Communication method and communication apparatus

Abstract

The present application provides a communication method and a communication apparatus. The method comprises: a terminal device receives instruction information of a first network device, wherein the terminal device is a terminal device for access by means of a first cell of the first network device, and the instruction information is used for instructing the terminal device to measure a reference signal sent from a second network device by means of the first cell; the terminal device receives the reference signal sent from the second network device by means of the first cell; and the terminal device measures the signal quality of the reference signal on the basis of the instruction information, and sends the signal quality of the reference signal to the first network device. The solution can reduce the probability of radio link failure in terminal devices caused by execution of handover.

Description

Communication method and communication device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on January 18, 2024, with application number 202410078713.3 and application name “Communication Method and Communication Device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communication technology, and in particular to a communication method and a communication device. Background Art

[0003] Non-terrestrial networks (NTNs) enable communications using non-terrestrial network equipment. These include aerial network equipment such as satellites, drones, and high-altitude platform station (HAPS) communication systems. NTNs offer advantages such as wide coverage, long communication distances, high reliability, flexibility, and high throughput. Unaffected by geographical conditions, climate conditions, and natural disasters, NTNs have been widely used in aviation, maritime, and military communications. Introducing NTNs into fifth-generation (5G) mobile networks and subsequent evolutionary system architectures, such as sixth-generation (6G) systems, will significantly improve user experience. NTNs can enhance communication reliability, providing more stable communication services for users in high-speed scenarios like trains and airplanes. They can also extend coverage, such as providing communication services for users in the ocean or desert. Furthermore, NTNs offer more data transmission resources and support a greater number of connections. Therefore, the importance of NTNs is expected to continue to grow in the future. When NTN is introduced into the 5G mobile network and the subsequent evolution of the system architecture, the switching technology of terminal devices needs further research. Summary of the Invention

[0004] Embodiments of the present application provide a communication method and a communication device for reducing the probability of wireless link failure caused by switching of a terminal device.

[0005] In a first aspect, an embodiment of the present application provides a communication method, which can be executed by a terminal device or a module (such as a chip) in the terminal device, wherein the terminal device is a terminal device accessed through a first cell of the first network device. The method includes: receiving instruction information from the first network device, the instruction information is used to instruct the terminal device to measure a reference signal sent from a second network device through the first cell, and receiving a reference signal from the first cell of the second network device. After receiving the reference signal, the signal quality of the reference signal is measured and the signal quality of the reference signal is sent to the first network device. In this solution, the terminal device accesses the first cell through the first network device, measures the quality of the reference signal sent from the second network device through the first cell according to the instruction information of the first network device, and sends the reference signal quality to the network device, thereby avoiding the handover failure or the reduction of link quality after the handover due to the lack of knowledge of the signal quality of the second network device, and reducing the probability of wireless link failure of the terminal device due to the handover. Further, according to the above solution, after the network device receives the reference signal, the handover strategy of the terminal device can be determined according to the quality of the reference signal. For example, if the network device determines that the quality of the reference signal is poor, it can instruct the terminal device not to continue switching to access the first cell through the second network device, or it can instruct the terminal device to switch to other cells with good signals, such as a neighboring cell of the first cell.

[0006] In one possible implementation method, a terminal device receives a first time and a second time from the first network device, where the first time indicates the time when the first network device stops providing service for the first cell, and the second time indicates the time when the second network device starts providing service for the first cell, wherein the second time is less than or equal to the first time. The terminal device measures the signal quality of a reference signal between the second time and the first time. In this solution, the terminal device can determine when to measure the reference signal of the first cell of the second network device based on the received first and second time.

[0007] In one possible implementation method, receiving the indication information from the first network device includes: the terminal device receiving measurement configuration information from the first network device, the measurement configuration information including the indication information, the measurement configuration information being used to configure the terminal device to measure the reference signal. In this solution, the terminal device can obtain the indication information by receiving the measurement configuration information without requiring additional signaling to receive the indication information, thereby reducing system signaling overhead and terminal device processing complexity.

[0008] In one possible implementation method, the measurement configuration information further includes a measurement object and report configuration information, wherein the measurement object is a measurement object corresponding to the first cell. In this solution, the terminal device can clearly specify that it wants to perform measurements according to the measurement object corresponding to the first cell.

[0009] In one possible implementation method, the terminal device measures the signal quality of the reference signal based on the indication information, including: the terminal device receives first SMTC information and second SMTC information from a first network device, the terminal device measures the reference signal of the first cell of the second network device and the reference signal of the neighboring cell of the first cell based on the first SMTC information, and the terminal device measures the reference signal of the neighboring cell of the first cell based on the second SMTC information.

[0010] In one possible implementation method, the terminal device measures the reference signal of the first cell of the second network device and the reference signal of the neighboring cell of the first cell based on the first SMTC information, including: the terminal device measures the reference signal of the first cell of the second network device and the reference signal of the neighboring cell of the first cell based on the first SMTC information between the second moment and the first moment.

[0011] In a possible implementation method, the terminal device measures the reference signal of the neighboring cell of the first cell based on the second SMTC information, including: the terminal device measures the reference signal of the neighboring cell of the first cell based on the second SMTC information before the second moment or after the first moment.

[0012] In one possible implementation method, the signal quality of the reference signal is measured between the second moment and the first moment, including: the terminal device measures the signal quality of the first cell from the second network device between the second moment and the first moment, and measures the signal quality of the first cell from the first network device between the second moment and the first moment.

[0013] In a possible implementation method, the terminal device maintains the measured signal quality of the first cell of the second network device and the measured signal quality of the first cell of the first network device between the second moment and the first moment.

[0014] In one possible implementation method, the terminal device receives first condition information from the first network device, the first condition information including wireless resource configuration information of the first candidate cell and the execution conditions for switching to the first candidate cell; the terminal device receives second condition information from the first network device, the second condition information is used to indicate that when the measured signal quality of the first cell reference signal of the second network device is lower than the first threshold, conditional switching of the first candidate cell is performed.

[0015] In a possible implementation method, the terminal device switches from accessing the first cell through the first network device to accessing the first cell through the second network device at a third moment, and the third moment is between the second moment and the first moment.

[0016] In the second aspect, an embodiment of the present application provides a communication method, which can be executed by a first network device or a module (such as a chip) in the first network device. The method includes: the network device sends an indication message to the terminal device, the indication message is used to instruct the terminal device to measure the reference signal of the first cell from the second network device, the first cell being the cell accessed by the terminal device through the first network device; the network device also receives the signal quality of the reference signal from the terminal device. Therefore, the first network device can evaluate whether to switch the terminal device to the second network device based on the signal quality. If the reference signal quality of the first cell from the second network device is poor, the terminal device can avoid continuing to switch to access the first cell through the second network device. For example, the terminal device can switch to other cells with good signal quality, thereby reducing the probability of wireless link failure caused by the terminal device performing the switch.

[0017] In one possible implementation method, the first network device sends a first moment and a second moment to the terminal device, where the first moment indicates the moment when the first network device stops providing services for the first cell, and the second moment indicates the moment when the second network device starts providing services for the first cell, wherein the second moment is less than or equal to the first moment.

[0018] In a possible implementation method, the first network device sends indication information to the terminal device, including: the first network device sends measurement configuration information to the terminal device, the measurement configuration information includes the indication information, the measurement configuration information is used to configure the terminal device to measure a reference signal, the measurement configuration information includes a measurement object and report configuration information, wherein the measurement object is a measurement object corresponding to the first cell.

[0019] In one possible implementation method, the first network device sends first SMTC information and second SMTC information to the terminal device, wherein the first SMTC information is used to measure the reference signal of the first cell of the second network device and the reference signal of the neighboring cell of the first cell, and the second SMTC configuration information is used to measure the reference signal of the neighboring cell of the first cell.

[0020] In one possible implementation method, the first network device sends first condition information to the terminal device, where the first condition information includes wireless resource configuration information of the first candidate cell and the execution conditions for switching to the first candidate cell; the first network device sends second condition information to the terminal device, where the second condition information is used to indicate that when the measured signal quality of the reference signal of the first cell of the second network device is lower than the first threshold, conditional switching of the first candidate cell is performed.

[0021] Regarding the beneficial effects of various implementation methods of the first network device, reference can be made to the beneficial effects of various implementation methods of the terminal device of the first aspect, and no further details will be given.

[0022] On the third aspect, an embodiment of the present application provides a communication method, which can be executed by a terminal device or a module (such as a chip) in the terminal device. The method includes: the terminal device receives a first moment and a second moment from a first network device, the first moment indicating the moment when the first network device stops providing services for the first cell, and the second moment indicating the moment when the second network device starts providing services for the first cell, wherein the second moment is less than or equal to the first moment; the terminal device receives the second indication information; the terminal device determines, based on the second indication information, not to access the first cell through the second network device between the second moment and the first moment. In this scheme, it can be ensured that the terminal devices in the first cell between the second moment and the first moment all access the first cell through the first network device, thereby avoiding the situation where some terminal devices access the first cell through the first network device and some terminal devices access the first cell through the second network device, resulting in interference between terminal devices in the same cell.

[0023] In one possible implementation method, the terminal device receives the second indication information through the first network device; or, receives the second indication information through the second network device.

[0024] In one possible implementation method, the second indication information is used to instruct the terminal device not to access the first cell through the second network device between the second moment and the first moment.

[0025] In a possible implementation method, the second indication information is used to indicate that the second network device is the target network device of the first cell.

[0026] In a fourth aspect, an embodiment of the present application provides a communication method, which can be performed by a first network device or a module (such as a chip) in the first network device. The method includes: the first network device sends a first moment and a second moment to a terminal device, the first moment indicating the moment when the first network device stops providing services for a first cell, and the second moment indicating the moment when the second network device starts providing services for the first cell, wherein the second moment is less than or equal to the first moment; the first network device sends second indication information to the terminal device, the second indication information being used to determine that the terminal device does not access the first cell through the second network device between the second moment and the first moment.

[0027] In a possible implementation method, the second indication information is used to indicate that the second network device is the target network device of the first cell.

[0028] Regarding the beneficial effects of various implementation methods of the first network device, you can refer to the beneficial effects of various implementation methods of the terminal device in the third aspect, and will not repeat them here.

[0029] In a fifth aspect, an embodiment of the present application provides a communication device, which can be a terminal device or a module (such as a chip) in the terminal device. The device has the function of implementing any implementation method of the first aspect above. The function can 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.

[0030] In a sixth aspect, an embodiment of the present application provides a communication device, which may be a first network device or a module (such as a chip) in the first network device. The device has the function of implementing any implementation method of the second aspect described 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.

[0031] 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 above-mentioned first to fourth aspects.

[0032] In an eighth aspect, an embodiment of the present application provides a communication device, comprising a processor and an interface circuit, wherein the processor is configured to communicate with other devices via the interface circuit and execute any of the implementation methods described in the first to fourth aspects. The processor comprises one or more.

[0033] In a ninth aspect, an embodiment of the present application provides a communication device, comprising a processor coupled to a memory, the processor configured to call a program stored in the memory to execute any of the implementation methods described in aspects 1 to 4 above. The memory may be located within or outside the device, and the processor may be one or more.

[0034] In the tenth aspect, an embodiment of the present application provides a communication device, comprising a memory; the memory is used to store computer instructions, and when the computer instructions are executed, the device executes any implementation method in the above-mentioned first to fourth aspects.

[0035] In a possible implementation method, the communication device further includes a processor configured to execute computer instructions stored in the memory.

[0036] 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 run by a communication device, any implementation method in the above-mentioned first to fourth aspects is executed.

[0037] In the twelfth aspect, an embodiment of the present application also provides a computer-readable storage medium, which stores instructions. When the computer-readable storage medium is run on a communication device, any implementation method in the above-mentioned first to fourth aspects is executed.

[0038] In the thirteenth aspect, an embodiment of the present application further provides a chip system, comprising: a processor for executing any implementation method in the above-mentioned first to fourth aspects.

[0039] In the fourteenth aspect, an embodiment of the present application also provides a communication system, including a terminal device for executing any implementation method of the first aspect, and a first network device for executing any implementation method of the fourth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG1( a ) is a schematic diagram of the architecture of a communication system used in an embodiment of the present application;

[0041] Figure 1(b) shows a schematic diagram of a network device;

[0042] FIG2( a ) is a schematic diagram of an NTN-based communication system architecture used in an embodiment of the present application;

[0043] FIG2( b ) is another schematic diagram of the NTN-based communication system architecture used in an embodiment of the present application;

[0044] FIG2( c ) is another schematic diagram of the NTN-based communication system architecture used in an embodiment of the present application;

[0045] FIG3 is a flow chart of a communication method according to an embodiment of the present application;

[0046] FIG4( a ) is another flow chart of a communication method according to an embodiment of the present application;

[0047] FIG4( b ) is another schematic flow chart of the communication method provided in an embodiment of the present application;

[0048] FIG4( c ) is a schematic diagram of orbital information represented in a Kepler orbit format according to an embodiment of the present application;

[0049] FIG4( d ) is a schematic diagram of orbit information represented by a state vector according to an embodiment of the present application.

[0050] FIG5 is a schematic diagram of the structure of a communication device provided in an embodiment of the present application;

[0051] FIG6 is another structural diagram of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0052] Figure 1(a) is a schematic diagram of the architecture of a communication system used in an embodiment of the present application. The communication system 1000 shown in Figure 1(a) includes a wireless access network 100 and a core network 200. Optionally, the communication system 1000 also includes the Internet 300. The wireless access network 100 may include at least one network device (such as 110a-110c in Figure 1(a)) and may also include at least one terminal device (such as 120a-120i in Figure 1(a)). The terminal device is connected to the network device wirelessly, and the network device is connected to the core network wirelessly or by wire. The core network device and the network device may be independent and different physical devices, or the functions of the core network device and the logical functions of the network device may be integrated into the same physical device, or a physical device may integrate some of the functions of the core network device and some of the functions of the network device. Terminal devices and network devices may be connected to each other via wired or wireless connections. Figure 1(a) is only a schematic diagram. The communication system may also include other network devices, such as wireless relay devices and wireless backhaul devices, which are not shown in Figure 1(a).

[0053] A network device is an access device that connects a terminal device to a communication system via wired or wireless means. A network device can be a base station, an evolved NodeB (eNodeB), a transmission reception point (TRP), a next-generation NodeB (gNB) in a fifth-generation (5G) mobile communication system, a next-generation base station in a sixth-generation (6G) mobile communication system, a base station in a future mobile communication system, or an access node in a wireless fidelity (WiFi) system. It can also be a module or unit that performs some of the functions of a base station, such as a centralized unit (CU) or a distributed unit (DU). The CU here completes the functions of the radio resource control protocol and the packet data convergence protocol (PDCP) of the base station, and can also complete the functions of the service data adaptation protocol (SDAP); the DU completes the functions of the radio link control layer and the medium access control (MAC) layer of the base station, and can also complete the functions of part of the physical layer or all of the physical layer. For detailed descriptions of the above-mentioned protocol layers, please refer to the relevant technical specifications of the 3rd Generation Partnership Project (3GPP). The network device can be a macro base station (such as 110a in Figure 1(a)), a micro base station or an indoor station (such as 110b in Figure 1(a)), a high-altitude platform, an aircraft or a satellite (such as 110c in Figure 1(a)), a relay node or a donor node, etc. The embodiments of the present application do not limit the specific technology and specific device form adopted by the network device.

[0054] A terminal device is a device with wireless transceiver capabilities that can send signals to or receive signals from a network device. Terminal devices include but are not limited to terminal devices, terminals, user equipment (UE), mobile stations, mobile terminals, etc. Terminal devices can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearable, smart transportation, smart city, etc. The terminal device can specifically be a mobile phone, tablet computer, computer with wireless transceiver capabilities, wearable device, vehicle, aircraft, ship, robot, robotic arm, smart home device, etc. The embodiments of this application do not limit the specific technology and specific device form adopted by the terminal device.

[0055] In an embodiment of the present invention, a terminal device may have multiple states. For example, a terminal device may be in a connected state. A terminal device in the connected state may transmit data. A terminal device in the connected state may establish connections with the network device, and between the network device and the core network. A terminal device may also be in a deactivated state. A terminal device in the activated state may quickly establish a connection with the network device once data needs to be transmitted. For example, a terminal device in the activated state may receive a paging message from the network device once data needs to be transmitted. After receiving the paging message, the terminal device may quickly establish a connection with the network device. A terminal device in the deactivated state may not establish a connection with the network device, but a connection may be established between the network device and the core network for the terminal device. A terminal device may also be in an idle state. A terminal device in the idle state may not establish a connection with the network device, and between the network device and the core network.

[0056] Network devices and terminal devices can be fixed or mobile. They can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on water; they can also be deployed on aircraft, balloons, and artificial satellites. The embodiments of this application do not limit the application scenarios of network devices and terminal devices.

[0057] The roles of network devices and terminal devices can be relative. For example, the aircraft or satellite 110c in Figure 1(a) can be configured as a mobile network device. For terminal devices 120i that access the wireless access network 100 through 110c, 110c is a network device. However, for network device 110a, 110c can also be a terminal device, that is, communication between 110a and 110c is carried out through a wireless air interface protocol. Of course, communication between 110a and 110c can also be carried out through an interface protocol between network devices. In this case, relative to 110a, 110c can also be a network device. Therefore, network devices and terminal devices can be collectively referred to as communication devices. 110a-110c in Figure 1(a) can be referred to as communication devices with network device functions, and 120a-120i in Figure 1(a) can be referred to as communication devices with terminal device functions.

[0058] Network devices and terminal devices, network devices and network devices, and terminal devices and terminal devices can communicate through authorized spectrum, unauthorized spectrum, or both; can communicate through spectrum below 6 gigahertz (GHz), spectrum above 6 GHz, or spectrum below 6 GHz and spectrum above 6 GHz simultaneously. The embodiments of the present application do not limit the spectrum resources used for wireless communications.

[0059] In the embodiments of the present application, the functions of the network device may also be performed by a module (such as a chip) in the network device, or by a control subsystem that includes the network device functions. The control subsystem that includes the network device functions here may be a control center in the above-mentioned application scenarios such as smart grid, industrial control, smart transportation, and smart city. The functions of the terminal device may also be performed by a module (such as a chip or a modem) in the terminal device, or by a device that includes the terminal device functions.

[0060] In this application, a network device sends downlink signals or downlink information to a terminal device, and the downlink information is carried on a downlink channel. A terminal device sends uplink signals or uplink information to a network device, and the uplink information is carried on an uplink channel. To communicate with a network device, a terminal device needs to establish a wireless connection with a cell controlled by the network device. The cell with which a terminal device has established a wireless connection is called the serving cell of the terminal device.

[0061] In this application, the numbering of terms is generally for the purpose of convenience in description, and the numbering does not mean that the terms have a difference in order or priority. For example, "first network device" and "second network device", the "first" and "second" are usually only used to distinguish between the two network devices, and should not constitute a limitation on the implementation process of the embodiments of this application.

[0062] Figure 1(b) shows a schematic diagram of a network device. As shown in Figure 1(b), the network device includes one or more CUs, one or more DUs, and one or more radio units (RUs). For clarity, Figure 1(b) shows only one CU, DU, and RU. The CU is connected to the core network and one or more DUs. Optionally, the CU may have some of the core network's functionality. The CU may include a CU-control plane (CP) and a CU-user plane (UP).

[0063] The CU and DU can be configured according to the protocol layer functions of the wireless network they implement: for example, the CU is configured to implement the functions of the PDCP layer and above protocol layers (such as the radio resource control (RRC) layer and / or the SDAP layer, etc.); the DU is configured to implement the functions of the protocol layers below the PDCP layer (such as the radio link control (RLC) layer, the MAC layer, and / or the physical (PHY) layer, etc.). For another example, the CU is configured to implement the functions of the protocol layers above the PDCP layer (such as the RRC layer and / or the SDAP layer), and the DU is configured to implement the functions of the protocol layers below the PDCP layer (such as the RLC layer, the MAC layer, and / or the PHY layer, etc.).

[0064] The above configuration of CU and DU is only an example, and the functions of CU and DU can also be configured as needed. For example, the CU or DU can be configured to have the functions of more protocol layers, or the CU or DU can be configured to have partial processing functions of the protocol layer. For example, some functions of the RLC layer and the functions of the protocol layers above the RLC layer are set in the CU, and the remaining functions of the RLC layer and the functions of the protocol layers below the RLC layer are set in the DU. For another example, the functions of the CU or DU can be divided according to the service type or other system requirements, such as by delay, and the functions whose processing time needs to meet the smaller delay requirement are set in the DU, and the functions that do not need to meet the delay requirement are set in the CU.

[0065] The DU and RU can work together to implement the functions of the PHY layer. A DU can be connected to one or more RUs. The functions of the DU and RU can be configured in various ways according to the design. For example, the DU is configured to implement the baseband function, and the RU is configured to implement the mid-RF function. For another example, the DU is configured to implement the high-layer functions in the PHY layer, and the RU is configured to implement the low-layer functions in the PHY layer or to implement the low-layer functions and the RF functions. The high-layer functions in the physical layer may include a part of the functions of the physical layer, which is closer to the MAC layer, and the low-layer functions in the physical layer may include another part of the functions of the physical layer, which is closer to the mid-RF side.

[0066] As described in the background technology, NTN is introduced into the system architecture of the 5G system and its subsequent evolution. The embodiments of this application are described using the non-terrestrial network device in NTN as a satellite as an example. It should be understood that the non-terrestrial network device in NTN can be other non-terrestrial network devices.

[0067] Generally speaking, satellites can be divided into high-orbit satellites and medium- and low-orbit satellites based on their orbital altitude. High-orbit satellites, also known as geosynchronous orbit (GSO) satellites, move at the same speed as the Earth's rotational system. Therefore, GSO satellites remain stationary relative to the ground. Consequently, GSO satellite cells provide larger coverage, typically with a diameter of 500 kilometers. Low- and medium-orbit satellites, on the other hand, move faster relative to the ground, so their service coverage areas also move accordingly. Accordingly, the cells covered by low- and medium-orbit satellites can be divided into ground quasi-stationary cells and ground mobile cells. Quasi-stationary cells are formed by a moving satellite by adjusting its beam, resulting in a stationary cell position on the ground for a certain period of time. Ground mobile cells, on the other hand, are formed by a satellite that does not dynamically adjust its beam direction. Cells with small beam coverage move with the satellite's movement.

[0068] Satellites can generally be categorized into two types based on their operating mode. The first is transparent, also known as forwarding. In this mode, satellites relay cell information from ground network equipment (such as base stations) or other satellites, primarily forwarding signals. Their functions can include radio frequency filtering, frequency conversion, and / or signal amplification. In this mode, satellites can also function as relays, regenerating and forwarding signals, potentially regenerating and forwarding physical layer signals. The second is regenerative, in which satellites perform all or some of the processing functions of a base station.

[0069] FIG2( a ) is a schematic diagram of an NTN-based communication system architecture provided by an embodiment of the present application. In the system architecture shown in FIG2( a ), at least one satellite can operate in a transparent manner. For example, the communication system can include at least a first satellite 201, a second satellite 202, a first terminal device 211, and a first base station 221. The first satellite 201 and the second satellite 202 both operate in a transparent manner, and both the first satellite 201 and the second satellite 202 can maintain a connection with the first base station 221. The first terminal device 211 can communicate with the first base station 211 via the first satellite 201 during a certain period of time. The first satellite 201 can have a first cell covering the first terminal device 211. Within the first cell, the first terminal device 211 can receive signals from the first satellite 201. The first terminal device 211 establishes a connection with the first base station 211 through the first cell of the first satellite 201 to communicate. The first cell can be the service cell of the first terminal device and can be referred to as the first cell of the first satellite 201. In the method of this embodiment, as the first satellite 201 moves and is unable to cover the first cell, the second satellite 202 can provide the same first cell to serve the first terminal device 211. The first terminal device 211 can switch from the first satellite 201 to the second satellite 202, that is, the first terminal device 211 can switch from communicating with the first base station 221 via the first satellite 201 to communicating with the first base station 221 via the second satellite 202. Similarly, the second satellite 202 can also serve as a relay satellite. The fact that the first satellite 201 and the second satellite 202 have the same cell means that the first base station 221 corresponding to the first cell provided by the first satellite 201 and the first cell provided by the second satellite 202 remain unchanged. In this case, it can be considered that the cell provided by the first satellite 201 and the second satellite 202 for the first terminal device 211 is the same cell, that is, the first cell has not changed. For the first terminal device 211, although the satellite providing communication services has changed, the covered cell remains unchanged. The so-called unchanged cell, or the same first cell provided by the first satellite 201 and the second satellite 202, may mean that the physical cell identifier (PCI) of the cell has not changed, and the PCIs of the first cell provided by the first satellite 201 and the second satellite 202 remain unchanged. In addition, the synchronization signal and physical broadcast signal block (PBCH block, SSB) frequencies transmitted in the same cell may also remain unchanged.

[0070] When the second satellite 202 provides the first cell with coverage for the first terminal device 211, the first terminal device 211 communicates with the first base station 211 via the first cell of the second satellite 202. At this time, the first cell is still the serving cell of the first terminal device and can also be referred to as the first cell of the second satellite 202. It should be understood that the "neighboring cell" or "neighboring cell of the first cell" in the embodiments of the present application refers to the neighboring cell of the serving cell of the terminal device, which can be, for example, the second cell.

[0071] As shown in Figure 2(a), the communication system may further include a second base station 222 and a second terminal device 212. The second base station 222 provides a service cell for the second terminal device 212, i.e., a second cell. The second cell can be considered as a neighboring cell of the first cell, or as a candidate cell for switching by the first terminal device 211. The second cell has a different PCI from the first cell. The second base station 222 and the first base station 221 may be the same base station or different base stations. When the second base station 222 and the first base station 221 are two different base stations, the second base station 222 may communicate with the first base station 221. The second base station 222 may be a satellite or a ground base station, which is not limited here.

[0072] As shown in FIG2(b), another NTN-based communication system architecture diagram is provided in an embodiment of the present application. In this communication system, at least one satellite can operate in a regenerative form. Exemplarily, the communication system described in FIG2(b) includes a first satellite 203 and a second satellite 204, and a first terminal device 213, and the first satellite 203 and the second satellite 204 both operate in a regenerative form. Similar to the communication system described in FIG2(a), the first satellite 203 and the second satellite 204 can both provide a first cell covering the first terminal device 213, and the relationship between the first satellite 203 and the second satellite 204 and the first cell can refer to the description of the relationship between the first satellite 201, the second satellite 202 and the first cell covering the first terminal device 211 in FIG2(a). The first terminal device 213 communicates directly with the first satellite 203 or the second satellite 204. Similarly, a first terminal device 213 can communicate with a first satellite 203 during a certain period of time. The first terminal device 213 accesses a first cell via the first satellite 203. This first cell can be referred to as the serving cell of the first terminal device 213 and the first cell of the first satellite 203. As the first satellite 203 moves, the first satellite 203 may no longer cover the first cell. At this point, the second satellite 204 can cover the first cell. The first terminal device 213 can then switch from the first satellite 203 to the second satellite 204. After the switch, the first terminal device 213 communicates with the second satellite 204 and accesses the first cell via the second satellite 204. The first cell remains the serving cell of the first terminal device 213 and the first cell can be referred to as the first cell of the second satellite 204. For the first cell, the PCI corresponding to the first cell may not change before and after the switch. Similarly, the communication system as shown in Figure 2(b) can also include a second terminal device 214 and a second base station 223, a second cell, etc. The second cell can be considered as a neighboring cell of the first cell, and can also be used as a candidate cell for switching of the first terminal device 213, which will not be repeated here.

[0073] As shown in FIG2(c), another NTN-based communication system architecture diagram is provided in an embodiment of the present application. In this architecture, the first satellite 205 and the second satellite 206 have some base station processing functions, such as DU functions, and the first base station 224 deploys the base station CU function. The first terminal device 215 communicates with the first base station 224 through the first satellite 205 or the second satellite 206. Similarly, the communication system described in FIG2(c) may also include a second terminal device 216 and a second base station 225, a first cell, a second cell, etc. The relationship between them can be found in the description of the communication system architecture diagram of FIG2(a) and the communication system architecture diagram of FIG2(b), which will not be repeated here. In the regeneration working mode, there are regeneration satellites that do not have inter-satellite links, that is, there is no inter-satellite link (ISL) between satellites; and regeneration satellites with inter-satellite links, that is, there is an interface between satellites for directly exchanging data, where the inter-satellite link is an Xn port.

[0074] Handover of a terminal device can be categorized as either hard or soft handover. In a hard handover, the time periods during which the first and second satellites provide service to the first cell do not overlap. During a handover, the first satellite first stops providing service to the terminal device through the first cell, and then the second satellite provides service to the terminal device through the first cell. For the terminal device, the terminal device first disconnects from the first satellite (for example, the terminal device disconnects from the first satellite at the moment the first satellite stops providing service to the terminal) and then reconnects to the second satellite. During the handover, the terminal device may experience a link interruption. In a soft handover, the time periods during which the first and second satellites provide service to the first cell overlap. Before the first satellite stops providing service to the terminal device through the first cell, the second satellite begins providing service to the terminal device through the first cell. For the terminal device, the terminal device begins synchronizing with the second satellite before disconnecting from the first satellite, then maintains connections to the cell through both the first and second satellites, and then disconnects from the first satellite. In both handover scenarios, when the satellite changes, the base station does not need to send a Layer 3 handover command to the terminal device in the first cell. The terminal device inherits the radio resource configuration previously configured by the base station for the terminal device. These two handovers are also called satellite switches with resynchronization.

[0075] Taking Figure 2(a) as an example, since the first satellite 201 and the second satellite 202 are located at different locations, for the first terminal device 211, when the first terminal device 211 soft-hands over from the first satellite 201 to the second satellite 202, the signal quality received by the first terminal device 211 from the second satellite 202 may be poor. In this case, if the first terminal device 211 still switches to the second satellite 202, it may cause the first terminal device 211 to fail the wireless link with the second satellite 202. The embodiment of the present application provides a communication method that can reduce the probability of wireless link failure caused by terminal device switching, thereby ensuring communication reliability.

[0076] Figure 3 is a flow chart of a communication method provided by an embodiment of the present application, which can reduce the probability of wireless link failure caused by the terminal device performing a handover. This embodiment is executed by a terminal device or a module (such as a chip) in the terminal device, a first network device or a module (such as a chip) in the first network device, and a module (such as a chip) in the second network device, wherein the terminal device can correspond to the first terminal device in Figure 2 (a), Figure 2 (b) or Figure 2 (c), the first network device can correspond to the first satellite in Figure 2 (a), Figure 2 (b) or Figure 2 (c), and the second network device can correspond to the second satellite in Figure 2 (a), Figure 2 (b) or Figure 2 (c). The following is an example of the terminal device, the first network device and the second network device executing the method.

[0077] Step 301: The terminal device receives instruction information from the first network device.

[0078] The terminal device is currently accessing a first cell through the first network device, where the first cell is referred to as the serving cell of the terminal device. The first network device and the second network device may be the first satellite and the second satellite of the first cell being handed over, respectively. That is, the first network device provides service to the first cell during a first period of time, and the second network device provides service to the first cell during a second period of time, and the first and second periods of time overlap. The PCI of the first cell remains unchanged during the first and second periods of time.

[0079] At this point, the terminal device can receive the instruction information from the first network device. If the first network device is a transparent forwarding satellite, the instruction information is sent by the ground base station to the first network device, which is then forwarded to the terminal device by the first network device. If the first network device is a regenerative satellite, the instruction information is sent directly from the first network device to the terminal device. It should be understood that this application does not limit the NTN communication architecture of the first network device, the second network device, and the terminal device.

[0080] The indication information is used to instruct the terminal device to measure the reference signal of the first cell from the second network device.

[0081] Optionally, the first network device may also send indication information #A to the terminal device, indicating support for soft switching from the first network device accessing the first cell to the second network device accessing the first cell. For example, the first network device sends a first cell support satellite switching indication information requiring resynchronization to the terminal device through a broadcast message, and sends a first moment and a second moment to the terminal device through a broadcast message (for example, before measuring the reference signal of the first cell from the second network device), wherein the first moment indicates the moment when the first network device stops providing services for the first cell, and the second moment indicates the moment when the second network device starts providing services for the first cell, wherein the second moment is less than or equal to the first moment, or the second moment is earlier than or equal to the first moment. The terminal device can measure the signal quality of the reference signal between the second moment and the first moment. In this way, the terminal device can determine when to measure the reference signal of the first cell of the second network device by receiving the first moment and the second moment.

[0082] In one possible implementation manner in which a terminal device receives indication information from a first network device, the terminal device receives measurement configuration information from the first network device, the measurement configuration information including the indication information, the measurement configuration information being used to configure the terminal device to measure a reference signal of a first cell from a second network device, the measurement configuration information also including a measurement object, wherein the measurement object is configured with a frequency point and other information to be monitored by the terminal device. In this way, the terminal device can obtain the indication information by receiving the measurement configuration information without requiring an additional signaling message to receive the indication information, thereby saving signaling messages.

[0083] Optionally, the measurement object may be a measurement object corresponding to the first cell (for the terminal device, it may also be called a serving cell measurement object. The terminal device obtains the signal quality of the first cell based on the measurement object). The terminal device may measure the reference signal of the first cell from the second network device based on the measurement object corresponding to the first cell. The indication information may be added to the measurement object corresponding to the first cell to instruct the terminal device to measure the reference signal of the first cell from the second network device. Optionally, the measurement object may also be other measurement objects. The network device may add the indication information to other measurement objects to instruct the terminal device to measure the reference signal of the first cell from the second network device. The other measurement object may be used only to measure the reference signal of the first cell received through the second network device, or may be used to measure the reference signal of the neighboring cell of the first cell. It should be understood that the reference signal of the first cell from the second network device is the reference signal sent from the second network device through the first cell, and the reference signal of the first cell from the first network device is the reference signal sent from the first network device through the first cell, but the expression form is different.

[0084] Optionally, the measurement configuration information may include report configuration information, and the report configuration indicates the criteria for triggering the measurement report. Among them, the triggered report can be divided into event-triggered report and periodic triggered report, and the configuration of the event-triggered report includes various event categories, threshold values, duration for meeting the trigger conditions, and reference signal types (such as SSB or channel state information reference signal (CSI-RS)), etc. (for example, the A4 event is defined as the signal quality of the neighboring cell being better than a threshold value). Under normal circumstances, the terminal device will not trigger the report immediately after entering the measurement reporting condition, and the measurement report will only be triggered if the measurement reporting condition is continuously met within the duration of meeting the trigger condition. Among them, the periodic triggered report configuration includes the reporting period, the reference signal type, and the whitelist cell list. The report configuration information includes the indication information (for example, the indication information is included in the report configuration information of the A4 event. Thereby instructing the terminal device to treat the first cell from the second network device as a neighboring cell in the A4 event. That is, to determine whether the signal quality of the first cell from the second network device is the threshold value of the A4 event.). For this reporting configuration, the terminal device will evaluate whether the event is satisfied or reported at the second moment and the first moment.

[0085] In another possible implementation manner in which the terminal device receives indication information from the first network device, the indication information may be event-triggered reporting information, which may be used to measure or evaluate the signal quality of the first cell from the second network device. The event-triggered reporting is specifically used to measure or evaluate the signal quality of the first cell from the second network device.

[0086] In another possible implementation manner in which the terminal device receives indication information from the first network device, the indication information may be existing event trigger reporting information, such as A1, A2, A3, A4, A5, or A6 events. When the terminal device performs event measurement corresponding to the time trigger reporting information or performs measurement reporting evaluation (, it considers the first cell of the second network device as a neighboring cell).

[0087] In another possible implementation manner in which the terminal device receives indication information from the first network device, the terminal device receives other configuration information, which includes the indication information. For example, the other configuration information may be an RRC message or a media access control (MAC) control element (CE), and the indication information may be sent to the terminal device via an RRC message or a MAC CE.

[0088] Step 302: The terminal device receives a reference signal of a first cell from a second network device.

[0089] If the second network device is a transparent forwarding satellite, the reference signal is sent by the ground base station to the second network device, and then forwarded to the terminal device by the second network device; if the second network device is a regenerative satellite, the reference signal is sent directly to the terminal device by the second network device.

[0090] Step 303: The terminal device measures a reference signal of the first cell from the second network device.

[0091] After receiving the instruction information from the first network device, the terminal device measures the reference signal of the first cell from the second network device according to the instruction information. The terminal device can measure the reference signal of the first cell from the second network device according to the measurement configuration information received from the first network device.

[0092] As described above, the measurement configuration information may include measurement objects, including synchronization signal and physical broadcast signal block (synchronization signal and PBCH block, SSB) frequency, SSB subcarrier spacing, SSB-based measurement timing configuration (SMTC), whitelist cells and blacklist cells, etc. It should be noted that SSB and SMTC in this application can also be replaced by other names, which are not limited in this application. For example, SSB can be called a reference signal, and SMTC can be called a reference signal measurement timing configuration.

[0093] Each cell periodically transmits multiple SSB beams in the time domain (i.e., SSB beam scanning). To ensure accurate measurement of all SSB beams in each cell, when the base station sends measurement configuration information, it not only indicates the SSB frequency to be measured, but also indicates the time domain location and duration for starting the SSB measurement. This indicates to the terminal device the time window for searching for SSB, which is configured using the SMTC. By configuring the SMTC, the terminal device can be effectively instructed to search for the SSB time window, reducing unnecessary measurement power consumption of the terminal device.

[0094] SMTC represents the timing configuration sent by the base station to a terminal device when performing SSB-based measurements on a cell. This configuration includes the SMTC period (periodicity), SMTC duration (duration), and SMTC offset (offset). For example, the SMTC configuration is given by SMTC1, and the configuration element corresponding to SMTC1 is SSB-MTC, which includes two sub-elements: periodicityAndOffset and duration.

[0095] PeriodicityAndOffset represents the SMTC period (characterizing the repetition period of the measurement action, or the period of the SMTC measurement window), and the SMTC offset (used to determine the measurement window, for example, the starting subframe of the time window in which the UE searches for SSB within the period).

[0096] Duration indicates the duration of the SMTC (indicates the duration of the measurement action after it starts).

[0097] The UE generally uses the timing of the current serving cell as a reference to determine the window in which the UE searches for SSBs in neighboring cells.

[0098] For example, the UE determines the radio frame number (SFN) and subframe number (subframe) of the first subframe of the measurement window corresponding to the current serving cell according to the following formula.

[0099] SFN mod T = (FLOOR (SMTC offset / 10))

[0100] If the SMTC period exceeds 5 subframes, then subframe=SMTC offset mod 10, otherwise subframe=SMTC offset or (SMTC offset+5).

[0101] Where T=CEIL(SMTC period / 10). CEIL() is rounded up.

[0102] Optionally, measurement targets also include whitelisted cells and blacklisted cells. Network devices can configure specific lists of cells to be measured, namely whitelisted cells and blacklisted cells. For cells on the blacklist, the terminal device will no longer perform event measurement or report measurements for those cells. Whitelisted cells, on the other hand, are cells for which the terminal device will perform event measurement and report measurements.

[0103] Optionally, the network device assigns a corresponding measurement object identifier to each measurement object, referred to as MeasObjectId.

[0104] The terminal device can measure the reference signal according to the specific configuration of the above measurement object.

[0105] Optionally, the measurement configuration information may further include measurement quantity configuration information. The measurement quantity configuration information is used to configure the measurement quantity, and the measurement quantity may include:

[0106] Reference signal received power (RSRP), which reflects the received strength of the reference signal;

[0107] Received signal strength indicator (RSSI), which reflects the overall signal strength of the current channel;

[0108] Reference signal received quality (RSRQ), which reflects the signal-to-noise ratio and interference level of the current channel quality, is approximately the ratio of RSRP to RSSI;

[0109] The signal to interference plus noise ratio (SINR) reflects the signal to interference ratio of the current channel and is an important indicator for measuring terminal equipment.

[0110] The terminal device can specify which measurement quantities of the reference signal to measure based on the above measurement quantity configuration information, providing a basis for the subsequent switching strategy. The measurement quantity used in the general switching strategy is mainly based on the measurement of RSRP, RSRQ or SINR as the trigger quantity. Specifically, the terminal device performs measurements according to the measurement configuration information. When the terminal device determines that the trigger report (including event-triggered reporting or periodic triggered reporting) of a certain report configuration is met, the terminal device reports the measurement report. The content of the measurement report includes at least one of the measurement ID MeasId, the service cell measurement result measResultServingMOList, or the neighboring area measurement result measResultNeighCells. Among them, the service cell measurement result includes the physical cell identifier, cell-level measurement results, such as cell-level RSRP, RSRQ or SINR measurement results. The service cell measurement result can also include beam-level measurement results, SSB index or CSI-RS index, beam-level measurement results, such as beam-level RSRP, RSRQ or SINR measurement results. The neighboring cell measurement quantity includes a physical cell identifier, a cell-level measurement result of the neighboring cell, and may also include a beam-level measurement result of the neighboring cell.

[0111] When performing measurements, the terminal device can receive first SMTC information and second SMTC information from the first network device (for example, before measuring the reference signal of the first cell from the second network device), wherein the first SMTC information is used by the terminal device to measure the reference signal of the first cell from the second network device and the reference signal of the neighboring cell, and the second SMTC information is used to measure the reference signal of the neighboring cell or the reference signal of the first cell from the first network device. The terminal device can measure different reference signals based on the first SMTC information and the second SMTC information. That is, the terminal device can measure the reference signal of the first cell of the second network device and the reference signal of the neighboring cell of the first cell based on the first SMTC information; the terminal device can measure the reference signal of the neighboring cell of the first cell based on the second SMTC information.

[0112] The terminal device may also receive a first moment and a second moment from the first network device (for example, before measuring the reference signal of the first cell from the second network device), wherein the first moment indicates the moment when the first network device stops providing services for the first cell, and the second moment indicates the moment when the second network device starts providing services for the first cell, wherein the second moment is less than or equal to the first moment, or the second moment is earlier than or equal to the first moment. The terminal device starts measuring the reference signal of the first cell from the second network device at a moment between the second moment and the first moment.

[0113] The terminal device can also perform different measurements at different moments based on the SMTC information. For example, before the second moment or after the first moment, the terminal device measures the reference signal of the neighboring cell of the first cell based on the second SMTC information, and between the second moment and the first moment, the terminal device measures the reference signal of the first cell of the second network device and the reference signal of the neighboring cell of the first cell based on the first SMTC information. For another example, before the second moment, the terminal device measures the reference signal of the neighboring cell and the reference signal of the first cell from the first network device based on the second SMTC information, or before the second moment, the terminal device only measures the reference signal of the neighboring cell based on the second SMTC information. For another example, between the second moment and the first moment, the terminal device measures the reference signal of the first cell from the second network device and the reference signal of the neighboring cell based on the first SMTC information, or, between the second moment and the first moment, the terminal device measures the reference signal of the first cell from the second network device, the reference signal from the first cell of the first network device and the reference signal of the neighboring cell based on the first SMTC information. It should be understood that between the second moment and the first moment, the terminal device can measure the reference signal of the first cell from the first network device based on the first SMTC information, or can directly measure the reference signal of the first cell from the first network device without based on the first SMTC information.

[0114] Before measuring the reference signal of the first cell from the second network device, the terminal device may also receive a third SMTC from the first network device, wherein the third SMTC information is used by the terminal device to measure the reference signal of the first cell from the second network device. Based on the third SMTC information, the terminal device only measures the reference signal of the first cell from the second network device. It should be noted that the third SMTC may not appear at the same time as the first SMTC. For example, the terminal device receives the second SMTC and the third SMTC from the first network device. The first network device can configure multiple SMTCs (referred to as SMTC set #1) for the terminal device (for example, 4 SMTCs can be configured. The periods and durations of these 4 SMTCs are the same, but the SMTC offsets are different), and these SMTCs are used to measure the reference signal of the neighboring cell of the first cell or the reference signal of the first cell. With respect to the third SMTC, in one embodiment, the first network device sends multiple SMTC configurations to the terminal device in the measurement configuration. The multiple SMTC configurations include the second SMTC and the third SMTC. The first network device sends indication information #C in the measurement configuration information, indicating which SMTC in the multiple SMTC configurations is the third SMTC. For example, the indication information #C indicates which SMTC configuration of the third SMTC in the multiple SMTC configurations is the third SMTC. In another embodiment, a new SMTC is added in the measurement configuration information for measuring the reference signal of the first cell from the second network device, and the SMTC is the third SMTC. Optionally, when the first network device configures the third SMTC for the terminal device, the first network device configures a maximum of 3 SMTCs for the terminal device in the SMTC set #1 for measuring the reference signal of the neighboring cell of the first cell or the reference signal of the first cell. Optionally, the terminal device only uses the third SMTC between the second moment and the first moment. When the terminal device switches to the first cell of the second network device, the terminal device does not use the third SMTC to perform measurements.

[0115] Optionally, between the second moment and the first moment, when the terminal device measures the reference signal of the first cell from the second network device, due to the high-speed mobility of the first network device and the second network device, the time deviation between the reference signal of the first cell from the first network device and the reference signal of the first cell from the second network device reaching the terminal device is dynamically changing, which may cause the previously configured SMTC configuration for measuring the reference signal of the first cell from the second network device to be unreasonable, so the network device can configure the terminal device to measure the propagation delay difference between the terminal device and the first network device and the second network device (for example, the first network device configures the terminal device to measure the propagation delay difference between the terminal device and the first network device and the second network device through RRC message #1). Further optionally, the network device (for example, the first network device) notifies the terminal device to report the propagation delay difference between the terminal device and the first network device and the second network device after the second moment, for example, the first network device carries indication information #E in RRC message #1, instructing the terminal device to report the propagation delay difference between the terminal device and the first network device and the second network device after the second moment. After the terminal device reports the propagation delay deviation (for example, propagation delay difference #1) between the terminal device and the first network device and the second network device to the first network device, when the terminal device detects that the latest propagation delay deviation (for example, propagation delay difference #2) between the terminal device and the first network device and the second network device exceeds a certain threshold (for example, the first network device configures the threshold in RRC message #1) reported by the terminal device before, the terminal device reports the latest propagation delay deviation (for example, propagation delay difference #2) between the terminal device and the first network device and the second network device to the first network device.

[0116] Between the second moment and the first moment, after obtaining the reference signal quality of the first cell from the second network device and the reference signal quality of the first cell from the first network device, the terminal device will respectively maintain the measured reference signal quality of the first cell from the second network device and the reference signal quality of the first cell from the first network device between the second moment and the first moment. Exemplarily, the measurement output of the reference signal is divided into a beam-level measurement result (also referred to as a reference signal-level measurement result, such as a measurement result corresponding to SSB) and a cell-level measurement result. After the physical layer filtering is completed, the beam-level measurement result is obtained, and the beam-level measurement result is input into the radio resource control (RRC) layer for further processing. On the one hand, the RRC layer performs beam merging to obtain a cell-level measurement result, and then filters the cell-level measurement result to obtain the reference signal quality finally used for reporting. On the other hand, after the RRC layer completes the filtering, it can perform beam selection and report the selected beam to the network. The terminal device respectively maintains the measured reference signal quality of the first cell from the second network device and the reference signal quality of the first cell from the first network device between the second moment and the first moment. The terminal device performs physical layer filtering on the reference signal quality of the first cell from the first network device and the reference signal quality of the first cell from the second network device at the physical layer to obtain beam-level measurement results. The beam-level reference signal quality of the first cell of the first network device and the reference signal quality of the first cell of the second network device are then input into the RRC layer for filtering and beam merging, respectively, to obtain the cell-level reference signal quality of the first cell of the first network device and the reference signal quality of the first cell of the second network device. The cell-level reference signal quality of the first cell of the first network device and the reference signal quality of the first cell of the second network device can be used to report to the network. Optionally, the terminal device can also perform beam selection after the RRC completes the filtering, and report the selected reference signal beam of the first cell of the second network device or the reference signal beam of the first cell of the first network device to the network.

[0117] Optionally, when the terminal device determines that the reference signal quality of the first cell from the second network device is relatively poor (for example, when the reference signal quality of the first cell from the second network device is lower than a first threshold), the terminal device does not perform soft handover. That is, for the terminal device, the terminal device needs to wait for the handover configuration or handover command sent by the first network device, or wait for the execution condition of the conditional handover sent by the first network device to be met before handing over to the neighboring cell (such as the second cell).

[0118] Optionally, when the terminal device determines that the reference signal quality of the first cell from the second network device is relatively good (for example, when the reference signal quality of the first cell from the second network device is higher than a first threshold), the terminal device performs soft switching.

[0119] Step 304: The terminal device sends the measured reference signal quality of the first cell from the second network device to the first network device.

[0120] The reference signal quality measured by the terminal device sent to the first network device can be triggered and reported according to a standard for triggering the reporting of the measurement report. For example, the measurement configuration information may include report configuration information, and the report configuration indicates the standard for triggering the reporting of the measurement report. Among them, the triggered report can be divided into event-triggered reporting and periodic triggered reporting. The configuration of event-triggered reporting includes various event categories, threshold values, duration for meeting the trigger conditions, and the type of reference signal (such as SSB or channel state information reference signal (CSI-RS)). Under normal circumstances, the terminal device will not trigger the report immediately after entering the measurement reporting condition. The measurement report will only be triggered if the measurement reporting conditions are continuously met within the duration of meeting the trigger conditions. Among them, the periodic triggered reporting configuration includes the reporting period, the reference signal type, and the whitelist cell list. The terminal device will perform corresponding measurements according to the configuration content, and send measurement reports according to the reporting period and interval. For each report configuration information, the network device will assign a corresponding report configuration identifier (abbreviated as ReportConfigId).

[0121] The network side can configure multiple measurement configuration information. For example, the measurement configuration information also includes a measurement identifier (ID). The measurement ID is used to combine the measurement object and the measurement configuration as a set. As shown below,

[0122] The measurement ID measId links the measurement object identifier MeasObjectId and the measurement report configuration identifier reportConfigId, thereby linking the measurement object and the measurement report configuration. When the terminal device sends a measurement report to the network device, it indicates measId to the network device. The network device can find the corresponding measObjectId and reportConfigId according to the measId, and then determine the measurement report of what event the received measurement report is for. The network device can also link multiple measurement objects to the same measurement report configuration by configuring multiple measIds, and can also link multiple measurement report configurations to the same measurement object. For example, the measurement report sent by the terminal device to the first network device carries the measured reference signal quality of the first cell from the second network device.

[0123] Optionally, the report configuration information of the measurement configuration information may include the indication information in step 301. The terminal device measures the reference signal of the first cell received from the second network device according to the measurement configuration corresponding to the measurement object associated with the report configuration, and reports the measurement result according to the report configuration information. After the terminal device reports the reference signal quality to the first network device, the first network device will perform subsequent processing according to the switching strategy. For example, the first network device may determine whether it is necessary to switch the terminal device to a neighboring cell (such as the second cell) based on the reference signal quality of the first cell received from the second network device. If the reference signal quality of the first cell from the second network device is poor, for example, below a certain threshold, the first network device configures a switching configuration or switching command for the terminal device to switch to a neighboring cell (such as the second cell). If the reference signal quality of the first cell from the second network device is good, for example, not below a certain threshold, the first network device does not need to configure a switching configuration or switching command for the terminal device to switch to a neighboring cell (such as the second cell), and the terminal device switches to access the first cell through the second network device (that is, performs soft switching from the first network device to the second network device).

[0124] The first network device may also send the reference signal quality of the first cell received from the second network device to the third network device, and the third network device determines whether it is necessary to switch the terminal device to a neighboring cell (such as the second cell). If the reference signal quality of the first cell from the second network device is poor, for example, below a certain threshold, the third network device configures a switching configuration or switching command for the terminal device to switch to a neighboring cell (such as the second cell). If the reference signal quality of the first cell from the second network device is good, for example, not below a certain threshold, the third network device does not need to configure a switching configuration or switching command for the terminal device to switch to a neighboring cell (such as the second cell), and the terminal device switches to access the first cell through the second network device (i.e., performs soft switching from the first network device to the second network device).

[0125] Optionally, when the terminal device reports the measurement results in accordance with the report configuration information, it can carry the reference signal quality of the first cell from the second network device in the neighboring cell measurement results (for example, measResultNeighCells), or add an indication information #F for the reference signal quality of the first cell of the second network device in the protocol, indicating the reference signal quality of the first cell from the second network device.

[0126] Optionally, in step 305, the terminal device receives first condition information from the first network device.

[0127] The first condition information includes radio resource configuration information of a first candidate cell (eg, a second cell) and an execution condition for switching to the first candidate cell.

[0128] For the measurement configuration information corresponding to the first condition information, reference may be made to the descriptions in steps 301 to 304 .

[0129] Optionally, when the first conditional handover is a time-based conditional handover, the time range [T1, T2] in the time-based conditional handover may include a time range between the second moment and the first moment. For example, T1 is the same as the second moment, and T2 is the same as the first moment. The terminal device may measure the reference signal of the first cell received from the second network device within the [T1, T2] time period, and does not need to measure the reference signal of the first cell received from the second network device outside the [T1, T2] time period.

[0130] Optionally, the [T1, T2] configured by the first network device or the third network device for different terminal devices may be different. For example, different terminal devices may access the first cell through the second network device in different time periods.

[0131] The terminal device evaluates whether the execution conditions for switching to the first candidate cell are met. When the execution conditions are met, the terminal device executes the conditional switching, that is, switches to the first candidate cell (adopts the wireless resource configuration information of the first candidate cell and accesses the first candidate cell).

[0132] Optionally, in step 306, the terminal device receives second condition information from the first network device.

[0133] The second condition information is used to instruct the terminal device to perform conditional switching of the first candidate cell according to the first condition information when the measured reference signal quality of the first cell from the second network device is lower than the first threshold.

[0134] Optionally, the second condition information may be included in the first condition information in step 305. For example, the second condition information may be that the serving cell signal quality in the event reporting condition in the first condition information is lower than the first threshold. The measurement configuration information corresponding to the execution condition or the first condition information may carry indication information #B, indicating that the event reporting condition in the first condition switching is that the first cell signal quality received by the second network device is lower than the first threshold.

[0135] Exemplarily, the terminal device determines whether the measured reference signal quality of the first cell from the second network device is lower than the first threshold according to the indication of the second condition information. When the reference signal quality of the first cell from the second network device is lower than the first threshold, the terminal device performs conditional switching of the first candidate cell according to the received first condition information. If the execution condition of the first condition information is met, the terminal device switches to the first candidate cell.

[0136] It should be noted that the present application is not limited to the sequence between the terminal device measuring whether the reference signal quality of the first cell from the second network device is lower than the first threshold and the terminal device evaluating whether the execution conditions for switching to the first candidate cell are met. In one implementation, when the reference signal quality of the first cell from the second network device is lower than the first threshold, the terminal device starts to evaluate whether the execution conditions for switching to the first candidate cell are met. When the execution conditions for switching to the first candidate cell are met, the terminal device executes the conditional switching, that is, switches to the first candidate cell (adopting the wireless resource configuration information of the first candidate cell and accessing the first candidate cell). In another implementation, when the execution conditions of the first conditional information are met, the terminal device starts to evaluate whether the reference signal quality of the first cell from the second network device is lower than the first threshold. When the reference signal quality of the first cell from the second network device is lower than the first threshold, the terminal device executes the conditional switching, that is, switches to the first candidate cell (adopting the wireless resource configuration information of the first candidate cell and accessing the first candidate cell). In another implementation, upon receiving the first conditional information, the terminal device initiates an evaluation of whether the execution conditions for switching to the first candidate cell are met. Upon receiving the second conditional information, the terminal device evaluates whether the reference signal quality of the first cell from the second network device is below a first threshold. When both conditions are met, the terminal device performs the conditional switching, i.e., switches to the first candidate cell (adopts the radio resource configuration information of the first candidate cell and accesses the first candidate cell).

[0137] Optionally, when executing steps 305 and 306, step 304 is optional.

[0138] In an embodiment of the present application, based on the method of the embodiment of Figure 3, the terminal device measures the reference signal quality of the first cell from the second network device according to the indication information, and sends the reference signal quality to the network device. Based on the reference signal quality, the probability of wireless link failure caused by the terminal device performing switching can be reduced. Furthermore, according to the above scheme, after the network device receives the reference signal, the switching strategy of the terminal device can be determined according to the quality of the reference signal. For example, if the network device determines that the quality of the reference signal is poor, it can instruct the terminal device not to continue switching to access the first cell through the second network device, or it can instruct the terminal device to switch to other cells with good signals, such as the neighboring cell of the first cell (the second cell).

[0139] Figure 4(a) is a flow chart of another communication method provided in an embodiment of the present application. This embodiment is executed by a terminal device or a module (such as a chip) in a terminal device, and a first network device or a module (such as a chip) in the first network device. The following is an example of the terminal device, the first network device, and the second network device executing the method.

[0140] The method comprises the following steps:

[0141] Step 401a: The terminal device receives a first time and a second time from a first network device.

[0142] The first time indicates the time when the first network device stops providing services for the first cell, and the second time indicates the time when the second network device starts providing services for the first cell, wherein the second time is less than or equal to the first time. The relationship between the first cell, the first network device, and the second network device can be seen in the description of the embodiment of FIG3 and will not be repeated here.

[0143] Different from the embodiment of FIG. 3 , the terminal device in this embodiment is a terminal device in a deactivated state or an idle state of the first cell, and the first network device and the second network device provide coverage services for the first cell at the same time.

[0144] For a terminal device residing in the first cell via the first network device, measurement of a reference signal sent by the second network device may be initiated at a time between the second time and the first time. When the reference signal sent by the second network device is better than a second threshold, the terminal device may change to residing in the first cell via the second network device. Optionally, the first network device may send the value of the second threshold to the terminal device via a broadcast message.

[0145] Step 402a: The terminal device receives the second indication information.

[0146] Optionally, the second indication information is used to instruct the terminal device not to access or reside in the first cell through the second network device between the second moment and the first moment.

[0147] Optionally, the second indication information is used to indicate that the second network device is the target network device of the first cell. Between the second moment and the first moment, the terminal device does not access or reside in the first cell through the second network device.

[0148] The terminal device may receive the second indication information through the first network device. Optionally, when the terminal device resides in the first cell through the first network device, the terminal device does not change to reside in the first cell through the second network device between the second moment and the first moment, but instead chooses to access the first cell through the first network device. In this case, the terminal device may receive the first moment and the second moment through the first network device.

[0149] Optionally, the terminal device may also receive the second indication information through a second network device. The second network device may send the second indication information to the terminal device by broadcasting. The second network device may also broadcast information of the first network device, such as the ephemeris information of the first network device, the reference signal configuration corresponding to the first network device (such as the index of the reference signal), etc. When the terminal device is just turned on within the coverage area of ​​the first cell, the terminal device receives a signal from the second network device. In this case, the terminal device will not access the first cell through the second network device between the second moment and the first moment according to the second indication information, but will choose to access the first cell through the first network device.

[0150] In one possible implementation, a third network device provides services to a second cell, which is a neighboring cell of a first cell. The third network device sends third indication information to terminal devices in the second cell. The third indication information indicates that the first cell will provide services simultaneously through the first network device and the second network device between a second moment and a first moment, or indicates that the first cell will simultaneously provide services to the first cell through the first network device and the second network device between the second moment and the first moment. The third indication information includes the second moment and the first moment. Terminal devices residing in the second cell will not reside in the first cell through the second network device between the second moment and the first moment. Optionally, the third indication information is also used to indicate the ephemeris information and / or reference signal configuration (for example, the index of the reference signal) corresponding to the first cell on the first network device, or to indicate the ephemeris information and / or reference signal configuration (for example, the index of the reference signal) corresponding to the first cell on the second network device, so that the terminal device residing in the second cell knows which reference signals of the first cell are sent through the first network device and which reference signals of the first cell are sent through the second network device based on the reference signal configuration corresponding to the first cell on the first network device or the reference signal configuration corresponding to the second network device, so that the terminal device residing in the second cell can know whether the received reference signal of the first cell is sent through the first network device.

[0151] Step 403a: The terminal device determines not to access or reside in the first cell through the second network device between the second moment and the first moment based on the second indication information.

[0152] Optionally, the terminal device in the first cell determines to access the first cell through the first network device between the second moment and the first moment based on the second indication information.

[0153] Optionally, for the terminal devices in the idle or inactive state of the second cell (the terminal devices of the second cell may also be in the connected state), only the reference signal sent by the first cell through the first network device is measured before the second moment, and after the first moment, only the reference signal sent by the first cell through the second network device is measured, and between the second moment and the first moment, both the reference signal sent by the first cell through the first network device and the reference signal sent by the first cell through the second network device are measured, or only the reference signal sent by the first cell through the first network device is measured between the second moment and the first moment. This ensures that when there are two network devices providing services simultaneously in the first cell, the terminal devices of the second cell measure the reference information of the neighboring cell through the corresponding network device in different time periods, thereby enabling more accurate neighboring cell measurements.

[0154] In an embodiment of the present application, the method based on the embodiment of Figure 4(a) can ensure that all terminal devices in the first cell between the second moment and the first moment access or reside in the first cell through the first network device, thereby avoiding some terminal devices accessing or residing in the first cell through the first network device, and some terminal devices accessing or residing in the first cell through the second network device, resulting in interference between terminal devices in the same cell.

[0155] It is understood that in order to implement the functions in the above embodiments, the terminal device or the first network device includes hardware structures and / or software modules corresponding to the execution of each function. It should be readily apparent to those skilled in the art that, in combination with the units and method steps of the various examples described in the embodiments disclosed in this application, this application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in hardware or in a manner driven by computer software depends on the specific application scenario and design constraints of the technical solution.

[0156] Figure 4(b) is a flow chart of another communication method provided in an embodiment of the present application. This embodiment is executed by a terminal device or a module (such as a chip) in a terminal device, a first network device or a module (such as a chip) in a first network device, and a second network device or a module (such as a chip) in a second network device. The following is an example of the terminal device, the first network device, and the second network device executing the method.

[0157] The method comprises the following steps:

[0158] Step 401b: The terminal device receives a first moment from the first network device.

[0159] Optionally, the terminal device also receives a second moment from the first network device.

[0160] The relationship between the first moment, the second moment, the first cell, the first network device, and the second network device can be found in the description of the embodiment of FIG3 and will not be repeated here. The terminal device can be in a connected state, a deactivated state, or an idle state, and the state of the terminal device is not limited here.

[0161] Optionally, the first moment and the second moment can be carried in the system information (for example, system information 19) from the first network device. The terminal device receives the system information from the first network device, thereby obtaining the first moment and the second moment. The system information can also carry auxiliary information corresponding to the second network device. The auxiliary information may include ephemeris information, the epoch time of the ephemeris information, the effective length of the ephemeris information, etc. Optionally, the system information can also carry indication information #D, indicating support for satellite switching that requires resynchronization (that is, when the satellite changes but the PCI of the cell remains unchanged, the first network device supports the switching command without sending a layer 3 to the terminal device of the first cell). Optionally, the indication information #D can also include auxiliary information corresponding to the second network device.

[0162] The epoch time of the ephemeris information corresponding to the second network device indicates the system frame number and subframe number. That is, the ephemeris information of the second network device refers to the position of the second network device at that epoch time. Based on the position of the second network device at that epoch time, the terminal device can calculate the current position of the second network device. The system frame number indicated in the epoch time indicates the current system frame or the next system frame at the time the terminal device received the system information, or the system frame number indicated in the epoch time indicates the system frame closest to the system frame at the time the terminal device received the system information.

[0163] Optionally, the system information sent by the first network device also includes auxiliary information corresponding to the neighboring cell of the first cell of the second network device.

[0164] Ephemeris information, also known as orbital information, refers to the operating path information of non-terrestrial network devices associated with the cell, and can also be referred to as ephemeris information of non-terrestrial network devices associated with the cell. The method for determining ephemeris information can be shown in Figure 4(c) or Figure 4(d), where Figure 4(c) is a schematic diagram of orbital information represented in a Kepler orbit format according to an embodiment of the present application, and Figure 4(d) is a schematic diagram of orbital information represented in a state vector according to an embodiment of the present application.

[0165] The parameters shown in Figure 4(c) include orbit-level parameters, such as i0, the inclination angle, Ω0, the longitude of the ascending node in the orbital plane, and ω, the perigee angular distance. These orbit-level parameters are used to determine the orbit. The parameters shown in Figure 4(d) include satellite-level parameters used to determine the satellite's position, such as M0, the mean anomaly angle at epoch time.

[0166] When the state vector is used to represent the orbital information, the velocity vector in the state vector, such as (v x ,v y ,v z), etc., and rate and reference point information must be provided for non-synchronous satellites. The position coordinate system based on the state vector can be a latitude and longitude coordinate system (λ, ψ, h) as shown in Figure 4(d) or an Earth-centered Earth-fixed coordinate system (X, X, Z), etc., and the embodiments of this application are not limited to this.

[0167] Step 402b: The terminal device is synchronized with the first cell through the second network device.

[0168] For a hard handover, the terminal device starts downlink synchronization with the first cell via the second network device at the first moment. For a soft handover, the terminal device performs downlink synchronization with the first cell via the second network device between the second moment and the first moment (e.g., after any moment between the second moment and the first moment).

[0169] The terminal device starts a timer #1 at the subframe time indicated by the epoch time of the ephemeris information of the second network device received from the system information of the first network device. The length of the timer is the valid length of the ephemeris information of the second network device received from the system information received from the first network device.

[0170] Step 403b: The terminal device receives system information from the second network device.

[0171] The terminal device obtains system information (for example, system information 19) from the second network device. Optionally, the terminal device obtains the system information of the second network device after performing downlink synchronization with the first cell through the second network device. For example, the terminal device can obtain the system information of the second network device without waiting for timer #1 to time out after performing downlink synchronization with the first cell through the second network device, or the terminal device obtains the system information of the second network device after performing downlink synchronization with the first cell through the second network device and waiting for timer #1 to time out. The system information sent by the second network device includes the corresponding auxiliary information in the second network device. When the terminal device obtains the system information sent by the second network device, the terminal device starts or restarts timer #1 at the subframe time indicated by the epoch time of the ephemeris information of the second network device received from the system information of the second network device, and the length of the timer is the valid length of the ephemeris information of the second network device received in the system information received from the second network device.

[0172] The terminal device initiates a random access process in the first cell of the second network device, or the terminal device does not need to initiate a random access process in the first cell of the second network device and directly performs data transmission (that is, the terminal device sends and receives data according to the pre-configured authorization sent by the first network device or the terminal device monitors the downlink physical control channel sent by the second network device to obtain authorization to send and receive data).

[0173] Optionally, if before the terminal device obtains the system information of the second network device in step 403b, the terminal device can use the auxiliary information corresponding to the neighboring area of ​​the first cell in the second network device obtained in step 401b to perform measurement of the neighboring area of ​​the first cell.

[0174] It should be noted that the present application does not limit the order of uplink and downlink synchronization, starting the timer, and obtaining the system information of the second network device.

[0175] In the embodiment of the present application, the method based on the embodiment of FIG. 4( b ) can ensure that, after the terminal device synchronizes to the first cell via the second network device, it can promptly obtain the ephemeris information of the second network device sent by the second network device, thereby ensuring the handover performance of the terminal device. Furthermore, the terminal device can promptly obtain the ephemeris information of the neighboring cells of the first cell of the second network device, thereby promptly measuring the neighboring cells of the first cell, thereby ensuring the handover performance of the terminal device. In addition, by promptly obtaining the ephemeris information of the second network device, the terminal device can maintain the ephemeris information of the second network device using the system frame number and subframe number of the first cell in the second network device, thereby reducing the complexity of the terminal device.

[0176] Figures 5 and 6 are schematic diagrams of the structures of possible communication devices provided in embodiments of the present application. These communication devices can be used to implement the functions of the terminal device or the first network device in the above method embodiments, thereby also achieving the beneficial effects of the above method embodiments. In the embodiments of the present application, the communication device can be a terminal device or a first network device, or a module (such as a chip) applied to the terminal device or the first network device.

[0177] The communication device 500 shown in Figure 5 includes a processing unit 510 and a transceiver unit 520. The communication device 500 is used to implement the functions of the terminal device or the first network device in the method embodiment described in Figure 3, Figure 4(a) or Figure 4(b).

[0178] When the communication device is used to implement the functions of the terminal device in the above method embodiment, the transceiver unit 520 is used to receive indication information from the first network device, and the terminal device accesses the first cell through the first network device. The indication information is used to instruct the terminal device to measure the reference signal of the first cell from the second network device. The transceiver unit 520 is also used to receive the reference signal of the first cell from the second network device and send the signal quality of the reference signal of the first cell of the second network device to the first network device; the processing unit 510 is used to measure the reference signal of the first cell of the second network device.

[0179] In one possible implementation, the transceiver unit 520 is further used to receive a first moment and a second moment from the first network device, where the first moment indicates the moment when the first network device stops providing services for the first cell, and the second moment indicates the moment when the second network device starts providing services for the first cell, wherein the second moment is earlier than or equal to the first moment; the processing unit 510 is further used to switch from accessing the first cell through the first network device to accessing the first cell through the second network device at a third moment, and the third moment is between the second moment and the first moment.

[0180] In one possible implementation, the transceiver unit 520 is also used to receive measurement configuration information from the first network device, where the measurement configuration information includes the above-mentioned indication information. The measurement configuration information is used to configure the terminal device to measure a reference signal. The measurement configuration information includes a measurement object and report configuration information, where the measurement object is a measurement object corresponding to the first cell.

[0181] In one possible implementation, the transceiver unit 520 is also used to receive first SMTC information and second SMTC information from the first network device, wherein the first SMTC information is used to measure the reference signal of the first cell of the second network device and the reference signal of the neighboring cell of the first cell, and the second SMTC information is used to measure the reference signal of the neighboring cell of the first cell.

[0182] In one possible implementation, the transceiver unit 520 is further used to receive first condition information from the first network device, where the first condition information includes wireless resource configuration information of the first candidate cell and the execution conditions for switching to the first candidate cell; the transceiver unit 520 is further used to receive second condition information from the first network device, where the second condition information is used to indicate that when the measured signal quality of the reference signal of the first cell of the second network device is lower than the first threshold, conditional switching of the first candidate cell is performed.

[0183] In one possible implementation, the processing unit 510 is further used to measure the reference signal of the neighboring cell of the first cell based on the second SMTC information before the second moment or after the first moment; and between the second moment and the first moment, measure the reference signal of the first cell of the second network device and the reference signal of the neighboring cell of the first cell based on the first SMTC information.

[0184] In a possible implementation, the processing unit 510 is further configured to measure the signal quality of the first cell from the second network device between the second time and the first time, and to measure the signal quality of the first cell from the first network device between the second time and the first time.

[0185] In a possible implementation, the processing unit 510 is further configured to respectively maintain the measured signal quality of the first cell of the second network device and the measured signal quality of the first cell of the first network device between the second moment and the first moment.

[0186] When the communication device 500 is used to implement the function of the first network device in the above method embodiment, the transceiver unit 520 is used to send indication information to the terminal device, where the indication information is used to instruct the terminal device to measure the reference signal of the first cell from the second network device, where the first cell is the cell accessed by the terminal device through the first network device; the transceiver unit 520 is also used to receive the signal quality of the reference signal from the terminal device.

[0187] In one possible implementation, the transceiver unit 520 is also used to send a first moment and a second moment to the terminal device, where the first moment indicates the moment when the first network device stops providing services for the first cell, and the second moment indicates the moment when the second network device starts providing services for the first cell, wherein the second moment is less than or equal to the first moment; and the third moment is between the second moment and the first moment, and the third moment is the moment when the terminal device switches from accessing the first cell through the first network device to accessing the first cell through the second network device.

[0188] In one possible implementation, the transceiver unit 520 is also used to send measurement configuration information to the terminal device, where the measurement configuration information includes indication information, and the measurement configuration information is used to configure the terminal device to measure a reference signal. The measurement configuration information includes a measurement object and report configuration information, where the measurement object is the measurement object corresponding to the first cell.

[0189] In one possible implementation, the transceiver unit 520 is also used to send first SMTC information and second SMTC information to the terminal device, wherein the first SMTC information is used to measure the reference signal of the first cell of the second network device and the reference signal of the neighboring cell, and the second SMTC configuration information is used to measure the reference signal of the neighboring cell.

[0190] In one possible implementation, the transceiver unit 520 is also used to send first condition information to the terminal device, where the first condition information includes wireless resource configuration information of the first candidate cell and the execution conditions for switching to the first candidate cell; the transceiver unit 520 is also used to send second condition information to the terminal device, where the second condition information is used to indicate that when the measured signal quality of the reference signal of the first cell of the second network device is lower than the first threshold, conditional switching of the first candidate cell is performed.

[0191] For a more detailed description of the processing unit 510 and the transceiver unit 520, reference can be made to the relevant description in the above method embodiment, which will not be repeated here.

[0192] The communication device 600 shown in Figure 6 includes a processor 610 and an interface circuit 620. The processor 610 and the interface circuit 620 are coupled to each other. It is understood that the interface circuit 620 can be a transceiver or an input / output interface. Optionally, the communication device 600 may also include a memory 630 for storing instructions executed by the processor 610, or storing input data required by the processor 610 to execute instructions, or storing data generated after the processor 610 executes instructions.

[0193] When the communication device 600 is used to implement the above method embodiment, the processor 610 is used to implement the functions of the above processing unit 510 , and the interface circuit 620 is used to implement the functions of the above transceiver unit 520 .

[0194] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or may be 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.

[0195] 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 random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, mobile hard disks, 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 write information to the storage medium. Of course, the storage medium can also be an integral part of the processor. The processor and storage medium can be located in an ASIC. In addition, the ASIC can be located in a terminal device or a network device. Of course, the processor and storage medium can also exist as discrete components in an access network device or a terminal.

[0196] In the above embodiments, all or part of the embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented using software, all or part of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer programs or instructions. A computer program (English: Computer Program) refers to a set of instructions that instruct an electronic computer or other device with message processing capabilities to perform each step of the operation, usually written in a certain programming language and running on a certain target architecture. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are executed in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable device. The computer program or instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer program or instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center via wired or wireless means. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium, such as a floppy disk, a hard disk, or a magnetic tape; an optical medium, such as a digital video disk; or a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both volatile and non-volatile types of storage media.

[0197] In the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0198] In this application, "at least one" means one or more, and "more" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. In the text description of this application, the character " / " generally indicates that the previous and next related objects are in an "or" relationship; in the formulas of this application, the character " / " indicates that the previous and next related objects are in a "division" relationship.

[0199] It is understood that the various numbers used in the embodiments of this application are merely for ease of description and are not intended to limit the scope of the embodiments of this application. The order of the sequence numbers of the above-mentioned processes does not necessarily imply a specific order of execution; the order of execution of the processes should be determined by their functions and inherent logic.

Claims

1. A communication method, characterized in that, Executed by a terminal device or a chip for the terminal device, including: Receiving a first time from a first network device; Performing downlink synchronization with a first cell through a second network device at the first time; After performing downlink synchronization with the first cell through the second network device, obtaining system information of the second network device.

2. The method according to claim 1, wherein The method further includes: Before the first time, accessing the first cell through the first network device, and after the first time, accessing the first cell through the second network device.

3. The method according to claim 1 or 2, characterized in that The method further includes: Receiving a second time from the first network device, where the second time is the time when the second network device serves the first cell.

4. The method according to claim 3, wherein The method further includes: Performing downlink synchronization with the first cell through the second network device between the second time and the first time.

5. The method according to any one of claims 1 to 4, characterized in that, The system information includes indication information for indicating support for satellite handovers that require resynchronization.

6. The method according to any one of claims 1 to 5, characterized in that The system information includes System Information 19.

7. The method according to any one of claims 1 to 6, characterized in that, The system information includes the subframe time indicated by the epoch time of the ephemeris information of the second network device and the valid length of the ephemeris information of the second network device. A timer is started or restarted at the subframe time, and the length of the timer is the valid length of the ephemeris information of the second network device in the system information.

8. A communication method, characterized in that, Executed by a first network device or a chip for the first network device, including: Sending a first time to a terminal device, where the first time is used for the terminal to perform downlink synchronization with a first cell through a second network device and obtain system messages of the second network after the downlink synchronization; Before the first time, serving the terminal device of the first cell.

9. The method according to claim 8, wherein The method further includes: Sending a second time to the terminal device, where the second time is the time when the second network device serves the first cell.

10. The method according to claim 8 or 9, characterized in that, The system information includes indication information for indicating support for satellite handovers that require resynchronization.

11. The method according to any one of claims 8 to 10, characterized in that, The system information includes System Information 19.

12. The method according to any one of claims 8 to 11, characterized in that, The system information includes the subframe time indicated by the epoch time of the ephemeris information of the second network device and the valid length of the ephemeris information of the second network device. The subframe time is used to start or restart a timer, and the length of the timer is the valid length of the ephemeris information of the second network device in the system information.

13. A communication device, characterized in that, Including a module for executing the method according to any one of claims 1 to 7 or the method according to any one of claims 8 to 12.

14. A communication device, characterized in that, Including a processor; when the communication device runs, the processor executes computer instructions to execute the method according to any one of claims 1 to 7 or execute the method according to any one of claims 8 to 12.

15. A communication device, characterized in that, Including a processor and an interface circuit, where the processor is used to communicate with other devices through the interface circuit and execute the method according to any one of claims 1 to 7 or execute the method according to any one of claims 8 to 12.

16. A computer program product, characterized in that, The computer program product includes instructions that, when run on a processor, cause the processor to execute the method according to any one of claims 1 to 7, or execute the method according to any one of claims 8 to 12.

17. A computer-readable storage medium, characterized in that, The storage medium stores a computer program or instructions that, when executed by a communication device, implement the method according to any one of claims 1 to 7, or the method according to any one of claims 8 to 12.

18. A communication system, characterized in that, It includes a terminal device for executing the method according to any one of claims 1 to 7, and a network device for executing the method according to any one of claims 8 to 12.

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