell or the coverage of the first satellite and the second satellite may be inconsistent after the switching of the first satellite and the second satellite, the terminal device needs to execute CHO (i.e., access the first target cell). By evaluating the CHO execution condition in advance in the communication gap, the switching efficiency of the terminal device can be improved. And it is clear that when the terminal device is configured with CHO and PCI unchanged switching, the terminal device can choose to execute CHO (i.e., access the first target cell) or PCI unchanged switching (i.e., access the second network device) when both the CHO execution condition (i.e., the first condition) and the PCI unchanged switching execution condition (i.e., the second condition) are met, clarifying the switching strategy of the terminal device and improving the switching efficiency of the terminal device.

[0173] In the embodiment of the present application, the first network device or the terminal device can perform some or all of the steps in the embodiment of the present application, and these steps or operations are only examples. The embodiment of the present application can also perform other operations or variations of various operations. In addition, each step can be performed in a different order presented in the embodiment of the present application, and it is possible not to perform all the operations in the embodiment of the present application.

[0174] In order to implement the functions in the above-mentioned embodiments, the first network device or the terminal device includes a hardware structure and / or software module corresponding to each function. It should be easily appreciated by those skilled in the art that, in combination with the units and method steps of each example described in the embodiments disclosed in this application, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0175] Fig.10 and Fig.11 A schematic diagram of the structure of possible communication devices provided for embodiments of the present application. These communication devices can be used to implement the functions of the first network device or terminal device in the above method embodiments, and thus can also achieve the beneficial effects possessed by the above method embodiments. In an embodiment of the present application, the communication device can be the first network device or terminal device, and can also be a module (such as a chip) applied to the first network device or terminal device.

[0176] Fig.10 The communication device 1000 shown includes a processing unit 1010 and a communication unit 1020. The communication device 1000 is used to implement the function of the first network device or the terminal device in the above method embodiment.

[0177] When the communication device 1000 is used to implement the functions of the terminal device in the above embodiment:

[0178] A communication unit, configured to receive conditional handover CHO configuration information from a first network device, where the first network device is a network device to which a source cell of the terminal device belongs, and the CHO configuration information is used for the terminal device to access a first target cell when a first condition is met;

[0179] A processing unit, configured to determine whether the first condition is met in a first time unit, where the first time unit is any time unit in a communication gap existing during a switching period of a network device to which the source cell belongs;

[0180] The processing unit is configured to access the first target cell if the first condition is met.

[0181] When the communication device 1000 is used to implement the function of the first network device in the above embodiment:

[0182] A communication unit, used to send CHO configuration information to a terminal device, wherein the CHO configuration information is used for the terminal device to access a first target cell when a first condition is met, wherein the first condition includes one or more of the following: an execution condition based on time; an execution condition based on distance; or an execution condition based on signal quality.

[0183] When the communication device 1000 is used to implement the functions of the terminal device in the above embodiment:

[0184] a communication unit, configured to receive CHO configuration information and PCI unchanged switching indication information from a first network device, the first network device being a network device to which a source cell of the terminal device belongs, the CHO configuration information being used for the terminal device to access a first target cell when a first condition is met, and the PCI unchanged switching indication information being used to instruct the terminal device to access a second network device when a second condition is met;

[0185] A processing unit is used to access the first target cell or access the second network device when the first condition and the second condition are met.

[0186] When the communication device 1000 is used to implement the function of the first network device in the above embodiment:

[0187] A communication unit, used to send CHO configuration information and PCI unchanged switching indication information to a terminal device, wherein the CHO configuration information is used for the terminal device to access a first target cell when a first condition is met, and the PCI unchanged switching indication information is used to instruct the terminal device to access a second network device when a second condition is met, wherein the first condition includes one or more of the following: an execution condition based on time; an execution condition based on distance; or an execution condition based on signal quality.

[0188] For a more detailed description of the processing unit 1010 and the communication unit 1020, reference may be made to the relevant description in the above method embodiment, which will not be repeated here.

[0189] Fig.11 The communication device 1100 shown includes a processor 1110 and an interface circuit 1120. The processor 1110 and the interface circuit 1120 are coupled to each other. The interface circuit 1120 may be a transceiver or an input / output interface. Exemplarily, the communication device 1100 may also include a memory 1130 for storing instructions executed by the processor 1110 or storing input data required by the processor 1110 to execute instructions or storing data generated after the processor 1110 executes instructions.

[0190] When the communication device 1100 is used to implement the above method embodiment, the processor 1110 is used to implement the function of the above processing unit 1010 , and the interface circuit 1120 is used to implement the function of the above communication unit 1020 .

[0191] When the above communication device is a chip applied to a terminal device, the chip of the terminal device implements the functions of the terminal device in the above method embodiment. The chip of the terminal device receives information from other modules (such as a radio frequency module or an antenna) in the terminal device, and the information is sent to the terminal device by the first network device; or the chip of the terminal device sends information to other modules (such as a radio frequency module or an antenna) in the terminal device, and the information is sent to the first network device by the terminal device.

[0192] When the above-mentioned communication device is a module applied to the first network device, the module of the first network device implements the function of the first network device in the above-mentioned method embodiment. The module of the first network device receives information from other modules in the first network device (such as a radio frequency module or an antenna), and the information is sent by the terminal device to the first network device; or, the module of the first network device sends information to other modules in the first network device (such as a radio frequency module or an antenna), and the information is sent by the first network device to the terminal device. The module of the first network device here can be a chip of the first network device, or it can be a DU or other module, and the DU here can be a DU under the open radio access network (O-RAN) architecture.

[0193] The processor in the embodiments of the present application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0194] The method steps in the embodiments of the present application can be implemented by hardware, or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in a random access memory, a flash memory, a read-only memory, a programmable read-only memory, an erasable programmable read-only memory, an electrically erasable programmable read-only memory, a register, a hard disk, a mobile hard disk, a compact disc read-only memory (compact disc read-only memory, CD-ROM) or any other form of storage medium well known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and can write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC. In addition, the ASIC can be located in a first network device or a terminal device. Of course, the processor and the storage medium can also be present in the first network device or the terminal device as discrete components.

[0195] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0196] Those of ordinary skill in the art will appreciate that the various illustrative logical blocks and steps described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or in a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel may 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.

[0197] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0198] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0199] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0200] If the functions are implemented in the form of 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 part of the technical solution of the present application that contributes essentially or the part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM), RAM, magnetic disks or optical disks.

[0201] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A switching method, characterized in that: The method is performed by a terminal device or a chip applied to the terminal device, and includes: receiving conditional handover CHO configuration information from a first network device, where the first network device is a network device to which a source cell of the terminal device belongs, and the CHO configuration information is used for the terminal device to access a first target cell when a first condition is met; Determine whether the first condition is met in a first time unit, where the first time unit is any time unit in a communication gap existing during a switching period of a network device to which the source cell belongs; When the first condition is met, access the first target cell.

2. The method according to claim 1, characterized in that The first condition includes one or more of the following: Time-based execution conditions; Enforcement conditions based on distance; or Execution conditions based on signal quality.

3. The method according to claim 2, characterized in that The time-based execution condition includes a time window.

4. The method according to claim 2, characterized in that The distance-based execution condition includes a distance threshold.

5. The method according to claim 2, characterized in that The execution condition based on signal quality includes one or more of an A3 event, an A4 event, or an A5 event.

6. The method according to claim 5, characterized in that The method further comprises: determining whether the A3 event or the A5 event is satisfied based on a first signal quality of the source cell, wherein the first signal quality is a signal quality of the source cell before the time when the first network device stops covering the area where the terminal device is located, or when the time when the first network device stops covering the area where the terminal device is located; or Whether the A3 event or the A5 event is satisfied is determined based on a second signal quality of the source cell, where the second signal quality is a default value.

7. The method according to any one of claims 1 to 6, characterized in that: The method further comprises: When the first condition is not met, access is made to a second target cell, and the second target cell configures dedicated random access resources for the terminal device.

8. The method according to any one of claims 1 to 6, characterized in that: The method further comprises: Receiving physical cell identifier PCI unchanged switching indication information from the first network device, where the PCI unchanged switching indication information is used to instruct the terminal device to access the second network device if a second condition is met; When the first condition is not met but the second condition is met, access the second network device.

9. The method according to claim 8, characterized in that The second condition includes one or more of the following: The time when the first network device stops covering the area where the terminal device is located is reached; The time when the PCI unchanged switch takes effect; The time for the second network device to perform downlink synchronization with the terminal device; or The time when the second network device starts to cover the area where the terminal device is located.

10. The method according to any one of claims 1 to 9, characterized in that: The method further comprises: In a case where the communication gap is greater than a first threshold, it is determined whether the first condition is satisfied in the first time unit.

11. A switching method, characterized in that: The method is performed by a first network device or a chip applied to the first network device, and includes: Send CHO configuration information to a terminal device, where the CHO configuration information is used for the terminal device to access a first target cell when a first condition is met, where the first condition includes one or more of the following: Time-based execution conditions; Enforcement conditions based on distance; or Execution conditions based on signal quality.

12. The method according to claim 11, characterized in that The time-based execution condition includes a time window.

13. The method according to claim 11, characterized in that The distance-based execution condition includes a distance threshold.

14. The method according to claim 11, characterized in that The execution condition based on signal quality includes one or more of an A3 event, an A4 event, or an A5 event.

15. The method according to claim 14, characterized in that The method further comprises: Determine whether the A3 event or the A5 event is satisfied based on a first signal quality of a source cell of the terminal device, wherein the first signal quality is a signal quality of the source cell before the time when the first network device stops covering the area where the terminal device is located, or when the first network device stops covering the area where the terminal device is located; or Whether the A3 event or the A5 event is satisfied is determined based on a second signal quality of a source cell of the terminal device, where the second signal quality is a default value.

16. A communication device, characterized in that: The method comprises a module for executing the method as claimed in any one of claims 1 to 10, or a module for executing the method as claimed in any one of claims 10 to 15.

17. A communication device, characterized in that: It includes a processor and an interface circuit, wherein the interface circuit is used to receive signals from other communication devices outside the communication device and transmit them to the processor or send signals from the processor to other communication devices outside the communication device, and the processor implements the method as described in any one of claims 1 to 10 or the method as described in any one of claims 10 to 15 through a logic circuit or by executing code instructions.

18. A communication device, characterized in that: include: Memory for storing computer programs; A processor, configured to call and run the computer program from the memory to implement the method according to any one of claims 1 to 10, or to implement the method according to any one of claims 10 to 15.

19. A chip system, characterized in that: include: Memory for storing computer programs; A processor, configured to call and run the computer program from the memory, so that a device equipped with the chip system executes the method as claimed in any one of claims 1 to 10, or executes the method as claimed in any one of claims 10 to 15.

20. A computer program product, characterized in that The invention comprises a computer program, which, when executed by a communication device, implements the method according to any one of claims 1 to 15.

21. A computer-readable storage medium, characterized in that: The storage medium stores a computer program or an instruction. When the computer program or the instruction is executed by the communication device, the method according to any one of claims 1 to 15 is implemented.

22. A communication system, characterized in that: include: A terminal device, configured to execute the method according to any one of claims 1 to 10; The first network device is configured to execute the method according to any one of claims 10 to 15.

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