Network switching enhancement method, network system and network node

Abstract

The invention provides a network switching enhancement method executed by a network system. The network switching enhancement method comprises the step that a network node of the network system transmits data to a service / source node and one or more target nodes before a switching process. A network system comprises a network node, a service / source node and / or one or more target nodes. The network node, the service / source node and / or the one or more target nodes are configured to perform the network handover enhancement method.

Description

Technical Field

[0001] This application relates to the field of wireless communication systems, such as non-terrestrial network (NTN) systems, and more specifically, to network handover enhancement methods (e.g., NTN-to-NTN handover), network systems, and network nodes. Background Technology

[0002] The current work involved in this application uses existing methods in new radio (NR) terrestrial networks (TN) and the results of a Rel-17 NR non-terrestrial network (NTN) work item (WI) as the basis for NTN-TN mobility. The mobility-related objectives of this work item include enhancing the measurement / mobility and service continuity of NTN-TN and NTN-NTN, and further enhancing NTN-NTN handover between quasi-fixed and earth-mobile cells in RRC_CONNECTED state to reduce signaling overhead.

[0003] In non-geosynchronous orbit (NGSO) scenarios, satellites (especially low-earth orbit (LEO) satellites) are characterized by high-speed movement. In some scenarios, the relative speed of LEO satellites with respect to the Earth can reach as high as 7.56 kilometers per second (27,216 kilometers per hour), which is approximately 100 times the speed of a high-speed train. Regardless of whether the UE is in motion, this means that in LEO scenarios, almost all UEs in the same cell may experience frequent handovers within a very short period of time. If the existing handover command mechanism is used, it will result in a large amount of signaling overhead, especially since this signaling may burst in a concentrated manner, because the current handover command is carried in the form of an RRCReconfiguration message through dedicated radio resource control (RRC) signaling.

[0004] Signaling bursts pose a challenge to the network because it may not be able to provide sufficient radio resources to transmit handover commands for each relevant UE within a short period of time. This can result in some UEs receiving handover commands later than others, leading to delayed handovers or even handover failures. Therefore, a pressing issue remains: how to reduce the signaling load of handover (HO) commands. Summary of the Invention

[0005] The purpose of this application is to propose a network handover enhancement method, network system, and network node that can reduce signaling load during processes such as NTN-NTN handover.

[0006] In a first aspect of this application, a network handover enhancement method performed by a network system includes: transmitting data by network nodes of the network system to a serving / source node and one or more target nodes prior to the handover process.

[0007] In a second aspect of this application, a network handover enhancement method performed by a network node includes: the network node transmitting data to a serving / source node and one or more target nodes prior to the handover process.

[0008] In a third aspect of this application, a network system includes a network node, a serving / source node, and / or one or more target nodes. The network node, the serving / source node, and / or the one or more target nodes are configured to perform the network handover enhancement method described above.

[0009] In a fourth aspect of this application, a network node includes a memory, a transceiver, and a processor connected to the memory and the transceiver. The transceiver is configured to transmit data to a serving / source node and one or more target nodes prior to a handover process.

[0010] In a fifth aspect of this application, a non-transitory machine-readable storage medium stores instructions that, when executed by a computer, cause the computer to perform the above-described method.

[0011] In a sixth aspect of this application, a chip includes a processor configured to invoke and run a computer program stored in a memory, thereby causing a device on which the chip is mounted to perform the methods described above.

[0012] In a seventh aspect of this application, a computer-readable storage medium stores a computer program that causes a computer to perform the above-described method.

[0013] In an eighth aspect of this application, a computer program product includes a computer program that causes a computer to perform the methods described above.

[0014] In a ninth aspect of this application, a computer program causes a computer to perform the above-described method. Attached Figure Description

[0015] To more clearly illustrate the embodiments or related technologies of this application, the accompanying drawings described in the embodiments are briefly introduced below. Obviously, the drawings are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without incurring any cost.

[0016] Figure 1 This is a communication block diagram of network nodes, service / source nodes, and / or one or more target nodes in a network system according to embodiments of this application.

[0017] Figure 2 This is a flowchart of a network handover enhancement method performed by a network system according to an embodiment of this application.

[0018] Figure 3 This is a flowchart of a network handover enhancement method performed by a network node according to an embodiment of this application.

[0019] Figure 4 This is a schematic diagram of a network-RAN architecture including transparent satellites according to an embodiment of this application.

[0020] Figure 5 This is a schematic diagram of a regenerable satellite without ISL and with gNB processing payload, according to an embodiment of this application.

[0021] Figure 6 This is a schematic diagram of a regenerable satellite with ISL and gNB processing payload, according to an embodiment of this application.

[0022] Figure 7 This is a schematic diagram of the NG-RAN architecture of a regenerative satellite based on gNB-DU, according to an embodiment of this application.

[0023] Figure 8A This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0024] Figure 8B This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0025] Figure 8C This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0026] Figure 9 This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0027] Figure 10 This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0028] Figure 11 This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0029] Figure 12 This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0030] Figure 13A This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0031] Figure 13B This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0032] Figure 14 This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0033] Figure 15 This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0034] Figure 16 This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0035] Figure 17 This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0036] Figure 18 This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0037] Figure 19 This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0038] Figure 20 This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0039] Figure 21 This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0040] Figure 22 This is a flowchart of a network handover enhancement method according to an embodiment of this application.

[0041] Figure 23 This is a block diagram of a wireless communication system according to an embodiment of this application. Detailed Implementation

[0042] The technical content, structural features, achieved objectives, and effects of this application are described in detail below with reference to the accompanying drawings. Specifically, the terminology used in the embodiments of this application is only used to describe the purpose of specific embodiments and is not intended to limit this application.

[0043] In some embodiments, the network refers to a node in an NTN system, including any of the following: space vehicles (such as satellites), air vehicles, and flying vehicles (such as drones); base stations; gateways; and the core network. An NTN system includes nodes such as satellites, gateways, base stations, and the core network. In some embodiments of this application, the network may refer to any node in an NTN system. "Satellite" can be further subdivided into various types, including space vehicles (such as satellites), air vehicles, and flying vehicles (such as drones).

[0044] Figure 1 This illustration depicts communication nodes in a network system 40 according to an embodiment of this application, including a network node 10, a serving / source node 20, and / or one or more target nodes 30. The network system 40 includes a network node 10, a serving / source node 20, and / or one or more target nodes 30. The network node 10 may include a memory 12, a transceiver 13, and a processor 11 connected to the memory 12 and the transceiver 13. The serving / source node 20 may include a memory 22, a transceiver 23, and a processor 21 connected to the memory 22 and the transceiver 23. One or more target nodes 30 may include a memory 32, a transceiver 33, and a processor 31 connected to the memory 32 and the transceiver 33. The processors 11, 21, or 31 may be configured to perform the functions, processes, and / or methods described in this specification. The various layers of the wireless interface protocol may be implemented in the processors 11, 21, or 31. Memory 12, 22, or 32 is operatively connected to processor 11, 21, or 31 and is used to store various information to drive the operation of processor 11, 21, or 31. Transceiver 13, 23, or 33 is operatively connected to processor 11, 21, or 31 and is responsible for transmitting and / or receiving wireless signals.

[0045] Processors 11, 21, or 31 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices. Memory 12, 22, or 32 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices. Transceivers 13, 23, or 33 may include baseband circuitry for processing radio frequency signals. When these implementations are implemented in software, the described functions can be performed by modules (such as programs, functions, etc.). These modules may be stored in memory 12, 22, or 32 and executed by processor 11, 21, or 31. Memory 12, 22, or 32 may be integrated inside processor 11, 21, or 31 or located outside the processor and communicatively connected to processor 11, 21, or 31 through various known methods. Furthermore, in some embodiments, processor 11 is configured to perform the following methods. In some embodiments, processor 21 is also configured to perform the following methods.

[0046] Figure 2 This is a flowchart of a network handover enhancement method 200 performed by a network system according to an embodiment of this application. In some embodiments, the network handover enhancement method 200 includes the following operation: operation 202, before the handover process begins, data is transmitted by a network node of the network system to a serving / source node and one or more target nodes.

[0047] Figure 3 This is a flowchart of a network handover enhancement method 300 performed by a network node according to an embodiment of this application. In some embodiments, the network handover enhancement method 300 includes the following operation: operation 302, before the handover process begins, the network node transmits data to the serving / source node and one or more target nodes.

[0048] Specifically, in some embodiments, network node 10 (e.g., core network CN or gateway GW) sends data to serving / source node 20 (e.g., source satellite SAT1 or source base station gNB1) and one or more target nodes (e.g., target satellites SAT2-N or target base stations gNB2-N) before the handover process begins. Source satellite SAT1 or source base station gNB1 performs the handover decision and sends handover signaling to user equipment (UE) to initiate the handover process. This method can reduce the signaling load during handover (e.g., NTN-NTN handover). No data forwarding is performed during and / or after the handover process.

[0049] In some embodiments, data is sent by network node 10 to serving / source node 20 and one or more target nodes 30 before the handover process begins, instead of being forwarded during and / or after the handover. That is, no data forwarding is required during and / or after the handover. In some embodiments, data may also be transmitted from one or more target nodes 30 to user equipment (UE) during and / or after the handover process is completed. Specifically, due to the predictability of satellite orbits, the target satellites serving the cell and subsequent target satellites can be predicted in advance. Therefore, network nodes (e.g., the core network CN) can transmit data (e.g., user data) not only to serving / source node 20 (e.g., the serving satellite) but also to one or more target nodes 30 (e.g., the target satellite and / or subsequent target satellites) before the handover process is initiated. In this case, no further data transmission from the source cell to the target cell is required during and / or after the handover, thereby reducing the data load during the handover process and further reducing the processing time of the handover process.

[0050] In some embodiments, the serving / source node 20 includes a serving / source satellite or a serving / source base station, while one or more target nodes 30 include one or more target satellites or one or more target base stations. In some embodiments, the network handover enhancement method is performed in a next-generation-radio access network (NG-RAN) architecture based on a non-terrestrial network (NTN). In some embodiments, the NTN-based NG-RAN architecture includes a transparent satellite-based NG-RAN architecture, a regenerative satellite-based NG-RAN architecture, and / or a multi-connectivity architecture involving NTN. In some embodiments, the regenerative satellite-based NG-RAN architecture includes a gNB processing payload, a gNB-DU processing payload, and / or a gNB processing payload based on a similar relay architecture.

[0051] Figure 4 This is a schematic diagram of a network-RAN architecture employing a transparent satellite, as shown in an embodiment of this application. The satellite (or unmanned aerial vehicle platform, UAS) can achieve a transparent payload. The satellite (or UAS platform) generates multiple beams within its service area of ​​field of view, and the coverage area of ​​the beams is elliptical. The field of view of the satellite (or UAS platform) depends on its onboard antenna pattern and minimum elevation angle. A transparent payload refers to a payload that possesses RF filtering, frequency conversion, and signal amplification functions, so that the waveform signal repeated by the payload remains unchanged. Figure 4As shown, the satellite payload performs frequency conversion and RF amplifier functions in both uplink and downlink directions, corresponding to an analog RF repeater. Therefore, the satellite will repeat the NR-Uu radio interface signal between the feed link (between the NTN gateway and the satellite) and the service link (between the satellite and the user equipment (UE), and vice versa. The satellite radio interface (SRI) on the feed link is NR-Uu. In other words, the satellite does not terminate the NR-Uu interface; the NTN gateway (GW) supports all necessary functions to forward the NR-Uu interface signal. Different transparent satellites can connect to the same gNB on the ground.

[0052] If the serving / source node includes a serving / source base station, and one or more target nodes include one or more target base stations, then the network handover enhancement method will be executed in the transparent satellite-based NG-RAN architecture.

[0053] For a network-RAN architecture using transparent satellites, since the gNBs are deployed on the ground, data is forwarded from the source gNB to the target gNB, and both gNBs are located on the ground. However, due to the high-speed movement of satellites, the NTN handover process may require strict latency control. Therefore, the uplink latency caused by data forwarding during the handover process may become a problem and needs to be optimized.

[0054] For a network-RAN architecture using transparent satellites, during downlink transmission, the core network (CN) can simultaneously send data (such as user data) to the serving gNB, the target gNB, and / or subsequent target gNBs before the handover process. No data forwarding is required during and / or after the handover. The target gNB can send user data to the UE during and / or after the handover is complete. The advantages of this approach include reduced data load between inter-satellite links (ISLs) and reduced handover processing time. This approach is primarily suitable for inter-gNB handover scenarios (inter-gNB HO).

[0055] Figure 5This is a schematic diagram of a regenerative satellite without inter-satellite links (ISL) and equipped with gNB processing payloads, according to an embodiment of this application. This satellite (or unmanned aerial vehicle platform, UAS) can implement regenerative payloads. The satellite (or UAS platform) generates multiple beams within its service area of ​​field of view, and the coverage area of ​​these beams is elliptical. The field of view of the satellite (or UAS platform) depends on the radiation pattern of the onboard antenna and the minimum elevation angle. A regenerative payload refers to a payload that possesses functions such as radio frequency filtering, frequency conversion, signal amplification, demodulation / decoding, switching and / or routing, and encoding / modulation. In effect, it integrates all or part of the functions of a base station (e.g., gNB) onto the satellite (or UAS platform). For constellation satellite systems, inter-satellite links (ISL) can also be optionally added, in which case the satellite must have regenerative payload capabilities.

[0056] When the serving / source node is a serving / source satellite and one or more target nodes are one or more target satellites, the network handover enhancement method can be implemented in a regenerative satellite NG-RAN architecture that has gNB processing payload but no inter-satellite link (ISL).

[0057] For regenerated satellites without an ISL but equipped with gNB processing payloads, the data forwarding path from the source satellite to the target satellite may be as follows due to the lack of an ISL: data (e.g., user data) is forwarded from the source satellite to the source gateway (G), then to the source gNB, then to the core network (CN), then to the target gNB, the target gateway, and finally to the target satellite. This process can place a significant load on all interfaces, including the feeder link, the satellite radio interface (SRI), and the NG interface.

[0058] In downlink transmission, the core network can send user data to the serving satellite, target satellite, and / or subsequent target satellites before the handover process begins, eliminating the need for data forwarding during and / or after the handover. The target satellite can send user data to the user equipment during and / or after the handover process. Because satellite orbits are predictable, the target satellite and subsequent target satellites that may serve the cell can be predicted. Therefore, the core network can simultaneously send user data to the serving satellite, target satellite, and / or subsequent target satellites before the handover process is initiated. In this case, data transmission from the source cell to the target cell is no longer required during and / or after the handover.

[0059] Figure 6This is a schematic diagram of a regenerative satellite equipped with an ISL (Integrated Signalling Link) and a gNB (Ground-Only Node) processing payload, according to an embodiment of this application. In a satellite constellation system, an ISL can be selectively configured, which may require the satellite to be equipped with a regenerative payload. The ISL can operate in the radio frequency band or the optical band. The satellite payload also provides an ISL between satellites. The ISL is a transmission link between satellites and can be a wireless interface or an optical interface. The NTN gateway is a transmission network layer node that supports all necessary transmission protocols. Figure 6 This illustrates a scenario where a UE, served by a gNB on a satellite, can access the 5G core network (5GCN) on the ground via an ISL. gNBs deployed on different satellites can connect to the same terrestrial 5GCN. If multiple gNBs are mounted on a single satellite, the same SRI can carry all corresponding NG interface instances.

[0060] When the serving / source node is a serving / source satellite and one or more target nodes are one or more target satellites, the network handover enhancement method can be implemented in a regenerative satellite NG-RAN architecture with gNB processing payload and ISL.

[0061] For regenerable satellites equipped with ISL and gNB processing payloads, data can be directly relayed from the source satellite to the target satellite via ISL. Besides latency issues, this can also significantly increase the data load on the ISL.

[0062] In downlink transmission, the core network can send data (such as user data) to the serving satellite, target satellite, and / or subsequent target satellites before the handover process begins, eliminating the need for data forwarding during and / or after the handover. The target satellite can send user data to the user equipment during and / or after the handover process. Because satellite orbits are predictable, the target satellites and subsequent target satellites serving the cell can be predicted in advance. Therefore, the core network (CN) can send user data not only to the serving satellite but also to the target satellite and / or subsequent target satellites before the handover process begins. In this case, data transmission from the source cell to the target cell is unnecessary during and / or after the handover.

[0063] Figure 7This is a schematic diagram of the NG-RAN architecture for a regenerable satellite based on a gNB-DU, according to an embodiment of this application. The NG-RAN logical architecture with CU / DU separation serves as the basis for the NTN scenario. The satellite payload enables the regeneration of signals from the ground. The NR-Uu radio interface on the serving link exists between the satellite and the user equipment. The SRI on the feed link exists between the NTN gateway and the satellite, and the SRI carries the F1 protocol. The satellite payload provides ISL between satellites. The SRI is a transport link, and its logical interface F1 is a 3GPP-defined interface. The NTN gateway is a transport network layer node that supports all necessary transport protocols. DUs deployed on different satellites can connect to the same CU on the ground. If a satellite carries multiple DUs, the SRI can carry all corresponding F1 interface instances.

[0064] When the serving / source node is a serving / source base station and one or more target nodes are one or more target base stations, the network handover enhancement method can be implemented in a regenerative satellite NG-RAN architecture with gNB-DU processing payload.

[0065] For the gNB-DU-based regenerative satellite NG-RAN, since the PDCP function is located on the ground, the data forwarding process in this architecture is the same as or similar to the transparent satellite network-RAN architecture described above.

[0066] For regenerative satellite NG-RAN based on gNB-DU, during downlink transmission, the core network can send data (such as user data) to the serving gNB, target gNB, and / or subsequent target gNB before the handover process begins, eliminating the need for data forwarding during and / or after the handover. The target gNB can transmit user data to the UE during and / or after the handover. The advantage of this approach is that it reduces the data load between ISLs and decreases the handover processing time during the handover process.

[0067] The differences between the network-RAN architecture based on transparent satellites and the NG-RAN architecture based on gNB-DU regenerative satellites, and between the solutions for gNB-based payload regenerative satellites with and without ISL, include at least one of the following aspects. This solution primarily targets inter-gNB handover (inter-gNB HO) scenarios.

[0068] In existing technologies, if a conventional handover (Legacy HO) method is used, data forwarding may occur between satellites, depending on whether an ISL (Independent Switching Level) is present or absent (a common configuration for regenerative satellites). However, in some embodiments, by employing the regenerative satellite scheme described in this application, which has a gNB processing payload but lacks an ISL, data forwarding between satellites can be eliminated. For conventional handover or the Network-RAN architecture based on transparent satellites and the NG-RAN architecture based on gNB-DU proposed in this application, data forwarding may occur on the ground.

[0069] The advantages of the regenerative satellite scheme with gNB processing payload and with or without ISL as described in this application include: reduced data load during handover and further shortened handover processing time. The advantages of the network-RAN architecture based on transparent satellites and the NG-RAN architecture based on gNB-DU regenerative satellites are: reduced data load between ISLs during handover and further shortened handover processing time.

[0070] In some embodiments, the core network may transmit data (such as user data) to multiple target satellites before the handover process begins. The number of target satellites can be specified or determined by the network implementation. Specifically, the core network sends user data to several target satellites before the handover process, the number of which is pre-set or determined based on the network deployment.

[0071] In some embodiments, the switching process may include normal switching or conditional switching. Specifically, in some examples, normal switching may be a traditional normal switching; in some examples, conditional switching may be a traditional conditional switching.

[0072] In some embodiments, the network node transmits data to the serving / source node and one or more target nodes before the handover process begins, further including:

[0073] Before making a switching decision, network nodes transmit data to the service / source node and one or more target nodes.

[0074] After the handover preparation is completed but before the handover decision is made, the network node transmits data to the service / source node and one or more target nodes.

[0075] Alternatively, the network node may transmit data to the service / source node and one or more target nodes after the service / source node sends an instruction to the network node, and after the handover preparation but before the handover decision.

[0076] In some embodiments, network nodes include a core network (CN) or a gateway (GW). Since different satellites can connect to the same GW, the CN can first send data to the GW, which then stores and transmits the user data to the target satellite, further reducing processing time. Therefore, there are two options (CN or GW) for performing the transmission of user data to the target satellite. In some examples, the gateway (GW) is particularly suitable for scenarios where multiple satellites connect to the same GW. This embodiment, for example, applies to a regenerative satellite NG-RAN architecture that processes payloads based on gNBs, including regenerative satellites with or without inter-satellite links (ISL).

[0077] In some embodiments, the network handover enhancement method further includes determining whether a packet state is transmitted from a serving / source node to one or more target nodes. The packet state may refer to the sending and / or receiving status of packets. Specifically, for example, the packet state indicates which packets can be correctly received and which packets are lost. More specifically, in some examples, the packet state includes the sequence number (SN) status of the Packet Data Convergence Protocol (PDCP).

[0078] In some examples, if it is necessary to transmit the PDCP SN status from the source satellite to the target satellite, the target satellite can determine which PDCP protocol data unit (PDU) needs to be transmitted to the UE next based on the received PDCP status report.

[0079] In some examples, if it is not necessary to transmit the PDCP SN status from the source satellite to the target satellite, the target satellite can transmit the next data packet without a PDCP status report, for example, the decision is made by the network side. At the same time, the UE can perform duplicate detection and discard operations on its own, for example, the decision is made by the UE.

[0080] For solutions involving gNBs with ISL-enabled payload regeneration satellites and gNBs without ISL-enabled payload regeneration satellites, please refer to the following Examples 1 to 24. Furthermore, for solutions based on transparent satellite network-RAN architectures and gNB-DU-based regeneration satellite NG-RAN architectures, please refer to the following Examples 1 to 24, provided that the entity is replaced by a gNB.

[0081] Example 1:

[0082] Figure 8A , Figure 8B and Figure 8CIn some embodiments, the handover process includes a normal handover, where data is transmitted from a network node to a serving / source node and one or more target nodes prior to the handover decision. The network node is the core network (CN), and the packet status is transmitted from the serving / source node to one or more target nodes.

[0083] Source satellite SAT1 (abbreviated as SAT1): The satellite serving the current cell. Target satellite SAT2 (abbreviated as SAT2): The satellite serving the next cell. Target satellites SAT3~N (abbreviated as SAT3~N): The satellites serving the next cell after SAT2.

[0084] Figure 8A , Figure 8B and Figure 8C In some embodiments, the CN transmits data (such as user data) to SAT1-N. The source satellite SAT1 performs the handover decision and sends handover signaling to the UE to initiate the handover process. The PDCP CN state can be transmitted from SAT1 to SAT2 during and / or after the handover. The CN transmits data to SAT2-N during and / or after the handover process is complete. SAT2 begins providing service to the UE in the cell. This method reduces the signaling burden during handover processes (such as NTN-to-NTN handover). No data forwarding is required during and / or after the handover.

[0085] Figure 8A , Figure 8B and Figure 8C In some examples, it is shown that in the general operation flow, network nodes (such as CN) transmit data to SAT2 and / or SAT3~N after the handover is completed (i.e., the handover process is completed). Figure 8A In some examples, SAT2 transmits data to the UE after the handover is complete; Figure 8B In some examples, SAT2 transmits data to the UE during the handover completion process; Figure 8C In some examples, SAT2 transmits data to the UE during and after the handover is completed. Figures 9 to 22 The subsequent embodiments are applicable to or similar to Figure 8A , Figure 8B and Figure 8C Examples. That is, in some examples, during general operation, the network node (such as CN or GW) transmits data to the target node (such as gNB2 or SAT2) and / or the target node group (such as gNB3~N or SAT3~N) after handover is complete. In some examples, the target node (such as gNB2 or SAT2) transmits data to the UE during and / or after handover is complete. Therefore, the following Figures 9 to 22 They will no longer be drawn and described one by one.

[0086] Figures 8A to 11 The switching (HO) decision-making methods in some embodiments are shown. Figure 8A , Figure 8B and Figure 8C In some embodiments, the network system includes a UE, a source satellite SAT1, a core network CN, a target satellite SAT2, and target satellites SAT3 to N, wherein the handover decision is performed by the source satellite SAT1. Figure 9 In some embodiments, the network system includes a UE, source satellite SAT1, CN, target satellite SAT2, and target satellites SAT3-N, wherein the UE performs conditional handover (CHO) decisions. Figure 10 In some embodiments, the network system includes a UE, a source satellite SAT1, a CN, a gateway GW, a target satellite SAT2, and target satellites SAT3 to N, wherein the handover decision is performed by the source satellite SAT1. Figure 11 In some embodiments, the network system includes a UE, source satellite SAT1, CN, GW, target satellite SAT2, and target satellites SAT3 to N, wherein the handover decision is performed by the UE.

[0087] Example 2:

[0088] The handover process is a normal handover. Data is transmitted from network nodes to the serving / source node and one or more target nodes before the handover decision is made. The network nodes are the core network (CN), and the serving / source node does not transmit any packet status information to the target nodes. This scheme can reduce the signaling load generated during handovers such as from NTN to NTN. No data forwarding is required during and / or after the handover.

[0089] There is no need to transmit the PDCP SN status report from the source satellite to the target satellite. In this case, the target satellite can send the next data packet directly without relying on the PDCP status report, which can be handled by the network side; and the UE can perform duplicate data detection and discarding itself, which can be implemented by the UE itself. All other steps or operations are the same as or similar to those in the above embodiments (such as Embodiment 1).

[0090] Example 3:

[0091] Figures 8A to 11 The switching (HO) decision-making method in some embodiments is shown. Figure 8A , Figure 8B and Figure 8C In some embodiments, the network system includes a UE, a source satellite SAT1, a core network CN, a target satellite SAT2, and target satellites SAT3 to N, wherein the handover decision is performed by the source satellite SAT1. Figure 9In some embodiments, the network system includes a UE, source satellite SAT1, CN, target satellite SAT2, and target satellites SAT3-N, wherein the UE performs conditional handover (CHO) decisions. Figure 10 In some embodiments, the network system includes a UE, a source satellite SAT1, a CN, a gateway GW, a target satellite SAT2, and target satellites SAT3 to N, wherein the handover decision is performed by the source satellite SAT1. Figure 11 In some embodiments, the network system includes a UE, source satellite SAT1, CN, GW, target satellite SAT2, and target satellites SAT3 to N, wherein the handover decision is performed by the UE.

[0092] Example 2:

[0093] The handover process is a normal handover. Data is transmitted from network nodes to the serving / source node and one or more target nodes before the handover decision is made. The network nodes are the core network (CN), and the serving / source node does not transmit any packet status information to the target nodes. This scheme can effectively reduce signaling load during handovers such as from NTN to NTN. No data forwarding is required during and / or after the handover.

[0094] There is no need to transmit the PDCP sequence number (SN) status report from the source satellite to the target satellite. In this case, the target satellite can transmit the next data packet without the PDCP status report, which can be implemented by the network side; while the UE can perform duplicate data detection and discarding itself, which can be implemented by the UE side. All other steps or operations are the same as or similar to those in the aforementioned embodiments (such as Embodiment 1).

[0095] Example 3:

[0096] Figure 12 In some embodiments, the handover process is a normal handover, where data is transmitted from the network node to the serving / source node and one or more target nodes before the handover decision and after handover preparation. The network node is the core network (CN), and the packet status is transmitted from the serving / source node to one or more target nodes. This scheme can effectively reduce signaling load during handovers such as from NTN to NTN. No data forwarding is required during and / or after the handover.

[0097] The difference between Example 3 and Example 1 is that the time point for data transmission is specified. This time point is after the handover preparation is completed. Figure 12 The following diagram illustrates the stages of a conventional normal handover in some embodiments, with the boxed portion representing the handover preparation stage. All other steps or operations are the same as or similar to those in the foregoing embodiments.

[0098] Example 4:

[0099] The handover process is a normal handover. Data is transmitted from the network node to the serving / source node and one or more target nodes before the handover decision and after the handover preparation. The network node is the core network (CN), and the serving / source node does not transmit any packet status information to the one or more target nodes. This scheme can effectively reduce signaling load during handovers such as from NTN to NTN. No data forwarding is required during and / or after the handover.

[0100] There is no need to transmit the PDCP sequence number (SN) status report from the source satellite to the target satellite. In this case, the target satellite can transmit the next data packet without the PDCP status report, which can be handled by the network side; and the UE can perform duplicate data detection and discarding itself, which can be implemented by the UE itself. All other steps or operations are the same as or similar to those in the aforementioned embodiments.

[0101] Example 5:

[0102] Figure 13A In some embodiments, the handover process is a normal handover, where data is transmitted by the network node to the serving / source node and one or more target nodes before the handover decision, after handover preparation, and after the serving / source node sends an instruction to the network node. The network node is the core network (CN), and packet status is transmitted by the serving / source node to one or more target nodes. This scheme can effectively reduce signaling load during handovers such as from NTN to NTN. No data forwarding is required during and / or after the handover.

[0103] The difference between Example 5 and Examples 1 and 2 is that data transmission occurs after the handover preparation is complete, and data transmission only begins after the source satellite sends an instruction to the CN. All other steps or operations are the same as or similar to those in the above examples.

[0104] More specifically, Figure 13B A detailed example of the switching process is shown below.

[0105] The relevant steps or operations include the following:

[0106] 0. The UE context in the source gNB contains information about roaming and access restrictions, which is provided when the connection is established or at the time of the last TA update.

[0107] 1. The source gNB configures the UE's measurement process and receives reports from the UE based on the measurement configuration.

[0108] 2. The source gNB determines whether to perform a handover to the UE based on the Measurement Report and Radio Resource Management (RRM) information.

[0109] 3. The source gNB sends a Handover Request message to the target gNB, containing a transparent RRC container that includes the information needed to prepare for handover on the target side. This information includes at least the target cell ID, KgNB*, UE's C-RNTI in the source gNB, RRM configuration (including UE inactivity time), basic access stratum (AS) configuration (including antenna information and downlink carrier frequency), QoS flow to DRB mapping rules applied to the UE, source gNB's SIB1, UE's capability information for different RATs, PDU session-related information, and may include measurement information reported by the UE (including beam-related information, if any). PDU session-related information includes slice information and QoS profiles at the QoS flow level. The source gNB may also request DAPS handover to one or more DRBs.

[0110] Note 1: Once the source gNB issues a handover request, the UE should not be reconfigured, including performing the mapping operation of reflective QoS flow to DRB.

[0111] The target gNB can perform admission control. If slice information is sent, slice-aware admission control must be performed. If a PDU session is associated with a slice that the target gNB does not support, the target gNB should reject those PDU sessions.

[0112] The target gNB prepares for handover using L1 / L2 layers and sends a handover request confirmation (HANDOVER REQUESTACKNOWLEDGE) to the source gNB, which contains a transparent container that will be passed to the UE as an RRC message to perform the handover. The target gNB also indicates whether it accepts the DAPS handover.

[0113] Note 2: Data forwarding can be initiated once the source gNB receives confirmation of the handover request, or once the downlink handover command begins transmission.

[0114] Note 3: For DRBs configured with DAPS, the source gNB will continue to use its allocated SN to forward downlink PDCP SDUs for regular data forwarding before transferring the SN allocation right to the target gNB in ​​step 8b.

[0115] Added step 1a: The source satellite / gNB sends an instruction to the AMF regarding data delivery from the UPF to the target satellite / gNB (via NGAP message), and the AMF then transmits the instruction to the UPF.

[0116] Added step 1b: The source satellite / gNB sends an instruction to the UPF, informing it of the method for transmitting data from the UPF to the target satellite / gNB.

[0117] Added step 2: UPF transmits user data to the target satellite / gNB.

[0118] 6. The source gNB triggers a Uu interface handover by sending an RRC Reconfiguration message to the UE. This message contains information required to access the target cell: at least the target cell ID, the new C-RNTI, and the identifier of the security algorithm selected by the target gNB. It may also include a set of dedicated RACH resources, the mapping between RACH resources and SSBs, the mapping between RACH resources and UE-specific CSI-RS configurations, public RACH resources, and system information of the target cell.

[0119] Note 4: For DRBs configured with DAPS, the source gNB will not stop transmitting downlink data packets until it receives a HANDOVER SUCCESS message from the target gNB.

[0120] Note 4a: CHO (Conditional Toggle) cannot be configured simultaneously with DAPS toggle.

[0121] 7a. For a DRB configured with DAPS, the source gNB sends an EARLY STATUS TRANSFER message. The DL COUNT value contained in this message indicates the PDCP SN and HFN of the first PDCP SDU forwarded by the source gNB to the target gNB. The source gNB does not stop allocating SNs for downlink PDCP SDUs until it sends an SN STATUS TRANSFER message to the target gNB in ​​step 8b.

[0122] 7. For a DRB without DAPS configured, the source gNB sends an SN STATUS TRANSFER message to the target gNB to transmit the uplink PDCP SN receive status and downlink PDCP SN transmit status (i.e., for RLCAM) of the DRB that needs to retain PDCP status. The uplink PDCP SN receive status includes at least the PDCP SN of the first missing uplink PDCP SDU and may include a bitmap of the receive status of out-of-order uplink PDCP SDUs that the UE needs to retransmit in the target cell (if any). The downlink PDCP SN transmit status indicates the next PDCP SN that the target gNB should allocate for a new PDCP SDU that has not yet been allocated a SN.

[0123] Note 5: In the case of DAPS handover, for DRBs using RLC-AM and not configured with DAPS, their uplink PDCP SN receive status and downlink PDCP SN transmit status can be transmitted via the SN STATUS TRANSFER message in step 8b, instead of in step 7.

[0124] Note 6: For DRBs configured with DAPS, the source gNB can also send an EARLY STATUS TRANSFER message between steps 7 and 8b to inform that forwarded PDCP SDUs have been discarded. The target gNB will not send forwarded downlink PDCP SDUs with a PDCP COUNT less than the DL COUNT value shown in the EARLYSTATUS TRANSFER to the UE; if these SDUs have not yet been attempted to be transmitted, they will be discarded.

[0125] 8. The UE synchronizes with the target cell and completes the RRC handover process by sending an RRCReconfigurationComplete message to the target gNB. If it is a DAPS handover, the UE will not immediately disconnect from the source cell after receiving the RRCReconfiguration message. Only after receiving an explicit release message from the target node will the UE release the source-side resources and configuration, and cease downlink / uplink reception / transmission with the source gNB.

[0126] Note 6a: From the perspective of the Radio Access Network (RAN), a DAPS handover is considered complete only after the UE releases the source cell according to the explicit request of the target node. RRC suspend, subsequent handover, or inter-RAT handover cannot be initiated before the source cell is released.

[0127] Note 7: For DRBs configured with DAPS, if RLC-UM is used, the uplink PDCP SN receive status and downlink PDCP SN transmit status will also be transmitted in the SN STATUS TRANSFER message in step 8b.

[0128] Note 8: For DRBs configured with DAPS, the source gNB will not stop transmitting uplink QoS flows to the UPF before sending the SN STATUS TRANSFER message in step 8b. The target gNB will not forward QoS flows of its received uplink PDCP SDUs to the UPF until it receives the SN STATUS TRANSFER message. The uplink HFN and the first missing uplink PDCP SN in this message identify the starting point of the uplink PDCP SDUs to be delivered to the UPF. The target gNB will not transmit any uplink PDCP SDUs with a UL COUNT lower than this indication value.

[0129] Note 9: Invalid.

[0130] 9. The target gNB sends a PATH SWITCH REQUEST message to the AMF to trigger the 5GC to switch the downlink data path to the target gNB and establish an NG-C interface instance to the target gNB.

[0131] 10.5GC switches the downlink data path to the target gNB. The UPF sends one or more "end marker" packets to the source gNB (per PDU session / tunnel), and then releases any user plane (U-plane) / transport network layer (TNL) resources pointing to the source gNB.

[0132] 11. AMF acknowledges the PATH SWITCH REQUEST message via the PATH SWITCH REQUEST ACKNOWLEDGE message.

[0133] The RRM (Radio Resource Management) configuration can include beam measurement information (for Layer 3 mobility) of the SSB and CSI-RS associated with the reported cell, if both types of measurement information are available. Additionally, if carrier aggregation (CA) is configured, the RRM configuration can include a list of the best cells for which measurement information is obtained on each frequency band. The RRM measurement information can also include beam measurement data for the listed cells belonging to the target gNB.

[0134] The general RACH configuration for beams in the target cell is associated only with the SSB. The network can configure dedicated RACHs for the SSB and / or CSI-RS within a cell. The target gNB can only include one of the following RACH configurations in its handover command to enable the UE to access the target cell:

[0135] i) General RACH configuration.

[0136] ii) General RACH configuration + dedicated RACH configuration associated with SSB.

[0137] iii) General RACH configuration + dedicated RACH configuration associated with CSI-RS.

[0138] A dedicated RACH configuration allocates one or more RACH resources, along with a quality threshold for their use. When dedicated RACH resources are available, the UE prioritizes using them, and will not switch to contention-based RACH resources as long as the dedicated resources meet the quality threshold. The order in which dedicated RACH resources are accessed is determined by the specific UE implementation.

[0139] When a UE receives a handover command requesting a DAPS handover, it suspends the source cell's SRB, stops sending and receiving any RRC control plane signaling to and from the source cell, and establishes the target cell's SRB. After a successful DAPS handover, the UE releases the source cell's SRB configuration upon receiving a source cell release indication from the target cell. If the DAPS handover to the target cell fails, and the source cell link remains available, the UE rolls back to the source cell configuration and restores the source cell's SRB to continue control plane signaling transmission.

[0140] Example 6:

[0141] The handover process includes a normal handover, where data is transmitted from the network node to the serving / source node and one or more target nodes before the handover decision, after handover preparation is complete, and after the serving / source node sends an instruction to the network node. The network node contains the core network (CN) and does not transmit any packet status information from the serving / source node to the one or more target nodes. This can reduce signaling overhead during handovers such as non-terrestrial network to non-terrestrial network (NTN-NTN). There is no data forwarding during and / or after the handover.

[0142] There is no need to transmit the PDCP SN status report from the source satellite to the target satellite. In this case, the target satellite will transmit the next data packet without a PDCP status report, for example, the decision can be left to the network implementation; the UE can perform duplicate detection and discarding itself, for example, the decision can be left to the UE implementation. Other steps or operations are the same as or similar to those in the foregoing embodiments.

[0143] Example 7:

[0144] Figure 14In some embodiments, the handover process is illustrated as a conditional handover (CHO), where data is transmitted from the network node to the serving / source node and one or more target nodes prior to the handover decision. The network node contains the core network (CN) and transmits packet status from the serving / source node to one or more target nodes. This can reduce signaling overhead during handover processes such as NTN-NTN. There is no data forwarding during and / or after the handover. The difference from Embodiment 1 is that this is a conditional handover procedure. Other steps or operations are the same as or similar to those in the foregoing embodiments.

[0145] Example 8:

[0146] The handover process includes conditional handover, where data is transmitted from the network node to the serving / source node and one or more destination nodes before the handover decision. The network node includes the core network (CN), and no packet status information is transmitted from the serving / source node to the one or more destination nodes. This can reduce signaling overhead during handovers such as from a non-terrestrial network to a non-terrestrial network (NTN-NTN). There is no data forwarding during and / or after the handover.

[0147] There is no need to transmit the PDCP SN status report from the source satellite to the target satellite. In this case, the target satellite will send the next data packet without a PDCP status report, which may be determined by the network implementation; the UE can perform duplicate detection and discarding itself, which may be determined by the UE. Other steps or operations are the same as or similar to those in the foregoing embodiments.

[0148] Example 9:

[0149] Figure 15 In some embodiments, the handover process includes conditional handover, where data is transmitted from network nodes to serving / source nodes and one or more target nodes before the handover decision and after handover preparation is complete. The network nodes include the core network (CN), and packet status information is transmitted from the serving / source node to one or more target nodes. This can reduce signaling overhead during handovers such as NTN-NTN. No data forwarding occurs during and / or after the handover. This embodiment differs from Embodiment 4 in that the data transmission time is specified, i.e., it occurs immediately after handover preparation is complete. Other steps or operations are the same as or similar to those in the embodiments described above.

[0150] Example 10:

[0151] The handover process includes conditional handover, where data is transmitted from network nodes to serving / source nodes and one or more target nodes before the handover decision is made and after handover preparation is complete. The network nodes include the core network (CN), and no packet status information is transmitted from the serving / source nodes to the one or more target nodes. This can reduce signaling overhead during handovers such as NTN-NTN. There is no data forwarding during and / or after the handover.

[0152] There is no need to transmit the PDCP SN status report from the source satellite to the target satellite. In this case, the target satellite will send the next data packet without a PDCP status report, which may be determined by the network implementation; the UE can perform duplicate detection and discarding itself, which may be determined by the UE. Other steps or operations are the same as or similar to those in the foregoing embodiments.

[0153] Example 11:

[0154] Figure 16 In some embodiments, the handover process includes conditional handover, where data is transmitted from the network node to the serving / source node and one or more target nodes before the handover decision, after handover preparation is complete, and after the serving / source node sends an instruction to the network node. The network node includes the core network (CN) and transmits packet status information from the serving / source node to one or more target nodes. This can reduce signaling overhead during handover processes such as NTN-NTN. There is no data forwarding during and / or after the handover. This embodiment differs from embodiments 4 and 5 in that the data transmission occurs after handover preparation is complete and waits for the source satellite to send an instruction to the core network. Other steps or operations are the same as or similar to those in the aforementioned embodiments.

[0155] Example 12:

[0156] The handover process includes conditional handover, where data is transmitted from the network node to the serving / source node and one or more target nodes before the handover decision, after handover preparation is complete, and after the serving / source node sends an instruction to the network node. The network node includes the core network (CN), and no packet status information is transmitted from the serving / source node to the one or more target nodes. This can reduce signaling overhead during handovers, such as from a non-terrestrial network to a non-terrestrial network (NTN-NTN). There is no data forwarding during and / or after the handover.

[0157] There is no need to transmit the PDCP SN status report from the source satellite to the target satellite. In this case, the target satellite will send the next data packet without a PDCP status report, which may be determined by the network implementation; the UE can perform duplicate detection and discarding itself, which may be determined by the UE. Other steps or operations are the same as or similar to those in the foregoing embodiments.

[0158] Example 13:

[0159] Figure 17 In some embodiments, the handover process includes a normal handover, where data is transmitted from network nodes to serving / source nodes and one or more target nodes prior to the handover decision. The network nodes include gateways and transmit packet status information from the serving / source nodes to one or more target nodes. This can reduce signaling overhead during handovers such as NTN-NTN handovers. No data forwarding occurs during and / or after the handover.

[0160] The difference between this embodiment and Embodiment 1 is that, in the scenario where the feeder link remains unchanged, the core network (CN) can first transmit the data to the gateway, and the gateway can store the data and then send it to the target satellite. This approach can further reduce signaling burden and handover latency.

[0161] Source satellite SAT1: The satellite of the current serving cell. Target satellite SAT2: The satellite of the next serving cell. Target satellites 3 to N: The satellites of the next serving cell after SAT2.

[0162] Figure 17 As shown, in some embodiments, the process can proceed as follows: the core network (CN) transmits data to the gateway (GW); the GW sends the data to SAT1–N; the source satellite SAT1 performs a handover decision and sends handover signaling to the UE to initiate the handover process. The PDCP CN state can be transmitted from SAT1 to SAT2 during and / or after the handover. The GW sends data to SAT2–N during and / or after the handover. SAT2 then begins providing services to the UEs within the cell.

[0163] Example 14:

[0164] The handover process includes a normal handover, in which data is transmitted from network nodes to the serving / source node and one or more destination nodes before the handover decision. The network nodes include gateways (GWs), and no packet status information is transmitted from the serving / source node to the one or more destination nodes. This can reduce signaling overhead during handovers such as NTN-NTN handovers. There is no data forwarding during and / or after the handover.

[0165] There is no need to transmit the PDCP SN status report from the source satellite to the target satellite. In this case, the target satellite will send the next data packet without a PDCP status report, which may be determined by the network implementation; the UE can perform duplicate detection and discarding itself, which may be determined by the UE. Other steps or operations are the same as or similar to those in the foregoing embodiments.

[0166] Example 15:

[0167] Figure 18 As shown, in some embodiments, the handover process includes a normal handover. Before the handover decision and after handover preparation is complete, data is transmitted from network nodes to serving / source nodes and one or more target nodes. The network nodes include gateways (GWs), and packet status is transmitted from the serving / source node to one or more target nodes. This can reduce signaling load during handovers such as NTN-NTN. No data forwarding occurs during and / or after the handover. This embodiment differs from Embodiment 7 in that the timing of data transmission is specifically specified. This timing is after handover preparation is complete. Other steps or operations are the same as or similar to those in the above embodiments.

[0168] Example 16:

[0169] The handover process includes a normal handover. Before the handover decision and after handover preparation is complete, data is transmitted from network nodes to the serving / source node and one or more target nodes. The network nodes include gateways (GWs), and no packet status information is transmitted from the serving / source node to one or more target nodes. This can reduce signaling overhead during handovers such as NTN-NTN handovers. There is no data forwarding during and / or after the handover.

[0170] There is no need to transmit the PDCP SN status report from the source satellite to the target satellite. In this case, the target satellite sends the next data packet without a PDCP status report, which can be determined by the network; the UE can perform duplicate detection and discarding itself, which can also be determined by the UE. Other steps or operations are the same as or similar to those in the above embodiments.

[0171] Example 17:

[0172] Figure 19 As shown, in some embodiments, the handover process includes a normal handover. Data is transmitted from the network node to the serving / source node and one or more target nodes before the handover decision, after handover preparation is complete, and after the serving / source node sends an instruction to the network node. The network nodes include gateways (GWs), and packet status is transmitted from the serving / source node to one or more target nodes. This can reduce signaling load during handovers, such as non-terrestrial network to non-terrestrial network (NTN-NTN). There is no data forwarding during and / or after the handover. This embodiment differs from embodiments 7 and 8 in that data transmission occurs after handover preparation is complete and after waiting for the source satellite to send an instruction to the core network (CN). Other steps or operations are the same as or similar to those in the above embodiments.

[0173] Example 18:

[0174] The handover process includes a normal handover. Before the handover decision, after handover preparation is complete, and after the serving / source node sends an instruction to the network node, data is transmitted from the network node to the serving / source node and one or more target nodes. The network nodes include gateways (GWs) and do not transmit any packet status information from the serving / source node to the one or more target nodes. This can reduce signaling load during handovers such as NTN-NTN handovers.

[0175] There is no need to transmit the PDCP SN status report from the source satellite to the target satellite. In this case, the target satellite will send the next data packet without a PDCP status report, which may be determined by the network implementation; the UE can perform duplicate detection and discarding itself, which may be determined by the UE. There is no data forwarding during and / or after the handover. Other steps or operations are the same as or similar to those in the above embodiments.

[0176] Example 19:

[0177] Figure 20 As shown, in some embodiments, the handover process includes conditional handover (CHO). Prior to the handover decision, data is transmitted from network nodes to serving / source nodes and one or more target nodes. The network nodes include gateways (GWs), and packet states are transmitted from serving / source nodes to one or more target nodes. This can reduce signaling load during handovers, such as between non-terrestrial networks (NTN-NTN). No data forwarding occurs during and / or after the handover. This embodiment differs from Embodiment 7 in that this embodiment uses a conditional handover process. Other steps or operations are the same as or similar to those in the above embodiments.

[0178] Example 20:

[0179] The handover process includes conditional handover. Before the handover decision, data is transmitted from network nodes to the serving / source node and one or more target nodes. These network nodes include gateways (GWs), and no packet status information is transmitted from the serving / source node to the one or more target nodes. This can reduce signaling load during handovers such as NTN-NTN. There is no data forwarding during and / or after the handover.

[0180] There is no need to transmit the PDCP SN status report from the source satellite to the target satellite. In this case, the target satellite will send the next data packet without a PDCP status report, which may be determined by the network implementation; the UE can perform duplicate detection and discarding itself, which may be determined by the UE. Other steps or operations are the same as or similar to those in the above embodiments.

[0181] Example 21:

[0182] Figure 21As shown, in some embodiments, the handover process includes a conditional handover (CHO). Before the handover decision and after handover preparation, data is transmitted from network nodes to serving / source nodes and one or more target nodes. The network nodes include gateways (GWs), and packet states are transmitted from serving / source nodes to one or more target nodes. This can reduce signaling load during handovers, such as non-terrestrial network to non-terrestrial network (NTN-NTN). No data forwarding occurs during and / or after the handover. This embodiment differs from Embodiment 10 in that it specifies the timing of data transmission, i.e., immediately after handover preparation is completed. Other steps or operations are the same as or similar to those in the above embodiments.

[0183] Example 22:

[0184] The handover process includes conditional handover. Before the handover decision and after handover preparation, data is transmitted from network nodes to the serving / source node and one or more target nodes. The network nodes include gateways (GWs), and no packet status information is transmitted from the serving / source node to one or more target nodes. This can reduce signaling load during handovers such as NTN-NTN. There is no data forwarding during and / or after the handover.

[0185] There is no need to transmit the PDCP SN status report from the source satellite to the target satellite. In this case, the target satellite will send the next data packet without a PDCP status report, which may be determined by the network implementation; the UE can perform duplicate detection and discarding itself, which may be determined by the UE. Other steps or operations are the same as or similar to those in the above embodiments.

[0186] Example 23:

[0187] Figure 22 As shown, in some embodiments, the handover process includes a Conditional Handover (CHO). Data is transmitted from the network node to the serving / source node and one or more target nodes before the handover decision, after handover preparation, and after the serving / source node sends an indication to the network node. The network node includes a gateway, and packet status is transmitted from the serving / source node to one or more target nodes. This can reduce signaling load during handovers, such as non-terrestrial network to non-terrestrial network (NTN-NTN). No data forwarding occurs during and / or after the handover. The difference between this embodiment and embodiments 11 and 12 is that the data transmission time is after handover preparation is completed and after waiting for the UE to send an indication to the source satellite. Other steps or operations are the same as or similar to those in the above embodiments.

[0188] Example 24:

[0189] The handover process includes conditional handover. Data is transmitted from the network node to the service / source node and one or more target nodes before the handover decision, after handover preparation, and after the serving / source node sends an instruction to the network node. The network node includes gateways and does not transmit any packet status information from the service / source node to the one or more target nodes. This can reduce signaling load during handovers such as NTN-NTN handovers. No data forwarding occurs during and / or after the handover.

[0190] There is no need to send the PDCP sequence number status report from the source satellite to the target satellite. In this case, the target satellite will send the next data packet without a PDCP status report, which can be handled by the network side; the UE can perform duplicate detection and discarding itself, which can be handled by the UE. Other steps or operations are the same as or similar to those in the above embodiments.

[0191] Figure 23 This is a block diagram of an example system 700 for wireless communication according to an embodiment of this application. The various embodiments described herein can be implemented in this system by any suitably configured hardware and / or software. Figure 23 The system 700 is shown to include radio frequency (RF) circuitry 710, baseband circuitry 720, application circuitry 730, memory / storage device 740, display 750, camera 760, sensor 770, and input / output (I / O) interface 780. These components are interconnected with each other at least as shown in the figure. The application circuitry 730 may include circuitry such as one or more single-core or multi-core processors. The processor may include any combination of general-purpose and special-purpose processors, such as graphics processors, application processors, etc. The processor may be connected to the memory / storage device and configured to execute instructions stored in the memory / storage device to implement the functions of various applications and / or operating systems running on the system.

[0192] Although this application has been described in conjunction with embodiments considered to be most practical and preferred, it should be understood that this application is not limited to the disclosed embodiments, but is intended to cover various modifications and arrangements made without departing from the broadest interpretation of the appended claims.

Claims

1. A network handover enhancement method, executed by a network system, characterized in that, include: Before the switching process, data is transmitted from network nodes of the network system to the service / source node and one or more target nodes.

2. The network handover enhancement method according to claim 1, characterized in that, The data is transmitted by the network node to the serving / source node and the one or more target nodes before the handover process, rather than being forwarded during and / or after the handover.

3. The network handover enhancement method according to claim 1 or 2, characterized in that, The data is further transmitted to the user equipment (UE) by the one or more target nodes during and / or after the handover process is completed.

4. The network handover enhancement method according to any one of claims 1 to 3, characterized in that, The service / source node includes a service / source satellite or a service / source base station, and the one or more target nodes include one or more target satellites or one or more target base stations.

5. The network handover enhancement method according to any one of claims 1 to 4, characterized in that, The network handover enhancement method is implemented in the next-generation radio access network (NG-RAN) architecture based on non-terrestrial network (NTN).

6. The network handover enhancement method according to claim 5, characterized in that, The NTN-based NG-RAN architecture includes a transparent satellite-based NG-RAN architecture, a regenerative satellite-based NG-RAN architecture, and / or involves multiple connections of NTN-based NG-RAN.

7. The network handover enhancement method according to claim 6, characterized in that, The NG-RAN architecture based on regenerative satellites includes gNB processing payloads, gNB-DU processing payloads, and / or gNB processing payloads based on relay-style architectures.

8. The network handover enhancement method according to claim 6 or 7, characterized in that, If the serving / source node includes the serving / source satellite, and the one or more target nodes include the one or more target satellites, then the network handover enhancement method is executed in the regenerable satellite-based NG-RAN architecture with the gNB processing payload, and the regenerable satellite-based NG-RAN architecture includes regenerable satellites with inter-satellite links (ISL) or regenerable satellites without the ISL.

9. The network handover enhancement method according to claim 6 or 7, characterized in that, If the serving / source node includes the serving / source base station, and the one or more target nodes include the one or more target base stations, then the network handover enhancement method is executed in the transparent satellite-based NG-RAN architecture, or in the regenerative satellite-based NG-RAN architecture with the gNB-DU processing payload.

10. The network handover enhancement method according to any one of claims 1 to 9, characterized in that, The switching process includes normal switching or conditional switching.

11. The network handover enhancement method according to any one of claims 1 to 10, characterized in that, Prior to the handover process, the data is transmitted from the network node to the serving / source node and the one or more target nodes, and the process further includes: Before making a switching decision, the network node transmits the data to the service / source node and the one or more target nodes; After the handover preparation but before the handover decision is made, the network node transmits the data to the serving / source node and the one or more target nodes; or After the service / source node sends an instruction to the network node, and after the handover preparation and before the handover decision is made, the network node transmits the data to the service / source node and the one or more target nodes.

12. The network handover enhancement method according to any one of claims 1 to 11, characterized in that, The network nodes include the core network (CN) or gateways.

13. The network handover enhancement method according to any one of claims 1 to 12, characterized in that, Also includes: Determine whether the data packet is being transmitted from the service / source node to the one or more target nodes.

14. The network handover enhancement method according to claim 13, characterized in that, The data packet status includes the Packet Data Convergence Protocol (PDCP) Sequence Number (SN) status.

15. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes normal switching; The data is transmitted by the network node to the service / source node and the one or more target nodes before the switching decision is made; The network node includes the CN; as well as The data packet status is transmitted from the service / source node to the one or more target nodes.

16. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes normal switching; The data is transmitted by the network node to the service / source node and the one or more target nodes before the switching decision is made; The network node includes the CN; as well as The service / source node has not transmitted any data packets to the one or more target nodes.

17. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes normal switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation and before the handover decision is made; The network node includes the CN; and The data packet status is transmitted from the service / source node to the one or more target nodes.

18. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes normal switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation and before the handover decision is made; The network node includes the CN; as well as The service / source node has not transmitted any data packets to the one or more target nodes.

19. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes normal switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation is completed and before the handover decision is made, and after the service / source node sends an instruction to the network node. The network node includes the CN; and The data packet status is transmitted from the service / source node to the one or more target nodes.

20. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes normal switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation is completed and before the handover decision is made, and after the service / source node sends an instruction to the network node. The network node includes the CN; as well as The service / source node has not transmitted any data packets to the one or more target nodes.

21. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes the condition switching; The data is transmitted by the network node to the service / source node and the one or more target nodes before the switching decision is made; The network node includes the CN; and The data packet status is transmitted from the service / source node to the one or more target nodes.

22. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes the condition switching; The data is transmitted by the network node to the service / source node and the one or more target nodes before the switching decision is made; The network node includes the CN; as well as The service / source node has not transmitted any data packets to the one or more target nodes.

23. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes the condition switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation and before the handover decision is made; The network node includes the CN; and The data packet status is transmitted from the service / source node to the one or more target nodes.

24. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes the condition switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation and before the handover decision is made; The network node includes the CN; as well as The service / source node has not transmitted any data packets to the one or more target nodes.

25. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes the condition switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation is completed and before the handover decision is made, and after the service / source node sends an instruction to the network node. The network node includes the CN; and The data packet status is transmitted from the service / source node to the one or more target nodes.

26. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes the condition switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation is completed and before the handover decision is made, and after the service / source node sends an instruction to the network node. The network node includes the CN; as well as The service / source node has not transmitted any data packets to the one or more target nodes.

27. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes normal switching; The data is transmitted by the network node to the service / source node and the one or more target nodes before the switching decision is made; The network node includes a gateway; and The data packet status is transmitted from the service / source node to the one or more target nodes.

28. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes normal switching; The data is transmitted by the network node to the service / source node and the one or more target nodes before the switching decision is made; The network node includes a gateway; and The service / source node has not transmitted any data packets to the one or more target nodes.

29. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes normal switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation and before the handover decision is made; The network node includes a gateway; and The data packet status is transmitted from the service / source node to the one or more target nodes.

30. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes normal switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation and before the handover decision is made; The network node includes a gateway; and The service / source node has not transmitted any data packets to the one or more target nodes.

31. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes normal switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation is completed and before the handover decision is made, and after the service / source node sends an instruction to the network node. The network node includes a gateway; and The data packet status is transmitted from the service / source node to the one or more target nodes.

32. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes normal switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation is completed and before the handover decision is made, and after the service / source node sends an instruction to the network node. The network node includes a gateway; and The service / source node has not transmitted any data packets to the one or more target nodes.

33. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes the condition switching; The data is transmitted by the network node to the service / source node and the one or more target nodes before the switching decision is made; The network node includes a gateway; and The data packet status is transmitted from the service / source node to the one or more target nodes.

34. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes the condition switching; The data is transmitted by the network node to the service / source node and the one or more target nodes before the switching decision is made; The network node includes a gateway; and The service / source node has not transmitted any data packets to the one or more target nodes.

35. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes the condition switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation and before the handover decision is made; The network node includes a gateway; and The data packet status is transmitted from the service / source node to the one or more target nodes.

36. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes the condition switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation and before the handover decision is made; The network node includes a gateway; and The service / source node has not transmitted any data packets to the one or more target nodes.

37. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes the condition switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation is completed and before the handover decision is made, and after the service / source node sends an instruction to the network node. The network node includes a gateway; and The data packet status is transmitted from the service / source node to the one or more target nodes.

38. The network handover enhancement method according to claim 13 or 14, characterized in that, The switching process includes the condition switching; The data is transmitted by the network node to the service / source node and the one or more target nodes after the handover preparation is completed and before the handover decision is made, and after the service / source node sends an instruction to the network node. The network node includes a gateway; and The service / source node has not transmitted any data packets to the one or more target nodes.

39. A network handover enhancement method, executed by a network node, characterized in that, include: Before the handover process, the network node transmits data to the service / source node and one or more target nodes.

40. A network system, characterized in that, include: Network nodes, service / source nodes, and / or one or more target nodes; The network node, the service / source node, and / or the one or more target nodes are configured to perform the method of any one of claims 1 to 38.

41. A network node, characterized in that, include: Memory; transceiver; as well as A processor connected to the memory and the transceiver; The transceiver is configured to transmit data to the service / source node and one or more target nodes before the handover process.

Images