Network switching method

Abstract

The invention discloses a network switching method. The method comprises the steps that a switching command is received, the switching command is used for indicating a terminal to be switched from a currently accessed source base station to any candidate base station, and the switching command carries configuration information of a plurality of candidate base stations; under the condition that the configuration information comprises uplink authorization configuration, switching the source base station to a target base station based on a first type of uplink resources indicated by the uplink authorization configuration, the target base station belonging to the candidate base station; and under the condition that the configuration information does not comprise the uplink authorization configuration or the uplink authorization configuration is invalid, switching the source base station to the target base station based on a second type of uplink resources related to a dynamic scheduling indication, the dynamic scheduling indication being sent by the source base station. According to the invention, the technical problem of high delay of satellite-ground switching caused by the fact that a network switching method in a ground communication network is not suitable for a satellite-ground switching scene is solved.

Description

Technical Field

[0001] This application relates to the field of communication technology, and more specifically, to a method for network switching. Background Technology

[0002] With the rapid development of 5G non-terrestrial network (NTN) technology, satellite communication is increasingly being used in scenarios such as the Internet of Things (IoT) and emergency communication. Some key technologies in traditional terrestrial communication networks, such as handover mechanisms and random access protocol (RACH), are difficult to directly apply to NTN environments. Therefore, related technologies suffer from high latency, high signaling overhead, and poor signal quality during satellite-to-ground handover (or ground-to-satellite handover, referring to the mutual switching between satellite and terrestrial networks).

[0003] There is currently no effective solution to the above problems. Summary of the Invention

[0004] This application provides a network handover method to at least solve the technical problem of high latency in satellite-to-ground handover caused by the inapplicability of network handover methods in terrestrial communication networks to satellite-to-ground handover scenarios.

[0005] According to one aspect of the embodiments of this application, a network handover method is provided, comprising: receiving a handover command, wherein the handover command is used to instruct a terminal to switch from a currently accessed source base station to any candidate base station, and the handover command carries configuration information of multiple candidate base stations; if the configuration information includes uplink grant configuration, switching the source base station to a target base station based on a first type of uplink resources indicated by the uplink grant configuration, wherein the target base station is a candidate base station; if the configuration information does not include uplink grant configuration or the uplink grant configuration is invalid, switching the source base station to the target base station based on a second type of uplink resources related to a dynamic scheduling instruction, wherein the dynamic scheduling instruction is sent by the source base station.

[0006] Optionally, when the configuration information includes uplink grant configuration, the process includes: parsing multiple uplink grant configurations to obtain multiple target uplink resource scheduling parameters, wherein each target uplink resource scheduling parameter corresponds to a candidate base station, and the target uplink resource scheduling parameters are control information used to guide the terminal to perform uplink transmission to the candidate base station, and the uplink resource scheduling parameters include at least: timing advance and transmit power; sending a reconfiguration completion message to the source base station through the first type of uplink resources, wherein the reconfiguration completion message is used to indicate that the terminal has received the target uplink resource scheduling parameters.

[0007] Optionally, switching the source base station to the target base station includes: the terminal continuously detecting the terminal's communication environment information, wherein the communication environment information includes at least: the location of each candidate cell and the signal strength of each candidate cell, and the candidate cell is a cell included in the candidate base station; determining the target cell based on the communication environment information, wherein the target cell is the candidate cell to which the terminal will switch; after determining the target cell, the terminal removes attachment from the source base station and synchronizes with the target base station according to the uplink authorization configuration of the target base station, wherein the target base station is the candidate base station to which the target cell belongs.

[0008] Optionally, determining the target cell based on communication environment information includes: comparing the environment information of each candidate cell recorded in the communication environment information with the cell environment information recorded in the preset network handover conditions, wherein the cell environment information recorded in the preset network handover conditions includes at least: the real-time location of the terminal and a signal strength threshold; and determining the candidate cell with a signal strength greater than the signal strength threshold and a location closest to the real-time location of the terminal as the target cell.

[0009] Optionally, when the source base station is a terrestrial base station and the target base station is a satellite base station, the uplink authorization configuration also includes: the ephemeris information of the target base station.

[0010] Optionally, if the uplink authorization configuration includes the ephemeris information of the target base station, the terminal determines the timing advance to be used when synchronizing uplink with the target base station based on the ephemeris information.

[0011] Optionally, the network handover method further includes: in the event that no uplink grant configuration is received or the uplink grant configuration has failed, and no dynamic scheduling indication is detected in the physical downlink control channel, network handover is achieved by sending a random access preamble to the candidate base station, wherein the physical downlink control channel is a channel between the terminal and the source base station used to transmit uplink synchronization control information and downlink synchronization control information.

[0012] According to another aspect of the embodiments of this application, a network handover method is also provided, comprising: upon receiving a handover request response returned by at least one candidate base station, sending a handover command to a terminal, wherein the handover request response is used to indicate that the candidate base station supports terminal access, the handover command is used to indicate that the terminal switches from the currently accessed source base station to any candidate base station, the handover command carries configuration information of multiple candidate base stations, the configuration information of the candidate base stations including: uplink authorization configuration; monitoring the result of the terminal performing a network handover operation based on a first type of uplink resources indicated by the uplink authorization configuration, wherein the network handover operation is an operation in which the terminal switches from the currently accessed source base station to a target base station, the target base station being a candidate base station; and if the result indicates that the network handover operation has failed, sending a dynamic scheduling instruction to the terminal.

[0013] Optionally, before receiving a handover request response from at least one candidate base station, the process includes: sending measurement control information to the terminal, wherein the measurement control information instructs the terminal to perform wireless measurements on itself and report the results of the wireless measurements, the wireless measurements instructing the terminal to evaluate the quality of the wireless link between itself and the current serving cell, the current serving cell being a cell included in the source base station; receiving response information from the measurement control information, and determining whether to perform a network handover based on the response information; if it is determined that a network handover should be performed, sending handover requests to multiple candidate base stations, wherein the handover requests instruct the candidate base stations to evaluate the access feasibility of the terminal.

[0014] According to another aspect of the embodiments of this application, a network handover method is also provided, comprising: a candidate base station broadcasting a synchronization signal to a terminal, wherein the synchronization signal is used to support downlink synchronization between the terminal and the candidate base station; receiving an uplink signal sent by the terminal through a first type of uplink resource indicated by an uplink grant configuration, wherein the uplink signal includes: uplink information and timing advance of the terminal, and the uplink grant configuration is included in the configuration information of the candidate base station; upon receiving a handover request, evaluating the feasibility of terminal access based on the uplink signal; and if the evaluation result obtained from evaluating the feasibility of terminal access based on the uplink signal indicates support for terminal access, returning a handover request response to the source base station that sent the handover request, wherein the handover request response is used to indicate that the candidate base station supports terminal access.

[0015] In this embodiment, a handover command is received, instructing the terminal to switch from the currently accessed source base station to any candidate base station. The handover command carries configuration information for multiple candidate base stations. If the configuration information includes uplink grant configuration, the source base station is switched to the target base station based on the first type of uplink resources indicated by the uplink grant configuration, where the target base station is a candidate base station. If the configuration information does not include uplink grant configuration or the uplink grant configuration is invalid, the source base station is switched to the target base station based on the second type of uplink resources related to the dynamic scheduling indication. This satellite-to-ground handover is achieved by combining the use of uplink grant configuration (CG) and dynamic scheduling indication (DG). When the CG resources meet the usage conditions, the satellite-to-ground handover is directly completed using the grant resources indicated by the CG. When the CG resources do not meet the usage conditions, the terminal falls back to a RACH-less HO mechanism by listening to DG information. The HO mechanism completes the satellite-to-ground handover, thereby reducing the latency of the satellite-to-ground handover and improving the efficiency of the satellite-to-ground handover. It also reduces the signaling overhead during the handover process, thus solving the technical problem of high latency in satellite-to-ground handover caused by the inapplicability of network handover methods in terrestrial communication networks to satellite-to-ground handover scenarios. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0017] Figure 1 This is a schematic diagram of a communication system 100 according to an embodiment of this application;

[0018] Figure 2 This is a flowchart illustrating the steps of a network handover method according to an embodiment of this application;

[0019] Figure 3 This is a flowchart of a RACH-less HO mechanism according to an embodiment of this application;

[0020] Figure 4 This is a flowchart of another network handover method according to an embodiment of this application;

[0021] Figure 5 This is a flowchart illustrating the steps of another network handover method according to an embodiment of this application;

[0022] Figure 6 This is a full flowchart of a network switching method according to an embodiment of this application. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0025] To better understand the embodiments of this application, the technical terms involved in the embodiments of this application are explained below:

[0026] Dynamic Grant (DG): In wireless communication systems, Dynamic Grant (DG) is an important resource allocation mechanism; it allows the network (usually the base station) to dynamically allocate uplink (UL) or downlink (DL) resources based on real-time network conditions and the transmission needs of user terminals (UEs).

[0027] Uplink Grant (CG): A pre-configured uplink resource allocation mechanism in a wireless communication system; it allows user terminals (UEs) to use configured resources for uplink data transmission without real-time network scheduling.

[0028] Conditional Handover (CHO): A handover mechanism mainly used in wireless communication networks. CHO allows user terminals (UEs) to perform handover only when specific preset conditions are met.

[0029] Cell: The basic unit of network coverage, which defines the geographical area covered by the base station.

[0030] In related technologies, RACH-less HO (Random Access Without Handover) has been introduced to improve the mobility of NTNs. RACH-less HO is a technique used to reduce handover latency and signaling overhead, applied to handovers within the same satellite or between satellites. However, due to the unique propagation characteristics of satellite-to-ground and ground-to-satellite handovers, such as significant round-trip time (RTT) and continuous satellite movement, the application of RACH-less HO in satellite-to-ground handover still faces challenges. For example, due to the high speed of satellite movement, the user equipment (UE) may not be able to accurately judge changes in signal quality during handover, leading to handover failure. Furthermore, since satellite-to-ground handover involves different network types (terrestrial and satellite networks), the synchronization and configuration during handover are complex. Therefore, the aforementioned network handover methods cannot be directly applied to satellite-to-ground handover scenarios, resulting in high latency and high signaling overhead. To address these issues, this application provides relevant solutions, which are detailed below.

[0031] According to an embodiment of this application, a method embodiment for network switching is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0032] The technical solutions of this application embodiment can be applied to various communication systems, such as: Global System of Mobile communication (GSM) system, Code Division Multiple Access (CDMA) system, Wideband Code Division Multiple Access (WCDMA) system, General Packet Radio Service (GPRS), Long Term Evolution (LTE) system, LTE Frequency Division Duplex (FDD) system, LTE Time Division Duplex (TDD) system, Universal Mobile Telecommunication System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX) communication system, or 5G system, etc.

[0033] Figure 1 This is a schematic diagram of a communication system 100, which is exemplary. The communication system 100 used in this embodiment of the application is as follows: Figure 1 As shown. The communication system 100 may include a network device 110, which may be a device that communicates with a terminal device 120 (or a communication terminal, terminal). The network device 110 can provide communication coverage for a specific geographical area and can communicate with terminal devices located within that coverage area. Optionally, the network device 110 may be a base station (BTS) in a GSM or CDMA system, a base station (NodeB, NB) in a WCDMA system, an evolved Node B (eNB or eNodeB) in an LTE system, or a radio controller in a Cloud Radio Access Network (CRAN). Alternatively, the network device may be a mobile switching center, relay station, access point, vehicle-mounted equipment, wearable device, hub, switch, bridge, router, network-side equipment in a 5G network, or network equipment in a future evolved Public Land Mobile Network (PLMN), etc.

[0034] The communication system 100 also includes at least one terminal device 120 located within the coverage area of ​​network device 110. As used herein, "terminal device" includes, but is not limited to, devices configured to receive / transmit communication signals via wired connections, such as via Public Switched Telephone Networks (PSTN), Digital Subscriber Line (DSL), digital cable, direct cable connection; and / or another data connection / network; and / or via a wireless interface, such as for cellular networks, Wireless Local Area Network (WLAN), digital television networks such as DVB-H networks, satellite networks, AM-FM radio transmitters; and / or other terminal devices. Terminal devices configured to communicate via wireless interfaces may be referred to as "wireless communication terminal," "wireless terminal," or "mobile terminal." Examples of mobile terminals include, but are not limited to, satellite or cellular phones; personal communications system (PCS) terminals that can combine cellular radiotelephony with data processing, fax, and data communication capabilities; PDAs that may include radiotelephones, pagers, Internet / intranet access, web browsers, notebooks, calendars, and / or Global Positioning System (GPS) receivers; and conventional laptop and / or handheld receivers or other electronic devices that include radiotelephone transceivers. Terminal equipment can refer to access terminals, user equipment (UE), user units, user stations, mobile stations, mobile stations, remote stations, remote terminals, mobile devices, user terminals, terminals, wireless communication equipment, user agents, or user equipment. Access terminals can be cellular phones, cordless phones, Session Initiation Protocol (SIP) phones, Wireless Local Loop (WLL) stations, Personal Digital Assistants (PDAs), handheld devices with wireless communication capabilities, computing devices or other processing devices connected to a wireless modem, in-vehicle devices, wearable devices, terminal devices in 5G networks, or terminal devices in future PLMNs, etc.

[0035] Optionally, the terminal devices 120 can perform device-to-device (D2D) communication with each other.

[0036] Alternatively, a 5G system or 5G network may also be referred to as a New Radio (NR) system or NR network.

[0037] This application provides a network switching method that can be applied in the above-described operating environment. Figure 2 This is a flowchart of the network handover method provided in the embodiments of this application, as follows: Figure 2 As shown, the method includes the following steps:

[0038] Step S202: Receive a handover command, wherein the handover command is used to instruct the terminal to switch from the currently accessed source base station to any candidate base station, and the handover command carries configuration information of multiple candidate base stations.

[0039] This application provides a method for achieving satellite-to-ground network handover by combining the random access-free (RACH-less HO) mechanism with the conditional handover (CHO) mechanism. In this application, satellite-to-ground handover refers to the mutual handover between the satellite network and the terrestrial network. That is, satellite-to-ground handover can refer to switching from the satellite network to the terrestrial network, or it can refer to switching from the terrestrial network to the satellite network. Figure 3 This is a flowchart of the RACH-less HO mechanism, such as... Figure 3 As shown, when using the RACH-less HO mechanism provided in this application embodiment, the terminal (UE) no longer establishes an initial connection with the base station to be switched to (i.e., the target base station, T-gNB) through a random access channel. Instead, it performs the handover based on the resources provided by the uplink grant configuration (CG) carried in the handover command (HO Command) sent by its currently accessed base station (i.e., the source base station, S-gNB). That is, when performing satellite-to-ground handover using the method provided in this application embodiment, as described in step S202, the terminal will receive the handover command (HO Command) sent by the currently accessed base station (source base station, S-gNB), such as... Figure 3 As shown, the switching command carries a pre-allocated grant (Opt), N TA In this case, the pre-allocated authorization record is recorded in the configuration information. If there are multiple base stations that can be switched to within the range of the terminal (i.e., candidate base stations), the switching command carries the configuration information of each candidate base station.

[0040] Step S204: If the configuration information includes uplink authorization configuration, the source base station is switched to the target base station based on the first type of uplink resources indicated by the uplink authorization configuration, wherein the target base station is a candidate base station.

[0041] In the method provided in this application embodiment, if the configuration information carried by the handover command includes the uplink grant configuration (CG) of each candidate base station, then in step S204, when the terminal initially performs uplink transmission, it preferentially selects the resources associated with the CG (i.e., the first type of uplink resources), and realizes uplink and downlink synchronization with the base station to be handed over to (i.e., the target base station, T-gNB) based on the resources associated with the CG, and further completes the network handover; wherein, the base station to be handed over to (T-gNB) is a base station in the candidate set that meets the conditional handover (CHO). The conditional handover (CHO) includes a series of network-preset triggering conditions, such as recording information such as the signal quality requirements of the target base station. When the signal quality of a candidate base station meets the signal quality requirements recorded in the conditional handover (CHO), the terminal will automatically trigger the handover to the target base station.

[0042] According to some optional embodiments of this application, when the configuration information includes uplink grant configuration, the method includes: parsing multiple uplink grant configurations to obtain multiple target uplink resource scheduling parameters, wherein each target uplink resource scheduling parameter corresponds to a candidate base station, and the target uplink resource scheduling parameters are control information used to guide the terminal to perform uplink transmission to the candidate base station, and the uplink resource scheduling parameters include at least: timing advance and transmit power; sending a reconfiguration completion message to the source base station through the first type of uplink resources, wherein the reconfiguration completion message is used to indicate that the terminal has received the target uplink resource scheduling parameters.

[0043] In this embodiment, after receiving the configuration information, the terminal parses and stores the received configuration information, and then sends a reconfiguration completion message to the source base station. This message informs the source base station that the terminal has correctly received and understood the reconfiguration message, and also indicates that the terminal is currently in a handover preparation state. The terminal's parsing of the received configuration information includes parsing the uplink grant configuration (CG). Parsing the uplink grant configuration (CG) allows the terminal to extract the timing advance (TA), transmit power, and other uplink resource scheduling parameters recorded in each uplink grant configuration (CG). These uplink resource scheduling parameters are used to guide the terminal in uplink transmission to candidate base stations, where each uplink grant configuration (CG) corresponds to one candidate base station.

[0044] According to another optional embodiment of this application, switching a source base station to a target base station includes: the terminal continuously detecting the terminal's communication environment information, wherein the communication environment information includes at least: the location of each candidate cell and the signal strength of each candidate cell, and the candidate cell is a cell included in the candidate base station; determining a target cell based on the communication environment information, wherein the target cell is the candidate cell to which the terminal will switch; after determining the target cell, the terminal removes attachment from the source base station and synchronizes with the target base station according to the uplink grant configuration of the target base station, wherein the target base station is the candidate base station to which the target cell belongs.

[0045] In the method provided in this application embodiment, when network handover is implemented based on the RACH-less HO mechanism, after receiving the uplink grant configuration (CG), the conditional handover (CHO) mechanism will be initiated. The purpose of initiating the conditional handover (CHO) mechanism is to determine whether there is a candidate cell (i.e., target cell) that meets the preset handover conditions among the candidate cells based on the information of the monitored candidate cells. After the conditional handover (CHO) mechanism is initiated, the terminal continuously monitors the environmental information (i.e., communication environment information) around it. Specifically, the terminal will monitor the location of each candidate cell within the coverage area of ​​the candidate base station, the signal strength of each candidate cell, and other information related to the terminal's communication quality. The monitoring of the signal strength of each candidate cell can be achieved by periodically receiving the synchronization signal / physical broadcast channel block (SSB) signal of the candidate cell. The terminal determines whether there is a (target) cell that meets the preset network handover conditions based on the relevant information of each candidate cell it monitors. If there is, the terminal will unattach itself from the base station it is currently accessing (i.e., the source base station) (i.e., stop uplink transmission with the source base station and prepare to establish a new communication link with the target base station). Then, it uses the uplink license configuration (CG) corresponding to the candidate base station (i.e., the target base station) to which the target cell belongs, adjusts its own uplink transmission timing advance (TA) and transmit power, and uses the resources associated with the uplink license configuration (CG) (i.e., the first type of uplink resources) to perform uplink transmission to the target base station, thus completing the uplink synchronization process with the target base station.

[0046] Optionally, determining the target cell based on communication environment information includes: comparing the environment information of each candidate cell recorded in the communication environment information with the cell environment information recorded in the preset network handover conditions, wherein the cell environment information recorded in the preset network handover conditions includes at least: the real-time location of the terminal and a signal strength threshold; and determining the candidate cell with a signal strength greater than the signal strength threshold and a location closest to the real-time location of the terminal as the target cell.

[0047] The Conditional Handover (CHO) mechanism works by having the source base station pre-configure a series of handover conditions for the terminal. These conditions may include: radio link quality parameters (such as signal strength, signal quality, and interference levels), the terminal's movement (such as speed and direction), or changes in network topology. While continuously monitoring the communication environment, the terminal evaluates whether any of the configured handover conditions are met. Once the terminal detects that the current communication environment meets any of the preset network handover conditions, it will automatically perform the handover without waiting for further instructions from the source base station. In this embodiment, when the terminal continuously detects communication environment information, it determines the (target) cell that meets the preset network handover conditions through the following method: The terminal compares the relevant information (location and signal strength of the candidate cell) of each candidate cell obtained by detecting communication environment information with the signal strength threshold (e.g., -100 dBm) recorded in a series of handover conditions (i.e., preset network handover conditions) pre-configured to the terminal by the source base station. At the same time, it calculates the distance between the terminal and each candidate cell based on the location of the candidate cell and the real-time location of the terminal (which can be represented by path loss, with smaller path loss indicating a closer distance). The candidate cell with a signal strength greater than the above-mentioned signal strength threshold and the closest distance to the terminal (minimum path loss) is determined as the cell that the terminal will switch to (i.e., the target cell).

[0048] Step S206: If the uplink authorization configuration is not included in the configuration information or the uplink authorization configuration is invalid, the source base station is switched to the target base station based on the second type of uplink resources related to the dynamic scheduling instruction, wherein the dynamic scheduling instruction is sent by the source base station.

[0049] like Figure 3As shown, the method provided in this application embodiment also includes a dynamic uplink resource allocation (Dynamic ULGrant) scenario. In this dynamic uplink resource allocation, the resources associated with the Dynamic Grant (DG) (i.e., the second type of uplink resources) are allocated. The purpose of allocating the resources associated with the Dynamic Grant (DG) is to achieve network handover based on these resources. The aforementioned use of resources associated with the Dynamic Grant (DG) to achieve network handover occurs when the resources associated with the Uplink Grant Configuration (CG) are not configured or are unavailable. In step S206, if the configuration information carried by the handover command does not include the Uplink Grant Configuration (CG), it indicates that the resources associated with the Uplink Grant Configuration (CG) are not configured. If the Synchronization Signal Block (Signal Block) associated with the Uplink Grant Configuration (CG) is not configured... If the signal quality of a Block (SSB) is poor, the resources associated with the Uplink Grant Configuration (CG) are considered unusable and therefore unavailable. In this case, the terminal needs to listen for a Dynamic Dispatch Instruction (DG) to perform network handover based on the resources associated with the DG. Typically, the DG is issued by the base station currently accessed by the terminal (i.e., the source base station) via the Physical Downlink Control Channel (PDCCH). Whether the signal quality of the SSB associated with the Uplink Grant Configuration (CG) is good or bad can be determined by preset radio link evaluation indicators and... The actual situation of the SSB signal can be used to determine whether the signal quality of the SSB associated with the uplink license configuration (CG) is good or bad. For example, if the preset radio link evaluation indicators include the minimum value of the reference signal received power (RSRP), the minimum value of the reference signal received quality (RSRQ), and the minimum value of the signal-to-interference-plus-noise ratio (SINR) of the SSB signal, the actual reference signal received power (RSRP), the actual reference signal received quality (RSRQ), and the actual signal-to-interference-plus-noise ratio (SINR) of the SSB signal are compared with the information recorded in the preset radio link evaluation indicators.

[0050] Optionally, the network handover method further includes: in the event that no uplink grant configuration is received or the uplink grant configuration has failed, and no dynamic scheduling indication is detected in the physical downlink control channel, network handover is achieved by sending a random access preamble to the candidate base station, wherein the physical downlink control channel is a channel between the terminal and the source base station used to transmit uplink synchronization control information and downlink synchronization control information.

[0051] like Figure 3As shown, when implementing the RACH-less handover mechanism, there is still a possibility that the target base station (T-gNB) sends a Media Access Control Contention Resolution MAC CE to the terminal. Specifically, the sending of the RACH-less handover mechanism by the target base station (T-gNB) to the terminal occurs when network handover is implemented using a Random Access Channel (RACH), i.e., the RACH-less handover mechanism provided by the method in this application embodiment. The HO mechanism includes the use of the Random Access Channel (RACH) for network handover. In this embodiment, the use of the Random Access Channel (RACH) for network handover occurs when the resource configuration associated with the Uplink Grant Configuration (CG) is unavailable, and the terminal does not detect the Dynamic Scheduling Indicator (DG) in the Physical Downlink Control Channel (PDCCH) between the terminal and the currently accessing base station (i.e., the source base station). That is, in the method provided in this application embodiment, when the terminal has neither available CG resources nor received DG information, the terminal will initiate the Random Access Procedure (RACH) to request uplink resources. Specifically, the terminal will first send a random access preamble to the candidate base station and continue to perform the relevant operations of random access (RACH-based Handover) to complete the network handover. The aforementioned operations for continuing random access (RACH-based Handover) specifically include: the terminal waiting to receive a random access response (RAR) from the candidate base station, wherein the random access response (RAR) contains a temporary grant for uplink transmission and other necessary synchronization information; after receiving the random access response (RAR), the terminal uses the temporary grant and other synchronization information provided in the random access response (RAR) to send a handover request or terminal identity information on the designated uplink shared channel (PUSCH) so that the candidate base station can further process it; if the terminal obtains uplink grant from the candidate base station, it can switch from the source base station to the candidate base station, completing the network handover process.

[0052] According to some optional embodiments of this application, when the source base station is a terrestrial base station and the target base station is a satellite base station, the uplink authorization configuration also includes: ephemeris information of the target base station.

[0053] Unlike ground handover, satellite-to-ground handover needs to take into account the satellite's trajectory. Therefore, if the terminal is performing the method provided in this application embodiment to switch from a ground communication base station to a satellite base station, the uplink authorization configuration (CG) should also include the ephemeris information of the satellite base station. The ephemeris information is used for the terminal to synchronize with the target base station.

[0054] Optionally, if the uplink authorization configuration includes the ephemeris information of the target base station, the terminal determines the timing advance to be used when synchronizing uplink with the target base station based on the ephemeris information.

[0055] The ephemeris information includes key data such as the orbital parameters, current position, and velocity of the satellite to which the satellite base station belongs. In this embodiment, after obtaining the ephemeris information, the terminal uses the satellite's orbital parameters, current position, and velocity to calculate the satellite's exact position at the point when uplink synchronization is about to occur. The terminal also calculates its own propagation delay to the satellite base station, which depends on the distance between the terminal and the satellite base station. The terminal converts the calculated propagation delay into a timing advance (TA), which is used to adjust the uplink signal transmission time to ensure that the uplink signal can be correctly captured within the satellite base station's reception window. The terminal reconfigures its uplink parameters based on the calculated timing advance (TA) and uses the reconfigured uplink parameters to perform uplink synchronization with the target base station.

[0056] Through the above steps, a satellite-to-ground handover can be achieved by combining RACH-less HO and Conditional Handover (CHO) mechanisms, effectively reducing handover latency and signaling overhead. Specifically, by pre-configuring uplink grant (CG) and dynamic scheduling indication (DG), the terminal can complete the satellite-to-ground handover quickly and accurately, avoiding the uncertainties inherent in traditional random access processes and improving data transmission continuity and service quality.

[0057] Figure 4 This is a flowchart of another network handover method provided according to an embodiment of this application, such as... Figure 4 As shown, the method includes the following steps:

[0058] S402, upon receiving a handover request response from at least one candidate base station, a handover command is sent to the terminal. The handover request response indicates that the candidate base station supports the terminal's access, and the handover command indicates that the terminal should switch from the currently accessed source base station to any candidate base station. The handover command carries configuration information of multiple candidate base stations, including uplink authorization configuration.

[0059] When implementing network handover based on the method provided in this application embodiment, the base station currently accessed by the terminal (i.e., the source base station) is responsible for coordinating the handover process between the terminal and multiple candidate base stations. Network handover can only be executed when a handover request response is received from a candidate base station. In step S402, if the source base station determines that it has received a handover request response from a candidate base station, it means that the candidate base station has confirmed that it can support the terminal access. The source base station will then integrate the configuration information of all candidate base stations that have returned handover request responses to generate a handover command. The handover command is used to instruct the terminal to switch from the currently accessed source base station to any candidate base station. The handover command carries the uplink grant configuration (CG) of each candidate base station. The uplink grant configuration includes uplink resource scheduling parameters such as uplink grant time, frequency resources, and timing advance (TA).

[0060] S404, The monitoring terminal performs a network handover operation based on the first type of uplink resources indicated by the uplink authorization configuration. The network handover operation is the operation of the terminal switching from the currently accessed source base station to the target base station, and the target base station is a candidate base station.

[0061] In step S204, the system begins to monitor the results of the network handover operation performed by the terminal based on the resources associated with the uplink grant configuration (CG) (i.e., the first type of uplink resources). The network handover operation refers to the operation by which the terminal switches the currently accessed base station (i.e., the source base station) to the target base station. The target base station is the candidate base station to which the candidate cell (target cell) that meets the preset network handover conditions belongs among multiple cells within the coverage area of ​​the candidate base station.

[0062] S406: If the result indicates that the network handover operation has failed, a dynamic scheduling instruction is sent to the terminal.

[0063] If the source base station detects that the terminal's network handover operation via the resources associated with the uplink grant configuration (CG) has failed, meaning the terminal did not use the target base station's uplink resources for effective data transmission within the expected time, the source base station determines that the network handover operation has failed. In this case, in step S206, the source base station will send a Dynamic Scheduling Instruction (DG) to the terminal via the Physical Downlink Control Channel (PDCCH). The DG provides additional uplink resources (i.e., second-type uplink resources) to support the terminal's network handover operation.

[0064] According to some optional embodiments of this application, before receiving a handover request response from at least one candidate base station, the method includes: sending measurement control information to the terminal, wherein the measurement control information is used to instruct the terminal to perform wireless measurements on itself and report the results of the wireless measurements, the wireless measurements being used to instruct the terminal to evaluate the quality of the wireless link between itself and the current serving cell, the current serving cell being a cell included in the source base station; receiving response information of the measurement control information, and determining whether to perform a network handover based on the response information of the measurement control information; if it is determined that a network handover should be performed, sending a handover request to multiple candidate base stations, wherein the handover request is used to instruct the candidate base stations to evaluate the access feasibility of the terminal.

[0065] The handover request response received in step S402 is the response information of the candidate base station to the handover request sent by the source base station. That is, the source base station sent a handover request to the candidate base station before receiving the handover request response. In this embodiment, the source base station can send handover requests to a maximum of 8 candidate base stations. In this embodiment, the specific process of the source base station sending the handover request is as follows: When performing satellite-to-ground handover, the first step performed by the source base station is to send measurement control information to the terminal. The measurement control information is used to instruct the terminal to perform wireless measurements on itself and report the results of the wireless measurements. When the terminal performs wireless measurements on itself, it mainly evaluates the quality of the wireless link between itself and the current serving cell (the cell within the coverage area of ​​the source base station). The response information of the measurement control information returned by the terminal after performing wireless measurements on itself includes: the quality evaluation parameters of the wireless link between the terminal and each current serving cell. The quality evaluation parameters of the wireless link include: Received Signal Strength Indicator (RSSI), Reference Received Power (RSRP), Reference Received Quality (RSRQ), etc. After receiving the response information of the aforementioned measurement and control information, the source base station determines whether the terminal should perform a network handover. For example, if the response information indicates that the current serving cell resources are strained, a network handover may be triggered. Furthermore, the response information may also include the terminal's location; if it is determined that the terminal is moving out of the source base station's coverage area, a network handover may also be triggered. If a network handover is determined, the source base station sends a handover request to multiple candidate base stations (including satellite base stations and terrestrial base stations). The handover request requests the candidate base stations to assess the feasibility of terminal access. In the method provided in this application embodiment, the source base station may select candidate base stations based on the terminal's direction of movement and network layout.

[0066] It should be noted that, Figure 4 The preferred embodiment of the terminal shown in the example can be found in [reference needed]. Figure 2 The relevant descriptions of the embodiments shown will not be repeated here.

[0067] Figure 5This is a flowchart illustrating the steps of another network handover method according to an embodiment of this application, such as... Figure 5 As shown, the method includes the following steps:

[0068] S502, the candidate base station broadcasts a synchronization signal to the terminal, wherein the synchronization signal is used to support downlink synchronization between the terminal and the candidate base station.

[0069] When implementing network handover based on the method provided in this application embodiment, the candidate base station will initially execute the broadcast synchronization signal operation described in step S502. The synchronization signal includes the primary synchronization signal (PSS), secondary synchronization signal (SSS), and physical broadcast channel (PBCH), etc. The synchronization signal carries information such as the frame structure information of the candidate base station and the identifier (ID) of the candidate cell to help the terminal establish synchronization with the candidate base station.

[0070] S504, Receive uplink signal sent by the terminal through the first type of uplink resources indicated by the uplink grant configuration, wherein the uplink signal includes: the terminal's uplink information and timing advance, and the uplink grant configuration is included in the configuration information of the candidate base station.

[0071] After the candidate base station broadcasts the synchronization signal, in step S504, the uplink spectrum is monitored, and the uplink signal sent by the terminal through the resources associated with the uplink grant configuration (CG) (i.e., the first type of uplink resources) is received. The uplink signal sent by the terminal carries the terminal's uplink information (such as buffer status report (BSR), logical channel group identifier (LCG ID)) and timing advance (TA) calculated by the terminal based on the information in the synchronization signal. The timing advance (TA) is used to synchronize with the candidate base station.

[0072] S506, upon receiving a handover request, assesses the feasibility of terminal access based on uplink signals.

[0073] If a candidate base station receives a handover request from the source base station requesting the candidate base station to evaluate whether it supports terminal access, in step S506, each candidate base station will evaluate whether it supports terminal access based on the information recorded in the uplink signal received in step S504. For example, the candidate base station will determine whether it has enough idle resources to support terminal access based on the terminal's resource allocation.

[0074] S508, if the evaluation result obtained from assessing the feasibility of terminal access based on uplink signals indicates support for terminal access, a handover request response is returned to the source base station that sent the handover request, wherein the handover request response is used to indicate that the candidate base station supports terminal access.

[0075] In step S508, if a candidate base station determines that its idle resources can support terminal access, it is evaluated as supporting terminal access. At this time, the candidate base station supporting terminal access will return a handover request response to the source base station. The handover request response is used to indicate that the candidate base station supports terminal access.

[0076] It should be noted that, Figure 5 The preferred embodiment of the terminal shown in the example can be found in [reference needed]. Figure 2 The relevant descriptions of the embodiments shown will not be repeated here.

[0077] Figure 6 This is a flowchart illustrating the complete steps of the network handover method provided in this application embodiment. Figure 6 This document describes the specific operations performed by the terminal (UE), source base station (S-gNB), candidate base stations (Potential gNBs), and the target base station (T-gNB) to which the terminal ultimately needs to switch when implementing the method provided in the embodiments of this application. During satellite-to-ground handover, handover conditions (CHO) are pre-configured based on satellite movement patterns and the terminal's location information, enabling the terminal to automatically perform network handover when it detects that the handover conditions (CHO) are met. Specific implementation steps are as follows: Figure 6As shown, the process is as follows: 1. The source base station sends measurement control information to the terminal, and the terminal performs measurement reporting based on the measurement control information. 2. The source base station makes a handover decision based on the measurement reporting information returned by the terminal. 3. The source base station sends handover requests to multiple candidate base stations (including the target base station), with a maximum of 8 candidate base stations. 4. After receiving the handover request from the source base station, the candidate base station assesses whether it can admit the UE. 5. If the candidate base station assesses that it can admit the UE, it sends a handover request acknowledgement response to the source base station. 6. The source base station sends a reconfiguration message to the UE, which contains handover commands for the 8 candidate target base stations. The handover commands include necessary pre-allocated uplink resources and ephemeris information of the target cell. 7. The UE configures itself according to the reconfiguration message and sends a reconfiguration complete message to the source base station. 8. The UE continuously evaluates whether candidate cells meet the CHO (Evaluate Choice Conditions). 9. When a candidate target cell meets the CHO condition, the UE detaches from the source cell and synchronizes with the target cell according to the configuration information in the handover command. 10. Uplink and downlink synchronization are completed, and the handover is complete (CHO + less handover copletion).

[0078] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0079] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0080] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0081] The units described as separate components may or may not be physically separate. 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 units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0082] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0083] If the integrated unit is implemented as 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 this application, in essence, or the part that contributes to related technologies, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0084] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method of network handover, characterized by, The method comprises: receiving a handover command, wherein the handover command is used to instruct a terminal to hand over from a source base station currently accessed to any one of candidate base stations, and the handover command carries configuration information of a plurality of candidate base stations; in a case where the configuration information comprises uplink grant configuration, switching the source base station to a target base station based on first type uplink resources indicated by the uplink grant configuration, wherein the target base station belongs to the candidate base stations; in a case where the configuration information does not comprise the uplink grant configuration or the uplink grant configuration is invalid, switching the source base station to the target base station based on second type uplink resources related to dynamic scheduling indication, wherein the dynamic scheduling indication is sent by the source base station.

2. The method of claim 1, wherein, in a case where the configuration information comprises uplink grant configuration, the method comprises: parsing a plurality of the uplink grant configuration to obtain a plurality of target uplink resource scheduling parameters, wherein each target uplink resource scheduling parameter corresponds to one of the candidate base stations, the target uplink resource scheduling parameter is control information used to guide the terminal to perform uplink transmission to the candidate base station, and the uplink resource scheduling parameter at least comprises timing advance and transmission power; sending a reconfiguration completion message to the source base station through the first type uplink resource, wherein the reconfiguration completion message is used to indicate that the terminal receives the target uplink resource scheduling parameter.

3. The method of claim 1, wherein, switching the source base station to a target base station, comprising: the terminal continuously detects terminal communication environment information, wherein the communication environment information at least comprises the location of each candidate cell and the signal strength of each candidate cell, and the candidate cell is a cell included in the candidate base station; determining a target cell according to the communication environment information, wherein the target cell is a candidate cell to which the terminal is to be handed over; after determining the target cell, the terminal removes attachment from the source base station and synchronizes with the target base station according to the uplink grant configuration of the target base station, wherein the target base station is a candidate base station to which the target cell belongs.

4. The method of claim 3, wherein, determining a target cell according to the communication environment information, comprising: comparing the environment information of each candidate cell recorded in the communication environment information with cell environment information recorded in a preset network handover condition, wherein the cell environment information recorded in the preset network handover condition at least comprises the real-time location of the terminal and a signal strength threshold; determining a candidate cell with signal strength greater than the signal strength threshold and closest to the real-time location of the terminal as the target cell.

5. The method of claim 1, wherein, in a case where the source base station is a ground base station and the target base station is a satellite base station, the uplink grant configuration further comprises ephemeris information of the target base station.

6. The method of claim 5, wherein, in a case where the uplink grant configuration comprises the ephemeris information of the target base station, the terminal determines a timing advance to be adopted when synchronizing with the target base station in uplink according to the ephemeris information.

7. The method of claim 1, wherein, the method further comprises: In a case that the uplink grant configuration is not received or the uplink grant configuration is invalid, and the dynamic scheduling indication is not listened in the physical downlink control channel, the network switching is implemented by sending a random access preamble to the candidate base station, wherein the physical downlink control channel is a channel used for transmitting uplink synchronization control information and downlink synchronization control information between the terminal and the source base station.

8. A method of network handover, characterized by, Comprising: In a case that a switching request response returned by at least one candidate base station is received, a switching command is sent to the terminal, wherein the switching request response is used for indicating that the candidate base station supports the terminal access, the switching command is used for indicating that the terminal is switched from a source base station currently accessed to any one of the candidate base stations, and the switching command carries configuration information of the plurality of candidate base stations, and the configuration information of the candidate base station comprises an uplink grant configuration; A result of a network switching operation performed by the terminal based on a first type of uplink resource indicated by the uplink grant configuration is listened, wherein the network switching operation is an operation of switching the terminal from a source base station currently accessed to a target base station, and the target base station belongs to the candidate base station; In a case that the result indicates that the network switching operation is failed, a dynamic scheduling indication is sent to the terminal.

9. The method of claim 8, wherein, Before receiving the switching request response returned by at least one candidate base station, comprising: A measurement control information is sent to the terminal, wherein the measurement control information is used for indicating that the terminal performs a wireless measurement and reports a result obtained by performing the wireless measurement, and the wireless measurement is used for indicating that the terminal evaluates a wireless link quality between the terminal and a current serving cell, and the current serving cell is a cell contained in the source base station; A response information of the measurement control information is received, and whether to perform the network switching is determined according to the response information of the measurement control information; In a case that it is determined to perform the network switching, a switching request is sent to a plurality of candidate base stations, wherein the switching request is used for indicating that the candidate base station evaluates an access feasibility of the terminal.

10. A method of network handover, the method comprising: Comprising: A candidate base station broadcasts a synchronization signal to a terminal, wherein the synchronization signal is used for supporting the terminal to perform downlink synchronization with the candidate base station; An uplink signal sent by the terminal through a first type of uplink resource indicated by an uplink grant configuration is received, wherein the uplink signal comprises uplink information and a timing advance of the terminal, and the uplink grant configuration is contained in configuration information of the candidate base station; In a case that a switching request is received, a feasibility of terminal access is evaluated according to the uplink signal; In a case that an evaluation result obtained by evaluating the feasibility of terminal access according to the uplink signal indicates that the terminal access is supported, a switching request response is returned to a source base station sending the switching request, wherein the switching request response is used for indicating that the candidate base station supports the terminal access.

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