WO2025200906A1 - Communication method and communication apparatus - Google Patents

Abstract

A communication method and a communication apparatus, which can be applied to the technical field of satellite communications. The method comprises: when a terminal device leaves the coverage range of a first network device that provides a service for the terminal device, the terminal device changes from a connected state to a first state. When the terminal device is within the coverage range of a second network device, the terminal device sends to the second network device a first request message for requesting to access the second network device. The first state comprises any one of a suspended connected state of an access stratum of the terminal device, a suspended idle state, or an inactive state. Hence, when the terminal device leaves the coverage range of the first network device, the terminal device enters the first state, and the terminal device can still retain context information of the terminal device in the first state, so that the terminal device can correctly access the second network device and normal communication between the terminal device and a network is ensured.

Description

Communication method and communication device

This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on March 27, 2024, with application number 202410365453.8 and invention name “Communication Method and Communication Device”, the entire contents of which are incorporated by reference into this application.

Technical Field

The present application relates to the field of communication technology, and more specifically, to a communication method and a communication device.

Background Art

With the development of communication technology, the fifth-generation mobile network (5G) has introduced satellite communications. Satellite communications can provide communication services to areas that are difficult for terrestrial networks to cover, such as oceans and forests, and enhance the reliability of 5G communications. Due to the mobility of satellites, their coverage range varies over time. For example, due to satellite mobility, within a certain period of time, a terminal device may leave the coverage area of the satellite providing service to the terminal device. This means that the satellite cannot provide service to the terminal device during that period of time. At this time, the terminal device needs to connect to a new satellite to ensure normal communication between the terminal device and the network.

Considering the security of information transmission between terminal devices and satellites, the information transmitted between the two devices is often encrypted. In the scenarios currently under study, satellites provide discontinuous coverage of terminal devices, while providing continuous coverage of ground gateways. This means that satellites can connect to core network devices in real time through ground gateways to obtain relevant information about terminal devices, thereby ensuring key consistency between the satellite and terminal devices and ensuring normal communication between the satellite and terminal devices. However, in store and forward (S&F) scenarios, satellites provide discontinuous coverage relative to both ground gateways and terminal devices. Satellites cannot cover both ground gateways and terminal devices simultaneously. Each time a terminal device connects to a satellite, it re-derives the key, resulting in the inability to align the transmission key between the satellite and terminal device, making normal communication impossible. Therefore, in S&F scenarios, how to ensure normal communication between terminal devices and the network is a current research hotspot.

Summary of the Invention

The present application provides a communication method and a communication device that can ensure normal communication between a terminal device and a network in an S&F scenario.

In a first aspect, a communication method is provided, which can be executed by a terminal device, or can also be executed by a component of the terminal device (such as a chip or circuit), which is not limited in this application. The following is an introduction using a terminal device as an example.

The method includes: when a terminal device leaves the coverage of a first network device that provides services for the terminal device, the terminal device changes from a connected state to a first state, wherein the first state includes any one of the following: a connected state suspended by the access layer AS of the terminal device, a suspended idle state, or an inactive state; the terminal device sends a first request message to a second network device, wherein the first request message is used to request access to the second network device, and the first request message includes identification information of the terminal device, wherein the first network device and the second network device are non-terrestrial network devices.

It should be understood that the first network device and the second network device are the same or different network devices.

[Corrected 12.03.2025 in accordance with Article 91]
It should be understood that the access stratum (AS) suspended connection state of a terminal device is a special connection state in which the terminal device still retains its context information. The access stratum (AS) suspended connection state of the terminal device can be understood as the terminal device remaining in the connected state and ceasing AS-layer processing operations. For example, the terminal device stops detecting radio link failures (RLFs), stops measuring, stops monitoring paging, and so on.

It should be understood that the idle state (IDLE with suspended) is a special idle state. In the idle state, the terminal device retains the context information of the terminal device and does not release the context information of the terminal device.

It should be understood that the first network device and the second network device are non-terrestrial network devices. The first network device and the second network device can be satellites, drones, etc., and this application does not limit this.

It should be understood that the premise for the terminal device to send the first request information to the second network device is that the terminal device is located within the coverage of the second network device, or in other words, the second network device has moved to an area that can cover the terminal device.

According to the method provided in the present application, when the terminal device leaves the coverage of the first network device, that is, when the source network device that provides services to the terminal device (such as the first network device) no longer provides services to the terminal device, the terminal device changes from the connected state to the first state. The terminal device retains the context information of the terminal device in the first state, which facilitates correct access to the new target network device that provides services to the terminal device (such as the second network device), thereby ensuring normal communication between the terminal device and the network.

In combination with the first aspect, in some possible implementations, the terminal device receives first information from a first network device, the first information includes at least one third network device, the at least one third network device includes a second network device and/or a first network device, and each of the at least one third network device is a non-terrestrial network device.

It should be understood that the first network device indicates at least one third network device to the terminal device through the first information. The at least one third network device can be understood as a network device that subsequently provides services to the terminal device, or the at least one third network device can also be understood as a potential network device that the terminal device can subsequently access (or that the terminal device is allowed to access).

It should also be understood that, when the at least one third network device included in the first information is the first network device, the terminal device sends the first request information to the second network device, which is the same network device as the first network device. The terminal device requests access to the first network device based on the first information.

It should also be understood that when the at least one third network device included in the first information includes a first network device and a second network device, the above-mentioned terminal device sends a first request information to the second network device, the second network device and the first network device are different network devices, and the terminal device selects the second network device from the first network device and the second network device to request access.

In combination with the first aspect, in some possible implementation methods, before the terminal device sends the first request information to the second network device, the method also includes: the terminal device receives first indication information from the first network device, the first indication information being used to indicate that when the terminal device leaves the coverage of the first network device and re-enters the coverage of the first network device, the terminal device accesses the first network device, wherein the first network device and the second network device are the same network device (or the first network device and the second network device are called the same).

In one possible implementation, the first indication information is used to instruct the terminal device to access a first network device and prohibit access to network devices other than the first network device.

It should be understood that when the terminal device leaves the coverage of the first network device, the terminal device needs to wait until it re-enters the coverage of the first network device according to the first indication information before accessing the first network device. The terminal device cannot access other network devices except the first network device.

In combination with the first aspect, in some possible implementations, the terminal device sends first request information to the second network device, including: the terminal device receives indication information from at least one third network device for indicating the available area of each third network device in the at least one third network device; the terminal device determines to send the first request information to the second network device based on the first information and the indication information for indicating the available area of each third network device in the at least one third network device.

In combination with the first aspect, in some possible implementation methods, the first information also includes indication information for indicating the available area of each third network device in the at least one third network device, and the terminal device sends the first request information to the second network device, including: the terminal device determines to send the first request information to the second network device based on the first information.

It should be understood that, in a case where the at least one third network device includes a first network device, the first information includes indication information for indicating an available area of the first network device.

In the above technical solution, the terminal device selects the second network device among at least one third network device for access through the available area of each third network device among the at least one third network device, so that the terminal device can reasonably select a new network device to prepare for access, thereby ensuring the communication quality of the terminal device.

In combination with the first aspect, in some possible implementations, at least one third network device includes a first network device, and the first information also includes indication information for indicating an available area of the first network device. Based on the first information, determining to send first request information to the second network device includes: when the terminal device is not located within the available area of the first network device, determining to send the first request information to the second network device.

It should be understood that the at least one third network device included in the first information includes the first network device and indication information of the available area of the first network device. When the terminal device is not located in the available area of the first network device, the terminal device can send the first request information to other network devices (such as the second network device). The terminal device is located within the coverage area of the second network device, and the second network device can be a network device in the at least one third network device, or the second network device is not a network device in the at least one third network device. This application does not limit this.

In combination with the first aspect, in some possible implementation methods, the terminal device sends the first request information to the second network device, including: sending the first request information to the second network device when a first condition is met, the first condition including: the second network device is the network device with the smallest delay among the at least one third network device, and/or the second network device has the context information of the terminal device.

In the above technical solution, the terminal device selects a network device (such as a second network device) that meets the first condition from at least one third network device through the first condition to access, so that the terminal device can reasonably select a new network device to prepare for access, thereby ensuring the communication quality of the terminal device.

In combination with the first aspect, in some possible implementations, the first information also includes one or more of the following: ephemeris information of each third network device in at least one third network device, location information of each third network device in at least one third network device connected to the gateway, time information of each third network device in at least one third network device connected to the gateway, or whether each third network device in at least one third network device has context information of the terminal device.

In combination with the first aspect, in some possible implementation methods, the identification information of the terminal device includes: a cell radio network temporary identifier (C-RNTI) of the terminal device in a first cell, where the first cell is a cell that provides services to the terminal device within the coverage of the first network device; the identification information of the terminal device also includes one or more of the following: a physical cell ID (PCI) of the first cell, location information of the terminal device, identification information of the first network device, or identification information of the first cell.

In combination with the first aspect, in some possible implementations, the method also includes: the terminal device receives a first response message from the second network device, the first response message is used to respond to the first request message, and the first response message includes a next hop chaining count (NCC); the terminal device communicates with the second network device according to a key, and the key is determined according to the NCC.

In the above technical solution, the terminal device determines the key according to the NCC in the first response information, and performs encrypted communication with the second network device through the key, thereby ensuring secure communication between the terminal device and the second network device.

In combination with the first aspect, in some possible implementation methods, before the terminal device sends the first request information to the second network device, the method also includes: the terminal device sends the first request information to other network devices in at least one third network device except the second network device; in the event that the terminal device fails to access other networks in at least one third network device except the second network device, the terminal device sends the first request information to the second network device.

In the above technical solution, if any of the at least one third network devices that the terminal device attempts to access fails, the terminal device remains in the first state, preserving the terminal device's context. The terminal device further sends a first request message for access to the other network devices in the at least one third network device in the first message, excluding the third network device, thereby ensuring that the terminal device successfully selects a network device for access and maintaining normal communication between the terminal device and the network.

In a second aspect, a communication method is provided, which can be executed by a first network device, or can also be executed by a component (such as a chip or circuit) of the first network device, which is not limited in this application. The following is an introduction using the first network device as an example.

The method includes: a first network device sends first indication information to a terminal device, the first indication information is used to indicate that the terminal device accesses the first network device when the terminal device leaves the coverage of the first network device and re-enters the coverage of the first network device; the first network device receives first request information from the terminal device, the first request information is used to request access to the first network device, wherein the first network device is a non-terrestrial network device.

According to the method provided in the present application, the first network device instructs the terminal device through the first indication information: when the terminal device leaves the coverage of the first network device, the terminal device needs to wait until it re-enters the coverage of the first network device, and the terminal device accesses the first network device.

In a third aspect, a communication method is provided, which can be executed by a first network device, or by a component (such as a chip or circuit) of the first network device, which is not limited in this application. The following is an introduction using the first network device as an example.

The method includes: a first network device sends first information to a terminal device, the first information includes at least one third network device and indication information of an available area of each of the at least one third network device, the at least one third network device includes a second network device and/or the first network device, and each of the at least one third network device is a non-terrestrial network device.

In a fourth aspect, a communication method is provided, which can be executed by a first network device, or can also be executed by a component (such as a chip or circuit) of the first network device, which is not limited in this application. The following is an introduction using the first network device as an example.

The method includes: a first network device sends first information to a terminal device, the first information includes at least one third network device, the at least one third network device includes a first network device and a second network device, the first information also includes indication information for indicating an available area of the first network device, and each third network device in the at least one third network device is a non-terrestrial network device.

In a fifth aspect, a communication method is provided, which can be executed by a first network device, or can also be executed by a component (such as a chip or circuit) of the first network device, which is not limited in this application. The following is an introduction using the first network device as an example.

The method includes: a first network device sends first information to a terminal device, the first information includes at least one third network device; the first network device sends second information to a core network device, the second information includes first context information of the terminal device, the first context information of the terminal device includes identification information of the terminal device, wherein the first network device and the at least one third network device are non-terrestrial network devices, and when the first network device has an unused next hop (next hop, HH), the first context information of the terminal device also includes: a key and next hop chain calculation NCC, the key is determined by the first network device according to the NH, or, when the first network device does not have an unused NH, the first context information of the terminal device also includes: second indication information, the second indication information is used to instruct the core network device to determine the NH and the NCC.

Among them, the first network device has an unused NH, which can be understood as: the information locally stored in the first network device includes the unused NH; similarly, the first network device does not have an unused NH, which can be understood as: the information locally stored in the first network device does not include the unused NH.

In a possible implementation, the second indication information is an explicit information element or message, for example, the second indication information indicates that the first network device does not have an unused NH.

In another possible implementation, the second indication information indicates that the first network device does not carry the key and/or NCC in the first context message, and the second indication information implicitly instructs the core network device to determine the NH and NCC.

In combination with the fifth aspect, in some possible implementation methods, before the first network device sends the second information to the core network device, the method also includes: the first network device receives a second request information from the core network device, the second request information requests to obtain the first context information of the terminal device, and the second request information includes the identification information of the terminal device.

In combination with the fifth aspect, in some possible implementation methods, the identification information of the terminal device includes: the cell radio network temporary identification C-RNTI of the terminal device in the first cell, the first cell is a cell that provides services to the terminal device within the coverage of the first network device; the identification information of the terminal device also includes one or more of the following: the physical cell identification PCI of the first cell, the location information of the terminal device, the identification information of the first network device, or the identification information of the first cell.

In combination with the fifth aspect, in some possible implementations, the first information also includes one or more of the following: ephemeris information of each third network device in at least one third network device, location information of each third network device in at least one third network device connected to the gateway, time information of each third network device in at least one third network device connected to the gateway, or whether each third network device in at least one third network device has context information of the terminal device.

In combination with the fifth aspect, in some possible implementations, the second information further includes: identification information of each third network device in the at least one third network device.

In a sixth aspect, a communication method is provided, which can be executed by a core network device, or can also be executed by a component of the core network device (such as a chip or circuit), which is not limited in this application. The following is an introduction using a core network device as an example.

The method includes: a core network device receives second information from a first network device, the second information includes first context information of a terminal device, and the first context information of the terminal device includes identification information of the terminal device; the core network device sends the second context information of the terminal device to at least one third network device, the second context information of the terminal device includes a key and an NCC, or the second context information of the terminal device includes an NCC and a next hop NH, wherein the first network device and the at least one third network device are non-terrestrial network devices.

It should be understood that the key included in the second context information of the terminal device is from the first context information of the terminal device, and the key is determined by the first network device according to its own unused NH.

It should be understood that the sixth aspect corresponds to some implementation methods of the above-mentioned first to fifth aspects. The technical effects and related introductions can be found in the detailed introductions of the above-mentioned first to fifth aspects, and will not be repeated here.

In combination with the sixth aspect, in some possible implementations, when the first network device has an unused NH, the first context information of the terminal device further includes: a key and an NCC.

In combination with the sixth aspect, in some possible implementation methods, when the first network device does not have an unused NH, the first context information of the terminal device also includes: second indication information, the second indication information is used to instruct the core network device to determine the NH and NCC, or, when the first context information of the terminal device does not include the second indication information, the key and the NCC, the core network device determines the NH and NCC.

In combination with the sixth aspect, in some possible implementation methods, the core network device sends the second context information of the terminal device to at least one third network device, including: the core network device receives a third request information from a second network device in at least one third network device, the third request information requests to obtain the second context information of the terminal device, and the third request information includes identification information of the terminal device; the core network device sends the second context information of the terminal device to the second network device.

In combination with the sixth aspect, in some possible implementation methods, the method also includes: the core network device receives third indication information from a second network device in at least one third network device, and the third indication information is used to indicate that the terminal device has successfully accessed the second network device; the core network device sends release indication information to other network devices in at least one third network device except the second network device based on the third indication information, and the release indication information is used to indicate the release of the second context information of the terminal device.

In the above technical solution, when the terminal device accesses a new network device (for example, a second network device), the second network device sends a third indication message to the core network device to indicate that the terminal device has successfully accessed the second network device, and the core network device sends a release indication message to other network devices in the first information to indicate the release of the terminal device context information, thereby saving resource overhead of other network devices.

In a seventh aspect, a communication method is provided, which can be executed by a second network device, or can also be executed by a component (such as a chip or circuit) of the second network device, which is not limited in this application. The second network device is used as an example for description below.

The method includes: the second network device receives second context information of a terminal device from a core network device; the second network device receives first request information from the terminal device, the first request information is used to request access to the second network device, the first request information includes identification information of the terminal device, wherein the second network device is a non-terrestrial network device.

It should be understood that the seventh aspect corresponds to some of the implementation methods of the above-mentioned first to sixth aspects. The technical effects and related introductions can be found in the detailed introductions of the above-mentioned first to sixth aspects, and will not be repeated here.

In combination with the seventh aspect, in some possible implementations, the second network device sends first response information to the terminal device based on the second context information and the first request information of the terminal device, where the first response information includes the NCC.

In combination with the seventh aspect, in some possible implementation methods, before the second network device receives the second context information of the terminal device from the core network device, the method also includes: the second network device receives the first request information from the terminal device; the second network device sends the second request information to the core network device based on the first request information, and the second request information is used to request to obtain the second context information of the terminal device, and the second request information includes the identification information of the terminal device.

In combination with the seventh aspect, in some possible implementation methods, the NCC in the second context information of the terminal device comes from the first context information of the terminal device, or the NCC is determined by the core network device, wherein the first context information of the terminal device comes from the first network device, and the first network device is a network device that provides services to the terminal device before the second network device receives the first request information from the terminal device, and the first network device is a non-terrestrial network device.

In combination with the seventh aspect, in some possible implementation methods, when the first context information of the terminal device does not include NCC, the first context information of the terminal device includes second indication information, and the second indication information is used to instruct the core network device to configure NCC and next hop NH for the terminal device.

In combination with the seventh aspect, in some possible implementation methods, when the terminal device successfully accesses the second network device, the method also includes: the second network device sends a third indication information to the core network device, the third indication information is used to indicate that the terminal device has successfully accessed the second network device, and the third indication information includes identification information of the terminal device.

In combination with the seventh aspect, in some possible implementations, the method further includes: the second network device sends indication information for indicating the available area of the second network device.

In combination with the seventh aspect, in some possible implementation methods, the identification information of the terminal device includes: the cell radio network temporary identification C-RNTI of the terminal device in the first cell, the first cell is a cell that provides services to the terminal device within the coverage of the first network device; the identification information of the terminal device also includes one or more of the following: the physical cell identification PCI of the first cell, the location information of the terminal device, the identification information of the first network device, or the identification information of the first cell.

In combination with the seventh aspect, in some possible implementation methods, the first request information is radio resource control (RRC) re-establishment request information or RRC connection recovery request information; when the first request information is RRC re-establishment request information, the first request information includes the RRC re-establishment reason; when the first request information is RRC connection recovery request information, the first request information includes the RRC connection recovery reason.

In combination with the seventh aspect, in some possible implementation methods, when the first request information includes the RRC re-establishment reason, the first request information includes a first cause value, and the first cause value is otherfailure; when the first request information includes the RRC connection recovery reason, the first request information includes a second cause value, and the second cause value is delayTolerantAccess-v1020.

In an eighth aspect, a communication method is provided, the method comprising: a second network device sends a first message, the first message comprising a first information element, the first information element being used to indicate whether a first type of terminal device is allowed to access the second network device, the first type of terminal device comprising a store-and-forward terminal device; the second network device receives a first request message from a terminal device, the first request message being used to request access to the second network device, the terminal device being the first type of terminal device, wherein the second network device is a non-terrestrial network device.

It should be understood that the method is exemplarily introduced with the second network device as the execution subject. Of course, other network devices in the at least one third network device (such as the third network device) are also applicable to the method provided in this application.

It should also be understood that the first information element may be referred to as an sfBarred information element. The first message may be a system message, for example, the first message may be a master information block (MIB) or a system information block (SIB), etc., which is not limited in this application.

It should also be understood that the first category of terminal devices includes store-and-forward terminal devices, or can be referred to as terminal devices supporting S&F functions, or can be referred to as terminal devices capable of accessing S&F network devices.

It should also be understood that whether the second network device operates in the S&F mode may vary.

In one possible implementation, when the second network device is in S&F mode (or referred to as the second network device operating in S&F mode, or referred to as the second network device being an S&F network device), the first information element is used to indicate that a first-category terminal device is allowed to access the second network device. Thus, the second network device indicates access to a terminal device supporting the S&F function through the first information element in the first message, thereby ensuring that the terminal device supporting the S&F function can access the S&F network device.

In another possible implementation, the second network device is in a non-S&F mode (or referred to as the second network device operating in the non-S&F mode, or referred to as the second network device being a non-S&F network device), and the first information element is used to indicate that the first type of terminal device is not allowed/rejected from accessing the second network device. The second network device, through the first information element in the first message, indicates that the terminal device supporting the S&F function is refusal to access the second network device, thereby preventing the terminal device supporting the S&F function from requesting access to the second network device, thereby saving resource overhead of the terminal device.

In combination with the eighth aspect, in some possible implementations, the second network device is in the S&F mode, the first information element is a first value, and the first information element is used to indicate that the first type of terminal device is allowed to access the second network device.

As an example, the first value may be “not barred”. When the first information element (sfBarred information element) is “not barred”, the sfBarred information element is used to indicate that the first type of terminal device is allowed to access the second network device.

In combination with the eighth aspect, in some possible implementations, the second network device is in a non-S&F mode, the first information element is a non-first value, and the first information element is used to indicate that the first type of terminal device is denied access to the second network device.

As an example, the non-first value may be “barred.” When the first information element (sfBarred information element) is “barred,” the sfBarred information element is used to indicate that the first type of terminal device is denied access to the second network device.

It should be understood that the specific values of the first value and the non-first value described above are merely examples, and the first value and the non-first value may also be indicated by other symbols, numbers, or letters, or by one or more combinations thereof, and this application is not limited thereto. For example, whether the second network device allows the first type of terminal device to access may be indicated by a bit value or binary format, and this application will not elaborate on these details.

In combination with the eighth aspect, in some possible implementations, the first message also includes a second information element and/or a third information element, the second information element is used to indicate whether the second type of terminal device is allowed to access the second network device, and the third information element is used to indicate whether the third type of terminal device is allowed to access the second network device, wherein the second type of terminal device includes a ground network terminal device, and the third type of terminal device includes a non-ground network terminal device.

It should be understood that terrestrial network terminal equipment is also called normal terminal equipment, and non-terrestrial network terminal equipment is also called NTN terminal equipment, or terminal equipment that supports services provided by NTN, or terminal equipment capable of receiving NTN services.

It should also be understood that the second information element may be a cellBarred information element in a system message, and the third information element may be a cellBarredNTN information element in a system message, which is not limited in this application.

In combination with the eighth aspect, in some possible implementations, the second network device is in the S&F mode, the second information element is a second value, and the second information element is used to indicate that the second type of terminal device is denied access to the second network device; the third information element is a third value, and the third information element is used to indicate that the third type of terminal device is denied access to the second network device.

It should be understood that the specific expressions of the second value and the third value are similar to those of the first value, and are not limited in this application. For example, the second value may be "barred" and the third value may be "barred".

Based on the above solution, when the second network device is in the S&F mode, the second information element and the third information element in the first message of the second network device are used to indicate that the second type of terminal devices and the third type of terminal devices are denied access to the second network device, thereby preventing non-S&F terminal devices from accessing the second network device and ensuring that the S&F network device only provides services for terminal devices that support the S&F function.

In combination with the eighth aspect, in some possible implementations, when the second network device is in non-S&F mode, the second information element is a second value, and the second information element is used to indicate that the second type of terminal device is denied access to the second network device; the third information element is a non-third value, and the third information element is used to indicate that the third type of terminal device is allowed to access the second network device.

It should be understood that a non-third value is different from a third value, and the specific form of the non-third value is not limited in this application. For example, a non-second value may be "not barred" and a non-third value may be "not barred".

[Corrected 12.03.2025 in accordance with Article 91]
It should be understood that the second network device is a non-terrestrial network device, that is, the second information element of the second network device is the second value in the non-S&F mode or in the S&F mode.

Based on the above solution, when the second network device is in non-S&F mode, the first information element in the first message of the second network device is used to indicate that the first type of terminal device is denied access to the second network device, the second information element is used to indicate that the second type of terminal device is denied access to the second network device, and the third information element is used to indicate that the third type of terminal device is allowed access to the second network device. When the second network device is not in S&F mode, it allows non-terrestrial network terminal devices to access the second network device and denies access to terminal devices that support the S&F function, ensuring that terminal devices that support the S&F function can only access network devices in S&F operating mode.

In a ninth aspect, a communication method is provided, the method comprising: a terminal device receives a first message, the first message comprising a first information element, the first information element being used to indicate whether a first type of terminal device is allowed to access a second network device, the first type of terminal device comprising a store-and-forward terminal device; when the first information element is used to indicate that the first type of terminal device is allowed to access a second network device, and the terminal device is the first type of terminal device, the terminal device sends a first request message to the second network device, the first request message being used to request access to the second network device, wherein the second network device is a non-terrestrial network device.

It should be understood that the relevant descriptions and technical effects of the ninth aspect are similar to those of the eighth aspect mentioned above and will not be repeated here.

In combination with the ninth aspect, in some possible implementations, the second network device is in the S&F mode, the first information element is a first value, and the first information element is used to indicate that the first type of terminal device is allowed to access the second network device.

In combination with the ninth aspect, in some possible implementations, the second network device is in a non-S&F mode, the first information element is a non-first value, and the first information element is used to indicate that the first type of terminal device is denied access to the second network device.

In combination with the ninth aspect, in some possible implementations, the first message also includes a second information element and/or a third information element, the second information element is used to indicate whether the second type of terminal device is allowed to access the second network device, and the third information element is used to indicate whether the third type of terminal device is allowed to access the second network device, wherein the second type of terminal device includes a ground network terminal device, and the third type of terminal device includes a non-ground network terminal device.

In conjunction with the ninth aspect, in some possible implementations, the first message further includes the second information element and the third information element. If the terminal device is not a terminal device of the first category but is a terminal device of the third category, the terminal device ignores the first information element and the second information element, and the terminal device determines whether to send the first request information to the second network device based on the third information element. If the terminal is not a terminal device of the first category but is a terminal device of the second category, the terminal device ignores the first information element and the third information element, and the terminal device determines whether to send the first request information to the second network device based on the second information element.

In combination with the ninth aspect, in some possible implementations, the second network device is in the S&F mode, the second information element is a second value, and the second information element is used to indicate that the second type of terminal device is denied access to the second network device; the third information is a third value, and the third information element is used to indicate that the third type of terminal device is denied access to the second network device.

In combination with the ninth aspect, in some possible implementations, when the second network device is in non-S&F mode, the second information element is a second value, and the second information element is used to indicate that the second type of terminal device is denied access to the second network device; the third information element is a non-third value, and the third information element is used to indicate that the third type of terminal device is allowed to access the second network device.

In one possible implementation, assuming that the terminal device is not a first-category terminal device but a third-category terminal device, the terminal device may ignore the values of the first information element and the second information element. When the third information element is a non-third value, the terminal device determines to send the first request information to the second network device based on the value of the third information element. assuming that the terminal device is not a first-category terminal device but a second-category terminal device, the terminal device may ignore the values of the first information element and the third information element. It should be understood that if the second network device is a non-terrestrial network device and the second information element is the second value, the terminal device determines not to send the first request information to the second network device.

In a tenth aspect, a communication device is provided, comprising a transceiver unit and a processing unit. When a terminal device leaves the coverage of a first network device providing services for the terminal device, the processing unit is configured to change the state of the communication device from a connected state to a first state, where the first state includes any one of the following: a connected state suspended by an access layer (AS) of the terminal device, a suspended idle state, or an inactive state; and the transceiver unit is configured to send a first request message to a second network device, where the first request message is used to request access to the second network device, and the first request message includes identification information of the terminal device, wherein the first network device and the second network device are non-terrestrial network devices.

It should be understood that the transceiver unit is also used to perform the receiving and sending processing in the first aspect. The processing unit can perform other processing in addition to the receiving and sending in the first aspect.

In an eleventh aspect, a communication device is provided, comprising a transceiver unit. The transceiver unit is configured to send first indication information to a terminal device, the first indication information being used to instruct the terminal device to access the first network device when the terminal device leaves and then re-enters the coverage range of the first network device; and the transceiver unit is further configured to receive first request information from the terminal device, the first request information being used to request access to the first network device, wherein the first network device is a non-terrestrial network device.

It should be understood that the transceiver unit is also used to perform the receiving and sending processing as in the second aspect above.

In a twelfth aspect, a communication device is provided, comprising a transceiver unit. The transceiver unit is configured to send first information to a terminal device, the first information including at least one third network device and indication information of an available area of each of the at least one third network device, the at least one third network device including a second network device and/or the first network device, and each of the at least one third network device being a non-terrestrial network device.

It should be understood that the transceiver unit is also used to perform the receiving and sending processing as in the third aspect above.

In a thirteenth aspect, a communication device is provided, comprising a transceiver unit. The transceiver unit is configured to send first information to a terminal device, the first information including at least one third network device, the at least one third network device including a first network device and a second network device, the first information further including indication information indicating an available area of the first network device, and each of the at least one third network device being a non-terrestrial network device.

It should be understood that the transceiver unit is also used to perform the receiving and sending processing as in the fourth aspect above.

In a fourteenth aspect, a communication device is provided, comprising a transceiver unit. The transceiver unit is configured to send first information to a terminal device, wherein the first information includes at least one third network device; and the transceiver unit is further configured to send second information to a core network device, wherein the second information includes first context information of the terminal device, and the first context information of the terminal device includes identification information of the terminal device, wherein the first network device and the at least one third network device are non-terrestrial network devices, and when the first network device has an unused next hop NH, the first context information of the terminal device further includes: a key and a next hop chain calculation NCC, wherein the key is determined by the first network device based on the NH, or, when the first network device does not have the unused NH, the first context information of the terminal device further includes: second indication information, wherein the second indication information is used to instruct the core network device to determine the NH and the NCC.

It should be understood that the transceiver unit is also used to perform the receiving and sending processing as in the fifth aspect above.

In one possible implementation, the communication device further includes a processing unit, which can perform other processing in addition to receiving and sending in the aforementioned fifth aspect.

In a fifteenth aspect, a communication device is provided, comprising a transceiver unit. The transceiver unit is configured to receive second information from a first network device, the second information comprising first context information of a terminal device, the first context information of the terminal device comprising identification information of the terminal device; and the transceiver unit is further configured to send the second context information of the terminal device to at least one third network device, the second context information of the terminal device comprising a key and the NCC, or the second context information of the terminal device comprising the NCC and a next hop (NH), wherein the key is determined based on the NH, and the first network device and the at least one third network device are non-terrestrial network devices.

It should be understood that the transceiver unit is also used to perform the receiving and sending processing as in the sixth aspect above.

In one possible implementation, the communication device further includes a processing unit, which can perform other processing in addition to receiving and sending in the aforementioned sixth aspect.

In a sixteenth aspect, a communication device is provided, comprising a transceiver unit configured to receive second context information of a terminal device from a core network device; and a transceiver unit configured to receive first request information from the terminal device, the first request information being used to request access to the second network device, the first request information including identification information of the terminal device, wherein the second network device is a non-terrestrial network device.

It should be understood that the transceiver unit is also used to perform the receiving and sending processing as in the seventh aspect above.

In one possible implementation, the communication device further includes a processing unit that can perform other processing in addition to receiving and sending in the aforementioned seventh aspect.

In a seventeenth aspect, a communication device is provided, comprising a transceiver unit. The transceiver unit is configured to send a first message, the first message comprising a first information element, the first information element being configured to indicate whether a first-category terminal device is allowed to access the second-network device, the first-category terminal device comprising a store-and-forward terminal device; and the transceiver unit is further configured to receive a first request message from a terminal device, the first request message being configured to request access to the second-network device, the terminal device being the first-category terminal device, and the second-network device being a non-terrestrial network device.

It should be understood that the transceiver unit is also used to perform the receiving and sending processing as in the eighth aspect above.

In one possible implementation, the communication device further includes a processing unit that can perform other processing in addition to receiving and sending in the aforementioned eighth aspect.

In an eighteenth aspect, a communication device is provided, comprising a transceiver unit. The transceiver unit is configured to receive a first message, the first message comprising a first information element, the first information element being configured to indicate whether a first-category terminal device is allowed to access a second-network device, the first-category terminal device comprising a store-and-forward terminal device; and the transceiver unit is further configured to send a first request message to the second-network device, the first request message being configured to request access to the second-network device, the terminal device being the first-category terminal device, wherein the second-network device is a non-terrestrial network device.

It should be understood that the transceiver unit is also used to perform the receiving and sending processing as in the ninth aspect above.

In one possible implementation, the communication device further includes a processing unit that can perform other processing in addition to receiving and sending in the aforementioned ninth aspect.

In the nineteenth aspect, an embodiment of the present application provides a communication device. The communication device may be a device or apparatus with a chip, or a device or apparatus integrated with a circuit, or a chip, a chip system, a module or a control unit in the aforementioned device or apparatus, and the specific application is not limited thereto. It should be noted that, in the present application, when referring to a communication device, it may refer to the communication device itself, or to a chip, a functional module or an integrated circuit in the communication device that completes the method provided in the present application, and the specific application is not limited thereto. The device is used to execute the methods provided in the first to ninth aspects above. Specifically, the device may include units and/or modules for executing the method provided in any one of the implementations in the first to ninth aspects, such as a transceiver unit (or transceiver module) and a processing unit (or processing module).

In some implementations, the processing unit may be at least one processor. The transceiver unit may be a transceiver or an input/output interface. Alternatively, the transceiver may be a transceiver circuit. Alternatively, the input/output interface may be an input/output circuit.

In some implementations, the communication device is a chip, chip system, or circuit in a terminal device or network device. The transceiver module can be an input/output interface, interface circuit, output circuit, input circuit, pin, or related circuit on the chip, chip system, or circuit. The processing unit can be at least one processor, processing circuit, or logic circuit.

In a twentieth aspect, an embodiment of the present application provides a processor for executing the methods provided in the above aspects. For operations such as sending and receiving involved in the processor, unless otherwise specified, or unless they conflict with their actual functions or inherent logic in the relevant description, they can be understood as processor output, reception, input, and other operations, and can also be understood as sending and receiving operations performed by the radio frequency circuit and antenna, and this application does not limit this.

In aspect 21, an embodiment of the present application provides a communication system, which includes a terminal device and a network device. The terminal device can execute the method provided by any one of the implementation methods of the above-mentioned first aspect and ninth aspect; the network device can execute the method provided by any one of the implementation methods of the above-mentioned second aspect, third aspect, fourth aspect, sixth aspect, and seventh aspect.

In one possible implementation, the communication system further includes a core network device, which can execute the method provided in any one of the implementations of the fifth aspect above.

In a twenty-second aspect, an embodiment of the present application provides a computer-readable storage medium. The computer-readable storage medium stores instructions or program codes, which, when executed by a processor, can implement the method provided in any one of the implementations of aspects 1 to 9 above.

In a twenty-third aspect, an embodiment of the present application provides a computer program product comprising instructions. When the computer program product is run on a computer, the computer is caused to execute the method provided in any one of the implementations of the first to ninth aspects above.

In a twenty-fourth aspect, an embodiment of the present application provides a chip. The chip includes a processor and a communication interface, wherein the processor reads instructions stored in a memory through the communication interface and executes the method provided in any one of the implementation modes of the first to ninth aspects above.

Optionally, as an implementation method, the chip also includes a memory, in which a computer program or instruction is stored, and the processor is used to execute the computer program or instruction stored in the memory. When the computer program or instruction is executed, the processor is used to execute the method provided in any one of the implementation methods of the first to ninth aspects above.

The beneficial effects brought about by the third to sixteenth aspects mentioned above can be specifically referred to the description of the beneficial effects in the first or second aspect, and will not be repeated here.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a communication system used in an embodiment of the present application.

FIG2 is a schematic diagram of the network architecture provided in an embodiment of the present application.

FIG3 is a schematic diagram of a KeNB update method.

FIG4 is a schematic diagram of an S&F scenario.

FIG5 is a flow chart of a communication method provided in an embodiment of the present application.

FIG6 is a flow chart of another communication method provided in an embodiment of the present application.

FIG7 is a flow chart of another communication method provided in an embodiment of the present application.

FIG8 is a flow chart of another communication method provided in an embodiment of the present application.

FIG9 is a schematic diagram of a communication device provided in an embodiment of the present application.

FIG10 is another schematic diagram of a communication device provided in an embodiment of the present application.

FIG11 is a schematic diagram of a chip system provided in an embodiment of the present application.

DETAILED DESCRIPTION

The technical solution in this application will be described below with reference to the accompanying drawings.

For ease of understanding, the communication system shown in FIG1 is used as an example to describe the communication system applicable to each embodiment of the present application.

As shown in Figure 1 , the communications system includes a radio access network (RAN) 100 and a core network (CN) 200. RAN 100 includes at least one RAN node (e.g., 110a and 110b in Figure 1 , collectively referred to as 110) and at least one terminal device (e.g., 120a-120j in Figure 1 , collectively referred to as 120). The RAN may also include other RAN nodes, such as wireless relay devices and/or wireless backhaul devices (not shown in Figure 1 ). Terminal device 120 is wirelessly connected to RAN node 110. RAN node 110 is wirelessly or wiredly connected to core network 200. The core network devices in core network 200 and RAN node 110 in RAN 100 can be separate physical devices, or they can be the same physical device that integrates core network logical functions and radio access network logical functions.

The RAN 100 can be a cellular system related to the Third Generation Partnership Project (3GPP), such as a 4G, 5G, or 6G mobile communication system, a non-terrestrial network (NTN) system, or a future-oriented evolutionary system. The RAN 100 can also be an open access network (O-RAN or ORAN), a cloud radio access network (CRAN), or a wireless fidelity (WiFi) system, or a communication system that integrates two or more of the above systems.

In a communication system, a device can send signals to or receive signals from another device. Signals can include information, signaling, or data. Devices can also be replaced by entities, network entities, communication devices, communication modules, nodes, communication nodes, etc. The embodiments of this application are described using devices as an example.

In the embodiments of the present application, the terminal device is a device with wireless transceiver functions, which may refer to user equipment (UE), access terminal, subscriber unit, user station, mobile station, remote station, remote terminal, mobile device, user terminal, wireless communication equipment, user agent or user device.

In the embodiment of the present application, the terminal device may also be a satellite phone, a cellular phone, a smart phone, a wireless data card, a wireless modem, a machine type communication device, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a customer-premises equipment (CPE), a smart point of sale (POS) machine, a handheld device with wireless communication capabilities, a computing device or other processing device connected to a wireless modem, a vehicle-mounted device, a communication device carried on a high-altitude aircraft, a wearable device, a drone, a robot, a terminal in device-to-device (D2D) communication, a vehicle-to-everything (V2D) communication, or a vehicle-to-everything (V2P) communication. In the embodiment of the present application, the device for realizing the function of the terminal device may be a terminal device, or a device that can support the terminal device to realize the function, such as a chip system or a chip, which can be installed in the terminal device. In the embodiment of the present application, the chip system can be composed of a chip, or it can include a chip and other discrete devices.

In the embodiment of the present application, the terminal device may also be a device with communication functions in the 6G communication system, without limiting the form or type of the terminal device in the 6G and other future communication systems.

In the embodiments of the present application, the RAN node 110 may also be referred to as an access network device, an access node, or a RAN entity, and is used to help terminal devices achieve wireless access. Multiple RAN nodes 110 may be nodes of the same type or different types. In some scenarios, the roles of the RAN node 110 and the terminal device 120 are relative. For example, the network element 120i in Figure 1 may be a helicopter or a drone, which can be configured as a mobile base station. For the terminal 120j that accesses the RAN 100 through the network element 120i, the network element 120i is a base station; but for the base station 110a, the network element 120i is a terminal device. The RAN node 110 and the terminal device 120 are sometimes referred to as communication devices. For example, the network elements 110a and 110b in Figure 1 can be understood as communication devices with base station functions, and the network elements 120a-120j can be understood as communication devices with terminal functions.

In one possible scenario, the RAN node 110 can also be a network device, such as a base station, an evolved NodeB (eNodeB), an access point (AP), a transmission reception point (TRP), a next-generation NodeB (gNB), a next-generation base station in a 6G mobile communication system, a base station in a future mobile communication system, or an access node in a WiFi system. A RAN node can be a macro base station (such as 110a in Figure 1 ), a micro base station or an indoor station (such as 110b in Figure 1 ), a relay node or a donor node, or a wireless controller in a CRAN scenario. Alternatively, a RAN node can be a server, a wearable device, a vehicle, or an onboard device. For example, a network device in vehicle-to-everything (V2X) technology can be a roadside unit (RSU).

In another possible scenario, multiple RAN nodes collaborate to assist terminals in achieving wireless access, with different RAN nodes implementing portions of the base station's functionality. For example, a RAN node can be a centralized unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU). The CU and DU can be separate or included in the same network element, such as the baseband unit (BBU). The CU and DU nodes split the gNB's protocol layers, centrally controlling some protocol layer functions within the CU and distributing some or all of the remaining protocol layer functions within the DU, which is then centrally controlled by the CU. As an implementation, the CU is deployed with the radio resource control (RRC), packet data convergence protocol (PDCP), and service data adaptation protocol (SDAP) layers of the protocol stack; the DU is deployed with the radio link control (RLC), media access control (MAC), and physical layer (PHY) layers of the protocol stack. Thus, the CU has the processing capabilities of RRC, PDCP, and SDAP, while the DU has the processing capabilities of RLC, MAC, and PHY. It should be understood that the above functional division is merely an example and does not constitute a limitation on the CU and DU. The RU may be included in a radio frequency device or radio unit, such as a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).

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

Optionally, for network elements in the ORAN system, each network element may implement the protocol layer functions shown in Table 1 below.

Table 1

It should be noted that, in the ORAN system, the network device in this application may be one or more network elements in Table 1 above.

In the embodiment of the present application, the core network device 200 refers to a device in the core network (CN) that provides service support for the terminal device 120. At present, some examples of core network devices are: access and mobility management function (AMF) entity, session management function (SMF) entity, user plane function (UPF) entity, etc., which are not listed here one by one. Among them, the AMF entity can be responsible for access management and mobility management of terminal devices; the SMF entity can be responsible for session management, such as user session establishment, etc.; the UPF entity can be a functional entity of the user plane, mainly responsible for connecting to the external network. It should be noted that in this application, the entity can also be referred to as a network element or a functional entity. For example, the AMF entity can also be referred to as an AMF network element or an AMF functional entity. For another example, the SMF entity can also be referred to as an SMF network element or an SMF functional entity, etc.

In the embodiments of the present application, the device for implementing the functions of the network device can be a network device; it can also be a device that can support the network device to implement the functions, such as a chip system, a hardware circuit, a software module, or a hardware circuit and a software module. The device can be installed in the network device or used in conjunction with the network device. In the embodiments of the present application, only the device for implementing the functions of the network device is used as an example to illustrate, and does not constitute a limitation on the solutions of the embodiments of the present application.

It should be noted that the embodiments of the present application do not limit the scenarios in which the network device/terminal device is located. In addition, the network device/terminal device can be a hardware device, or a software function running on dedicated hardware, or a software function running on general-purpose hardware. For example, it can be an entity including dedicated or general-purpose hardware devices and software functions. The present application does not limit the specific form of the network device/terminal device.

The following is an illustrative introduction to the scenario architecture, technical terms, and communication methods involved in the method of this application.

First, the architecture applicable to the method provided in the embodiment of the present application will be exemplarily introduced in conjunction with the architecture diagram shown in Figure 2. Of course, the architecture shown in Figure 2 is only an example, and those skilled in the art can combine or improve the architecture provided in the present application, which is also applicable to the method provided in the present application.

FIG2 is a schematic diagram of the network architecture provided in an embodiment of the present application.

Architecture 1: As shown in (1) in Figure 2, in the transparent satellite scenario, the satellite's functions are: wireless frequency filtering, frequency conversion, and amplification. The transparent satellite acts as an L1 relay, regenerating the physical layer signal and does not have other higher protocol layers. The satellite communicates with the ground NTN gateway via wireless signals, and the gateway is connected to the gNB via a wired connection. In this architecture, the satellite can be understood as the remote radio unit of the ground base station (gNB). The satellite only provides simple physical signal coverage, and the remote radio function needs to pass through the gateway and the microwave link between the satellite and the gateway to reach the satellite. During the transmission process, no protocol layer processing is performed, and no logical interface is established.

Architecture 2: As shown in (2) of FIG2 , in a regenerative satellite scenario, the regenerative satellite has the processing function of a base station and can perform related processing operations such as storage and forwarding on forwarded data.

Architecture 3: As shown in (3) of Figure 2, in a regenerative satellite scenario with inter-satellite links, the satellite is connected to other satellites via inter-satellite links. In a scenario where the local satellite is not visible to the ground gateway, the local satellite can transmit its data to other satellites via inter-satellite links (ISLs), which are then forwarded to the ground gateway.

In this architecture, the satellite acts as a base station, performing all of its protocol layer processing functions. Satellites transmit data back to ground gateways via microwaves, which are then connected to the 5G core network via wired connections. In the regenerative satellite scenario, the link between the base station and gateway is generally referred to as the satellite radio interface (SRI).

Architecture 4: As shown in (4) in Figure 2, in the scenario of a regenerative satellite with DU processing capabilities of a base station, the satellite acts as a gNB-DU and connects to the gNB-CU on the ground through a ground gateway.

Architecture 5: In a satellite scenario with integrated access and backhaul (IAB) functionality, the satellite acts as an IAB node, similar to Architecture 4. However, in Architecture 5, in addition to the DU, a mobile terminal (MT) module is also deployed on the satellite. Backhaul is performed using the air interface between the MT and the ground base station, eliminating the need to establish a separate microwave backhaul link between the satellite and the gateway.

Secondly, the security mechanism of the access layer (AS) of the terminal device is briefly introduced.

Data transmission between the UE and gNB requires encryption and integrity protection, and different keys are used for different messages. For example, the keys required for data transmission between the UE and gNB include Krrcint (for RRC signaling integrity protection), Krrcenc (for RRC signaling encryption), and Kupenc (for user plane encryption). These keys are all derived from KeNB, so the KeNB values must be aligned between the UE and gNB to ensure secure data transmission between the UE and gNB. The following sections focus on 1) how KeNB is obtained during the UE's initial network access, 2) how KeNB is updated during handover scenarios, and 3) how KeNB is updated during RRC recovery or RRC re-establishment scenarios.

1) Acquisition of KeNB in the initial access scenario

When the UE initially accesses, the UE and the core network device will each derive KeNB based on the root key Kasme. In the embodiment of the present application, the core network device is introduced by taking the mobility management entity (MME) as an example. Among them, Kasme is derived from the upper-level root key. The root key Kasme used by the UE and the MME to derive KeNB must be the same. For details, please refer to the introduction in the prior art and will not be explained in detail here. The UE obtains KeNB by calculating it based on Kasme. The base station side obtains KeNB after the UE establishes an RRC connection with the base station. The base station sends an INITIAL UE MESSAGE to the MME, and the core network performs user authentication (or authentication). If the core network successfully authenticates the UE, the MME will derive KeNB and inform the base station through the INITIAL CONTEXT SETUP REQUEST message. At this point, both the UE and the base station have obtained the value of KeNB. Next, the base station informs the UE of the encryption algorithm through the SMC process (Security Mode Command message, etc.) and establishes a secure connection with the UE.

It should be understood that in the initial access process of the UE, based on the above introduction, before the SMC process, the communication between the UE and the base station is not encrypted, and after the SMC, the communication between the UE and the base station is encrypted.

2) Update of KeNB in switching scenarios

Handover scenarios include: intra-UE handover (the UE's serving cell is updated, but the base station does not change), inter-UE X2 handover, and inter-UE S1 handover. Intra-UE handover refers to a change in the UE's serving cell, for example, the cell serving the UE changes from a source serving cell to a target serving cell, and the source and target serving cells correspond to the same base station. Inter-UE X2 handover refers to a change in the base station serving the UE, meaning that an X2 handover refers to a switch in the interface between the two base stations. Inter-UE S1 handover refers to a change in the interface between the base station serving the UE and the MME.

Among them, in the scenario of UE intra-site handover, the PCI of the target cell serving the UE, the frequency of the target cell, and the KeNB or NH before the update are used to determine the updated KeNB. For the above-mentioned UE intra-site handover, since the UE's serving cell has changed, that is, the PCI and frequency of the target serving cell are different from the PCI and frequency of the source serving cell, that is, after the UE switches to the target serving cell, it is necessary to use the updated KeNB for secure communication with the target serving cell.

In the scenarios of inter-UE X2 handover and inter-UE S1 handover, the UE also needs to update the KeNB.

It should be understood that the update mode of KeNB is divided into horizontal derivation and vertical derivation, as shown in Figure 3. The following takes UE inter-station X2 handover and UE inter-station S1 handover as examples to introduce the key KeNB update process.

Figure 3 is a schematic diagram of the KeNB update method, where KeNB* represents the updated KeNB. The calculation of KeNB* requires three input parameters: the PCI of the target serving cell, the frequency of the target serving cell, and the KeNB or NH before the update.

In the scenario of inter-UE X2 handover, the source base station determines the PCI and frequency of the target cell based on the potential target cell selected for the UE, and then determines the third parameter (KeNB or NH before the update) based on the following principles to obtain KeNB*. Specifically, the principle for the source base station to determine the third parameter includes: the source base station determines whether the source base station has unused {NH, NCC} locally. If so, the third parameter used to determine KeNB* uses NH. The process of generating KeNB* at this time is called vertical derivation. If not, the third parameter used to determine KeNB* uses KeNB before the update. The process of generating KeNB* at this time is called horizontal derivation.

It should be understood that based on the above-mentioned method for determining KeNB*, vertical derivation is generally used because it is more secure than horizontal derivation. When the source base station has no unused {NH, NCC} locally, the source base station uses horizontal derivation to determine KeNB*.

It should also be understood that the next hop (NH) can be understood as the starting point value for KeNB* derivation, and the next hop chaining count (NCC) can be understood as the NH and the number of KeNBs subsequently derived horizontally based on the NH, as shown in Figure 3. After the source base station determines KeNB* through vertical or horizontal derivation, it will carry KeNB* and the NCC corresponding to the third parameter in a handover request message and send it to the target base station. In response, the target base station obtains KeNB* from the source base station. KeNB* is the new key that the target base station will subsequently use with the UE. At the same time, the target base station can forward the NCC received from the source base station to the UE, and the UE further determines KeNB* based on the received NCC.

The UE can derive KeNB* from the NCC, the PCI of the target cell, and the frequency of the target cell carried in the handover command sent by the target base station to the UE. For example, the UE can determine whether the NCC in the handover command is the same as the NCC currently used by the UE. If they are the same, this means that the derivation is horizontal, and the UE will perform a horizontal derivation (or horizontal derivation) based on the old KeNB, the PCI of the target cell, and the frequency of the target cell carried in the handover command to obtain KeNB*. If they are different, this means that the derivation is vertical, and the NH is newly designated. The UE will first derive vertically hop by hop to the NH corresponding to the current NCC (wherein the NCC corresponding to the NH is not necessarily the UE's current NCC+1, because there are unused {NH, NCC} in the source base station, which may not necessarily be the NCC+1 corresponding to the UE. Therefore, multiple hop-by-hop derivations may be required to obtain the NH). The UE then obtains KeNB* based on the NH and the PCI of the target cell and the frequency of the target cell carried in the handover command.

It should be understood that based on the above introduction, both the target base station and the UE have obtained KeNB*. After the UE switches, the target base station will send a PATH SWITCH REQUEST message to the core network MME to inform the core network that the UE has switched to the target base station. The MME will maintain the NCC number corresponding to the target base station, and then in the PATH SWITCH REQUEST ACK message, add 1 to this NCC to calculate a new NH, and send the calculated {NH, NCC} to the target base station as a supplement for the subsequent determination of KeNB*. After receiving this {NH, NCC}, the target base station stores it locally as unused {NH, NCC} for the next switch, and deletes other unused {NH, NCC}. In other words, each time the target base station accepts a switched UE, the core network will allocate a new {NH, NCC} to it as unused {NH, NCC} for the target base station to use with the switched UE next time. The UE is not necessarily the UE that has just switched as mentioned above, and any UE can be used. This application does not limit it.

The above describes key updates during X2 handovers for UE inter-station handovers. It can be seen that in X2 handovers, the source base station is responsible for generating the new KeNB*. However, in S1 handovers, due to the MME's involvement, new key derivation is not performed by the source base station but rather by the MME and the target base station. For example, the source base station sends a HANDOVER REQUIRED message to the MME, which does not carry any KeNB* or NCC information. The MME then adds 1 to the NCC of the target base station maintained at the MME to obtain a new NH. The MME then sends this {NH, NCC}, along with the PCI and frequency of the target cell, to the target base station via a HANDOVER REQUEST message. The target base station determines KeNB* based on these three parameters in the message from the MME. Inter-site S1 handover is similar to inter-site X2 handover. The target base station sends the NCC, PCI of the target cell, and frequency of the target cell to the UE via a handover command through the MME and the source base station. The UE determines whether to use horizontal or vertical derivation based on the NCC to determine KeNB*. This is similar to the above-mentioned inter-site X2 handover. For details, see the detailed description of inter-site X2 handover.

It should be understood that after the inter-site S1 handover, the core network does not send {NH, NCC} to the target station as a supplement. That is, the core network informs the target base station in the HANDOVER REQUEST that {NH, NCC} is used for this UE handover. In the inter-site X2 handover scenario, the core network informs the target base station in the PATH SWITCH REQUEST ACK that {NH, NCC} is used for subsequent handovers.

In summary, in inter-station X2 handover, KeNB* may be determined by vertical derivation or horizontal derivation; while in inter-station S1 handover, KeNB* is determined by vertical derivation.

3) KeNB update during RRC connection reestablishment or RRC connection resume

When a connected UE detects a failure in the radio link connection with the current base station, it selects a new base station to initiate the RRC Connection Reestablishment process. For UEs in the RRC idle state (IDLE with suspended), RRC connected state (connection), or RRC inactive state (RRC_INACTIVE), KeNB* derivation and update are also required in RRC reestablishment and RRC recovery scenarios. The following describes how to determine KeNB* updates in RRC reestablishment and RRC recovery scenarios.

In both scenarios, the first RRC message transmitted by the UE when accessing a new base station (e.g., RRC connection reestablishment request/RRC connection resume request) is unencrypted and carries the value of shortMAC-I. This ShortMAC-I is used to verify the legitimacy of the UE. It is calculated based on the Krrcint key using three input parameters: the UE's source cell identifier (C-RNTI), the source cell's PCI, and the target cell's cell ID. The MAC-I is then truncated (note that these three parameters are different from the three parameters used to calculate KeNB*).

For the re-establishment scenario, the UE reports its shortMAC-I used by the source base station, as well as the C-RNTI and source cell PCI of the source base station in the RRC connection reestablishment request message. The target base station determines the source base station identifier based on the source cell PCI, and puts this information together with the cell ID of the target cell in a RETRIEVE UE CONTEXT REQUEST message, which is then sent to the source base station. The source base station verifies whether the ShortMAC-I carried in the RETRIEVE UE CONTEXT REQUEST is consistent with the ShortMAC-I calculated based on the UE's C-RNTI in the source cell, the source cell PCI, and the target cell ID. If they are consistent, the UE is confirmed to be legitimate and has been served by the source cell. The source base station sends the KeNB* and NCC determined by the source base station to the target base station in the RETRIEVE UE CONTEXT RESPONSE message, and the target base station then sends the NCC to the UE via an RRC message. The method for the source base station and the UE to determine KeNB* is the same as the method for the source base station and the UE to determine KeNB* in the above inter-site X2 handover scenario. For details, please refer to the detailed introduction in the above inter-site X2 handover scenario, which is not repeated here.

For the recovery and establishment scenario, the UE carries the shortMAC-I and a resumeIdentity used by itself under the source base station in the RRC connection resume request message. The resumeIdentity includes a field representing the source base station identifier (for example, resumeIdentity = PLMN ID + gNB ID + UE ID). The target base station determines the source base station identifier based on the resumeIdentity, and puts the shortMAC-I, resumeIdentity, and the cell ID of the target cell in a RETRIEVE UE CONTEXT REQUEST message and sends it to the source base station. The source eNB determines the specific UE based on resumeIdentity. It then determines the ShortMAC-I based on the C-RNTI of the source cell where the UE resides, the PCI of the source cell, and the cell ID of the target cell. The ShortMAC-I is then compared with the ShortMAC-I in the RETRIEVE UE CONTEXT REQUEST message. If the ShortMAC-I determined by the eNB matches the ShortMAC-I in the RETRIEVE UE CONTEXT REQUEST message, the UE is confirmed to be legitimate and has been previously served by the source cell. The source eNB sends the KeNB* and NCC determined by the source eNB to the target eNB in the RETRIEVE UE CONTEXT RESPONSE message. The target eNB then sends the NCC to the UE via an RRC message. The method by which the source eNB and UE determine KeNB* is the same as that used in the inter-site X2 handover scenario described above. For details, please refer to the detailed description of the inter-site X2 handover scenario and will not be repeated here.

Next, the store and forward (S&F) scenario is introduced as an example.

In 3GPP, NTN-related topics include New Radio (NR) NTN and Internet of Things (IoT) NTN. These two technologies share a fundamentally similar architecture, with some distinct features. IoT NTN is an evolution of LTE, with the base station being the eNodeB (eNB). In Release 19, IoT NTN will research store and forward (S&F) technology based on a regenerative satellite architecture. The need for S&F arises from the limited number of satellites and ground gateways used by smaller satellite operators, making it difficult to maintain a constant connection between ground gateways and satellites.

Figure 4 is a schematic diagram of a S&F scenario. When the satellite covers a UE, it cannot connect to the gateway and communicate with the core network. When the satellite connects to the gateway and communicates with the core network, there are no UEs within the satellite's coverage area. In this scenario, normal real-time services cannot be completed. However, for some non-real-time IoT services (such as sensor data reporting), communication between the satellite and the UE can be carried out when the satellite covers the UE. When the satellite covers the gateway, communication between the satellite and the core network can be carried out in a relay manner. This is the S&F scenario currently being studied. In this S&F scenario, the satellite needs to have a certain level of storage and processing capabilities to cache data from the UE or core network and forward it when it regains coverage of the core network or UE at some point in the future. Therefore, the satellite in this S&F scenario is a regenerative satellite, for example, it can serve as an eNB.

The discontinuous coverage scenario for IoT NTNs studied in Release 18 primarily involves a period of time after the previous satellite departs before the next satellite reaches the UE. In Release 18, the coverage between the satellite and the ground gateway is continuous, meaning the satellite is always connected to the ground gateway. These satellites are transparent transmission satellites, unlike the regenerative satellites used in the S&F scenario. Clearly, Release 18 does not account for discontinuous coverage between the satellite and the ground gateway.

Considering the S&F scenario, the satellite has discontinuous coverage relative to the ground gateway and the UE. The UE cannot align the KeNB value with the base station, resulting in the inability to establish a secure connection between the UE and the base station, and the inability to communicate normally between the UE and the network.

Based on the above technical problems, the present application provides a communication method, which can ensure normal communication between UE and network in S&F scenarios.

FIG5 is a flow chart of a communication method provided in an embodiment of the present application.

It should be understood that in the method shown in Figure 5, taking network device 1 as the first network device as an example, the network device 1 is a non-terrestrial network device, for example, the network device 1 is a satellite or a drone, which is not limited in this application.

As shown in (a) of FIG. 5 , the method may include the following steps.

501 - a , the terminal device receives first indication information from network device 1 .

Correspondingly, the network device 1 sends the first indication information to the terminal device.

For example, when the terminal device is within the coverage of network device 1 and network device 1 provides services to the terminal device, network device 1 sends the first indication information to the terminal device. The first indication information is used to instruct the terminal device to access network device 1 when the terminal device leaves the coverage of network device 1 and then re-enters the coverage of network device 1, or the first indication information is used to instruct the terminal device to access network device 1 and prohibit access to network devices other than network device 1.

502-a, the terminal device changes from the connected state to the first state.

It should be understood that when the terminal device leaves the coverage of the network device 1, the terminal device changes from the connected state to the first state.

As an example, the terminal device leaves the coverage of network device 1 at a first moment, and the first moment may be indicated to the terminal device by network device 1. The first moment may be determined by network device 1 based on its own movement trajectory and the location information of the terminal device. At the first moment, the network device 1 stops providing services to the terminal device.

It should also be understood that the first state includes one or more of the following: a suspended connection state, a suspended idle state, or an inactive state of the access layer AS of the terminal device.

[Corrected 12.03.2025 in accordance with Article 91]
The terminal device's access layer AS suspended connection state is a special connection state in which the terminal device retains its context information. This state can be understood as the terminal device remaining in the connected state and halting all AS layer processing operations. For example, the terminal device stops detecting RLF, stopping measurements, and stopping paging monitoring.

Among them, the idle state with suspended is a special idle state. In the idle state with suspended, the terminal device retains the context information of the terminal device and does not release the context information of the terminal device.

Among them, the terminal device still keeps monitoring the network in the inactive state so that it can be reactivated and communicate with the network when needed.

It should also be understood that step 502 - a is an optional step, and the remaining steps of (a) in FIG. 5 may not depend on the existence of step 502 - a.

503 - a , the terminal device sends a first request message to the network device 1 .

Correspondingly, the network device 1 receives the first request information from the terminal device.

For example, the terminal device receives a first request message from network device 1, and the terminal device leaves the coverage of the network device 1 and changes from the connected state to the first state. When the terminal device re-enters the coverage of the network device 1, the terminal device sends a first request message to the network device 1 for requesting access to the network device 1.

As shown in (b) of FIG5 , the method may include the following steps.

501 - b , the terminal device receives the first information from the network device 1 .

Accordingly, the network device 1 sends the first information to the terminal device.

For example, when the terminal device is within the coverage of the network device 1 and the network device 1 provides services to the terminal device, the network device 1 sends the first information to the terminal device.

Optionally, the first information includes indication information for indicating an available area of the network device 1. Optionally, the range of the available area may be smaller than the cell under the coverage of the network device 1, or in other words, the available area is a part of the cell provided by the network device 1 (for example, the cell center area).

502-b, the terminal device changes from the connected state to the first state.

It should be understood that when the terminal device leaves the coverage of the network device 1, the terminal device changes from the connected state to the first state.

It should also be understood that step 502 - b is an optional step, and the remaining steps of (b) in FIG. 5 may not depend on the existence of step 502 - b.

503 - b , the terminal device sends a first request message to the network device 1 .

Correspondingly, the network device 1 receives the first request information from the terminal device.

For example, when the terminal device is located in the available area of the network device 1 , the terminal device sends first request information to the network device 1 according to the first information, where the first request information is used to request access to the network device 1 .

It should be understood that the terminal device is located in the available area indicated by network device 1, and the terminal device executes step 503-b to send the first request information to network device 1. Of course, assuming that the terminal device is not located in the available area indicated by network device 1, and the terminal device is within the coverage of another network device (for example, network device 2), the terminal device can send the first request information to network device 2, as shown in step 503-b':

503-b’, the terminal device sends a first request message to the network device 2.

Correspondingly, the network device 2 receives the first request information from the terminal device.

The terminal device is located in the coverage area of the network device 2.

It should be understood that, assuming that the terminal device is not located in the available area indicated by network device 1, and the terminal device is located in the coverage area of another network device (e.g., network device 2), the terminal device can send a first request message to network device 2. When the terminal device determines, based on the first information, that the terminal device is not in the available area indicated by network device 1, the terminal device can select another network device that covers the terminal device to request access. Specifically, this application does not limit the specific process of how the terminal device selects a network device from the network devices that cover the terminal device to request access. For example, the terminal device can select any network device that covers the terminal device to request access.

It should be understood that in the method shown in (a) of FIG. 5 and the method shown in (b) of FIG. 5 , network device 1 instructs the terminal device to access network device 1 through the first indication information, or network device 1 instructs the terminal device to access network device 1 through the first information including only the first network device. The network device 1 has the context information of the terminal device, thereby avoiding the change of the service network device of the terminal device due to the movement of network device 1, saving the resource overhead of network device 1 forwarding the context information of the terminal device. At the same time, when the terminal device leaves the coverage of network device 1, the terminal device enters the first state from the connected state. In the first state, the terminal device retains the context information of the terminal device, so that the terminal device can correctly access the network device later, ensuring secure communication between the terminal device and the network.

FIG6 is a flow chart of another communication method provided in an embodiment of the present application.

It should be understood that in the method shown in FIG6, the first network device is network device 1 as an example, and the at least one third network device is network device 2 and network device 3 as examples, wherein network device 2 can be used as the second network device in the at least one third network device, and network device 3 can be used as an example of other network devices other than the second network device in the at least one third network device. The network devices 1, 2, and 3 are all non-terrestrial network devices. For example, the network devices 1, 2, and 3 are respectively satellites or drones, which are not limited in this application. As shown in FIG6, the method may include the following steps.

601. Network device 1 sends T_service information to terminal device.

Correspondingly, the terminal device receives T_service information from the network device 1 .

It should be understood that network device 1 is a source service network device that provides services to terminal devices. Due to the mobility of network device 1, the terminal device is not within the coverage of network device 1 at a certain moment, that is, network device 1 cannot provide services to the terminal device at that moment. The time indicated by the T_service information (for example, the first moment) is the time when the terminal device 1 leaves the coverage of network device 1, or it can be understood that the first moment indicated by the T_service information is the time when the network device 1 no longer provides services to the terminal device, or it can also be understood that the first moment indicated by the T_service information is the deadline for the network device 1 to provide services to the terminal device.

It should also be understood that step 601 is optional. The network device 1 may not separately indicate the t_service information to the terminal device. When the terminal device determines that it is not within the coverage of the network device 1 or that it cannot connect to the network device 1, the terminal device can simply update its own status.

602. Network device 1 sends first information to the terminal device.

Accordingly, the terminal device receives the first information from the network device 1 .

It should be understood that the first information includes one or more network devices (e.g., at least one third network device), and the at least one third network device is a potential target network device that provides services to the terminal device. For example, the at least one third network device includes network device 2 and network device 3.

In one possible implementation, the first information includes one or more of the following: ephemeris information of network device 2, ephemeris information of network device 3, time information when network device 2 is connected to a ground gateway, time information when network device 3 is connected to a ground gateway, location information when network device 2 is connected to a ground gateway, or location information when network device 3 is connected to a ground gateway.

In another possible implementation manner, the first information further includes: indication information for indicating the available area of the network device 2, and/or indication information for indicating the available area of the network device 3.

It should be understood that the present application does not limit the order in which step 602 and step 601 are executed. For example, step 601 may be executed before step 602, or step 602 may be executed after step 601, or step 601 and step 602 may be executed simultaneously. When step 601 and step 602 can be executed simultaneously, the T_service information and the first information sent by the network device 1 may be carried in the same message or in different messages, and this application does not limit this.

603. The terminal device changes from the connected state to the first state.

For example, the terminal device receives T_service information from network device 1. After the moment indicated by the T_service information (for example, the first moment) is reached, the terminal device changes from the connected state to the first state; or, when the terminal device determines that it has left the coverage of network device 1, the terminal device changes from the connected state to the first state.

The first state includes any one of the following: an access layer suspended connection state of the terminal device, a special idle state (such as a suspended idle state), an inactive state, or an idle state.

[Corrected 12.03.2025 in accordance with Article 91]
It should be understood that if the first state is the access layer suspended connection state of the terminal device, when the terminal device leaves the coverage area of network device 1, the terminal device changes from the connected state to the access layer suspended connection state. The terminal device stops access layer operations, for example, the terminal device stops detecting RLF, stops measuring, stops monitoring paging, etc. Optionally, the terminal device can stop all access layer operations. The terminal device retains the terminal device's context information to facilitate subsequent correct access to a new network device.

It should be understood that when the first state is a special idle state or an inactive state, the special idle state may be a suspended idle state (for example, IDLE with suspended). When the terminal device changes from a connected state to a suspended idle state or an inactive state, the terminal device retains the context information of the terminal device to facilitate subsequent correct access to a new network device.

It should be understood that the change in the terminal device state in step 603 when the terminal device leaves the coverage of the network device 1 can be regarded as an internal implementation operation of the terminal device. In the specific implementation process, step 603 may not be reflected in the actual operation.

604. Network device 1 sends second information to the core network device.

Correspondingly, the core network device receives the second information from the network device 1 .

For example, when network device 1 covers a terrestrial gateway, network device 1 sends second information to the core network device through the terrestrial gateway, wherein the second information includes first context information of the terminal device, and the first context information of the terminal device includes identification information of the UE.

Optionally, the second information may further include identification information of network device 2 and identification information of network device 3.

In one possible implementation, when the network device 1 has an unused NH, the first context information of the terminal device includes key #1 and NCC. The key #1 is determined by the network device 1 based on the unused NH. The specific determination method is similar to the determination method of KeNB* in the update of KeNB in the above-mentioned 2) switching scenario (for example, vertical derivation). Please refer to the above detailed description for details.

In another possible implementation, when the network device 1 does not have an unused NH, the first context information of the terminal device includes second indication information, and the second indication information is used to instruct the core network device to determine the NH and the NCC.

In another possible implementation, when the network device 1 does not have an unused NH, the first context information of the terminal device does not include the key #1, the NCC and the second indication information.

605 , the core network device sends the second context information of the terminal device to network device 2 and network device 3 .

Correspondingly, network device 2 and network device 3 receive the second context information of the terminal device from the core network device.

For example, the core network device receives the first context information of the terminal device from network device 1. Based on the first context information of the terminal device, the core network device sends the second context information of the terminal device to network devices 2 and 3. The second context information of the terminal device includes the identification information and NCC of the terminal device, as well as key #1 or NH.

In one possible implementation, when the first context information of the terminal device includes key #1 and NCC, the core network device forwards the first context information of the terminal device to network device 2 and network device 3 via the second context information of the terminal device. The second context information of the terminal device includes key #1 and NCC.

In another possible implementation, when the first context information of the terminal device includes second indication information, the core network device generates NH and NCC according to the second indication information, and sends the second context information of the terminal device carrying NH and NCC to network device 2 and network device 3.

In another possible implementation, when the first context information of the terminal device does not include key #1, NCC and second indication information, the core network device generates NH and NCC, and sends the second context information of the terminal device carrying NH and NCC to network device 2 and network device 3.

It should be understood that the core network device sends the second context information of the terminal device to network device 2 and network device 3, and the second context information of the terminal device is carried in the same message and sent to network device 2 and network device 3 at the same time, or the second context information of the terminal device is carried in different messages and sent to network device 2 and network device 3 successively. This application does not limit this.

It should also be understood that when the core network device sends the second context information of the terminal device to network device 2 and network device 3, the core network device is within the coverage area of network device 2 and network device 3, respectively, and the core network device can wirelessly communicate with network device 2 and network device 3. For example, when network device 2 moves to a covered ground gateway, the core network device sends the second context information of the terminal device to network device 2 via the ground gateway.

606 , network device 2 and network device 3 send indication information for indicating the available area of network device 2 and indication information for indicating the available area of network device 3 to the terminal device.

Correspondingly, the terminal device receives indication information from network device 2 and network device 3 respectively, which is used to indicate the available areas of the respective network devices.

It should be understood that, taking network device 2 as an example, network device 2 may broadcast indication information indicating the available area of network device 2 in a system message. When a terminal device enters the coverage area of network device 2, the terminal device may receive the indication information indicating the available area of network device 2. For example, the system message may be a master information block (MIB) or a system information block (SIB).

It should also be understood that network device 2 and network device 3 sending indication information indicating the available area of network device 2 and the available area of network device 3 to the terminal device is an optional step. If the first information in step 602 includes indication information indicating the available area of network device 2 and the available area of network device 3, step 606 does not need to be performed.

607 , the terminal device sends first request information to the network device 2 .

Correspondingly, the network device 2 receives the first request information from the terminal device, wherein the first request information includes the identification information of the terminal device.

For example, the terminal device selects network device 2 as the target network device for providing services to the terminal device based on a certain rule or a certain preset condition. The certain rule or the certain preset condition may be predetermined by the system, pre-configured by the protocol, or determined by the terminal device itself, which is not limited in this application.

Assume that the terminal device selects network device 2 as the target network device based on the available areas of multiple network devices (eg, network device 2 and network device 3), and sends first request information for requesting access to network device 2 to network device 2.

It is also assumed that the terminal device determines the transmission delays of network device 2 and network device 3 respectively based on the ephemeris information of the network device (e.g., network device 2, network device 3) indicated in the received first information, the location information connected to the gateway station, the time information and other parameters, selects the network device with the smallest delay (e.g., network device 2) as the target network device, and sends a first request information to network device 2 for requesting access to network device 2.

In one possible implementation, the first request information may be a request information for RRC re-establishment (e.g., RRC connection reestablishment request) or a request information for RRC connection resumption. When the first request information is a request information for RRC re-establishment, the first request information may further include a cause value for indicating re-establishment, and the cause value may be "other failure", or the cause value may be a cause value related to the terminal device accessing the network device 2, and the cause value is related to the S&F scenario. When the first request information is a request information for RRC resumption (e.g., RRC connection resume request), the first request information may further include a cause value for indicating resumption, and the cause value may be "delayTolerantAccess-v1020", or the cause value may be a cause value related to the terminal device accessing the network device 2, and the cause value is related to the S&F scenario. In one implementation, when the first state is a connection state suspended by the access layer, the first request message may be a request message for RRC re-establishment; when the first state is a special idle state or inactive state, the first request message may be a request message for RRC recovery establishment.

It should be understood that the identification information of the terminal device includes: the cell radio network temporary identifier C-RNTI of the terminal device in the first cell, wherein the first cell is a cell providing services to the terminal device within the coverage of the network device 1. The first cell may also be referred to as a source service cell providing services to the terminal device. Optionally, the identification information of the terminal device may also include one or more of the following: the physical cell identifier PCI of the first cell, the location information of the terminal device, the identification information of the first network device, or the identification information of the first cell.

608. Network device 2 sends first response information to the terminal device.

Correspondingly, the terminal device receives the first response information from the network device 2 .

For example, after network device 2 receives the first request information from the terminal device, network device 2 authenticates (or authorizes) the terminal device based on the terminal device identification information in the first request information and the terminal device identification information in the second context information of the terminal device received in step 605. When network device 2 successfully authenticates the terminal device and determines that the terminal device is a legitimate device, network device 2 sends a first response information to the terminal device, where the first response information is used to respond to the first request information.

It should be understood that when network device 2 determines that the terminal device is a legal device, the network device 2 accepts the access of the terminal device, and the network device 2 sends the first response information to the terminal device. The first response information includes NCC, which is the NCC in the second context information of the terminal device received by network device 2 from the core network device. The NCC can come from network device 1, or the NCC is determined by the core network device. This application does not limit this.

It should also be understood that when the network device 2 determines that the terminal device is not a legitimate device, there is no need to perform step 608 and subsequent steps.

609 , the terminal device communicates securely with the network device 2 .

It should be understood that after the terminal device receives the first response information from network device 2, the terminal device determines the key (for example, key #1) for secure communication with network device 2 based on the NCC in the first response information. The key #1 determined by network device 2 can be the key #1 determined by network device 1, or the key #1 determined by network device 2 based on the NH determined by the core network and the NCC.

It should also be understood that the specific method by which the terminal device determines key #1 based on the NCC, and the network device 2 determines key #1 based on the NCC, is similar to the method for determining KeNB* in the update of KeNB in the above-mentioned 2) switching scenario (e.g., vertical derivation). For details, please refer to the above detailed introduction and will not be repeated here.

It should also be understood that key #1 is used for secure communication between the terminal device and the network device 2.

610. Network device 2 sends third indication information to the core network device.

Correspondingly, the core network device receives the third indication information from the network device 2 .

For example, if network device 2 determines that the terminal device has successfully accessed network device 2, network device 2 may send third indication information to the core network device, where the third indication information is used to indicate that the terminal device has successfully accessed the second network device. The third indication information includes identification information of the terminal device, such as the NG interface application layer protocol identifier (UE NGAP ID) of the terminal device. The third indication information may also include identification information of network device 3, such as the eNB ID of network device 3, the satellite identifier of network device 3, or the IP address of network device 3. Optionally, if the third indication information includes identification information of network device 3, the identification information of the terminal device may use the identification information of the terminal device under network device 3, such as the C-RNTI. This method eliminates the need for the core network device to modify the identification of the terminal device. The core network device only needs to obtain the identification information of network device 3 and can indicate the terminal device to network device 3 by carrying the identification information of the terminal device that is recognizable by network device 3.

611. The core network device sends release indication information to network device 3.

Correspondingly, the network device 3 receives the release indication information from the core network device.

For example, after the core network device receives the third indication information from network device 2, the core network device determines, based on the third indication information, that the terminal device has successfully accessed network device 2. The core network device then determines to send release indication information to network device 3, where the release indication information is used to instruct the release of the second context information of the terminal device. The release indication information includes identification information of the terminal device, such as the UE NGAP ID of the terminal device or the C-RNTI of the terminal device under network device 3.

It should also be understood that after the core network device receives the third indication information from network device 2, the core network device can determine at least one third network device based on the identification information of the at least one third network device included in the second information in step 604, and send the release indication information to other network devices (e.g., network device 3) among the at least one third network device except network device 2. Correspondingly, after network device 3 receives the release indication information from the core network device, it releases the context information of the terminal device based on the identification information of the terminal device in the release indication information.

According to the method shown in Figure 6 above, when the terminal device leaves the coverage of the network device 1, that is, when the source network device that provides services to the terminal device (such as network device 1) no longer provides services to the terminal device, the terminal device changes from the connected state to the first state. The terminal device can retain the context information of the terminal device in the first state, so as to facilitate correct access to the new target network device that provides services to the terminal device (such as network device 2). At the same time, when the network device 1 covers the gateway, it forwards the first context information of the terminal device to the potential target network device in the first information through the core network device, so that when the subsequent terminal device initiates a request to the target network device, it can access accurately and quickly, thereby ensuring normal communication between the terminal device and the network. In addition, when the terminal device accesses a new network device (such as network device 2), the network device 2 sends a third indication message to the core network device to indicate that the terminal device has successfully accessed network device 2, and the core network device sends a release indication message to other network devices in the first information to indicate the release of the terminal device context information, thereby saving resource overhead of other network devices.

Based on the method shown in Figure 6 above, when the terminal device leaves the coverage of network device 1, the terminal device changes from a connected state to a first state. Wherein, the first state may also include an idle state. When the first state is an idle state, when the terminal device leaves the coverage of network device 1, the terminal device may also release the context information of the terminal device and enter an idle state. When the subsequent terminal device enters the coverage of a network device (such as network device 2), the terminal device selects network device 2 to initiate an initial access process. Accordingly, the terminal device and network device 2 use a key derived from the root key Kasme for encrypted communication according to the key acquisition method in the initial access scenario. Wherein, the key acquisition between the terminal device and network device 2 in the initial access scenario is similar to the acquisition of KeNB by the terminal device and the base station in the above 1) initial access scenario. The terminal device derives KeNB based on the root key Kasme, and the base station receives KeNB derived from the root key Kasme from the MME. The terminal device and the base station use KeNB for encrypted communication. Please refer to the above detailed introduction for details, which will not be repeated here.

FIG7 is a flow chart of another communication method provided in an embodiment of the present application.

It should be understood that in the method shown in FIG7 , the first network device is network device 1, and the at least one third network device is network device 2 and network device 3, respectively. Network device 2 can be used as the second network device in the at least one third network device, and network device 3 can be used as an example of the other network devices in the at least one third network device except the second network device. Network device 1, network device 2, and network device 3 are all non-terrestrial network devices. For example, network device 1, network device 2, and network device 3 are respectively satellites or drones, which are not limited in this application. As shown in FIG7 , the method may include the following steps.

701. Network device 1 sends T_service information to terminal device.

Correspondingly, the terminal device receives T_service information from the network device 1 .

702. Network device 1 sends first information to the terminal device.

Accordingly, the terminal device receives the first information from the network device 1 .

703. The terminal device changes from the connected state to the first state.

For example, the terminal device receives T_service information from the network device 1. After the time indicated by the T_service information (eg, the first time) is reached, the terminal device changes from the connected state to the first state.

It should be understood that the above steps 701 to 703 are similar to steps 601 to 603 in FIG. 6 . For details, please refer to the detailed description of steps 601 to 603 .

704 , the terminal device sends first request information to the network device 2 .

Correspondingly, the network device 2 receives the first request information from the terminal device.

For example, when the network device 2 covers the terminal device, the terminal device sends first request information to the network device 2 , where the first request information is used to request access to the network device 2 .

In a possible implementation, the terminal device may select network device 2 from multiple network devices according to a certain rule or a certain preset condition, and send the first request information to network device 2.

It should be understood that the certain rule or condition may be predetermined by the system, pre-configured by the protocol, or determined by the terminal device itself, and this application does not limit this.

For example, the terminal device selects a network device based on the available areas of multiple network devices and sends a first request message to the network device. The indication information for indicating the available area of the network device can be carried in the first message, or carried in the system information broadcast by the network device, etc.

For another example, the terminal device selects a network device with the smallest delay based on the delays of multiple network devices and sends the first request information to the network device. The delays of the multiple network devices can be determined by the terminal device based on information such as ephemeris information, time information, and location information included in the first information.

For another example, the terminal device selects a network device having the context information of the terminal device based on whether each of the multiple network devices has the context information of the terminal device, and sends the first request information to the network device. The terminal device can determine to select the network device having the context information of the terminal device based on information in the first information indicating whether each of the multiple network devices has the context information of the terminal device.

It should be understood that the terminal device can select network device 2 based on any of the above examples and send a first request message to network device 2, or select network device 2 based on any two or three of the above examples and send a first request message to network device 2. This application does not limit this.

It should also be understood that after network device 2 receives the first request information from the terminal device, assuming that network device 2 has the context information of the terminal device, network device 2 further determines whether to accept the access request of the terminal device based on the first request information, as shown in the following scenario 1. Furthermore, assuming that network device 2 does not have the context information of the terminal device, after receiving the first request information, network device 2 may request the core network device to obtain the context information of the terminal device, as shown in the following scenario 2.

Case 1

705. Network device 2 sends first response information to the terminal device.

Correspondingly, the terminal device receives the first response information from the network device 2 .

For example, after receiving the first request information from the terminal device, the network device 2 authenticates the terminal device based on the first request information and the locally stored context information of the terminal device. If the network device 2 successfully authenticates the terminal device, the network device 2 sends a first response information to the terminal device. The first response information is used to respond to the first request information and includes the NCC.

It should be understood that the context information of the terminal device stored in the network device 2 may be sent from the network device 1 via the core network device. For example, in step 605 of the method shown in FIG6 , the network device 2 receives the second context information of the terminal device sent from the core network device and stores the second context information of the terminal device locally in the network device 2. The network device 2 may also obtain the context information of the terminal device through other means, which will not be described in detail in this application.

706. Network device 2 communicates securely with the terminal device.

It should be understood that after the terminal device receives the first response information from network device 2, the terminal device determines the key (for example, key #1) for secure communication with network device 2 based on the NCC in the first response information. The key #1 of network device 2 may be from the source network device (for example, network device 1) that provides services to the terminal device, or it may be determined by network device 2 itself based on NH and NCC. This application does not limit this.

It should also be understood that the specific method by which the terminal device determines key #1 based on NCC and the network device 2 determines key #1 is similar to the method by which the terminal device determines KeNB* described above. Please refer to the above description for details and will not be repeated here.

It should also be understood that key #1 is used for secure communication between the terminal device and the network device 2.

707. Network device 2 sends third indication information to the core network device.

Correspondingly, the core network device receives the third indication information from the network device 2 .

For example, when network device 2 determines that the terminal device has successfully accessed network device 2, network device 2 sends third indication information to the core network device, where the third indication information is used to indicate that the terminal device has successfully accessed the second network device. The third indication information includes identification information of the terminal device.

708. The core network device sends release indication information to network device 3.

Correspondingly, the network device 3 receives the release indication information from the core network device.

For example, after the core network device receives the third indication information from network device 2, the core network device determines, based on the third indication information, that the terminal device has successfully accessed network device 2. The core network device then determines to send release indication information to network device 3, where the release indication information is used to instruct the release of the second context information of the terminal device. The release indication information includes identification information of the terminal device.

It should be understood that the core network device can send the release indication information to the network device (e.g., network device 3) having the context information of the terminal device according to the third indication information. Steps 707 and 708 are both optional steps. When other network devices do not receive the context information of the terminal device and/or do not store the context information of the terminal device locally on the network device side, steps 707 and 708 do not need to be performed.

Case 2

705’, network device 2 sends a second request message to the core network device.

Correspondingly, the core network device receives the second request information from the network device 2 .

For example, after network device 2 receives the first request information from the terminal device, the network device 2 does not have the context information of the terminal device. The network device 2 sends a second request information to the core network device based on the first request information. The second request information is used to request the context information of the terminal device. The second request information includes the identification information of the terminal device.

It should be understood that when the network device 2 covers the ground gateway, the network device 2 sends the second request information to the core network device through the ground gateway.

706’, the core network device sends a third request message to network device 1.

Correspondingly, the network device 1 receives the third request information from the core network device.

For example, after the core network device receives the second request information from network device 2, when network device 1 covers a ground gateway station, the core network device sends a third request information to network device 1 through the ground gateway station. The third request information is used to request the context information of the terminal device, and the third request information includes the identification information of the terminal device.

707’, network device 1 sends the first context information of the terminal device to the core network device.

Correspondingly, the core network device receives the first context information of the terminal device from the network device 1 .

It should be understood that after network device 1 receives the third request information from the core network device, network device 1 authenticates the terminal device based on the terminal device's identification information in the third request information. If the terminal device is successfully authenticated and network device 1 is covered by a ground gateway, network device 1 sends the first context information of the terminal device to the core network device via the ground gateway.

In one possible implementation, when the network device 1 has an unused NH, the first context information of the terminal device includes key #1 and NCC. The key #1 is determined by the network device 1 based on the unused NH. The specific determination method is similar to the determination method of KeNB* in the update of KeNB in the above-mentioned 2) switching scenario (for example, vertical derivation). Please refer to the above detailed description for details.

In another possible implementation, when the network device 1 does not have an unused NH, the first context information of the terminal device includes second indication information, and the second indication information is used to instruct the core network device to determine the NH and the NCC.

In another possible implementation, when the network device 1 does not have an unused NH, the first context information of the terminal device does not include the key #1, the NCC and the second indication information.

It should also be understood that when network device 1 authenticates the terminal device based on the terminal device identification information in the third request information and determines that the terminal device is not a legitimate device, there is no need to execute step 707' and subsequent steps.

708’, the core network device sends the second context information of the terminal device to network device 2.

Correspondingly, the network device 2 receives the second context information of the terminal device from the core network device.

For example, the core network device receives the first context information of the terminal device from the network device 1 , and sends the second context information of the terminal device to the network device 2 based on the first context information of the terminal device.

In one possible implementation, when the first context information of the terminal device includes key #1 and NCC, the core network device forwards the first context information of the terminal device to network device 2 through the second context information of the terminal device, and the second context information of the terminal device includes key #1 and NCC.

In another possible implementation method, when the first context information of the terminal device includes second indication information, the core network device determines the NH and NCC based on the second indication information, and sends the second context information of the terminal device carrying NH and NCC to the network device 2 based on the first context information of the terminal device.

In another possible implementation, when the first context information of the terminal device does not include key #1, NCC and second indication information, the core network device generates NH and NCC, and sends the second context information of the terminal device carrying NH and NCC to the network device 2 based on the first context information of the terminal device.

It should be understood that when the core network device sends the second context information of the terminal device to network device 2, the core network device is within the coverage of network device 2 and can wirelessly communicate with network device 2. For example, when network device 2 moves to a covered ground gateway, the core network device sends the second context information of the terminal device to network device 2 through the ground gateway.

709’, network device 2 sends indication information for indicating its own available area.

Correspondingly, the terminal device receives indication information indicating its own available area from the network device 2 .

It should be understood that when the terminal device is within the coverage of network device 2, the terminal device can receive a system message broadcast from network device 2, which may include indication information for indicating its own available area, or the network device 2 sends the indication information for indicating its own available area through a separate message.

It should also be understood that step 709' is an optional step. When the first information in step 702 includes indication information for indicating the available area of network device 2, step 709' does not need to be executed.

710’, the terminal device sends a first request message to the network device 2.

Correspondingly, the network device 2 receives the first request information from the terminal device.

For example, when the terminal device enters the coverage area of the network device 2 , the terminal device sends first request information to the network device 2 , where the first request information is used to request access to the network device 2 .

It should be understood that step 710' is similar to step 607 in FIG. 6 and step 704 in FIG. 7 . For details, please refer to the detailed description of step 607 in FIG. 6 and step 704 in FIG. 7 .

711’, network device 2 sends a first response message to the terminal device.

Correspondingly, the terminal device receives the first response information from the network device 2 .

For example, after network device 2 receives the first request information from the terminal device, network device 2 sends a first response information to the terminal device according to the first request information, where the first response information is used to respond to the first request information and includes the NCC in the second context information of the terminal device.

It should be understood that when network device 2 accepts access from the terminal device, the network device 2 sends the first response information to the terminal device. The first response information includes NCC. The NCC is the NCC in the second context information of the terminal device received by network device 2 from the core network device. The NCC can come from network device 1, or the NCC is determined by the core network device. This application does not limit this.

712’, the terminal device communicates securely with the network device 2.

It should be understood that after the terminal device receives the first response information from network device 2, the terminal device determines the key (for example, key #1) for secure communication with network device 2 based on the NCC in the first response information. The key #1 determined by network device 2 can be the key #1 determined by network device 1, or the key #1 determined by network device 2 based on the NH determined by the core network and the NCC.

It should also be understood that the specific method by which the terminal device determines key #1 based on the NCC, and the network device 2 determines key #1 based on the NCC, is similar to the method for determining KeNB* in the update of KeNB in the above-mentioned 2) switching scenario (e.g., vertical derivation). For details, please refer to the above detailed introduction and will not be repeated here.

It should also be understood that key #1 is used for secure communication between the terminal device and the network device 2.

According to the method shown in FIG7 , due to the mobility of network device 1, when a terminal device leaves the coverage area of network device 1, the terminal device changes from a connected state to a first state and sends a first request message to network device 2 requesting access. Considering that network device 2 has the context information of the terminal device, after receiving the first request message, network device 2 authenticates the terminal device based on the terminal device identification information in the first request message. If the authentication is successful, network device 2 sends a first response message to the terminal device. The terminal device and network device 2 communicate securely based on key #1, thereby ensuring secure communication between the terminal device and the network. Furthermore, considering that network device 2 does not have the context information of the terminal device, network device 2 requests the core network device to obtain the context of the terminal device. The core network device requests the context information of the terminal device from network device 1, and network device 1 authenticates the terminal device. If the authentication is successful, network device 1 sends the first context information of the terminal device to the core network device, and the core network device further sends the second context information of the terminal device to network device 2. The network device 2 and the terminal device communicate securely based on the key #1, thereby ensuring secure communication between the terminal device and the network.

FIG8 is a flow chart of another communication method provided in an embodiment of the present application.

It should be understood that in the method shown in FIG8 , the first network device is network device 1, and the at least one third network device is network device 2 and network device 3, respectively. Network device 2 can be used as the second network device in the at least one third network device, and network device 3 can be used as an example of the other network devices in the at least one third network device except the second network device. Network device 1, network device 2, and network device 3 are all non-terrestrial network devices. For example, network device 1, network device 2, and network device 3 are respectively satellites or drones, which are not limited in this application. As shown in FIG8 , the method may include the following steps.

801. Network device 1 sends T_service information to terminal device.

Correspondingly, the terminal device receives T_service information from the network device 1 .

802. Network device 1 sends first information to the terminal device.

Accordingly, the terminal device receives the first information from the network device 1 .

803. The terminal device changes from the connected state to the first state.

For example, the terminal device receives T_service information from the network device 1. After the time indicated by the T_service information (eg, the first time) is reached, the terminal device changes from the connected state to the first state.

It should be understood that the above steps 801 to 803 are similar to steps 601 to 603 in FIG. 6 . For details, please refer to the detailed description of steps 601 to 603 .

804. Network device 1 sends first context information of the terminal device to the core network device.

Correspondingly, the core network device receives the first context information of the terminal device from the network device 1 .

For example, when the network device 1 covers the ground gateway, the network device 1 sends the first context information of the terminal device to the core network device through the ground gateway. The first context information of the terminal device includes the identification information of the UE.

In one possible implementation, when the network device 1 has an unused NH, the first context information of the terminal device includes key #1 and NCC. The key #1 is determined by the network device 1 based on the unused NH. The specific determination method is similar to the determination method of KeNB* in the update of KeNB in the above-mentioned 2) switching scenario (for example, vertical derivation). Please refer to the above detailed description for details.

In another possible implementation, when the network device 1 does not have an unused NH, the first context information of the terminal device includes second indication information, and the second indication information is used to instruct the core network device to configure NH and NCC for the terminal device.

In another possible implementation, when the network device 1 does not have an unused NH, the first context information of the terminal device does not include the key #1, the NCC and the second indication information.

805 , network device 2 and network device 3 send indication information for indicating the available area of network device 2 and indication information for indicating the available area of network device 3 to the terminal device.

It should be understood that step 805 is similar to step 606 in FIG. 6 , and both are optional steps. For details, please refer to the introduction in FIG. 6 .

806 , the terminal device sends first request information to the network device 2 .

Correspondingly, the network device 2 receives the first request information from the terminal device.

It should be understood that step 806 is similar to step 607 in FIG. 6 , and for details, please refer to the introduction in FIG. 6 .

807. Network device 2 sends second request information to the core network device.

Correspondingly, the core network device receives the second request information from the network device 2 .

For example, after network device 2 receives the first request information from the terminal device, the network device 2 does not have the context information of the terminal device. The network device 2 sends a second request information to the core network device based on the first request information. The second request information is used to request the context information of the terminal device. The second request information includes the identification information of the terminal device.

It should be understood that when the network device 2 covers the gateway, the network device 2 sends the second request information to the core network device through the gateway.

808 , the core network device sends the second context information of the terminal device to network device 2 .

Correspondingly, the network device 2 receives the second context information of the terminal device from the core network device.

For example, after receiving the second request information from network device 2, the core network device authenticates the terminal device based on the terminal device's identification information in the second request information. If the authentication is successful, when network device 2 reaches a ground gateway, the core network device sends the second context information of the terminal device to network device 2 via the ground gateway.

It should be understood that the core network device determines the second context information of the terminal device based on the first context information of the terminal device received in step 804. For a detailed introduction on how the core network device determines the second context information of the terminal device based on the first context information of the terminal device, please refer to the detailed introduction in step 708' in Figure 7 above, which will not be repeated here.

809 , the terminal device sends first request information to the network device 2 .

Correspondingly, the network device 2 receives the first request information from the terminal device.

For example, when the terminal device enters the coverage of network device 2, the terminal device receives the system message broadcast by network device 2. After the terminal device receives the system message of network device 2, the terminal device can send a first request message to network device 2, and the first request message is used to request access to network device 2.

It should be understood that step 809 is similar to step 607 in FIG. 6 and step 806 in FIG. 8 . For details, please refer to the detailed description of step 607 in FIG. 6 and step 806 in FIG. 8 .

810. Network device 2 sends first response information to the terminal device.

Correspondingly, the terminal device receives the first response information from the network device 2 .

For example, after network device 2 receives the first request information from the terminal device, network device 2 sends a first response information to the terminal device according to the first request information, and the first response information is used to respond to the first request information. The first response information includes the NCC in the second context information of the terminal device.

It should be understood that when network device 2 accepts access from the terminal device, the network device 2 sends the first response information to the terminal device. The first response information includes NCC. The NCC is the NCC in the second context information of the terminal device received by network device 2 from the core network device. The NCC can come from network device 1, or the NCC is determined by the core network device. This application does not limit this.

811. The terminal device communicates securely with the network device 2.

It should be understood that after the terminal device receives the first response information from network device 2, the terminal device determines the key (for example, key #1) for secure communication with network device 2 based on the NCC in the first response information. The key #1 determined by network device 2 can be the key #1 determined by network device 1, or the key #1 determined by network device 2 based on the NH determined by the core network and the NCC. This application does not limit this.

It should also be understood that the terminal device determines key #1 based on the NCC, and the network device 2 determines the specific method of determining key #1 based on the NCC is similar to the method of determining KeNB* in the update of KeNB in the above-mentioned 2) switching scenario (for example, vertical derivation). For details, please refer to the above detailed introduction and will not be repeated here.

It should also be understood that key #1 is used for secure communication between the terminal device and the network device 2.

According to the method shown in FIG8 , due to the mobility of network device 1, when the terminal device leaves the coverage of network device 1, the terminal device changes from the connected state to the first state and sends a first request message for access request to network device 2. When network device 1 covers a ground gateway, the network device 1 can send the first context information of the terminal device to the core network device. When the core network device receives a request for the context information of the terminal device from another network device (such as network device 2), the core network device authenticates the terminal device. When the authentication is successful, the core network device determines to send the second context information of the terminal device determined based on the first context information of the terminal device to network device 2, so that network device 2 and the terminal device can communicate based on key #1, ensuring secure communication between the terminal device and the network.

In conjunction with the S&F scenario shown in Figure 4 above, to ensure that the network devices in the S&F scenario only provide services to specific types of terminal devices, only S&F terminal devices can request access to the network devices in the S&F scenario, and other terminal devices (such as legacy UEs or terminal devices with versions prior to R19) are not allowed/prohibited from accessing the network devices in the S&F scenario. In conjunction with the methods shown in Figures 6 to 8 above, Network Device 2 and Network Device 3 are the network devices in the S&F scenario shown in Figure 4, and the terminal devices are S&F terminal devices.

For example, in step 606 of Figure 6, step 709' of Figure 7, and step 805 of Figure 8, the cellBarred information element in the system message (e.g., MIB message/SIB message) broadcast by network device 2 and network device 3 is set to barred. The cellBarred information element is used to indicate that all normal UEs (non-NTN UEs) are denied access.

It should be understood that two special types of terminal devices are introduced in NR: IAB-MT and NCR-MT. These two types of terminal devices may ignore the cellBarred information element in the system message broadcast by the network device. The method provided in the present application introduces the iab-support information element and the ncr-support information element for IAB-MT and NCR-MT in the protocol included in the system message. Among them, the iab-support information element and the ncr-support information element can be located in the SIB message to indicate whether the cell allows IAB-MT or NCR-MT to access. For example, network device 2 and network device 3 set the values corresponding to the iab-support information element and the ncr-support information element in the SIB message to not support.

It should be understood that for R17/R18 versions of NTN, the cellBarredNTN information element was introduced in system messages. This cellBarredNTN information element is used to restrict access by NTN UEs. If the value of cellBarredNTN is notBarred, it indicates that the cell supports NTN UE access; if the value of cellBarredNTN is Barred, it indicates that the cell does not support NTN UE access. Optionally, for R19 S&F satellites, for example, in step 606 in Figure 6, step 709' in Figure 7, and step 805 in Figure 8, the cellBarredNTN information element in the system messages (e.g., MIB messages/SIB messages) broadcast by network devices 2 and 3 is set to barred to indicate that the cell does not support access by standard NTN terminals.

The method provided in this application introduces an indication that the cell supports access by S&F terminal devices. For example, a new information element (e.g., the sfBarred information element) is introduced in the system message. This application does not limit the name of the information element. The value of the sfBarred information element can be "barred (prohibited)/not barred (not prohibited)". If the value of the sfBarred information element is barred (prohibited), it means that the cell does not support access by S&F terminal devices. If the value of the sfBarred information element is not barred (not prohibited), it means that the cell supports access by S&F terminal devices. Generally, for cells within the coverage area of S&F network equipment, the value of sfBarred in the system message is set to "not barred".

Optionally, the value of the sfBarred element in the system message can vary. If a satellite is determined to operate in S&F mode at certain times, the value of the sfBarred element can be set to "not barred", indicating that the satellite provides S&F services or supports access by S&F terminal devices. The satellite can be determined not to operate in S&F mode (operating in normal communication mode) at other times. For example, if the satellite can simultaneously connect to the core network and cover certain terminal devices at certain times, the satellite will set the value of the sfBarred element to "barred", indicating that the satellite does not provide S&F services or does not support access by S&F terminal devices, or that the satellite provides ordinary access services. Optionally, the cellBarredNTN element in the system message may also change. When the satellite operates in S&F mode, the values of the cellBarredNTN element and the cellBarred element may be set to "barred". When the satellite does not operate in S&F mode, the value of the cellBarredNTN element may be set to "not barred" and the value of the cellBarred element may be set to "barred".

Accordingly, for terminal devices with versions prior to R19, they receive system messages and determine that the cell is not allowed to be accessed based on the cellBarred=barred field in the system message. Accordingly, the terminal device will not access the network device corresponding to the cell, that is, it will not initiate an access request to the S&F network device. For IAB-MT and NCR-MT, they receive system messages and determine that the cell is not allowed to be accessed based on the iab-support and ncr-support fields in the system message. Accordingly, IAB-MT and NCR-MT will not access the network device corresponding to the cell.

For terminal devices of R19 and subsequent versions, if the terminal device is a terminal device that supports the S&F function, when determining whether the cell allows itself to access, it determines whether to send a first request message to the corresponding network device based on the value of the sfBarred signaling in the system message. Among them, if sfBarred=not barred in the system message received by the terminal device, it means that the cell supports S&F terminal device access, or the S&F function is turned on, which means that the cell allows access. Accordingly, the terminal device can access the cell, that is, the terminal device can send a first request message to the corresponding network device. Whether the S&F terminal device must read the cellBarred and/or cellBarredNTN information elements in the system message is not limited in this application.

The S&F terminal device determines whether it can request access to the network device based on the system message. There are two possible implementations:

1) The S&F terminal device can first read the cellBarred or cellBarredNTN information element according to the system message. If cellBarred = not barred or cellBarredNTN = not barred, the terminal device directly sends a first request message to the corresponding network device. If cellBarred = barred or cellBarredNTN = barred, the terminal device then reads the sfBarred information element in the system message to determine whether access to the cell is allowed.

2) The S&F terminal device can ignore the values of the cellBarred and cellBarredNTN information elements and directly read the value of the sfBarred information element in the system message to determine whether access to the cell is allowed.

For terminal devices running R19 or later versions, if the terminal device is an NTN terminal device that does not support the S&F function, the cellBarred and sfBarred information elements are ignored. The terminal device determines whether the cell allows the terminal device to access based solely on the value of the cellBarredNTN information element. If the value of the cellBarredNTN information element is not barred, the cell allows the terminal device to access. If the value of the cellBarredNTN information element is barred, the cell does not allow the terminal device to access.

For terminal devices in R19 and later versions, if the terminal device is a non-NTN terminal device (such as a terrestrial network terminal device, a terminal device that does not support NTN functions, or a terminal device that does not support receiving NTN network services), the cellBarredNTN information element and the sfBarred information element are ignored. The terminal device determines whether the cell allows the terminal device to access based only on the value of the cellBarred information element. When the value of the cellBarred information element is not barred, it is determined that the cell allows the terminal device to access. When the value of the cellBarred information element is barred, it is determined that the cell does not allow the terminal device to access.

It should be understood that the system messages broadcast by network devices in the S&F scenario combine the existing cellBarred and cellBarredNTN mechanisms to indicate that access by non-NTN UEs and non-S&F NTN UEs is denied. At the same time, a new sfBarred information element is added to the system messages broadcast by network devices. Only S&F terminal devices are allowed to access the network devices in the S&F scenario, ensuring that the S&F network devices only provide services for specific types of terminal devices.

The methods shown in Figures 6 to 8 above are combined with the ORAN architecture shown in Figure 1. The methods shown in the embodiments of the present application can also be expressed in the following ways.

It should be understood that in the ORAN architecture, the RAN intelligent controller (RIC) is responsible for network device management, operations, and maintenance. This RIC is similar to the operations, administration, and maintenance (OAM) function in the existing ORAN architecture. Therefore, some OAM configurations or information pre-configured for network devices can be sent by the RIC to the network devices via the E2 interface.

For example, in conjunction with the method shown in FIG6 , before step 601, that is, before network device 1 sends T_service information to the terminal device, network device 1 receives the T_service information sent by the RIC of network device 1 via the E2 interface. Before step 602, that is, before network device 1 sends the first information to the terminal device, network device 1 receives the first information sent by the RIC of network device 1 via the E2 interface. Before step 606, that is, before network devices 2 and 3 send indication information indicating an available area, network device 2 receives indication information indicating the available area of network device 2 sent by the RIC of network device 2 via the E2 interface, and network device 3 receives indication information indicating the available area of network device 3 sent by the RIC of network device 3 via the E2 interface.

For another example, in conjunction with the method shown in FIG. 7 , before step 701, that is, before network device 1 sends T_service information to the terminal device, network device 1 receives the T_service information sent by the RIC of network device 1 via the E2 interface. Before step 702, that is, before network device 1 sends the first information to the terminal device, network device 1 receives the first information sent by the RIC of network device 1 via the E2 interface. Before step 709', that is, before network device 2 sends the indication information indicating the available area of network device 2, network device 2 receives the indication information indicating the available area of network device 2 sent by the RIC of network device 2 via the E2 interface.

For another example, in conjunction with the method shown in FIG8 , before step 801, that is, before network device 1 sends T_service information to the terminal device, network device 1 receives the T_service information sent by the RIC of network device 1 via the E2 interface. Before step 802, that is, before network device 1 sends the first information to the terminal device, network device 1 receives the first information sent by the RIC of network device 1 via the E2 interface. Before step 805, that is, before network devices 2 and 3 send indication information indicating the available area, network device 2 receives indication information indicating the available area of network device 2 sent by the RIC of network device 2 via the E2 interface, and network device 3 receives indication information indicating the available area of network device 3 sent by the RIC of network device 3 via the E2 interface.

It should be understood that the above-mentioned methods shown in Figures 6 to 8 are combined with the ORAN architecture, considering the method in which the network device can obtain relevant information through the E2 interface under the ORAN architecture. For example, the RIC of network device 1 can inform network device 1 of the T_service information and the first information that it has stopped providing services to the terminal device. The RIC of network device 2 and the RIC of network device 3 can inform network device 2 and network device 3 of their corresponding available areas, thereby enabling the network device to correctly send relevant information to the terminal device, ensuring the accuracy of the transmitted information.

The communication method provided by the embodiments of the present application is described above in conjunction with Figures 1 to 8. In the various embodiments of the present application, unless otherwise specified or logically conflicting, the terms and/or descriptions between the various embodiments are consistent and can be referenced from each other. The technical features of different embodiments can be combined to form new embodiments based on their inherent logical relationships. For example, any two or all of Figures 5, 6, 7, and 8 can be combined.

The communication device provided in the embodiment of the present application is described in detail below with reference to Figures 9 to 11. It should be understood that the description of the device embodiment corresponds to the description of the method embodiment. Therefore, for matters not described in detail, reference can be made to the method embodiment above. For the sake of brevity, they will not be repeated here.

Figure 9 is a schematic block diagram of a communication device 2000 provided in an embodiment of the present application. The device 2000 includes a transceiver unit 2010 (or transceiver module) and a processing unit 2020 (or processing module). The transceiver unit 2010 can be used to implement corresponding transceiver functions, and the processing unit 2020 can be used to implement corresponding processing functions. The communication device can be used to execute the method performed by the terminal device or network device in any of the embodiments shown in Figures 5 to 8.

Optionally, the transceiver unit 2020 may include a sending unit and a receiving unit. The sending unit is configured to perform the sending operation in the above method embodiment. The receiving unit is configured to perform the receiving operation in the above method embodiment.

Optionally, the communication device 2000 also includes a storage unit, which can be used to store instructions and/or data, and the processing unit 2020 can read the instructions and/or data in the storage unit so that the device implements the relevant actions performed by the terminal device or network device in the aforementioned various method embodiments.

In some implementations, the communication device 2000 is used to perform the actions performed by the terminal device in any of the embodiments shown in Figures 5 to 8 above.

For example, when the terminal device leaves the coverage of the first network device that provides services for the terminal device, the processing unit 2020 is used to change the state of the communication device from a connected state to a first state, and the first state includes any one of the following: a suspended connected state, a suspended idle state, or an inactive state of the access layer AS of the terminal device; the transceiver unit 2010 is used to send a first request message to the second network device, and the first request message is used to request access to the second network device, and the first request message includes the identification information of the terminal device, wherein the first network device and the second network device are non-terrestrial network devices.

The transceiver unit 2010 is also used to perform the reception and transmission processing of the terminal device in the embodiments shown in Figures 5 to 8 above; the processing unit 2020 is also used to perform other processing of the terminal device in addition to reception and transmission in the embodiments shown in Figures 5 to 8 above.

In some implementations, the communication device 2000 is used to perform the actions performed by the network device 1 in any of the embodiments shown in Figures 5 to 8 above.

For example, the transceiver unit 2010 is used to send a first indication message to the terminal device, where the first indication message is used to indicate that the terminal device accesses the first network device when the terminal device leaves the coverage of the first network device and re-enters the coverage of the first network device; the transceiver unit is also used to receive the first request message from the terminal device, where the first request message is used to request access to the first network device, wherein the first network device is a non-ground network device.

It should be understood that the transceiver unit 2010 is also used to perform the receiving and sending processing of the first network device in Figure 5 above.

For example, the transceiver unit 2010 is used to send first information to the terminal device, the first information includes at least one third network device; the transceiver unit 2010 is also used to send second information to the core network device, the second information includes first context information of the terminal device, the first context information of the terminal device includes identification information of the terminal device, wherein the first network device and the at least one third network device are non-terrestrial network devices, and when the first network device has an unused next hop NH, the first context information of the terminal device also includes: a key and a next hop chain calculation NCC, and the key is determined by the first network device according to the NH, or, when the first network device does not have an unused NH, the first context information of the terminal device also includes: second indication information, and the second indication information is used to instruct the core network device to determine the NH and NCC.

The transceiver unit 2010 is further configured to execute the receiving and sending processing of the first network device in the embodiments shown in FIG. 6 to FIG. 8 .

Optionally, the communication device 2000 may further include a processing unit 2020, which is configured to execute other processing except receiving and sending by the first network device in the embodiments shown in FIG. 6 to FIG. 8 .

In some implementations, the communication device 2000 is used to perform the actions performed by the core network device in any of the embodiments shown in Figures 5 to 8 above.

For example, the transceiver unit 2010 is used to receive second information from the first network device, the second information includes first context information of the terminal device, and the first context information of the terminal device includes identification information of the terminal device; the transceiver unit 2010 is also used to send the second context information of the terminal device to at least one third network device, the second context information of the terminal device includes a key and an NCC, or the second context information of the terminal device includes an NCC and a next hop NH, wherein the key is determined based on the NH, and the first network device and the at least one third network device are non-terrestrial network devices.

The transceiver unit 2010 is also used to perform the receiving and sending processing of the core network device in the embodiments shown in Figures 6 to 8 above.

Optionally, the communication device 2000 may further include a processing unit 2020, which is used to perform other processing of the core network device in the embodiments shown in Figures 6 to 8 except for receiving and sending.

In some implementations, the communication device 2000 is used to perform the actions performed by the network device 2 in any of the embodiments shown in Figures 5 to 8 above.

For example, the transceiver unit 2010 is used to receive second context information of a terminal device from a core network device; the transceiver unit 2010 is used to receive first request information from the terminal device, the first request information is used to request access to the second network device, the first request information includes identification information of the terminal device, wherein the second network device is a non-ground network device.

The transceiver unit 2010 is further configured to execute the receiving and sending processing of the second network device in the embodiments shown in FIG. 6 to FIG. 8 .

Optionally, the communication device 2000 may further include a processing unit 2020, which is configured to execute other processing except receiving and sending by the second network device in the embodiments shown in FIG. 6 to FIG. 8 .

It should be understood that the specific process of each unit executing the above corresponding steps has been described in detail in the above method embodiment, and for the sake of brevity, it will not be repeated here.

It should also be understood that the device 2000 herein is embodied in the form of a functional unit. The term "unit" herein may refer to an application specific integrated circuit (ASIC), an electronic circuit, a processor (e.g., a shared processor, a dedicated processor, or a group processor, etc.) and memory for executing one or more software or firmware programs, a combined logic circuit, and/or other suitable components that support the described functions. In an optional example, those skilled in the art will understand that the device 2000 may be specifically the communication device in the above-mentioned embodiment, and may be used to execute the various processes and/or steps corresponding to the communication device in the above-mentioned method embodiments. To avoid repetition, they will not be described here.

The apparatus 2000 of each of the above-mentioned solutions has the function of implementing the corresponding steps performed by the communication device (such as a terminal device or a network device) in the above-mentioned method. The functions can be implemented by hardware, or the corresponding software can be implemented by hardware. The hardware or software includes one or more modules corresponding to the above-mentioned functions; for example, the transceiver unit can be replaced by a transceiver (for example, the sending unit in the transceiver unit can be replaced by a transmitter, and the receiving unit in the transceiver unit can be replaced by a receiver), and other units, such as the processing unit, can be replaced by a processor to respectively perform the sending and receiving operations and related processing operations in each method embodiment.

In addition, the above-mentioned transceiver unit 2020 can also be a transceiver circuit (for example, it can include a sending circuit, or can also include a receiving circuit), and the processing unit 2020 can be a processing circuit.

It should be noted that the device in FIG9 can be the communication device (such as a terminal device or network device) in the aforementioned embodiments, or it can be a chip or chip system, such as a system on a chip (SoC). The transceiver unit can be an input/output circuit or a communication interface; the processing unit can be a processor, microprocessor, or integrated circuit integrated on the chip. This is not limited here.

FIG10 is a schematic diagram of another communication device 2100 provided in an embodiment of the present application. The device 2100 includes a processor 2110, which is coupled to a memory 2120. The memory 2120 is configured to store computer programs or instructions and/or data. The processor 2110 is configured to execute the computer programs or instructions stored in the memory 2120, or read data stored in the memory 2120, to perform the methods described in the above method embodiments.

Optionally, there are one or more processors 2110 .

Optionally, the memory 2120 is one or more.

Optionally, the memory 2120 is integrated with the processor 2110 or provided separately.

Optionally, as shown in Figure 10, the apparatus 2100 further includes a transceiver 2130, which is configured to receive and/or transmit signals. For example, the processor 2110 is configured to control the transceiver 2130 to receive and/or transmit signals.

As an example, the processor 2110 may have the function of the processing unit 2020 shown in FIG. 7 , the memory 2120 may have the function of a storage unit, and the transceiver 2130 may have the function of the transceiver unit 2020 shown in FIG. 7 .

As a solution, the device 2100 is used to implement the operations performed by a communication device (such as a terminal device or a network device) in the above various method embodiments.

For example, the processor 2110 is configured to execute computer programs or instructions stored in the memory 2120 to implement relevant operations of the communication device in the above various method embodiments.

In some implementations, when the device 2100 is a terminal device, the transceiver 2130 may include a transmitter, a receiver, a radio frequency circuit, an antenna, and input and output devices. The processor 2110 is mainly used to process communication protocols and communication data, as well as to control the terminal device, execute software programs, process software program data, etc. The memory 2120 is mainly used to store software programs and data. The radio frequency circuit is mainly used to convert baseband signals into radio frequency signals and process radio frequency signals. The antenna is mainly used to transmit and receive radio frequency signals in the form of electromagnetic waves. The input and output devices (for example, a touch screen, a display screen, a keyboard, etc.) are mainly used to receive data input by the user and output data to the user. It should be noted that some types of terminal devices may not have input and output devices.

When data needs to be sent, the processor performs baseband processing on the data to be transmitted and outputs the baseband signal to the RF circuit. The RF circuit then performs RF processing on the baseband signal and transmits it via the antenna in the form of electromagnetic waves. When data is sent to a terminal device, the RF circuit receives the RF signal via the antenna, converts it into a baseband signal, and outputs the baseband signal to the processor, which converts the baseband signal into data and processes it.

In other implementations, when the apparatus 2100 is a network device, such as a base station, the processor 2110 is primarily used for baseband processing, controlling the base station, etc.; the processor 2110 is typically the control center of the base station, used to control the base station to perform the processing operations on the network device side in the above-mentioned method embodiment. The memory 2120 is primarily used to store computer program code and data. The transceiver 2130 is primarily used for transmitting and receiving radio frequency signals and converting radio frequency signals into baseband signals; the transceiver 2130 may include an antenna and a radio frequency circuit (not shown in the figure), wherein the radio frequency circuit is primarily used for radio frequency processing.

In the embodiment of the present application, the antenna and radio frequency circuit with transceiver functions can be regarded as the transceiver module of the terminal device or network device, and the processor with processing function can be regarded as the processing module of the terminal device or network device.

In some implementations, the processor 2110 may also be referred to as a processing unit, a processing board, a processing module, a processing device, etc. The transceiver 2130 may also be referred to as a transceiver unit, a transceiver, a transceiver device, etc.

When the device 2100 is a chip, the chip includes a processor, memory, and a transceiver. The transceiver can be an input/output circuit or a communication interface; the processor can be a processing module, microprocessor, or integrated circuit integrated on the chip. The sending operation of the terminal device in the above method embodiment can be understood as the chip's output, and the receiving operation of the terminal device in the above method embodiment can be understood as the chip's input.

It should be understood that the processor mentioned in the embodiments of the present application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

It should also be understood that the memory mentioned in the embodiments of the present application can be a volatile memory and/or a non-volatile memory. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory can be a random access memory (RAM). For example, RAM can be used as an external cache. By way of example and not limitation, RAM includes the following forms: static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronized DRAM (SLDRAM), and direct rambus RAM (DR RAM).

It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, the memory (storage module) can be integrated into the processor.

It should also be noted that the memory described herein is intended to include, but is not limited to, these and any other suitable types of memory.

FIG11 is a schematic diagram of a chip system 2200 provided in accordance with an embodiment of the present application. The chip system 2200 (or processing system) includes a logic circuit 2210 and an input/output interface 2220.

Logic circuit 2210 may be a processing circuit within chip system 2200. Logic circuit 2210 may be coupled to a storage unit and invoke instructions within the storage unit, enabling chip system 2200 to implement the methods and functions of various embodiments of the present application. Input/output interface 2220 may be an input/output circuit within chip system 2200, outputting information processed by chip system 2200 or inputting data or signaling information to be processed into chip system 2200 for processing.

As a solution, the chip system 2200 is used to implement the operations performed by a communication device (such as a terminal device or a network device) in the above various method embodiments.

For example, the logic circuit 2210 is used to implement the processing-related operations performed by the communication device (such as a terminal device or a network device) in the above method embodiments; the input/output interface 2220 is used to implement the sending and/or receiving-related operations performed by the communication device (such as a terminal device or a network device) in the above method embodiments.

An embodiment of the present application further provides a computer-readable storage medium on which computer instructions are stored for implementing the methods executed by a communication device (such as a terminal device or a network device) in the above-mentioned method embodiments.

For example, when the computer program is executed by a computer, the computer can implement the methods performed by the communication device (such as terminal equipment) in each embodiment of the above method.

An embodiment of the present application further provides a computer program product comprising instructions, which, when executed by a computer, implement the methods performed by a communication device (such as a terminal device or a network device) in the above-mentioned method embodiments.

Those skilled in the art can clearly understand that, for the sake of convenience and brevity of description, the explanation and beneficial effects of the relevant contents in any of the communication devices provided above can refer to the corresponding method embodiments provided above, and will not be repeated here.

In order to facilitate understanding of the embodiments of the present application, the following points are first explained.

1. Unless otherwise specified, “at least one” means one or more, and “more than one” means two or more.

2. Unless otherwise specified or there is no logical conflict, the terms and/or descriptions between different embodiments of this application are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments based on their internal logical relationships.

3. The various numerical numbers involved in this application are only used for the convenience of description and are not used to limit the scope of protection of this application. The size of the serial numbers involved in this application does not mean the order of execution. The order of execution of each process should be determined by its function and internal logic. For example, the terms "first", "second", "third", "fourth" and other various terminology labels (if any) in the specification and claims and drawings of this application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. Among them, the data used in this way can be interchangeable where appropriate, so that the embodiments described here can be implemented in an order other than what is illustrated or described here.

At the same time, any embodiment or design described in this application as "exemplary" or "for example" should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner to facilitate understanding.

4. The terms "comprise" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product or apparatus.

5. In this application, "used to indicate" can be understood as "enabling," and "enabling" can include direct enabling and indirect enabling. When describing that certain information is used to enable A, it can include that the information directly enables A or indirectly enables A, and does not necessarily mean that the information contains A.

The information enabled by the information is called information to be enabled. In the specific implementation process, there are many ways to enable the enabled information, such as but not limited to, directly enabling the information to be enabled, such as the information to be enabled itself or the index of the information to be enabled. The information to be enabled can also be indirectly enabled by enabling other information, wherein there is an association between the other information and the information to be enabled. It is also possible to enable only a part of the information to be enabled, while the other parts of the information to be enabled are known or agreed in advance. For example, it is also possible to enable specific information with the help of the arrangement order of each piece of information agreed in advance (such as specified in the protocol), thereby reducing the enabling overhead to a certain extent. At the same time, it is also possible to identify the common parts of each piece of information and enable them uniformly to reduce the enabling overhead caused by enabling the same information separately.

6. In this application, "pre-configuration" may include pre-definition, such as protocol definition. "Pre-definition" may be implemented by pre-storing corresponding codes, tables, or other methods that can be used to indicate relevant information in a device (e.g., including each network element). This application does not limit the specific implementation method.

7. "Storage" or "storage" as used in this application may refer to storage in one or more memories. The one or more memories may be provided separately or integrated into an encoder or decoder, a processor, or a communication device. The one or more memories may also have some provided separately and some integrated into a decoder, processor, or communication device. The type of memory may be any form of storage medium and is not limited thereto.

8. The “protocol” referred to in this application may refer to a standard protocol in the field of communications, for example, it may include the ^fourth generation (4G) network, the ^fifth generation (5G) network protocol, the new radio (NR) protocol, the 5.5G network protocol, the ^sixth generation (6G) network protocol and related protocols used in future communication systems, and this application does not limit this.

9. The arrows or boxes indicated by dotted lines in the schematic diagrams in the accompanying drawings of this application specification represent optional steps or optional modules.

10. Unless otherwise specified, “/” indicates that the objects associated with each other are in an “or” relationship. For example, A/B can mean A or B. “And/or” in this application is only a description of the association relationship between the associated objects, indicating that there can be three relationships. For example, A and/or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

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

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

In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

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

As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims (17)

A communication method, comprising: The second network device sends a first message, where the first message includes a first information element, where the first information element is used to indicate whether a first-type terminal device is allowed to access the second network device, where the first-type terminal device includes a store-and-forward terminal device; The second network device receives first request information from a terminal device, where the first request information is used to request access to the second network device, the terminal device is the first type of terminal device, and the second network device is a non-terrestrial network device. The method according to claim 1 is characterized in that the first message is a system information block SIB. The method according to claim 1 or 2 is characterized in that the first information element is used to indicate that the first type of terminal device is allowed to access the second network device, and the second network device operates in a store-and-forward mode. The method according to any one of claims 1 to 3, characterized in that the first message further includes a second information element and/or a third information element, the second information element is used to indicate whether the second type of terminal device is allowed to access the second network device, and the third information element is used to indicate whether the third type of terminal device is allowed to access the second network device. Among them, the second type of terminal equipment includes ground network terminal equipment, and the third type of terminal equipment includes non-ground network terminal equipment. The method according to claim 4 is characterized in that, when the second network device is in store-and-forward mode, the third information element is a third value, and the third information element is used to indicate that the third type of terminal device is denied access to the second network device. A communication method, comprising: The terminal device receives a first message, where the first message includes a first information element, where the first information element is used to indicate whether a first type of terminal device is allowed to access the second network device, where the first type of terminal device includes a store-and-forward terminal device; When the first information element is used to indicate that a first type of terminal device is allowed to access a second network device, and the terminal device is the first type of terminal device, the terminal device sends a first request information to the second network device, and the first request information is used to request access to the second network device, wherein the second network device is a non-terrestrial network device. The method according to claim 6 is characterized in that the first message further includes a second information element and/or a third information element, the second information element is used to indicate whether a second type of terminal device is allowed to access the second network device, and the third information element is used to indicate whether a third type of terminal device is allowed to access the second network device, wherein the second type of terminal device includes a terrestrial network terminal device, and the third type of terminal device includes a non-terrestrial network terminal device. The method according to claim 7, wherein the first message includes the second information element and the third information element, When the terminal device is the first type of terminal device, the terminal device ignores the values of the second information element and the third information element in the first message, and the terminal device determines whether to send the first request information to the second network device based on the first information element. The method according to claim 7, wherein the first message includes the second information element and the third information element, When the terminal device is not the first type of terminal device and is the third type of terminal device, the terminal device ignores the first information element and the second information element, and the terminal device determines whether to send the first request information to the second network device based on the third information element. The method according to claim 7, wherein the first message includes the second information element and the third information element, When the terminal is not the first type of terminal device and the terminal device is the second type of terminal device, the terminal device ignores the first information element and the third information element, and the terminal device determines whether to send the first request information to the second network device based on the second information element. A communication device, characterized by comprising a module for executing the method according to any one of claims 1 to 5, or for executing the method according to any one of claims 6 to 10. A communication device, characterized in that it includes a transceiver unit and a processing unit, wherein the transceiver unit and the processing unit are used to execute the method according to any one of claims 1 to 5, or to execute the method according to any one of claims 6 to 10. A communication device, characterized in that it includes at least one processor, the at least one processor is coupled to at least one memory, and the at least one processor is used to execute a computer program or instruction stored in the at least one memory so that the communication device performs the method according to any one of claims 1 to 5, or performs the method according to any one of claims 6 to 10. A communication system, characterized by comprising a terminal device and a network device; The network device is used to perform the communication method according to any one of claims 1 to 5; The terminal device is configured to execute the communication method according to any one of claims 6 to 10. A computer-readable storage medium, characterized in that instructions or program codes are stored thereon, and when the instructions or program codes are executed by a processor, the processor implements the method according to any one of claims 1 to 5, or the method according to any one of claims 6 to 10. A chip, characterized in that the chip includes a processor and a communication interface, the communication interface is used to send information to other communication devices other than the communication device including the chip and/or receive information from the other communication devices, and the processor is used to execute the method as described in any one of claims 1 to 5, or to execute the method as described in any one of claims 6 to 10. A computer program product, characterized in that the computer program product comprises a computer program or instructions for executing the method according to any one of claims 1 to 10.