Mobility management method for supporting voice in NB-IoT system for low earth orbit satellite

Abstract

The application relates to the technical field of wireless communication, and provides a mobility management method for supporting voice of an NB-IoT system for a low-orbit satellite, which comprises the following steps: before a service satellite of an NB-IoT terminal in a connected state is changed, sending a terminal context of the NB-IoT terminal to an adjacent satellite base station which can be a target service base station in advance. According to the embodiment of the application, in the scene of RRC connection reconstruction when the NB-IoT terminal in the connected state experiences service satellite change and voice service between the satellite and the ground has not ended, the speed and success rate of the RRC connection reconstruction can be improved, so that the interruption delay of the voice service between the satellite and the ground is reduced.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and in particular to a mobility management method for supporting voice using an NB-IoT system for low-Earth orbit satellites. Background Technology

[0002] With the development of wireless communication technology, it is possible that narrowband Internet of Things (NB-IoT) will be used in low Earth orbit (LEO) satellite systems to support voice services in the future. Based on existing NB-IoT protocols, when an NB-IoT terminal in a Radio Resource Control (RRC) connected state experiences a change in its serving satellite, if the terminal's inter-satellite voice service has not yet ended, it will attempt to re-establish the RRC connection to return to the connected state. In this scenario, it is crucial to improve the speed and success rate of RRC connection re-establishment to reduce the interruption latency of inter-satellite voice services. Summary of the Invention

[0003] The purpose of this application is to provide a mobility management method for voice support using the NB-IoT system for low-Earth orbit satellites. This method enables NB-IoT terminals in a connected state to improve the speed and success rate of RRC connection reconstruction when they experience changes in the serving satellite and initiate RRC connection reconstruction because the inter-satellite voice service has not yet ended, thereby reducing the interruption latency of the inter-satellite voice service.

[0004] To achieve the above objectives, on the one hand, embodiments of this application provide a mobility management method for supporting voice using an NB-IoT system for low-Earth orbit satellites, applied to the satellite-based base station side as the source serving base station, the method comprising:

[0005] Before the serving satellite of an NB-IoT terminal in a connected state changes, the terminal context of the NB-IoT terminal is sent in advance to a neighboring satellite base station that can serve as the target serving base station.

[0006] In the mobility management method of this application embodiment, there is an inter-satellite communication link between the source serving base station and the adjacent satellite-based base station. The step of sending the terminal context of the NB-IoT terminal to the adjacent satellite-based base station that can serve as the target serving base station in advance includes:

[0007] Based on the neighbor cell measurement results of the NB-IoT terminal, the terminal context of the NB-IoT terminal is sent to the target serving base station in advance.

[0008] In the mobility management method of this application embodiment, the step of triggering the early transmission of the terminal context of the NB-IoT terminal to the target serving base station based on the neighbor cell measurement results of the NB-IoT terminal includes:

[0009] In response to receiving the neighbor cell measurement results reported by the NB-IoT terminal, the terminal context of the NB-IoT terminal is sent to the target serving base station in advance.

[0010] In the mobility management method of this application embodiment, there is an inter-satellite communication link between the source serving base station and the adjacent satellite-based base station. The step of sending the terminal context of the NB-IoT terminal to the adjacent satellite-based base station that can serve as the target serving base station in advance includes:

[0011] Based on the time it takes for the NB-IoT terminal to leave the coverage area of ​​the source serving base station, the terminal context of the NB-IoT terminal is sent to the target serving base station in advance.

[0012] In the mobility management method of this application embodiment, the step of triggering the early transmission of the NB-IoT terminal's terminal context to the target serving base station based on the time the NB-IoT terminal leaves the coverage area of ​​the source serving base station includes:

[0013] Determine the first point in time when the NB-IoT terminal leaves the coverage area of ​​the source serving base station;

[0014] At a second time point prior to the first time point, the terminal context of the NB-IoT terminal is sent to the target serving base station in advance; the selection of the second time point satisfies that its time advance relative to the first time point is sufficient for the source serving base station to complete sending the terminal context of the NB-IoT terminal to the target serving base station.

[0015] In the mobility management method of this application embodiment, determining the first time point at which the NB-IoT terminal leaves the coverage area of ​​the source serving base station includes:

[0016] Based on the coverage area planning of the satellites where the source service base station and the target service base station are located, and the location of the NB-IoT terminal, the first time point at which the NB-IoT terminal leaves the coverage area of ​​the source service base station is predicted.

[0017] In the mobility management method of this application embodiment, determining the first time point at which the NB-IoT terminal leaves the coverage area of ​​the source serving base station includes:

[0018] The first time point at which the NB-IoT terminal leaves the coverage area of ​​the source service base station is obtained from the ground operation control center.

[0019] In the mobility management method of this application embodiment, there is no inter-satellite communication link between the source serving base station and the adjacent satellite-based base station. The step of sending the terminal context of the NB-IoT terminal to the adjacent satellite-based base station that can serve as the target serving base station in advance includes:

[0020] In response to receiving the RRC connection establishment complete message sent by the NB-IoT terminal, the terrestrial core network is requested to send the terminal context of the NB-IoT terminal to the target serving base station in advance.

[0021] In the mobility management method of this application embodiment, there is no inter-satellite communication link between the source serving base station and the adjacent satellite-based base station. The step of sending the terminal context of the NB-IoT terminal to the adjacent satellite-based base station that can serve as the target serving base station in advance includes:

[0022] In response to the NB-IoT terminal completing the PDU session establishment with the network side, and confirming that the PDU session supports voice service transmission based on the QoS parameter configuration of at least one QoS stream contained in the PDU session, the terrestrial core network is requested to send the terminal context of the NB-IoT terminal to the target serving base station in advance.

[0023] On the other hand, this application also provides a mobility management device for low-Earth orbit satellites that supports voice via NB-IoT, comprising:

[0024] The terminal context sending module is used to send the terminal context of the NB-IoT terminal to a neighboring satellite base station that can serve as the target service base station in advance, before the serving satellite of the NB-IoT terminal in the connected state changes.

[0025] On the other hand, embodiments of this application also provide a spaceborne base station, which includes:

[0026] At least one processor; and

[0027] At least one memory storing instructions that, when executed individually or jointly by the at least one processor, cause the spaceborne base station to perform the mobility management method described above.

[0028] On the other hand, embodiments of this application also provide a computer storage medium storing instructions thereon, wherein the instructions, when executed individually or jointly by at least one processor of a computer device, cause the computer device to perform the aforementioned mobility management method.

[0029] As can be seen from the technical solutions provided in the embodiments of this application above, in the embodiments of this application, for an NB-IoT terminal in a connected state, the source serving base station can send the terminal context of the NB-IoT terminal to a neighboring satellite base station that can serve as the target serving base station in advance (e.g., before the serving satellite of the NB-IoT terminal changes). Thus, when the NB-IoT terminal experiences a change in serving satellite and sends an RRC reconstruction request to a neighboring satellite base station that can serve as the target serving base station, the neighboring satellite base station no longer needs to request the terminal context of the NB-IoT terminal from the source serving base station (in contrast, according to the RRC reconstruction process described in the existing NB-IoT protocol, the target serving base station sends a message to the source serving base station to request the terminal context after receiving the RRC reconstruction request); thereby improving the speed and success rate of RRC connection reconstruction and reducing the interruption latency of inter-satellite voice services. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0031] Figure 1 This paper illustrates a schematic diagram of an application environment for voice mobility management using an NB-IoT system for low-Earth orbit satellites, as shown in some embodiments of this application.

[0032] Figure 2 A flowchart is shown of a mobility management method for supporting voice using NB-IoT system for low-Earth orbit satellites in some embodiments of this application;

[0033] Figure 3 The flowcharts of a mobility management method for supporting voice using an NB-IoT system for low-Earth orbit satellites, as shown in other embodiments of this application, are illustrated.

[0034] Figure 4 The flowcharts of a mobility management method for supporting voice using an NB-IoT system for low-Earth orbit satellites, as shown in other embodiments of this application, are illustrated.

[0035] Figure 5 The flowcharts of a mobility management method for supporting voice using an NB-IoT system for low-Earth orbit satellites, as shown in other embodiments of this application, are illustrated.

[0036] Figure 6The flowcharts of a mobility management method for supporting voice using an NB-IoT system for low-Earth orbit satellites, as shown in other embodiments of this application, are illustrated.

[0037] Figure 7 The diagram shows a structural block diagram of a spaceborne base station in some embodiments of this application.

[0038] [Explanation of Labels in the Attached Image]

[0039] 10. Source service base station;

[0040] 20. Target serving base station;

[0041] 30. NB-IoT terminals;

[0042] 700, Spaceborne Base Station;

[0043] 710. Processor;

[0044] 720. Memory;

[0045] 730. Program;

[0046] 740. Transceiver;

[0047] 750, Antenna. Detailed Implementation

[0048] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0049] It should be noted that in the embodiments of this application, the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved are all information and data authorized and agreed upon by the user and fully authorized by all parties. That is, the acquisition, transmission, storage, use, and processing of data in the technical solution of this application all comply with the relevant provisions of national laws and regulations.

[0050] In the description of this application, unless otherwise stated, "and / or" is a term describing the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone, where A and B can be singular or plural. Furthermore, in the description of this disclosure, unless otherwise stated, "multiple" refers to two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0051] In this application, the expressions "greater than" or "less than" may be used to determine whether a specific condition is met, but this is only for illustrative purposes and is not intended to exclude statements of "above" or "below". A condition expressed as "above" may be replaced by "greater than", a condition expressed as "below" may be replaced by "less than", and a condition expressed as "above and less than" may be replaced by "greater than and below". Furthermore, hereinafter, "A" to "B" represent at least one of the elements from A (inclusive of A) to B (inclusive of B).

[0052] In the embodiments of this application, the singular forms "a," "the," etc., including the plural forms, should be broadly understood as "a kind" or "a class" rather than limited to the meaning of "an." Furthermore, the term "the" should be understood to include both the singular and plural forms, unless the context explicitly indicates otherwise. Additionally, the term "according to" should be understood as "at least partially based on…," and the term "based on" should be understood as "at least partially based on…," unless the context explicitly indicates otherwise.

[0053] This application provides the method operation steps as described in the embodiments or flowcharts, but based on conventional or non-inventive labor, more or fewer operation steps may be included. The order of steps listed in the embodiments is merely one possible execution order among many steps and does not represent the only execution order. In actual system or device products, the methods shown in the embodiments or drawings can be executed sequentially or in parallel.

[0054] It should be noted that in the embodiments of this application, certain software, components, models and other existing solutions in the industry may be mentioned. These should be regarded as exemplary and are only intended to illustrate the feasibility of implementing the technical solution of this application. However, it does not mean that the applicant has used or necessarily used the solution.

[0055] This application uses terminology used in some communication specifications (such as 3GPP, the European Telecommunications Standards Institute (ETSI), Extensible Radio Access Network (ERAN), and Open-Radio Access Network (O-RAN)) to describe various embodiments, but this is merely illustrative. The various embodiments of this application can also be readily modified and applied in other communication systems.

[0056] In this application, NB-IoT terminal refers to a terminal that can conduct voice services with low-Earth orbit satellites using the NB-IoT system. It can have different forms, such as: general-purpose terminals (e.g., 5G mobile phone terminals) with NB-IoT communication chips installed, and dedicated terminals with NB-IoT communication chips installed.

[0057] To support the service needs of terrestrial narrowband IoT, the first NB-IoT standard was created in Release 13 (Rel-13) of the standard released by the 3rd Generation Partnership Project (3GPP). This standard was based on a lightweighting of the 4G LTE system and added features tailored to narrowband IoT scenarios. When considering its application to terrestrial narrowband IoT, the NB-IoT standard was primarily designed for infrequent small data packets in stationary or low-mobility scenarios. Therefore, based on the actual mobility management requirements of application scenarios, the terrestrial NB-IoT standard does not support mobility management in connected mode (i.e., handover), but only supports mobility management in idle mode (i.e., cell reselection).

[0058] For satellite-based narrowband IoT in non-terrestrial networks (NTNs) implemented by low-Earth orbit satellites, even stationary NB-IoT terminals face the challenge of traversing different cells due to the high-speed movement of satellites. If handover is not supported, the terminal will lose connection and re-establish a connection when the satellite cell covering it changes, resulting in significant service interruption latency. However, considering that mainstream narrowband IoT applications typically do not have strict requirements for service interruption latency, and the desire for NB-IoT NTN to more easily reuse the mature industry chain of NB-IoT terminals for terrestrial IoT, the 3GPP international standardization organization's design standard for NB-IoT NTN still considers initially adopting the provisions of the terrestrial network standard, i.e., supporting only cell reselection and not handover.

[0059] To date, the NB-IoT standard officially released by 3GPP does not support voice services. However, 3GPP is currently discussing using NB-IoT to support voice services in NTN scenarios. According to the latest 3GPP discussions, a standardization project on "using NB-IoT to support satellite voice services" is planned for 3GPP Rel-20, targeting Geostationary Earth Orbit (GEO) satellites. Key technical directions to consider in the standardization process include support for low-bit voice codecs, simplification of signaling for the Session Initialization Protocol (SIP) used by the IP Multimedia Subsystem (IMS), and functional optimization aimed at reducing latency. Of course, for GEO satellites, since the satellites are stationary relative to the ground, there is no need to enhance the mobility management functions in the existing NB-IoT standard.

[0060] Unlike GEO satellite systems, when considering using NB-IoT to support voice services in low-Earth orbit (LEO) satellite systems, it is crucial to consider whether mobility management functions need enhancement. Specifically, if the definition of mobility management functions in the NB-IoT NTN standard for satellite narrowband IoT is adopted, if an NB-IoT terminal experiences a change of serving satellite and its inter-satellite voice service has not yet ended, the NB-IoT terminal will disconnect and reconnect, resulting in a significant service interruption latency. For voice services, unlike narrowband IoT services, users have significantly higher requirements for user experience regarding service interruption latency. Therefore, for LEO satellites, it is necessary to design corresponding enhancement schemes for mobility management functions based on the NB-IoT standard.

[0061] According to existing standards, during RRC connection reconstruction, the terminal starts a timer to attempt RRC connection reconstruction once or multiple times. If the RRC connection reconstruction fails before the timer expires, the terminal enters an idle state. Meanwhile, in the 3GPP Rel-18 standard, for NB-IoT NTN for satellite narrowband IoT, there are attempts to optimize the speed of RRC connection reconstruction by enhancing connected-state measurements. The specific enhancement methods and corresponding optimization effects are described below: In NTN scenarios, connected-state NB-IoT terminals can support triggering neighbor cell measurements based on time or location information. Since NB-IoT NTN does not support handover in connected mode, it would have been possible to prevent connected NB-IoT terminals from supporting neighbor cell measurements. The Rel-18 standard introduced the aforementioned connected-mode measurement enhancement for NB-IoT NTN to consider the following technical benefits: if a connected NB-IoT terminal is triggered to perform neighbor cell measurements before a Radio Link Failure (RLF) occurs (usually before a change in serving satellite), then after the RLF occurs, when the NB-IoT terminal attempts to return to connected mode via RRC connection reconstruction, it can reduce cell selection latency by utilizing the neighbor cell measurement results from before the RLF. This optimization focuses on the terminal's utilization of neighbor cell measurement results. However, for services such as voice and video, which have higher requirements and are more sensitive to service interruption latency, this optimization for narrowband IoT services is insufficient.

[0062] In view of this, for scenarios where NB-IoT is used to support voice services in low-Earth orbit satellite systems, based on the design principle of minimizing modifications to the existing NB-IoT standard, this application proposes a mobility management scheme that can significantly improve the speed and success rate of RRC connection re-establishment. Specifically, the core design idea of ​​the proposed scheme is: for NB-IoT terminals that undergo a change of serving satellite before the end of voice service, the terminal's UE Context is sent in advance to a neighboring satellite-based base station that can serve as the target base station. This increases the probability and speed of the terminal successfully completing RRC connection re-establishment at the target serving base station, thereby reducing the latency of voice service interruption between satellite and ground.

[0063] Figure 1 The diagram illustrates an application environment for voice mobility management using the NB-IoT system on low-Earth orbit satellites, as shown in some embodiments of this application. This application environment includes a source serving base station 10, a target serving base station 20, and an NB-IoT terminal 30. Before the serving satellite of the connected NB-IoT terminal 30 changes, the source serving base station 10 can send the terminal context of the NB-IoT terminal 30 to a neighboring satellite-based base station that can serve as the target serving base station 20. This improves the speed and success rate of RRC connection reconstruction for the NB-IoT terminal 30 and reduces the interruption latency of the NB-IoT terminal 30's inter-satellite voice service when the serving satellite changes.

[0064] In some embodiments of this application, the source serving base station 10 is the satellite base station currently providing services to the NB-IoT terminal 30, and the target serving base station 20 is the next satellite base station to take over providing services to the NB-IoT terminal 30 (generally an adjacent satellite base station of the source serving base station 10). Both the source serving base station 10 and the target serving base station 20 are mounted on corresponding low-Earth orbit satellites.

[0065] This application provides a mobility management method for voice support using an NB-IoT system on low-Earth orbit satellites, which can be applied to the onboard base station side as the source serving base station. (Refer to...) Figure 2 As shown in some embodiments of this application, the mobility management method for low-Earth orbit satellites using the NB-IoT system to support voice may include the following steps:

[0066] Step 201: Before the serving satellite of the NB-IoT terminal in the connected state changes, send the terminal context of the NB-IoT terminal to the adjacent satellite base station that can serve as the target serving base station in advance.

[0067] In this embodiment, for an NB-IoT terminal in a connected state, the source serving base station (i.e., the satellite base station currently providing service to the NB-IoT terminal) can send the terminal context of the NB-IoT terminal in advance (e.g., before the serving satellite of the NB-IoT terminal changes) to a neighboring satellite base station that can serve as the target serving base station (i.e., the next satellite base station to provide service to the NB-IoT terminal). Thus, when the NB-IoT terminal experiences a service satellite change and sends an RRC reconstruction request to a neighboring satellite base station that can serve as the target serving base station, the neighboring satellite base station no longer needs to request the terminal context of the NB-IoT terminal from the source serving base station (in contrast, according to the RRC reconstruction process described in the existing NB-IoT protocol, the target serving base station sends a message to the source serving base station to request the terminal context after receiving the RRC reconstruction request); thereby improving the speed and success rate of RRC connection reconstruction and reducing the interruption latency of inter-satellite voice services.

[0068] In some embodiments of this application, the NB-IoT terminal in the connected state refers to an NB-IoT terminal in the RRC connected state. The RRC connected state refers to the working state after the NB-IoT terminal establishes a complete RRC connection with the base station. In the RRC connected state, data transmission and radio resource management between the NB-IoT terminal and the network can be supported.

[0069] In some embodiments of this application, if there are multiple adjacent satellite-based base stations that can serve as the target serving base station (for example, in the case where the operator has deployed a multi-layer low-Earth orbit constellation that can provide overlapping coverage), since it is uncertain which one the NB-IoT terminal will choose as the target serving base station before the NB-IoT terminal initiates an RRC reconstruction request, the source serving base station can send the terminal context of the NB-IoT terminal to all adjacent satellite-based base stations that can serve as the target serving base station.

[0070] In 5G systems, the terminal context is a set of critical information stored by the base station and core network to manage terminal connections and maintain sessions. It includes the terminal's status, configuration parameters, security information, etc., in the wireless network, ensuring session continuity and Quality of Service (QoS). The main components of the terminal context include UE identification information, Protocol Data Unit (PDU) session information established by the UE, QoS parameters, user plane data radio bearer configuration, mobility management information, RRC status, security context, UE capability information, etc. In the embodiments of this application, during the RRC reconstruction process, the NB-IoT terminal needs to use the terminal context of its neighboring satellite base stations that can serve as target serving base stations.

[0071] In some embodiments of this application, the mobility management scheme proposed in this application can be implemented in different ways depending on whether there is an inter-satellite communication link between adjacent satellites (i.e., whether there is an inter-satellite communication link between the source serving base station and the adjacent satellite base station), as described in detail below.

[0072] I. There is an inter-satellite communication link between the source serving base station and the adjacent satellite-based base station.

[0073] (a) Implementation method of the mobility management scheme proposed in this application 1

[0074] In some embodiments of this application, when an inter-satellite communication link exists between the source serving base station and its neighboring satellite-based base stations, the reporting of neighboring cell measurement results by an NB-IoT terminal in RRC connected state can trigger interaction of terminal context between neighboring satellite-based base stations (i.e., between the source serving base station and its neighboring satellite-based base stations). Specifically, in response to receiving the neighboring cell measurement results reported by the NB-IoT terminal, the source serving base station sends the terminal context of the NB-IoT terminal to the target serving base station in advance. The corresponding specific processing flow can be as follows: Figure 3 As shown.

[0075] refer to Figure 3 As shown, after an NB-IoT terminal enters the connected state, its source serving base station can send an RRC reconfiguration message carrying measurement configuration to the NB-IoT terminal. The measurement configuration mainly includes measurement objects, report configurations, and other parameters; among them, the report configuration can configure or specify the triggering method for reporting measurement results. For example, the A3 event (neighbor cell signal quality is better than a certain threshold of the serving cell) can be configured in the report configuration as the triggering condition for reporting measurement results.

[0076] The NB-IoT terminal can perform measurement configuration based on the received RRC reconfiguration message and return an RRC reconfiguration completion message to the source serving base station. If the NB-IoT terminal detects that a configured "measurement result reporting trigger event" is satisfied based on signal measurements of the serving cell and neighboring cells (e.g., the A3 event is satisfied), it will report the neighboring cell measurement results to the source serving base station. If the source serving base station receives the neighboring cell measurement results reported by the NB-IoT terminal, it triggers the interaction of terminal context between adjacent satellite base stations, that is, it triggers the source serving base station to send the terminal context of the NB-IoT terminal in advance to the adjacent satellite base station that can serve as the target serving base station.

[0077] Unlike existing protocols, in the embodiments of this application, the terminal context of the NB-IoT terminal is not temporarily obtained from the source serving base station only when the neighboring satellite base station that can serve as the target serving base station receives the RRC reconstruction request sent by the NB-IoT terminal; instead, the source serving base station sends the terminal context of the NB-IoT terminal to the neighboring satellite base station that can serve as the target serving base station in advance and proactively before the serving satellite of the NB-IoT terminal changes.

[0078] Based on this, when the NB-IoT terminal leaves the coverage area of ​​the serving cell (i.e., leaves the coverage area of ​​the source serving base station), the NB-IoT terminal will detect a radio link failure. Since the voice service of the NB-IoT terminal may not have been completed at this time, the NB-IoT terminal will attempt to re-establish the RRC connection to return to the RRC connected state. Specifically, the NB-IoT terminal will select the target cell for RRC reconstruction based on the measurement results and send an RRC reconstruction request message to the target cell. In the embodiments of this application, the target cell for RRC reconstruction is a satellite cell formed by a neighboring satellite base station that can serve as the target serving base station.

[0079] (ii) Implementation method of the mobility management scheme proposed in this application 2

[0080] In some embodiments of this application, when an inter-satellite communication link exists between the source serving base station and adjacent satellite-based base stations, the predictable characteristics of satellite trajectories and coverage areas can be utilized to trigger interaction of terminal context between adjacent satellite-based base stations based on time (rather than based on measurement result reporting). That is, the source serving base station can trigger the early transmission of the NB-IoT terminal's terminal context to the target serving base station based on the time the NB-IoT terminal leaves its coverage area. The corresponding specific processing flow can be as follows: Figure 4 As shown.

[0081] refer to Figure 4 As shown, after the NB-IoT terminal enters the connected state, the source serving base station can determine the first time point (referred to as T1 in this document) when the NB-IoT terminal leaves the coverage area of ​​the source serving base station; in addition, a time point before the first time point can be preset (i.e., the second time point, which can also be referred to as T2).

[0082] In some embodiments of this application, determining the time point T1 at which the NB-IoT terminal leaves the coverage area of ​​the source serving base station may include: the source serving base station predicting the time point T1 at which the NB-IoT terminal leaves the coverage area of ​​the source serving base station based on its own and the coverage area planning of the satellites where the target serving base station is located, and the location of the NB-IoT terminal (i.e., Figure 4The central source service base station predicts T1 using orbit information. As described here, since the coverage area planning and corresponding operating orbit of any low-Earth orbit constellation are determined, the time point when the NB-IoT terminal enters or leaves the coverage area of ​​the satellite base station can be predicted based on the orbit information of the satellite base station and the current location of the NB-IoT terminal.

[0083] Although NB-IoT terminals do not implement encryption at the Access Stratum (AS) layer of the protocol due to the low cost of NB-IoT communication chips, thus preventing them from directly reporting their own location information measured by the Global Navigation Satellite System (GNSS) to the base station, the source serving base station can obtain the location of the NB-IoT terminal through the following technical approach that conforms to the latest developments in 3GPP international standards: the NB-IoT terminal reports the GNSS measurement results to the core network through a non-access stratum (NAS) signaling message, and then the core network transmits the information to the source base station at the request of the source base station.

[0084] In other embodiments of this application, determining the time point T1 at which the NB-IoT terminal leaves the coverage area of ​​the source serving base station may further include: the source serving base station obtaining the time point T1 at which the NB-IoT terminal leaves the coverage area of ​​the source serving base station from the ground operation control center. That is, the ground operation control center can predict the time point at which the NB-IoT terminal leaves the coverage area of ​​the source serving base station and then provide it to the source serving base station; this can reduce the processing pressure on the satellite-based base station. In the method described here, the ground operation control center also predicts the time point at which the NB-IoT terminal leaves the coverage area of ​​the source serving base station based on the coverage area planning of the satellites where the source serving base station and the target serving base station are located, as well as the location of the NB-IoT terminal. The satellite coverage area planning is information that the ground operation control center already knows, while the location information of the NB-IoT terminal can be transmitted from the satellite-based base station to the ground gateway station via a feeder link, and then from the ground gateway station to the ground operation control center via a dedicated fiber optic line.

[0085] In some embodiments of this application, the selection of time point T2 satisfies the following condition: its time advance relative to time point T1 is sufficient for the source serving base station to complete sending the terminal context of the NB-IoT terminal to the target serving base station. Based on this, the specific time offset (i.e., time advance) of T2 relative to T1 can be defined by the source serving base station. When T2 arrives, the source serving base station is triggered to send the terminal context of the NB-IoT terminal to the target serving base station in advance. This not only improves the speed and success rate of RRC connection reconstruction and reduces the interruption latency of inter-satellite voice services, but also avoids the NB-IoT terminal performing neighbor cell measurements, reducing the processing complexity on the terminal side and saving signaling overhead caused by configuration and reporting related to neighbor cell measurements.

[0086] Based on this, when the NB-IoT terminal leaves the coverage area of ​​the serving cell (i.e., leaves the coverage area of ​​the source serving base station), the NB-IoT terminal will detect a radio link failure. Since the voice service of the NB-IoT terminal may not have been completed at this time, the NB-IoT terminal will attempt to re-establish the RRC connection to return to the RRC connected state. Specifically, the NB-IoT terminal will select the target cell for RRC reconstruction based on the measurement results and send an RRC reconstruction request message to the target cell. In the embodiments of this application, the target cell for RRC reconstruction is a satellite cell formed by a neighboring satellite base station that can serve as the target serving base station.

[0087] II. There is no inter-satellite communication link between the source serving base station and the adjacent satellite-based base station.

[0088] When there is no inter-satellite communication link between the source serving base station and the adjacent satellite-based base station, the terminal context of the NB-IoT terminal in the connected state can be sent in advance to the adjacent satellite-based base station that can serve as the target serving base station with the help of network elements of the ground core network. In this case, considering the information transmission delay caused by the relay through the ground core network, it is necessary to trigger the interaction of the NB-IoT terminal's terminal context as early as possible.

[0089] (a) Implementation method of the mobility management scheme proposed in this application 3

[0090] In some embodiments of this application, when there is no inter-satellite communication link between the source serving base station and the adjacent satellite-based base station, when the NB-IoT terminal enters the RRC connected state at the satellite-based base station currently providing services to it, the satellite-based base station immediately sends a request to the ground core network, requesting the ground core network to help send the terminal context of the NB-IoT terminal to the adjacent satellite-based base station that can serve as the target serving base station in advance. The corresponding specific processing flow can be as follows: Figure 5 As shown. In Figure 5In this context, the satellite-borne base station currently providing services to the NB-IoT terminal is the source service base station of the NB-IoT terminal.

[0091] refer to Figure 5 As shown, in response to receiving the RRC connection establishment complete message sent by the NB-IoT terminal, the source serving base station will immediately request the ground core network to send the terminal context of the NB-IoT terminal to a neighboring satellite base station that can serve as the target serving base station.

[0092] (ii) Implementation method of the mobility management scheme proposed in this application 4

[0093] In some embodiments of this application, when there is no inter-satellite communication link between the source serving base station and the adjacent satellite-based base station, when the NB-IoT terminal establishes a PDU session with the satellite-based base station currently providing services to it, and the satellite-based base station identifies the existence of voice services based on the QoS parameter configuration of the QoS stream contained in the PDU session, the satellite-based base station immediately sends a request to the ground core network, requesting the ground core network to help send the terminal context of the NB-IoT terminal to the adjacent satellite-based base station that can serve as the target serving base station in advance. The corresponding specific processing flow can be as follows: Figure 6 As shown. In Figure 6 In this context, the satellite-borne base station currently providing services to the NB-IoT terminal is the source service base station of the NB-IoT terminal.

[0094] refer to Figure 6 As shown, after entering the connected state (i.e., after the NB-IoT terminal sends an RRC connection establishment completion message to the source serving base station), it can initiate a PDU session establishment request to the terrestrial core network as needed. The terrestrial core network will then initiate a PDU session resource establishment request to the source serving base station accordingly. Subsequently, the source serving base station will allocate the necessary air interface resources and user plane tunnel resources for the PDU session and send an RRC reconfiguration message to the NB-IoT terminal to instruct it to perform corresponding configurations, thereby effectively supporting the PDU session. Then, after the source serving base station receives the RRC reconfiguration completion message from the NB-IoT terminal, it will return a PDU session resource establishment response to the terrestrial core network. At this point, the NB-IoT terminal and the network side complete the establishment of the PDU session. Based on this, in response to the NB-IoT terminal establishing a PDU session with the network side, the source serving base station confirms whether the services associated with the PDU session include voice services. If the services associated with the PDU session include voice services, it requests the terrestrial core network to send the NB-IoT terminal's terminal context to a neighboring satellite base station that can serve as the target serving base station in advance.

[0095] In some embodiments of this application, the source serving base station can determine whether the services associated with the PDU session include voice services based on the QoS parameter configuration of the QoS flows included in the PDU session currently established between the NB-IoT terminal and the network side. A PDU session can contain one or more QoS flows, each associated with a specific service type (such as voice, text messages, video, etc.). Specifically, QoS parameters may include a 5G QoS Identifier (5QI), Allocation and Retention Priority (ARP), Guaranteed Flow Bit Rate (GFBR), Maximum Flow Bit Rate (MFBR), Maximum Bit Rate (MBR), and QoS Flow Identity (QFI). The QoS parameter configurations for different service types (such as voice, video, text messages, web browsing, etc.) are typically different; therefore, it can be determined whether the services associated with the PDU session include voice services.

[0096] Although the processes or flows described above include multiple operations that occur in a specific order, it should be clearly understood that these processes or flows may include more or fewer operations that may be executed sequentially or in parallel (e.g., using parallel processors or multithreaded environments).

[0097] With the above Figure 2 Corresponding to the mobility management method for voice support using NB-IoT system for low-Earth orbit satellites shown, this application embodiment also provides a mobility management device for voice support using NB-IoT system for low-Earth orbit satellites, which may include a terminal context sending module. This terminal context sending module can be used to send the terminal context of the NB-IoT terminal in advance to a neighboring satellite base station that can serve as the target service base station before the serving satellite of the NB-IoT terminal in the connected state changes.

[0098] This application also provides a spaceborne base station. Figure 7 The diagram shown is a schematic representation of the configuration of a spaceborne base station according to an embodiment of this application. Figure 7 As shown, the spaceborne base station 700 may include a processor 710 (e.g., a central processing unit CPU) and a memory 720; the memory 720 is coupled to the processor 710. The memory 720 can store various types of data; it also stores an information processing program 730, and executes the program 730 under the control of the processor 710.

[0099] For example, processor 710 can be configured to execute a program to implement the mobility management method as described in the previous embodiment. For example, processor 710 can be configured to control the following: before the serving satellite of an NB-IoT terminal in a connected state changes, the terminal context of the NB-IoT terminal is sent in advance to a neighboring satellite base station that can serve as the target serving base station.

[0100] In addition, such as Figure 7 As shown, the spaceborne base station 700 may also include a transceiver 740 and an antenna 750, etc.; the functions of the above components are similar to those in the prior art, and will not be described in detail here. It is worth noting that the spaceborne base station 700 is not necessarily required to include these components. Figure 7 All components shown; in addition, the spaceborne base station 700 may also include Figure 7 For components not shown, please refer to existing technologies.

[0101] For ease of description, the above devices are described separately by function as various units. Of course, in implementing this application, the functions of each unit can be implemented in one or more software and / or hardware.

[0102] This application also provides a computer storage medium storing instructions thereon, wherein the instructions, when executed individually or jointly by at least one processor of a computer device, cause the computer device to perform the mobility management method described above.

[0103] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), computer-readable storage media, and computer program products according to some embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processor to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processor, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0104] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processor to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0105] These computer program instructions may also be loaded onto a computer or other programmable data processor, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable device for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0106] In a typical configuration, a computer device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0107] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0108] Computer-readable media, including both permanent and non-permanent, removable and non-removable media, can store information using any method or technology. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by computer equipment. As defined in this application, computer-readable media does not include transient media, such as modulated data signals and carrier waves.

[0109] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, embodiments of this application can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of this application can take the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0110] The embodiments of this application can be described in the general context of computer-executable instructions, such as program modules, that are executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. The embodiments of this application can also be practiced in distributed computing environments where tasks are performed by remote processors connected via a communication network. In a distributed computing environment, program modules can reside in local and remote computer storage media, including storage devices.

[0111] It should also be understood that, in the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0112] The various embodiments in this application are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0113] In the description of this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this application, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this application, as well as the features of different embodiments or examples.

[0114] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A mobility management method for voice support using a narrowband Internet of Things (NB-IoT) system for low-Earth orbit satellites, applied to the satellite-based base station side as the source serving base station, characterized in that... The method includes: Before the serving satellite of an NB-IoT terminal in a connected state changes, the terminal context of the NB-IoT terminal is sent in advance to a neighboring satellite base station that can serve as the target serving base station.

2. The mobility management method as described in claim 1, characterized in that, The source serving base station and the adjacent satellite-based base station have an inter-satellite communication link. The step of sending the terminal context of the NB-IoT terminal in advance to the adjacent satellite-based base station that can serve as the target serving base station includes: Based on the neighbor cell measurement results of the NB-IoT terminal, the terminal context of the NB-IoT terminal is sent to the target serving base station in advance.

3. The mobility management method as described in claim 2, characterized in that, The step of triggering the early transmission of the NB-IoT terminal's terminal context to the target serving base station based on the neighbor cell measurement results of the NB-IoT terminal includes: In response to receiving the neighbor cell measurement results reported by the NB-IoT terminal, the terminal context of the NB-IoT terminal is sent to the target serving base station in advance.

4. The mobility management method as described in claim 1, characterized in that, The source serving base station and the adjacent satellite-based base station have an inter-satellite communication link. The step of sending the terminal context of the NB-IoT terminal in advance to the adjacent satellite-based base station that can serve as the target serving base station includes: Based on the time it takes for the NB-IoT terminal to leave the coverage area of ​​the source serving base station, the terminal context of the NB-IoT terminal is sent to the target serving base station in advance.

5. The mobility management method as described in claim 4, characterized in that, The step of triggering the early transmission of the NB-IoT terminal's terminal context to the target serving base station based on the time the NB-IoT terminal leaves the coverage area of ​​the source serving base station includes: Determine the first point in time when the NB-IoT terminal leaves the coverage area of ​​the source serving base station; At a second time point prior to the first time point, the terminal context of the NB-IoT terminal is sent to the target serving base station in advance; the selection of the second time point satisfies that its time advance relative to the first time point is sufficient for the source serving base station to complete sending the terminal context of the NB-IoT terminal to the target serving base station.

6. The mobility management method as described in claim 5, characterized in that, The determination of the first time point at which the NB-IoT terminal leaves the coverage area of ​​the source serving base station includes: Based on the coverage area planning of the satellites where the source service base station and the target service base station are located, and the location of the NB-IoT terminal, the first time point at which the NB-IoT terminal leaves the coverage area of ​​the source service base station is predicted.

7. The mobility management method as described in claim 5, characterized in that, The determination of the first time point at which the NB-IoT terminal leaves the coverage area of ​​the source serving base station includes: The first time point at which the NB-IoT terminal leaves the coverage area of ​​the source service base station is obtained from the ground operation control center.

8. The mobility management method as described in claim 1, characterized in that, There is no inter-satellite communication link between the source serving base station and the adjacent satellite-based base station. The step of sending the terminal context of the NB-IoT terminal in advance to the adjacent satellite-based base station that can serve as the target serving base station includes: In response to receiving the Radio Resource Control (RRC) connection establishment complete message sent by the NB-IoT terminal, the system requests the terrestrial core network to send the terminal context of the NB-IoT terminal to the target serving base station in advance.

9. The mobility management method as described in claim 1, characterized in that, There is no inter-satellite communication link between the source serving base station and the adjacent satellite-based base station. The step of sending the terminal context of the NB-IoT terminal in advance to the adjacent satellite-based base station that can serve as the target serving base station includes: In response to the NB-IoT terminal completing the establishment of a Protocol Data Unit (PDU) session with the network side, and confirming that the PDU session supports voice service transmission based on the QoS parameter configuration of at least one Quality of Service (QoS) stream contained in the PDU session, the terrestrial core network is requested to send the terminal context of the NB-IoT terminal to the target serving base station in advance.

10. A mobility management device supporting voice via NB-IoT for low-Earth orbit satellites, characterized in that, include: The terminal context sending module is used to send the terminal context of the NB-IoT terminal to a neighboring satellite base station that can serve as the target service base station in advance, before the serving satellite of the NB-IoT terminal in the connected state changes.

11. A spaceborne base station, characterized in that, include: At least one processor; as well as At least one memory storing instructions that, when executed individually or jointly by the at least one processor, cause the spaceborne base station to perform the method according to any one of claims 1 to 9.

12. A computer storage medium storing instructions thereon, characterized in that, When the instructions are executed individually or jointly by at least one processor of a computer device, the computer device performs the method according to any one of claims 1 to 9.

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