Cell handover method, communication apparatus and system

Abstract

Provided are a cell handover method, a communication apparatus, and a system. In the method, a first network device sends a handover request message to a second network device, wherein the handover request message is used for requesting to hand over a terminal device to the second network device. When a handover request confirmation message is received from the second network device, a path handover request message is sent to a core network device, wherein the path handover request message is used for requesting to hand over a data transmission path between the terminal device and the core network device to the second network device. The method can complete the handover of the data transmission path between the terminal device and the core network device in advance, alleviate the handover failure problem that may be caused by intermittent connection of ISL transmission or GSL, and improve the success rate of handover of the terminal device to the second network device.

Description

Cell switching method, communication device and system

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on February 29, 2024, with application number 202410245976.9 and application name “A cell switching method, communication device and system”, the entire contents of which are incorporated by reference into this application. Technical Field

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

[0003] Non-terrestrial communication networks (NTNs), encompassing nodes such as satellite networks, high-altitude platforms, and drones, offer advantages such as global coverage, long-distance transmission, flexible networking, easy deployment, and unrestricted geographic presence. They are widely used in a variety of fields, including maritime communications, positioning and navigation, disaster relief, scientific experiments, video broadcasting, and Earth observation. The integration of terrestrial 5G networks and satellite networks, leveraging their strengths and complementing their weaknesses, will form a seamless, integrated global communication network spanning land, sea, air, space, and space, meeting the diverse service needs of users everywhere.

[0004] Generally, satellite communication systems can be divided into staring satellite communication systems (hereinafter referred to as staring systems) and non-staring satellite communication systems (hereinafter referred to as non-staring systems) based on the operating mode of the payload (for example, beam). Staring systems refer to systems in which the satellite dynamically adjusts the beam pointing direction so that the beam covers approximately the same area on the ground over a period of time; non-staring systems refer to systems in which the satellite beam coverage area moves with the satellite over a period of time. Among them, staring systems can include earth-fixed mode or quasi-earth fixed mode; non-staring systems can include earth-moving mode.

[0005] In satellite communication systems (especially earth-fixed scenarios), the movement of satellite nodes can cause group handover (HO) or group reselection problems for terminal devices within a certain area. Currently, NTN handover or reselection is usually designed for transparent satellite scenarios. In regenerative satellite scenarios, handover between different satellites will go through longer inter-satellite links (ISL) and / or ground-satellite links (GSL). Due to the dynamic satellite topology, ISL and / or GSL transmission may experience intermittent connectivity, which may increase end-to-end transmission delay and even cause terminal device handover failure. Summary of the Invention

[0006] The present application provides a cell switching method, a communication device, and a system, which are beneficial to reducing mobile interruption time and improving the success rate of terminal device switching.

[0007] In a first aspect, a cell handover method is provided. The method can be applied to a first network device, and can be executed, for example, by the first network device, or by a component configured in the first network device (such as a processor, chip, or chip system), or by a logic module or software capable of implementing all or part of the functions of the first network device. This application is not limited to this.

[0008] The method includes: sending a switching request message to a second network device, wherein the switching request message is used to request that a terminal device be switched to the second network device, and the second network device is a candidate network device; receiving a switching request confirmation message from the second network device; and sending a path switching request message to a core network device, wherein the path switching request message is used to request that the data transmission path between the terminal device and the core network device be switched to the second network device.

[0009] The terminal device is within the signal coverage of the first network device, or in other words, the first network device can provide network services for the terminal device.

[0010] When the first network device determines that it is necessary to switch the network device for the terminal device based on the measurement report reported by the terminal device, it can determine a candidate network device for the terminal device. As mentioned above, there can be one or more candidate network devices, and the first network device can send a switching request message to each of the one or more candidate network devices (including the second network device) to request that the terminal device be switched to the candidate network device.

[0011] Each candidate network device that receives the handover request message can send a handover request confirmation message to the first network device after determining whether to agree to the terminal device handover. In this article, it is assumed that the second network device agrees to the terminal device handover and sends a handover request confirmation message to the first network device.

[0012] The candidate network device may be one or more. Therefore, the path switching request message may be used to request switching of the data transmission path between the terminal device and the core network device to one or more candidate network devices.

[0013] Among them, the data transmission path between the terminal device and the core network device is switched to the candidate network device, that is, the data transmission path that the terminal device originally used to transmit data between the first network device and the core network device is switched to data transmission between the candidate network device and the core network device, or in other words, the data transmission path between the terminal device and the core network device is switched from the first network device to the candidate network device.

[0014] It is not difficult to see that the path switching request message sent by the above-mentioned first network device to the core network device is sent after the first network device determines the candidate network device that agrees to switch, that is, the switching of the data transmission path between the terminal device and the core network device does not need to wait until the terminal device determines the target network device from the candidate network devices and completes the switch from the first network device to the target network device.

[0015] Based on the above solution, the first network device can determine a candidate network device (including the above-mentioned second network device) for the terminal device when it determines that the terminal device needs to switch but has not switched yet, and request the core network device to switch the data transmission path between the terminal device and the core network device, so as to switch the data transmission path from the first network device to the candidate network device (such as the second network device), without having to wait until the terminal device completes the switch from the source network device (that is, the first network device) to the target network device before switching the data transmission path between the terminal device and the core network device. In this way, the switching of the data transmission path between the terminal device and the core network device can be completed in advance. In general, the switching time (including the switching of the terminal device on the access side and the switching of the data transmission path between the terminal device and the core network device) can be shortened, and the problem of switching failure caused by intermittent connectivity of ISL transmission or GSL can be alleviated, thereby improving the success rate of the terminal device switching to the second network device.

[0016] In combination with the first aspect, in certain implementations of the first aspect, first information is received from the core network device, where the first information is used to indicate a valid period of a first path, and the first path is used for communication between the first network device and the second network device during the valid period; and sending a path switching request message to the core network device includes: sending the path switching request message to the core network device during the valid period.

[0017] The first path refers to a path for communication between the first network device and the second network device via the Xn interface. The first path can be used for exchanging data of terminal devices between the first network device and the second network device.

[0018] The first path is used for communication between the first network device and the second network device during the valid period. That is, during the valid period, the first network device and the second network device can communicate via the first path. However, after the valid period expires, the first network device and the second network device generally cannot communicate via the first path. In other words, the first path generally expires after the valid period expires, and the end time of the valid period can be understood as the expiration time of the first path. The valid period can also be referred to as the effective period, the effective time, etc., without limitation.

[0019] The first network device may determine a candidate network device for the terminal device within the validity period of the first path and request the core network device to switch the data transmission path between the terminal device and the core network device. In other words, the validity period may be used by the first network device to control the timing of sending the path switch request message to the core network device to be no later than the expiration time of the first path.

[0020] In combination with the first aspect, in certain implementations of the first aspect, the context of the terminal device is released after the terminal device completes the switch based on time information, and the time information is used to indicate the time when the first network device releases the context of the terminal device.

[0021] In combination with the first aspect, in some implementations of the first aspect, the path switching request message carries the time information, and the time information is used to indicate the time when the first network device releases the context of the terminal device.

[0022] The time at which the first network device releases the context of the terminal device indicated by the time information may be related to the validity period of the first path. For example, the time may be the expiration time of the validity period, or a time near the expiration time of the validity period. Therefore, the first network device may release the context of the terminal device according to the time information after the terminal device completes the handover. Alternatively, the first network device may release the context of the terminal device according to the validity period of the first path. In other words, the first network device may automatically release the context of the terminal device within the validity period of the first path. Since the validity period of the first path corresponds to the expiration time of the first path, the first network device may automatically release the context of the terminal device according to the time information after the terminal device completes the handover. Alternatively, the first network device may automatically release the context of the terminal device according to the expiration time of the first path. The first network device may automatically release the context of the terminal device before the first path expires, or in other words, the time at which the first network device automatically releases the context of the terminal device is no later than the expiration time of the first path.

[0023] In combination with the first aspect, in some implementations of the first aspect, the path switch request message further indicates the second network device.

[0024] As mentioned above, there may be one or more candidate network devices, and the path switching request message may carry identifiers of the one or more candidate network devices, where the one or more candidate network devices include the second network device.

[0025] When the path switch request message is used to indicate the second network device, it can be indicated by an identifier of the second network device or other information that can be used to identify the second network device, and this application is not limited to this. By indicating the second network device, the core network device can determine to which network device the data transmission path between the terminal device and the core network device is switched.

[0026] In combination with the first aspect, in certain implementations of the first aspect, a path switching request confirmation message is received from the core network device.

[0027] In combination with the first aspect, in some implementations of the first aspect, the path switch request confirmation message is used to indicate an expiration time of a first path between the first network device and the second network device.

[0028] In other words, the expiration time of the first path is related to the validity period of the first path. The expiration time can be, for example, the end time of the validity period. Before the expiration time of the first path expires, the first network device and the second network device can exchange data with the terminal device via the first path. After the expiration time of the first path expires, the first network device stops exchanging data with the terminal device via the first path.

[0029] In a second aspect, a cell handover method is provided. The method can be applied to a core network device. For example, the method can be performed by the core network device, or by a component configured in the core network device (such as a processor, chip, or chip system), or by a logic module or software capable of implementing all or part of the functions of the core network device. This application is not limited to this.

[0030] The method includes: receiving a path switching request message from a first network device, wherein the path switching request message is used to request switching of the data transmission path between the terminal device and the core network device to a second network device, where the second network device is a candidate network device; and sending a path switching request confirmation message to the first network device.

[0031] Based on the above solution, the core network device can agree to switch the data transmission path between the terminal device and the core network device from the first network device to the candidate network device (such as the second network device) after receiving the path switching request message from the first network device, without having to wait until the terminal device completes the switch from the source network device (that is, the first network device) to the target network device before switching the data transmission path between the terminal device and the core network device. In this way, the switching of the data transmission path between the terminal device and the core network device can be completed in advance. In general, the switching time (including the switching of the terminal device on the access side and the switching of the data transmission path between the terminal device and the core network device) can be shortened, alleviating the problem of switching failure caused by intermittent connectivity of ISL transmission or GSL, and improving the success rate of the terminal device switching to the second network device.

[0032] In combination with the second aspect, in some implementations of the second aspect, first information is sent to the first network device, where the first information is used to indicate a valid period of the first path, and the first path is used for communication between the first network device and the second network device during the valid period.

[0033] In combination with the second aspect, in some implementations of the second aspect, the path switching request message carries time information, and the time information is used to indicate the time when the first network device releases the context of the terminal device.

[0034] In combination with the second aspect, in some implementations of the second aspect, the path switch request message further indicates the second network device.

[0035] In combination with the second aspect, in some implementations of the second aspect, the path switching request confirmation message indicates an expiration time of a first path between the first network device and the second network device.

[0036] The various aspects of the second aspect correspond to the various aspects of the first aspect above. Please refer to the relevant descriptions in the first aspect above and no further details will be given.

[0037] In a third aspect, a cell handover method is provided. The method can be applied to a second network device, and can be executed, for example, by the second network device, or by a component configured in the second network device (such as a processor, chip, or chip system), or by a logic module or software capable of implementing all or part of the functions of the second network device. This application is not limited to this.

[0038] The method includes: receiving a path switching request confirmation message from a core network device, wherein the path switching request confirmation message is a response message of the core network device to a path switching request message from a first network device, and the path switching request message is used to request switching of the data transmission path between the terminal device and the core network device to the second network device; and sending the path switching request confirmation message to the first network device.

[0039] Based on the above solution, the second network device can send the path switching request confirmation message from the core network device to the first network device, without the first network device sending the path switching request confirmation message to the second network device. In this way, the time it takes for the second network device to receive the path switching request confirmation message can be shortened, thereby improving the success rate of the terminal device switching to the second network device.

[0040] In combination with the third aspect, in some implementations of the third aspect, the path switching request confirmation message is used to indicate an expiration time of a first path between the first network device and the second network device.

[0041] The failure time of the first path has been described in detail in the first aspect. Please refer to the relevant description in the first aspect and will not be repeated here.

[0042] In combination with the third aspect, in certain implementations of the third aspect, a status report of a sequence number (SN) related to a user data packet (user data packet) is received from a terminal device.

[0043] The SN status report may include the SN number of the last data packet received by the terminal device before switching from the source network device to the target network device. Based on this SN number, the target network device can determine the next data packet to be transmitted, enabling the target network device to promptly transmit data packets not scheduled by the source network device after the handover, thereby ensuring service continuity.

[0044] In a fourth aspect, a cell handover method is provided. The method can be applied to a terminal device, for example, and can be executed by the terminal device, or can be executed by a component configured in the terminal device (such as a processor, chip, chip system, etc.), or can be implemented by a logic module or software that can implement all or part of the functions of the terminal device. This application is not limited to this.

[0045] The method comprises: switching from a first network device to a third network device; and sending a data packet related sequence number SN status report of the terminal device to the third network device.

[0046] Based on the above scheme, the terminal device can switch from the first network device to the target network device (such as the third network device), and send the SN number of the last data packet received by the terminal device before switching from the source network device to the target network device to the third network device, thereby realizing the switching of the terminal device.

[0047] In combination with the fourth aspect, in certain implementations of the fourth aspect, third information is received from the first network device, where the third information is used to indicate at least one candidate network device and at least one quality of service (QoS) corresponding to the at least one candidate network device, and each QoS of the at least one QoS is the QoS carried by the path between the corresponding candidate network device and the first network device.

[0048] The path bearer between the first network device and the candidate network device can be understood as a channel for communication between the first network device and the candidate network device, and the channel can be used for data interaction between the first network device and the candidate network device, such as data interaction between terminal devices. The path bearer can also be referred to as a path, a channel, or a bearer. Since network devices can communicate through the Xn interface, the path bearer can also be referred to as an Xn interface bearer (Xn bearer), or an Xn interface, or an Xn interface path, etc. The QoS of the path bearer can also be referred to as the QoS of the Xn interface bearer, or the bearer QoS, which can be understood as the QoS that the channel can provide.

[0049] It is worth noting that this solution is also applicable to scenarios where network devices communicate through F1 interfaces, E1 interfaces, NG interfaces or other interfaces. Among them, the F1 interface is the interface between the centralized unit (CU) and the distributed unit (DU), the E1 interface is the interface between CUs, and the next generation (NG) interface is the interface between the radio access network and the core network. When the above solution is applied to the F1 interface, E1 interface, NG interface or other interfaces, the at least one QoS can be the QoS carried by each interface corresponding to at least one candidate network device.

[0050] The path between the first network device and each candidate network device in at least one candidate network device may be a path passing through the Xn interface, that is, the above-mentioned at least one QoS may include the QoS carried by the Xn interface between the first network device and each candidate network device in at least one candidate network device.

[0051] Since there may be multiple candidate network devices, the above-mentioned at least one QoS may be multiple QoS. In this case, the multiple QoS may be the same or different, and this application does not limit this.

[0052] The at least one candidate network device may include a second network device. Therefore, the at least one QoS includes the QoS of the path bearer between the first network device and the second network device. In other words, the second information may be used to indicate the QoS of the path bearer (or, the Xn interface bearer) between the first network device and the second network device.

[0053] The QoS of the path bearer may include at least one of delay, packet loss rate, reliability or throughput.

[0054] In combination with the fourth aspect, in certain implementations of the fourth aspect, the third information is also used to indicate the effective period of at least one path, the at least one path corresponds to the at least one candidate network device, and the path corresponding to each candidate network device is used to communicate with the first network device within the corresponding effective period.

[0055] Taking the second network device as an example, the path corresponding to the second network device is the communication path between the first network device and the second network device. The path corresponding to the second network device can be used to communicate with the first network device within the valid period corresponding to the second network device.

[0056] Since there may be multiple candidate network devices, there may be multiple paths between the first network device and the candidate network devices. In this case, the valid time periods of the multiple paths may be the same or different, and this application does not limit this.

[0057] In combination with the fourth aspect, in some implementations of the fourth aspect, the third information is carried in a radio resource control (RRC) reconfiguration message.

[0058] The RRC reconfiguration message also includes the configuration of the candidate cell and the switching execution condition of the terminal device. The switching execution condition may be related to at least one of the location, time or signal quality of the candidate cell.

[0059] In a fifth aspect, a cell handover method is provided. The method can be applied to a first network device, for example, and can be executed by the first network device, or can be executed by a component configured in the first network device (such as a processor, chip, chip system, etc.), or can be implemented by a logic module or software that can implement all or part of the functions of the first network device. This application is not limited to this.

[0060] The method includes: receiving second information from a core network device, the second information is used to indicate at least one QoS, each QoS in the at least one QoS is a QoS carried by a path between the first network device and one of the at least one candidate network devices; and sending third information to a terminal device, the third information is used to indicate the at least one QoS.

[0061] Based on the above solution, the network side can indicate the QoS carried by the path between the first network device and each candidate network device in at least one candidate network device to the terminal device, so that the terminal device can take into account the service QoS requirements when selecting the target network device, that is, it can assist in the switching of the terminal device, which is conducive to ensuring the service QoS requirements of the terminal device and improving the user experience of the terminal device. In addition, the network side can also indicate the valid period of at least one path corresponding to at least one candidate network device to the terminal device, so that the terminal device switches according to the valid period, which is conducive to avoiding switching failures caused by path failures and can improve the success rate of terminal device switching.

[0062] In combination with the fifth aspect, in certain implementations of the fifth aspect, the second information is also used to indicate the valid period of at least one path, the at least one path corresponds to the at least one candidate network device, and the path corresponding to each candidate network device is used to communicate with the first network device within the corresponding valid period; the third information is also used to indicate the valid period of at least one path.

[0063] In combination with the fifth aspect, in certain implementations of the fifth aspect, the second information is mobility control information.

[0064] Optionally, the second information is mobility control information, or is an information element carried in the mobility control information, which is not limited in this application.

[0065] In addition to the validity period of the at least one QoS and at least one path mentioned above, the mobility control information may also include access restrictions of the terminal device, roaming information, etc., which are not limited.

[0066] In combination with the fifth aspect, in certain implementations of the fifth aspect, the third information is carried in an RRC reconfiguration message.

[0067] The various aspects of the fifth aspect correspond to the various aspects of the fourth aspect above. Please refer to the relevant descriptions in the fourth aspect above and no further details will be given.

[0068] In a sixth aspect, a cell handover method is provided. The method can be applied to a terminal device, for example, and can be executed by the terminal device, or can be executed by a component configured in the terminal device (such as a processor, chip, chip system, etc.), or can be implemented by a logic module or software that can implement all or part of the functions of the terminal device. This application is not limited to this.

[0069] The method includes: receiving third information from a first network device, the third information being used to indicate at least one candidate network device and at least one QoS corresponding to the at least one candidate network device, each QoS in the at least one QoS being a QoS carried by a path between the corresponding candidate network device and the first network device; and determining a target network device from the at least one candidate network device based on a service QoS requirement and the at least one QoS.

[0070] Based on the above scheme, the terminal device can receive at least one QoS from the first network device, so that the terminal device can select a target network device from the candidate network devices based on the at least one QoS and the service QoS requirements of the terminal device, thereby achieving successful switching from the first network device to the target network device. This is conducive to ensuring the service QoS requirements of the terminal device and improving the user experience of the terminal device.

[0071] In combination with the sixth aspect, in certain implementations of the sixth aspect, the third information is also used to indicate the effective period of at least one path, the at least one path corresponds to the at least one candidate network device, and the path corresponding to each candidate network device is used to communicate with the first network device within the corresponding effective period.

[0072] In combination with the sixth aspect, in certain implementations of the sixth aspect, the third information is carried in an RRC reconfiguration message.

[0073] The various aspects of the sixth aspect correspond to the various aspects of the fourth aspect above. Please refer to the relevant descriptions in the fourth aspect above and no further details will be given.

[0074] In a seventh aspect, a cell handover method is provided. The method can be applied to a core network device. The method can be performed by the core network device, or by a component configured in the core network device (such as a processor, chip, chip system, etc.), or by a logic module or software capable of implementing all or part of the functions of the core network device. This application is not limited to this.

[0075] The method includes: generating second information, where the second information is used to indicate at least one QoS, each QoS in the at least one QoS being a QoS carried by a path between a first network device and one of at least one candidate network devices; and sending the second information to the first network device.

[0076] Based on the above solution, the core network device can send at least one QoS to the first network device to facilitate subsequent assistance to the terminal device in determining the target network device.

[0077] In combination with the seventh aspect, in certain implementations of the seventh aspect, the second information is also used to indicate the valid period of at least one path, the at least one path corresponds to the at least one candidate network device, and the path corresponding to each candidate network device is used to communicate with the first network device within the corresponding valid period.

[0078] The various aspects of the seventh aspect correspond to the various aspects of the fourth aspect above. Please refer to the relevant descriptions in the fourth aspect above and no further details will be given.

[0079] In an eighth aspect, a cell handover method is provided. The method can be applied to a first network device, for example, and can be executed by the first network device, or can be executed by a component configured in the first network device (such as a processor, chip, chip system, etc.), or can be implemented by a logic module or software capable of implementing all or part of the functions of the first network device. This application is not limited to this.

[0080] The method includes: sending an early state transmission message to a second network device, wherein the early state transmission message is used to trigger the second network device to send a path switching request message, wherein the path switching request message is used to request switching of the data transmission path between the terminal device and the core network device to the second network device, and the second network device is a candidate network device; and receiving a path switching request confirmation message from the core network device.

[0081] The terminal device is within the signal coverage of the first network device, or in other words, the first network device can provide network services for the terminal device.

[0082] If the first network device needs to perform early data forwarding for the terminal device, the first network device can send an early status transmission message to the second network device. Early data forwarding is data forwarding performed in advance before the terminal device completes the handover. Therefore, the early status transmission message sent by the first network device can be used to notify the second network device that the first network device will send some of the terminal device's data to the second network device in advance. This partial data can be data for the terminal device that has not been scheduled by the first network device; this partial data can also be understood as data that the first network device has not yet sent to the terminal device and that needs to be sent to the terminal device by the second network device.

[0083] In response to the early status transmission message, the second network device may send a path switch request message to the core network device to request that the data transmission path between the terminal device and the core network device be switched to the second network device. In other words, the early status transmission message triggers the second network device to send the path switch request message to the core network device, or in other words, triggers the second network device to request the core network device to switch the data transmission path between the terminal device and the core network device to the second network device.

[0084] Since the early status transmission message is sent when the first network device performs early data forwarding, and early data forwarding is data forwarding performed before the terminal device completes the switch, the path switching request message triggered by this to be sent by the second network device is also a request sent before the terminal device completes the switch, that is, the switching of the data transmission path between the terminal device and the core network device is advanced.

[0085] The first network device can determine one or more candidate network devices for the terminal device based on the measurement report reported by the terminal device. Therefore, the first network device can send an early status transmission message to the one or more candidate network devices respectively, triggering the one or more candidate network devices to send a path switching request message to the core network device.

[0086] Optionally, the path switching request message further indicates each candidate network device.

[0087] When the above-mentioned path switching request message is used to indicate each candidate network device, it can be indicated by the identifier of each candidate network device or other information that can be used to identify each candidate network device. This application is not limited to this. By indicating each candidate network device, it is convenient for the core network device to determine to which candidate network device the data transmission path between the terminal device and the core network device is to be switched.

[0088] In the cell switching method of an embodiment of the present application, the first network device to which the terminal device is connected can, when it determines that the terminal device needs to switch but has not yet switched, trigger the second network device to request the core network device to switch the data transmission path between the terminal device and the core network device by sending an early status transmission message to the second network device, thereby advancing the switching of the data transmission path between the terminal device and the core network device. In this way, the early switching of the data transmission path between the terminal device and the core network device triggered by the early status transmission message can improve the success rate of the terminal device switching to the second network device.

[0089] In combination with the eighth aspect, in certain implementations of the eighth aspect, the path switching request confirmation message carries the configuration and validity period of the second path, and the second path is a path established after the terminal device completes the switching from the first network device to the second network device and is used for communication between the first network device and the second network device.

[0090] The core network device sends the path switch request confirmation message to the second network device so that the path switch request confirmation message is forwarded to the first network device through the second network device.

[0091] The above-mentioned path switching request confirmation message can carry the configuration and validity period of the second path. The second path is the path established by the core network device after the terminal device completes the switching from the first network device to the second network device and is used for communication between the first network device and the second network device.

[0092] The second path is a new communication path established between the first and second network devices after the original path (e.g., the aforementioned first path) fails. Therefore, the first path can also be referred to as the original path, and the second path can also be referred to as the new path (path_new, P_new). The configuration of the second path can include specific path information for the communication path between the first and second network devices, such as identification information for the second path and / or each hop node in the second path.

[0093] In one possible scenario, there is no gap between the validity period of the new path between the first network device and the second network device and the validity period of the original path. In other words, the validity period of the new path between the first network device and the second network device overlaps with the validity period of the original path, such as partially or completely. During the overlapping period, transmission between the first network device and the second network device can be carried out simultaneously via the new path and the original path. This method of simultaneously transmitting via the original path and the new path is called multi-path coordinated transmission, which facilitates the switching of terminal devices.

[0094] In another possible case, there may be a gap between the validity period of the second path (new path) and the validity period of the original path. This gap can be used to prepare the second path. During this gap, no path is available between the first network device and the second network device, that is, communication is not possible.

[0095] In a ninth aspect, a cell handover method is provided, which can be applied to a second network device. The method can be applied to the second network device, for example, and can be executed by the second network device, or can be executed by a component configured in the second network device (such as a processor, chip, chip system, etc.), and can also be implemented by a logic module or software that can implement all or part of the functions of the second network device. This application is not limited to this.

[0096] The method includes: receiving an early state transmission message from a first network device, the early state transmission message is used to trigger the second network device to send a path switching request message, the path switching request message is used to request switching the data transmission path between the terminal device and the core network device to the second network device, and the second network device is a candidate network device; based on the early state transmission message, sending a path switching request message to the core network device.

[0097] Based on the above solution, the second network device can receive an early status transmission message from the first network device, triggering the second network device to send a path switch request message to the core network device, thereby accelerating the switching of the data transmission path between the terminal device and the core network device. In this way, the path switch request message triggered by the early status transmission message is a multi-path coordinated terminal device switching, which can improve the success rate of terminal device switching to the second network device.

[0098] In combination with the ninth aspect, in certain implementations of the ninth aspect, a path switching request confirmation message is received from a core network device; and the path switching request confirmation message from the core network device is sent to the first network device.

[0099] Various aspects of the ninth aspect correspond to various aspects of the eighth aspect above. Please refer to the relevant descriptions in the eighth aspect above and no further details will be given.

[0100] In a tenth aspect, a cell handover method is provided. The method can be applied to a core network device. The method can be performed by the core network device, or by a component configured in the core network device (such as a processor, chip, chip system, etc.). The method can also be implemented by a logic module or software that can implement all or part of the functions of the core network device. This application is not limited to this.

[0101] The method includes: receiving a path switching request message from a second network device, where the second network device is one of at least one candidate network device, and the path switching request message is used to request switching of the data transmission path between the terminal device and the core network device to the second network device; and sending a path switching request confirmation message to the first network device.

[0102] Based on the above solution, the core network device can send a path switch request confirmation message to the second network device after receiving the path switch request message from the second network device. The path switch request message is sent directly from the second network device to the core network device, rather than from the first network device to the core network device. In this way, the core network device can receive relevant information about the candidate network devices more quickly, improving the success rate of terminal devices switching to the second network device.

[0103] In combination with the tenth aspect, in certain implementations of the tenth aspect, the path switching request confirmation message carries the configuration and validity time of the second path, and the second path is established after the terminal device completes the switching from the first network device to the second network device, and is used for communication between the first network device and the second network device during the validity period.

[0104] The various aspects of the tenth aspect correspond to the various aspects of the eighth aspect above. Please refer to the relevant descriptions in the eighth aspect above and no further details will be given.

[0105] In an eleventh aspect, a communications device is provided that can implement the cell handover method described in aspects 1 to 10 and any possible implementation of aspects 1 to 10. The device includes one or more corresponding functional units or modules for performing the method. The functional units or modules included in the device can be implemented in software and / or hardware.

[0106] In a twelfth aspect, a communication device is provided, comprising at least one processor, wherein the at least one processor is used to execute the cell switching method described in the first to tenth aspects and any possible implementation of the first to tenth aspects.

[0107] Optionally, the apparatus may further include a memory for storing instructions and data. The memory is coupled to the processor, and when the processor executes the instructions stored in the memory, the methods described in the above aspects may be implemented.

[0108] Optionally, the apparatus may further include a communication interface, which is used for the apparatus to communicate with other devices. Exemplarily, the communication interface may be a transceiver, a circuit, a bus, a module, or other types of communication interfaces.

[0109] In the thirteenth aspect, a chip system is provided, which includes at least one processor for supporting the implementation of the functions involved in the above-mentioned first to tenth aspects and any possible implementation methods of the first to tenth aspects, for example, receiving or processing the data and / or information involved in the above-mentioned method.

[0110] In one possible design, the chip system further includes a memory, which is used to store program instructions and data, and the memory is located inside or outside the processor.

[0111] In one possible design, the chip system further includes an interface circuit and / or a power supply circuit, where the interface circuit is used to transmit data and the power supply circuit is used to supply power to the chip system.

[0112] The chip system can be composed of chips, or can include chips and other discrete devices.

[0113] In a fourteenth aspect, a communication system is provided, which includes one or more of the aforementioned first network device, second network device, terminal device or core network device.

[0114] In the fifteenth aspect, a computer-readable storage medium is provided, comprising a computer program, which, when executed on a computer, enables the computer to implement the method in the first to tenth aspects and any possible implementation of the first to tenth aspects.

[0115] In the sixteenth aspect, a computer program product is provided, which includes: a computer program (also referred to as code, or instructions), which, when run, enables a computer to execute the method in the first to tenth aspects and any possible implementation of the first to tenth aspects.

[0116] It should be understood that the eleventh to sixteenth aspects of the present application correspond to the technical solutions of the first to tenth aspects of the present application, and the beneficial effects achieved by each aspect and the corresponding feasible implementation methods are similar and will not be repeated. BRIEF DESCRIPTION OF THE DRAWINGS

[0117] FIG1 is a schematic diagram of a communication system provided in an embodiment of the present application;

[0118] FIG2 is a schematic diagram of a gaze system and a non-gaze system in a communication system provided by an embodiment of the present application;

[0119] FIG3 is a schematic diagram of a group handover of a terminal device according to an embodiment of the present application;

[0120] 4 is a schematic diagram of an Xn interface switching between a source network device and a target network device provided in an embodiment of the present application;

[0121] FIG5 is a schematic flow chart of a cell switching method provided in an embodiment of the present application;

[0122] FIG6 is another schematic flowchart of a cell switching method provided in an embodiment of the present application;

[0123] FIG7 is another schematic flowchart of the cell switching method provided in an embodiment of the present application;

[0124] FIG8 is another schematic flowchart of the cell switching method provided in an embodiment of the present application;

[0125] FIG9 is another schematic flowchart of the cell switching method provided in an embodiment of the present application;

[0126] FIG10 is another schematic flowchart of the cell switching method provided in an embodiment of the present application;

[0127] FIG11 is a schematic block diagram of a communication device provided in an embodiment of the present application;

[0128] FIG12 is another schematic block diagram of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0129] The technical solution in this application will be described below with reference to the accompanying drawings.

[0130] The embodiments of the present application can be applied to non-terrestrial network (NTN) systems such as satellite communication systems, high altitude platform station (HAPS) communications, and drones, for example, integrated communication and navigation (IcaN) systems, global navigation satellite systems (GNSS) and ultra-dense low-orbit satellite communication systems. Satellite communication systems can be integrated with traditional mobile communication systems. For example, the mobile communication system can be a fourth generation (4G) communication system (for example, a long term evolution (LTE) system), a worldwide interoperability for microwave access (WiMAX) communication system, a fifth generation (5G) communication system (for example, a new radio (NR) system), and future communication networks.

[0131] The technical solutions of the embodiments of the present application can also be applied to various communication systems based on non-orthogonal multiple access technology, such as sparse code multiple access (SCMA) system. Of course, SCMA can also be called other names in the field of communications; further, the technical solutions of the embodiments of the present application can be applied to multi-carrier transmission systems that adopt non-orthogonal multiple access technology, such as orthogonal frequency division multiplexing (OFDM), filter bank multi-carrier (FBMC), generalized frequency division multiplexing (GFDM), filtered orthogonal frequency division multiplexing (F-OFDM) system, etc.

[0132] The embodiments of the present application can also be applied to systems such as open access networks (open RAN, O-RAN or ORAN), cloud radio access networks (cloud radio access networks, CRAN), or virtualized radio access networks (virtualized RAN, vRAN), or communication systems that integrate two or more of the above systems.

[0133] Figure 1 shows a schematic diagram of a communication system 100 employing an embodiment of the present application. As shown in Figure 1 , the communication system 100 includes: satellites 110, 120, 130, core network equipment 140, terminal equipment 150, 160, 170, 180, and 190.

[0134] The network side includes satellites 110, 120, and 130, and core network equipment 140. Terminal devices can connect to satellites 110, 120, or 130 wirelessly or by wire. For example, terminal devices 150, 160, and 170 can connect to satellite 110 wirelessly when within the coverage area of ​​satellite 110. Terminal device 180 can connect to satellite 120 wirelessly when within the coverage area of ​​satellite 120. Terminal device 190 can connect to satellite 130 wirelessly when within the coverage area of ​​satellite 130. The service area of ​​a satellite network can be divided into multiple small geographic areas based on geographic location, each of which is called a waveband. Wavebands can be represented by different shapes, such as the ellipse shown in Figure 1.

[0135] It should be understood that each satellite in this satellite communication system (satellite 110, satellite 120, and satellite 130) can provide communication services, navigation services, and positioning services to terminal devices through multiple beams. The satellites in this scenario are low Earth orbit (LEO) satellites. Satellites use multiple beams to cover their service areas, and different beams can communicate through one or more of time division, frequency division, and space division. Satellites communicate wirelessly with terminal devices by broadcasting communication signals and navigation signals, and satellites can also communicate wirelessly with core network equipment.

[0136] The satellite mentioned in the embodiments of the present application may be a satellite base station, an orbital receiver or repeater for relaying information, or a network-side device carried on a satellite.

[0137] It should be understood that satellite communication systems include both transparent and non-transparent satellite architectures. Transparent transmission, also known as bent-pipe transmission, involves signals undergoing only frequency conversion and amplification on the satellite, rendering the satellite transparent to the signal, as if it were not there. Non-transparent transmission, also known as regenerative (on-board access / processing) transmission, involves satellites embodying some or all of the base station functionality. For example, satellites 110 and 120 in Figure 1 represent non-transparent satellite architectures, while satellite 130 represents a transparent satellite architecture.

[0138] It should be understood that the core network device 150 may be an access and mobility management function (AMF) network element, which is primarily used for mobility management and access management, and can be used to implement other functions of the mobility management entity (MME) in addition to session management, such as legal control or access authorization (or authentication). It may also be a user plane function (UPF) network element, which is responsible for forwarding user data. Alternatively, it may be a core network device with other names, which is not limited in the present embodiment.

[0139] It should be understood that the aforementioned network device or terminal device may be configured with multiple antennas, which may include at least one transmitting antenna for sending signals and at least one receiving antenna for receiving signals. Furthermore, the network device or terminal device may additionally include a transmitter chain and a receiver chain. Those skilled in the art will appreciate that each may include multiple components related to signal transmission and reception (e.g., processors, modulators, multiplexers, demodulators, demultiplexers, or antennas). Therefore, the network device and the terminal device may communicate using multi-antenna technology.

[0140] It should be understood that the communication system shown in Figure 1 is only a schematic diagram, and the above communication system may also include other terminal devices and network devices, such as wireless relay devices and wireless backhaul devices, which are not shown in Figure 1. The embodiments of the present application do not limit the number of network devices and terminal devices included in the communication system.

[0141] In the embodiment of the present application, the network device can be any device with wireless transceiver function. The network device includes, but is not limited to, an evolved Node B (eNB), a radio network controller (RNC), a Node B (NB), a base station controller (BSC), a base transceiver station (BTS), a home base station (e.g., a home evolved NodeB, or a home Node B, HNB), a baseband unit (BBU), an access point (AP) in a wireless fidelity (WiFi) system, a wireless relay node, a wireless backhaul node, a transmission point (TP) or a transmission and reception point (TRP), etc. It may also be a gNB in ​​a 5G, such as NR, system, or a transmission point (TRP or TP), one or a group of antenna panels (including multiple antenna panels) of a base station in a 5G system, or a network node constituting a gNB or a transmission point, such as a baseband unit (BBU) or a distributed unit (DU), etc.

[0142] In some deployments, the gNB may include a centralized unit (CU) and a DU. The gNB may also include an active antenna unit (AAU). The CU implements some gNB functions, while the DU implements some gNB functions. For example, the CU may be responsible for processing non-real-time protocols and services, such as the radio resource control (RRC) layer, the service data adaptation protocol (SDAP) layer, and / or the packet data convergence protocol (PDCP) layer. The DU may be responsible for processing physical layer protocols and real-time services. For example, it may implement the functions of the radio link control (RLC) layer, the media access control (MAC) layer, and the physical (PHY) layer. A DU can be connected to only one CU or to multiple CUs, and a CU can be connected to multiple DUs. Communication between the CU and DU can be achieved through the F1 interface. The AAU may implement some physical layer processing functions, RF processing, and active antenna related functions. Since the information of the RRC layer will eventually be delivered to the PHY layer and become the information of the PHY layer, or converted from the information of the PHY layer, therefore, in this architecture, high-layer signaling, such as RRC layer signaling, can also be considered to be sent by DU, or by DU+AAU.

[0143] It is understood that the network device may include one or more of a CU node, a DU node, and an AAU node. In addition, the CU may be classified as a network device in an access network (RAN) or a network device in a core network (CN), which is not limited in this application.

[0144] In different systems, CU (or CU-CP, CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meanings. For example, in the O-RAN system, CU may also be called O-CU (Open CU), DU may also be called O-DU (Open DU), CU-CP may also be called O-CU-CP, CU-UP may also be called O-CU-UP, and RU may also be called O-RU. For the convenience of description, this application uses CU, CU-CP, CU-UP, DU, and RU as examples for description.

[0145] Any of the CU (or CU-CP, CU-UP), DU and RU in this application can be implemented through a software module, a hardware module, or a combination of a software module and a hardware module.

[0146] Network equipment provides services for cells, and terminal devices communicate with cells through transmission resources allocated by the network equipment (for example, frequency domain resources, or spectrum resources). The cell can belong to a macro base station (for example, a macro eNB or macro gNB), or to a base station corresponding to a small cell. Small cells here can include: metro cells, micro cells, pico cells, femto cells, etc. These small cells have the characteristics of small coverage and low transmission power, and are suitable for providing high-speed data transmission services.

[0147] In an embodiment of the present application, the terminal device may also be referred to as user equipment (UE), access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent or user device.

[0148] The terminal device may be a device that provides voice / data connectivity to users, such as a handheld device or vehicle-mounted device with wireless connection function. At present, some examples of terminals may include: mobile phones, tablet computers, computers with wireless transceiver functions (such as laptops, PDAs, etc.), mobile internet devices (MIDs), virtual reality (VR) devices, augmented reality (AR) devices, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, cellular phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDAs), handheld devices with wireless communication functions, computing devices or other processing devices connected to wireless modems, vehicle-mounted devices, wearable devices, terminal devices in 5G networks or future evolved public land mobile communication networks (PLMNs). terminal equipment in network, PLMN, etc.

[0149] Wearable devices, also known as wearable smart devices, are a general term for wearable devices that use wearable technology to intelligently design and develop wearable devices for daily wear, such as glasses, gloves, watches, clothing, and shoes. Wearable devices are portable devices that are worn directly on the body or integrated into the user's clothing or accessories. Wearable devices are not just hardware devices, but also achieve powerful functions through software support, data interaction, and cloud interaction. In a broad sense, wearable smart devices include those that are fully functional, large in size, and can achieve full or partial functions without relying on smartphones, such as smart watches or smart glasses, as well as those that only focus on a certain type of application function and need to be used in conjunction with other devices such as smartphones, such as various smart bracelets and smart jewelry for vital sign monitoring.

[0150] Furthermore, terminal devices can also be end devices in the Internet of Things (IoT) system. IoT is a crucial component of future information technology development. Its primary technical feature is connecting objects to the Internet through communications technology, thereby enabling intelligent networks that interconnect humans and machines, and objects and things. IoT technology, for example, utilizes narrowband (NB) technology to achieve massive connectivity, deep coverage, and power-saving terminals.

[0151] In addition, terminal devices can also include sensors such as smart printers, train detectors, and gas stations. Their main functions include collecting data (part of the terminal devices), receiving control information and downlink data from network devices, and sending electromagnetic waves to transmit uplink data to network devices.

[0152] In an embodiment of the present application, a terminal device or a network device includes a hardware layer, an operating system layer running on the hardware layer, and an application layer running on the operating system layer. The hardware layer includes hardware such as a central processing unit (CPU), a memory management unit (MMU), and memory (also called main memory). The operating system can be any one or more computer operating systems that implement business processing through processes, such as a Linux operating system, a Unix operating system, an Android operating system, an iOS operating system, or a Windows operating system. The application layer includes applications such as browsers, address books, word processing software, and instant messaging software. In addition, the embodiment of the present application does not specifically limit the specific structure of the execution subject of the method provided in the embodiment of the present application. As long as it is possible to communicate according to the method provided in the embodiment of the present application by running a program that records the code of the method provided in the embodiment of the present application, for example, the execution subject of the method provided in the embodiment of the present application can be a terminal device or a network device, or a functional module in the terminal device or the network device that can call a program and execute the program.

[0153] In addition, various aspects or features of the present application can be implemented as methods, apparatus, or articles of manufacture using standard programming and / or engineering techniques. The term "article of manufacture" as used in this application covers computer programs that can be accessed from any computer-readable device, carrier, or medium. For example, computer-readable media may include, but are not limited to: magnetic storage devices (e.g., hard disks, floppy disks, or magnetic tapes, etc.), optical disks (e.g., compact discs (CDs), digital versatile discs (DVDs), etc.), smart cards, and flash memory devices (e.g., erasable programmable read-only memories (EPROMs), cards, sticks, or key drives, etc.). In addition, the various storage media described herein may represent one or more devices and / or other machine-readable media for storing information. The term "machine-readable medium" may include, but is not limited to, wireless channels and various other media capable of storing, containing, and / or carrying instructions and / or data.

[0154] Below, for ease of understanding, the terms involved in the embodiments of the present application are first introduced.

[0155] 1. Non-terrestrial networks (NTN)

[0156] NTN, comprising nodes such as satellite networks, high-altitude platforms, and drones, offers significant advantages, including global coverage, long-distance transmission, flexible networking, easy deployment, and unrestricted geographic presence. It has been widely adopted in a variety of fields, including maritime communications, positioning and navigation, disaster relief, scientific experiments, video broadcasting, and Earth observation. The integration of terrestrial 5G networks and satellite networks, leveraging their strengths and complementing their weaknesses, will form a seamless, integrated global communications network covering land, sea, air, space, and ground, meeting the diverse service needs of users everywhere.

[0157] As an important component of NTN, the next-generation satellite network generally shows an ultra-dense and heterogeneous trend: First, the scale of the satellite network has grown from 66 satellites in the Iridium constellation to 720 satellites in the OneWeb constellation, and eventually extended to the Starlink ultra-dense LEO satellite constellation of more than 12,000; second, the satellite network shows heterogeneous characteristics, evolving from traditional single-layer communication networks to multi-layer communication networks. The functions of communication satellite networks are also becoming more complex and diversified, gradually becoming compatible with and supporting functions such as navigation enhancement, earth observation, and multi-dimensional information on-orbit processing.

[0158] 2. Satellite communication system

[0159] Generally, satellite communication systems can be divided into staring satellite communication systems (hereinafter referred to as staring systems) and non-staring satellite communication systems (hereinafter referred to as non-staring systems) based on the operating mode of the payload (e.g., beam). A staring system is a system in which the satellite dynamically adjusts the beam pointing direction over a period of time so that the beam approximately covers the same area on the ground. For example, as shown in Figure 2 (a), the satellite beam coverage moves with the satellite during times T1, T2, and T3. A non-staring system is a system in which the satellite beam coverage moves with the satellite during a period of time. For example, as shown in Figure 2 (b), the satellite dynamically adjusts the beam pointing direction over times T1, T2, and T3 so that the beam approximately covers the same area on the ground during times T1, T2, and T3. A staring system can include an Earth-fixed mode or a quasi-Earth-fixed mode; a non-staring system can include an Earth-mobile mode.

[0160] 3. Mobility Management

[0161] (1) Mobility management issues

[0162] In a satellite communication system (especially an earth-fixed scenario), the movement of satellite nodes may cause group switching or group reselection problems for terminal devices within a certain area's waveband. Figure 3 shows the group switching of a UE cluster over a period of time. Area-1 includes waveband 1, waveband 2, waveband 3, waveband 4, waveband 5, and waveband 6. Area-2 and area-3 may also include 6 wavebands, which will not be repeated here. Wavebands can be represented by different shapes, such as a parallelogram in Figure 3. The UE cluster in a single waveband within area-2 is (user equipment-group 1, UE-G1), and UE-G1 contains multiple UEs. At time T1, UE-G1 is served by one or more beams of satellite-2 (SAT-2); at time T2, the movement of SAT-2 causes the waveband to be unable to be served, and one or more beams of satellite-1 (SAT-1) take over the service of UE-G1. Therefore, a group switching occurs for UE-G1. Furthermore, due to the high satellite speed of approximately 7.5 km / s, group handoffs occur every few to tens of seconds. In other words, in beam-hopping LEO satellite networks, group handoffs driven primarily by network movement are the norm.

[0163] (2) Mobility management methods

[0164] Mobility management mainly includes intra-satellite cell handover, intra-satellite cell reselection, inter-satellite cell handover, inter-satellite cell reselection, registration update, and tracking area update. Taking cell handover (including intra-satellite cell handover and inter-satellite cell handover) as an example, the handover process of the terrestrial network mainly includes the following steps:

[0165] 1) Cell handover measurement: Usually, the network device sends measurement configurations corresponding to multiple cells (including serving cells and neighboring cells) to the terminal device, and the terminal device measures the cell signal quality (such as reference signal received power (RSRP) and / or reference signal received quality (RSRQ)) according to the measurement configuration;

[0166] 2) Measurement result reporting: The terminal device reports the measurement results to the network device. The reporting method can be periodic reporting or event-triggered reporting. In event-triggered reporting, the reporting conditions are usually configured as the serving cell signal quality is less than threshold 1 and / or the neighboring cell signal quality is greater than threshold 2;

[0167] 3) Handover decision: The network device selects an appropriate neighboring cell based on the reported results and exchanges user handover-related context information, admission control, and reserved resources;

[0168] 4) Handover execution: The terminal device receives handover-related control information from the serving cell and completes the access process in the new cell.

[0169] Among them, when the terminal device switches, the random access preamble required is a dedicated preamble reserved by the network device, which is different from the contention-based random access preamble during initial access. In addition, the time domain period of the random access channel (RACH) during switching supports configurations of 10 / 20 / 40 / 80 / 160 milliseconds (ms), which is the same as the RACH period configuration for initial access. It is worth noting that during the switching process, the terminal device's data usually needs to be transferred from the source network device to the target network device to ensure the terminal device's throughput experience.

[0170] Currently, NTN switching or reselection is usually designed for scenarios that occur on transparent satellites. In regenerative scenarios, switching between different satellites will go through longer inter-satellite links (ISLs) and / or ground-satellite links (GSLs). Due to the dynamic nature of satellite topology, ISL and / or GSL transmissions may experience intermittent connectivity, which may increase end-to-end transmission delays and may even cause terminal device switching failures. For example, Figure 4 shows a schematic diagram of Xn interface switching between a source network device 410 and a target network device 420. It can be seen that the source network device 410 and the target network device 420 communicate through one or more relays 430, and the source network device 410, relay 430, and target network device 420 are all network devices deployed on the satellite. Due to the mobility of the satellite, the Xn interface between network devices may be interrupted. Therefore, the ISL transmission between the source network device 410, the relay 430 and the target network device 420 may be intermittent, which may cause the message transmission delay to increase and may even cause the terminal device 450 to fail to switch; the GSL transmission between the source network device 410, the ground station 440 and the target network device 420 may also be intermittent, which may cause the message transmission delay to increase and may even cause the terminal device 450 to fail to switch.

[0171] In view of this, the present application proposes a cell switching method, in which a network device (for example, recorded as a first network device) can request a core network device to switch the data transmission path between the terminal device and the core network device when it determines that the terminal device needs to be switched but has not been switched yet, so as to switch the data transmission path from the first network device to one or more candidate network devices, without having to wait until the terminal device completes the switch from the source network device to the target network device before switching the data transmission path between the terminal device and the core network device. In this way, the switching of the data transmission path between the terminal device and the core network device can be completed in advance. In general, the switching time (including the switching of the terminal device on the access side and the switching of the data transmission path between the terminal device and the core network device) can be shortened, and the problem of switching failure caused by intermittent connectivity of ISL transmission or GSL can be alleviated, thereby improving the success rate of the terminal device switching to the target network device.

[0172] To facilitate understanding of the embodiments of the present application, the following points are first explained:

[0173] First, to facilitate a clear description of the technical solutions of the embodiments of this application, in the embodiments of this application, terms such as "first" and "second" are used to distinguish between identical or similar items with substantially identical functions and effects. For example, the first information and the second information are used solely to distinguish between phase offsets based on the time domain and the frequency domain, and do not limit their order or the number of signaling messages. Those skilled in the art will understand that terms such as "first" and "second" do not limit the number or execution order, and that terms such as "first" and "second" do not necessarily indicate differences.

[0174] Second, "sending" and "receiving" in the embodiments of the present application indicate the direction of signal transmission. Communication between different devices can refer to direct communication between different devices (i.e., without the need for other devices to transfer or forward), or it can also refer to communication between different devices through other devices (i.e., requiring other devices to transfer or forward), or it can also refer to the functional unit inside the device communicating with other devices through another functional unit. That is, in this application, "sending information to the first network device" can be understood as the destination of the information being the first network device, and can include sending information directly or indirectly to the first network device. "Receiving information from the core network device" can be understood as the source of the first information being the core network device, and "receiving information from the core network device" can be understood as the source of the first information being the core network device, and can include receiving information directly or indirectly from the core network device. The information may undergo necessary processing between the source and destination of the information transmission, such as format change, digital-to-analog conversion, etc., but the destination can understand the valid information from the source. Similar expressions in this application can be understood similarly and will not be repeated here.

[0175] Third, in the embodiments of the present application, "at least one" refers to one or more, and "more" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can represent: a; b; c; a and b; a and c; b and c; or a and b and c. Among them, a, b, and c can be single or multiple.

[0176] Fourth, in the embodiments of the present application, "when", "if" and "if" all mean that the device will take corresponding actions under certain objective circumstances, which does not limit the time, nor does it require that the device must perform judgment actions when it is implemented, nor does it mean that there are other limitations.

[0177] The cell switching method and communication device provided by the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the technical solution of the present application can be applied to a wireless communication system, for example, the communication system 100 shown in FIG1 . The communication devices in the wireless communication system may have a wireless communication connection relationship, and the communication device may correspond to the terminal device shown in FIG1 , such as, it may be the terminal device shown in FIG1 , or it may be a chip configured in the terminal device; the communication device may correspond to the network device shown in FIG1 , such as, it may be the network device shown in FIG1 , or it may be a chip configured in the network device; the communication device may correspond to the core network device shown in FIG1 , such as, it may be the core network device shown in FIG1 , or it may be a chip configured in the core network device.

[0178] Below, the method provided by the present application is illustrated through multiple figures. In the embodiments shown in the multiple figures below, each process is described by taking the interaction process between the first network device, the second network device, the terminal device, and the core network device as an example. Among them, the first network device is the source network device of the cell switching, the second network device is the candidate network device of the cell switching, and the third network device is the target network device of the cell switching. It should be understood that the candidate network device can be one or more, and the second network device can be any one of the one or more candidate network devices. The embodiments illustrated in the multiple figures below can be applied to the communication system shown in Figure 1, or can also be applied to other communication systems without limitation.

[0179] FIG5 shows a cell handover method 500 provided in an embodiment of the present application. The method 500 can be applied to inter-satellite cell handover. The method 500 shown in FIG5 includes steps 501 to 503. Each step in the method 500 is described in detail below.

[0180] In step 501, a first network device sends a handover request message (HO request message) to a second network device, wherein the handover request message is used to request handover of a terminal device to the second network device. Correspondingly, the second network device receives the handover request message from the first network device.

[0181] The terminal device is within the signal coverage of the first network device, or in other words, the first network device can provide network services for the terminal device.

[0182] When the first network device determines, based on the measurement report reported by the terminal device, that the network device needs to be switched for the terminal device, it can determine a candidate network device for the terminal device. As described above, there can be one or more candidate network devices, and the first network device can send a switching request message to each of the one or more candidate network devices (including the second network device) to request that the terminal device be switched to the candidate network device.

[0183] In step 502, the first network device receives a handover request confirmation message from the second network device. Accordingly, the second network device sends a handover request confirmation message to the first network device.

[0184] Each candidate network device that receives the handover request message can send a handover request confirmation message to the first network device after determining whether to agree to the terminal device handover. In this article, it is assumed that the second network device agrees to the terminal device handover and sends a handover request confirmation message to the first network device.

[0185] After confirming and agreeing to the terminal device switching, the second network device can perform access control and reserve the cell-radio network temporary identifier (C-RNTI), preamble, random access channel occasion (RO) and time-frequency resources required for the switching.

[0186] In step 503, the first network device sends a path switch request message to the core network device. The path switch request message is used to request that the data transmission path between the terminal device and the core network device be switched to the second network device. Correspondingly, the core network device receives the path switch request message from the first network device.

[0187] As mentioned above, there may be one or more candidate network devices. Therefore, the path switching request message may be used to request switching of the data transmission path between the terminal device and the core network device to one or more candidate network devices.

[0188] Among them, the data transmission path between the terminal device and the core network device is switched to the candidate network device, that is, the data transmission path that the terminal device originally used to transmit data between the first network device and the core network device is switched to data transmission between the candidate network device and the core network device, or in other words, the data transmission path between the terminal device and the core network device is switched from the first network device to the candidate network device.

[0189] It is not difficult to see that the path switching request message sent by the above-mentioned first network device to the core network device is sent after the first network device determines the candidate network device that agrees to be switched, that is, the switching of the data transmission path between the terminal device and the core network device does not need to wait until the terminal device determines the target network device from the candidate network devices and completes the switching from the first network device to the target network device.

[0190] Optionally, the path switching request message indicates the second network device.

[0191] For example, the path switching request message may carry an identifier of the second network device to indicate the second network device through the identifier. The path switching request message may also carry other information that can be used to identify the second network device, which is not limited in this application.

[0192] As mentioned above, there may be one or more candidate network devices, and the path switch request message may further indicate the one or more candidate network devices, where the one or more candidate network devices include the second network device.

[0193] By indicating the one or more candidate network devices, the core network device can determine to which network device the data transmission path between the terminal device and the core network device is switched.

[0194] Based on the above solution, the first network device can determine a candidate network device (including the above-mentioned second network device) for the terminal device when it determines that the terminal device needs to switch but has not switched yet, and request the core network device to switch the data transmission path between the terminal device and the core network device, so as to switch the data transmission path from the first network device to the candidate network device (such as the second network device), without having to wait until the terminal device completes the switch from the source network device (that is, the first network device) to the target network device before switching the data transmission path between the terminal device and the core network device. In this way, the switching of the data transmission path between the terminal device and the core network device can be completed in advance. In general, the switching time (including the switching of the terminal device on the access side and the switching of the data transmission path between the terminal device and the core network device) can be shortened, and the problem of switching failure caused by intermittent connectivity of ISL transmission or GSL can be alleviated, thereby improving the success rate of the terminal device switching to the second network device.

[0195] Optionally, before step 501, the method further includes: the first network device receiving first information from the core network device, the first information being used to indicate a valid period of the first path. Correspondingly, the core network device sends the first information to the first network device.

[0196] The first path refers to a path for communication between the first network device and the second network device via the Xn interface. The first path can be used for exchanging data of terminal devices between the first network device and the second network device.

[0197] The first path is used for communication between the first network device and the second network device during the valid period. That is, during the valid period, the first network device and the second network device can communicate via the first path. However, after the valid period expires, the first network device and the second network device generally cannot communicate via the first path. In other words, the first path generally expires after the valid period expires, and the end time of the valid period can be understood as the expiration time of the first path. The valid period can also be referred to as the effective period, the effective time, etc., without limitation.

[0198] In this embodiment, the first network device may determine a candidate network device for the terminal device within the validity period of the first path and request the core network device to switch the data transmission path between the terminal device and the core network device. In other words, the validity period can be used by the first network device to control the timing of sending the path switch request message to the core network device to be no later than the expiration time of the first path.

[0199] Exemplarily, a possible implementation manner of using the first information to indicate the valid period of the first path is that the first information indicates at least two of the start time, the end time, or the duration of the first path.

[0200] As an optional embodiment, after step 503, the method further includes: the core network device sending a path switch request acknowledgment message (Path Switch Request message ACK) to the first network device. Correspondingly, the first network device receives the path switch request acknowledgment message from the core network device.

[0201] A possible implementation of step 503 is that the core network device sends a path switch request confirmation message to the second network device, so that the path switch request confirmation message is forwarded to the first network device through the second network device.

[0202] Optionally, the path switching request confirmation message is used to indicate an expiration time of the first path between the first network device and the second network device.

[0203] In other words, the expiration time of the first path is related to the validity period of the first path. The expiration time can be, for example, the end time of the validity period. Before the expiration time of the first path expires, the first network device and the second network device can exchange data with the terminal device via the first path. After the expiration time of the first path expires, the first network device stops exchanging data with the terminal device via the first path.

[0204] As an optional embodiment, the method further includes: the first network device releasing the context of the terminal device according to the time information after the terminal device completes the switching, and the time information is used to indicate the time when the first network device releases the context of the terminal device.

[0205] The time at which the first network device releases the context of the terminal device indicated by the time information may be related to the validity period of the first path. For example, the time may be the expiration time of the validity period, or a time near the expiration time of the validity period. Therefore, the first network device may release the context of the terminal device according to the time information after the terminal device completes the handover. Alternatively, the first network device may release the context of the terminal device according to the validity period of the first path. In other words, the first network device may automatically release the context of the terminal device within the validity period of the first path. Since the validity period of the first path corresponds to the expiration time of the first path, the first network device may automatically release the context of the terminal device according to the time information after the terminal device completes the handover. Alternatively, the first network device may automatically release the context of the terminal device according to the expiration time of the first path. The first network device may automatically release the context of the terminal device before the first path expires, or in other words, the time at which the first network device automatically releases the context of the terminal device is no later than the expiration time of the first path.

[0206] Optionally, the path switching request message sent by the first network device to the core network device carries the above time information.

[0207] Of course, if the first network device releases the context of the terminal device according to the valid period of the first path, it can be considered that the core network device knows in advance the time when the first network device releases the context of the terminal device. In this case, the first network device does not need to carry the above time information in the path switching request message.

[0208] After completing a handoff from the source network device to the target network device, the terminal device can send a sequence number (SN) status report to the target network device. This SN status report can include the SN number of the last data packet received by the terminal device before the handoff from the source network device to the target network device. Based on this SN number, the target network device can determine the next data packet to be transmitted, enabling the target network device to promptly transmit data packets not scheduled by the source network device after the handoff, thereby ensuring service continuity.

[0209] In this embodiment, the source network device is the first network device, and the destination network device is the third network device. It will be appreciated that the third network device is one of the one or more candidate network devices described above. Therefore, the third network device and the second network device may be the same network device or different network devices. Optionally, the method further includes: the terminal device sending an SN status report to the third network device. In response, the third network device receives the SN status report containing the sequence number of the user data packet from the terminal device.

[0210] FIG6 shows a cell handover method 600 provided by another embodiment of the present application. The method 600 can be applied to inter-satellite cell handover. The method 600 shown in FIG6 includes steps 601 to 603. Each step in the method 600 is described in detail below.

[0211] In step 601, the core network device generates second information, where the second information is used to indicate at least one QoS, where each QoS in the at least one QoS is a QoS carried by a path between a first network device and one of at least one candidate network device.

[0212] The path bearer between the first network device and the candidate network device can be understood as a channel used for communication between the first network device and the candidate network device. This channel can be used for data exchange between the first network device and the candidate network device, such as data exchange between terminal devices. The path bearer can also be simply referred to as a path, channel, or bearer. Because network devices can communicate via the Xn interface, the path bearer can also be referred to as the Xn interface bearer, Xn interface, or Xn interface path. The QoS of the path bearer can also be referred to as the QoS of the Xn interface bearer or the bearer QoS, which can be understood as the QoS that the channel can provide.

[0213] It is worth noting that this solution is also applicable to scenarios where network devices communicate through F1 interfaces, E1 interfaces, NG interfaces, or other interfaces. The F1 interface is the interface between the CU and the DU, the E1 interface is the interface between CUs, and the NG interface is the interface between the radio access network and the core network. When the above solution is applied to the F1 interface, E1 interface, NG interface, or other interfaces, the at least one QoS can be the QoS carried by each interface corresponding to at least one candidate network device.

[0214] It should be understood that the path between the first network device and each candidate network device in at least one candidate network device can be a path passing through the Xn interface, that is, the above-mentioned at least one QoS can include the QoS carried by the Xn interface between the first network device and each candidate network device in at least one candidate network device.

[0215] It is understandable that, since there may be multiple candidate network devices, the above-mentioned at least one QoS may be multiple QoS. In this case, the multiple QoS may be the same or different, and this application does not limit this.

[0216] In this embodiment, the at least one candidate network device may include a second network device. Therefore, the at least one QoS includes the QoS of the path bearer between the first network device and the second network device. In other words, the second information may be used to indicate the QoS of the path bearer (or, the Xn interface bearer) between the first network device and the second network device.

[0217] The QoS carried by the above path can be related to the service QoS requirements (QoS requirements) of the terminal device. For example, the core network equipment (such as AMF) can map the service QoS requirements of the terminal device into the service level of the Xn interface carrying QoS (such as QoS class identifier (QCI) and scheduling priority (allocation and retention priority), etc.). The above service level may include at least one of latency, packet loss rate, reliability or throughput.

[0218] Optionally, the second information is further used to indicate a valid period of at least one path, where the at least one path corresponds to the at least one candidate network device, and the path corresponding to each candidate network device is used to communicate with the first network device within the corresponding valid period.

[0219] Taking the second network device as an example, the path corresponding to the second network device is the communication path between the first network device and the second network device. The path corresponding to the second network device can be used to communicate with the first network device during the valid period corresponding to the second network device. A more detailed description of the valid period of the path can be found in the relevant description of method 500 above and will not be repeated here.

[0220] In this embodiment, since there may be multiple candidate network devices, there may be multiple paths between the first network device and the candidate network devices. In this case, the valid time periods of the multiple paths may be the same or different, and this application does not limit this.

[0221] In step 602, the core network device sends the second information to the first network device. Correspondingly, the first network device receives the second information from the core network device.

[0222] Optionally, the second information is mobility control information, or is an information element carried in the mobility control information, which is not limited in this application.

[0223] In addition to the validity period of the at least one QoS and at least one path mentioned above, the mobility control information may also include access restrictions of the terminal device, roaming information, etc., which are not limited.

[0224] In step 603, the first network device sends third information to the terminal device, where the third information is used to indicate the at least one QoS. Correspondingly, the terminal device receives the third information from the first network device.

[0225] The terminal device is within the signal coverage of the first network device, or in other words, the first network device can provide network services for the terminal device.

[0226] The third information indicates content corresponding to the second information. For example, the second information indicates the at least one QoS, and the third information also indicates the at least one QoS. For more details about the at least one QoS, please refer to the relevant description in step 601 and will not be repeated here.

[0227] The first network device can forward the received second information directly to the terminal device. In this case, the second information and the third information are the same; the first network device can also generate third information based on the second information and send it to the terminal device, for example, by parsing to obtain at least one QoS in the second information, and then generate third information to indicate the at least one QoS; the first network device can also process the received second information to obtain the third information and then send it to the terminal device. This application does not limit this.

[0228] Optionally, the third information is further used to indicate a valid period of at least one path.

[0229] For more details about the at least one path and the validity period, please refer to the relevant description in step 601. It can be understood that when the second information indicates the validity period of the at least one path, the third information can also indicate the validity period of the at least one path.

[0230] Optionally, the third information is also used to indicate the at least one candidate network device.

[0231] The third information indicating the at least one candidate network device may be implemented by configuring at least one candidate cell. The at least one candidate cell may be a serving cell of the at least one candidate network device, and each candidate network device may provide service for one or more candidate cells.

[0232] Optionally, the third information is carried in an RRC reconfiguration message.

[0233] The RRC reconfiguration message also includes the configuration of the candidate cell and the switching execution condition of the terminal device. The switching execution condition may be related to at least one of the location, time or signal quality of the candidate cell.

[0234] Optionally, after step 602, the method further includes: the terminal device may determine the target network device from at least one candidate network device according to the service QoS requirement and the third information.

[0235] In this embodiment, the first network device is required to select, within the validity period of at least one path corresponding to at least one candidate network device, a path from the at least one path that is highly correlated with the QoS requirements of the terminal device's service, and select the candidate network device corresponding to the path as the target network device. Optionally, the method further includes: the terminal device switching from the source network device to the target network device.

[0236] In this embodiment, the source network device is the first network device, and the target network device can be one of at least one candidate network device, such as a third network device. Therefore, a handover from the source network device to the target network device can also be referred to as a handover from the first network device to the third network device. It should be understood that the third network device can be the second network device, or it can be another network device, without limitation.

[0237] As previously mentioned, the third information also indicates the validity period corresponding to at least one candidate network device. If the terminal device determines that the target network device is the third network device, the terminal device can complete the handover from the first network device to the third network device based on the validity period of the path between the third network device and the first network device. For example, the handover of the terminal device from the first network device to the third network device can be executed no later than the expiration time of the path.

[0238] Based on the above solution, the network side can indicate the QoS carried by the path between the first network device and each candidate network device in at least one candidate network device to the terminal device, so that the terminal device can take into account the service QoS requirements when selecting the target network device, that is, it can assist in the switching of the terminal device, which is conducive to ensuring the service QoS requirements of the terminal device and improving the user experience of the terminal device. In addition, the network side can also indicate the valid period of at least one path corresponding to at least one candidate network device to the terminal device, so that the terminal device switches according to the valid period, which is conducive to avoiding switching failures caused by path failures and can improve the success rate of terminal device switching.

[0239] FIG7 shows a cell handover method 700 provided in another embodiment of the present application. The method 700 can be applied to inter-satellite cell handover. The method 700 shown in FIG7 includes steps 701 to 702. Each step in the method 700 is described in detail below.

[0240] In step 701, a first network device sends an EARLY STATUS TRANSFER message to a second network device. The EARLY STATUS TRANSFER message is used to trigger the second network device to send a path switch request message. The path switch request message is used to request switching the data transmission path between the terminal device and the core network device to the second network device, which is a candidate network device. Correspondingly, the second network device receives the EARLY STATUS TRANSFER message from the first network device.

[0241] The terminal device is within the signal coverage of the first network device, or in other words, the first network device can provide network services for the terminal device.

[0242] In this embodiment, if the first network device needs to perform early data forwarding for the terminal device, the first network device may send an early status transmission message to the second network device. Early data forwarding is data forwarding performed in advance before the terminal device completes handover. Therefore, the early status transmission message sent by the first network device can be used to notify the second network device that the first network device will send some of the terminal device's data to the second network device in advance. This partial data may be data for the terminal device that has not been scheduled by the first network device; this partial data can also be understood as data that the first network device has not yet sent to the terminal device and that needs to be sent to the terminal device by the second network device.

[0243] In step 702, the second network device sends a path switching request message to the core network device.

[0244] In this embodiment, in response to the early status transmission message, the second network device may send a path switch request message to the core network device to request that the data transmission path between the terminal device and the core network device be switched to the second network device. In other words, the early status transmission message triggers the second network device to send the path switch request message to the core network device, or in other words, triggers the second network device to request the core network device to switch the data transmission path between the terminal device and the core network device to the second network device.

[0245] Since the early status transmission message is sent when the first network device performs early data forwarding, and early data forwarding is data forwarding performed before the terminal device completes the switch, the path switching request message triggered by this to be sent by the second network device is also a request sent before the terminal device completes the switch, that is, the switching of the data transmission path between the terminal device and the core network device is advanced.

[0246] The first network device can determine one or more candidate network devices for the terminal device based on the measurement report reported by the terminal device. Therefore, the first network device can send an early status transmission message to the one or more candidate network devices respectively, triggering the one or more candidate network devices to send a path switching request message to the core network device.

[0247] Optionally, the path switching request message further indicates each candidate network device.

[0248] When the above-mentioned path switching request message is used to indicate each candidate network device, it can be indicated by the identifier of each candidate network device or other information that can be used to identify each candidate network device. This application is not limited to this. By indicating each candidate network device, it is convenient for the core network device to determine to which candidate network device the data transmission path between the terminal device and the core network device is to be switched.

[0249] The second network device mentioned above is an example of a candidate network device. Accordingly, the path switching request message also indicates the second network device.

[0250] In step 703, the core network device sends a path switch request confirmation message to the first network device. Correspondingly, the first network device receives the path switch request confirmation message from the core network device.

[0251] In a possible implementation manner of step 703 , the core network device sends the path switch request confirmation message to the second network device so that the path switch request confirmation message is forwarded to the first network device through the second network device.

[0252] As an optional embodiment, the above-mentioned path switching request confirmation message can carry the configuration and validity period of the second path. The second path is a path established by the core network device after the terminal device completes the switching from the first network device to the second network device, and is used for communication between the first network device and the second network device.

[0253] The second path is a new communication path established between the first and second network devices after the original path (e.g., the aforementioned first path) fails. Therefore, the first path can also be referred to as the original path, and the second path can also be referred to as the new path (path_new, P_new). The configuration of the second path can include specific path information for the communication path between the first and second network devices, such as an identifier of the second path and / or each hop node in the second path.

[0254] In one possible scenario, there is no gap between the validity period of the new path between the first network device and the second network device and the validity period of the original path. In other words, the validity period of the new path between the first network device and the second network device overlaps with the validity period of the original path, such as partially or completely. During the overlapping period, transmission between the first network device and the second network device can be carried out simultaneously via the new path and the original path. This method of simultaneously transmitting via the original path and the new path is called multi-path coordinated transmission, which facilitates the switching of terminal devices.

[0255] In another possible case, there may be a gap between the validity period of the second path (new path) and the validity period of the original path. This gap can be used to prepare the second path. During this gap, no path is available between the first network device and the second network device, that is, communication is not possible.

[0256] Based on the above solution, the first network device to which the terminal device is connected can, if it determines that the terminal device needs to switch but has not yet switched, trigger the second network device to request the core network device to switch the data transmission path between the terminal device and the core network device by sending an early status transmission message to the second network device, thereby advancing the switching of the data transmission path between the terminal device and the core network device. In this way, the early switching of the data transmission path between the terminal device and the core network device, triggered by the early status transmission message, can improve the success rate of the terminal device switching to the second network device.

[0257] In order to better understand the method provided by the present application, the following will be combined with a specific switching process to explain the multiple embodiments provided above in more detail. In the processes shown in Figures 8 to 10 below, the communication between the first network device and the second network device is described by taking the existence of a relay node between the two as an example, but this is only shown for ease of understanding and should not constitute any limitation to the present application. There may be more relay nodes between the first network device and the second network device, or there may be no relay node.

[0258] For example, Figure 8 illustrates a cell handover method 800 provided in an embodiment of the present application. This method 800 can be applied to inter-satellite cell handover. The method 800 shown in Figure 8 is based on the method 500 shown in Figure 5 and illustrates a more complete processing logic for the cell handover method. The following description focuses on steps that differ from those in method 500. For steps and terms that are identical to those in method 500, refer to the relevant description of method 500 above and will not be repeated here.

[0259] As shown in the figure, the cell handover method 800 shown in FIG8 includes the following steps:

[0260] In step 801, a core network device sends mobility control information to a first network device. The mobility control information may include access restrictions of terminal devices, roaming information, and information such as a path between the first network device and at least one second network device and a valid period of the path.

[0261] It should be understood that the explanation of the path between the first network device and the at least one second network device and the load carried by the path can be referred to step 601 in FIG. 6 , which will not be repeated here.

[0262] In step 802, the first network device sends a measurement configuration to the terminal device. The measurement configuration may include a measurement frequency, an SSB-based measurement timing configuration (SMTC), measurement reporting conditions (wherein the reporting mode may be periodic reporting, aperiodic reporting, or event-triggered reporting), and measurement objects (such as the locations of the first network device and the second network device, and the signal quality of the first network device and the second network device).

[0263] Illustratively, the measurement reporting condition may be that the signal quality of the first network device is less than a threshold (eg, less than threshold value 1) and / or the signal quality of the second network device is greater than a threshold (eg, greater than threshold value 2).

[0264] In step 803, the terminal device sends a measurement report to the first network device. The measurement report may be obtained by measurement based on the above-mentioned measurement configuration. Exemplarily, the measurement report includes location information and / or signal quality. The location information may include, for example, the global navigation satellite system (GNSS) location of the first network device and each candidate network device, and / or the wave position identification (ID) within the coverage range of the first network device and each candidate network device. The signal quality may, for example, refer to the signal quality of the first network device and each candidate network device.

[0265] Step 804: The first network device makes a conditional handover (CHO) decision based on the measurement report of the terminal device.

[0266] Step 805: The first network device (such as a base station, a satellite, etc.) sends a handover request message to the second network device.

[0267] As mentioned above, the second network device is a candidate network device, and there are one or more candidate network devices. The first network device can send a handover request to the one or more candidate network devices.

[0268] In addition, if there is a relay node between the first network device and a candidate network device (such as the second network device), the first network device may send a handover request message to the candidate network device through the relay node.

[0269] Step 806: After receiving the handover request message, the second network device performs admission control and reserves the C-RNTI, preamble, RO, time-frequency resources, etc. required for the terminal device handover.

[0270] Among the one or more candidate network devices that receive the switching request, if there are one or more candidate network devices (such as the second network device) that agree to the access of the terminal device, then after receiving the switching request, access control can be performed and the C-RNTI, preamble code, RO, time-frequency resources, etc. required for the terminal device switching can be reserved.

[0271] For ease of explanation, the following description takes the second network device as an example of a candidate network device that agrees to allow the terminal device to access.

[0272] Step 807: The second network device sends a handover confirmation (HO ACK) message to the first network device.

[0273] As mentioned above, if there is a relay node between the first network device and the second network device, the second network device may send a handover confirmation message to the first network device through the relay node.

[0274] In step 808, the first network device sends a path switch request message to the core network device within the valid period of the path bearer between the first network device and the second network device. The path switch request message may include an identifier of the second network device and time information (time_release, T_release) (e.g., Coordinated Universal Time (UTC) or a timer) at which the first network device releases the context information of the terminal device. The T_release is used to trigger the first network device to automatically release the context information of the terminal device.

[0275] In step 809 , the core network device sends a path switching request confirmation message to the second network device. The second network device forwards the path switching request confirmation message to the first network device. The message may also carry the expiration time of the path from the first network device to the second network device.

[0276] It should be understood that the failure time of the path from the first network device to the second network device is related to the effective period of the path from the first network device to the second network device. For a detailed explanation of the failure time, please refer to the relevant explanation of Figure 5 above and will not be repeated here.

[0277] Step 810: The core network device completes the path switching.

[0278] The path switching completed by the core network device refers to the switching of the data transmission path between the terminal device and the core network device from the first network device to the second network device. After the path switching is completed, the core network can transmit data to the terminal device through the second network device via the switched data transmission path.

[0279] In step 811, the first network device sends a radio resource control (RRC) reconfiguration message to the terminal device. The RRC reconfiguration message may include a handover execution condition of the terminal device, and the handover execution condition of the terminal device may be related to at least one of location, time, or signal quality.

[0280] Step 812: The terminal device sends an RRC reconfiguration completion message to the first network device.

[0281] Step 813: The terminal device performs CHO according to the CHO condition.

[0282] For example, the terminal device can determine the target network device based on the CHO condition. After determining the target network device, the terminal device leaves the source cell and synchronizes with the target cell, thereby accessing the target cell. Accessing the target cell can adopt a non-contention access or a free access process.

[0283] The non-contention access process may include: the second network device triggering a random access preamble allocation process through a downlink random access indication message. In this embodiment, the second network device may notify the terminal device through RRC signaling to initiate non-contention random access; the terminal device sends a random access request to the second network device, wherein the terminal device initiates the random access request using a specified preamble code on a physical random access channel (PRACH) resource specified by the second network device. If multiple PRACH resources are specified, the terminal device randomly selects a specified PRACH resource in the first available subframe where a PRACH resource exists.

[0284] The difference between the above-mentioned free access process and the above-mentioned non-contention access is that the free access process does not require a designated preamble code to initiate an access request.

[0285] It should be understood that if the terminal device detects that the switching conditions are not met, no switching will be performed.

[0286] Step 814, after the terminal device successfully switches to the second network device, it can actively send an SN status report (status report) related to the user data packet of the terminal device to the second network device. The SN status report may include the SN number of the last data packet successfully received by the terminal device from the first network device before the switching, to assist the second network device in data scheduling for the terminal device.

[0287] Step 815: The first network device releases the context of the terminal device according to the time information.

[0288] Based on the above solution, the first network device can determine a candidate network device (including the above-mentioned second network device) for the terminal device when it determines that the terminal device needs to switch but has not switched yet, and request the core network device to switch the data transmission path between the terminal device and the core network device, so as to switch the data transmission path from the first network device to the candidate network device (such as the second network device), without having to wait until the terminal device completes the switch from the source network device (that is, the first network device) to the target network device before switching the data transmission path between the terminal device and the core network device. In this way, the switching of the data transmission path between the terminal device and the core network device can be completed in advance. In general, the switching time (including the switching of the terminal device on the access side and the switching of the data transmission path between the terminal device and the core network device) can be shortened, and the problem of switching failure caused by intermittent connectivity of ISL transmission or GSL can be alleviated, thereby improving the success rate of the terminal device switching to the second network device.

[0289] For example, Figure 9 illustrates a cell handover method 900 provided in an embodiment of the present application. This method 900 can be applied to inter-satellite cell handover. The method 900 shown in Figure 9 is based on the method 600 shown in Figure 6 and illustrates a more complete processing logic for the cell handover method. The following description focuses on steps that differ from those in method 600. For steps and terms that are identical to those in method 600, refer to the relevant description of method 600 above and will not be repeated here.

[0290] As shown in the figure, the cell switching method 900 shown in FIG9 includes the following steps:

[0291] Step 901: A core network device (such as AMF, UPF, etc.) sends mobility control information to a first network device. The mobility control information may include access restrictions, roaming information, and second information of the terminal device. The second information may include: QoS carried by the path between the first network device and the second network device, where the QoS may include at least one of latency, packet loss rate, reliability, or throughput; and the validity period of the path between the first network device and the second network device (e.g., (start time, end time) ([time_on, time_off], [T_on, T_off])).

[0292] As mentioned above, the second network device is a candidate network device, and there are one or more candidate network devices. Therefore, the mobility control information may include path information between the first network device and one or more candidate network devices.

[0293] It should be understood that the explanation of the path between the first network device and the at least one second network device and the load carried by the path can be referred to step 601 in FIG. 6 , which will not be repeated here.

[0294] The QoS carried by the above path may be related to the service QoS requirements of the terminal device. For related explanations, please refer to the related explanations in FIG. 6 , which will not be repeated here.

[0295] Step 902: The first network device sends a measurement configuration to the terminal device.

[0296] The related explanation of the above measurement configuration can be referred to step 802 in FIG8 , which will not be repeated here.

[0297] Step 903: The terminal device sends a measurement report to the first network device.

[0298] The relevant explanation of the above measurement report can be referred to step 803 in FIG8 , which will not be repeated here.

[0299] Step 904: The first network device makes a conditional handover decision based on the measurement report of the terminal device.

[0300] Step 905: The first network device (such as a base station, a satellite, etc.) sends a handover request to the second network device.

[0301] As mentioned above, the second network device is a candidate network device, and there are one or more candidate network devices. The first network device can send a handover request to the one or more candidate network devices.

[0302] In addition, if there is a relay node between the first network device and a candidate network device (such as the second network device), the first network device may send a handover request message to the candidate network device through the relay node.

[0303] Step 906: After receiving the handover request message, the second network device performs admission control and reserves the C-RNTI, preamble, RO, time-frequency resources, etc. required for the terminal device handover.

[0304] Among the one or more candidate network devices that receive the switching request, if there are one or more candidate network devices (such as the second network device) that agree to the access of the terminal device, then after receiving the switching request message, access control can be performed and the C-RNTI, preamble code, RO, time-frequency resources, etc. required for the terminal device switching can be reserved.

[0305] For ease of explanation, the following description takes the second network device as an example of a candidate network device that agrees to allow the terminal device to access.

[0306] Step 907: The second network device sends a switching confirmation message to the first network device.

[0307] As mentioned above, if there is a relay node between the first network device and the second network device, the second network device may send a handover confirmation message to the first network device through the relay node.

[0308] Step 908: The first network device sends an RRC reconfiguration message to the terminal device. The RRC reconfiguration message may include a handover execution condition for the terminal device and third information. The handover execution condition for the terminal device is related to at least one of the location, time, or signal quality of the second network device. The third information may include the QoS of the path bearer between the first network device and the second network device. The QoS of the path bearer can be used to assist the terminal device in making a cell handover decision (such as the handover timing of the terminal device, the selection of the second network device, etc.). The QoS of the path bearer can also be used to indicate that the conditional handover execution time configured for the terminal device is no later than the end time T_off of the valid period of the above-mentioned path bearer.

[0309] Step 909: The terminal device sends an RRC reconfiguration completion message to the first network device.

[0310] Step 910: The first network device sends an early state transmission message to the second network device and transfers part of the data to the second network device.

[0311] As mentioned above, if there is a relay node between the first network device and the second network device, the first network device can send the early state transmission message to the second network device through the relay node.

[0312] The relevant explanation of some data may refer to the explanation of the data in step 701 of FIG. 7 , which will not be repeated here.

[0313] Step 911: The terminal device may perform CHO according to the CHO condition.

[0314] For example, the terminal device can determine the target network device based on the handover condition. After determining the target network device, the terminal device leaves the source cell and synchronizes with the target cell, thereby accessing the target cell. Accessing the target cell can adopt a non-contention access or a free access process.

[0315] The above-mentioned non-contention access or free access process can refer to the above-mentioned method 800 and will not be repeated here.

[0316] Step 912: The second network device sends a switching success message to the first network device.

[0317] As mentioned above, if there is a relay node between the first network device and the second network device, the second network device may send a handover success message to the first network device through the relay node.

[0318] Step 913: The first network device sends an SN status report related to the user data packet of the terminal device to the second network device.

[0319] As mentioned above, if there is a relay node between the first network device and the second network device, the first network device can send the SN status report information of the terminal device to the second network device through the relay node.

[0320] Step 914: The first network device sends a path switching request message to the core network device.

[0321] Step 915: The core network device completes the path switching.

[0322] The path switching completed by the core network device refers to the switching of the data transmission path between the terminal device and the core network device from the first network device to the second network device. After the path switching is completed, the core network can transmit data to the terminal device through the second network device via the switched data transmission path.

[0323] Step 916: The core network device sends a path switching request confirmation message to the second network device.

[0324] Step 917: The second network device sends information to the first network device requesting the first network device to release the terminal device context.

[0325] As mentioned above, if there is a relay node between the first network device and the second network device, the second network device may send information to the first network device through the relay node, requesting the first network device to release the terminal device context.

[0326] Based on the above solution, the network side can indicate the QoS carried by the path between the first network device and each candidate network device in at least one candidate network device to the terminal device, so that the terminal device can take into account the service QoS requirements when selecting the target network device, that is, it can assist in the switching of the terminal device, which is conducive to ensuring the service QoS requirements of the terminal device and improving the user experience of the terminal device. In addition, the network side can also indicate the valid period of at least one path corresponding to at least one candidate network device to the terminal device, so that the terminal device switches according to the valid period, which is conducive to avoiding switching failures caused by path failures and can improve the success rate of terminal device switching.

[0327] For example, Figure 10 illustrates a cell handover method 1000 provided in an embodiment of the present application. This method 1000 can be applied to inter-satellite cell handover. The method 1000 shown in Figure 10 is based on the method 700 shown in Figure 7 and illustrates a more complete processing logic for the cell handover method. The following description focuses on steps that differ from those in method 700. For steps and terms that are identical to those in method 700, refer to the relevant description of method 700 above and will not be repeated here.

[0328] As shown in the figure, the cell handover method 1000 shown in FIG10 includes the following steps:

[0329] Step 1001: The core network device (such as AMF, UPF, etc.) sends mobility control information to the first network device.

[0330] The relevant explanation of the above mobility control information can refer to step 901 in the above method 900, which will not be repeated here.

[0331] Step 1002: The first network device sends a measurement configuration to the terminal device.

[0332] The related explanation of the above measurement configuration can be referred to step 802 in FIG8 , which will not be repeated here.

[0333] Step 1003: The terminal device sends a measurement report corresponding to the above measurement configuration to the first network device.

[0334] The relevant explanation of the above measurement report can be referred to step 803 in FIG8 , which will not be repeated here.

[0335] Step 1004: The first network device makes a conditional handover decision based on the measurement report of the terminal device.

[0336] Step 1005: The first network device (such as a base station, a satellite, etc.) sends a handover request to the second network device.

[0337] As mentioned above, the second network device is a candidate network device, and there are one or more candidate network devices. The first network device can send a handover request to the one or more candidate network devices.

[0338] In addition, if there is a relay node between the first network device and a candidate network device (such as the second network device), the first network device may send a handover request message to the candidate network device through the relay node.

[0339] Step 1006: After receiving the handover request message, the second network device performs admission control and reserves the C-RNTI, preamble, RO, time-frequency resources, etc. required for the terminal device handover.

[0340] Among the one or more candidate network devices that receive the switching request, if there are one or more candidate network devices (such as the second network device) that agree to the access of the terminal device, then after receiving the switching request, access control can be performed and the C-RNTI, preamble code, RO, time-frequency resources, etc. required for the terminal device switching can be reserved.

[0341] For ease of explanation, the following description takes the second network device as an example of a candidate network device that agrees to allow the terminal device to access.

[0342] Step 1007: The second network device sends a switching confirmation message to the first network device.

[0343] As mentioned above, if there is a relay node between the first network device and the second network device, the second network device may send a handover confirmation message to the first network device through the relay node.

[0344] Step 1008: The first network device sends an RRC reconfiguration message to the terminal device.

[0345] The relevant explanation of the above RRC reconfiguration message can refer to step 908 in the above method 900, which will not be repeated here.

[0346] Step 1009: The terminal device sends an RRC reconfiguration completion message to the first network device.

[0347] Step 1010: The first network device sends an early state transmission message to the second network device and transfers part of the data to the second network device.

[0348] As mentioned above, if there is a relay node between the first network device and the second network device, the first network device can send the early state transmission message to the second network device through the relay node.

[0349] The relevant explanation of some data may refer to the explanation of the data in step 701 of FIG. 7 , which will not be repeated here.

[0350] Step 1011: The second network device sends a path switching request message to the core network device based on the early state transmission message. The path switching request message is used to request switching the data transmission path between the terminal device and the core network device to the second network device.

[0351] Step 1012: The core network device sends a path switch request confirmation message to the second network device, and the second network device sends a path switch request confirmation message to the first network device. The path switch request confirmation message may carry the configuration of the new path (such as the second path) between the first network device and the second network device and the validity period of the new path (for example, (new path start time, new path end time) ([time_on_new, time_off_new], [T_on_new, T_off_new])). There may be a gap between the time of the new path and the original path, and during this gap, neither the new path nor the original path is available.

[0352] As mentioned above, if there is a relay node between the first network device and the second network device, the second network device may send a path switch request confirmation message to the first network device through the relay node.

[0353] Step 1013: The core network device completes the path switching.

[0354] The path switching completed by the core network device refers to the switching of the data transmission path between the terminal device and the core network device from the first network device to the second network device. After the path switching is completed, the core network can transmit data to the terminal device through the second network device via the switched data transmission path.

[0355] Step 1014: The terminal device may perform CHO according to the CHO condition.

[0356] For example, the terminal device can determine the target network device based on the handover condition. After determining the target network device, the terminal device leaves the source cell and synchronizes with the target cell, thereby accessing the target cell. Accessing the target cell can adopt a non-contention access or a free access process.

[0357] The above-mentioned non-contention access or free access process can refer to the method 800 and will not be repeated here.

[0358] Assuming that the original path between the first network device and the second network device fails and a new path becomes effective, the first network device and the second network device can communicate using the new path. Steps 1015 to 1017 below illustrate the steps for communicating using the new path between the first network device and the second network device. For ease of distinction, the steps for communicating using the new path are indicated by dashed lines in the figure.

[0359] Step 1015: The second network device sends a switching completion message to the first network device through the new path.

[0360] As mentioned above, if there is a relay node between the first network device and the second network device, the second network device may send a handover completion message to the first network device through the relay node.

[0361] Step 1016: The first network device sends an SN status report related to the user data packet of the terminal device to the second network device via the new path.

[0362] As mentioned above, if there is a relay node between the first network device and the second network device, the first network device can send the SN status report related to the user data packet of the terminal device to the second network device through the relay node.

[0363] Step 1017: The second network device sends a request message to the first network device through the new path, requesting the first network device to release the context of the terminal device. After receiving the request message, the first network device releases the context of the terminal device.

[0364] As mentioned above, if there is a relay node between the first network device and the second network device, the second network device may send a request message to the first network device through the relay node, requesting the first network device to release the terminal device context.

[0365] Based on the above solution, the first network device to which the terminal device is connected can, if it determines that the terminal device needs to switch but has not yet switched, trigger the second network device to request the core network device to switch the data transmission path between the terminal device and the core network device by sending an early status transmission message to the second network device, thereby advancing the switching of the data transmission path between the terminal device and the core network device. In this way, the early switching of the data transmission path between the terminal device and the core network device, triggered by the early status transmission message, can improve the success rate of the terminal device switching to the second network device.

[0366] It should be understood that the processes shown in Figures 5 to 10 are merely examples and should not constitute any limitation to the present application. In other embodiments, these processes may also include more or fewer steps.

[0367] It should also be understood that the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0368] Receive a path switching request message from a second network device, where the second network device is one of at least one candidate network device, and the path switching request message is used to request switching the data transmission path between the terminal device and the core network device to the second network device. The cell switching method provided in the embodiment of the present application is described in detail with reference to the accompanying drawings. Below, the apparatus provided in the embodiment of the present application is described in detail with reference to the accompanying drawings.

[0369] Figures 11 and 12 are schematic block diagrams of possible communication devices provided in embodiments of the present application. These communication devices can be used to implement the functions of the first network device, the second network device, the terminal device, or the core network device in the above method embodiments, thereby also achieving the beneficial effects of the above method embodiments.

[0370] A communication device provided in this application is shown in FIG11 , where the communication device 1100 includes a communication unit 1110 and a processing unit 1120. The communication unit 1110 may be used to perform receiving or sending actions, and the processing unit 1120 may be used to perform actions other than receiving and sending, such as generating information or messages, processing received information or messages, and so on.

[0371] In one possible design, the communication device 1100 is used to implement the functions of the first network device in any of the method embodiments shown in Figures 5 to 10. For example, the communication device can be the first network device, or a component configured in the first network device (such as a chip, a chip system, a processor, etc.), or a logic module or software capable of implementing some or all of the functions of the first network device.

[0372] Exemplarily, when the communication device 1100 is used to implement the function of method 500, the communication unit 1110 is used to send a switching request message to the second network device, wherein the switching request message is used to request that the terminal device be switched to the second network device, and the second network device is a candidate network device; and is used to receive a switching request confirmation message from the second network device; and is used to send a path switching request message to the core network device, wherein the path switching request message is used to request that the data transmission path between the terminal device and the core network device be switched to the second network device.

[0373] Optionally, the communication unit 1110 is also used to receive first information from the core network device, the first information being used to indicate a valid period of the first path, and the first path being used for communication between the first network device and the second network device during the valid period; and being used to send the path switching request message to the core network device during the valid period.

[0374] Optionally, the processing unit 1120 is configured to release the context of the terminal device after the terminal device completes the switching according to time information, where the time information is used to indicate the time when the first network device releases the context of the terminal device.

[0375] Optionally, the path switching request message carries the time information, and the time information is used to indicate the time when the first network device releases the context of the terminal device.

[0376] Optionally, the path switching request message further indicates the second network device.

[0377] Optionally, the communication unit 1110 is further configured to receive a path switching request confirmation message from the core network device.

[0378] Optionally, the path switching request confirmation message is used to indicate an expiration time of a first path between the first network device and the second network device.

[0379] Exemplarily, when the communication device 1100 is used to implement the function of method 600, the communication unit 1110 is used to receive second information from the core network device, the second information is used to indicate at least one QoS, each QoS of the at least one QoS is the QoS carried by the path between the first network device and one of the at least one candidate network devices; and is used to send third information to the terminal device, the third information is used to indicate the at least one QoS.

[0380] Optionally, the second information is also used to indicate the valid period of at least one path, the at least one path corresponds to the at least one candidate network device, and the path corresponding to each candidate network device is used to communicate with the first network device within the corresponding valid period; the third information is also used to indicate the valid period of at least one path.

[0381] Optionally, the second information is mobility control information.

[0382] Optionally, the third information is carried in an RRC reconfiguration message.

[0383] Exemplarily, when the communication device 1100 is used to implement the function of method 700, the communication unit 1110 is used to send an early status transmission message to the second network device, and the early status transmission message is used to trigger the second network device to send a path switching request message, and the path switching request message is used to request to switch the data transmission path between the terminal device and the core network device to the second network device, and the second network device is a candidate network device; and is used to receive a path switching request confirmation message from the core network device.

[0384] Optionally, the path switching request confirmation message carries the configuration and validity period of the second path, where the second path is a path established after the terminal device completes the switching from the first network device to the second network device and is used for communication between the first network device and the second network device.

[0385] Another possible design is that the communication device 1100 is used to implement the functions of the core network device in any of the method embodiments shown in Figures 5 to 10 above. For example, the communication device can be a core network device, or a component configured in the core network device (such as a chip, chip system, processor, etc.), or a logic module or software that can implement some or all of the functions of the core network device.

[0386] Exemplarily, when the communication device 1100 is used to implement the function of method 500, the communication unit 1110 is used to receive a path switching request message from a first network device, wherein the path switching request message is used to request switching of the data transmission path between the terminal device and the core network device to a second network device, where the second network device is a candidate network device; and to send a path switching request confirmation message to the first network device.

[0387] Optionally, the communication unit 1110 is further configured to send first information to the first network device, where the first information is configured to indicate a valid period of the first path, and the first path is used for communication between the first network device and the second network device during the valid period.

[0388] Optionally, the path switching request message carries time information, and the time information is used to indicate the time when the first network device releases the context of the terminal device.

[0389] Optionally, the path switching request message further indicates the second network device.

[0390] Optionally, the path switching request confirmation message indicates an expiration time of the first path between the first network device and the second network device.

[0391] Exemplarily, when the communication device 1100 is used to implement the function of method 600, the processing unit 1120 is used to generate second information, wherein the second information is used to indicate at least one QoS, each QoS of the at least one QoS being the QoS carried by the path between the first network device and one of the at least one candidate network devices; the sending unit 1110 is used to send the second information to the first network device.

[0392] Optionally, the second information is further used to indicate a valid period of at least one path, the at least one path corresponds to the at least one candidate network device, and the path corresponding to each candidate network device is used for communication with the first network device within the corresponding valid period.

[0393] Exemplarily, when the communication device 1100 is used to implement the function of method 700, the communication unit 1110 is used to receive a path switching request message from a second network device, where the second network device is one of at least one candidate network device, and the path switching request message is used to request switching of the data transmission path between the terminal device and the core network device to the second network device; and to send a path switching request confirmation message to the first network device.

[0394] Optionally, the path switching request confirmation message carries the configuration and validity period of the second path, where the second path is established after the terminal device completes the switch from the first network device to the second network device and is used for communication between the first network device and the second network device during the validity period.

[0395] In another possible design, the communication device 1100 is used to implement the functions of the second network device in any of the method embodiments shown in Figures 5 to 10 above. For example, the communication device can be the second network device, or a component configured in the second network device (such as a chip, a chip system, a processor, etc.), or a logic module or software capable of implementing some or all of the functions of the second network device.

[0396] Exemplarily, when the communication device 1100 is used to implement the function of method 500, the communication unit 1110 is used to receive a path switching request confirmation message from a core network device, where the path switching request confirmation message is a response message of the core network device to a path switching request message from a first network device, and the path switching request message is used to request switching of the data transmission path between the terminal device and the core network device to the second network device; and is used to send the path switching request confirmation message to the first network device.

[0397] Optionally, the path switching request confirmation message is used to indicate an expiration time of a first path between the first network device and the second network device.

[0398] Optionally, the communication unit 1110 is further configured to receive an SN status report from a terminal device.

[0399] Exemplarily, when the communication device 1100 is used to implement the function of method 600, the communication unit 1110 is used to receive third information from the first network device, wherein the third information is used to indicate at least one candidate network device and at least one QoS corresponding to the at least one candidate network device, each QoS in the at least one QoS being the QoS carried by the path between the corresponding candidate network device and the first network device; and is used to determine the target network device from the at least one candidate network device based on the service QoS requirements and the at least one QoS.

[0400] Optionally, the third information is further used to indicate a valid period of at least one path, the at least one path corresponds to the at least one candidate network device, and the path corresponding to each candidate network device is used to communicate with the first network device within the corresponding valid period.

[0401] Optionally, the third information is carried in an RRC reconfiguration message.

[0402] Exemplarily, when the communication device 1100 is used to implement the function of method 700, the communication unit 1110 is used to receive an early status transmission message from the first network device, the early status transmission message is used to trigger the second network device to send a path switching request message, the path switching request message is used to request switching of the data transmission path between the terminal device and the core network device to the second network device, and the second network device is a candidate network device; and is used to send a path switching request message to the core network device based on the early status transmission message.

[0403] Optionally, the communication unit 1110 is further configured to receive a path switch request confirmation message from a core network device; and to send the path switch request confirmation message from the core network device to the first network device.

[0404] In another possible design, the communication device 1100 is used to implement the functions of the terminal device in any of the method embodiments shown in Figures 5 to 10. For example, the communication device can be a terminal device, or a component configured in the terminal device (such as a chip, a chip system, a processor, etc.), or a logic module or software that can implement some or all of the functions of the terminal device.

[0405] Exemplarily, when the communication apparatus 1100 is used to implement the function of the method 500, the processing unit 1120 is used to switch from the first network device to the third network device; the communication unit 1110 is used to send the SN status report of the terminal device to the third network device.

[0406] Optionally, the communication unit 1110 is also used to receive third information from the first network device, wherein the third information is used to indicate at least one candidate network device and at least one QoS corresponding to the at least one candidate network device, each QoS of the at least one QoS being the QoS carried by the path between the corresponding candidate network device and the first network device.

[0407] Optionally, the third information is further used to indicate a valid period of at least one path, the at least one path corresponds to the at least one candidate network device, and the path corresponding to each candidate network device is used to communicate with the first network device within the corresponding valid period.

[0408] Optionally, the third information is carried in an RRC reconfiguration message.

[0409] Exemplarily, when the communication device 1100 is used to implement the function of method 600, the communication unit 1110 is used to receive third information from the first network device, wherein the third information is used to indicate at least one QoS corresponding to at least one candidate network device, and each QoS of the at least one QoS is the QoS carried by the path between the corresponding candidate network device and the first network device; the processing unit 1120 is used to determine the target network device from the at least one candidate network device based on the service QoS requirements and the at least one QoS.

[0410] Optionally, the third information is further used to indicate a valid period of at least one path, the at least one path corresponds to the at least one candidate network device, and the path corresponding to each candidate network device is used to communicate with the first network device within the corresponding valid period.

[0411] Optionally, the third information is carried in an RRC reconfiguration message.

[0412] It is understandable that the division of units in the above-mentioned device is merely a division of logical functions, and each function may correspond to a functional unit, or two or more functions may be integrated into one functional unit. In actual implementation, all or part of the units may be integrated into one physical entity, or distributed across different physical entities. In addition, the above-mentioned functional units may be implemented in the form of hardware, software, or a combination of hardware and software. Whether a function is executed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0413] Another communication device provided by the present application is shown in FIG12 , where the communication device 1200 includes at least one processor 1210. The at least one processor 1210 may be configured to execute computer programs or instructions in a memory to implement the steps performed by the first network device, the second network device, the terminal device, or the core network device in any of the method embodiments shown in FIG5 to FIG10 .

[0414] Optionally, the communication device 1200 may further include at least one memory 1220 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. The at least one processor 1210 and the at least one memory 1220 may be provided separately. For example, each memory may be connected to one or more processors so that the connected processors can read information from the memory and store and / or write information in the memory. Alternatively, the at least one processor 1210 and the at least one memory 1220 may be integrated together, for example, one or more memories may be integrated into a processor.

[0415] Optionally, the communication device 1200 further includes an interface circuit 1230 that can be used to transmit data and / or signaling. The at least one processor 1210 and the interface circuit 1230 are coupled to each other. It is understood that the interface circuit 1230 can be a transceiver, input / output circuit, bus, module, pin, or other type of communication interface, wherein the input circuit of the input / output circuit can be used for receiving, and the output interface can be used for sending.

[0416] Optionally, the communication device 1200 further includes a power supply circuit 1240 , which can be used to supply power to the communication device 1200 .

[0417] When the communication device 1200 is used to implement the methods shown in Figures 5 to 10, the processor 1210 is used to perform the functions of the processing unit described above, and the interface circuit 1220 is used to perform the functions of the receiving unit and / or the transmitting unit described above. Whether the interface circuit 1220 is used for sending or receiving can be determined by whether the communication device 1200 is used to perform a sending action or a receiving action in the solution implemented.

[0418] It is understood that when the communication device 1200 is a communication device (e.g., a first network device, a second network device, a terminal device, or a core network device), the interface circuit 1220 may be a transceiver, specifically including a transmitter and a receiver, where the transmitter is used to transmit signals and the receiver is used to receive signals. When the communication device 1200 is a chip used in a communication device, the interface circuit 1220 may be an input / output circuit, a bus, a module, a pin, or other type of communication interface, where the input circuit in the input / output circuit may be used for receiving and the output interface may be used for transmitting.

[0419] It should be understood that in the communication device 1200 shown in FIG. 12 , the processor 1210 may correspond to the processing unit 1120 in the above communication device 1100 , and the interface circuit 1220 may correspond to the communication unit 1110 in the above communication device 1100 .

[0420] It should also be understood that the coupling in the embodiments of the present application is an indirect coupling or communication connection between devices, units or modules, which can be electrical, mechanical or other forms, and is used for information exchange between devices, units or modules. In the embodiments of the present application, the specific connection medium between the at least one processor 1210, the at least one memory 1220, the interface circuit 1230 and the power supply circuit 1240 is not limited. In Figure 11, the embodiment of the present application shows that the processor 1210, the memory 1220, the interface circuit 1230 and the power supply circuit 1240 are connected via a bus 1250. The bus 1250 is represented by a bold line in Figure 12, and the connection method between other components is only for schematic illustration and is not limited. The bus can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, only one bold line is used in Figure 12, but it does not mean that there is only one bus or one type of bus.

[0421] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0422] The memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct RAM bus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0423] The present application also provides a communication system, which includes one or more of the aforementioned first network device, second network device, terminal device or core network device.

[0424] The present application also provides a computer program product, which includes: a computer program (also referred to as code, or instructions), which, when executed, enables the computer to execute the method executed by the first network device, the method executed by the core network device, the method executed by the second network device, or the method executed by the terminal device in the embodiments shown in Figures 5 to 10.

[0425] The present application also provides a computer-readable storage medium storing a computer program (also referred to as code or instructions). When the computer program is executed, the computer executes the method executed by the first network device, the method executed by the core network device, and the method executed by the second network device or the terminal device in the embodiments shown in Figures 5 to 10.

[0426] The terms "unit," "module," and the like used in this specification may be used to refer to a computer-related entity, hardware, firmware, a combination of hardware and software, software, or software in execution.

[0427] Those skilled in the art will appreciate that the various illustrative logical blocks and steps described in conjunction with the embodiments disclosed herein can be implemented using electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application. In the several embodiments provided in this application, it should be understood that the disclosed devices, equipment, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not performed. In addition, the coupling or direct coupling or communication connection shown or discussed can be through some interface, indirect coupling or communication connection of devices or units, and can be electrical, mechanical, or other forms.

[0428] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units may be selected to achieve the purpose of the solution of this embodiment according to actual needs.

[0429] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0430] In the above embodiments, the functions of each functional unit can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions (programs). When the computer program instructions (program) are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a digital video disc (DVD)), or a semiconductor medium (eg, a solid state disk (SSD)).

[0431] If this function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a ROM, a RAM, a magnetic disk, or an optical disk.

[0432] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A cell handover method, characterized in that: Applied to a first network device, the method includes: Sending a handover request message to the second network device, where the handover request message is used to request that the terminal device be handed over to the second network device, where the second network device is a candidate network device; receiving a handover request confirmation message from the second network device; A path switching request message is sent to the core network device, where the path switching request message is used to request switching the data transmission path between the terminal device and the core network device to the second network device.

2. The method according to claim 1, characterized in that The method further comprises: receiving first information from the core network device, where the first information is used to indicate a valid period of a first path, and the first path is used for communication between the first network device and the second network device during the valid period; The sending of a path switching request message to the core network device includes: During the valid period, the path switching request message is sent to the core network device.

3. The method according to claim 1 or 2, characterized in that The method further comprises: According to the time information, after the terminal device completes the switching, the context of the terminal device is released, and the time information is used to indicate the time when the first network device releases the context of the terminal device.

4. The method according to claim 3, characterized in that The path switching request message carries the time information, and the time information is used to indicate the time when the first network device releases the context of the terminal device.

5. The method according to any one of claims 1 to 4, characterized in that The path switch request message further indicates the second network device.

6. The method according to any one of claims 1 to 5, characterized in that The method further comprises: Receive a path switching request confirmation message from the core network device.

7. The method according to claim 6, characterized in that The path switching request confirmation message is used to indicate the expiration time of the first path between the first network device and the second network device.

8. A cell handover method, characterized in that: Applied to core network equipment, the method includes: receiving a path switching request message from a first network device, wherein the path switching request message is used to request switching of a data transmission path between a terminal device and the core network device to a second network device, where the second network device is a candidate network device; Send a path switching request confirmation message to the first network device.

9. The method according to claim 8, characterized in that The method further comprises: First information is sent to the first network device, where the first information is used to indicate a valid period of a first path, and the first path is used for communication between the first network device and the second network device during the valid period.

10. The method according to claim 8, characterized in that The path switching request message carries time information, and the time information is used to indicate the time when the first network device releases the context of the terminal device.

11. The method according to any one of claims 8 to 10, characterized in that The path switch request message further indicates the second network device.

12. The method according to claim 11, characterized in that The path switch request confirmation message indicates a failure time of a first path between the first network device and the second network device.

13. A cell switching method, characterized in that: Applied to the second network device, the method includes: receiving a path switch request confirmation message from a core network device, where the path switch request confirmation message is a response message of the core network device to a path switch request message from a first network device, wherein the path switch request message is used to request switching of a data transmission path between a terminal device and the core network device to the second network device; The path switching request confirmation message is sent to the first network device.

14. The method according to claim 13, characterized in that The path switching request confirmation message is used to indicate the expiration time of the first path between the first network device and the second network device.

15. The method according to claim 13 or 14, characterized in that The method further comprises: Receive the data packet related sequence number SN status report from the terminal device.

16. A cell switching method, characterized in that: Applied to a terminal device, the method includes: Switching from the first network device to the third network device; Sending an SN status report of the terminal device to the third network device.

17. The method according to claim 16, characterized in that The method further comprises: Receive third information from the first network device, where the third information is used to indicate at least one candidate network device and at least one quality of service (QoS) corresponding to the at least one candidate network device, where each QoS in the at least one QoS is a QoS carried by a path between the corresponding candidate network device and the first network device.

18. The method according to claim 17, characterized in that The third information is further used to indicate a valid period of at least one path, where the at least one path corresponds to the at least one candidate network device, and the path corresponding to each candidate network device is used for communication with the first network device within the corresponding valid period.

19. The method according to claim 17 or 18, characterized in that The third information is carried in a radio resource control RRC reconfiguration message.

20. A cell switching method, characterized in that: Applied to a first network device, the method includes: receiving second information from a core network device, where the second information is used to indicate at least one QoS, where each QoS in the at least one QoS is a QoS carried by a path between the first network device and one of the at least one candidate network devices; Sending third information to the terminal device, where the third information is used to indicate the at least one QoS.

21. The method according to claim 20, characterized in that The second information is further used to indicate a valid period of at least one path, the at least one path corresponding to the at least one candidate network device, and the path corresponding to each candidate network device is used for communication with the first network device within the corresponding valid period; The third information is further used to indicate a valid period of at least one path.

22. The method according to claim 20 or 21, characterized in that The second information is mobility control information.

23. A cell switching method, characterized in that: Applied to a terminal device, the method includes: receiving third information from the first network device, the third information being used to indicate at least one quality of service (QoS) corresponding to at least one candidate network device, each QoS in the at least one QoS being a QoS carried by a path between the corresponding candidate network device and the first network device; A target network device is determined from the at least one candidate network device according to the service QoS requirement and the at least one QoS.

24. The method according to claim 23, wherein The third information is further used to indicate a valid period of at least one path, where the at least one path corresponds to the at least one candidate network device, and the path corresponding to each candidate network device is used for communication with the first network device within the corresponding valid period.

25. The method according to claim 23 or 24, characterized in that The third information is carried in the RRC reconfiguration message.

26. A cell switching method, characterized in that: Applied to core network equipment, the method includes: generating second information, where the second information is used to indicate at least one QoS, where each QoS in the at least one QoS is a QoS carried by a path between the first network device and one of the at least one candidate network devices; The second information is sent to the first network device.

27. The method according to claim 26, characterized in that The second information is further used to indicate a valid period of at least one path, where the at least one path corresponds to the at least one candidate network device, and the path corresponding to each candidate network device is used for communication with the first network device within the corresponding valid period.

28. A cell switching method, characterized in that: Applied to a first network device, the method includes: Sending an early state transfer message to a second network device, where the early state transfer message is used to trigger the second network device to send a path switch request message, where the path switch request message is used to request switching of the data transmission path between the terminal device and the core network device to the second network device, where the second network device is a candidate network device; Receive a path switching request confirmation message from the core network device.

29. The method according to claim 28, characterized in that The path switching request confirmation message carries the configuration and validity period of the second path, where the second path is a path established after the terminal device completes the switching from the first network device to the second network device and is used for communication between the first network device and the second network device.

30. A cell switching method, characterized in that: Applied to the second network device, the method includes: receiving an early state transmission message from a first network device, the early state transmission message being used to trigger the second network device to send a path switch request message, the path switch request message being used to request switching a data transmission path between a terminal device and a core network device to the second network device, where the second network device is a candidate network device; Based on the early state transmission message, a path switching request message is sent to the core network device.

31. The method according to claim 30, wherein The method further comprises: Receive a path switching request confirmation message from a core network device; The path switching request confirmation message from the core network device is sent to the first network device.

32. A cell switching method, characterized in that: Applied to core network equipment, the method includes: receiving a path switching request message from a second network device, where the second network device is one of the at least one candidate network device, and the path switching request message is used to request switching a data transmission path between a terminal device and the core network device to the second network device; A path switching request confirmation message is sent to the first network device.

33. The method according to claim 32, characterized in that The path switching request confirmation message carries the configuration and validity period of the second path, where the second path is a path established after the terminal device completes the switch from the first network device to the second network device and is used for communication between the first network device and the second network device during the validity period.

34. A communication device, characterized in that: include: Unit for implementing the method according to any one of claims 1 to 33.

35. A communication device, characterized in that: include: One or more processors, wherein the one or more processors are configured to execute computer programs or instructions in the memory so that the apparatus performs the method according to any one of claims 1 to 33.

36. A computer-readable storage medium for storing a computer program, characterized in that: The computer program comprises instructions for implementing the method of any one of claims 1 to 33.

37. A computer program product comprising instructions, characterized in that: When the instructions are executed on a computer, the computer is caused to implement the method according to any one of claims 1 to 33.

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