Communication methods, communication devices, and communication systems

Abstract

To provide a communication method, a communication apparatus, and a communication system.SOLUTION: The method includes determining sleep time information of a terminal device based on satellite coverage information of the terminal device, and sending the sleep time information to the terminal device. The satellite coverage information indicates a time period in which the terminal device is covered by a satellite network (NW) and / or indicates a time period in which the terminal device is not covered by the satellite NW, and a sleep time period corresponding to the sleep time information includes the time period in which the terminal device is not covered by the satellite NW. The sleep time information is determined based on the satellite coverage information of the terminal device, and the sleep time period corresponding to the sleep time information includes the time period in which the terminal device is not covered by the satellite NW, to ensure that the terminal device can sleep as much as possible in the time period in which the terminal device is not covered by the satellite NW, and avoid unnecessary NW connection operations such as cell selection, to reduce power consumption of the terminal device.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This application relates to the field of communication technologies, and in particular, to communication methods, communication devices, and communication systems.

Background Art

[0003] Currently, in some communication scenarios, for example, in massive machine type communications (mMTC) application scenarios, satellite communication is introduced to ensure the network coverage effect of terminal devices. Satellite communication can improve network coverage to a certain extent.

[0004] However, since the satellite is in a moving state, it may be impossible for the terminal device to be covered by the satellite network during a period of time.

Summary of the Invention

[0005] Embodiments of this application provide a communication method, a communication device, and a communication system to reduce the power consumption of a terminal device or a core network device (for example, a mobility management network element) in a satellite-based communication scenario.

[0006] According to a first aspect, embodiments of the present application provide a communication method. The method may be implemented by a mobility management network element or by a module (e.g., a chip) used in a mobility management network element. The method includes the steps of: determining sleep time information for a terminal device based on satellite coverage information for the terminal device, wherein the satellite coverage information indicates periods of time when the terminal device is covered by a satellite network and / or periods of time when the terminal device is not covered by a satellite network, and the sleep time period corresponding to the sleep time information includes periods of time when the terminal device is not covered by a satellite network; and transmitting the sleep time information to the terminal device.

[0007] According to the solution described above, the mobility management network element determines sleep time information based on the satellite coverage information of the terminal device, and the sleep time period corresponding to the sleep time information includes the period during which the terminal device is not covered by the satellite network, in order to ensure that the terminal device sleeps as much as possible during the period when the terminal device is not covered by the satellite network, thereby reducing the power consumption of the terminal device by avoiding unnecessary network connection operations such as cell selection.

[0008] In possible implementations, one or more of the terminal device's eDRX cycle, periodic TAU cycle, or periodic registration cycle are determined based on satellite coverage information, and sleep time information includes the sleep start time, which falls within the eDRX cycle or periodic TAU cycle.

[0009] In possible implementations, the sleep time information may include the sleep start time and sleep end time, or it may include the sleep start time and sleep duration.

[0010] According to the aforementioned solution, during the sleep period corresponding to the sleep time information, the terminal device remains in sleep mode and does not perform services, including skipping periodic TAU, periodic registration, and uplink data transmission, thus reducing the terminal device's power consumption.

[0011] In possible implementations, satellite coverage information is received, or ephemeris information of the satellite cell where the terminal device is located is received, and the satellite coverage information is determined based on the ephemeris information.

[0012] Possible implementation methods determine whether the terminal device's position is fixed or whether the terminal device's movement trajectory is fixed.

[0013] In a possible implementation, when the deregistration timer corresponding to the terminal device expires, it is determined, based on satellite coverage information, that the terminal device is not covered by the satellite network, and it is decided to skip deregistration for the terminal device.

[0014] According to this solution, when a terminal device is not covered by the satellite network, the mobility management network element does not deregister the terminal device. This reduces the switching of the terminal device's status between registered and deregistered, thereby potentially reducing the terminal device's power consumption and frequent signaling interactions with the network.

[0015] According to a second aspect, embodiments of the present application provide a communication method. The method may be implemented by a mobility management network element or by a module (e.g., a chip) used in a mobility management network element. The method includes the steps of determining, based on satellite coverage information of a terminal device, that a terminal device is not covered by a satellite network when a deregistration timer corresponding to the terminal device has expired, the satellite coverage information indicating a period of time during which the terminal device is covered by the satellite network and / or a period of time during which the terminal device is not covered by the satellite network, and determining, in response to the case that the terminal device is not covered by the satellite network, to skip performing deregistration on the terminal device.

[0016] According to this solution, when a terminal device is not covered by the satellite network, the mobility management network element does not deregister the terminal device, thus reducing the switching of the terminal device's status between registered and deregistered, and thereby potentially reducing the terminal device's power consumption. In a possible implementation, first information is transmitted to the terminal device, indicating that when the terminal device has an uplink transmission requirement, the terminal device will perform uplink transmission based on the satellite network coverage status.

[0017] In a possible implementation, the first information is satellite coverage information, and the first information clearly indicates that when a terminal device has an uplink transmission requirement, the terminal device initiates uplink transmission based on the satellite coverage information.

[0018] In possible implementations, satellite coverage information is transmitted to the terminal device, and the first information clearly indicates that the terminal device will initiate uplink transmission based on the satellite coverage information when the terminal device has an uplink transmission requirement.

[0019] In possible implementations, uplink transmission requirements include one or more of the following: periodic TAU, periodic registration, or uplink data transmission.

[0020] In possible implementations, satellite coverage information is received, or ephemeris information of the satellite cell where the terminal device is located is received, and the satellite coverage information is determined based on the ephemeris information.

[0021] Possible implementation methods determine whether the terminal device's position is fixed or whether the terminal device's movement trajectory is fixed.

[0022] According to a third aspect, embodiments of the present application provide a communication method. The method may be implemented by a mobility management network element or by a module (e.g., a chip) used in a mobility management network element. The method includes the steps of: determining satellite coverage information for a terminal device, wherein the satellite coverage information indicates a period of time during which the terminal device is covered by a satellite network and / or a period of time during which the terminal device is not covered by a satellite network; and determining a maximum latency based on the satellite coverage information, wherein the maximum latency indicates the maximum period of time for which the terminal device is to be reached.

[0023] According to the aforementioned solution, the mobility management network element can determine reachability based on the satellite coverage information of the terminal device. If the terminal device is unreachable, the mobility management network element determines the maximum latency based on the satellite coverage information to ensure that the terminal device is not paged when it is not covered by the satellite network. This reduces unnecessary signaling interactions between the mobility management network element and the access network device, avoiding the waste of paging resources on the access network device and the loss of downlink data from the terminal device.

[0024] In possible implementations, the terminal device is determined to be unreachable based on satellite coverage information.

[0025] In possible implementations, satellite coverage information is received.

[0026] In possible implementations, ephemeris information of the satellite cell where the terminal device is located is received, and satellite coverage information is determined based on the ephemeris information.

[0027] In a possible implementation, a paging message is sent to an access network device, which includes identification information for the terminal device and indicates that the terminal device should be paged. The first message is received from the access network device, which includes a paging failure indication and satellite coverage information, where the paging failure indication indicates that the reason for the paging failure is that the terminal device is not covered by the satellite network. Optionally, the paging failure indication further indicates that a mobility management network element needs to perform reachability determination / paging based on the satellite coverage information.

[0028] In a possible implementation, a paging message is sent to an access network device, which includes identification information for the terminal device and indicates that the terminal device should be paged. The first message is received from the access network device, which includes satellite coverage information for the terminal device, indicating that the reason for the paging failure is that the terminal device is not covered by the satellite network. Optionally, the satellite coverage information further indicates that a mobility management network element should perform reachability determination / paging based on the satellite coverage information.

[0029] In a possible implementation method, it is determined that the position of the terminal device is fixed or the movement trajectory of the terminal device is fixed.

[0030] According to a fourth aspect, an embodiment of the present application provides a communication method. The method can be implemented by a terminal device or by a module (such as a chip) used by the terminal device. The method includes receiving first information, where the first information indicates that when the terminal device has an uplink transmission requirement, the terminal device performs uplink transmission based on the satellite network coverage status; when there is an uplink transmission requirement, determining that the terminal device is not covered by the satellite network based on the first information; and determining to skip performing uplink transmission.

[0031] According to the foregoing solution, when the terminal device is not covered by the satellite network, even if there is an uplink transmission requirement, the terminal device skips performing uplink transmission, thereby avoiding unnecessary network connection operations such as cell scanning and cell selection, and reducing the power consumption of the terminal device.

[0032] In a possible implementation method, the first information is satellite coverage information. The satellite coverage information indicates the time period during which the terminal device is covered by the satellite network and / or the time period during which the terminal device is not covered by the satellite network. The first information clearly indicates that when the terminal device has an uplink transmission requirement, the terminal device starts uplink transmission based on the satellite coverage information.

[0033] In possible implementations, satellite coverage information is received. This satellite coverage information indicates the time periods during which the terminal device is covered by the satellite network and / or the time periods during which the terminal device is not covered by the satellite network. The first information clearly indicates that, when the terminal device has an uplink transmission requirement, the terminal device will initiate uplink transmission based on the satellite coverage information.

[0034] In possible implementations, uplink transmission requirements include one or more of the following: periodic TAU, periodic registration, or uplink data transmission.

[0035] According to a fifth aspect, embodiments of the present application provide a communication method. The method may be implemented by a terminal device or a module (e.g., a chip) used in a terminal device. The method includes the steps of: receiving sleep time information, wherein the sleep time period corresponding to the sleep time information includes a period of time when the terminal device is not covered by a satellite network, the sleep time information is determined based on satellite coverage information of the terminal device, the satellite coverage information indicates a period of time when the terminal device is covered by a satellite network and / or a period of time when the terminal device is not covered by a satellite network; and sleeping based on the sleep time information.

[0036] According to the aforementioned solution, terminal devices can reduce power consumption by sleeping as much as possible during periods when they are not covered by the satellite network, and by avoiding unnecessary network connectivity operations such as cell scanning and cell selection.

[0037] In possible implementations, sleep time information includes the sleep start time, which falls within the terminal device's eDRX cycle, the terminal device's periodic TAU cycle, or the terminal device's periodic registration cycle.

[0038] Possible implementations include either a sleep start time and a sleep end time, or a sleep start time and a sleep duration.

[0039] According to a sixth aspect, embodiments of the present application provide a communication method. The method may be carried out by an access network device or by a module (e.g., a chip) used in an access network device. The method includes the steps of: obtaining satellite coverage information or ephemeris information of a satellite cell, wherein the satellite coverage information indicates the time periods during which the satellite cell is covered by the satellite network and / or the time periods during which the satellite cell is not covered by the satellite network; and transmitting the satellite coverage information or ephemeris information of the satellite cell to a mobility management network element.

[0040] In possible implementations, during the N2 interface setup procedure, satellite coverage information or ephemeris information corresponding to the satellite cell of the access network device is transmitted to the mobility management network element.

[0041] In possible implementations, during the terminal device registration procedure, satellite coverage information or ephemeris information for the satellite cell where the terminal device is located is transmitted to the mobility management network element.

[0042] In a possible implementation, a paging message is received from a mobility management network element, the paging message contains the identification information of the terminal device, and the paging message indicates that the terminal device should be paged. Based on the satellite coverage information of the satellite cell where the terminal device is located, it is determined that the satellite cell does not have network coverage. A first message is sent to the mobility management network element, the first message contains a paging failure indication and the satellite coverage information of the satellite cell where the terminal device is located, the paging failure indication indicating that the reason for the paging failure is that the satellite cell is not covered by the satellite network. Optionally, the paging failure indication further indicates that the mobility management network element needs to perform reachability determination / paging based on the satellite coverage information.

[0043] In a possible implementation, a paging message is received from a mobility management network element, the paging message contains identification information for the terminal device, and the paging message indicates that the terminal device should be paged. Based on the satellite coverage information of the satellite cell where the terminal device is located, it is determined that the satellite cell does not have network coverage. A first message is sent to the mobility management network element, the first message contains satellite coverage information for the satellite cell where the terminal device is located, the satellite coverage information for the terminal device is the satellite coverage information for the terminal device, and the satellite coverage information indicates that the reason for the paging failure is that the satellite cell is not covered by the satellite network. Optionally, the satellite coverage information further indicates that the mobility management network element should perform reachability determination / paging based on the satellite coverage information.

[0044] According to a seventh aspect, embodiments of the present application provide a communication method. The method may be carried out by a mobility management network element or by a module (e.g., a chip) used in a mobility management network element. The method includes the steps of determining a periodic TAU cycle of a terminal device based on satellite coverage information of the terminal device and transmitting the periodic TAU cycle to the terminal device, or determining a periodic registration cycle of a terminal device based on satellite coverage information of the terminal device and transmitting the periodic registration cycle to the terminal device, wherein the satellite coverage information indicates a period of time during which the terminal device is covered by a satellite network and / or a period of time during which the terminal device is not covered by a satellite network.

[0045] According to the aforementioned solution, the mobility management network element determines the periodic TAU cycle or periodic registration cycle based on the satellite coverage information of the terminal device, such that the period corresponding to the periodic TAU cycle or periodic registration cycle includes a period during which the terminal device is not covered by the satellite network. This ensures that the terminal device avoids performing the periodic TAU procedure or periodic registration procedure during periods when it is not covered by the satellite network, thereby avoiding unnecessary network connectivity operations such as cell selection and reducing the power consumption of the terminal device.

[0046] In possible implementations, the time period corresponding to a periodic TAU cycle includes a period during which the terminal device is not covered by the satellite network, or the time period corresponding to a periodic registration cycle includes a period during which the terminal device is not covered by the satellite network.

[0047] In possible implementations, indication information is sent to the access network device based on satellite coverage information, and the indication information tells the access network device to perform a procedure to release the terminal device.

[0048] In possible implementations, the first period is determined based on the terminal device's satellite coverage information, and the first period is the period from when the terminal device enters an idle state until when the terminal device enters a sleep state, and the first period is transmitted to the terminal device.

[0049] In possible implementations, the causal value is sent to the terminal device, and the causal value is discontinuous satellite coverage.

[0050] In possible implementations, the causal value further indicates that the terminal device skips performing uplink transmission while in sleep mode.

[0051] In possible implementations, a GUTI reassignment command is sent to the terminal device, and the GUTI reassignment command includes a periodic TAU cycle, or a TAU acceptance message is sent to the terminal device, and the TAU acceptance message includes a periodic TAU cycle.

[0052] In possible implementations, a configuration update command is sent to the terminal device, and the configuration update command includes a periodic registration cycle, or a mobility registration update acceptance message is sent to the terminal device, and the mobility registration update acceptance message includes a periodic registration cycle.

[0053] According to an eighth aspect, embodiments of the present application provide a communication method. The method may be carried out by a terminal device or a module (e.g., a chip) used in a terminal device. The method includes the steps of: receiving a periodic TAU cycle from a mobility management network element; and performing a periodic TAU based on the periodic TAU cycle, wherein the time period corresponding to the periodic TAU cycle includes a time period in which the terminal device is not covered by a satellite network; or receiving a periodic registration cycle from a mobility management network element; and performing a periodic registration based on the periodic registration cycle, wherein the time period corresponding to the periodic registration cycle includes a time period in which the terminal device is not covered by a satellite network.

[0054] According to the aforementioned solution, the time period corresponding to the periodic TAU cycle received by the terminal device, or the time period corresponding to the periodic registration cycle received by the terminal device, includes the time period during which the terminal device is not covered by the satellite network, in order to ensure that the terminal device avoids performing the periodic TAU procedure or periodic registration procedure as much as possible during the time period during which the terminal device is not covered by the satellite network, thereby avoiding unnecessary network connectivity operations such as cell selection and reducing the power consumption of the terminal device.

[0055] In possible implementations, the periodic TAU cycle or periodic registration cycle is determined based on the terminal device's satellite coverage information, which indicates the time periods during which the terminal device is covered by the satellite network and / or the time periods during which the terminal device is not covered by the satellite network.

[0056] In possible implementations, a TAU request is sent to the mobility management network element based on the terminal device's satellite coverage information before a periodic TAU cycle is received from the mobility management network element, or a mobility registration update request is sent to the mobility management network element based on the terminal device's satellite coverage information before a periodic registration cycle is received from the mobility management network element, where the satellite coverage information indicates the time periods during which the terminal device is covered by the satellite network and / or the time periods during which the terminal device is not covered by the satellite network.

[0057] In possible implementations, the first period is received from the mobility management network element, and the first period is the period from when the terminal device enters an idle state until when the terminal device enters a sleep state, and the first period is determined based on the terminal device's satellite coverage information.

[0058] In a possible implementation, the causal value is received from a mobility management network element, and the causal value is discontinuous satellite coverage.

[0059] In possible implementations, the cause value indicates that the terminal device will skip performing uplink transmission while in sleep mode. When an uplink transmission requirement exists, the cause value is used to determine whether to skip performing the uplink transmission.

[0060] According to the ninth aspect, embodiments of the present application provide a communication method. The method may be implemented by an access network device or a module (e.g., a chip) used in an access network device. The method includes the steps of: sending a context release request to a mobility management network element based on satellite coverage information of a terminal device, the context release request being used to request the mobility management network element to release the context of the terminal device, the satellite coverage information indicating a period of time during which the terminal device is covered by the satellite network and / or a period of time during which the terminal device is not covered by the satellite network; receiving a periodic TAU cycle from the mobility management network element and transmitting the periodic TAU cycle to the terminal device, wherein the period of time corresponding to the periodic TAU cycle includes a period of time during which the terminal device is not covered by the satellite network; or receiving a periodic registration cycle from the mobility management network element and transmitting the periodic registration cycle to the terminal device, wherein the period of time corresponding to the periodic registration cycle includes a period of time during which the terminal device is not covered by the satellite network.

[0061] According to the tenth aspect, an embodiment of the present application provides a communication device. The device may be a mobility management network element or a module (e.g., a chip) used in a mobility management network element. The device has the function of implementing any implementation method of the first to third aspects and the seventh aspect. The function may be implemented by hardware or by hardware running corresponding software. The hardware or software includes one or more modules corresponding to the function.

[0062] According to the eleventh aspect, an embodiment of the present application provides a communication device. The device may be a terminal device or a module (e.g., a chip) used in a terminal device. The device has a function that implements any implementation method of the fourth, fifth, or eighth aspect. The function may be implemented by hardware or by hardware running corresponding software. The hardware or software includes one or more modules corresponding to the function.

[0063] According to the twelfth aspect, embodiments of the present application provide a communication device. The device may be an access network device or a module (e.g., a chip) used in an access network device. The device has a function that implements any implementation method of the sixth or ninth aspect. The function may be implemented by hardware or by hardware running corresponding software. The hardware or software includes one or more modules corresponding to the function.

[0064] According to the thirteenth aspect, an embodiment of the present application provides a communication device including a processor and memory. The memory is configured to store computer instructions. When the device is in operation, the processor executes the computer instructions stored in the memory, enabling the device to implement any implementation method of the first through ninth aspects.

[0065] According to the fourteenth aspect, an embodiment of the present application provides a communication device comprising a unit or means configured to carry out a step of any implementation method of the first to ninth aspects.

[0066] According to the 15th aspect, an embodiment of the present application provides a communication device including a processor and an interface circuit. The processor is configured to communicate with another device via the interface circuit and to implement any implementation method of the first to ninth aspects. There is one or more processors.

[0067] According to the sixteenth aspect, an embodiment of the present application provides a communication device including a processor coupled to memory. The processor is configured to invoke a program stored in memory to implement any implementation method of the first through ninth aspects. The memory may be located inside or outside the device. There may be one or more processors.

[0068] According to the 17th aspect, embodiments of the present application further provide a computer-readable storage medium. The computer-readable storage medium stores instructions. Any implementation method of the first to 9th aspects is carried out when the instructions are activated by a communication device.

[0069] According to the 18th aspect, embodiments of the present application further provide a computer program product, which includes a computer program or instructions. Any implementation method of the first to 9th aspects is carried out when the computer program or instructions are operated by a communication device.

[0070] According to the 19th aspect, embodiments of the present application further provide a chip system including a processor, configured to implement any of the implementation methods of the first to sixth aspects.

[0071] According to the 20th aspect, embodiments of the present application further provide a communication system including a mobility management network element and an access network device. The mobility management network element is configured to implement any of the implementation methods of the first to third aspects. The access network device is configured to transmit satellite coverage information of the cell in which the terminal device is located to the mobility management network element.

[0072] According to the 21st aspect, embodiments of the present application further provide a communication system including a mobility management network element and an access network device. The mobility management network element is configured to implement any implementation method of the 7th aspect. The access network device is configured to implement any implementation method of the 9th aspect. [Brief explanation of the drawing]

[0073] [Figure 1(a)] This is a schematic diagram of a 5G network architecture based on a service-based architecture. [Figure 1(b)] This is a schematic diagram of a 5G network architecture based on a point-to-point interface. [Figure 2] This is a schematic flowchart of the communication method according to the embodiment of this application. [Figure 3(a)] This is a schematic diagram of a periodic TAU cycle according to an embodiment of the present application. [Figure 3(b)] This is a schematic diagram of the eDRX cycle according to the embodiment of this application. [Figure 3(c)] This is a schematic diagram of the sleep time period according to the embodiment of this application. [Figure 4] This is a schematic flowchart of the communication method according to the embodiment of this application. [Figure 5] This is a schematic flowchart of the communication method according to the embodiment of this application. [Figure 6] This is a schematic flowchart of the communication method according to the embodiment of this application. [Figure 7] This is a schematic flowchart of the communication method according to the embodiment of this application. [Figure 8] This is a schematic flowchart of the communication method according to the embodiment of this application. [Figure 9] This is a schematic flowchart of the communication method according to the embodiment of this application. [Figure 10] This is a schematic flowchart of the communication method according to the embodiment of this application. [Figure 11]This is a schematic flowchart of the communication method according to the embodiment of this application. [Figure 12] This is a schematic flowchart of the communication method according to the embodiment of this application. [Figure 13(a)] This is a schematic diagram of a periodic TAU cycle or periodic registration cycle according to an embodiment of the present application. [Figure 13(b)] This is another schematic diagram of a periodic TAU cycle or periodic registration cycle according to an embodiment of the present application. [Figure 14] This is a schematic flowchart of the communication method according to the embodiment of this application. [Figure 15] This is a schematic flowchart of the communication method according to the embodiment of this application. [Figure 16(a)] This is a schematic flowchart of the communication method according to the embodiment of this application. [Figure 16(b)] This is a schematic flowchart of the communication method according to the embodiment of this application. [Figure 17] This is a schematic diagram of a communication device according to an embodiment of the present application. [Figure 18] This is a schematic diagram of a communication device according to an embodiment of the present application. [Modes for carrying out the invention]

[0074] To address the challenges of wireless broadband technology and remain at the forefront of 3rd generation partnership project (3GPP) networks, the 3GPP specification organization has developed a next-generation mobile communication system (next-generation system) architecture called the 5th generation (5G) network architecture. The architecture not only supports access to the 5G core network (CN) using radio access technologies defined by the 3GPP specification organization (such as long-term evolution (LTE) access technology or 5G radio access network (RAN) access technology), but also supports access to the core network using non-3GPP access technologies via non-3GPP interworking function (N3IWF) or next-generation packet data gateway (ngPDG).

[0075] Figure 1(a) is a schematic diagram of a 5G network architecture based on a service-based architecture. The 5G network architecture shown in Figure 1(a) may include terminal devices, access network devices, and core network devices. Terminal devices access the data network (DN) using the access network devices and core network devices. The core network device includes, but is not limited to, some of the following network elements: authentication server function (AUSF) network element (not shown), unified data management (UDM) network element, unified data repository (UDR) network element, network repository function (NRF) network element (not shown), network exposure function (NEF) network element (not shown), application function (AF) network element, policy control function (PCF) network element, access and mobility management function (AMF) network element, session management function (SMF) network element, user plane function (UPF) network element, binding support function (BSF) network element (not shown), and network data analysis function (NWDAF) network element (not shown).

[0076] Terminal devices may include user equipment (UE), mobile stations, mobile terminals, etc. Terminal devices can be widely applied to 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 grids, smart furniture, smart offices, smart wearable devices, smart transportation, and smart cities. Terminal devices may include mobile phones, tablet computers, computers with wireless receiver functionality, wearable devices, vehicles, urban air transport vehicles (such as unmanned aerial vehicles or helicopters), ships, robots, robotic arms, smart home devices, etc.

[0077] Access network devices may be radio access network (RAN) devices or wireline access network (FAN) devices. Radio access network devices include 3GPP access network devices, untrusted non-3GPP access network devices, and trusted non-3GPP access network devices. 3GPP access network devices include, but are not limited to, modules or units that complete some functions of a base station, such as evolved LTE NodeBs (eNodeBs), next-generation NodeBs (gNBs) for 5G mobile communication systems, base stations for future mobile communication systems, or central units (CUs) or distributed units (DUs). Untrusted non-3GPP access network devices include, but are not limited to, untrusted non-3GPP access gateways or N3IWF devices, untrusted wireless local area network (WLAN) access points (APs), switches, and routers. Trusted non-3GPP access network devices include, but are not limited to, trusted non-3GPP access gateways, trusted WLAN APs, switches, and routers. Wired access network devices include, but are not limited to, wireline access gateways, fixed telephone network devices, switches, and routers.

[0078] Access network devices and terminal devices may be fixed in place or mobile. Access network devices and terminal devices may be deployed on the ground, including indoors or outdoors, or may be handheld or vehicle-mounted, or may be deployed on water, or may be deployed on an airplane, balloon, or satellite in orbit.

[0079] The AMF network element includes functions such as mobility management and access authentication / authorization. In addition, the AMF network element is further responsible for transmitting user policies between terminal devices and the PCF network element.

[0080] SMF network elements include functions such as performing session management, executing control policies delivered by PCF network elements, selecting UPF network elements, and assigning Internet Protocol (IP) addresses to terminal devices.

[0081] UPF network elements include features such as user plane data transfer, session / flow level-based billing statistics, and bandwidth limiting.

[0082] UDM network elements include functions such as subscription data management and user access authorization.

[0083] UDR network elements include functions such as storing and retrieving subscription data, policy data, application data, and other types of data.

[0084] NEF network elements are configured to support capabilities and event exposure.

[0085] AF network elements forward application-side requirements to the network side, such as QoS requirements or user equipment status event subscriptions. AF network elements may be third-party functional entities or operator-deployed application services, such as IP Multimedia Subsystem (IMS) voice call services.

[0086] PCF network elements implement policy control functions such as session-level or service flow-level billing, QoS bandwidth guarantees and mobility management, and terminal policy determination. PCF network elements include access and mobility management policy control function (AM PCF) network elements and session management policy control function (SM PCF) network elements. AM PCF network elements may provide mobility management policies, and SM PCF network elements may provide session management policies.

[0087] An NRF network element may be configured to provide network element discovery functionality and, based on requests from other network elements, provide network element information corresponding to the network element type. The NRF network element may further provide network element management services, such as network element registration, updating, and unregistration, as well as subscription and push of network element status.

[0088] BSF network elements may provide functions such as BSF service registration / unregistration / renewal, connection detection with NRF network elements, session join information creation, terminal device information retrieval, and session join information queries for duplicate IP addresses.

[0089] The AUSF network element is responsible for authenticating users to determine whether a user or device is authorized to access the network.

[0090] An NWDAF network element is primarily configured to collect data (including one or more of terminal device data, access network device data, core network element data, and third-party application data), to provide data analysis services based on machine learning models, and to output data analysis results about the network, the network management system, and the application for making policy decisions. An NWDAF network element may be a standalone network element or may be located in the same location as another network element. For example, an NWDAF network element may be located within a PCF network element or an AMF network element.

[0091] A DN (Data Network) is a network outside of a carrier network. A carrier network may have access to multiple DNs. Multiple services may be deployed on a DN, and a DN may provide services such as data services and / or voice services to terminals. For example, a DN could be the private network of a smart factory, where sensors installed in the factory's workshops are terminals, and a control server for those sensors is deployed on the DN, and the control server may provide services to the sensors. The sensors can communicate with the control server to obtain commands from the control server and, based on those commands, transmit collected sensor data to the control server. In another example, a DN could be a company's internal network, where employees' mobile phones or computers are terminals, and employees' mobile phones or computers can access information, data resources, etc., on the company's internal network.

[0092] In Figure 1(a), Npcf, Nufr, Nudm, Naf, Namf, and Nsmf are service-based interfaces provided by PCF, UDR, UDM, AF, AMF, and SMF, respectively, and are used to trigger the corresponding service-based operations. N1, N2, N3, N4, and N6 are interface sequence numbers. The meanings of these interface sequence numbers are as follows:

[0093] (1) N1 represents the interface between the AMF and the terminal device and may be configured to transmit non-access stratum (NAS) signaling (e.g., QoS rules from the AMF) to the terminal device.

[0094] (2) N2 represents the interface between the AMF and the access network device, and may be configured to transfer wireless bearer control information from the core network side to the access network device, etc.

[0095] (3) N3 represents the interface between the access network device and the UPF, and is primarily configured to transmit uplink and downlink user plane data between the access network device and the UPF.

[0096] (4) N4 represents the interface between the SMF and the UPF and is configured to transfer information between the control plane and the user plane, including the distribution of forwarding rules from the control plane to the user plane, QoS control rules, traffic statistics rules, etc., and reporting of user plane information.

[0097] (5) N6 represents the interface between the UPF and the DN and is configured to transmit uplink and downlink user data flows between the UPF and the DN.

[0098] Figure 1(b) is a schematic diagram of a 5G network architecture based on point-to-point interfaces. For a description of the functions of the network elements in Figure 1(b), please refer to the description of the functions of the corresponding network elements in Figure 1(a). Further details will not be explained again. The main difference between Figure 1(b) and Figure 1(a) is that the interfaces between control plane network elements in Figure 1(a) are service-based interfaces, while the interfaces between control plane network elements in Figure 1(b) are point-to-point interfaces.

[0099] In the architecture shown in Figure 1(b), the names and functions of the interfaces between network elements are as follows:

[0100] (1) For the meanings of the N1, N2, N3, N4, and N6 interfaces, please refer to the explanation above.

[0101] (2) N5 represents the interface between AF and PCF and may be configured to deliver application service requests and report network events.

[0102] (3) N7 represents the interface between PCF and SMF and may be configured to deliver protocol data unit (PDU) session granularity control policies and service data flow granularity control policies.

[0103] (4) N8 represents an interface between the AMF and the UDM, which is used by the AMF to retrieve subscription and authentication data related to access and mobility management from the UDM, and may also be used by the AMF to register mobility management-related information of terminal devices with the UDM.

[0104] (5) N9 represents the user plane interface between UPFs and is configured to transmit uplink and downlink user data flows between UPFs.

[0105] (6) N10 represents an interface between SMF and UDM, which is used by SMF to retrieve subscription data related to session management from UDM, and may also be used by SMF to register session-related information of terminal devices with UDM.

[0106] (7) N11 represents an interface between the SMF and the AMF and may be configured to transfer PDU session tunnel information between the access network device and the UPF, to transfer control messages to be sent to terminal devices, to transfer radio resource control information to be sent to the access network device, etc.

[0107] (8) N15 represents the interface between PCF and AMF and may be configured to deliver terminal policies and access control-related policies.

[0108] (9)N35 represents an interface between the UDM and the UDR, which can be used by the UDM to retrieve user subscription data information from the UDR.

[0109] (10)N36 represents an interface between the PCF and the UDR, which can be used by the PCF to retrieve policy-related subscription data and application data-related information from the UDR.

[0110] It should be understood that the aforementioned network elements or functions may be network elements of hardware devices, software functions running on dedicated hardware, or virtualization functions instantiated on a platform (e.g., a cloud platform). Optionally, the aforementioned network elements or functions may be implemented by one device, by multiple devices, or as a single functional module within a single device. This is not particularly limited to the embodiments of this application.

[0111] In the embodiments of this application, the mobility management network element may be a mobility management entity (MME) of a 4th generation (4G) network, an AMF network element of a 5G network, or another network element having the functionality of an MME or AMF network element of a future communication system.

[0112] In the embodiments of this application, the access network device may be an access network device for a 4G network (such as an eNB), an access network device for a 5G network (such as a gNB), or another network element in a future communication system that has the functionality of an access network device for a 4G network or a 5G network.

[0113] In embodiments of this application, the policy control network element may be a policy and charging rules function (PCRF) network element of a 4G network, a PCF network element of a 5G network, or another network element having the functionality of a PCRF network element or a PCF network element in a future communication system.

[0114] In the embodiments of this application, the storage network element may be a home subscriber server (HSS) of a 4G network, a UDR network element of a 5G network, or another network element having the functionality of an HSS or UDR network element in a future communication system.

[0115] In the embodiments of this application, the meanings of "periodic tracking area update (TAU)" and "periodic registration" are the same. Periodic TAU is designated as 4G, and periodic registration is designated as 5G.

[0116] In the embodiments of this application, a periodic TAU cycle may be represented by a periodic TAU timer, and a periodic registration cycle may be represented by a periodic registration timer. The periodic TAU timer is designated as 4G, and the periodic registration timer is designated as 5G.

[0117] In the embodiments of this application, the meanings of the detach procedure and the deregistration procedure are the same. The detach procedure is designated as 4G, and the deregistration procedure is designated as 5G.

[0118] In embodiments of this application, the maximum latency may be the downlink buffer period of a 4G network, or the maximum latency of a 5G network, or another parameter including the downlink buffer period or maximum latency of a future communication system.

[0119] mMTC is one of the key application scenarios for 5G networks, primarily aimed at various Internet of Things (IoT) service applications based on cellular networks, such as maritime / land / rail / air transport, oil and gas exploration and measurement, environmental monitoring, and mining development. To meet the aforementioned requirements, in the 4G era, narrowband internet of things (NB-IoT) and enhanced machine type communication (eMTC) (also known as long-term evolution machine type communication (LTE-machine type communication, LTE-M)) were defined by 3GPP.

[0120] However, low Earth orbit satellites are emerging to ensure broader network coverage and achieve even more comprehensive global coverage without blind spots. Low Earth orbit satellites can help NB-IoT / eMTC achieve global IoT coverage and avoid network coverage problems caused by inadequate ground network infrastructure.

[0121] 5G is used as an example. After entering an idle state, terminal devices in the NB-IoT / eMTC scenario may enter a sleep state. In this case, the terminal device maintains coarse synchronization with the AMF on the core network side to ensure that the AMF can sense when the terminal device has entered a sleep state. When downlink data from the terminal device arrives, the UPF notifies the SMF, and then the SMF notifies the AMF. If the AMF finds that the terminal device is still in a sleep state and unreachable, the AMF estimates the maximum latency based on the terminal device's sleep time and returns that maximum latency to the SMF, indicating to the SMF that it will wait based on the maximum latency before performing downlink paging. In addition, the SMF determines the maximum buffer period based on the maximum latency and buffers the terminal device's downlink data based on that maximum buffer period, waiting until the terminal device becomes reachable.

[0122] There are two main power saving methods for terminal devices: power saving mode (PSM) and extended discontinuous reception (eDRX). PSM means that the terminal device enters an idle state and then a sleep state for a period of time until there is an uplink service or periodic registration / periodic TAU. eDRX means that when no service is being transmitted, the terminal device enters a sleep state at a fixed time point and wakes up within a specified time to listen for paging information from the network side. In this case, the terminal device is reachable and can receive paging messages from the network side. Unless otherwise specified, eDRX as discussed herein refers to the idle state eDRX.

[0123] 3GPP has introduced NB-IoT and eMTC into satellite network architectures, so satellites will support 4G NB-IoT and eMTC. 5G satellite architectures have been studied since R16 5G, aiming to harmonize 5G architectures with satellites.

[0124] Unlike surface coverage, satellite coverage is constantly moving because satellites need to orbit the Earth regularly. In R17 5G satellite architecture research, the unique concept of fixed cells covered by the surface is still used. In other words, although cells covered by satellites are moving, surface access network devices map the cells covered by satellites to fixed cells on the surface based on the correspondence between satellite coverage and fixed cells on the surface, ensuring that the cell where the terminal device is located and which is sensed on the core network side is still a fixed cell on the surface.

[0125] In addition, discontinuous coverage may exist in certain surface areas, either at the start of satellite deployment or due to deployment costs. For example, in an oil field located in a desert, one or more satellites may provide network communication services to the oil field for a specific period of time, for instance, while regularly orbiting the Earth and collecting and reporting data from various sensors for oil extraction. In other words, the network communication services provided by satellites to terminal devices on the surface have discontinuous coverage. Therefore, terminal devices may be covered by the satellite network for some periods of time and not for other periods of time.

[0126] Discrete coverage features cause the following problems:

[0127] Problem 1: Terminal devices may not be covered by the satellite network for extended periods. However, eDRX in conventional NB-IoT or eMTC scenarios has a relatively short sleep time and is therefore unsuitable for use in this scenario. In other words, based on the sleep mechanism of eDRX in conventional NB-IoT or eMTC scenarios, when the terminal device is woken up after sleep ends, it may still be in a scenario where the terminal device is not covered by the satellite network.

[0128] Problem 2: When downlink data arrives on the network side, the core network cannot determine whether the terminal device is reachable, making it difficult to guarantee successful paging.

[0129] In embodiments of this application, the satellite coverage information of a terminal device indicates the period of time during which the terminal device is covered by the satellite network, and / or the period of time during which the terminal device is not covered by the satellite network. For example, the satellite coverage information of a terminal device may indicate that the terminal device is not covered by the satellite network from 8:00 a.m. to 9:00 a.m. each day, and / or that the terminal device is covered by the satellite network from 12:00 a.m. to 8:00 a.m. and from 9:00 a.m. to 12:00 a.m. each day. The satellite coverage information of a terminal device may be satellite coverage information corresponding to the location of the terminal device, or satellite coverage information of the satellite cell in which the terminal device is located, or satellite coverage information corresponding to the Tracking Area (TA) in which the terminal device is located. For example, if the terminal device is located in cell 1, the satellite coverage information of the terminal device may be the satellite coverage information of cell 1. As another example, if the terminal device is located in cell 2, the satellite coverage information of the terminal device may be the satellite coverage information of cell 2. Alternatively, the satellite coverage information of the terminal device in the embodiments of this application may be ephemeris information.

[0130] In embodiments of this application, the ephemeris information of a cell is the regularity of rotation of a satellite orbiting the Earth that corresponds to the cell. For example, the ephemeris information includes satellite orbital plane parameters and satellite parameters such as satellite velocity, satellite direction of motion, distance from the satellite orbit to the Earth's surface, and reference time point. The time periods during which a cell is covered by the satellite network and / or the time periods during which a cell is not covered by the satellite network may be known based on the ephemeris information of one or more satellites corresponding to the satellite cell. The satellite coverage information of a cell indicates the time periods during which a cell is covered by the satellite network and / or the time periods during which a cell is not covered by the satellite network. For example, there are three satellite cells under an access network device, namely satellite cell 1, satellite cell 2, and satellite cell 3. In this case, the N2 setup message includes the identification information of satellite cell 1, ephemeris information 1 or satellite coverage information 1 corresponding to satellite cell 1, the identification information of satellite cell 2, ephemeris information 2 or satellite coverage information 2 corresponding to satellite cell 2, the identification information of satellite cell 3, and ephemeris information 3 or satellite coverage information 3 corresponding to satellite cell 3.

[0131] Figure 2 is a schematic flowchart of a communication method according to an embodiment of the present application. The method may be used to solve the aforementioned problem 1. The method includes the following steps:

[0132] Step 201: The mobility management network element determines the sleep time information of the terminal device based on the terminal device's satellite coverage information.

[0133] In the implementation, after the access network device is powered on, it needs to establish a connection with the mobility management network element. A 5G network is used as an example. The interface is an N2 interface. Therefore, the access network device sends an N2 setup message to the mobility management network element. The N2 setup message may carry the identification information of the access network device's satellite cell and the satellite ephemeris information or satellite coverage information corresponding to each satellite cell. Subsequently, when a terminal device registers with the network, the mobility management network element may obtain information about the satellite cell where the terminal device is located. For example, if the terminal device is located in satellite cell 1 of the access network device, the mobility management network element determines that the satellite coverage information for cell 1 is the satellite coverage information for the terminal device. If the mobility management network element receives the satellite ephemeris information corresponding to cell 1 from the access network device, the mobility management network element must first determine the satellite coverage information for cell 1 based on the satellite ephemeris information corresponding to cell 1. Optionally, the mobility management network element may further store satellite coverage information as satellite coverage information for terminal devices accessing the network from cell 1.

[0134] In an alternative implementation, during the process of a terminal device registering with the network, the access network device may transmit satellite ephemeris information or satellite coverage information corresponding to the satellite cell where the terminal device is located to the mobility management network element. For example, the terminal device sends a registration request message to the access network device. After receiving the registration request message, when the access network device transmits the registration request message to the mobility management network element, it further transmits satellite ephemeris information or satellite coverage information corresponding to the satellite cell where the terminal device is located; that is, it adds the satellite ephemeris information or satellite coverage information corresponding to the satellite cell where the terminal device is located to the initial N2 message. If the access network device transmits satellite ephemeris information corresponding to the satellite cell where the terminal device is located, the mobility management network element needs to determine the satellite coverage information of the satellite cell where the terminal device is located based on the ephemeris information. In that case, the mobility management network element uses the cell's satellite coverage information as the terminal device's satellite coverage information.

[0135] In an alternative implementation, a third-party network element, such as an application server outside the core network, a network element dedicated to interacting with satellites, or a network element within the core network dedicated to satellite management, may transmit satellite ephemeris information or satellite coverage information corresponding to the satellite cell where the terminal device is located to the mobility management network element. If the third-party network element transmits satellite ephemeris information corresponding to the satellite cell where the terminal device is located, the mobility management network element must determine the satellite coverage information for the satellite cell where the terminal device is located based on the ephemeris information. In this case, the mobility management network element uses the cell's satellite coverage information as the terminal device's satellite coverage information.

[0136] The sleep time period corresponding to the sleep time information includes the period during which the terminal device is not covered by the satellite network.

[0137] In this implementation, the mobility management network element further determines one or more of the terminal device's eDRX cycle, periodic TAU cycle, or periodic registration cycle based on satellite coverage information, and the sleep time period corresponding to the sleep time information is included in the sleep time range of the eDRX cycle, periodic TAU cycle, or periodic registration cycle. In this implementation, the sleep time information herein includes the sleep start time, which falls within the eDRX cycle, periodic TAU cycle, or periodic registration cycle. Figure 3(a) is a schematic diagram of a periodic TAU cycle. At the start of the periodic TAU cycle, the terminal device performs the periodic TAU procedure to initiate network connectivity, and then enters sleep mode from the sleep start time. In addition, the sleep time period of the terminal device within the periodic TAU cycle includes periods when the terminal device is not covered by the satellite network. Therefore, it is possible to ensure that the terminal device enters sleep mode during periods when it is not covered by the satellite network, and that the terminal device does not perform the periodic TAU procedure during periods without network coverage. This reduces the power consumption of the terminal device. The sleep period is longer than or equal to the period during which the terminal device is not covered by the satellite network. See Figure 3(a). Time T1 is the sleep start time, and time T2 is the sleep end time, which is also the end time of the TAU cycle. The difference between T2 and T1 is equal to the period during which the terminal device is not covered by the satellite network. The sleep time information determined in step 201 is the sleep start time in the example in Figure 3(a). In 4G networks, the procedure is generally called the periodic TAU procedure, and in 5G networks, the procedure is called the periodic registration procedure. Figure 3(b) is a schematic diagram of the eDRX cycle. During the paging time window after the start of the eDRX cycle, the terminal device performs listening based on the DRX cycle, and if there are no network connectivity requirements after the paging time window arrives, the terminal device begins to enter sleep at the sleep start time.In addition, the sleep period of a terminal device during the eDRX cycle includes the period during which the terminal device is not covered by the satellite network. Therefore, it is possible to ensure that the terminal device enters sleep mode during the period during which it is not covered by the satellite network, and that the terminal device does not wake up during the period during which it is not covered by the satellite network to listen for paging messages. This reduces the power consumption of the terminal device. The sleep period is longer than or equal to the period during which the terminal device is not covered by the satellite network. See Figure 3(b). Time T1 is the sleep start time, and time T2 is the sleep end time, which is also the end time of the eDRX cycle. The difference between T2 and T1 is longer than or equal to the period during which the terminal device is not covered by the satellite network. The sleep time information determined in step 201 includes the sleep start time in the example in Figure 3(b).

[0138] In an alternative implementation, sleep time information includes a sleep start time and a sleep end time, and the sleep period between the sleep start time and the sleep end time includes the period during which the terminal device is not covered by the satellite network. Alternatively, sleep time information may include a sleep start time and a sleep period, and the sleep end time may be obtained based on the sleep start time and sleep period. During the sleep period corresponding to the sleep time information, the terminal device remains in sleep mode and does not perform services, including skipping the execution of periodic TAU procedures or periodic registration procedures. In this method, the period during which the terminal device is not covered by the satellite network, as indicated by the terminal device's satellite coverage information, is not included in any eDRX cycle or TAU cycle and is a separate sleep period. Figure 3(c) is a schematic diagram of the sleep period. The sleep time information indicates a separate sleep period. The sleep period overlaps with the period during which the terminal device is not covered by the satellite network, or the sleep period is longer than the period during which the terminal device is not covered by the satellite network. During the sleep period, the terminal device enters a sleep state to ensure that it enters sleep mode during periods when it is not covered by the satellite network. This can avoid unnecessary and ineffective network connections and reduce the power consumption of the terminal device. See Figure 3(c). Time T1 is the sleep start time, and time T2 is the sleep end time. The time period between T1 and T2 overlaps with or is longer than the time period when the terminal device is not covered by the satellite network. Optionally, after the sleep period, an eDRX cycle is entered. The eDRX cycle may be determined based on an existing solution. The eDRX cycle also includes a sleep period, which is sometimes referred to as the eDRX sleep period. The sleep information determined in step 201 includes the sleep start time and sleep end time in the example in Figure 3(c).Alternatively, the sleep time information determined in step 201 includes the sleep start time and sleep duration in the example shown in Figure 3(c).

[0139] Step 202: The mobility management network element sends sleep time information to the terminal device. In response, the terminal device receives the sleep time information.

[0140] In the implementation, the mobility management network element may include sleep time information in the registration acceptance message sent to the terminal device. Optionally, the registration acceptance message may further include one or more of the following: eDRX cycles, periodic registration cycles, or periodic TAU cycles. Using a 4G network as an example, the sleep time information may be carried in the attach acceptance message or TAU acceptance message sent to the terminal device.

[0141] Step 203: The terminal device goes to sleep based on the sleep time information.

[0142] Specifically, the terminal device enters a sleep state during the sleep period corresponding to the sleep time information, and the sleep period includes the period during which the terminal device is not covered by the satellite network.

[0143] Step 204: When the deregistration timer (or detachment timer) corresponding to the terminal device expires, the mobility management network element determines, based on satellite coverage information, that the terminal device is not covered by the satellite network and decides to skip performing deregistration (or detachment) on the terminal device.

[0144] Step 204 is an optional step.

[0145] Skipping the deregistration process for a terminal device may also be understood as maintaining the terminal device's registration status without change. Skipping the detachment process for a terminal device may also be understood as maintaining the terminal device's attachment status without change.

[0146] In a 4G network, when the detach timer (or implicit detach timer) corresponding to a terminal device expires, if the Mobility Management Network element (MME) determines, based on satellite coverage information, that the terminal device is not covered by the satellite network, the Mobility Management Network element decides to skip detaching the terminal device, i.e., maintains the terminal device's current mobility management state as attached or EMM registered (EPS Mobility Management-Registered, EMM-Registered). If the Mobility Management Network element determines, based on satellite coverage information, that the terminal device is covered by the satellite network, the Mobility Management Network element decides to detach the terminal device, i.e., changes the terminal device's current mobility management state to detached or EMM unregistered. According to this solution, if the terminal device is not covered by the satellite network, the mobility management network element does not perform a detach procedure on the terminal device. This reduces the switching of the terminal device's status between attachment and detachment or registration and unregistration, thereby reducing signaling interaction between the terminal device and the network, and potentially lowering the terminal device's power consumption. This is because the terminal device consumes less power when it is not covered by the satellite network. If the mobility management network element detaches the terminal device, the terminal device then needs to be reattached after it is covered by the satellite network. As a result, more signaling interaction is triggered, and the terminal device's power consumption increases.

[0147] In a 5G network, when the deregistration timer (or implicit detach timer) corresponding to a terminal device expires, if the mobility management network element (AMF) determines, based on satellite coverage information, that the terminal device is not covered by the satellite network, the AMF decides to skip deregistration of the terminal device. If the AMF determines, based on satellite coverage information, that the terminal device is covered by the satellite network, the AMF decides to skip registration of the terminal device, i.e., keeps the terminal device in a registered state. According to this solution, since the mobility management network element does not deregister the terminal device when it is not covered by the satellite network, the switching of the terminal device's status between registered and deregistered is reduced, thereby reducing signaling interaction between the terminal device and the network, and potentially reducing the terminal device's power consumption. This is because the terminal device consumes less power when it is not covered by the satellite network. If a mobility management network element deregisters a terminal device, the terminal device must subsequently be re-registered after it is covered by the satellite network. This results in more signaling interactions and increased power consumption of the terminal device.

[0148] According to the solution described above, the mobility management network element determines sleep time information based on the satellite coverage information of the terminal device, and the sleep time period corresponding to the sleep time information includes the period during which the terminal device is not covered by the satellite network, in order to ensure that the terminal device can sleep as much as possible during the period during which it is not covered by the satellite network, thereby reducing the power consumption of the terminal device by avoiding unnecessary network connectivity operations such as cell scanning and cell selection.

[0149] Figure 4 is a schematic flowchart of a communication method according to an embodiment of the present application. The method may be used to solve the aforementioned problem 1. The method includes the following steps:

[0150] Step 401: When the deregistration timer (or detach timer) corresponding to the terminal device expires, the mobility management network element determines, based on the terminal device's satellite coverage information, that the terminal device is not covered by the satellite network.

[0151] For details on how to implement the determination of satellite coverage information for terminal devices using mobility management network elements, please refer to the explanation in step 201. Further details will not be provided again.

[0152] The deregistration timer may also be an implicit deregistration timer; this is not limited herein. The detach timer may also be an implicit detach timer; this is not limited herein.

[0153] Step 402: The mobility management network element decides to skip performing the deregistration (or detachment) of the terminal device.

[0154] Skipping the deregistration of a terminal device may also be understood as maintaining the terminal device's registration status without change. Skipping the detachment of a terminal device may also be understood as maintaining the terminal device's attachment status without change, i.e., keeping the terminal device always in an EMM-registered state. Optionally, if the terminal device is not deregistered, this responds if the terminal device is not covered by the satellite network.

[0155] In a 4G network, when the detach timer corresponding to a terminal device expires, if the Mobility Management Network element (MME) determines, based on satellite coverage information, that the terminal device is not covered by the satellite network, the MME decides to skip performing detachment on the terminal device, i.e., maintains the terminal device's current mobility management state as either attached or EMM registered. If the Mobility Management Network element determines, based on satellite coverage information, that the terminal device is covered by the satellite network, the MME decides to perform detachment on the terminal device, i.e., changes the terminal device's current mobility management state to either detached or EMM unregistered. According to this solution, if the terminal device is not covered by the satellite network, the Mobility Management Network element does not perform the detachment procedure on the terminal device, thus reducing the switching of the terminal device's status between attached and detached states. This reduces signaling interaction between the terminal device and the network, and may reduce the terminal device's power consumption. This is because terminal devices consume less power when they are not covered by the satellite network. When a mobility management network element detaches a terminal device, the terminal device must then be reattached after it is covered by the satellite network. As a result, more signaling interactions are triggered, increasing the terminal device's power consumption.

[0156] In a 5G network, when the deregistration timer for a terminal device expires, if the Mobility Management Network (AMF) determines, based on satellite coverage information, that the terminal device is not covered by the satellite network, the AMF decides to skip deregistration. If the AMF determines, based on satellite coverage information, that the terminal device is covered by the satellite network, the AMF decides to skip registration, meaning it maintains the terminal device in its registered state. According to this solution, since the AMF does not deregister the terminal device when it is not covered by the satellite network, the switching of the terminal device's status between registered and deregistered is reduced, thereby reducing signaling interaction between the terminal device and the network, and potentially reducing the terminal device's power consumption. This is because the terminal device consumes less power when it is not covered by the satellite network. If the AMF deregisters the terminal device, the terminal device needs to be re-registered after it is subsequently covered by the satellite network. As a result, more signaling interactions are triggered, increasing the power consumption of the terminal device.

[0157] According to the aforementioned solution, the switching of terminal device status between registration and unregistration or between attachment and detachment is reduced, which can reduce signaling interactions between the terminal device and the network, and thus reduce power consumption of the terminal device.

[0158] In the implementation method, after step 402, the following steps 403 and 404 may be carried out.

[0159] Step 403: The mobility management network element transmits the first information to the terminal device. In response, the terminal device receives the first information.

[0160] The first piece of information indicates that when a terminal device has an uplink transmission requirement, the terminal device will perform uplink transmission based on the satellite network coverage status.

[0161] Step 404: When there is an uplink transmission requirement, if the terminal device determines, based on the first information, that the terminal device is not covered by the satellite network, the terminal device decides to skip performing the uplink transmission.

[0162] The uplink transmission requirements herein include, but are not limited to, one or more of the following: periodic TAU, periodic registration, or uplink data transmission.

[0163] In the implementation method, the first piece of information is the satellite coverage information of the terminal device as described in step 401. The mobility management network element transmits the satellite coverage information of the terminal device to the terminal device, instructing the terminal device to perform uplink transmission based on the satellite coverage information when the terminal device has an uplink transmission requirement. Thus, when the terminal device has an uplink transmission requirement, it is determined based on the satellite coverage information whether the terminal device is currently covered by the satellite network. If the terminal device is not covered by the satellite network, it is decided to skip performing uplink transmission. If the terminal device is covered by the satellite network, it is decided to perform uplink transmission.

[0164] In an alternative implementation, the first piece of information is indication information, which clearly indicates that the terminal device will check the satellite network coverage status when it has an uplink transmission requirement and perform the uplink transmission based on the satellite network coverage status. Therefore, when the terminal device has an uplink transmission requirement, it first checks whether it is currently covered by the satellite network. If the terminal device is not covered by the satellite network, it is decided to skip performing the uplink transmission. If the terminal device is covered by the satellite network, it is decided to perform the uplink transmission.

[0165] In an alternative implementation, when the first information is transmitted to the terminal device in step 403, the mobility management network element further transmits satellite coverage information for the terminal device to the terminal device. In this case, the first information is, as specified herein, indication information, which clearly indicates that the terminal device will perform uplink transmission based on the satellite coverage information when it has an uplink transmission requirement. Therefore, if the terminal device has an uplink transmission requirement, the terminal device determines, based on the satellite coverage information, whether it is covered by the satellite network. If the terminal device is not covered by the satellite network, it is decided to skip performing uplink transmission. If the terminal device is covered by the satellite network, it is decided to perform uplink transmission.

[0166] According to the solutions in steps 403 and 404, when a terminal device is not covered by the satellite network, the terminal device will skip performing uplink transmission even if there is an uplink transmission requirement. This avoids unnecessary and ineffective network connectivity operations such as cell scanning and cell selection, thereby reducing the power consumption of the terminal device.

[0167] Figure 5 is a schematic flowchart of a communication method according to an embodiment of the present application. The method may be used to solve the aforementioned problem 2. The method includes the following steps:

[0168] Step 501: The mobility management network element determines the satellite coverage information for the terminal device.

[0169] In the implementation method, the mobility management network element may determine the satellite coverage information of the terminal device in accordance with the method described in step 201.

[0170] In an alternative implementation, the mobility management network element may determine the satellite coverage information of an end device using the following method: The mobility management network element sends a paging message to the access network device, which includes identification information for an idle end device and indicates that the end device should be paged. In this case, the access network device pages the end device. If the access network device determines that the cell in which the end device is located is not currently covered by the satellite network, the access network device fails to page. Therefore, the access network device sends a first message to the mobility management network element. The first message includes a paging failure indication and satellite coverage information for the satellite cell in which the end device is located. The paging failure indication indicates that the reason for this paging failure is that the end device is not covered by the satellite network. Optionally, the paging failure indication further indicates that the mobility management network element needs to perform reachability determination / paging based on the satellite coverage information. The satellite coverage information for the satellite cell where the terminal device is located is the satellite coverage information for the terminal device.

[0171] In an alternative implementation, the mobility management network element may determine the satellite coverage information of a terminal device using the following method: The mobility management network element sends a paging message to the access network device, which includes identification information for an idle terminal device and indicates that the terminal device should be paged. In this case, the access network device pages the terminal device. If the access network device determines that the cell in which the terminal device is located is not currently covered by the satellite network, the access network device fails to page. Therefore, the access network device sends a first message to the mobility management network element. The first message includes satellite coverage information for the satellite cell in which the terminal device is located. The satellite coverage information for the satellite cell in which the terminal device is located is the satellite coverage information for the terminal device. In addition, the satellite coverage information indicates that the reason for this paging failure is that the terminal device is not covered by the satellite network. Optionally, the satellite coverage information further indicates that mobility management network elements should perform reachability determination / paging based on the satellite coverage information.

[0172] In the implementation method, when the mobility management network element is a 5G AMF network element, the AMF network element may perform step 501 after receiving a downlink data arrival notification from the SMF network element; in other words, the downlink data arrival notification triggers the mobility management network element to perform step 501.

[0173] In the implementation method, when the mobility management network element is a 4G MME, the MME may perform step 501 after determining that user plane downlink data needs to be transmitted.

[0174] Step 502: The mobility management network element determines the maximum latency based on satellite coverage information, which indicates the maximum period of time it will wait until the terminal device becomes reachable.

[0175] The maximum latency specified herein is understood to cover the period of time when the terminal device is not covered by the satellite network, or when the terminal device should be covered by the satellite network after reaching the maximum latency. The maximum latency may be the downlink buffer period for 4G or the maximum latency period for 5G.

[0176] Optionally, prior to step 502, the mobility management network element may further determine, based on satellite coverage information, that the terminal device is unreachable.

[0177] In a 4G network, the Mobility Management Network element is the MME. After determining the maximum latency, the MME may determine the downlink data buffer expiration period based on the maximum latency to indicate whether data from the terminal device is currently buffered on the core network side. After the downlink data buffer expiration period expires, the MME determines that there is currently no downlink buffered data for the terminal device. In a 4G network, the maximum latency is sometimes referred to as the downlink data buffer time.

[0178] In a 5G network, the mobility management network element is the AMF network element. After determining the maximum latency, the AMF network element may transmit the maximum latency to the SMF network element. The SMF network element may then determine the extended buffer time based on the maximum latency. The extended buffer time indicates a specific period during which the user plane network element buffers downlink data. After the extended buffer time is reached and the buffered data has not yet been transmitted to the terminal device, the SMF discards the corresponding buffered data. In a 5G network, the maximum latency is sometimes also called the estimated maximum latency.

[0179] According to the aforementioned solution, the mobility management network element can determine reachability based on the satellite coverage information of the terminal device. If the terminal device is unreachable, the mobility management network element determines the maximum latency based on the satellite coverage information to ensure that the terminal device is not paged and that downlink data is not transmitted to the terminal device when it is not covered by the satellite network. This reduces power consumption of the mobility management network element and minimizes data loss.

[0180] In the implementation method, prior to steps 201, 401, and / or 501, the mobility management network element further determines that the terminal device's location is fixed or that the terminal device's movement trajectory is fixed. Alternatively, it is understood that the mobility management network element determines that the terminal device is a fixed-location terminal device or a terminal device with a fixed movement trajectory. For example, the mobility management network element may obtain the terminal device's subscription information and, based on the terminal device's subscription information, determine that the terminal device's location is fixed or that the terminal device's movement trajectory is fixed. In other words, the mobility management network element implements the solutions of the embodiments corresponding to Figures 2, 4, and / or 5 only for terminal devices with a fixed location or a fixed movement trajectory. A fixed movement trajectory may be understood as the terminal device having a specific mobility, but the terminal device's movement trajectory is predictable, and the network can sense the terminal device's geographical location.

[0181] The following describes the aforementioned solution with reference to specific examples. The following solution is applicable to future communication networks such as 4G, 5G, or 6G networks.

[0182] Figure 6 is a schematic flowchart of the communication method according to an embodiment of this application. This solution is a specific implementation of the embodiment corresponding to Figure 2.

[0183] The method includes the following steps:

[0184] Step 601: The access network device sends an N2 setup message to the mobility management network element. In response, the mobility management network element receives the N2 setup message.

[0185] After the access network device is powered on, an N2 setup message is sent in a procedure to establish an N2 interface between the access network device and the mobility management network element. If the current network is a 4G network, the N2 interface corresponds to the S1-MME interface of the 4G network.

[0186] Optionally, the N2 setup message includes the identification information of the satellite cell of the access network device, and the satellite ephemeris information or satellite coverage information corresponding to each satellite cell.

[0187] Step 602: The terminal device sends a registration request message to the access network device. In response, the access network device receives the registration request message.

[0188] The registration request message is used to request registration with the network.

[0189] The registration request message may be a registration request message in a 5G network, or an attach message or TAU request message in a 4G network.

[0190] Step 603: The access network device sends a registration request message and access network (AN) parameters to the mobility management network element. In response, the mobility management network element receives the registration request message and AN parameters. The registration request message is carried by the terminal device in a NAS message sent to the mobility management network element. The AN parameters are added by the access network device to the first N2 message and sent to the mobility management network element along with the registration request message.

[0191] If the N2 setup message in step 601 does not transmit the satellite cell identification information of the access network device and the ephemeris information or satellite coverage information corresponding to each satellite cell, the AN parameters added by the access network device in the subsequent registration procedure of the terminal device may include the ephemeris information or satellite coverage information corresponding to the satellite cell on which the terminal device is located.

[0192] Step 604: The mobility management network element determines that the terminal device's location or movement trajectory is fixed.

[0193] Alternatively, the mobility management network element is understood to determine whether a terminal device is a terminal device in a fixed location or a terminal device with a fixed movement trajectory.

[0194] In the implementation method, the mobility management network element may obtain subscription information for the terminal device and, based on that subscription information, determine whether the terminal device's location is fixed or whether the terminal device's movement trajectory is fixed.

[0195] Step 604 is an optional step.

[0196] Step 605: The mobility management network element determines the sleep start time of the terminal device and one or more of the periodic TAU cycle, periodic registration cycle, or eDRX cycle, based on ephemeris information or satellite coverage information corresponding to the satellite cell where the terminal device is located.

[0197] When a mobility management network element receives ephemeris information from an access network device that corresponds to the satellite cell where the terminal device is located, the mobility management network element determines the satellite coverage information corresponding to the satellite cell where the terminal device is located based on the ephemeris information corresponding to the satellite cell where the terminal device is located.

[0198] Periodic TAU corresponds to periodic registration procedures in 5G networks and periodic TAU procedures in 4G networks.

[0199] The satellite coverage information corresponding to the satellite cell where the terminal device is located is the satellite coverage information of the terminal device.

[0200] In the implementation, the period of time during which the terminal device is not covered by the satellite network, as indicated by the terminal device's satellite coverage information, is included in the periodic registration cycle, or the sleep period within the periodic registration cycle is understood to include the period of time during which the terminal device is not covered by the satellite network, as indicated by the terminal device's satellite coverage information. For a specific example of the implementation, please refer to Figure 3(a).

[0201] In the implementation, the period of time during which the terminal device is not covered by the satellite network, as indicated by the terminal device's satellite coverage information, is included in the eDRX cycle, or the sleep period within the eDRX cycle is understood to include the period of time during which the terminal device is not covered by the satellite network, as indicated by the terminal device's satellite coverage information. For a specific example of the implementation, please refer to Figure 3(b).

[0202] Step 606: Other steps in the registration procedure.

[0203] Step 607: The mobility management network element sends a non-access stratum (NAS) message to the terminal device. In response, the terminal device receives the NAS message.

[0204] The NAS message includes the sleep start time and further includes one or more of the following: a periodic TAU cycle, an eDRX cycle, or a periodic registration cycle.

[0205] In the implementation, the NAS message includes a registration acceptance message, an attach acceptance message, or a TAU acceptance message. The message includes a sleep start time and further includes one or more of the following: a periodic registration cycle, a periodic TAU cycle, or an eDRX cycle.

[0206] Step 608: The terminal device sleeps during a periodic TAU cycle, periodic registration cycle, or eDRX cycle, based on the sleep start time.

[0207] In this implementation, the terminal device enters a sleep state from a sleep start time during a periodic TAU cycle and exits the sleep state when the periodic TAU cycle ends. The sleep period of the terminal device includes the time when the terminal device is not covered by the satellite network. For example, the terminal device may sleep according to the method shown in Figure 3(a).

[0208] In the implementation, the terminal device enters a sleep state from the sleep start time during the eDRX cycle and exits the sleep state when the eDRX cycle ends. The sleep period of the terminal device includes the period during which the terminal device is not covered by the satellite network. For example, the terminal device may sleep according to the method shown in Figure 3(b).

[0209] According to the solution described above, in the terminal device registration process, the mobility management network element determines the sleep start time and one or more of the eDRX cycle, periodic TAU cycle, or periodic registration cycle based on ephemeris information or satellite coverage information provided by the access network device corresponding to the cell, ensuring that the terminal device can sleep as much as possible during periods when it is not covered by the satellite network, avoiding unnecessary network connectivity operations such as cell scanning and cell selection, thereby reducing the terminal device's power consumption.

[0210] Figure 7 is a schematic flowchart of a communication method according to an embodiment of this application. This solution is a specific implementation of the embodiment corresponding to Figure 2. The method includes the following steps:

[0211] Steps 701 through 704 are the same as steps 601 through 604.

[0212] Step 704 is an optional step.

[0213] Step 705: The mobility management network element determines the sleep time information for the terminal device based on ephemeris information or satellite coverage information corresponding to the satellite cell where the terminal device is located.

[0214] When a mobility management network element receives ephemeris information from an access network device corresponding to the satellite cell where the terminal device is located, the mobility management network element determines the satellite coverage information corresponding to the satellite cell where the terminal device is located based on the ephemeris information. The satellite coverage information corresponding to the satellite cell where the terminal device is located is the satellite coverage information of the terminal device.

[0215] In the implementation, sleep time information includes the sleep start time and sleep end time, and the sleep period between the sleep start time and sleep end time is the period during which the terminal device is not covered by the satellite network.

[0216] In the implementation, the sleep time information includes the sleep start time and sleep end time, and the sleep period between the sleep start time and sleep end time includes the period during which the terminal device is not covered by the satellite network. In other words, the sleep period indicated by the sleep start time and sleep end time is longer than the period during which the terminal device is not covered by the satellite network.

[0217] In an alternative implementation, sleep time information may include the sleep start time and sleep duration, and the sleep end time may be obtained based on the sleep start time and sleep duration.

[0218] During the sleep period corresponding to the sleep time information, the terminal device will remain in sleep mode and will not perform any services, even if periodic TAU, periodic registration, or transmission of uplink data that should be transmitted does not occur.

[0219] Optionally, a mobility management network element may determine, based on service information and in accordance with existing methods, one or more of the following: an eDRX cycle, a periodic TAU cycle, or a periodic registration cycle, during the time period in which a terminal device is covered by the satellite network.

[0220] In the implementation, periods of time during which the terminal device is not covered by the satellite network, as indicated by the terminal device's satellite coverage information, are not included in any eDRX cycle, periodic TAU cycle, or periodic registration cycle, and are separate sleep periods.

[0221] Step 706: Other steps in the registration procedure.

[0222] Step 707: The mobility management network element sends a NAS message to the terminal device. In response, the terminal device receives the NAS message.

[0223] NAS messages include sleep time information. Optionally, NAS messages may further include one or more of the following: eDRX cycles, periodic TAU cycles, or periodic registration cycles.

[0224] In the implementation, NAS messages include a registration acceptance message, an attach acceptance message, or a TAU acceptance message. The message includes sleep time information. Optionally, a registration acceptance message may further include one or more of the following: an eDRX cycle, a periodic TAU cycle, or a periodic registration cycle.

[0225] Step 708: The terminal device goes to sleep based on the sleep time information.

[0226] The terminal device will sleep during the sleep time period indicated by the sleep time information, and no services will be performed, even if periodic TAU, periodic registration, or transmission of uplink data that should be transmitted does not occur.

[0227] Optionally, after a sleep period indicated by the sleep time information, the terminal device enters satellite network coverage. In this case, the terminal device may sleep based on the eDRX cycle, the periodic TAU cycle, or the periodic registration cycle.

[0228] Step 709: When the deregistration timer (or detach timer) corresponding to the terminal device expires, the mobility management network element decides whether to deregister (or detach) the terminal device based on the terminal device's sleep time information.

[0229] After the mobility management network element determines that the deregistration timer (or detachment timer) corresponding to the terminal device has expired, the mobility management network element determines, based on the terminal device's sleep time information, whether the terminal device is currently in a sleep time period corresponding to when the terminal device is not covered by the satellite network. If the terminal device is currently in a sleep time period corresponding to when the terminal device is not covered by the satellite network, the mobility management network element decides to skip performing deregistration (or detachment) on the terminal device. If the terminal device is not currently in a sleep time period corresponding to when the terminal device is not covered by the satellite network, the mobility management network element decides to perform deregistration (or detachment) on the terminal device.

[0230] Step 709 is an optional step.

[0231] In the above-described embodiment, during the terminal device registration process, the mobility management network element determines sleep time information based on ephemeris information or satellite coverage information provided by the access network device corresponding to the satellite cell, thereby ensuring that the terminal device sleeps as much as possible during periods when it is not covered by the satellite network, avoiding unnecessary network connection operations such as cell selection, and reducing the power consumption of the terminal device.

[0232] In terms of implementation methods, the embodiment corresponding to Figure 7 can be applied to scenarios where the terminal device is not covered by the satellite network for extended periods. A new power-saving mode is introduced. In other words, during periods when the terminal device is not covered by the satellite network, the terminal device remains in sleep mode and does not perform any services, including skipping periodic TAU, periodic registration, or uplink data transmission. This avoids unnecessary and ineffective network connectivity operations such as cell scanning and cell selection, and minimizes power consumption of the terminal device.

[0233] Figure 8 is a schematic flowchart of the communication method according to an embodiment of this application. This solution is a specific implementation of the embodiment corresponding to Figure 4.

[0234] The method includes the following steps:

[0235] Steps 801 through 804 are the same as steps 601 through 604.

[0236] Step 804 is an optional step.

[0237] Step 805: The mobility management network element determines the satellite coverage information of the terminal device.

[0238] When a mobility management network element receives ephemeris information from an access network device corresponding to the satellite cell where the terminal device is located, the mobility management network element determines the satellite coverage information corresponding to the satellite cell where the terminal device is located based on the ephemeris information. The satellite coverage information corresponding to the satellite cell where the terminal device is located is the satellite coverage information of the terminal device.

[0239] When a mobility management network element receives satellite coverage information from an access network device corresponding to the satellite cell where the terminal device is located, the satellite coverage information corresponding to the satellite cell where the terminal device is located is the satellite coverage information of the terminal device.

[0240] Optionally, a mobility management network element may determine an eDRX cycle, a periodic TAU cycle, or a periodic registration cycle according to existing methods.

[0241] Step 806: Other steps in the registration procedure.

[0242] Step 807: The mobility management network element sends a NAS message to the terminal device. In response, the terminal device receives the NAS message.

[0243] The NAS message includes indication information and satellite coverage information for the terminal device. Optionally, the NAS message further includes one or more of the following: eDRX cycles, periodic TAU cycles, or periodic registration cycles. The indication information tells the terminal device to initiate a periodic TAU procedure, periodic registration procedure, or uplink data transmission based on the terminal device's satellite coverage information when the periodic TAU timer or periodic registration timer expires, or when there is uplink data transmission.

[0244] In the implementation, the NAS message includes a registration acceptance message, an attach acceptance message, or a TAU acceptance message. The message includes indication information and satellite coverage information for the terminal device. Optionally, the message further includes one or more of the following: an eDRX cycle, a periodic TAU cycle, or a periodic registration cycle.

[0245] Step 808: The terminal device decides whether to initiate a periodic TAU, periodic registration, or uplink data transmission based on the indication information and the terminal device's satellite coverage information.

[0246] Specifically, based on indication information and the satellite coverage information of the terminal device, it is determined whether the terminal device is covered by the satellite network, i.e., whether the terminal device is currently covered by the satellite network. When the terminal device is covered by the satellite network, the terminal device initiates periodic TAU, periodic registration, or uplink data transmission. When the terminal device is not covered by the satellite network, the terminal device does not initiate periodic TAU, periodic registration, or uplink data transmission.

[0247] Step 809: The mobility management network element determines whether to deregister (or detach) the terminal device based on the terminal device's indication information and satellite coverage information.

[0248] Specifically, when the deregistration timer (or detachment timer) corresponding to a terminal device expires, a decision is made based on the terminal device's satellite coverage information whether or not to deregister (or detach) the terminal device. If the terminal device is covered by the satellite network, the mobility management network element performs the deregistration (or detachment) of the terminal device. If the terminal device is not covered by the satellite network, the mobility management network element skips performing the deregistration (or detachment) of the terminal device.

[0249] In the embodiments described above, during terminal device registration, attachment, or TAU processing, the mobility management network element determines the satellite coverage information of the terminal device and indicates to the terminal device that it will perform periodic TAU, periodic registration, or uplink data transmission based on the satellite coverage information. This prevents the terminal device from performing periodic TAU, periodic registration, or uplink data transmission during time periods when the terminal device is not covered by the satellite network, thereby avoiding unnecessary network connection operations such as cell scanning and cell selection, and reducing the power consumption of the terminal device. In addition, it is also possible to avoid the terminal device being unregistered (or detached) by the network when the terminal device is in a time period when it is not covered by the satellite network.

[0250] In terms of implementation methods, the embodiment corresponding to Figure 8 can be applied to scenarios where the terminal device is not covered by the satellite network for extended periods. This is because there is a limit to the cycle time of periodic TAU or periodic registration, and it may not be very large. Therefore, when the terminal device is not covered by the satellite network for a long period, it is necessary to perform periodic TAU or periodic registration. In this case, power consumption losses are significant because the terminal device is not covered by the satellite network and continuously performs cell scanning and cell selection. In addition, since the network does not receive periodic TAU or periodic registration from the terminal device, the terminal device is unregistered or detached. Therefore, in order to avoid unnecessary periodic TAU or periodic registration when an idle terminal device is not covered by the satellite network, in the embodiment corresponding to Figure 8, when the terminal device is not covered by the satellite network, the terminal device does not perform periodic TAU or periodic registration and uplink data transmission, and the mobility management network element on the network side does not perform unregistration (or detachment) to the terminal device. Thus, signaling interaction between the terminal device and the mobility management network element can be reduced to the greatest extent possible, and power consumption of the terminal device is reduced.

[0251] Figure 9 is a schematic flowchart of the communication method according to an embodiment of this application. This solution is a specific implementation of the embodiment corresponding to Figure 4.

[0252] The method includes the following steps:

[0253] Steps 901 through 906 are the same as steps 801 through 806.

[0254] Step 907: The mobility management network element sends a NAS message to the terminal device. In response, the terminal device receives the NAS message.

[0255] NAS messages include indication information. Optionally, NAS messages may further include one or more of the following: eDRX cycles, periodic TAU cycles, or periodic registration cycles. The indication information tells the terminal device whether it can detect when a periodic TAU timer or periodic registration timer has expired, or when there is uplink data transmission, whether the terminal device is covered by the satellite network.

[0256] In the implementation, the NAS message includes a registration acceptance message, an attach acceptance message, or a TAU acceptance message. The message includes indication information. Optionally, the registration acceptance message further includes an eDRX cycle and / or a TAU cycle.

[0257] Step 908: The terminal device decides whether to initiate periodic TAU, periodic registration, or uplink data transmission based on the indication information.

[0258] Specifically, based on the indication information, it is determined whether the terminal device is covered by the satellite network, that is, whether the terminal device is currently covered by the satellite network. If the terminal device is covered by the satellite network, the terminal device initiates periodic TAU, periodic registration, or uplink data transmission. If the terminal device is not covered by the satellite network, the terminal device does not initiate periodic TAU, periodic registration, or uplink data transmission.

[0259] Step 909 is the same as step 809.

[0260] In the embodiments described above, during the terminal device registration process, the mobility management network element indicates to the terminal device whether it is covered by the satellite network, and whether it performs periodic TAU, periodic registration, or uplink data transmission. This prevents the terminal device from performing periodic TAU, periodic registration, or uplink data transmission during time periods when it is not covered by the satellite network, thereby avoiding unnecessary network connection operations such as cell scanning and cell selection, and reducing the power consumption of the terminal device. In addition, it is also possible to avoid the terminal device being unregistered (or detached) by the network when it is in a time period when it is not covered by the satellite network.

[0261] In terms of implementation methods, the embodiment corresponding to Figure 9 can be applied to scenarios where a terminal device is not covered by the satellite network for an extended period. This is because there is a limit to the cycle time of periodic TAU or periodic registration, and it may not be very large. Therefore, when a terminal device is not covered by the satellite network for a long period, it is necessary to perform periodic TAU or periodic registration. In this case, power consumption losses are significant because the terminal device is not covered by the satellite network and continuously performs network connectivity operations such as cell scanning and cell selection. In addition, since the network does not receive periodic TAU requests or periodic registration requests from the terminal device, the terminal device is unregistered or detached. Therefore, in order to avoid unnecessary periodic TAU or periodic registration when an idle terminal device is not covered by the satellite network, in the embodiment corresponding to Figure 9, when the terminal device is not covered by the satellite network, the terminal device does not perform periodic TAU or periodic registration and uplink data transmission, and the mobility management network element on the network side does not perform unregistration (or detachment) to the terminal device. As a result, signaling interaction between the terminal device and the mobility management network element can be reduced to the greatest extent possible, and power consumption of the terminal device is reduced.

[0262] Figure 10 is a schematic flowchart of the communication method according to an embodiment of this application. This solution is a specific implementation of the embodiment corresponding to Figure 5.

[0263] The method includes the following steps:

[0264] Step 1001 is the same as step 601.

[0265] Step 1002: After the terminal device enters an idle state, the access network device sends an N2 message to the mobility management network element. In response, the mobility management network element receives the N2 message.

[0266] If the N2 setup message in step 1001 does not carry the satellite cell identification information of the access network device and the ephemeris information or satellite coverage information corresponding to each satellite cell, the N2 message may include the ephemeris information or satellite coverage information corresponding to the satellite cell where the terminal device is located. Optionally, the N2 message may further include the identification information of the satellite cell where the terminal device is located. The satellite cell where the terminal device is located may be understood as the satellite cell last accessed by the terminal device before the terminal device entered an idle state. Specifically, the N2 message may be an N2 release message, corresponding to the S1 release message in a 4G network.

[0267] Step 1003 is the same as step 604.

[0268] Step 1003 is an optional step.

[0269] Step 1004: The mobility management network element determines whether the terminal device is reachable.

[0270] In the implementation, the mobility management network element determines whether a terminal device is reachable based on the terminal device's satellite coverage information. If the terminal device is not currently covered by the satellite network, the terminal device is unreachable. If the terminal device is currently covered by the satellite network, whether the terminal device is reachable is determined based on existing solutions, for example, based on the terminal device's power-saving sleep state. The terminal device's satellite coverage information is the satellite coverage information of the satellite cell in which the terminal device is located.

[0271] In the implementation, the mobility management network element determines whether a terminal device is reachable based on the terminal device's satellite coverage information and the eDRX cycle, periodic TAU cycle, or periodic registration cycle. A terminal device is unreachable if it is not currently covered by the satellite network, or if it is in a sleep phase of the eDRX cycle, or a sleep phase of the periodic TAU cycle, or a sleep phase of the periodic registration cycle. A terminal device is reachable if it is currently covered by the satellite network, is not in a sleep phase of the eDRX cycle, is not in a sleep phase of the periodic TAU cycle, or is not in a sleep phase of the periodic registration cycle. Please understand that the sleep time for a periodic TAU cycle or periodic registration cycle is the sleep period during which the terminal device enters a sleep state after a period of time has passed since the terminal device transitioned from a connected state to an idle state, for example, from a 4G network power saving mode (PSM) or a 5G network uplink-only connection (MICO) mode.

[0272] Step 1005: If the terminal device is unreachable, the mobility management network element determines the maximum latency based on the terminal device's satellite coverage information.

[0273] For specific implementations of this step, please refer to the explanation in step 502.

[0274] Step 1006: When the terminal device enters a reachable state, the mobility management network element sends a paging message to the access network device. In response, the access network device receives the paging message.

[0275] The paging message includes the identification information of the terminal device and the identification information of the paging cell.

[0276] A paging cell may be the last cell accessed by the terminal device, or it may be all cells within the tracking area where the last cell accessed by the terminal device is located.

[0277] Step 1007: The access network device pages the terminal devices.

[0278] According to the aforementioned solution, the mobility management network element can determine reachability based on the satellite coverage information of the terminal device. If the terminal device is unreachable, the mobility management network element determines the maximum latency based on the satellite coverage information to ensure that the terminal device is not paged and that downlink data is not transmitted to the terminal device when it is not covered by the satellite network. This reduces power consumption of the mobility management network element and minimizes data loss.

[0279] In the implementation method, if the mobility management network element of this solution is a 4G MME, before step 1004, the MME may further receive a downlink data arrival notification from the user plane network element, which triggers the MME to perform step 1004. In addition, after step 1005, the MME further determines the downlink data buffer expiration period based on the maximum latency or downlink buffer time to indicate whether the terminal device's data is currently buffered on the core network side. After the downlink data buffer expiration period has expired, the MME determines that there is currently no downlink buffered data for the terminal device.

[0280] In the implementation method, when the mobility management network element of this solution is a 5G AMF network element, before step 1004, the AMF network element may further receive a downlink data arrival notification from the SMF network element, and the downlink data arrival notification triggers the AMF network element to perform step 1004. In addition, after step 1005, the AMF network element further indicates to the SMF network element and / or the user plane network element to buffer data based on the maximum waiting time. Next, the SMF network element may determine an extended buffer time based on the maximum waiting time. The extended buffer time indicates a specific period during which the user plane network element buffers downlink data. After the extended buffer time is reached and the buffered data has not yet been transmitted to the terminal device, the SMF network element discards the corresponding buffered data.

[0281] FIG. 11 is a schematic flowchart of a communication method according to an embodiment of the present application. This solution is a specific implementation of the embodiment corresponding to FIG. 5.

[0282] The method includes the following steps.

[0283] Step 1101: The mobility management network element sends a paging message to the access network device. Correspondingly, the access network device receives the paging message.

[0284] The paging message includes the identification information of the terminal device and the identification information of the paging cell.

[0285] The paging cell may be the cell last accessed by the terminal device, or may be all cells within the tracking area where the cell last accessed by the terminal device is located.

[0286] Step 1102: The access network device determines that the satellite cell where the terminal device is located is not covered by the satellite network.

[0287] In the implementation, the access network device determines whether the terminal device is covered by the satellite network based on the terminal device's satellite coverage information. If the terminal device is not currently covered by the satellite network, paging fails. If the terminal device is currently covered by the satellite network, the terminal device is paged. The terminal device's satellite coverage information is the satellite coverage information of the satellite cell where the terminal device is located.

[0288] Step 1103: The access network device sends the first message to the mobility management network element. In response, the mobility management network element receives the first message.

[0289] Specifically, the first message could be an N2 message or a paging failure message.

[0290] The access network device determines that the terminal device is not currently covered by the satellite network. Therefore, the access network device sends a first message to the mobility management network element. The first message includes a paging failure indication and satellite coverage information for the terminal device. The paging failure indication indicates that the reason for this paging failure is that the terminal device is not covered by the satellite network. Optionally, the paging failure indication further indicates that the mobility management network element needs to perform reachability determination / paging based on the satellite coverage information.

[0291] In an alternative implementation, the access network device determines that the terminal device is not currently covered by the satellite network. Therefore, the access network device sends a first message to the mobility management network element. This first message includes satellite coverage information for the terminal device. The satellite coverage information indicates that the reason for this paging failure is that the terminal device is not covered by the satellite network. Optionally, the satellite coverage information further indicates that the mobility management network element should perform reachability determination / paging based on the satellite coverage information.

[0292] Step 1104: The mobility management network element determines the maximum latency based on the satellite coverage information of the terminal device.

[0293] For specific implementations of this step, please refer to the explanation in step 502.

[0294] Steps 1105 and 1106 are the same as steps 1006 and 1007.

[0295] According to the solution described above, when a mobility management network element notifies an access network device to page a terminal device, the access network device determines whether the terminal device is currently eligible to be paged, based on the terminal device's satellite coverage information. If the terminal device is not within satellite network coverage, the access network device notifies the mobility management network element that paging failed and sends the terminal device's satellite coverage information to the mobility management network element, which then determines a maximum latency based on that satellite coverage information to ensure that the terminal device is not paged when it is not covered by the satellite network. This reduces unnecessary signaling interactions between the mobility management network element and the access network device, avoiding wasted paging resources on the access network device and loss of downlink data from the terminal device.

[0296] In the implementation method, if the mobility management network element of this solution is a 4G MME, before step 1101, the MME may further receive a downlink data arrival notification from the user plane network element, which triggers the MME to perform step 1101. In addition, after step 1104, the MME further determines the downlink data buffer expiration period based on the maximum latency, i.e., the downlink buffer time, to indicate whether the terminal device's data is currently buffered on the core network side. After the downlink data buffer expiration period has expired, the MME determines that there is currently no downlink buffered data for the terminal device.

[0297] In the implementation method, if the mobility management network element of this solution is a 5G AMF network element, before step 1101, the AMF network element may further receive a downlink data arrival notification from the SMF network element, which triggers the AMF network element to perform step 1101. In addition, after step 1104, the AMF network element further indicates the SMF network element and / or user plane network element to buffer the data based on the maximum latency. The SMF network element may then determine an extended buffer time based on the maximum latency. The extended buffer time indicates a specific period during which the user plane network element buffers the downlink data. After the extended buffer time has been reached and the buffered data has not yet been sent to the terminal device, the SMF network element discards the corresponding buffered data.

[0298] In the embodiments corresponding to Figure 12 and Figure 14, an example is used in the description in which a mobility management network element determines an appropriate periodic TAU cycle or periodic registration cycle, thereby causing the terminal device to skip performing uplink signaling or uplink data transmission during periods when the terminal device is not covered by the satellite network, based on the periodic TAU cycle or periodic registration cycle. In actual application, the mobility management network element may determine another parameter (e.g., service gap or eDRX), thereby causing the terminal device to skip performing uplink signaling or uplink data transmission during periods when the terminal device is not covered by the satellite network, based on that other parameter. It should be understood that “periodic TAU cycle” and “periodic registration cycle” in the embodiments corresponding to Figure 12 and Figure 14 may be replaced with another parameter (such as service gap or eDRX). For the definition of service gap, see TS23.401 V17.2.0. The “other parameter” may be a parameter indicating a period.

[0299] Figure 12 is a schematic flowchart of a communication method according to an embodiment of this application. For example, in a 4G application scenario, the mobility management network element and the access network device may be an MME and an eNB, respectively. For example, in a 5G application scenario, the mobility management network element and the access network device may be an AMF and a gNB, respectively. The terminal device in this embodiment is a satellite access type terminal device.

[0300] The method includes the following steps:

[0301] Step 1201: The mobility management network element determines a periodic TAU cycle or periodic registration cycle based on the satellite coverage information of the terminal device.

[0302] Optionally, the position of the terminal device is fixed, or the movement trajectory of the terminal device is fixed.

[0303] For the meaning of satellite coverage information, please refer to the above description. Details will not be described again in this specification.

[0304] Optionally, when determining that the terminal device is a satellite access type terminal device, the mobility management network element may determine a periodic TAU cycle or a periodic registration cycle based on the satellite coverage information of the terminal device.

[0305] In 4G, the mobility management network element is the MME, and the MME determines the periodic TAU cycle. In a specific implementation, the periodic TAU cycle may be represented by a periodic TAU timer. In 5G, the mobility management network element is the AMF, and the AMF determines the periodic registration cycle. In a specific implementation, the periodic registration cycle may be represented by a periodic registration timer.

[0306] When the terminal device is not covered by the satellite network, to skip the terminal device from performing the periodic TAU procedure or the periodic registration procedure, and to ensure that the terminal device remains in the sleep state, that is, to ensure that the time period from when the terminal device enters the idle state until before the periodic TAU timer or the periodic registration timer expires includes the time period when the terminal device is not covered by the satellite network, the time period corresponding to the periodic TAU cycle includes the time period when the terminal device is not covered by the satellite network, or the time period corresponding to the periodic registration cycle includes the time period when the terminal device is not covered by the satellite network.

[0307] The following describes different implementation methods for triggering the mobility management network element to perform step 1201.

[0308] Method 1: The mobility management network element determines, based on the terminal device's satellite coverage information, that the terminal device is about to lose satellite network coverage and sends indication information to the access network device. The indication information tells the access network device to perform the terminal device connection release procedure. The access network device then sends a UE context release request to the mobility management network element. The UE context release request is used to request the mobility management network element to release the context of the terminal device. After receiving the UE context release request, the mobility management network element is triggered to perform step 1201.

[0309] Method 2: Based on the terminal device's satellite coverage information, the access network device determines that the terminal device is about to lose satellite network coverage and triggers the access network device to send a context release request to the mobility management network element. The context release request is used to request the mobility management network element to release the context of the terminal device. After receiving the UE context release request, the mobility management network element is triggered to perform step 1201.

[0310] Method 3: Based on the terminal device's satellite coverage information, the terminal device determines that it is about to lose satellite network coverage and sends a TAU request or mobility registration update request to the mobility management network element. After receiving the TAU request or mobility registration update request, the mobility management network element is triggered to perform step 1201.

[0311] Optionally, the mobility management network element further determines a first period based on the terminal device's satellite coverage information. The first period is the time from when the terminal device enters an idle state until when the terminal device enters a sleep state. The first period is also sometimes called the period when the terminal device is active (active time). When the terminal device is active, the network may call the terminal device from an idle state to a connected state by paging.

[0312] Step 1202: The mobility management network element sends a periodic TAU cycle or periodic registration cycle to the terminal device.

[0313] In 4G, a mobility management network element, such as an MME, sends a periodic TAU cycle to the terminal device. Optionally, the MME sends a GUTI Reallocation Command to the terminal device, which carries the periodic TAU cycle. Alternatively, the MME sends a TAU acceptance message to the terminal device, which carries the periodic TAU cycle.

[0314] In 5G, mobility management network elements, such as AMF, send periodic registration cycles to terminal devices. Optionally, AMF sends UE Configuration Update Commands to terminal devices, which carry the periodic registration cycles. Alternatively, AMF sends mobility registration update acceptance messages to terminal devices, which also carry the periodic registration cycles.

[0315] In the implementation, the mobility management network element transmits a periodic TAU cycle or periodic registration cycle to the terminal device using an access network device. In other words, the mobility management network element transmits a periodic TAU cycle or periodic registration cycle to the access network device, which then transmits a periodic TAU cycle or periodic registration cycle to the terminal device.

[0316] Optionally, the mobility management network element may further transmit a first period to the terminal device. The first period is the period from when the terminal device enters an idle state until when the terminal device enters a sleep state. The first period is also sometimes called the period when the terminal device is active (active time). When the terminal device is active, the network may call the terminal device from an idle state to a connected state by paging.

[0317] Optionally, the mobility management network element may further transmit a cause value to the terminal device, where the cause value is discontinuous satellite coverage, or where the cause value indicates that the terminal device will skip performing uplink transmission while in sleep mode.

[0318] Step 1203: The terminal device performs periodic TAU based on a periodic TAU cycle, or performs periodic registration based on a periodic registration cycle.

[0319] Figure 13(a) is a schematic diagram of a periodic TAU cycle or periodic registration cycle according to an embodiment of the present application. The start time of the periodic TAU cycle (i.e., periodic TAU timer) or periodic registration cycle (i.e., periodic registration timer) may be when the terminal device enters an idle state. The time period corresponding to the periodic TAU cycle or the time period corresponding to the periodic registration cycle includes a time period during which the terminal device is not covered by the satellite network. The terminal device enters a sleep state during the time period during which the terminal device is not covered by the satellite network.

[0320] Figure 13(b) is another schematic diagram of a periodic TAU cycle or periodic registration cycle according to an embodiment of the present application. The start time of the periodic TAU cycle (i.e., periodic TAU timer) or periodic registration cycle (i.e., periodic registration timer) may be when the terminal device enters an idle state. The time period corresponding to the periodic TAU cycle, or the time period corresponding to the periodic registration cycle, includes a time period during which the terminal device is not covered by the satellite network. The time period corresponding to the periodic TAU cycle, or the time period corresponding to the periodic registration cycle, further includes a first period during which the terminal device may be woken up by the network side via paging and enter connected mode. The terminal device enters a sleep state during the time period during which the terminal device is not covered by the satellite network.

[0321] Optionally, if a terminal device receives a cause value that indicates it should skip performing uplink transmissions while in sleep mode, then, when an uplink transmission requirement exists, the terminal device will skip performing uplink transmissions based on the cause value during the time period corresponding to a periodic TAU cycle or periodic registration cycle.

[0322] According to the aforementioned solution, the mobility management network element determines the periodic TAU cycle or periodic registration cycle based on the satellite coverage information of the terminal device, such that the period corresponding to the periodic TAU cycle or periodic registration cycle includes a period during which the terminal device is not covered by the satellite network. This ensures that the terminal device avoids performing the periodic TAU procedure or periodic registration procedure during periods when it is not covered by the satellite network, thereby avoiding unnecessary network connectivity operations such as cell selection and reducing the power consumption of the terminal device.

[0323] Figure 14 is a schematic flowchart of a communication method according to an embodiment of the present application. This solution is a specific implementation of the embodiment corresponding to Figure 12. For example, in a 4G application scenario, the mobility management network element and the access network device may be an MME and an eNB, respectively. For example, in a 5G application scenario, the mobility management network element and the access network device may be an AMF and a gNB, respectively. The terminal device in this embodiment is a satellite access type terminal device.

[0324] The method includes the following steps:

[0325] Step 1401: The mobility management network element determines, based on the terminal device's satellite coverage information, that the terminal device is about to go out of satellite network coverage and sends indication information to the access network device. The access network device receives the indication information in response.

[0326] Optionally, the terminal device's position can be fixed, or the terminal device's movement trajectory can be fixed.

[0327] In one implementation, the mobility management network element may receive satellite coverage information for terminal devices from an access network device, a third party, or the terminal device itself. In another implementation, the mobility management network element may receive cell ephemeris information from an access network device, a third party, or the terminal device, and then determine the satellite coverage information for the terminal device based on that cell ephemeris information.

[0328] The indication information tells the access network device to perform a procedure to release the terminal device. In 4G, the procedure to release the terminal device is the S1 release procedure. In 5G, the procedure to release the terminal device is the procedure to release the access network (AN).

[0329] Step 1401 is an optional step.

[0330] Step 1402: The access network device sends a UE context release request to the mobility management network element. In response, the mobility management network element receives the UE context release request.

[0331] A UE context release request is used to request a mobility management network element to release the UE context so that the mobility management network element can release its connection to the terminal device, allowing the terminal device to enter an idle state.

[0332] In the implementation method, when step 1401 is performed, the indication information triggers the access network device to perform step 1402.

[0333] In an alternative implementation, if step 1401 is not performed, the access network device may determine, based on the terminal device's satellite coverage information, that the terminal device is likely to lose satellite network coverage, and then trigger the access network device to perform step 1402.

[0334] In alternative implementations, if step 1401 is not performed, the access network device may trigger the access network device to perform step 1402 for other reasons. Other reasons as defined herein include, but are not limited to, the service not being performed on the terminal device, operator operation and maintenance system intervention (O&M intervention), or unspecified failure.

[0335] Optionally, in 4G, after receiving a UE context release request, the mobility management network element (i.e., MME) may further request the serving gateway (S-GW) to release the bearer resources. Optionally, in 5G, after receiving a UE context release request, the mobility management network element (i.e., AMF) may further request the SMF to release the bearer resources.

[0336] Step 1403: The mobility management network element determines a periodic TAU cycle or periodic registration cycle based on the satellite coverage information of the terminal device.

[0337] Optionally, when determining that a terminal device is a satellite access type terminal device, the mobility management network element may determine a periodic TAU cycle or a periodic registration cycle based on the terminal device's satellite coverage information.

[0338] In 4G, the mobility management network element is the MME, which determines the periodic TAU cycle. In certain implementations, the periodic TAU cycle may be represented by a periodic TAU timer. In 5G, the mobility management network element is the AMF, which determines the periodic registration cycle. In certain implementations, the periodic registration cycle may be represented by a periodic registration timer.

[0339] To ensure that a terminal device skips performing a periodic TAU procedure or periodic registration procedure when it is not covered by the satellite network, and that the terminal device remains in a sleep state, in other words, to ensure that the time period from when the terminal device enters an idle state until before the periodic TAU timer or periodic registration timer expires includes the time period when the terminal device is not covered by the satellite network, the time period corresponding to a periodic TAU cycle includes the time period when the terminal device is not covered by the satellite network, or the time period corresponding to a periodic registration cycle includes the time period when the terminal device is not covered by the satellite network.

[0340] Optionally, the mobility management network element further determines a first period. The first period is the time from when the terminal device enters an idle state until when the terminal device enters a sleep state. The first period is also sometimes called the period when the terminal device is active (active time). When the terminal device is active, the network may call the terminal device from an idle state to an active state by paging.

[0341] Step 1404: The mobility management network element sends a reassignment command to the terminal device, which includes a periodic TAU cycle or a periodic registration cycle. The terminal device receives the reassignment command accordingly.

[0342] Optionally, the reassignment command may further include the period during which the terminal device is active.

[0343] Optionally, the reassignment command may further include a cause value, which is discontinuous satellite coverage. Optionally, the cause value may further indicate that the terminal device skips performing uplink transmission while in sleep mode. Uplink transmission as used herein includes uplink service data transmission and / or uplink signaling transmission.

[0344] Step 1405: The terminal device sends a reassignment response to the mobility management network element. In response, the mobility management network element receives the reassignment response.

[0345] In 4G, the reassignment command may be a GUTI reassignment command. The GUTI reassignment command includes a periodic TAU cycle and optionally further includes a first period and / or cause value. The reassignment response may be a GUTI reassignment complete message.

[0346] In 4G, the reassignment command may be a UE configuration update command, which includes a periodic registration cycle and optionally further includes a first period and / or cause value. The reassignment response may be a UE configuration update complete message.

[0347] Steps 1404 and 1405 are optional steps.

[0348] Step 1406: The mobility management network element sends a UE context release command to the access network device. In response, the access network device receives the UE context release command.

[0349] The UE context release command indicates to the access network device that it is releasing the UE context.

[0350] If steps 1404 and 1405 are not performed, the UE context release command includes a periodic TAU cycle or a periodic registration cycle, and optionally further includes a first period and / or cause value.

[0351] Step 1407: The access network device sends an RRC connection release request to the terminal device. In response, the terminal device receives the RRC connection release request.

[0352] If the UE context release command includes a periodic TAU cycle or a periodic registration cycle, the RRC connection release request includes a periodic TAU cycle or a periodic registration cycle. If the UE context release command further includes a first period and / or cause value, the RRC connection release request further includes a first period and / or cause value.

[0353] Step 1408: The access network device sends a UE context release complete message to the mobility management network element. In response, the mobility management network element receives the UE context release complete message.

[0354] Step 1408 is an optional step.

[0355] Step 1409: The terminal device skips performing uplink transmission during the time period corresponding to the periodic TAU cycle or periodic registration cycle based on a cause value.

[0356] In other words, when there is an uplink transmission requirement, the terminal device will skip performing uplink transmission during the time period corresponding to the periodic TAU cycle or periodic registration cycle, based on a cause value.

[0357] Step 1409 is an optional step.

[0358] Step 1409 is performed when step 1404 or step 1407 contains a causal value.

[0359] According to the aforementioned solution, in the procedure for releasing the terminal device, when the terminal device enters an idle state, a periodic TAU cycle or periodic registration cycle update is triggered, ensuring that the terminal device sleeps during periods when it is not covered by the satellite network after entering the idle state, thereby reducing the terminal device's power consumption.

[0360] Figure 15 is a schematic flowchart of a communication method according to an embodiment of the present application. This solution is a specific implementation of the embodiment corresponding to Figure 12. For example, in a 4G application scenario, the mobility management network element and the access network device may be an MME and an eNB, respectively. For example, in a 5G application scenario, the mobility management network element and the access network device may be an AMF and a gNB, respectively.

[0361] The method includes the following steps:

[0362] Step 1501: Based on the terminal device's satellite coverage information, the terminal device determines that it is about to lose satellite network coverage and uses the access network device to send a TAU request or Mobility Registration Update request to the mobility management network element. In response, the mobility management network element receives the TAU request or Mobility Registration Update request.

[0363] Optionally, the terminal device's position can be fixed, or the terminal device's movement trajectory can be fixed.

[0364] In one implementation, a terminal device may receive satellite coverage information for the terminal device from an access network device, a third party, or a core network device. In another implementation, a terminal device may receive cell ephemeris information from an access network device, a third party, or a core network device, and then determine the terminal device's satellite coverage information based on the cell ephemeris information.

[0365] In 4G, access network devices send TAU requests to the Mobility Management Network element (i.e., MME). In 5G, access network devices send mobility registration update requests to the Mobility Management Network element (i.e., AMF).

[0366] Step 1502 is the same as step 1403.

[0367] Step 1503: The mobility management network element sends a TAU acceptance message or a mobility registration renewal acceptance message to a terminal device using an access network device, wherein the TAU acceptance message includes a periodic TAU cycle, or the mobility registration renewal acceptance message includes a periodic registration cycle. In response, the terminal device receives the TAU acceptance message or the mobility registration renewal acceptance message.

[0368] In 4G, access network devices send TAU requests to mobility management network elements (i.e., MMEs). In response, the MME sends a TAU acceptance message to the access network devices. In 5G, access network devices send mobility registration renewal requests to mobility management network elements (i.e., AMFs). In response, the AMF sends a mobility registration renewal acceptance message to the access network devices.

[0369] Optionally, the TAU acceptance message or the mobility registration renewal acceptance message may further include a first period. For the meaning of the first period, see the explanation in step 1403.

[0370] Optionally, the TAU acceptance message or mobility registration renewal acceptance message may further include a cause value. For the meaning of the cause value, please refer to the explanation in step 1403.

[0371] Step 1504: The terminal device skips performing uplink transmission during the time period corresponding to the periodic TAU cycle or periodic registration cycle based on a cause value.

[0372] In other words, when there is an uplink transmission requirement, the terminal device will skip performing uplink transmission during the time period corresponding to the periodic TAU cycle or periodic registration cycle, based on a cause value.

[0373] Step 1504 is an optional step. Step 1504 is performed when step 1503 includes a causal value.

[0374] According to the aforementioned solution, before the terminal device is about to lose satellite network coverage, the terminal device triggers a periodic TAU procedure or periodic registration procedure, so the mobility management network element determines the periodic TAU cycle or periodic registration cycle based on the terminal device's satellite coverage information. The time period corresponding to the periodic TAU cycle or periodic registration cycle includes a period of time when the terminal device is not covered by the satellite network to ensure that the terminal device sleeps during the time period when it is not covered by the satellite network after entering an idle state, thereby reducing the terminal device's power consumption.

[0375] Figure 16(a) is a schematic flowchart of a communication method according to an embodiment of the present application. This solution is a specific implementation of the embodiment corresponding to Figure 4. The method includes the following steps:

[0376] Step 1601a: The terminal device obtains satellite coverage information for the terminal device.

[0377] Optionally, the terminal device's position can be fixed, or the terminal device's movement trajectory can be fixed.

[0378] In one implementation, a terminal device may receive satellite coverage information from an access network device, a third party, or a core network device (e.g., a mobility management network element). In another implementation, a terminal device may receive ephemeris information from an access network device, a third party, or a core network device, and then determine its satellite coverage information based on that ephemeris information.

[0379] A terminal device may receive satellite coverage information or ephemeris information from an access network device using the following method: The terminal device receives an RRC message from the access network device, which contains satellite coverage information or ephemeris information for the terminal device. The RRC message may be an RRC reconfiguration message or a broadcast message.

[0380] A terminal device may receive satellite coverage information or ephemeris information from a mobility management network element using the following method: The terminal device receives a NAS message from the mobility management network element, the NAS message containing satellite coverage information or ephemeris information for the terminal device. Optionally, the NAS message further includes one or more of the following: an eDRX cycle, a periodic TAU cycle, or a periodic registration cycle. The NAS message may be a registration acceptance message, an attach acceptance message, or a TAU acceptance message.

[0381] The satellite coverage information of the terminal device may be ephemeris information.

[0382] Step 1602a: The terminal device decides whether to initiate periodic TAU, periodic registration, or uplink data transmission based on the terminal device's satellite coverage information.

[0383] Specifically, the terminal device determines, based on its satellite coverage information, whether it is covered by the satellite network, i.e., whether it is currently covered by the satellite network. When the terminal device is covered by the satellite network, it initiates periodic TAU, periodic registration, or uplink data transmission. When the terminal device is not covered by the satellite network, it does not initiate periodic TAU, periodic registration, or uplink data transmission.

[0384] In the implementation, the terminal device may further receive indication information from an access network device or a mobility management network element. The indication information tells the terminal device to check its satellite network coverage status when it has an uplink transmission requirement and to perform an uplink transmission based on the satellite network coverage status. The uplink transmission requirement as herein includes, but is not limited to, one or more of periodic TAUs, periodic registrations, or uplink data transmissions. When the terminal device receives the indication information, step 1602a may be as follows: The terminal device decides whether to initiate a periodic TAU, a periodic registration, or an uplink data transmission based on its satellite coverage information and the indication information. If the terminal device is covered by the satellite network, the terminal device initiates a periodic TAU, a periodic registration, or an uplink data transmission. If the terminal device is not covered by the satellite network, the terminal device does not initiate a periodic TAU, a periodic registration, or an uplink data transmission.

[0385] According to the aforementioned solution, when a terminal device is not covered by the satellite network, it will skip performing uplink transmission even if there is an uplink transmission requirement. This avoids unnecessary and ineffective network connectivity operations such as cell scanning and cell selection, thereby reducing the power consumption of the terminal device.

[0386] Optionally, the embodiment corresponding to Figure 16(a) can be applied to scenarios where the terminal device is not covered by the satellite network for extended periods. This is because there is a limit to the cycle time of periodic TAU or periodic registration, and it may not be very large. Therefore, when the terminal device is not covered by the satellite network for a long period, it is necessary to perform periodic TAU or periodic registration. In this case, power consumption losses are significant because the terminal device is not covered by the satellite network and continuously performs cell scanning and cell selection. Therefore, to avoid unnecessary periodic TAU or periodic registration when an idle terminal device is not covered by the satellite network, in the embodiment corresponding to Figure 16(a), the terminal device does not perform periodic TAU or periodic registration and uplink data transmission when the terminal device is not covered by the satellite network, so that signaling interaction between the terminal device and mobility management network elements can be minimized, and power consumption of the terminal device is reduced.

[0387] Figure 16(b) is a schematic flowchart of a communication method according to an embodiment of the present application. This solution is a specific implementation of the embodiment corresponding to Figure 4. The method includes the following steps:

[0388] Step 1601b: The mobility management network element obtains satellite coverage information for the terminal device.

[0389] In the implementation, the mobility management network element may receive satellite coverage information for terminal devices from terminal devices, access network devices, or third parties, and the satellite coverage information for terminal devices may be ephemeris information.

[0390] In an alternative implementation, a mobility management network element may receive ephemeris information from a terminal device, an access network device, or a third party, and then determine the satellite coverage information of the terminal device based on that ephemeris information.

[0391] Step 1602b: The mobility management network element determines whether to deregister (or detach) the terminal device based on the terminal device's satellite coverage information.

[0392] Specifically, when the deregistration timer (or detachment timer) corresponding to a terminal device expires, a decision is made based on the terminal device's satellite coverage information whether or not to deregister (or detach) the terminal device. If the terminal device is covered by the satellite network, the mobility management network element performs the deregistration (or detachment) of the terminal device. If the terminal device is not covered by the satellite network, the mobility management network element skips performing the deregistration (or detachment) of the terminal device.

[0393] Skipping the deregistration of a terminal device may also be understood as maintaining the terminal device's registration status without change. Skipping the detachment of a terminal device may also be understood as maintaining the terminal device's attachment status without change, i.e., keeping the terminal device always in an EMM-registered state. Optionally, if the terminal device is not deregistered, this responds if the terminal device is not covered by the satellite network.

[0394] According to the aforementioned solution, the switching of terminal device status between registration and unregistration or between attachment and detachment is reduced, which can reduce signaling interactions between the terminal device and the network, and thus reduce power consumption of the terminal device.

[0395] In terms of implementation methods, the embodiment corresponding to Figure 16(a) and the embodiment corresponding to Figure 16(b) can be combined for implementation.

[0396] To implement the functions in the embodiments described above, a mobility management network element, access network device, or terminal device may be understood to include a corresponding hardware structure and / or software module for performing the function. Those skilled in the art will readily recognize that, with respect to the combination of units and method steps in the examples described in the embodiments disclosed herein, the application can be implemented using hardware or a combination of hardware and computer software. Whether the function is implemented using hardware or using hardware driven by computer software depends on the specific application scenario and the design constraints of the technical solution.

[0397] Figures 17 and 18 are schematic diagrams of possible communication device structures according to embodiments of the present application. These communication devices may be configured to implement the functions of the mobility management network element, access network device, or terminal device of the method embodiment described above, and thus the beneficial effects of the method embodiment described above can also be achieved. In embodiments of the present application, the communication device may be a mobility management network element, an access network device, or a terminal device, or it may be a module (e.g., a chip) applied to a mobility management network element, an access network device, or a terminal device.

[0398] As shown in Figure 17, the communication device 1700 includes a processing unit 1710 and a transceiver unit 1720. The communication device 1700 is configured to implement the functions of the mobility management network element, access network device, or terminal device of the method embodiment described above.

[0399] In the first embodiment, the communication device is configured to perform the operation of a mobility management network element. The processing unit 1710 is configured to determine sleep time information for a terminal device based on the terminal device's satellite coverage information, where the satellite coverage information indicates a period of time during which the terminal device is covered by the satellite network and / or a period of time during which the terminal device is not covered by the satellite network, and the sleep time period corresponding to the sleep time information includes a period of time during which the terminal device is not covered by the satellite network. The transceiver unit 1720 is configured to transmit the sleep time information to the terminal device.

[0400] In possible implementations, the processing unit 1710 is configured to determine one or more of the terminal device's eDRX cycle, periodic TAU cycle, or periodic registration cycle based on satellite coverage information. Sleep time information includes a sleep start time, which falls within the eDRX cycle, periodic TAU cycle, or periodic registration cycle.

[0401] Possible implementations include sleep time information that includes sleep start time and sleep end time, or sleep time information that includes sleep start time and sleep duration.

[0402] In a possible implementation, the processing unit 1710 is configured to receive satellite coverage information using the transceiver unit 1720. Alternatively, the transceiver unit 1720 receives ephemeris information of the satellite cell where the terminal device is located and determines satellite coverage information based on the ephemeris information.

[0403] In possible implementations, the processing unit 1710 is configured to determine whether the terminal device's position is fixed or whether the terminal device's movement trajectory is fixed.

[0404] In a possible implementation, the processing unit 1710 is configured to determine, based on satellite coverage information, that the terminal device is not covered by the satellite network when the deregistration timer corresponding to the terminal device expires, and to skip performing deregistration on the terminal device.

[0405] In a second embodiment, the communication device is configured to perform the operation of a mobility management network element. The processing unit 1710 is configured to determine, based on the satellite coverage information of the terminal device, that the terminal device is not covered by the satellite network when the deregistration timer corresponding to the terminal device expires, the satellite coverage information indicating the time periods during which the terminal device is covered by the satellite network and / or the time periods during which the terminal device is not covered by the satellite network, and the processing unit 1710 is also configured to decide to skip performing deregistration or detachment to the terminal device in response to the terminal device not being covered by the satellite network.

[0406] In a possible implementation, the transceiver unit 1720 is configured to transmit first information to a terminal device, which indicates that the terminal device will perform uplink transmission based on satellite network coverage status when the terminal device has an uplink transmission requirement.

[0407] In a possible implementation, the first information is satellite coverage information, and the first information clearly indicates that when a terminal device has an uplink transmission requirement, the terminal device initiates uplink transmission based on the satellite coverage information.

[0408] In a possible implementation, the transceiver unit 1720 is configured to transmit satellite coverage information to a terminal device, the first information clearly indicating that the terminal device will initiate uplink transmission based on the satellite coverage information when the terminal device has an uplink transmission requirement.

[0409] In possible implementations, uplink transmission requirements include one or more of the following: periodic TAU, periodic registration, or uplink data transmission.

[0410] In a possible implementation, the processing unit 1710 is configured to receive satellite coverage information using the transceiver unit 1720. Alternatively, the transceiver unit 1720 receives ephemeris information of the satellite cell where the terminal device is located and determines satellite coverage information based on the ephemeris information.

[0411] In possible implementations, the processing unit 1710 is configured to determine that the position of the terminal device is fixed, or to determine that the movement trajectory of the terminal device is fixed.

[0412] In a third embodiment, the communication device is configured to perform the operation of a mobility management network element. The processing unit 1710 is configured to determine satellite coverage information for a terminal device, which indicates the period of time during which the terminal device is covered by the satellite network and / or the period of time during which the terminal device is not covered by the satellite network. The processing unit 1710 is also configured to determine a maximum latency based on the satellite coverage information, which indicates the maximum period of time to wait until the terminal device becomes reachable.

[0413] In a possible implementation, the processing unit 1710 is configured to determine, based on satellite coverage information, that the terminal device is unreachable.

[0414] In a possible implementation, the processing unit 1710 is configured to receive satellite coverage information using the transceiver unit 1720.

[0415] In a possible implementation, the processing unit 1710 is configured to use the transceiver unit 1720 to receive ephemeris information of the satellite cell where the terminal device is located, and to determine satellite coverage information based on the ephemeris information.

[0416] In a possible implementation, the processing unit 1710 is configured to use the transceiver unit 1720 to send a paging message to an access network device, the paging message containing identification information of the terminal device and indicating that the terminal device should be paged. The processing unit 1710 is also configured to use the transceiver unit 1720 to receive a first message from the access network device, the first message containing a paging failure indication and satellite coverage information for the terminal device, the paging failure indication indicating that the reason for the paging failure is that the terminal device is not covered by the satellite network. Optionally, the paging failure indication further indicates that a mobility management network element should perform reachability determination / paging based on the satellite coverage information.

[0417] In possible implementations, the processing unit 1710 is configured to determine that the position of the terminal device is fixed, or to determine that the movement trajectory of the terminal device is fixed.

[0418] In a fourth embodiment, the communication device is configured to perform operations on a terminal device. The transceiver unit 1720 is configured to receive first information indicating that, when the terminal device has an uplink transmission requirement, the terminal device will perform an uplink transmission based on the satellite network coverage status. The processing unit 1710 is configured to determine, based on the first information, that the terminal device is not covered by the satellite network and to skip performing the uplink transmission when the terminal device has an uplink transmission requirement.

[0419] In possible implementations, the first piece of information is satellite coverage information. Satellite coverage information indicates the time periods during which the terminal device is covered by the satellite network and / or the time periods during which the terminal device is not covered by the satellite network. The first piece of information clearly indicates that, when the terminal device has an uplink transmission requirement, the terminal device will initiate uplink transmission based on the satellite coverage information.

[0420] In a possible implementation, the processing unit 1710 is configured to receive satellite coverage information using the transceiver unit 1720. The satellite coverage information indicates the time periods during which the terminal device is covered by the satellite network and / or the time periods during which the terminal device is not covered by the satellite network. The first information clearly indicates that the terminal device will initiate uplink transmission based on the satellite coverage information when the terminal device has an uplink transmission requirement.

[0421] In possible implementations, uplink transmission requirements include one or more of the following: periodic TAU, periodic registration, or uplink data transmission.

[0422] In the fifth embodiment, the communication device is configured to perform operations on the terminal device. The transceiver unit 1720 is configured to receive sleep time information, the sleep time period corresponding to the sleep time information includes the period of time when the terminal device is not covered by the satellite network, the sleep time information is determined based on the satellite coverage information of the terminal device, the satellite coverage information indicates the period of time when the terminal device is covered by the satellite network and / or the period of time when the terminal device is not covered by the satellite network. The processing unit 1710 is configured to perform sleep based on the sleep time information.

[0423] In possible implementations, sleep time information includes the sleep start time, which falls within the terminal device's eDRX cycle, the terminal device's periodic TAU cycle, or the terminal device's periodic registration cycle.

[0424] Possible implementations include sleep time information that includes sleep start time and sleep end time, or sleep time information that includes sleep start time and sleep duration.

[0425] In the sixth embodiment, the communication device is configured to perform the operation of the access network device. The processing unit 1710 is configured to acquire satellite coverage information or ephemeris information of the satellite cell, where the satellite coverage information indicates the period of time during which the satellite cell is covered by the satellite network and / or the period of time during which the satellite cell is not covered by the satellite network. The transceiver unit 1720 is configured to transmit the satellite coverage information or ephemeris information of the satellite cell to the mobility management network element.

[0426] In a possible implementation, the transceiver unit 1720 is configured to transmit satellite coverage information or ephemeris information corresponding to the satellite cell of the access network device to the mobility management network element during the N2 interface setup procedure.

[0427] In a possible implementation, the transceiver unit 1720 is configured to transmit satellite coverage information or ephemeris information of the satellite cell in which the terminal device is located to a mobility management network element during the terminal device registration procedure.

[0428] In a possible implementation, the transceiver unit 1720 is configured to receive paging messages from a mobility management network element, the paging messages containing identification information of a terminal device, and the paging messages indicating that the terminal device should be paged. The processing unit 1710 is configured to determine that the terminal device is unreachable based on satellite coverage information of the satellite cell in which the terminal device is located, and to send a first message to the mobility management network element using the transceiver unit 1720, the first message containing a paging failure indication and satellite coverage information for the terminal device, the paging failure indication indicating that the reason for this paging failure is that the terminal device is not covered by the satellite network. Optionally, the paging failure indication further indicates that the mobility management network element needs to perform reachability determination / paging based on the satellite coverage information.

[0429] In a seventh embodiment, the communication device is configured to perform the operation of a mobility management network element. The processing unit 1710 is configured to determine the periodic TAU cycle of the terminal device based on the terminal device's satellite coverage information, and the transceiver unit 1720 is configured to transmit the periodic TAU cycle to the terminal device. Alternatively, the processing unit 1710 is configured to determine the periodic registration cycle of the terminal device based on the terminal device's satellite coverage information, and the transceiver unit 1720 is configured to transmit the periodic registration cycle to the terminal device, where the satellite coverage information indicates the period of time when the terminal device is covered by the satellite network and / or the period of time when the terminal device is not covered by the satellite network.

[0430] In possible implementations, the time period corresponding to a periodic TAU cycle includes a period during which the terminal device is not covered by the satellite network, or the time period corresponding to a periodic registration cycle includes a period during which the terminal device is not covered by the satellite network.

[0431] In a possible implementation, the processing unit 1710 is further configured to use the transceiver unit 1720 to transmit indication information to an access network device based on satellite coverage information, and the indication information tells the access network device to perform a procedure to release the terminal device.

[0432] In a possible implementation, the processing unit 1710 is configured to determine a first period based on the satellite coverage information of the terminal device, the first period being the period from when the terminal device enters an idle state until when the terminal device enters a sleep state. The transceiver unit 1720 is configured to transmit the first period to the terminal device.

[0433] In a possible implementation, the transceiver unit 1720 is further configured to transmit a causal value to a terminal device, where the causal value is discontinuous satellite coverage.

[0434] In possible implementations, the causal value further indicates that the terminal device skips performing uplink transmission while in sleep mode.

[0435] In possible implementations, the transceiver unit 1720 is configured to send a GUTI reassignment command to the terminal device, the GUTI reassignment command including a periodic TAU cycle, or the transceiver unit 1720 is configured to send a TAU acceptance message to the terminal device, the TAU acceptance message including a periodic TAU cycle.

[0436] In possible implementations, the transceiver unit 1720 is configured to send a configuration update command to a terminal device, the configuration update command including a periodic registration cycle, or the transceiver unit 1720 is configured to send a mobility registration update acceptance message to a terminal device, the mobility registration update acceptance message including a periodic registration cycle.

[0437] In the eighth embodiment, the communication device is configured to perform operations on a terminal device. The transceiver unit 1720 is configured to receive periodic TAU cycles from a mobility management network element, and the processing unit 1710 is configured to perform periodic TAU based on the periodic TAU cycle, with the time period corresponding to the periodic TAU cycle including a time period during which the terminal device is not covered by the satellite network. Alternatively, the transceiver unit 1720 is configured to receive periodic registration cycles from a mobility management network element, and the processing unit 1710 is configured to perform periodic registration based on the periodic registration cycle, with the time period corresponding to the periodic registration cycle including a time period during which the terminal device is not covered by the satellite network.

[0438] In possible implementations, the periodic TAU cycle or periodic registration cycle is determined based on the terminal device's satellite coverage information, which indicates the time periods during which the terminal device is covered by the satellite network and / or the time periods during which the terminal device is not covered by the satellite network.

[0439] In possible implementations, the processing unit 1710 is configured to use the transceiver unit 1720 to send a TAU request to the mobility management network element based on the terminal device's satellite coverage information before the transceiver unit 1720 receives a periodic TAU cycle from the mobility management network element, or to use the transceiver unit 1720 to send a mobility registration update request to the mobility management network element based on the terminal device's satellite coverage information before the transceiver unit 1720 receives a periodic registration cycle from the mobility management network element, the satellite coverage information indicating the time periods during which the terminal device is covered by the satellite network and / or the time periods during which the terminal device is not covered by the satellite network.

[0440] In a possible implementation, the transceiver unit 1720 is further configured to receive a first period from a mobility management network element, the first period being the period from when the terminal device enters an idle state until when the terminal device enters a sleep state, and the first period being determined based on the terminal device's satellite coverage information.

[0441] In a possible implementation, the transceiver unit 1720 is configured to receive a causal value from a mobility management network element, where the causal value is discontinuous satellite coverage.

[0442] In possible implementations, the cause value further indicates that the terminal device will skip performing uplink transmission while in sleep mode. When an uplink transmission requirement exists, the cause value determines whether to skip performing the uplink transmission.

[0443] In the ninth embodiment, the communication device is configured to perform the operations of an access network device. Processing unit 1710 is configured to use transceiver unit 1720 to send a context release request to a mobility management network element based on satellite coverage information of a terminal device, the context release request is used to request the mobility management network element to release the context of the terminal device, the satellite coverage information indicating a period of time during which the terminal device is covered by the satellite network and / or a period of time during which the terminal device is not covered by the satellite network. Transceiver unit 1720 is further configured to receive a periodic TAU cycle from the mobility management network element and to send a periodic TAU cycle to the terminal device, the period of time corresponding to the periodic TAU cycle includes a period of time during which the terminal device is not covered by the satellite network. Alternatively, transceiver unit 1720 is further configured to receive a periodic registration cycle from the mobility management network element and to send a periodic registration cycle to the terminal device, the period of time corresponding to the periodic registration cycle includes a period of time during which the terminal device is not covered by the satellite network.

[0444] For a more detailed description of the processing unit 1710 and the transceiver unit 1720, please refer directly to the relevant descriptions in the method embodiments. Further details are not described again herein.

[0445] As shown in Figure 18, the communication device 1800 includes a processor 1810. Optionally, the communication device 1800 may further include an interface circuit 1820. The processor 1810 and the interface circuit 1820 are coupled to each other. The interface circuit 1820 may be understood to be a transceiver or an input / output interface. Optionally, the communication device 1800 may further include a memory 1830 configured to store instructions executed by the processor 1810, or input data required by the processor 1810 to execute an instruction, or data generated after the processor 1810 has executed an instruction.

[0446] When the communication device 1800 is configured to implement the method embodiment described above, the processor 1810 is configured to perform the functions of the processing unit 1710, and the interface circuit 1820 is configured to perform the functions of the transceiver unit 1720.

[0447] The processor in the embodiments of this application may be a central processing unit (CPU), or may be another general-purpose processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field programmable gate array (FPGA), or another programmable logic device, transistor logic device, hardware component, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0448] The method steps in embodiments of this application may be implemented in hardware or by a processor executing software instructions. The software instructions may include corresponding software modules. The software modules may 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, removable hard disks, CD-ROMs, or any other form of storage medium well known in the art. For example, the storage medium may be coupled to a processor so that the processor can read information from or write information to the storage medium. Certainly, the storage medium may be a component of the processor. The processor and storage medium may be located within an ASIC. In addition, the ASIC may be located in a base station or terminal. Certainly, the processor and storage medium may exist as discrete components in the base station or terminal.

[0449] All or part of the embodiments described above may be implemented using software, hardware, firmware, or any combination thereof. If software is used to implement an embodiment, all or part of the embodiment may be implemented in the form of a computer program product. A computer program product includes one or more computer programs or instructions. When a computer program or instruction is loaded into a computer and executed, the procedures or functions according to the embodiments of this application are implemented in whole or in part. The computer may be a general-purpose computer, a dedicated computer, a computer network, a base station, user equipment, or another programmable device. The computer program or instruction may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer program or instruction may be transmitted by wire or wirelessly from one website, computer, server, or data center to another website, computer, server, or data center. The computer-readable storage medium may be any available medium accessible by a computer, or a data storage device such as a server or data center that integrates one or more available media. The usable media may be magnetic media (e.g., floppy disks, hard disks, or magnetic tapes), optical media (e.g., digital video discs), or semiconductor media (e.g., solid-state disks). The computer-readable storage medium may be volatile or non-volatile, or may include both types of storage media, namely volatile and non-volatile storage media.

[0450] In the embodiments of this application, unless otherwise specified or unless there is a logical inconsistency, the terminology and / or descriptions in different embodiments are consistent and may be referenced to one another, and the technical features in different embodiments may be combined on the basis of their internal logical relationships to form new embodiments.

[0451] In this application, “at least one” means one or more, and “multiple” means two or more. The term “and / or” describes a relationship between related subjects and can indicate three relationships. For example, A and / or B may indicate: only A exists, both A and B exist, and only B exists, where A and B may be singular or plural. In text descriptions in this application, the letter “ / ” generally indicates an “or” relationship between related subjects. In mathematical formulas in this application, the letter “ / ” indicates a “division” relationship between related subjects.

[0452] The various numbers in the embodiments of this application are used merely for illustrative purposes and not to limit the scope of the embodiments. The sequence numbers of the processes described above do not indicate the order of execution, and the order of execution of the processes is determined based on the function and internal logic of the processes.

Claims

1. A step of receiving satellite coverage information for a terminal device, wherein the satellite coverage information indicates a period of time during which the terminal device is covered by the satellite network, and / or a period of time during which the terminal device is not covered by the satellite network. Steps include determining, based on satellite coverage information, to skip performing uplink transmission when the terminal device has an uplink transmission requirement, wherein the uplink transmission requirement includes one of periodic TAU, periodic registration, or uplink data transmission. Includes, A communication method comprising the step of deciding to skip performing an uplink transmission based on the satellite coverage information, which includes the step of deciding to skip performing the uplink transmission when it is determined that the terminal device is not covered by the satellite network based on the satellite coverage information.

2. The step of receiving the aforementioned satellite coverage information is: The steps include receiving the aforementioned satellite coverage information from an access network device, a third party, or a mobility management network element. The method according to claim 1.

3. A step of transmitting satellite coverage information for a terminal device to the terminal device via an access network device, a third party, or a mobility management network element, wherein the satellite coverage information indicates a period of time during which the terminal device is covered by the satellite network, and / or a period of time during which the terminal device is not covered by the satellite network. Steps include determining, based on satellite coverage information, to skip performing uplink transmission when the terminal device has an uplink transmission requirement, wherein the uplink transmission requirement includes one of periodic TAU, periodic registration, or uplink data transmission. Includes, A communication method comprising the step of deciding to skip performing an uplink transmission based on the satellite coverage information, which includes the step of deciding to skip performing the uplink transmission when it is determined, based on the satellite coverage information, that the terminal device is not covered by the satellite network.

4. A communication device comprising a processor and an interface circuit, wherein the interface circuit is configured to receive a signal from a communication device other than the communication device and transmit the signal to the processor, or to transmit a signal from the processor to a communication device other than the communication device, and the processor is configured to carry out the method according to claim 1 or 2 by using logic circuits or by executing code instructions.

5. A computer-readable storage medium, wherein the storage medium stores a computer program or instruction, and the method according to claim 1 or 2 is performed when the computer program or instruction is executed by a communication device.

6. A computer program wherein, when the computer program is executed by a communication device, the method according to claim 1 or 2 is performed.

7. An access network device, a third party, or a mobility management network element is configured to transmit satellite coverage information for a terminal device to the terminal device, wherein the satellite coverage information indicates a period of time during which the terminal device is covered by the satellite network, and / or indicates a period of time during which the terminal device is not covered by the satellite network. The terminal device is configured to determine, based on the satellite coverage information, to skip performing uplink transmission when the terminal device has an uplink transmission requirement, wherein the uplink transmission requirement includes one of periodic TAU, periodic registration, or uplink data transmission. A communication system including, The terminal device is configured to decide to skip performing the uplink transmission when it determines, based on the satellite coverage information, that the terminal device is not covered by the satellite network. Communication system.

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