Communication method and communication apparatus

Abstract

This application relates to the field of communications, specifically to a communication method and a communication device. In traditional cell handover processes, the source cell needs to obtain initial information for handover from the target cell. However, when the target cell is a weakly cooperative cell, the source cell takes a considerable amount of time to obtain this initial information. In this application, the source cell or the core network stores the initial information. During cell handover, the source cell first determines whether the target cell meets a first condition. If the target cell meets the first condition, the source cell obtains the initial information from the core network or locally, and no longer obtains it from the target cell, thereby reducing the mobility interruption time for the terminal when handover between different types of cells.

Description

Technical Field

[0001] This application relates to the field of communications, specifically to a communication method and a communication device. Background Technology

[0002] In mobile communication systems, a cell can be viewed as a wireless signal coverage area identified by a physical cell identifier (PCI) or a cell global identifier (CGI). The coverage area of ​​each network device (e.g., a base station) can be divided into one or more cells. A terminal can move from one cell to another and communicate through the access service provided by the other cell; this process is called cell handover. The cell the terminal accesses before the handover can be called the source cell, and the cell the terminal accesses after the handover can be called the target cell.

[0003] As mobile communication systems are used in increasingly diverse applications, cell handover scenarios are becoming more complex. The source and destination cells may belong to different types of cells; for example, a terminal may handover from a terrestrial network (TN) cell to a non-terrestrial network (NTN) cell, or from an NTN cell to a TN cell. Reducing the mobility interruption time during handovers between different cell types is a problem that needs to be addressed. Summary of the Invention

[0004] Embodiments of this application provide a communication method, communication device, communication system, computer-readable storage medium, and computer program product that can reduce mobility interruption time when handing over between different types of cells of a terminal.

[0005] In a first aspect, embodiments of this application provide a communication method applied to a source cell, wherein the source cell may be provided by a network device (e.g., a base station) or a module (e.g., a circuit or a chip) of the network device. The following description uses a source cell as an example. The method includes: determining first information when a target cell meets a first condition, wherein the first information is information configured by the core network for cell handover, or the first information is pre-configured information for cell handover; and sending the first information to a terminal.

[0006] The target cell satisfies the first condition, including at least one of the following: the communication delay between the target cell and the source cell is greater than or equal to the first threshold, or the cell bandwidth of the target cell is less than or equal to the second threshold, or the transmission path length between the target cell and the source cell is greater than or equal to the third threshold, or the communication interface between the target cell and the source cell is expired or does not exist.

[0007] The target cell is a TN cell and the source cell is an NTN cell; or the target cell is an NTN cell and the source cell is a TN cell; or the target cell and the source cell are two NTN cells with different orbits (or altitudes).

[0008] During cell handover, the source cell needs to send initial handover information to the terminal. In traditional handover processes, the source cell obtains this initial information from the target cell. However, even when the target cell meets certain conditions, the source cell may take a considerable amount of time to obtain this information; for example, the initial information might need to pass through one or more core networks to be transmitted from the target cell to the source cell. In this embodiment, the source cell or the core network stores the initial information. During cell handover, the source cell first determines whether the target cell meets the initial conditions. If the target cell does meet the initial conditions, the source cell obtains the initial information from the core network or locally, instead of directly from the target cell, thereby reducing the mobility interruption time for the terminal when handover between different types of cells.

[0009] In an optional implementation of the first aspect, the first information includes resource information, which is used to configure or activate the area-specific random access resources corresponding to the target cell, wherein;

[0010] The area-dedicated random access resources corresponding to the target cell are related to the transmission method of the timing advance (TA) of the target cell. Wherein, if the target cell meets the first condition, the area-dedicated random access resources are used to instruct the TA to be transmitted directly from the target cell to the terminal; if the target cell does not meet the first condition, the area-dedicated random access resources are used to instruct the TA to be transmitted to the terminal through the source cell; and / or;

[0011] The area-specific random access resources corresponding to the target cell are valid when the terminal is located in the target area, where the target area includes the overlapping area between the target cell and the source cell (i.e., the overlapping part of the geographical area covered by the wireless signal).

[0012] TA (Transmission Target) is typically carried within a random access response (RAR). Therefore, "TA transmission method" can also be referred to as "RAR transmission method." Furthermore, "TA (or RAR) transmission method" and "TA (or RAR) reception method" are equivalent descriptions. When using "TA (or RAR) reception method," "Region-specific random access resources are used to instruct the TA to be transmitted directly from the target cell to the terminal" is equivalent to "Region-specific random access resources are used to instruct the terminal to receive the TA (or RAR) directly from the target cell," and "Region-specific random access resources are used to instruct the TA to be transmitted through the source cell to the terminal" is equivalent to "Region-specific random access resources are used to instruct the terminal to receive the TA (or RAR) through the source cell."

[0013] When the target cell meets the first condition, the latency between the target cell and the source cell is relatively large. Sending the TA directly from the target cell to the terminal can reduce the TA transmission latency. When the target cell does not meet the first condition, the latency between the target cell and the source cell is relatively small. Sending the TA from the source cell to the terminal reuses the existing TA transmission method, which improves the forward compatibility of this embodiment while meeting the mobility interruption time requirements of cell handover, and can also improve the communication rate during cell handover. Therefore, by configuring different methods for sending TA using the area-specific random access resource (ISPR) indicator, different scenarios can be flexibly adapted. In addition, configuring the ISPR to be effective only when the terminal is located in the target area can avoid the terminal occupying the ISPR for a long time, thereby improving the utilization rate of the ISPR.

[0014] In an optional implementation of the first aspect, the first information includes time information, which is used to configure or activate a first time period, which is used for the terminal to perform uplink and downlink synchronization with the target cell.

[0015] The terminal can determine the first time period based on the time information contained in the first information, and complete uplink and downlink synchronization with the target cell within the first time period. Since the first information is sent to the terminal before the cell handover command, the terminal can complete uplink and downlink synchronization before cell handover, thereby reducing the mobility interruption time during cell handover.

[0016] In an alternative implementation of the first aspect, the time information includes one or more of the length of the first time period, the period, and the offset.

[0017] The source cell can flexibly configure or activate the first time period by using one or more parameters of the first time period length, period, and offset.

[0018] In an optional implementation of the first aspect, the method further includes: sending second information to the terminal, the second information being used to indicate the transmission mode (or reception mode) of the TA, the TA being used by the terminal to perform uplink synchronization with the target cell.

[0019] The methods for transmitting a TA include: if the target cell does not meet the first condition, the target cell directly transmits the TA to the terminal; or, if the target cell meets the first condition, the target cell transmits the TA to the terminal through the source cell. Similarly, the methods for receiving a TA include: if the target cell does not meet the first condition, the TA is received directly from the target cell; or, if the target cell meets the first condition, the TA is received from the target cell through the source cell.

[0020] When the target cell meets the first condition, the latency between the target cell and the source cell is relatively large. Sending the TA directly from the target cell to the terminal can reduce the TA transmission latency. When the target cell does not meet the first condition, the latency between the target cell and the source cell is relatively small. Sending the TA from the source cell to the terminal reuses the existing TA transmission method, which can improve the forward compatibility of this embodiment and also improve the communication rate during cell handover. Therefore, by indicating the TA transmission method through the second information, different scenarios can be flexibly adapted.

[0021] In an optional implementation of the first aspect, the method further includes: receiving a TA from a target cell, wherein the area-specific random access resource corresponding to the target cell is absent or inactive, or the target cell does not detect the area-specific preamble of the terminal; and sending a TA to the terminal.

[0022] If the area-specific random access resource corresponding to the target cell is absent or ineffective, the terminal may be far away from the target cell. After the target cell determines the TA (which is determined by the target cell based on non-area-specific random access resources), it can send the TA to the terminal through the source cell, which can improve the success rate of TA transmission.

[0023] In an optional implementation of the first aspect, the method further includes: sending third information to the terminal, the third information including a cell handover command and context information or status information for instructing the terminal whether to send cell handover to the target cell.

[0024] The third piece of information can be a cell handover command, or it can be a message containing a cell handover command. The cell handover command is used to instruct the terminal to perform a cell handover.

[0025] In some cases, such as when the transmission path between the target cell and the source cell is long, and the target cell supports receiving context information or status information from the terminal before the handover is complete, the third information can instruct the terminal to send the context information or status information directly to the target cell. This eliminates the need for forwarding from the source cell, reducing mobility interruption time and handover signaling overhead during cell handover. In other cases, such as when the target cell does not support receiving context information or status information from the terminal before the handover is complete, the third information can instruct the terminal to send the context information or status information to the target cell through the source cell, thereby improving the success rate of cell handover.

[0026] In an optional implementation of the first aspect, the method further includes: sending a fourth message to the core network before sending the third message to the terminal, wherein the fourth message requests an update to the terminal's transmission path and context information (or, status information).

[0027] In this embodiment, the core network can receive the fourth information before the terminal performs cell handover. In this way, the core network can reserve resources for updating the transmission path and context information and advance the transmission time, thereby reducing the mobile interruption time during cell handover.

[0028] In an optional implementation of the first aspect, the interval between the transmission time of the third information and the transmission time of the fourth information is configured by the core network.

[0029] In an optional implementation of the first aspect, the method further includes: receiving type information from a terminal, the type information indicating whether the target cell is a TN cell or an NTN cell; and determining whether the target cell meets a first condition based on the type information.

[0030] When the target cell type differs from the source cell type, the source cell can directly determine that the target cell meets the first condition. Therefore, the source cell does not need to maintain a cell state list (which indicates whether the target cell meets the first condition), thus reducing the source cell's resource overhead.

[0031] Secondly, embodiments of this application provide a communication method applied to a terminal. Optionally, the method can be executed by the terminal or its modules (e.g., circuits or chips). The following description uses a terminal as an example. The method includes: sending type information to a source cell, the type information indicating whether the target cell is a TN or NTN cell; receiving first information from the source cell, wherein the source cell and the target cell have different types, the first information being core network-configured information for cell handover, or the first information being pre-configured information for cell handover in the source cell; and performing cell handover based on the first information.

[0032] During cell handover, the source cell needs to send first information for cell handover to the terminal. In traditional handover, the source cell obtains this first information from the target cell. However, even when the target cell meets a first condition, the source cell may take a considerable amount of time to obtain the first information from the target cell; for example, the first information may need to pass through one or more core networks to be transmitted from the target cell to the source cell. In this embodiment, the terminal indicates the type of the target cell (i.e., TN cell or NTN cell) to the source cell through type information. The source cell can then determine the method of obtaining the first information based on the type of the target cell. When the source cell and target cell are of different types, the source cell can assume that the target cell meets the first condition described in the first aspect and no longer obtain the first information from the target cell. Instead, it obtains the first information from the core network or locally and then sends it to the terminal, thereby reducing the mobility interruption time when the terminal hands over between different types of cells.

[0033] In an optional implementation of the second aspect, the first information includes resource information, which is used to configure or activate the area-specific random access resources corresponding to the target cell.

[0034] The area-dedicated random access resource corresponding to the target cell is related to the transmission method of the target cell's TA. When the target cell meets the first condition, the area-dedicated random access resource is used to instruct the TA to be transmitted directly from the target cell to the terminal. When the target cell does not meet the first condition, the area-dedicated random access resource is used to instruct the TA to be transmitted to the terminal through the source cell. And / or, the area-dedicated random access resource corresponding to the target cell is valid when the terminal is located within the target area, wherein the target area includes the overlapping area of ​​the target cell and the source cell.

[0035] The target cell satisfies the first condition, including at least one of the following: the communication delay between the target cell and the source cell is greater than or equal to a first threshold, or the cell bandwidth of the target cell is less than or equal to a second threshold, or the transmission path length between the target cell and the source cell is greater than or equal to a third threshold, or the communication interface between the target cell and the source cell is expired or does not exist.

[0036] TA (Transmission Target) is typically carried within RAR (Receiving Target), therefore, "TA transmission method" can also be called "RAR transmission method". Furthermore, "TA (or RAR) transmission method" and "TA (or RAR) reception method" are equivalent descriptions. When using "TA (or RAR) reception method" as a description, "Region-dedicated random access resources are used to instruct the TA to be transmitted directly from the target cell to the terminal" is equivalent to "Region-dedicated random access resources are used to instruct the terminal to receive the TA (or RAR) directly from the target cell", and "Region-dedicated random access resources are used to instruct the TA to be transmitted through the source cell to the terminal" is equivalent to "Region-dedicated random access resources are used to instruct the terminal to receive the TA (or RAR) through the source cell".

[0037] When the target cell meets the first condition, the latency between the target cell and the source cell is relatively large. Sending the TA directly from the target cell to the terminal can reduce the TA transmission latency. When the target cell does not meet the first condition, the latency between the target cell and the source cell is relatively small. Sending the TA from the source cell to the terminal reuses the existing TA transmission method, which improves the forward compatibility of this embodiment while meeting the mobility interruption time requirements of cell handover, and can also improve the communication rate during cell handover. Therefore, by configuring different methods for sending TA using the area-specific random access resource (ISPR) indicator, different scenarios can be flexibly adapted. In addition, configuring the ISPR to be effective only when the terminal is located in the target area can avoid the terminal occupying the ISPR for a long time, thereby improving the utilization rate of the ISPR.

[0038] In an optional implementation of the second aspect, the first information includes time information used to configure or activate a first time period, and the method further includes: performing uplink and downlink synchronization with the target cell during the first time period.

[0039] The terminal can determine the first time period based on the time information contained in the first information, and complete uplink and downlink synchronization with the target cell within the first time period. Since the first information is sent to the terminal before the cell handover command, the terminal can complete uplink and downlink synchronization before cell handover, thereby reducing the mobility interruption time during cell handover.

[0040] In an alternative implementation of the second aspect, the time information includes one or more of the length, period, and offset of the first time period.

[0041] The source cell can flexibly configure or activate the first time period by using one or more parameters of the first time period length, period, and offset.

[0042] In an optional implementation of the second aspect, the method further includes: receiving second information from a source cell, the second information indicating the transmission mode (or reception mode) of the TA; receiving the TA according to the second information; and performing uplink synchronization and downlink synchronization with a target cell during a first time period, including: performing uplink synchronization with the target cell according to the TA during the first time period.

[0043] The methods for transmitting a TA include: if the target cell does not meet the first condition, the target cell directly transmits the TA to the terminal; or, if the target cell meets the first condition, the target cell transmits the TA to the terminal through the source cell. Similarly, the methods for receiving a TA include: if the target cell does not meet the first condition, the TA is received directly from the target cell; or, if the target cell meets the first condition, the TA is received from the target cell through the source cell.

[0044] When the target cell meets the first condition, the latency between the target cell and the source cell is relatively large. Sending the TA directly from the target cell to the terminal can reduce the TA transmission latency. When the target cell does not meet the first condition, the latency between the target cell and the source cell is relatively small. Sending the TA from the source cell to the terminal reuses the existing TA transmission method, which can improve the forward compatibility of this embodiment and also improve the communication rate during cell handover. Therefore, by indicating the TA transmission method through the second information, different scenarios can be flexibly adapted.

[0045] In an optional implementation of the second aspect, receiving a TA based on the second information includes: receiving a TA from a target cell based on the second information.

[0046] When the area-specific random access resources corresponding to the target cell are in effect, the terminal can directly receive the TA from the target cell. Compared with the method of relaying the TA through the source cell, this embodiment reduces the transmission latency of the TA. The terminal can perform uplink synchronization with the target cell as soon as possible based on the TA, thereby reducing the mobile interruption time during cell handover.

[0047] In an optional implementation of the second aspect, the method further includes: receiving third information from the source cell, the third information including a cell handover command and context information or status information for instructing the terminal whether to send the cell handover to the target cell; and sending the context information or status information according to the third information.

[0048] The third piece of information can be a cell handover command, or it can be a message containing a cell handover command. The cell handover command is used to instruct the terminal to perform a cell handover.

[0049] In some cases, such as when the transmission path between the target cell and the source cell is long, and the target cell supports receiving context information or status information from the terminal before the handover is complete, the third information can instruct the terminal to send the context information or status information directly to the target cell. This eliminates the need for forwarding from the source cell, reducing mobility interruption time and handover signaling overhead during cell handover. In other cases, such as when the target cell does not support receiving context information or status information from the terminal before the handover is complete, the third information can instruct the terminal to send the context information or status information to the target cell through the source cell, thereby improving the success rate of cell handover.

[0050] In an optional implementation of the second aspect, the method further includes: sending fifth information to the target cell, the fifth information indicating that cell handover has been completed, the fifth information including the terminal's context information or status information.

[0051] Compared to the method of the terminal sending context information or status information to the target cell through the source cell, the method of the terminal sending context information or status information directly to the target cell reduces the transmission latency of context information or status information. The core network can update the terminal's transmission path and context information (or status information) as soon as possible based on the context information or status information, thereby reducing the mobile interruption time during cell handover.

[0052] Thirdly, embodiments of this application provide a communication method applied to a target cell, wherein the target cell can be provided by a network device (e.g., a base station) or a module (e.g., a circuit or a chip) of the network device. The following description uses a target cell as an example. The method includes: when the target cell meets a first condition, receiving a preamble from a terminal via a regional dedicated random access resource, the preamble instructing the target cell to directly send a TA to the terminal; and sending a TA to the terminal based on the preamble, the TA being used for uplink synchronization between the terminal and the target cell.

[0053] The target cell satisfies the first condition, including at least one of the following: the communication delay between the target cell and the source cell is greater than or equal to the first threshold, or the cell bandwidth of the target cell is less than or equal to the second threshold, or the transmission path length between the target cell and the source cell is greater than or equal to the third threshold, or the communication interface between the target cell and the source cell is expired or does not exist.

[0054] The target cell is a TN cell and the source cell is an NTN cell; or the target cell is an NTN cell and the source cell is a TN cell; or the target cell and the source cell are two NTN cells with different orbits (or altitudes).

[0055] If the target cell meets the first condition, the time delay between the target cell and the source cell is relatively large. Sending the TA directly from the target cell to the terminal can reduce the transmission delay of the TA. The terminal can perform uplink synchronization with the target cell as soon as possible based on the TA, thereby reducing the mobile interruption time during cell handover.

[0056] In an optional implementation of the third aspect, the method further includes: receiving fifth information from the terminal, the fifth information indicating that cell handover has been completed, the fifth information including context information or status information of the terminal; and sending the context information or status information of the terminal to the core network.

[0057] Compared to the method of the terminal sending context information or status information to the target cell through the source cell, the method of the terminal sending context information or status information directly to the target cell reduces the transmission latency of context information or status information. The core network can update the terminal's transmission path and context information (or status information) as soon as possible based on the context information or status information, thereby reducing the mobile interruption time during cell handover.

[0058] Fourthly, embodiments of this application provide a communication method applied to a core network. The core network can be provided by a network device (e.g., a server) or a module of the network device (e.g., a circuit or a chip). The following description uses a core network as an example. The method includes: receiving a request message from a source cell, the request message requesting first information for cell handover, the first information including resource information and / or time information, the resource information being used to configure or activate area-specific random access resources corresponding to the target cell, and the time information being used to configure or activate a first time period, the first time period being used for uplink and downlink synchronization between the terminal and the target cell; and sending the first information to the source cell.

[0059] During cell handover, the source cell needs to send initial handover information to the terminal. In traditional handover processes, the source cell obtains this initial information from the target cell. However, even when the target cell meets certain conditions, the source cell may take a considerable amount of time to obtain this initial information; for example, the information might need to pass through one or more core networks to be transmitted from the target cell to the source cell. In this embodiment, the core network stores the initial information. During handover, the source cell first determines whether the target cell meets the initial conditions. If the target cell does meet the conditions, the source cell obtains the initial information from the core network instead of from the target cell, thereby reducing the mobility interruption time during handover between TN and NTN cells.

[0060] Furthermore, when the first information includes time information, the terminal can complete uplink and downlink synchronization with the target cell within the first time period corresponding to the time information. Since the first information is sent to the terminal before the cell handover command, the terminal can complete uplink and downlink synchronization before cell handover, thereby reducing the mobility interruption time during cell handover.

[0061] In an optional implementation of the fourth aspect, the area-dedicated random access resource corresponding to the target cell is related to the transmission method of the target cell's TA, wherein, if the target cell meets the first condition, the area-dedicated random access resource is used to instruct the TA to be transmitted directly from the target cell to the terminal; if the target cell does not meet the first condition, the area-dedicated random access resource is used to instruct the TA to be transmitted to the terminal through the source cell; and / or,

[0062] The area-specific random access resources corresponding to the target cell are valid when the terminal is located in the target area, where the target area includes the overlapping area between the target cell and the source cell.

[0063] TA (Transmission Target) is typically carried within RAR (Receiving Target), therefore, "TA transmission method" can also be called "RAR transmission method". Furthermore, "TA (or RAR) transmission method" and "TA (or RAR) reception method" are equivalent descriptions. When using "TA (or RAR) reception method" as a description, "Region-dedicated random access resources are used to instruct the TA to be transmitted directly from the target cell to the terminal" is equivalent to "Region-dedicated random access resources are used to instruct the terminal to receive the TA (or RAR) directly from the target cell", and "Region-dedicated random access resources are used to instruct the TA to be transmitted through the source cell to the terminal" is equivalent to "Region-dedicated random access resources are used to instruct the terminal to receive the TA (or RAR) through the source cell".

[0064] When the target cell meets the first condition, the latency between the target cell and the source cell is relatively large. Sending the TA directly from the target cell to the terminal can reduce the TA transmission latency. When the target cell does not meet the first condition, the latency between the target cell and the source cell is relatively small. Sending the TA from the source cell to the terminal reuses the existing TA transmission method, which improves the forward compatibility of this embodiment while meeting the mobility interruption time requirements of cell handover, and can also improve the communication rate during cell handover. Therefore, by configuring different methods for sending TA using the area-specific random access resource (ISPR) indicator, different scenarios can be flexibly adapted. In addition, configuring the ISPR to be effective only when the terminal is located in the target area can avoid the terminal occupying the ISPR for a long time, thereby improving the utilization rate of the ISPR.

[0065] In an alternative implementation of the fourth aspect, the time information includes one or more of the length, period, and offset of the first time period.

[0066] The core network can flexibly configure or activate the first time period by using one or more parameters, including the length, period, and offset of the first time period.

[0067] In an optional implementation of the fourth aspect, the method further includes: receiving fourth information from the source cell, the fourth information requesting an update of the terminal's transmission path and context information (or, status information), the interval between the transmission time of the third information and the transmission time of the fourth information being configured by the core network, and the third information including a cell handover command sent by the source cell to the terminal.

[0068] After configuring the above intervals, the core network can receive the fourth information before the terminal performs cell handover. In this way, the core network can reserve resources for updating transmission path and context information and advance the transmission time, thereby reducing the mobility interruption time during cell handover.

[0069] In an optional implementation of the fourth aspect, the method further includes: receiving context information or status information of the terminal from the target cell.

[0070] In this embodiment, the terminal directly sends context information or status information to the target cell, and the core network receives the terminal's context information or status information from the target cell. Compared to the method where the terminal sends context information or status information to the target cell through the source cell, and then the target cell forwards the context information or status information to the core network, in this embodiment, the core network can update the terminal's transmission path and context information (or status information) as quickly as possible based on the context information or status information, thereby reducing the mobility interruption time during cell handover.

[0071] Fifthly, embodiments of this application provide a communication method applied to a source cell, wherein the source cell can be provided by a network device (e.g., a base station) or a module (e.g., a circuit or a chip) of the network device. The following description uses a source cell as an example. The method includes:

[0072] If the target cell meets the first condition, a sixth message is sent to the terminal. The sixth message is used to indicate the activation of the target cell's protocol stack. The target cell's protocol stack includes the physical layer, media access control layer, radio link control layer, packet data aggregation protocol layer, service data adaptation protocol layer, and radio resource control layer. The target cell is a TN cell and the source cell is an NTN cell; or, the target cell is an NTN cell and the source cell is a TN cell; or, the target cell and the source cell are two NTN cells on different tracks (or at different altitudes).

[0073] The target cell satisfies the first condition, including at least one of the following: the communication delay between the target cell and the source cell is greater than or equal to a first threshold, or the cell bandwidth of the target cell is less than or equal to a second threshold, or the transmission path length between the target cell and the source cell is greater than or equal to a third threshold, or the communication interface between the target cell and the source cell is expired or does not exist.

[0074] Optionally, "activating the protocol stack of the target cell" can also be referred to as "activating the state of the radio resource control layer of the target cell".

[0075] In traditional cell handover, the terminal maintains both a complete protocol stack and an incomplete protocol stack (including the physical layer, media access control layer, and radio link control layer). The complete protocol stack uses parameters from the source cell, while the incomplete stack uses parameters from the target cell. The incomplete protocol stack can only be used to access the target cell and cannot be used to send or receive application layer data. After the handover is complete, the terminal updates the parameters of the complete protocol stack to those of the target cell before establishing a Protocol Data Unit (PDU) session with the target cell based on the complete protocol stack. This PDU session is then used to send or receive application layer data. When the source and target cells are of different types, the transmission delay between them is relatively long, requiring the terminal to spend considerable time establishing a PDU session with the target cell based on the complete protocol stack. This results in a prolonged mobile interruption during the handover.

[0076] In this embodiment, the terminal is pre-configured (either by the source base station or the core network) with two complete protocol stacks. One protocol stack applies the parameters of the source cell, while the other protocol stack applies the parameters of the target cell during cell handover (i.e., the target cell's protocol stack is activated based on the indication of the sixth information). In this way, the terminal can establish a PDU session with the target cell based on the complete protocol stack before the cell handover is completed, and send or receive application layer data based on this PDU session, thereby reducing the mobility interruption time during cell handover.

[0077] In an optional implementation of the fifth aspect, the sixth information is used to indicate the activation of the protocol stack of the target cell, including: the sixth information is used to indicate the activation of the protocol stack of the target cell in a first time period and / or a first geographical area.

[0078] The first time period can be a time period related to cell handover (e.g., the time period during which the terminal performs uplink and / or downlink synchronization with the target cell), and the first geographical region can be a region related to cell handover (e.g., the overlapping area of ​​the source cell and the target cell, or the area where the channel quality of the target cell meets the transmission requirements). Activating the protocol stack of the target cell in the first time period and / or the first geographical region enables activation of the protocol stack based on cell handover requirements, thereby avoiding the resource waste caused by the terminal activating the protocol stack of the target cell in advance.

[0079] In an optional implementation of the fifth aspect, the method further includes: sending seventh information to the core network, the seventh information being used to instruct the core network to determine the data offloading method for the terminal; and sending eighth information to the target cell, the eighth information being used to instruct the core network to determine the data offloading method for the terminal. Here, data offloading can also be referred to as data forwarding.

[0080] In traditional handover processes, the source cell is responsible for controlling data offloading of the terminal. That is, after the terminal sends data to the source cell, the source cell determines the data transmission path. The source cell can generate control signaling related to data offloading and send this control signaling to the target cell. When the source and target cells are of different types, or when the target cell meets a first condition, the transmission delay of the control signaling related to data offloading is relatively long. For example, the control signaling and / or service data may need to pass through one or more core networks to reach the target cell from the source cell. In this embodiment, the core network is responsible for the terminal's data offloading. The control signaling and / or service data generated by the core network have a shorter latency to reach the target cell, thereby reducing the data forwarding latency during cell handover.

[0081] Sixthly, embodiments of this application provide a communication method applied to a terminal. Optionally, the method can be executed by the terminal or a module of the terminal (e.g., a circuit or a chip). The following description uses a terminal as an example. The method includes: receiving sixth information from a source cell, the sixth information indicating the activation of the protocol stack of a target cell; activating the protocol stack of the target cell according to the sixth information; wherein the protocol stack of the target cell includes a physical layer, a media access control layer, a radio link control layer, a packet data convergence protocol layer, a service data adaptation protocol layer, and a radio resource control layer; wherein the target cell is a TN cell and the source cell is an NTN cell; or, the target cell is an NTN cell and the source cell is a TN cell; or, the target cell and the source cell are two NTN cells at different orbits (or altitudes).

[0082] Optionally, "activating the protocol stack of the target cell" can also be referred to as "activating the state of the radio resource control layer of the target cell".

[0083] In traditional cell handover processes, a complete protocol stack and an incomplete protocol stack (including the physical layer, media access control layer, and radio link control layer) are maintained. The complete protocol stack uses the parameters of the source cell, while the incomplete protocol stack uses the parameters of the target cell. The incomplete protocol stack can only be used to access the target cell and cannot be used to send or receive application layer data. After the cell handover is completed, the terminal updates the parameters of the complete protocol stack to those of the target cell before establishing a PDU session based on the complete protocol stack with the target cell. This PDU session is then used to send or receive application layer data. When the source and target cells are of different types, the transmission delay between them is relatively long, requiring the terminal to spend a considerable amount of time establishing a PDU session based on the complete protocol stack with the target cell. This results in a prolonged mobility interruption during cell handover.

[0084] In this embodiment, the terminal is pre-configured (either by the source base station or the core network) with two complete protocol stacks. One protocol stack applies the parameters of the source cell, while the other protocol stack applies the parameters of the target cell during cell handover (i.e., the target cell's protocol stack is activated based on the indication of the sixth information). In this way, the terminal can establish a PDU session with the target cell based on the complete protocol stack before the cell handover is completed, and send or receive application layer data based on this PDU session, thereby reducing the mobility interruption time during cell handover.

[0085] In an optional implementation of the sixth aspect, activating the protocol stack of the target cell according to the sixth information includes: activating the protocol stack of the target cell in a first time period and / or a first geographical region according to the sixth information.

[0086] The first time period can be a time period related to cell handover (e.g., the time period during which the terminal performs uplink and / or downlink synchronization with the target cell), and the first geographical region can be a region related to cell handover (e.g., the overlapping area of ​​the source cell and the target cell, or the area where the channel quality of the target cell meets the transmission requirements). Activating the protocol stack of the target cell in the first time period and / or the first geographical region enables activation of the protocol stack based on cell handover requirements, thereby avoiding the resource waste caused by the terminal activating the protocol stack of the target cell in advance.

[0087] In an optional implementation of the sixth aspect, the method further includes: after the cell handover is completed, deactivating the protocol stack of the source cell.

[0088] Optionally, "deactivating the protocol stack of the source cell" can also be referred to as "deactivating the state of the radio resource control layer of the source cell". For example, after deactivation, the state of the radio resource control layer of the source cell can be idle or inactive.

[0089] After the source cell's protocol stack is deactivated, the terminal no longer needs to receive information from the source cell. Therefore, deactivating the source cell's protocol stack after cell handover can reduce the terminal's resource overhead.

[0090] In an optional implementation of the sixth aspect, the method further includes: deactivating the protocol stack of the source cell in a second time period and / or a second geographical region.

[0091] The second time period is, for example, the period after cell handover is completed, and the second geographical area is, for example, the area after cell handover is completed (or an area outside the coverage of the source cell, or an area where the channel quality of the source cell does not meet the transmission requirements). Activating the protocol stack of the source cell in the second time period and / or the second geographical area enables activation of the protocol stack based on cell handover requirements, thereby avoiding the resource waste caused by the terminal maintaining multiple protocol stacks.

[0092] In a seventh aspect, embodiments of this application provide a communication device. The communication device may include a processing unit and a communication unit, configured to perform: any method of the first aspect and its optional embodiments, or any method of the second aspect and its optional embodiments, or any method of the third aspect and its optional embodiments, or any method of the fourth aspect and its optional embodiments, or any method of the fifth aspect and its optional embodiments, or any method of the sixth aspect and its optional embodiments.

[0093] Eighthly, embodiments of this application provide a communication device, which may be a terminal or a chip applied to a terminal, or a network device or a chip applied to a network device. The communication device may include a processor. When the communication device is a terminal or a chip applied to a terminal, the processor is configured to execute: any method of the second aspect and its optional embodiments, or any method of the sixth aspect and its optional embodiments; when the communication device is a network device or a chip applied to a network device, the processor is configured to execute: any method of the first aspect and its optional embodiments, or any method of the third aspect and its optional embodiments, or any method of the fourth aspect and its optional embodiments, or any method of the fifth aspect and its optional embodiments.

[0094] Optionally, the communication device may also include a transceiver. When the communication device is a terminal or network device, the transceiver may be a transceiver circuit or an antenna, etc.; when the communication device is a chip used in a terminal or network device, the transceiver may be an input / output interface, pins, or circuits, etc.

[0095] Optionally, the communication device may further include a memory for storing computer programs or instructions. The processor executes the computer programs or instructions stored in the memory to cause the communication device to perform: any of the methods in the first aspect and its optional embodiments, or any of the methods in the second aspect and its optional embodiments, or any of the methods in the third aspect and its optional embodiments, or any of the methods in the fourth aspect and its optional embodiments, or any of the methods in the fifth aspect and its optional embodiments, or any of the methods in the sixth aspect and its optional embodiments. When the communication device is a terminal or network device, the memory may be a read-only memory or a random access memory, etc.; when the communication device is a chip applied to a terminal or network device, the memory may be a register or a cache, etc.

[0096] Ninthly, embodiments of this application provide a communication system, which includes one or more of the following communication devices:

[0097] A communication device for performing any method of the first aspect and its optional embodiments; a communication device for performing any method of the second aspect and its optional embodiments; a communication device for performing any method of the third aspect and its optional embodiments; and a communication device for performing any method of the fourth aspect and its optional embodiments.

[0098] In a tenth aspect, embodiments of this application provide a communication system comprising: a communication device for performing any method of the fifth aspect and its optional embodiments; and / or, a communication device for performing any method of the sixth aspect and its optional embodiments.

[0099] Eleventhly, embodiments of this application provide a computer-readable storage medium storing a computer program or instructions; when the computer program or instructions are executed on a communication device, the communication device performs: any method of the first aspect and its optional embodiments, or any method of the second aspect and its optional embodiments, or any method of the third aspect and its optional embodiments, or any method of the fourth aspect and its optional embodiments, or any method of the fifth aspect and its optional embodiments, or any method of the sixth aspect and its optional embodiments.

[0100] In a twelfth aspect, embodiments of this application provide a computer program product comprising: a computer program or instructions; when the computer program or instructions are executed by a communication device, the communication device performs: any one of the methods in the first aspect and its optional embodiments, or any one of the methods in the second aspect and its optional embodiments, or any one of the methods in the third aspect and its optional embodiments, or any one of the methods in the fourth aspect and its optional embodiments, or any one of the methods in the fifth aspect and its optional embodiments, or any one of the methods in the sixth aspect and its optional embodiments. Attached Figure Description

[0101] Figure 1 This is a schematic diagram of the architecture of the communication system used in the embodiments of this application;

[0102] Figure 2 This is a schematic diagram of an open wireless access network architecture provided in an embodiment of this application;

[0103] Figure 3 This is a schematic diagram of an NTN architecture including a transparent transmission mode satellite provided in an embodiment of this application;

[0104] Figure 4 This is a schematic diagram of an NTN architecture including regenerable mode satellites provided in an embodiment of this application;

[0105] Figure 5 This is a schematic diagram of a cell handover provided in an embodiment of this application;

[0106] Figure 6 This is a schematic diagram of a communication method provided in an embodiment of this application;

[0107] Figure 7 This is a schematic diagram of a region-specific random access resource provided in an embodiment of this application;

[0108] Figure 8 This is a schematic diagram of another communication method provided in an embodiment of this application;

[0109] Figure 9 This is a schematic diagram of another communication method provided in an embodiment of this application;

[0110] Figure 10 This is a schematic diagram of a cell handover method based on a dual-activation protocol stack provided in an embodiment of this application;

[0111] Figure 11 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0112] Figure 12This is a schematic diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0113] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0114] Figure 1 This is a schematic diagram of the architecture of the communication system 1000 used in the embodiments of this application. Figure 1 As shown, the communication system includes a radio access network (RAN) 100, wherein the RAN 100 includes at least one RAN node (e.g., Figure 1 The 110a-110b in the model (collectively referred to as 110) may also include at least one terminal (such as...). Figure 1 RAN100, denoted as RAN100, comprises RAN nodes 120a-120j, collectively referred to as RAN120. RAN100 may also include other RAN nodes, such as wireless relay equipment and / or wireless backhaul equipment. Figure 1 (Not shown in the image). Terminal 120 is wirelessly connected to RAN node 110. Terminals and RAN nodes can be interconnected via wired or wireless means. Communication system 1000 may also include a core network (CN) 200. RAN node 110 is connected to core network 200 via wireless or wired means. The core network equipment in core network 200 and RAN node 110 in RAN 100 can be independent physical devices, or they can be the same physical device integrating the logical functions of core network equipment and RAN node. Communication system 1000 may also include Internet 300.

[0115] RAN100 can be an evolved universal terrestrial radio access (E-UTRA) system, a new radio (NR) system, or a future radio access system as defined in the 3rd generation partnership project (3GPP). RAN100 can also include two or more of the above-mentioned different radio access systems. RAN100 can also be an open RAN (O-RAN). RAN100 can also be an NTN, or a converged NTN and TN network.

[0116] RAN nodes, also known as network devices, access network devices, radio access network devices, RAN entities, or access nodes, are used to help terminals access communication systems wirelessly. Optionally, RAN nodes can also be simply referred to as RAN.

[0117] In one application scenario, a RAN node can be a base station (BS), an evolved NodeB (eNodeB), a transmission reception point (TRP), a next-generation NodeB (gNB) in a 5G mobile communication system, a base station in a future mobile communication system, an access point (AP) in a long-range radio (LoRa) system, or an AP in a vehicle-to-everything (V2X) system. A RAN node can also be a macro base station (such as...). Figure 1 110a in the text), can also be a micro base station or an indoor station (such as... Figure 1 110b in the middle can also be a relay node or a donor node.

[0118] In another application scenario, multiple RAN nodes can collaborate to help terminals achieve wireless access, with different RAN nodes implementing different functions of the base station. For example, a RAN node can be a central unit (CU), a distributed unit (DU), or a radio unit (RU). The CU performs the functions of the base station's radio resource control (RRC) protocol and packet data convergence protocol (PDCP), and can also perform the functions of the service data adaptation protocol (SDAP). The DU performs the functions of the base station's radio link control (RLC) layer and medium access control (MAC) layer, and can also perform some or all of the physical (PHY) layer functions. For specific descriptions of these protocol layers, refer to the relevant 3GPP technical specifications. The RU can be used to implement radio frequency signal transmission and reception. The CU and DU can be set up as two independent RAN nodes, or integrated into the same RAN node, for example, integrated into the baseband unit (BBU). RUs can be included in radio frequency equipment, such as remote radio units (RRUs), active antenna units (AAUs), or remote radio heads (RRHs). CUs can be further divided into two types of RAN nodes: central unit control plane (CU-CP) and central unit user plane (CU-UP).

[0119] In different systems, RAN nodes may have different names. For example, in an O-RAN system, a CU can be called an open CU (O-CU), a DU can be called an open DU (O-DU), and a RU can be called an open RU (O-RU).

[0120] Figure 2 This is a schematic diagram of an O-RAN architecture provided by an embodiment of this application.

[0121] like Figure 2As shown, O-RAN includes O-CU, O-DU, and O-RU. Optionally, O-CU and O-DU can be integrated into BBU. BBU and O-RU can be co-located or non-co-located. O-CU can communicate with the core network via backhaul link, O-CU and O-DU can communicate via midhaul link, O-DU and O-RU can communicate via fronthaul link, and O-RU and terminal can communicate via air interface.

[0122] The RAN node in this application embodiment can be implemented through software modules, hardware modules, or a combination of software and hardware modules. For example, the RAN node can be a server loaded with the corresponding software module. This application embodiment does not limit the specific technology or equipment form used in the RAN node. For ease of description, a base station is used as an example of a RAN node in the following description.

[0123] A terminal is a device with wireless transceiver capabilities, capable of sending signals to or receiving signals from a base station. Terminals can also be called terminal equipment, user equipment (UE), mobile station, or mobile terminal, etc. Terminals can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), the Internet of Things (IoT), virtual reality (VR), augmented reality (AR), industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, and smart cities. A terminal can be a mobile phone (e.g.,...). Figure 1 120a, 120e, 120f and 120j), laptops (such as Figure 1 120g), printers with wireless transceiver capabilities (such as...) Figure 1 120h), wearable devices, vehicles (such as Figure 1 120b in the middle), charging piles (such as Figure 1 120c in the middle), aircraft (such as Figure 1The terminal can be a satellite communication module, satellite phone, or a component thereof, such as a very small aperture terminal (VSAT), a portable station, a fixed station, a vehicle-mounted or airborne satellite communication terminal, etc. It should be understood that a satellite communication terminal can serve as a micro base station to further provide data interfaces to accessed user equipment. The embodiments of this application do not limit the specific technology or device form used in the terminal.

[0124] All the terminals described above, if located in a vehicle (e.g., placed inside the vehicle or installed outside the vehicle), can be considered vehicle terminals. Vehicle terminals can also be called vehicle modules, vehicle chips, or on-board units (OBU).

[0125] Base stations and terminals can be fixed or mobile. They can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on water; and they can be deployed on aircraft, balloons, or artificial satellites. This application does not limit the application scenarios for base stations and terminals.

[0126] The roles of base stations and terminals can be relative, for example, Figure 1 The 120i (which could be a drone) can be configured as a mobile base station. For those 120j accessing the wireless access network 100 via the 120i, the 120i is a base station; however, for the 110a, the 120i is a terminal, meaning that the 110a and 120i communicate via a wireless air interface protocol. Of course, the 110a and 120i can also communicate via a base station-to-base station interface protocol; in this case, the 120i is also a base station relative to the 110a. Therefore, both base stations and terminals can be collectively referred to as communication devices. Figure 1 The 110a and 110b in the text can be referred to as communication devices with base station functions. Figure 1 The 120a-120j in the text can be referred to as communication devices with terminal functions.

[0127] In the embodiments of this application, the functions of the base station can also be performed by modules (such as chips or modems) within the base station, or by a control subsystem that includes base station functions. This control subsystem, including base station functions, can be a control center in the application scenarios described above, such as smart grids, industrial control, intelligent transportation, or smart cities. Similarly, the functions of the terminal can be performed by modules (such as chips or modems) within the terminal, or by a device that includes terminal functions.

[0128] To facilitate understanding of the embodiments of this application, the technologies involved in the embodiments of this application will be briefly introduced below.

[0129] 1. NTN.

[0130] Networks that utilize non-terrestrial network equipment for communication can be called NTNs. NTNs can include aerial network equipment such as satellites, unmanned aircraft systems (UAS), or high-altitude platform stations (HAPS). They offer advantages such as wide coverage, long communication distance, high reliability, high flexibility, and high throughput, and are unaffected by geographical environment, climate conditions, or natural disasters, and have been widely used in various fields. For example, NTNs can provide communication services to areas that are difficult for terrestrial networks to cover (such as oceans, forests, deserts, or remote areas); on the other hand, NTNs can enhance the reliability of mobile communications, such as providing more stable communication services for users in high-speed moving scenarios like trains and airplanes; in addition, NTNs can provide more data transmission resources and support the connection of a larger number of terminal devices. The following explanation uses an NTN that includes satellites as an example.

[0131] Generally speaking, the higher a satellite's orbit, the larger its coverage area, but the longer the communication latency. Based on orbital altitude, satellites can be divided into geostationary earth orbit (GEO) satellites, medium earth orbit (MEO) satellites, and low earth orbit (LEO) satellites.

[0132] GEO satellites orbit at an altitude of approximately 35,000 km. GEO satellites are relatively stationary relative to the ground and can provide a large coverage area. However, the excessive distance between GEO satellites and the ground necessitates large-diameter antennas for communication. This large distance also results in significant transmission delays, making it impossible to meet the demands of real-time services. Furthermore, the scarcity of geostationary orbit resources, high launch costs, and the inability to cover the polar regions are all factors that constrain the development of GEO satellites.

[0133] MEO satellites orbit at altitudes ranging from approximately 2,000 km to 35,000 km. Their orbital altitude is lower than that of GEO satellites but higher than that of LEO satellites, allowing for global coverage with a relatively small number of MEO satellites. Currently, MEO satellites are primarily used for positioning and navigation.

[0134] LEO satellites orbit at altitudes ranging from approximately 300 km to 2000 km. Their relatively low orbital altitude results in lower transmission latency and launch costs compared to GEO and MEO satellites. Consequently, communication systems based on LEO satellites have experienced significant development in recent years.

[0135] Based on their operating modes, satellites can generally be divided into two main categories: transparent mode and regenerative mode.

[0136] 1.1 Transparent transmission mode.

[0137] Figure 3 This is a schematic diagram of the NTN architecture including satellites in transparent transmission mode. In transparent transmission mode, the satellite's main role is as a layer (L1) relay, performing tasks such as wireless frequency filtering, frequency conversion, and amplification of physical layer signals; it does not have higher protocol layer functions. The terminal connects to terrestrial network equipment via the satellite, and this terrestrial network equipment includes... Figure 3 The diagram shows a gateway and a base station, where the gateway can also be referred to as a ground station, earth station, signaling station, or gateway station. In transparent transmission mode, the satellite and gateway can be considered as RRUs, and the satellite, gateway, and base station together implement the RAN functions. Optionally, the gateway can also be integrated with the base station.

[0138] For example, in the uplink, the terminal sends an uplink signal (carrying the terminal's uplink data) through the Uu interface. After receiving the uplink signal, the satellite forwards it to the gateway (the satellite may perform frequency conversion on the signal). The gateway then forwards the uplink signal to the base station. Upon receiving the uplink signal, the base station processes it to obtain the data the terminal needs to send to the core network. It can then send the data to the core network through the interface between the base station and the core network (e.g., the NG interface). The core network can then send the data to the internet through the N6 interface. In the downlink, the internet sends downlink data to the core network through the N6 interface. The core network then sends the downlink data to the base station through the interface between the base station and the core network. Upon receiving the downlink data, the base station processes it to generate a downlink signal (carrying downlink data). This downlink signal can then be sent to the gateway through the Uu interface. The gateway sends the downlink signal to the satellite, which forwards it to the terminal (the satellite may perform frequency conversion on the signal).

[0139] It should be noted that the names of the interfaces in various descriptions in this application are examples rather than limitations. As technology develops, other interfaces with the same or similar functions may appear, and these new interfaces are also applicable to this application. This application does not limit the interfaces for data transmission between devices.

[0140] 1.2 Regeneration Mode.

[0141] In regeneration mode, the satellite possesses some or all of the functions of a base station; for example, it can process signals received from the ground at the physical layer, MAC layer, and RLC layer. The gateway can forward signaling and data between the satellite and the core network.

[0142] Figure 4 This is a schematic diagram of an NTN architecture that includes regenerative mode satellites. In this architecture, the satellites have full base station functions and can be considered as base stations. The satellites and gateways together implement the RAN functions. Terminals communicate with the satellites via the Uu interface, and the satellites communicate with the core network via the NG interface. The NG interface between the satellites and gateways is carried on the satellite radio interface (SRI). The core network communicates with the Internet via the N6 interface.

[0143] In regeneration mode, since satellites have base station functions, they can also communicate with each other via inter-satellite links.

[0144] The above division of NTN architecture is illustrative and not limiting; the NTN architecture applicable to this application is not limited to this. For example, each satellite can provide services to multiple terminals, each satellite can communicate with multiple gateways, and each gateway can also communicate with multiple satellites. Furthermore, DU functionality can be deployed on satellites, and CU functionality can be deployed on terrestrial network equipment.

[0145] 2. Cell handover.

[0146] A cell can be viewed as a wireless signal coverage area that is identified by PCI or CGI. Different cells can also be distinguished by a serving cell index. The embodiments of this application do not limit the method of identifying cells.

[0147] Due to the movement of the terminal or changes in the channel state, the cell to which the terminal is connected will change. That is, the terminal can switch from one cell to another. The cell before the switch can be called the source cell, and the cell after the switch can be called the target cell.

[0148] Figure 5This is a schematic diagram of a cell handover provided by an embodiment of this application. The satellite connects to the core network through a gateway and communicates with the TN base station through the core network. The signal coverage area of ​​the satellite can be referred to as an NTN cell, and the signal coverage area of ​​the TN base station can be referred to as a TN cell. Solid arrows indicate communication connections, and dashed arrows indicate the direction of movement.

[0149] Currently, the terminal maintains a connection with the NTN cell but not with the TN cell. As the satellite and terminal move, the channel condition between the terminal and the satellite deteriorates, requiring the terminal to find a cell with better channel condition. Through measurement, the terminal determines that the channel condition of the TN cell meets the requirements, and then the terminal can establish a connection with the TN cell and disconnect from the NTN cell. This process can be called a handover from the NTN cell to the TN cell, where the NTN cell can be called the source cell and the TN cell can be called the target cell.

[0150] Similarly, if a terminal switches from a TN cell to an NTN cell, the TN cell can be called the source cell, and the NTN cell can be called the target cell.

[0151] The above description of cells is illustrative and not limiting. As technology advances, concepts with the same or similar functions as cells may emerge, and these concepts also apply to the embodiments of this application. Furthermore, cell handover can be triggered by a base station, a terminal, or a third-party device other than a base station or terminal.

[0152] During cell handover, the source cell needs to send handover information (e.g., ephemeris information for NTN cells) to the terminal. The source cell can obtain this handover information from the target cell. For handovers between TN cells, since TN cells typically have low-latency interfaces (e.g., Xn or F1 interfaces), obtaining handover information from the target cell does not cause significant mobility interruption. However, for handovers between NTN and TN cells, continuing to use this method will result in substantial mobility interruption.

[0153] like Figure 5 As shown, communication between satellites and TN base stations requires traversing one (or even multiple) core networks, and the information used for cell handover takes a considerable amount of time to travel from the target cell to the source cell. Even if direct communication between satellites and TN base stations were possible, the long distance between them, coupled with path loss and retransmissions, still results in a significant delay in the handover process, leading to excessive mobile interruption time.

[0154] The communication method provided in the embodiments of this application is described below. For example... Figure 6 As shown, method 600 is executed by the source cell and the terminal respectively, or method 600 is executed by chips applied to the source cell and the terminal respectively. The source cell can be implemented by a node (e.g., gNB, TRP, or DU) with full or partial base station functionality. The following description uses the execution of method 600 by the source cell and the terminal as an example. Method 600 includes the following:

[0155] S610, the terminal sends type information to the source cell, the type information being used to indicate whether the target cell is a TN cell or an NTN cell.

[0156] Accordingly, the source cell performs the following: receiving type information from the terminal and determining whether the target cell is a TN cell or an NTN cell based on the type information.

[0157] Optionally, the type information can be a bit in a measurement report, where the measurement report carries the identifier (ID) of the target cell. For example, a bit of "0" indicates that the target cell is a TN cell, and a bit of "1" indicates that the target cell is an NTN cell. The measurement report can be a message carrying measured or predicted values ​​of the target cell's channel quality, a message carrying measured or predicted values ​​of the terminal's location, or other messages. This application does not limit the specific form of the type information or the message carrying the type information.

[0158] It should be noted that S610 is an optional step for the source cell. The source cell can execute S620 based on type information or not.

[0159] S620, if the target cell meets the first condition, the source cell determines the first information, wherein the first information is information configured by the core network for cell handover, or the first information is pre-configured information for cell handover; wherein the target cell meets the first condition, including at least one of the following: the communication delay between the target cell and the source cell is greater than or equal to a first threshold, the cell bandwidth of the target cell is less than or equal to a second threshold, the transmission path length between the target cell and the source cell is greater than or equal to a third threshold, or the communication interface between the target cell and the source cell has expired or does not exist.

[0160] The source cell can determine whether the terminal meets the cell handover conditions based on the measurement report. After determining that the terminal meets the cell handover conditions, it determines whether the target cell meets the first condition. If the target cell meets the first condition, it can be called a weakly cooperative cell. It should be noted that a weakly cooperative cell is used to characterize that the communication latency between the target cell and the source cell does not meet the cell handover requirements. A weakly cooperative cell can also be replaced by a non-real-time cooperative cell or other names that express a similar meaning.

[0161] The first information is used for cell handover, and it can contain different content depending on the scenario.

[0162] For example, when the target cell is a TN cell, and when the TN cell has corresponding area-dedicated access resources, the first information may include resource information, which is used to configure or activate the area-dedicated random access resources corresponding to the target cell.

[0163] For example, when the target cell is an NTN cell, the first information may include the ephemeris information of the NTN cell to assist the terminal in accessing the NTN cell.

[0164] The following section first introduces an implementation method for determining whether a target cell is a weakly cooperative cell, and then introduces an implementation method for the first information.

[0165] Optionally, the source cell can determine whether the target cell is a weakly cooperative cell based on one or more of the following parameters: inter-cell communication latency, cell bandwidth, and transmission path.

[0166] For example, a source cell can query locally stored latency information based on the target cell's ID. This latency information indicates the communication latency between the source and target cells. If the communication latency is greater than or equal to a first threshold, the source cell can determine that the target cell is a weakly cooperating cell; if the communication latency is less than the first threshold, the source cell can determine that the target cell is a non-weakly cooperating cell. The first threshold can be configured by the core network, or it can be predefined or preconfigured by a standard; the latency information can be preconfigured or determined based on the data transmission latency between the source and target cells.

[0167] For example, a source cell can query locally stored bandwidth information based on the target cell's ID. This bandwidth information indicates the communication bandwidth between the source and target cells. If the communication bandwidth is less than or equal to a second threshold, the source cell can determine that the target cell is a weakly cooperating cell; if the communication bandwidth is greater than the second threshold, the source cell can determine that the target cell is a non-weakly cooperating cell. The second threshold can be configured by the core network, or it can be predefined or pre-configured by a standard; the bandwidth information can be pre-configured or determined based on the data transmission rate between the source and target cells.

[0168] For example, a source cell can query locally stored path information based on the target cell's ID. This path information indicates the length of the transmission path between the source and target cells. If the length of the transmission path is greater than or equal to a third threshold, the source cell can determine that the target cell is a weakly cooperating cell; if the length of the transmission path is less than the third threshold, the source cell can determine that the target cell is a non-weakly cooperating cell. The third threshold can be configured by the core network, or it can be predefined or pre-configured by a standard; the path information can be pre-configured or determined based on the signal transmission distance between the source and target cells.

[0169] The above example illustrates how a source cell determines whether a target cell is a weakly cooperating cell based on a single piece of information. When a source cell determines whether a target cell is a weakly cooperating cell based on multiple pieces of information, it can do so according to various criteria, such as the result indicated by the majority of the multiple pieces of information. This application does not limit this approach.

[0170] For example, when two or three of the time delay information, bandwidth information, and transmission path information indicate that the target cell is a weakly cooperating cell, the source cell can determine that the target cell is a weakly cooperating cell; when two or three of the time delay information, bandwidth information, and transmission path information indicate that the target cell is a non-weakly cooperating cell, the source cell can determine that the target cell is a non-weakly cooperating cell.

[0171] Furthermore, the determination of weakly cooperating cells based on latency information, bandwidth information, and path information is an example rather than a limitation, and other information that can determine whether a target cell is a weakly cooperating cell is also applicable to this application.

[0172] Optionally, the source cell can determine whether the target cell is a weakly cooperative cell based on the state of the interface between the target cell and the source cell.

[0173] Taking the Xn interface as an example, if the configuration parameters of the Xn interface (such as routing information) have an expiration date, or if the heartbeat detection of the Stream Control Transmission Protocol (SCTP) used by the Xn interface fails, or if the source cell or target cell actively releases the Xn interface resources due to load or fault, the Xn interface may expire or become non-existent. In this case, the source cell and the target cell need to work together through the core network, and the source cell can determine that the target cell is a weakly cooperating cell.

[0174] Optionally, the source cell may determine whether the target cell is a weakly cooperative cell based on one or more of the following, if the interface exists and is valid: inter-cell communication latency, cell bandwidth, and transmission path.

[0175] Optionally, the source cell can record the status of neighboring cells (i.e., whether the neighboring cells are weakly cooperating cells) through a table. One possible table is shown in Table 1.

[0176] Table 1

[0177]

[0178]

[0179] In Table 1, the contents of the cell ID column can be PCI, CGI or other information used to identify the cell, and "0" in the cell status column indicates a weakly coordinated cell and "1" indicates a non-weakly coordinated cell.

[0180] The source cell can update Table 1 periodically or non-periodically. For example, after the source cell determines the status of neighboring cells, if Table 1 does not contain the IDs of neighboring cells, the source cell can add the IDs of neighboring cells to the Cell ID column and add the status of neighboring cells to the Cell Status column. If Table 1 contains the IDs of neighboring cells, the source cell can update the cell status of neighboring cells to the latest status.

[0181] After determining that the terminal needs to switch to the target cell, the source cell can look up the cell status of the target cell in Table 1 based on the target cell's ID (the target cell is usually a neighboring cell), thereby determining whether the target cell is a weakly cooperating cell.

[0182] Optionally, the source cell can also determine whether the target cell is a weakly cooperative cell based on the type information sent by the terminal.

[0183] For example, if the source cell is a TN cell and the type information indicates that the target cell is an NTN cell, then the source cell can determine that the target cell is a weakly cooperating cell, that is, the target cell meets the first condition; if the type information indicates that the target cell is a TN cell, then the source cell can determine that the target cell is a non-weakly cooperating cell, that is, the target cell does not meet the first condition.

[0184] For example, if the source cell is an NTN cell, and the type information indicates that the target cell is an NTN cell, then the source cell can determine that the target cell is a non-weakly cooperating cell, that is, the target cell does not meet the first condition; if the type information indicates that the target cell is a TN cell, then the source cell can determine that the target cell is a weakly cooperating cell, that is, the target cell meets the first condition.

[0185] Determining whether the target cell is a weakly cooperative cell based on type information eliminates the need for the source cell to maintain a cell status list (e.g., Table 1), thus reducing the resource overhead of the source cell.

[0186] After determining that the target cell is a weakly cooperative cell, the source cell can obtain the first information from the core network or obtain the pre-configured first information from the local network.

[0187] For example, the source cell can send a request message to the core network to request first information. The core network then sends the first information to the source cell based on this request message.

[0188] For example, after the source cell and the target cell become neighboring cells, the core network can proactively configure initial information for the source cell. After the source cell determines that the target cell is a weakly cooperative cell, it can obtain the initial information pre-configured by the core network locally.

[0189] It should be noted that the information obtained by the source cell from the core network may include, in addition to the first information (i.e., the information required by the terminal to perform cell handover), the information required by the source cell to perform cell handover.

[0190] After the source cell obtains the first information, it can perform the following steps.

[0191] S630, the source cell sends the first information to the terminal.

[0192] Accordingly, the terminal executes: receive the first information from the source cell.

[0193] Taking L1 / L2 triggered mobility (LTM) handover as an example, the first piece of information can be the information required for the terminal to perform LTM handover.

[0194] Optionally, the first information includes resource information. The resource information is used to configure or activate the area-specific random access resources corresponding to the target cell, such as an area-specific preamble.

[0195] Optionally, the area-specific random access resources corresponding to the target cell may have one or more of the following characteristics:

[0196] The area-dedicated random access resource corresponding to the target cell is related to the transmission method of the target cell's TA. Wherein, if the target cell meets the first condition, the area-dedicated random access resource is used to instruct the TA to be transmitted directly from the target cell to the terminal; if the target cell does not meet the first condition, the area-dedicated random access resource is used to instruct the TA to be transmitted to the terminal through the source cell.

[0197] The area-specific random access resources corresponding to the target cell are valid when the terminal is located in the target area, where the target area includes the overlapping area between the target cell and the source cell.

[0198] Figure 7 This is a schematic diagram of a region-specific random access resource provided in an embodiment of this application.

[0199] Multiple ground base stations exist within the satellite's signal coverage area, namely gNB1, gNB2, and gNB3. gNB2 and gNB3 are relatively close, while gNB1 is farther from the other two gNBs. Therefore, the signal coverage area of ​​gNB1 can be divided into one region (referred to as Region 1), and the signal coverage areas of gNB2 and gNB3 can be divided into another region (referred to as Region 2). Region 1 is configured with preamble 1, and Region 2 is configured with preamble 2. When a terminal is located in Region 1, it can use preamble 1 to perform random access with gNB1; when the terminal is located in Region 2, it can use preamble 2 to perform random access with either gNB2 or gNB3. In this case, preamble 1 can be referred to as the region-specific random access resource for gNB1, and preamble 2 can be referred to as the region-specific random access resource for gNB2 and gNB3.

[0200] The terminal can determine whether the area-specific random access resource is effective based on the reference location and distance threshold associated with the area-specific random access resource.

[0201] For example, in region 1, the location of gNB1 can be used as a reference location. If the distance between the terminal and the reference location is greater than a first distance threshold, the terminal determines that the region-specific random access resource of gNB1 is not effective and does not use preamble 1 to perform random access with gNB1. If the distance between the terminal and the reference location is less than or equal to the first distance threshold, the terminal determines that the region-specific random access resource of gNB1 is effective and uses preamble 1 to perform random access with gNB1.

[0202] For example, in region 2, the midpoint of the line connecting gNB2 and gNB3 can be used as a reference position. If the distance between the terminal and the reference position is greater than the second distance threshold, the terminal determines that the region-specific random access resources of gNB2 and gNB3 are not effective and does not use preamble 2 to perform random access with gNB2 or gNB3. If the distance between the terminal and the reference position is less than or equal to the second distance threshold, the terminal determines that the region-specific random access resources of gNB2 and gNB3 are effective and uses preamble 2 to perform random access with gNB2 or gNB3.

[0203] Therefore, configuring the area-specific random access resource is effective when the terminal is located in the target area. This can prevent the terminal from occupying the area-specific random access resource for a long time and improve the utilization rate of the area-specific random access resource.

[0204] It should be noted that, in addition to the preamble, area-specific random access resources may also include other resources used for random access.

[0205] The area-specific random access resources (ADRs) corresponding to the target cell can be associated with the transmission method of the target cell's TA (Transmission Type). TAs are typically carried within the RAR (Real-Agent Record); therefore, the "TA transmission method" can also be referred to as the "RAR transmission method." In other words, the area-specific random access resources (ADRs) corresponding to the target cell can be associated with the transmission method of the target cell's RAR.

[0206] For example, the area-specific random access resources corresponding to Area 1 include preamble 1-1 and preamble 1-2. Preamble 1-1 indicates that the TA (Transmission Ability) is sent directly from the target cell to the terminal, while preamble 1-2 indicates that the TA is sent through the source cell to the terminal. If the target cell meets the first condition, the source cell can configure preamble 1-1 for the terminal using the resource information in the first information. The terminal sends preamble 1-1 to the target cell based on the configuration in the resource information and receives the TA from the target cell (the TA is determined by the target cell based on preamble 1-1). If the target cell does not meet the first condition, the source cell can configure preamble 1-2 for the terminal using the resource information in the first information. The terminal sends preamble 1-2 to the target cell based on the configuration in the resource information and receives the TA from the source cell (the TA is determined by the target cell based on preamble 1-2).

[0207] When the target cell meets the first condition, the latency between the target cell and the source cell is relatively large. Sending the TA directly from the target cell to the terminal can reduce the TA transmission latency. When the target cell does not meet the first condition, the latency between the target cell and the source cell is relatively small. Sending the TA from the source cell to the terminal reuses the existing TA transmission method. This not only meets the mobility interruption time requirements of cell handover but also improves the forward compatibility of the embodiments of this application and can also increase the communication rate during cell handover.

[0208] It should be noted that within the target area (e.g., area 1 and area 2), the terminal can also use non-area dedicated random access resources for random access.

[0209] Optionally, the first information includes time information. The time information is used to configure or activate the first time period, which is located before the time when the cell handover command is sent, and is used for the terminal to perform uplink and downlink synchronization with the target cell.

[0210] In LTM handover, the first time period can also be called the LTM interval (LTM-GAP), where the LTM interval can be a UE-specific interval. For example, when the transmission delay from the terminal to the target cell is large, a longer LTM interval can be configured for the terminal; when the transmission delay from the terminal to the target cell is small, a shorter LTM interval can be configured for the terminal.

[0211] The source cell can configure the first time period through one or more parameters of length, period, and offset.

[0212] For example, when the terminal has been configured with the starting time domain position of the first time period, the time information may only include the length of the first time period, and the terminal can determine the time domain position of the first time period based on the starting time domain position and the length of the first time period; when the terminal has been configured with the length of the first time period, the time information may only include the period and offset of the first time period, where the time reference point of the offset may be a frame boundary or other predefined time reference point; when the terminal has not been configured with parameters related to the first time period, the time information may include the length, period, and offset of the first time period.

[0213] The terminal determines a first time period based on the time information contained in the first information, and completes uplink and downlink synchronization with the target cell within the first time period. The source cell cannot schedule the terminal during the first time period. Because the first information is sent to the terminal before the cell handover command, the terminal can complete uplink and downlink synchronization before the cell handover, thereby reducing the mobility interruption time during cell handover.

[0214] Alternatively, the aforementioned time information can be determined by the source cell and no longer obtained from the target cell.

[0215] The resource information and time information described above are examples of the content included in the first information. The first information can also include other content.

[0216] For example, the first information may also include information about non-cell-specific random access resources. When the terminal fails to access the target cell using cell-specific random access resources, it can also use non-cell-specific random access resources for random access.

[0217] Optionally, the source cell can send the first information to the terminal via an RRC reconfiguration message. After receiving the RRC reconfiguration message, the terminal sends an RRC reconfiguration complete message to the source cell, indicating that the first information has been received. Subsequently, the terminal can perform the following steps.

[0218] S640, the terminal performs cell handover based on the first information.

[0219] The first information can be configured (or indicated; or activated) for different cell handover types, and the terminal performs the corresponding operation according to the cell handover type corresponding to the first information.

[0220] For example, if the first information is configured for LTM handover, the terminal will subsequently perform LTM handover-related operations. If the first information is configured for Layer 3 (L3) handover, the terminal will subsequently perform L3 handover-related operations. The first information can also be configured for dual active protocol stack (DAPS) handover, as described below, and the terminal will perform DAPS handover-related operations according to the configuration of the first information.

[0221] Optionally, if the first information includes resource information, and the resource information is configured with area-specific random access resources corresponding to the target cell, then the terminal can use the area-specific random access resources (e.g., area-specific preamble) to access the target cell.

[0222] Optionally, if the first information includes time information, the terminal can perform uplink and downlink synchronization with the target cell within the first time period configured by the time information.

[0223] For details on how the terminal performs cell handover based on resource information and / or time information, please refer to the embodiments related to "resource information" and "time information" above.

[0224] The above describes an example of a source cell obtaining first information when the target cell meets the first condition. Optionally, if the target cell does not meet the first condition, it indicates that the latency between the target cell and the source cell is small. The source cell can reuse the existing cell handover method to send a handover request to the target cell in order to obtain the first information from the target cell.

[0225] In summary, the source cell or core network stores the first information. During cell handover, the source cell first determines whether the target cell meets the first condition. If the target cell meets the first condition, the source cell obtains the first information from the core network or locally, and no longer obtains the first information from the target cell, thereby reducing the mobility interruption time of the terminal when handover between different types of cells.

[0226] The following example uses LTM handover to illustrate the process of a terminal performing cell handover based on the first piece of information. In this example, the first piece of information corresponds to the LTM candidate cell configuration information. Figure 8 As shown, Method 800 can be divided into four stages: LTM switchover preparation stage, advance synchronization stage, LTM switchover execution stage, and LTM switchover completion stage. These stages are described below.

[0227] The main purpose of the LTM handover preparation phase is to prepare for subsequent phases, such as identifying candidate cells and configuring the terminal with the information required for LTM handover. The LTM handover preparation phase can include four steps: S801 to S804.

[0228] S801, the terminal sends a measurement report to the source cell.

[0229] The measurement reports here may include signal quality measurement reports and / or location measurement reports. The signal measurement reports may include measured or predicted values ​​of parameters related to the signal quality of the candidate cells, such as reference signal received power (RSRP), reference signal received quality (RSRQ), or signal to interference plus noise ratio (SINR). The location measurement reports may include measured or predicted values ​​of parameters related to the terminal's location, such as the terminal's location determined based on the global navigation satellite system (GNSS), positioning reference signal (PRS), or sounding reference signal (SRS).

[0230] The terminal can periodically send measurement reports based on the configuration of the source cell, or it can send measurement reports based on signal quality trigger events. This application embodiment does not limit the method by which the terminal sends measurement reports to the source cell or the specific content of the measurement reports. Furthermore, candidate cells are usually neighboring cells of the source cell and can be pre-configured by the source cell or the core network.

[0231] Optionally, the measurement report may carry type information, which indicates the type of the candidate cell, such as indicating whether the candidate cell is a TN cell or an NTN cell.

[0232] It should be noted that the type information is optional for the source cell. The source cell can perform cell handover based on the type information or not.

[0233] S802, the source cell performs LTM candidate preparation.

[0234] If the terminal meets the cell handover conditions (e.g., the signal quality of the source cell does not meet the requirements), the source cell can perform LTM candidate preparation based on the measurement report.

[0235] For example, the source cell can determine a candidate cell from multiple candidate cells as the target cell based on the measurement report, and determine whether the target cell is a weakly cooperative cell (i.e., determine whether the target cell meets the first condition). For specific determination methods, please refer to the relevant description in S620.

[0236] If the source cell determines that the target cell is a non-weakly cooperating cell, it means that the latency between the source and target cells is relatively small. In this case, the source cell can directly send a handover request to the target cell, for example, through the Xn or F1 interface. After receiving the handover request, the target cell can send the LTM candidate cell configuration information to the source cell so that the source cell can configure the terminal to perform LTM handover.

[0237] If the source cell determines that the target cell is a weakly cooperating cell, it means that the time delay between the source cell and the target cell is large. In this case, the source cell can execute one of the following options:

[0238] Option 1: The source cell sends a request message to the core network, which is used to obtain LTM candidate cell configuration information;

[0239] Option 2: The source cell selects LTM candidate cell configuration information from locally stored pre-configuration information, where the pre-configuration information can be pre-configured by the core network.

[0240] The LTM candidate cell configuration information here is an example of the first information mentioned above, and may include resource information and / or time information. For details, please refer to the description of the first information above.

[0241] S803, the source cell sends an RRC reconfiguration message to the terminal. The RRC reconfiguration message carries LTM candidate cell configuration information.

[0242] S804, the terminal sends an RRC reconfiguration complete message to the source cell.

[0243] If the LTM candidate cell configuration information includes time information, the terminal can perform advance synchronization within the LTM-GAP configured for the time information. Advance synchronization refers to the terminal synchronizing before receiving the cell handover command.

[0244] S805, the terminal performs uplink and downlink synchronization with the candidate cell (i.e., the target cell).

[0245] Optionally, if the LTM candidate cell configuration information does not indicate the transmission method of the target cell's TA (e.g., the area-dedicated random access resource configured in the LTM candidate cell configuration information is not associated with the transmission method of the TA), the source cell can indicate the transmission method of the target cell's TA before the terminal executes S805.

[0246] For example, the source cell can add a bit (an example of the second information) to the downlink control information (DCI). When the state of this bit is "0", it instructs the terminal to obtain the TA from the RAR of the target cell; when the state of this bit is "1", it instructs the terminal to obtain the TA from the MAC control element (CE) of the source cell.

[0247] When the target cell is a weakly cooperative cell, the latency between the target cell and the source cell is relatively large. Sending the TA directly from the target cell to the terminal can reduce the TA transmission latency. When the target cell is not a weakly cooperative cell, the latency between the target cell and the source cell is relatively small. Sending the TA from the source cell to the terminal reuses the existing TA transmission method, which can improve the forward compatibility of this embodiment and also improve the communication rate during cell handover. Therefore, by indicating the TA transmission method through the second information, different scenarios can be flexibly adapted.

[0248] During uplink and downlink synchronization, if the LTM candidate cell configuration information is configured with area-dedicated random access resources and these area-dedicated random access resources are in effect, the terminal and the target cell can use the area-dedicated random access resources for synchronization. If the LTM candidate cell configuration information is not configured with area-dedicated random access resources, or if the area-dedicated random access resources configured in the LTM candidate cell configuration information are not in effect, the terminal and the target cell can use non-area-dedicated random access resources for synchronization.

[0249] For example, during uplink synchronization, if the LTM candidate cell configuration information configures area-specific random access resources (ADRs) and these ADRs are active, the terminal can send an ADR preamble to the target cell. Upon detecting the preamble, the target cell determines the TA (Target Acquisition Request) based on it and directly sends a RAR (Range Access Request) carrying the TA to the terminal. If the LTM candidate cell configuration information does not configure ADRs, or if the configured ADRs are not active, the terminal can send a non-ADR preamble to the target cell. Upon detecting the preamble, the target cell determines the TA based on it and sends a RAR carrying the TA to the terminal through the source cell.

[0250] The following situations can be considered as the dedicated area access resource (DAR) being effective: the terminal is located within the area associated with the DARPR, and / or the uplink synchronization time is within the effective period associated with the DARPR. The following situations can be considered as the DARPR not being effective: the terminal is located outside the area associated with the DARPR, and / or the uplink synchronization time is outside the effective period associated with the DARPR.

[0251] If the area-dedicated random access resources corresponding to the target cell are not effective, the terminal may be far away from the target cell. After the target cell determines the TA based on the non-area-dedicated random access resources, it can send the TA to the terminal through the source cell, which can improve the success rate of TA transmission.

[0252] After the synchronization is completed in advance, method 800 enters the LTM switching execution phase, which may include steps S806 to S811.

[0253] S806, the terminal sends an L1 measurement report to the source cell.

[0254] S806 is an optional step. For example, when the measurement report in S801 is an L1 measurement report, the terminal may not execute S806; when the measurement report in S801 is an L3 measurement report, the terminal may execute S806.

[0255] The terminal can send an L1 measurement report to the source cell according to the network's requirements. The L1 measurement report may include measured or predicted values ​​of parameters related to the signal quality of the target cell.

[0256] S807, the source cell performs LTM handover decision.

[0257] The source cell can perform LTM handover decisions based on the synchronization results of S805. Optionally, the source cell can also perform LTM handover decisions based on the L1 measurement report of S806.

[0258] For example, if the synchronization result of S805 is that both uplink and downlink synchronization are successful, the source cell can determine to perform LTM handover; if the synchronization result of S805 is that uplink synchronization and / or downlink synchronization are unsuccessful, the source cell can determine not to perform LTM handover.

[0259] For example, if the synchronization result of S805 is that both uplink and downlink synchronization are successful, and the L1 measurement report indicates that the signal quality of the target cell meets the requirements, the source cell can determine to perform LTM handover; if the L1 measurement report indicates that the signal quality of the target cell does not meet the requirements, the source cell can determine not to perform LTM handover. Optionally, the source cell can perform RRC reconnection with the terminal.

[0260] After the source cell makes an LTM handover decision, it can inform the terminal of the decision result. The following is an example of executing an LTM handover based on the decision result.

[0261] S808, the source cell sends a cell handover command to the terminal.

[0262] The cell handover command instructs the terminal to perform an LTM handover. The cell handover command can be carried in a MAC CE (an example of third information), which can also instruct the terminal whether to send context information or status information for cell handover to the target cell.

[0263] For example, when the transmission path between the target cell and the source cell is long, and the target cell supports receiving context information or status information from the terminal before the handover is completed, the MAC CE can instruct the terminal to send context information or status information directly to the target cell. This eliminates the need for forwarding from the source cell, thereby reducing the mobility interruption time and handover signaling overhead during cell handover.

[0264] For example, when the target cell does not support receiving context information or status information from the terminal before the handover is completed, the MAC CE can instruct the terminal to send context information or status information to the target cell through the source cell, thereby improving the success rate of cell handover.

[0265] S809, the terminal performs LTM handover.

[0266] For example, the terminal switches from the source cell to the target cell and applies the configuration of the target cell.

[0267] S810, the core network performs transmission path and context information updates.

[0268] The source cell can send fourth information to the core network. The fourth information requests the core network to update the terminal's transmission path and context information. Here, the transmission path and context information refer to the transmission path and context information between the core network and the cell. For example, the transmission path can be updated from the path between the core network and the source cell to the path between the core network and the target cell, and the context information related to the transmission path can be updated (such as the IP address associated with the transmission path).

[0269] Optionally, S810 can be executed before S809 and after S807.

[0270] For example, the core network can pre-configure a time offset Δt for the source cell. Δt indicates that the source cell can send the fourth information before sending the cell handover command, where the interval between the fourth information and the cell handover command is Δt.

[0271] After configuring the above intervals, the core network can receive the fourth information before the terminal performs cell handover. In this way, the core network can reserve resources for updating transmission path and context information and advance the transmission time, thereby reducing the mobility interruption time during cell handover.

[0272] S811, the terminal executes a random access procedure.

[0273] S811 is an optional step. For example, when the terminal does not receive the TA from the target cell, and the terminal determines that the early synchronization has failed, it can execute S811, that is, perform random access again based on the triggering of the cell handover command.

[0274] After the LTM switch is completed, method 800 enters the LTM switch completion stage, which may include two steps, S812 and S813.

[0275] S812, the terminal sends a cell handover completion indication message.

[0276] The terminal can send an LTM handover completion indication message (an example of the fifth message) to the target cell. This indication message may carry context information (or status information) related to the LTM handover, which can be forwarded to the core network by the target cell. This context information may include one or more of the following:

[0277] Identification information, location information, quality of service (QoS) information, billing information, security information, and terminal capability information;

[0278] The identification information includes one or more of the following: terminal identifier, session identifier, interface identifier, and tunnel identifier; location information includes one or more of the following: cell identifier, tracking area identifier, wavelet identifier, region identifier, Internet Protocol (IP) address, and other identifiers containing geographic location; QoS information includes one or more of the following: QoS level, priority, forwarding rules, and QoS-to-data radio bearer (DRB) mapping rules; billing information includes one or more of the following: network usage report and subscription package; terminal capability information includes one or more of the following: terminal type, power level, supported handover type, supported number of hybrid automatic repeat request (HARQ) processes, supported carrier aggregation (CA) or dual connectivity (DC), and frequency / polarization capabilities.

[0279] S813 enables the core network, source cell, and target cell to perform backhaul coordination and data forwarding.

[0280] The core network updates the terminal's transmission path and context information based on the cell handover completion indication information. For example, when the terminal does not support DC, the core network can release the transmission path and context information of the source cell and save the transmission path and context information of the target cell; when the terminal supports DC, the core network can include the transmission path and context information of both the source and target cells, so that the terminal can perform data forwarding through backhaul coordination between the source and target cells.

[0281] The communication methods 600 and 800 provided in the embodiments of this application have been described in detail above. Below, another communication method provided in the embodiments of this application is described. In methods 600 and 800, the terminal stores a complete protocol stack and an incomplete protocol stack (including PHY layer, MAC layer, and RLC layer). The complete protocol stack applies the parameters of the source cell, and the incomplete protocol stack applies the parameters of the target cell. The incomplete protocol stack can only be used to access the target cell and cannot be used to send or receive application layer data. Figure 9 In the method 900 shown, the terminal is pre-configured with two complete protocol stacks. One protocol stack applies the parameters of the source cell, and the other protocol stack applies the parameters of the target cell during cell handover. The terminal can establish a PDU session with the target cell based on the complete protocol stack before the cell handover is completed. Based on this PDU session, application layer data can be sent or received in advance, thereby reducing the mobility interruption time during cell handover.

[0282] like Figure 9 As shown, method 900 is executed by the source cell and the terminal respectively, or method 900 is executed by chips applied to the source cell and the terminal respectively. The source cell can be implemented by a node (e.g., gNB, TRP, or DU) with full or partial base station functionality. The following description uses the execution of method 900 by the source cell and the terminal as an example. Method 900 includes the following:

[0283] S910, if the target cell meets the first condition, determine the sixth information, which is used to indicate the activation of the target cell's protocol stack. The target cell's protocol stack includes the PHY layer, MAC layer, RLC layer, PDCP layer, SDAP layer, and RRC layer. The target cell meets the first condition, which includes at least one of the following: the communication delay between the target cell and the source cell is greater than or equal to a first threshold; the target cell's cell bandwidth is less than or equal to a second threshold; the transmission path length between the target cell and the source cell is greater than or equal to a third threshold; or the communication interface between the target cell and the source cell is expired or does not exist.

[0284] The source cell can determine whether the terminal meets the cell handover conditions based on the measurement report. After determining that the terminal meets the cell handover conditions, it determines whether the target cell meets the first condition. If the target cell meets the first condition, it can be called a weakly cooperative cell. It should be noted that a weakly cooperative cell is used to characterize that the communication latency between the target cell and the source cell does not meet the cell handover requirements. A weakly cooperative cell can also be replaced by a non-real-time cooperative cell or other names that express a similar meaning.

[0285] Optionally, the source cell can determine whether the target cell is a weakly cooperative cell based on one or more of the following parameters: inter-cell communication latency, cell bandwidth, and transmission path.

[0286] Optionally, the source cell can determine whether the target cell is a weakly cooperative cell based on the state of the interface between the target cell and the source cell.

[0287] Optionally, the source cell can also determine whether the target cell is a weakly cooperative cell based on the type information sent by the terminal.

[0288] For a specific example of how the source cell determines whether the target cell meets the first condition, please refer to Method 600, which will not be repeated here.

[0289] S920, the source cell sends the sixth information to the terminal.

[0290] The sixth information can be a bit in a DCI, MAC CE, or RRC message. Optionally, when the bit is "0", it indicates that the protocol stack of the target cell is not activated, and when the bit is "1", it indicates that the protocol stack of the target cell is activated.

[0291] This application does not limit the specific form of the sixth information or the message carrying the sixth information.

[0292] S930, the terminal activates the protocol stack of the target cell based on the sixth information.

[0293] Optionally, "activating the protocol stack of the target cell" can also be referred to as "activating the state of the RRC layer of the target cell".

[0294] In traditional cell handover processes, the terminal maintains both a complete protocol stack and an incomplete protocol stack (including PHY, MAC, and RLC layers). The complete protocol stack uses parameters from the source cell, while the incomplete stack uses parameters from the target cell. The incomplete protocol stack can only be used to access the target cell and cannot be used to send or receive application layer data. After the handover is complete, the terminal updates the parameters of the complete protocol stack to those of the target cell before establishing a PDU session based on the complete protocol stack with the target cell. This PDU session is then used to send or receive application layer data. When the source and target cells are of different types, the transmission delay between them is relatively long, requiring the terminal to spend considerable time establishing a PDU session based on the complete protocol stack with the target cell. This results in a prolonged mobile interruption during the cell handover.

[0295] In this embodiment, the terminal is pre-configured (either by the source base station or the core network) with two complete protocol stacks. One protocol stack applies (or configures) the parameters of the source cell, while the other protocol stack is the protocol stack with parameters to be configured (or activated). After receiving the sixth message, the terminal can apply (or configure) the parameters of the target cell in the other protocol stack, that is, activate the target cell's protocol stack. The parameters of the target cell can be included in the sixth message or sent to the terminal by the source cell through other messages.

[0296] Once the target cell's protocol stack is activated, because this is a complete protocol stack (i.e., including the PHY, MAC, RLC, PDCP, SDAP, and RRC layers), the terminal can establish a PDU session with the target cell based on this protocol stack and send or receive application layer data through this PDU session. Since the activation of the target cell's protocol stack occurs before the cell handover is complete, the terminal can send or receive application layer data in advance, thereby reducing the mobility interruption time during cell handover.

[0297] Figure 10 This is a schematic diagram of a cell handover method based on DAPS provided in an embodiment of this application. Figure 10 For example, the source cell is an NTN cell and the target cell is a TN cell.

[0298] The terminal is configured with two protocol stacks, both of which include PHY, MAC, RLC, PDCP, SDAP, and RRC layers. One protocol stack is configured with the parameters of the source cell, while the other can be configured with the parameters of different cells based on handover requirements.

[0299] For example, when a terminal needs to switch from an NTN cell to TN cell 1, the parameters of one of the protocol stacks can be configured to the parameters of TN cell 1; when a terminal needs to switch from an NTN cell to TN cell 2, the parameters of one of the protocol stacks can be configured to the parameters of TN cell 2. After configuring the parameters of TN cell 1 (or TN cell 2), the terminal can establish a complete PDU session with TN cell 1 (or TN cell 2) based on the protocol stack, and send or receive application layer data through the PDU session.

[0300] The following is a brief introduction to the functions of the above protocol stack.

[0301] The main functions of the RRC layer include control plane functions such as system messaging, access control, security management, measurement and reporting, handover, and mobility. The SDAP layer, PDCP layer, RLC layer, MAC layer, and PHY layer are all controlled by the RRC layer.

[0302] The main functions of the SDAP layer include: mapping QoS flows to DRBs, marking QoS flow identifiers in uplink and downlink packets, etc.

[0303] The main functions of the PDCP layer include: maintaining PDCP sequence numbers, compression / decompression of user plane data headers, encryption / decryption, integrity protection / integrity verification, packet duplication, reordering and in-order delivery, out-of-order delivery, and discarding duplicate packets.

[0304] The main functions of the RLC layer include error correction, segmentation and reassembly, resegmentation, and duplicate packet detection.

[0305] The main functions of the MAC layer include: mapping between logical channels and transport channels, multiplexing / demultiplexing, scheduling, HARQ, and setting logical channel priorities.

[0306] The main functions of the PHY layer include encoding / decoding, modulation / demodulation, and resource mapping / de-mapping.

[0307] Both protocol stacks configured in the terminal are associated with multiple RRC states, such as connected (RRC_CONNECTED), inactive (RRC_INACTIVE), and idle (RRC_IDLE). When the terminal activates the cell's protocol stack, the cell's RRC state can be considered to have changed from inactive or idle to connected; when the terminal deactivates the cell's protocol stack, the cell's RRC state can be considered to have changed from connected to inactive or idle.

[0308] The terminal can activate or deactivate the cell's protocol stack as needed.

[0309] For example, the source cell can instruct the terminal to activate the target cell's protocol stack in the first time period and / or the first geographical area through the sixth information. That is, the parameters of the target cell are configured in a protocol stack in the first time period and / or the first geographical area. The first time period can be a time period related to cell handover (e.g., the time period during which the terminal performs uplink synchronization and / or downlink synchronization with the target cell), and the first geographical area can be an area related to cell handover (e.g., the overlapping area of ​​the source cell and the target cell, or an area where the channel quality of the target cell meets the transmission requirements).

[0310] Activating the protocol stack of the target cell in the first time period and / or the first geographical area enables activation of the protocol stack based on cell handover requirements, thereby avoiding the waste of resources caused by the terminal activating the protocol stack of the target cell in advance.

[0311] Optionally, in method 900, the data offloading control point is set in the core network. The source cell can perform:

[0312] Send the seventh message to the core network. The seventh message is used to instruct the core network to determine the data offloading method for the terminal.

[0313] The eighth message is sent to the target cell. This eighth message instructs the core network to determine the data offloading method for the terminal. Data offloading can also be referred to as data forwarding.

[0314] In traditional handover processes, the source cell is responsible for controlling data offloading of the terminal. That is, after the terminal sends data to the source cell, the source cell determines the data transmission path. The source cell can generate control signaling related to data offloading and send this control signaling to the target cell. When the source and target cells are of different types, or when the target cell meets a first condition, the transmission delay of the control signaling related to data offloading is relatively long. For example, the control signaling and / or service data may need to pass through one or more core networks to reach the target cell from the source cell. In this embodiment, the core network is responsible for the terminal's data offloading. The control signaling and / or service data generated by the core network have a shorter latency to reach the target cell, thereby reducing the data forwarding latency during cell handover.

[0315] Optionally, in method 900, after the cell handover is completed, the terminal can deactivate the protocol stack of the source cell.

[0316] "Deactivating the source cell's protocol stack" can also be called "deactivating the source cell's RRC layer state." After the source cell's protocol stack is deactivated, the terminal no longer needs to receive information from the source cell. Therefore, deactivating the source cell's protocol stack after cell handover can reduce the terminal's resource overhead.

[0317] Optionally, in method 900, the terminal may deactivate the protocol stack of the source cell in a second time period and / or a second geographical region.

[0318] The second time period is, for example, the period after cell handover is completed, and the second geographical area is, for example, the area after cell handover is completed (or an area outside the coverage of the source cell, or an area where the channel quality of the source cell does not meet the transmission requirements). The protocol stack of the source cell is deactivated in the second time period and / or the second geographical area. That is, the parameters of the source cell in a set of protocol stacks are deleted (or disabled) in the second time period and / or the second geographical area. This achieves protocol stack activation based on cell handover requirements, thereby avoiding the resource waste caused by the terminal maintaining multiple protocol stacks. Deactivation means not deleting the parameters of the source cell, but no longer using the parameters of the source cell to communicate with the source cell.

[0319] The foregoing has detailed the method examples provided by the embodiments of this application. It is understood that the corresponding apparatus, in order to achieve the above functions, includes hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should readily recognize that, based on the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0320] Figure 11 and Figure 12 These are schematic diagrams illustrating the structures of two communication devices provided in embodiments of this application. These devices can be used to implement the functions of the transmitting end or receiving end in the above method embodiments, and therefore also possess the beneficial effects of the above method embodiments. In the embodiments of this application, these communication devices can be... Figure 1 The terminal shown can also be Figure 1 The base station or core network mentioned above can also be a module (e.g., a chip) applied to the terminal, base station, or core network.

[0321] like Figure 11 As shown, the communication device 1100 includes a processing unit 1110 and a transceiver unit 1120. The transceiver unit 1120 performs receiving and / or output steps under the control of the processing unit 1110. Specifically, the transceiver unit 1120 acts as a transmitting unit when performing the transmitting (or output) step, and as a receiving unit when performing the receiving (or input) step. The communication device 1100 is used to implement... Figure 6 The method embodiments described herein refer to the functions of the source cell or terminal, or the communication device 1100 is used to implement... Figure 8 The method embodiments described herein may involve the functions of the source cell, terminal, target cell, or core network, or the communication device 1100 may be used to implement... Figure 9 The method embodiments describe the functions of the source cell or terminal.

[0322] When the communication device 1100 is used to implement Figure 6 or Figure 8 When the source cell is used in the method embodiment, the processing unit 1110 is used to: determine the first information when the target cell meets the first condition, wherein the first information is information configured by the core network for cell handover, or the first information is pre-configured information for cell handover; the transceiver unit 1120 is used to: send the first information to the terminal.

[0323] The target cell satisfies the first condition, including at least one of the following: the communication delay between the target cell and the source cell is greater than or equal to a first threshold, the cell bandwidth of the target cell is less than or equal to a second threshold, the transmission path length between the target cell and the source cell is greater than or equal to a third threshold, or the communication interface between the target cell and the source cell is expired or does not exist.

[0324] Optionally, the first information includes resource information, which is used to configure or activate the area-specific random access resources corresponding to the target cell, wherein;

[0325] The area-dedicated random access resource corresponding to the target cell is related to the transmission method of the target cell's TA. Wherein, if the target cell meets the first condition, the area-dedicated random access resource is used to instruct the TA to be transmitted directly from the target cell to the terminal; if the target cell does not meet the first condition, the area-dedicated random access resource is used to instruct the TA to be transmitted to the terminal through the source cell; and / or;

[0326] The area-specific random access resources corresponding to the target cell are valid when the terminal is located in the target area, where the target area includes the overlapping area between the target cell and the source cell.

[0327] Optionally, the first information includes time information, which is used to configure or activate the first time period, and the first time period is used for the terminal to perform uplink and downlink synchronization with the target cell.

[0328] Optionally, the time information includes one or more of the length, period, and offset of the first time period.

[0329] Optionally, the transceiver unit 1120 is further configured to: send second information to the terminal, the second information being used to indicate the transmission mode (or reception mode) of the TA, the TA being used by the terminal to perform uplink synchronization with the target cell.

[0330] Optionally, the transceiver unit 1120 is further configured to: receive a TA from the target cell, wherein the area-specific random access resource corresponding to the target cell does not exist or is not effective, or the target cell does not detect the terminal's area-specific preamble; and send a TA to the terminal.

[0331] Optionally, the transceiver unit 1120 is further configured to: send third information to the terminal, the third information including a cell handover command, and context information or status information for instructing the terminal whether to send the target cell for cell handover.

[0332] Optionally, the transceiver unit 1120 is further configured to: send fourth information to the core network before sending third information to the terminal, wherein the fourth information requests an update to the terminal's transmission path and context information (or, status information).

[0333] Optionally, the transceiver unit 1120 is further configured to: receive type information from the terminal, the type information being used to indicate whether the target cell is a TN cell or an NTN cell; the processing unit 1110 is further configured to: determine whether the target cell meets the first condition based on the type information.

[0334] When the communication device 1100 is used to implement Figure 6 or Figure 8 When the terminal functions as described in the embodiment of the method, the transceiver unit 1120 is used to: send type information to the source cell, the type information being used to indicate whether the target cell is a TN cell or an NTN cell; receive first information from the source cell, wherein the source cell and the target cell are of different types, the first information being information configured by the core network for cell handover, or the first information being information pre-configured by the source cell for cell handover; the processing unit 1110 is used to: perform cell handover according to the first information.

[0335] Optionally, the first information includes resource information, which is used to configure or activate the area-specific random access resources corresponding to the target cell;

[0336] The area-dedicated random access resource corresponding to the target cell is related to the transmission method of the target cell's TA. When the target cell meets the first condition, the area-dedicated random access resource is used to instruct the TA to be transmitted directly from the target cell to the terminal. When the target cell does not meet the first condition, the area-dedicated random access resource is used to instruct the TA to be transmitted to the terminal through the source cell. And / or, the area-dedicated random access resource corresponding to the target cell is valid when the terminal is located within the target area, wherein the target area includes the overlapping area of ​​the target cell and the source cell.

[0337] The target cell satisfies the first condition, including at least one of the following: the communication delay between the target cell and the source cell is greater than or equal to a first threshold, the cell bandwidth of the target cell is less than or equal to a second threshold, the transmission path length between the target cell and the source cell is greater than or equal to a third threshold, or the communication interface between the target cell and the source cell is expired or does not exist.

[0338] Optionally, the first information includes time information, which is used to configure or activate the first time period. The processing unit 1110 is also used to perform uplink synchronization and downlink synchronization with the target cell during the first time period.

[0339] Optionally, the time information includes one or more of the length, period, and offset of the first time period.

[0340] In an optional implementation of the second aspect, the transceiver unit 1120 is further configured to: receive second information from the source cell, the second information being used to indicate the transmission mode (or reception mode) of the TA; receive the TA according to the second information; and the processing unit 1110 is specifically configured to: perform uplink synchronization with the target cell according to the TA during a first time period.

[0341] Optionally, the transceiver unit 1120 is specifically used to: receive TA from the target cell based on the second information.

[0342] Optionally, the transceiver unit 1120 is further configured to: receive third information from the source cell, the third information including a cell handover command, and context information or status information for instructing the terminal whether to send the target cell for cell handover; and send the context information or status information according to the third information.

[0343] Optionally, the transceiver unit 1120 is further configured to: send fifth information to the target cell, the fifth information being used to indicate that cell handover has been completed, the fifth information including the terminal's context information or status information.

[0344] When the communication device 1100 is used to implement Figure 6 or Figure 8 When the target cell is used in the method embodiment, the transceiver unit 1120 is used to: receive a preamble from the terminal through the area dedicated random access resource when the target cell meets the first condition, the preamble is used to instruct the target cell to send TA directly to the terminal; and send TA to the terminal according to the preamble, the TA is used for the terminal to perform uplink synchronization with the target cell.

[0345] The target cell satisfies the first condition, including at least one of the following: the communication delay between the target cell and the source cell is greater than or equal to a first threshold, the cell bandwidth of the target cell is less than or equal to a second threshold, the transmission path length between the target cell and the source cell is greater than or equal to a third threshold, or the communication interface between the target cell and the source cell is expired or does not exist.

[0346] Optionally, the transceiver unit 1120 is further configured to: receive fifth information from the terminal, the fifth information being used to indicate that cell handover has been completed, the fifth information including the terminal's context information or status information; and send the terminal's context information or status information to the core network.

[0347] When the communication device 1100 is used to implement Figure 6 or Figure 8 When the core network is used in the embodiment of the method described, the transceiver unit 1120 is used to: receive a request message from the source cell, the request message requesting to obtain first information for cell handover, the first information including resource information and / or time information, the resource information being used to configure or activate the area-specific random access resources corresponding to the target cell, the time information being used to configure or activate a first time period, the first time period being used for the terminal to perform uplink and downlink synchronization with the target cell; and send the first information to the source cell.

[0348] Optionally, the area-dedicated random access resource corresponding to the target cell is related to the transmission method of the target cell's TA, wherein, if the target cell meets the first condition, the area-dedicated random access resource is used to instruct the TA to be transmitted directly from the target cell to the terminal; if the target cell does not meet the first condition, the area-dedicated random access resource is used to instruct the TA to be transmitted to the terminal through the source cell; and / or,

[0349] The area-specific random access resources corresponding to the target cell are valid when the terminal is located in the target area, where the target area includes the overlapping area between the target cell and the source cell.

[0350] Optionally, the time information includes one or more of the length, period, and offset of the first time period.

[0351] Optionally, the transceiver unit 1120 is further configured to: receive fourth information from the source cell, the fourth information requesting an update of the terminal's transmission path and context information (or, status information), the interval between the transmission time of the third information and the transmission time of the fourth information being configured by the core network, and the third information including a cell handover command sent by the source cell to the terminal.

[0352] Optionally, the transceiver unit 1120 is also used to receive context information or status information of the terminal from the target cell.

[0353] When the communication device 1100 is used to implement Figure 9 When the source cell is used in the method embodiment, the transceiver unit 1120 is used to: send sixth information to the terminal when the target cell meets the first condition. The sixth information is used to indicate the activation of the protocol stack of the target cell. The protocol stack of the target cell includes the physical layer, media access control layer, radio link control layer, packet data convergence protocol layer, service data adaptation protocol layer, and radio resource control layer. The target cell is a TN cell and the source cell is an NTN cell; or, the target cell is an NTN cell and the source cell is a TN cell; or, the target cell and the source cell are two NTN cells with different orbits (or altitudes).

[0354] The target cell satisfies the first condition, including at least one of the following: the communication delay between the target cell and the source cell is greater than or equal to a first threshold, the cell bandwidth of the target cell is less than or equal to a second threshold, the transmission path length between the target cell and the source cell is greater than or equal to a third threshold, or the communication interface between the target cell and the source cell is expired or does not exist.

[0355] Optionally, the sixth information is used to indicate the protocol stack for activating the target cell, including: the sixth information is used to indicate the protocol stack for activating the target cell in the first time period and / or the first geographical area.

[0356] Optionally, the transceiver unit 1120 is further configured to: send seventh information to the core network, the seventh information being used to instruct the core network to determine the data offloading method of the terminal; and send eighth information to the target cell, the eighth information being used to instruct the core network to determine the data offloading method of the terminal.

[0357] When the communication device 1100 is used to implement Figure 9 When the terminal functions as described in the method embodiment, the transceiver unit 1120 is used to: receive sixth information from the source cell, the sixth information being used to indicate the activation of the protocol stack of the target cell; the processing unit 1110 is used to: activate the protocol stack of the target cell according to the sixth information; wherein, the protocol stack of the target cell includes the physical layer, media access control layer, radio link control layer, packet data convergence protocol layer, service data adaptation protocol layer, and radio resource control layer; wherein, the target cell is a TN cell and the source cell is an NTN cell; or, the target cell is an NTN cell and the source cell is a TN cell; or, the target cell and the source cell are two NTN cells on different tracks (or at different altitudes).

[0358] Optionally, the processing unit 1110 is specifically used to: activate the protocol stack of the target cell in the first time period and / or the first geographical area according to the sixth information.

[0359] Optionally, the processing unit 1110 is also used to: deactivate the protocol stack of the source cell after the cell handover is completed.

[0360] Optionally, the processing unit 1110 is specifically used to: deactivate the protocol stack of the source cell in the second time period and / or the second geographical area.

[0361] Those skilled in the art will clearly understand that when the communication device 1100 is used to realize the functions of a source cell, terminal, target cell or core network, the specific working process of the communication device 1100 and the technical effects produced by the execution steps can be referred to the description in the corresponding method embodiments above. For the sake of brevity, it will not be repeated here.

[0362] The communication device 1100 can be a terminal or a network device (the network device can be a source base station, a target base station, or a core network device). The processing unit 1110 can be implemented in hardware or software. When implemented in hardware, the processing unit 1110 can be a logic circuit, integrated circuit, etc. When implemented in software, the processing unit 1110 can be a general-purpose processor that reads software code stored in a storage unit. This storage unit can be integrated into the processing unit 1110 or located outside the processing unit 1110 and exist independently.

[0363] like Figure 12 As shown, the communication device 1200 includes a processor 1210 and an interface circuit 1220, which are coupled to each other. It is understood that the interface circuit 1220 can be a transceiver or an input / output interface. Optionally, the communication device 1200 may further include a memory 1230 for storing instructions executed by the processor 1210, or storing input data required by the processor 1210 to execute instructions, or storing data generated after the processor 1210 executes instructions.

[0364] When the communication device 1200 is used to implement Figure 6 , Figure 8 or Figure 9 In the method shown, processor 1210 is used to implement the functions of the processing unit 1110, and interface circuit 1220 is used to implement the functions of the transceiver unit 1120.

[0365] When the communication device 1200 is a terminal chip (i.e., a chip applied to a terminal), the terminal chip implements the functions of the terminal in the above method embodiments. The terminal chip receives information from the base station, which can be understood as the information being first received by other modules in the terminal (such as a radio frequency module or antenna), and then sent to the terminal chip by these modules. The terminal chip sends information to the base station, which can be understood as the information being first sent to other modules in the terminal (such as a radio frequency module or antenna), and then sent to the base station by these modules.

[0366] When the communication device 1200 is a network device chip (i.e., a chip applied to a network device), the network device chip implements the functions of the source cell, target cell, or core network in the above method embodiments. The network device chip receives information from the terminal, which can be understood as the information being first received by other modules (such as radio frequency modules or antennas) in the network device, and then sent to the network device chip by these modules. The network device chip sends information to the terminal, which can be understood as the information being sent down to other modules (such as radio frequency modules or antennas) in the network device, and then sent to the terminal by these modules.

[0367] In this application, entity A sends information to entity B, either directly or indirectly through other entities. Similarly, entity B receives information from entity A, either directly or indirectly through other entities. Entities A and B can be RAN nodes, or modules within a RAN node or terminal. Information transmission and reception can be between a RAN node and a terminal, such as between a base station and a terminal; between two RAN nodes, such as between a CU and a DU; or between different modules within a single device, such as between a terminal chip and other modules of the terminal, or between a base station chip and other modules of the base station.

[0368] Embodiments of this application also provide a communication system, which can be one or more of the following communication devices:

[0369] Communication device 1100 for implementing the functions of a source cell; communication device 1100 for implementing the functions of a terminal; communication device 1100 for implementing the functions of a target cell; communication device 1100 for implementing the functions of a core network.

[0370] Embodiments of this application also provide a communication system, which can be one or more of the following communication devices:

[0371] A communication device 1200 for implementing the functions of a source cell; a communication device 1200 for implementing the functions of a terminal; a communication device 1200 for implementing the functions of a target cell; and a communication device 1200 for implementing the functions of a core network.

[0372] The method steps in the embodiments of this application can be implemented in hardware or in software instructions executable by a processor. The software instructions can consist of corresponding software modules, which can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, portable hard disks, optical disc drives, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. The storage medium can also be a component of the processor. The processor and the storage medium can reside in an application-specific integrated circuit (ASIC). Alternatively, the ASIC can reside in a base station or terminal. The processor and the storage medium can also exist as discrete components in the base station or terminal.

[0373] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of this application are performed entirely or partially. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user equipment, or other programmable device. The computer program or instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program or instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center integrating one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video optical disc; or it can be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both types of storage media.

[0374] Finally, the following points should be noted regarding the embodiments of this application:

[0375] First, in the embodiments of this application, the terms "first," "second," and various numerical designations are used for ease of description and are not intended to limit the scope of the embodiments of this application. The order of the sequence numbers of the above processes does not imply the order of execution; the execution order of each process should be determined by its function and internal logic.

[0376] Second, in the embodiments of this application, "instruction" can include direct and indirect instructions, as well as explicit and implicit instructions. The information indicated by a certain piece of information is called the information to be instructed. In specific implementations, there are many ways to instruct the information to be instructed. For example, the information to be instructed can be directly instructed, such as the information to be instructed itself or its index. The information to be instructed can also be indirectly indicated by instructing other information, where there is a correlation between the other information and the information to be instructed. Furthermore, a part of the information to be instructed can be indicated, while the other parts are known or pre-agreed upon. For example, the indication of the information to be instructed can be achieved by pre-agreed upon (e.g., by a protocol specifying the existence of a certain information element), thereby reducing the instruction overhead to some extent.

[0377] Third, the “protocol” involved in the embodiments of this application may refer to standard protocols in the field of communication, such as the Long Term Evolution (LTE) protocol, the NR protocol, and related protocols in future communication systems. This application does not limit this.

[0378] Fourth, "predefined" or "preconfigured" can be achieved by pre-storing corresponding codes, tables, or other information-indicating mechanisms in the device (e.g., a terminal or base station). This application does not limit the specific implementation method. "Storing" can refer to storing in one or more memories, which can be separate installations or integrated into the processor or communication device; alternatively, some memories can be separate installations, while others are integrated into the processor or communication device. The type of memory can be any form of storage medium, and this application does not limit this.

[0379] Fifth, "at least one" means one or more, while "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, B exists alone, or A and B exist simultaneously. Here, A and B can be a single object or multiple objects. The character " / " generally indicates that the preceding and following related objects have an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, at least one of a, b, and c can mean: a, or, b, or, c, or, a and b, or, a and c, or, b and c, or, a, b, and c. Here, a, b, and c can each be a single object or multiple objects.

[0380] Sixth, in the embodiments of this application, descriptions such as "when," "in the case of," "if," and "if" all refer to the fact that the device (e.g., a terminal or a base station) will make corresponding processing under certain objective circumstances. They are not time limits, nor do they require the device to make a judgment action when implementing it, nor do they imply any other limitations.

[0381] Seventh, in the various embodiments of this application, unless otherwise specified or logically conflicting, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other, and the technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

Claims

1. A communication method, characterized in that, The method is applied to the source cell, and the method includes: If the target cell meets the first condition, first information is determined, wherein the first information is information configured by the core network for cell handover, or the first information is pre-configured information for cell handover. Send the first information to the terminal; Wherein, the target cell satisfies the first condition, including at least one of the following: The communication delay between the target cell and the source cell is greater than or equal to a first threshold, the cell bandwidth of the target cell is less than or equal to a second threshold, the transmission path length between the target cell and the source cell is greater than or equal to a third threshold, or the communication interface between the target cell and the source cell is expired or does not exist.

2. The method according to claim 1, characterized in that, The first information includes resource information, which is used to configure or activate the area-specific random access resources corresponding to the target cell; The area dedicated random access resource corresponding to the target cell is related to the transmission method of the timing advance (TA) of the target cell. When the target cell meets the first condition, the area dedicated random access resource is used to instruct the TA to be sent directly from the target cell to the terminal. And / or, the area-specific random access resources corresponding to the target cell are valid when the terminal is located in the target area, wherein the target area includes the overlapping area of ​​the target cell and the source cell.

3. The method according to claim 1 or 2, characterized in that, The first information includes time information, which is used to configure or activate a first time period, during which the terminal performs uplink and downlink synchronization with the target cell.

4. The method according to claim 3, characterized in that, The time information includes: One or more of the length, period, and offset of the first time period.

5. The method according to claim 3 or 4, characterized in that, Also includes: Send a second message to the terminal, the second message being used to indicate the transmission method of the TA, the TA being used by the terminal to perform uplink synchronization with the target cell.

6. The method according to claim 5, characterized in that, Also includes: The TA is received from the target cell, wherein the area-specific random access resource corresponding to the target cell does not exist or is not effective, or the target cell does not detect the area-specific preamble of the terminal; Send the TA to the terminal.

7. The method according to any one of claims 1 to 6, characterized in that, Also includes: The terminal is sent a third piece of information, which includes a cell handover command and context information or status information for instructing the terminal whether to send the target cell for cell handover.

8. The method according to any one of claims 1 to 7, characterized in that, Also includes: Before sending the third information to the terminal, a fourth information is sent to the core network, wherein the fourth information requests an update to the terminal's transmission path and context information.

9. The method according to any one of claims 1 to 8, characterized in that, Also includes: The terminal receives type information, which indicates whether the target cell is a terrestrial network TN cell or a non-terrestrial network NTN cell. Based on the type information, determine whether the target cell meets the first condition.

10. A communication method, characterized in that, The method is applied to a terminal or a chip of the terminal, and the method includes: Send type information to the source cell, the type information being used to indicate whether the target cell is a terrestrial network TN cell or a non-terrestrial network NTN cell; Receive first information from the source cell, wherein the source cell and the target cell are of different types, and the first information is information configured by the core network for cell handover, or the first information is information pre-configured by the source cell for cell handover; Cell handover is performed based on the first information.

11. The method according to claim 10, characterized in that, The first information includes resource information, which is used to configure or activate the area-specific random access resources corresponding to the target cell; The area dedicated random access resource corresponding to the target cell is related to the transmission method of the timing advance (TA) of the target cell. When the target cell meets the first condition, the area dedicated random access resource is used to instruct the TA to be sent directly from the target cell to the terminal. And / or, the area-specific random access resources corresponding to the target cell are valid when the terminal is located within the target area, wherein the target area includes the overlapping area between the target cell and the source cell; Wherein, the target cell satisfies the first condition, including at least one of the following: The communication delay between the target cell and the source cell is greater than or equal to a first threshold, the cell bandwidth of the target cell is less than or equal to a second threshold, the transmission path length between the target cell and the source cell is greater than or equal to a third threshold, or the communication interface between the target cell and the source cell is expired or does not exist.

12. The method according to claim 10 or 11, characterized in that, The first information includes time information, which is used to configure or activate a first time period. The method further includes: During the first time period, uplink and downlink synchronization are performed with the target cell.

13. The method according to claim 12, characterized in that, The time information includes: One or more of the length, period, and offset of the first time period.

14. The method according to claim 12 or 13, characterized in that, Also includes: Receive second information from the source cell, the second information being used to indicate the transmission method of TA; Receive the TA according to the second information; The uplink and downlink synchronization with the target cell during the first time period includes: During the first time period, uplink synchronization is performed with the target cell based on the TA.

15. The method according to claim 14, characterized in that, Receiving the TA according to the second information includes: Based on the second information, the TA is received from the target cell.

16. The method according to any one of claims 10 to 15, characterized in that, Also includes: The terminal receives third information from the source cell, the third information including a cell handover command and context information or status information for instructing the terminal whether to send cell handover information to the target cell. The context information or the status information is sent based on the third information.

17. The method according to claim 16, characterized in that, Also includes: A fifth message is sent to the target cell, the fifth message indicating that the cell handover has been completed, and the fifth message includes the context information or status information of the terminal.

18. A communication device, characterized in that, include: A module for performing the method according to any one of claims 1 to 9, or a module for performing the method according to any one of claims 10 to 17.

19. A communication device, characterized in that, include: A processor for implementing, via logic circuitry or by executing a computer program or instructions, the method as described in any one of claims 1 to 9, or the method as described in any one of claims 10 to 17; An interface circuit is used to receive signals from other devices and transmit them to the processor, or to send signals from the processor to other devices.

20. A communication system, characterized in that, include: A communication device for performing the method of any one of claims 1 to 9, and / or a communication device for performing the method of any one of claims 10 to 17.

21. The communication system according to claim 20, characterized in that, Also includes: A communication device for implementing the function of the target cell in the method of any one of claims 1 to 9, and / or a communication device for implementing the function of the target cell in the method of any one of claims 10 to 17.

22. The communication system according to claim 20 or 21, characterized in that, Also includes: A communication device for implementing the core network function in the method of any one of claims 1 to 9, and / or a communication device for implementing the core network function in the method of any one of claims 10 to 17.

23. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program or instructions that, when executed by a communication device, implement the method as described in any one of claims 1 to 9, or implement the method as described in any one of claims 10 to 17.

24. A computer program product, characterized in that, The computer program product includes a computer program or instructions that, when executed by a communication device, implement the method as described in any one of claims 1 to 9, or implement the method as described in any one of claims 10 to 17.

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