WO2025086169A1

WO2025086169A1 - Satellite access method and system

Info

Publication number: WO2025086169A1
Application number: PCT/CN2023/126552
Authority: WO
Inventors: Ahmed MOHAMMED MIKAEIL SALIH
Original assignee: Shenzhen TCL New Technology Co Ltd
Current assignee: Shenzhen TCL New Technology Co Ltd
Priority date: 2023-10-25
Filing date: 2023-10-25
Publication date: 2025-05-01
Anticipated expiration: 2026-04-25

Abstract

A satellite access method is disclosed. A first on-board satellite radio access node receives a signaling message from a user equipments (UE) in a group of UEs. The signaling message shows a change of a serving on-board satellite radio access node of the group of UEs. The first on-board satellite radio access node forwards the signaling message to an on-ground network node to trigger handover of the group of UEs from the first on-board satellite radio access node to a second on-board satellite radio access node. The handover of the group of UEs is based on per-UE-group signaling including: a request message that requests the second on-board satellite radio access node to establish, modification, or release bear context for the group of UEs or to establish, modification, or release resources for sessions associated with the group of UEs.

Description

SATELLITE ACCESS METHOD AND SYSTEM

BACKGROUND OF DISCLOSURE

1. Field of Disclosure

The present disclosure relates to the field of communication systems, and more particularly, to a satellite access method and system.

2. Description of Related Art

Non-Terrestrial Network (NTN) can extend the reach of 5G New Radio (NR) to remote and rural areas, as well as maritime and airborne domains, where terrestrial networks are not feasible or cost-effective.

NTN can improve the reliability and resilience of 5G NR by providing backup or alternative links in case of terrestrial network failures or congestion. Additionally, NTN can enable new business opportunities and innovation for 5G service providers, network operators, satellite operators, and end users, by creating a converged and integrated network environment.

Technical Problem

According to current standardization progress (i.e., 3GPP RAN#101 and SA#101 meetings for release 19) , there is a direction to study NTN regenerative payload generic architecture in which the satellite gNB is to be delivered onboard of satellite. In this architecture, when a gNB or a gNB-DU is located on board satellites, and the satellite constellation is continuously moving, the ground station (GS) must locate a new on-board gNB-CU/DU approximately every couple of minutes (for example, around 7-8 minutes for the LEO category) in order to facilitate UEs'handovers.

For the scenario where the gNB-DU is deployed on-board, when satellite constellations move, the on-board gNB-DU/CU that serves the UEs will move away from the corresponding on-ground gNB-CU or UPF. This situation necessitates the implementation of a new type of update for F1/NG-U tunnels, either on a per-group of UEs basis or per gNB-DU/CU basis. Moreover, this scenario can lead to the need for modifications in PDU/multicast/broadcast sessions or contexts and handovers. However, the existing 5G NR protocols do not currently provide support for signaling related to the modification of PDU/multicast/broadcast sessions or contexts on a per-group-of-UEs basis, nor do they facilitate signaling for handovers involving a group of UEs.

Additionally, when the on-board gNB-DU/CU node that serves UEs is changed, all UE or the majority of UEs under the coverage of the on-board gNB-DU/CU node must be handed over simultaneously to a new node. This type of handover will result in significant signaling overhead over the F1-C and NG-C control plane interfaces that connect the on-board and on-ground network nodes. This is especially true for the signaling of the current 5G NR protocol, which was primarily designed for single UE signaling, for tasks such as PDU/multicast/broadcast session context modifications, and/or handover signaling.

SUMMARY

An object of the present disclosure is to propose a satellite access method and system.

In a first aspect, an embodiment of the invention provides satellite access method, comprising:

sending a signaling message indication from user equipments (UEs) to a first on-board satellite radio access node and/or an on-ground network node, wherein the signaling message indication indicates a change of a serving on-board satellite radio access node;

grouping the UEs into different groups of UEs by the first on-board satellite radio access node and/or the on-ground network node based on the signaling message indication from the UEs; and

triggering by the first on-board satellite radio access node and/or the on-ground network node a handover of at least one of the groups of UEs from the first on-board satellite radio access node to a second on-board satellite radio access node, wherein the handover of at least one of the groups of UEs is based on the signaling message indication from the UEs and/or a per-UE-group signaling message provided by the first on-board satellite radio access node and/or the on-ground network node.

In a second aspect, an embodiment of the invention provides a network system comprising:

user equipments (UEs) ;

a first on-board satellite radio access node; and

an on-ground network node;

wherein the user equipments (UEs) are configured to send a signaling message indication to the first on-board satellite radio access node and/or the on-ground network node, wherein the signaling message indication indicates a change of a serving on-board satellite radio access node;

the first on-board satellite radio access node and/or the on-ground network node is configured to group the UEs into different groups of UEs based on the signaling message indication from the UEs;

the first on-board satellite radio access node and/or the on-ground network node is configured to trigger a handover of at least one of the groups of UEs from the first on-board satellite radio access node to a second on-board satellite radio access node; and

the handover of at least one of the groups of UEs is based on the signaling message indication from the UEs and/or a per-UE-group signaling message provided by the first on-board satellite radio access node and/or the on-ground network node.

In a third aspect, an embodiment of the invention provides a base station comprising a processor configured to call and run a computer program stored in a memory, to cause a device in which the processor is installed to execute the disclosed method.

The disclosed method may be programmed as computer executable instructions stored in non-transitory computer readable medium. The non-transitory computer readable medium, when loaded to a computer, directs a processor of the computer to execute the disclosed method.

The non-transitory computer readable medium may comprise at least one from a group consisting of: a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a Read Only Memory, a Programmable Read Only Memory, an Erasable Programmable Read Only Memory, EPROM, an Electrically Erasable Programmable Read Only Memory and a Flash memory.

The disclosed method may be programmed as a computer program product, that causes a computer to execute the disclosed method.

The disclosed method may be programmed as a computer program, that causes a computer to execute the disclosed method.

Advantageous Effects

The disclosure provides a method for supporting satellite access with on-board radio access node functionality. The benefits and innovation aspects of the disclosure include:

This disclosure introduces new signaling and procedures related to per-UE-group session or context management and handovers. These enhancements aim to mitigate the signaling overload issues within the F1-C and NG-C control plane interface.

The disclosure further introduces a new set of signaling, indications, and triggers designed to realize per- UE-group session or context management and handover signaling, particularly in scenarios where the access node is located on board a satellite.

BRIEF DESCRIPTION OF DRAWINGS

In order to more clearly illustrate the embodiments of the present disclosure or related art, the following figures will be described in the embodiments are briefly introduced. It is obvious that the drawings are merely some embodiments of the present disclosure, a person having ordinary skill in this field may obtain other figures according to these figures without paying the premise.

FIG. 1 illustrates a schematic view showing a network system with satellite enabled NR-RAN.

FIG. 2 illustrates a schematic view showing a network system with UE groups.

FIG. 3 illustrates a schematic view showing an embodiment of a satellite access method.

FIG. 4 illustrates a schematic view showing signaling for a handover triggered by a satellite change or moving of an on-board radio access node.

FIG. 5 illustrates a schematic view showing an embodiment of a network system with partially on-board Radio access nodes.

FIG. 6 illustrates a schematic view showing signaling for a handover triggered by moving of a partially on-board radio access node.

FIG. 7 illustrates a schematic view showing an embodiment of a network system with fully on-board Radio access nodes.

FIG. 8 illustrates a schematic view showing signaling for a handover triggered by moving of a fully on-board radio access node.

FIG. 9 illustrates a schematic view showing a user equipment (UE) .

FIG. 10 illustrates a schematic view showing a network node.

FIG. 11 illustrates a schematic view showing a chip or executing the disclosed method in a UE.

FIG. 12 illustrates a schematic view showing a chip or executing the disclosed method in a network node.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the disclosure are described in detail with the technical matters, structural features, achieved objects, and effects with reference to the accompanying drawings as follows. Specifically, the terminologies in the embodiments of the present disclosure are merely for describing the purpose of the certain embodiment, but not to limit the disclosure.

Abbreviations used in the description are listed in the following:

Table 1

In the description, a node installed on board a satellite can be briefly referred to as an on-board node. Thus, a gNB installed on board a satellite can be briefly referred to as an on-board gNB. Similarly, a gNB-DU installed on board a satellite can be briefly referred to as an on-board gNB-DU.

This disclosure introduces new signaling and procedures for PDU/multicast/broadcast session or context modification/update/release and/or handover to handle signaling overload issues in F1-C and NG-C control plane interface. Additionally, the disclosure also introduces new set of signaling and triggers to assist realizing the per-UE-group session or context modification/update/release and/or per-UE-group handover procedures, especially in scenarios where the access node is located on board a satellite.

The development of 5G service via satellite constellation has been undertaken collaboratively within both the 3GPP Radio Access Network (RAN) and System Architecture (SA) groups. Currently, there is a direction to study NTN support of regenerative payload architecture in both RAN and SA working groups.

The transparent satellite access network composed of satellite payload implements frequency conversion and a radio frequency amplifier in both uplink and downlink direction. A satellite operates as an analogue RF repeater that repeats the NR-Uu radio interface from the feeder link (between the NTN gateway and the satellite) to the service link (between the satellite and the UE) and vice versa. The Satellite Radio Interface (SRI) used on the feeder link is the NR-Uu. In other words, the satellite does not terminate NR-Uu it just repeats it. Different transparent satellites may be connected to the same gNB on the ground.

As for the case of regenerative satellite access, the satellite may have some functions of 5GS. One implementation is when the satellite payload may implement a full gNB supporting a satellite enabled NR-RAN or a gNB-DU deployed on-board shown in FIG. 1. A satellite radio interface (SRI) transports the N1 (NAS) /N2 (NG-C) /N3 (NG-U) interfaces between the on-ground 5G CN and the on-board gNB-CU.

With reference to FIG. 1, a core network (CN) 300 is connected to an on-ground network 200 of radio access network (RAN) . The CN 300 may include LTE CN or 5GC which may include a user plane function (UPF) 30b, session management function (SMF) 30d, access and mobility management function (AMF) 30c. The CN 300 may further comprise other network functions, such as unified data management (UDM) , policy control function (PCF) , control plane (CP) /user plane (UP) separation (CUPS) , authentication server (AUSF) , network slice selection function (NSSF) , and the network exposure function (NEF) .

The UPF 30b is connected to a data network (DN) 40. The AMF 30c is connected to a gNB-CU 20-1c through interfaces N1 and N2. The gNB-CU 20-1c is connected to an on-board gNB-DU 20-2c. An on-board gNB 20b may connect to the on-ground network 200 through an on-ground gateway. The on-ground network 200 may comprise other base station, such as gNB 20d. For example, UE 10a and UE 10b are in coverage of the on-board gNB 20b. The UE 10b is in coverage of the gNB 20d.

FIG. 2 show a satellite wireless system for providing a multicast, broadcast and/or a unicast service to a plurality of wireless devices or UEs, such as UE 10a-10g, according to a method of the present disclosure. The UEs, such as UE 10a-10g, are connected to one or more satellite radio access nodes, such as a first on-board satellite radio access node 201 and a second on-board satellite radio access node 202, via first radio interface (Uu) . A single satellite radio access node may comprise two interconnected nodes through a user plane internal network interface (F1-U) and a first control plane internal network interface (F1-C) . One of these nodes can be deployed on board a satellite, while the other is situated on the ground. At least one of the satellite radio access nodes is connected to a user plane function (UPF) via NG-U interface and to an access and mobility management function (AMF) via a second control plane internal network interface NG-C. The use plane function is connected to a data network (DN) 40 to provide the respective multicast, broadcast and/or a unicast service to the UEs.

In the wireless system, as satellite constellations move, the on-board satellite radio access nodes providing coverage for UEs will rotate away from the corresponding on-ground network node. New on-board satellite radio access nodes will then take over or share coverage for the UEs. As illustrated in FIG. 2, this situation results in three types of UE coverage:

1. UEs (e.g., UE 10a, 10b, and 10c) in group 1 are under coverage of the old/source on-board satellite radio access nodes.

2. UEs (e.g., UE 10d and 10e) in group 2 are within the overlapping coverage area of both the old/source and the new/target on-board satellite radio access nodes.

3. UEs (e.g., UE 10f and 10g) in group 3 are under coverage of the new/target on-board satellite radio access nodes.

To ensure the efficient utilization of the F1-U and NG-U user plane interfaces, it is imperative to transition UEs in group 2 and ideally group 2 and 3 to the F1-U and NG-U user plane interfaces connected with the new/target on-board satellite radio access nodes. However, moving such group of UEs simultaneously to a new interface will require significantly a large amount of signaling messages over the F1-C and NG-C control plane interfaces that connect the on-board and on-ground network nodes. This is especially true for the signaling of the current 5G NR protocol, which was primarily designed for single UE signaling, for tasks such as PDU/multicast/broadcast session context modifications, and/or handover signaling. The following section introduces new per-UE-group session or context management e.g., UE F1/NG-U tunnels management, PDU/multicast/broadcast session or context modification/update/release and/or handover related signaling and procedures to handle the signaling overload issues in F1-C and NG-C control plane interface. Additionally, the section also introduces new set of signaling, indication, and triggers to assist realizing the per-UE-group session or context modification/update/release and/or per-UE-group handover to handle the scenario where access node is onboard of satellite.

This disclosure proposes a method to address the challenges associated with session management, mobility/handover, bearers change, and node reselection for efficient fronthaul or backhaul traffic routing. It also covers load balancing, QoS guarantee, and coverage guarantee for a wireless device that receives unicast, multicast, or broadcast sessions or services over a converged wireless network, which includes terrestrial and satellite radio access. The method include:

(1) . A set of control plane signaling, triggers, and indications from a wireless device and/or an on-board satellite or on-ground network node to the on-ground control node (e.g., gNB-CU/AMF) to help efficient PDU/multicast/broadcast context modification and/or handover related signaling for the scenario when satellite radio access node is deployed onboard a satellite.

(2) . A new system and procedure with group-based triggers and signaling to handle data forwarding for groups of user equipment (UEs) when the on-board satellite node changes, or during handovers and session/context updates. This system is designed to ensure requirements are met for scenarios involving a moving satellite radio access node, while also addressing signaling overload issues and optimizing fronthaul/backhaul traffic routing and load balancing.

The detailed description of method is given in the section below.

Amethod for supporting satellite access with on-board radio access nodes and/or on-ground-based access is introduced FIG. 4, in which the on-board satellite radio access nodes are in a frequent movement due to continuous movements of satellite constellation, leading to different groups of UEs in different coverage types:

1. UEs in group 1 are under coverage of the old on-board satellite radio access nodes.

2. UEs in group 2 are within the overlapping coverage area of both the old and the new on-board satellite radio access nodes.

3. UEs in group 3 are under coverage of the new on-board satellite radio access nodes.

In at least one embodiment of the disclosure, a wireless device (or UE) in a group of UEs transmits a signaling message, either periodically or as determined by pre-configured parameters from the network, such as UE location or satellite ephemeris data, to a first on-board satellite radio access node 201 (e.g., an old/source on-board satellite radio access node) which currently serves the UEs. The signaling message can be an access stratum (AS) message or a non-access stratum (NAS) message indicating explicitly or implicitly a change of the serving on-board satellite radio access node of the wireless device (or UE) to assist the network in efficient mobility and resources management. The signaling message may include at least one of the following: coverage group type change, reference location change, reference time change, coverage or measurement change, frequency change, physical cell identity change, satellite access related SIB change, satellite ID change, UE session access type change or other associated information.

Upon the reception of the signaling message from UEs, the first on-board satellite radio access node 201 (e.g., an old/source on-board satellite radio access node) may group UEs into UE-groups based on the signaling into a different group, and then may forward the signaling message to the on-ground network node (e.g., an on-ground radio access node and/or on-ground network control plane node) via the first or second control plane internal network interface based on one or more of: information within the message, coverage group type, and other related information of the UEs.

The on-ground network node (e.g., an on-ground radio access node and/or on-ground network node) may use per-UE-group signaling of Uu/NG/XnAP/F1AP/E1AP messages associated with the group of UEs over the associated logical Uu/NG/Xn/F1/E1 interfaces. These messages include one or more of the following messages:

A. Handover related signaling between the on-ground network node and the first on-board satellite radio access node 201 (e.g., an old/source on-board satellite radio access node) . For example, the handover related signaling may comprise one or more of an indication of a handover, a handover command, and handover required information for the session context and/or bearer context associated with the group of UEs to the first on-board satellite radio access node 201 (e.g., an old/source on-board satellite radio access node) .

B. Inter on-board satellite radio access node handover signaling between the first and the second on-board satellite radio access node 202. For example, the inter on-board satellite radio access node handover signaling may comprise exchange of handover request and response messages for establishing/modification/releasing of the session context and/or bearer context associated with the group of UEs as indicated through the control plane internal network interface.

C. Handover configuration related signaling between the first on-board satellite radio access node 201 and the group of UEs. For example, the handover related signaling may comprise a group-based RRC message scrambled with a group RNTI, which is sent to the group of UEs indicated in the handover request. For example, the group-based RRC message comprises a per-UE-group RRC Reconfiguration message scrambled with a group-based RNTI to indicates when to stop the data transmission for the group of UEs that have indicated a change on the on-board access type, and to provide the access related configuration information of the second on-board satellite radio access node 202 (e.g., a new/target on-board satellite radio access node) .

D. Path switching related signaling between the second on-board satellite radio access node 202 (e.g., a new/target on-board satellite radio access node) and the on-ground network node. For example, the path switching related signaling may comprise a path switch request and acknowledgement of the path switch request for the session context and/or bearer context associated with the group of UEs as indicated within the first control plane internal network interface.

E. Core network session update related signaling between the on-ground network node and a network entity (e.g., the data network (DN) 40 or the control plane function (UPF) node 30b) to switch the NG-U/tunnel user plane for session context and/or bearer context associated with the group of UEs provided in the first control plane internal network interface between peer NG/Xn/F1/E1 nodes.

In some embodiment of the disclosure, the on-ground network node may be an AMF (e.g., the AMF 30c) , a gNB-CU, and/or a gNB. The first on-board satellite radio access node 201 (e.g., an old/source on-board satellite radio access node) may be a fully on-board gNB, a gNB-CU, or a gNB-DU. The second on-board satellite radio access node 202 (e.g., a new/target on-board satellite radio access node) may be a fully on-board gNB, a gNB-CU, or a gNB-DU. Embodiments of the disclosure may be applied to the scenarios in the following.

Partially on-board radio access node scenario: In the scenario, a part (e.g., gNB-DU) of a radio access node is deployed onboard of a satellite and another part (e.g., gNB-CU) of the radio access node is deployed on the ground.

Fully on-board radio access node scenario: In this scenario, one radio access node is completely integrated on the satellite.

With reference to FIG. 3, a satellite access method is executed in the network system. User equipments (UEs) sends a signaling message indication from to a first on-board satellite radio access node 201 and/or an on- ground network node (A001) . The signaling message indication indicates a change of a serving on-board satellite radio access node. The first on-board satellite radio access node 201 receives the signaling message from the user equipments (UE) in a group of UEs.

The first on-board satellite radio access node 201 and/or the on-ground network node groups the UEs into different groups of UEs b based on the signaling message indication from the UE (A002) .

The first on-board satellite radio access node 201 and/or the on-ground network node triggers a handover of at least one of the groups of UEs from the first on-board satellite radio access node 201 to a second on-board satellite radio access node 202, wherein the handover of at least one of the groups of UEs is based on the signaling message indication from the UEs and/or a per-UE-group signaling message provided by the first on-board satellite radio access node 201 and/or the on-ground network node (A003) . These operations, A001, A002, and A003, can take place independently, sequentially, or in combination with one another.

In some embodiments of the disclosure, the on-ground network node, the first on-board satellite radio access node 201, and/or the second on-board satellite radio access node 202 initiates per-UE-group establishment, addition, modification, and/or releasing of the bearer context and/or session resources associated with the at least one of groups of UEs.

In some embodiments of the disclosure, the first on-board satellite radio access node 201 sends a per-UE-group handover signaling to the at least one of the groups of UEs indicating the handover to the second on-board satellite radio access node 202.

In some embodiments of the disclosure, the on-ground network node is an access and mobility management function (AMF) and/or a centralized unit of a base station (gNB-CU) .

In some embodiments of the disclosure, the per-UE-group signaling message is a message provided from on-board satellite radio access node to the on-ground network node.

In some embodiments of the disclosure, the signaling message indication from the UEs is a non-access stratum (NAS) message provided from the UEs to the on-ground network node, wherein the signaling message indication is a pre-configured parameters which comprises UE location or satellite ephemeris data. In some embodiments of the disclosure, the NAS message conveys join, modification, or update of a PDU, multicast, or broadcast session and an indication of access type change of the at least one of the groups of UEs.

In some embodiments of the disclosure, the signaling message indication from the UEs is a radio resource control (RRC) configuration message.

In some embodiments of the disclosure, the signaling message indication and/or the per-UE-group signaling message includes at least one of: coverage group type change, reference location change, reference time change, coverage and/or measurement change, frequency change, physical cell identity change, satellite access related SIB change, satellite ID change, UE session access type change and/or other associated information.

In some embodiments of the disclosure, the signaling message indication and/or the per-UE-group signaling message includes one or more of:

a measurement of one or both of the first and second on-board satellite radio access node 202;

an indication of physical cell identity (PCI) of one or both of the first and second on-board satellite radio access node 202; and

an indication indicating that the serving on-board satellite radio access node of the UEs is changed.

In some embodiments of the disclosure, the sessions associated with the at least one of the groups of UEs comprise protocol data unit (PDU) sessions or multimedia broadcast/multicast service (MBS) sessions.

In some embodiments of the disclosure, the method further comprises sending, from the first on-board satellite radio access node 201, a group-based radio resource control (RRC) message scrambled with a group radio network temporary identifier (RNTI) to the at least one of the groups of UEs.

In some embodiments of the disclosure, the group-based RRC message comprises a per-UE-group RRC reconfiguration message scrambled with a group-based RNTI to indicates when to stop data transmission for the at least one of the groups of UEs that have indicated a change on on-board access type, and/or to provide access related configuration information of the second on-board satellite radio access node 202.

In some embodiments of the disclosure, the method further comprises the second on-board satellite radio access node 202 transmitting a path switching request to the on-ground network node to request path switching for the bears context or the sessions for the at least one of the groups of UEs.

In some embodiments of the disclosure, the first on-board satellite radio access node 201 comprises a first on-board distributed unit of a base station;

the second on-board satellite radio access node 202 comprises a second on-board distributed unit of the base station;

and

the on-ground network node comprises an on-ground centralized unit of the base station.

In some embodiments of the disclosure, the first on-board distributed unit sends a single uplink (UL) RRC message transfer message to the on-ground centralized unit of the base station, the UL RRC message transfer message comprises all bearer contexts associated with the at least one of the groups of UEs that indicate a change on on-board access type.

In some embodiments of the disclosure, the on-ground centralized unit of the base station sends a per-UE-group context setup request message to the second on-board distributed unit of the base station to create bearer context associated with the at least one of the groups of UEs that indicate a change on the on-board access type and establish related data bearers for the at least one of the groups of UEs; and

the second on-board distributed unit of the base station responds to the on-ground centralized unit of the base station a per-UE-group context setup response message.

In some embodiments of the disclosure, the on-ground centralized unit of the base station sends a per-UE-group Context modification request message to the first on-board distributed unit;

the per-UE-group context modification request message includes a per-UE-group RRC reconfiguration message scrambled with a group-based RNTI;

the per-UE-group RRC Reconfiguration message is used to indicates when to stop data transmission for the at least one of the groups of UEs that indicate a change on the on-board access type, and/or to provide access related configuration information of the second on-board distributed unit of the base station; and

the first on-board distributed unit forwards the received per-UE-group scrambled RRC Reconfiguration message to the at least one of the groups of UEs according to an indication of on-board access type change of at least one of the groups of UEs and responds to the on-ground centralized unit of the base station with a per-UE-group context modification response message.

In some embodiments of the disclosure, the access related configuration information of the second on-board distributed unit of the base station comprises one or more of: a second gNB-DU ID, cell IDs, a new group-based RNTI, a second gNB security algorithm identifiers for a selected security algorithms, and/or a random access channel (RACH) resources, association between RACH resources and one or more synchronization signal blocks (SSBs) , association between RACH resources and one or more UE-specific channel state information (CSI) -reference signal (RS) configurations, common RACH resources, and/or system information of a second cell.

In some embodiments of the disclosure, the UEs in the at least one of the groups of UEs responds to the second on-board distributed unit of the base station with an RRC reconfiguration complete message; and the second on-board distributed unit of the base station sends an UL RRC message transfer message to the on-ground centralized unit of the base station to convey the received RRC reconfiguration complete message.

In some embodiments of the disclosure, the on-ground centralized unit of the base station sends a per-UE-group context release command message to the first on-board distributed unit to release the at least one of the groups of UEs that indicate a change on the on-board access type; and

the first on-board distributed unit releases the bearer context associated with the at least one of the groups of UEs that indicate a change on the on-board access type and responds the on-ground centralized unit of the base station with a UE context release complete message.

In some embodiments of the disclosure, the first on-board satellite radio access node 201 comprises a first on-board base station;

the second on-board satellite radio access node 202 comprises a second on-board base station; and

the on-ground network node comprises an access and mobility management function (AMF) .

In some embodiments of the disclosure, the first on-board base station triggers a handover request toward the second on-board base station node to initiate a group-based setup, modification, release of resources for the PDU and/or MBS sessions associated with the at least one of the groups of UEs that indicate a change on an on-board access type;

the second on-board base station responds the handover request from the first on-board base station by establishing, modifying, or requesting releasing resources for the PDU and/or MBS sessions context associated with the at least one of the groups of UEs indicated in the handover request provided from the first on-board base station; and

based on response from the second on-board base station, the first on-board base station triggers a Uu handover by sending a group-based RRC message scrambled with a group RNTI to the at least one of the groups of UEs indicated in the handover request.

In some embodiments of the disclosure, the second on-board base station triggers a N2 path switch request toward the AMF to inform the AMF that the at least one of the groups of UEs have moved to a cell of the second on-board base station, the N2 path switch request includes a list of PDU/MBS sessions to be switched for the at least one of the groups of UEs indicated in the handover request.

In some embodiments of the disclosure, the scrambled group-based RRC message comprises one or more of:

a second gNB cell ID, a new C-RNTI (Cell-RNTI) , second gNB security algorithm identifiers for selected security algorithms and/or dedicated random access channel (RACH) resources, association between RACH resources and one or more synchronization signal blocks (SSBs) , association between RACH resources and one or more UE-specific channel state information (CSI) -reference signal (RS) configurations, common RACH resources, and/or system information of a second cell.

In some embodiments of the disclosure, the AMF send an update SM context request to a session management function (SMF) to request the SMF to update session management (SM) context for the respective PDU/MBS sessions of the at least one of the groups of UEs;

the update SM context request includes lists of PDU/MBS sessions related to the at least one of the groups of UEs indicated in the N2 path switch request;

for the lists of PDU/MBS sessions related to the at least one of the groups of UEs indicated in the N2 path switch request, the SMF sends an N4 Session Modification Request message to a user plane function (UPF) ;

the UPF switches a path for PDU/MBS sessions related to the at least one of the groups of UEs indicated in the N2 path switch request to the second on-board base station and returns an N4 session modification response message to the SMF indicating that the path of PDU/MBS sessions related to the at least one of the groups of UEs indicated in the N2 path switch request are switched; and

the SMF sends an update SM context response to the AMF indicating the PDU/MBS sessions related to the at least one of the groups of UEs which have been switched successfully.

In some embodiments of the disclosure, the AMF sends a path switch request acknowledgment to the second on-board base station indicating that the lists of PDU/MBS sessions related to the at least one of the groups of UEs indicated in the N2 path switch request were successfully switched to a new N3 interface that connects the second on-board base station to a core network; and

based on path switch request acknowledgment from AMF, the second on-board base station confirms success of the handover by sending to the first on-board base station a request to release resources of the PDU/MBS sessions associated with the at least one of the groups of UEs which have been successfully switched or handed-over.

Partially on-board radio access nodes:

Embodiments of the disclosure may be applied to the scenario where a part of a radio access node is deployed onboard of a satellite. For example, a gNB central unit (gNB-CU) is deployed on the ground while gNB distributed units (gNB-DUs) onboard. The gNB-CU and gNB-DUs are connected via multiple F1-C/F1-U interfaces. The gNB-CU on the ground could be connected to another gNB-CU via E1 interface.

In this particular scenario, when satellite constellations shift, the gNB-DU will move from the associated gNB-CU. This leads to a frequent update of F1 tunnels, modifications in UE/multicast/broadcast bearers or contexts, and potential signaling for gNB-DU handovers for each individual UE connection.

To resolve this issue, the on-board gNB-DU and/or the on-ground gNB-CU may group UEs based on the indication message, coverage group type, and/or other related information from the group of UEs and implement the per-UE-groups modifications of PDU/multicast/broadcast bearers and contexts and/or gNB-DU handover signaling. As shown in the example of FIG. 5, UEs 10a-10c are grouped into group 1. UEs 10d-10e are grouped into group 2. UEs 10f-10g are grouped into group 3.

With reference to FIG. 6, signaling between entities in the network system is detailed in the following. Examples of UEs 10 may include UE 10a-10g.

UEs are configured by the first on-board satellite radio access node 201 (e.g., an old/source on-board satellite radio access node) to send RRC signaling to report one or more instances of:

(1) . a measurement of one or both of the first and second on-board satellite radio access node 202;

(2) . an indication of physical cell identity (PCI) of one or both of the first and second on-board satellite radio access node 202; and

(3) . an indication showing that the serving on-board satellite radio access node of the UEs is changed.

UEs located in the overlap area between the first and second on-board satellite radio access node 202 or UEs capable of receiving the new satellite-related access system information block (SIB) can generate the report. Examples of the indication showing the PCIs or showing the change of the serving on-board satellite radio access node are provided in the following Table 2. The SIB change indication reported by UE in the group 2 indicates a change of the serving on-board satellite radio access node by conveying two PCI, i.e., [PCI, PCI2] .

Table 2

Alternatively, the UEs may decide to send non-access stratum (NAS) signaling to the AMF 30c based on pre-configured parameters from the network, such as UE location or satellite ephemeris data. For example, the NAS signaling conveys join, modification, or update of a PDU, multicast, or broadcast session and an indication of access type change of the group of UEs. With reference to TS 29.502, an access type change indicates that the access type of PDU, multicast, or broadcast sessions is changed, for example, from non-3GPP access to 3GPP access or from 3GPP access to non-3GPP access. The following Table 3 shows examples of explicit session access type change indication.

Table 3

Alternatively, the AMF 30c may determine to send a handover trigger indication based on either the NAS signaling from the UEs or its internal configuration. The internal configuration can include factors like UE location, satellite ephemeris, or a change in radio access technology (RAT) information type as indicated by the first on-board satellite radio access node 201 (e.g., an old/source on-board satellite radio access node) for the group of UEs or UEs'sessions as described in options 1 or 2.

Option 1: UEs in group 1 do not change satellite access type as indicated by RAT information, while UEs in group 2 and group 3 change satellite access type. The following Table 4 and Table 5 show examples of an indication that indicates a RAT information type change.

Table 4

Option 2: UEs in group 1 and group 2 do not change satellite access type as indicated by RAT information, while UEs in group 3 change satellite access type.

Table 5

With reference to FIG. 6, upon receiving signaling message indication from the UEs, the first on-board satellite radio access node 201 and/or the on-ground network node groups the UEs into different groups of UEs by based on the signaling message indication from the UEs. The signaling message indication from the UEs may be a radio resource control (RRC) configuration message. The first on-board satellite radio access node 201 may be the source on-board gNB-DU 20-21a. The on-ground network node may be the AMF 30c and/or the on-ground gNB-CU 20-1a. As shown in the example of FIG. 5, UEs 10a-10c are grouped into group 1. UEs 10d-10e are grouped into group 2. UEs 10f-10g are grouped into group 3.

Based on RRC signaling from UEs or on an indication of a gNB-DU handover trigger from on-ground gNB-CU 20-1a or from AMF 30c via on-ground gNB-CU 20-1a, the source on-board gNB-DU 20-21a sends a single UL RRC MESSAGE TRANSFER message to the on-ground gNB-CU 20-1a. The UL RRC MESSAGE TRANSFER message comprises all bearer contexts associated with a group of UEs that indicate a change on the on-board access type. The RRC signaling from UEs inform the on-ground gNB-CU 20-1a that this group of UEs have moved to a cell of the target on-board gNB-DU 20-22a. The cell may be referred to as a target cell.

The on-ground gNB-CU 20-1a sends a per-UE-group CONTEXT SETUP REQUEST message to the target on-board gNB-DU 20-22a to create the bearer context associated with the group of UEs that indicate a change on the on-board access type and establish the related data bearers for the group of UEs. An example of the per-UE-group CONTEXT SETUP REQUEST message is shown in the Table 6.

The target on-board gNB-DU 20-22a responds to the on-ground gNB-CU 20-1a with a single per-UE-group CONTEXT SETUP RESPONSE message for the group of UEs indicated a change on the on-board access type.

The on-ground gNB-CU 20-1a sends a per-UE-group CONTEXT MODIFICATION REQUEST message to the source on-board gNB-DU 20-21a. The per-UE-group CONTEXT MODIFICATION REQUEST message includes a per-UE-group RRC Reconfiguration message scrambled with a group-based RNTI. The per-UE-group RRC Reconfiguration message is used to indicates when to stop the data transmission for the group of UEs that indicate a change on the on-board access type, and to provide the access related configuration information of the target on-board gNB-DU 20-22a. For example, the access related configuration information of the target on-board gNB-DU 20-22a comprises one or more of the target gNB-DU ID, cell IDs, the new group-based RNTI, the target gNB security algorithm identifiers for the selected security algorithms, and/or a dedicated RACH resources, the association between RACH resources and SSB (s) , the association between RACH resources and UE-specific CSI-RS configuration (s) , common RACH resources, and system information of the target cell, etc. The source on-board gNB-DU 20-21a also sends a Downlink Data Delivery Status frame to inform the on-ground gNB-CU 20-1a of any downlink data that was not successfully delivered to the group of UEs.

The source on-board gNB-DU 20-21a forwards the received per-UE-group scrambled RRC Reconfiguration message to the group of UEs according to their indication of on-board access type change and responds to the on-ground gNB-CU 20-1a with a per-UE-group CONTEXT MODIFICATION RESPONSE message. Then, a random- access procedure can be performed by each UE within the group individually to access the target on-board gNB-DU 20-22a. The target on-board gNB-DU 20-22a sends a Downlink Data Delivery Status frame to inform the on-ground gNB-CU 20-1a. Downlink packets, which may include PDCP PDUs not successfully transmitted to the group of UEs, in the source on-board gNB-DU 20-21a, are sent from the on-ground gNB-CU 20-1a to the target on-board gNB-DU 20-22a. The UEs in the group of UEs responds individually to the target on-board gNB-DU 20-22a with an RRC Reconfiguration Complete message.

The target on-board gNB-DU 20-22a sends an UL RRC MESSAGE TRANSFER message to the on-ground gNB-CU 20-1a to convey the received RRC Reconfiguration Complete message. Packets in both the downlink and uplink directions are sent to or received from the group of UEs that indicate a change on the on-board access type. Also, uplink packets are sent from the UEs, which are forwarded to the on-ground gNB-CU 20-1a through the target on-board gNB-DU 20-22a.

The on-ground gNB-CU 20-1a sends a per-UE-group CONTEXT RELEASE COMMAND message to the source on-board gNB-DU 20-21a to release the group of UEs that indicate a change on the on-board access type.

The source on-board gNB-DU 20-21a releases the bearer context associated with group of UEs that indicate a change on the on-board access type and responds the on-ground gNB-CU 20-1a with a per-UE-group CONTEXT RELEASE COMPLETE message.

Table 6

Fully on-board radio access nodes:

Embodiments of the disclosure may be applied to the scenario where the radio access node is fully deployed onboard of a satellite. For example, a gNB or a function split gNB (gNB-CU and gNB-DUs) functions is deployed onboard of a satellite and connected to a an on-ground network node that executes a control plane function, such as an access and management function (AMF) , a session management function (SMF) and/or a user plane function (UPF) via multiple NG-C and NG-U interfaces respectively. The gNBs/gNB-CUs are connected to each other via Xn/X2 interface. In this particular scenario, when satellite constellations shift, the gNB will also need to relocate from its associated UPF 30bs. This leads to a frequent update of NG-U tunnels, modifications in PDU/multicast/broadcast sessions, and potential signaling for gNB-DU handovers for each individual UE connection.

To resolve this issue, the AMF 30c or source on-board gNB may group UEs based on the information within the indication message, coverage group type, and/or other related information from the group of UEs and implement the per-UE-group NG-U tunnel update procedure, modifications of PDU/multicast/broadcast sessions, and/or gNB-CU handover signaling.

As shown in the example of FIG. 7, UEs 10a-10c are grouped into group 1. UEs 10d-10e are grouped into group 2. UEs 10f-10g are grouped into group 3.

With reference to FIG. 8, signaling between entities in the network system is detailed in the following. Examples of UEs 10 may include UE 10a-10g.

● a measurement of one or both of the first and second on-board satellite radio access node 202;

● an indication of physical cell identity (PCI) of one or both of the first and second on-board satellite radio access node 202; and

● an indication showing that the serving on-board satellite radio access node of the UEs is changed.

UEs located in the overlap area between the first and second on-board satellite radio access node 202 or UEs capable of receiving the new satellite-related access SIB can generate the report. Examples of the indication showing the PCIs or showing the change of the serving on-board satellite radio access node are provided in the following Table 7. The SIB change indication reported by UE in the group 2 indicates a change of the serving on-board satellite radio access node by conveying two PCI, i.e., [PCI, PCI2] .

Table 7

Alternatively, the UEs may decide to send non-access stratum (NAS) signaling to the AMF 30c based on pre-configured parameters from the network, such as UE location or satellite ephemeris data. For example, the NAS signaling conveys join, modification, or update of a PDU, multicast, or broadcast session and an indication of access type change of the group of UEs. With reference to TS 29.502, an access type change indicates that the access type of PDU, multicast, or broadcast sessions is changed, for example, from non-3GPP access to 3GPP access or from 3GPP access to non-3GPP access. The following Table 8 shows examples of explicit session access type change indication.

Table 8

Alternatively, the AMF 30c may decide based on the non-access stratum (NAS) signaling from UE or AMF 30c internal configuration e.g., based UE on location information, satellite ephemeris, or an indication of RAT information type change from the source on-board NG-RAN node for the group of UEs or UEs’s essions as given in option 1 or 2 to send a handover trigger indication toward the source on-board NG-RAN node.

Option 1: UEs in group 1 do not change satellite access type as indicated by RAT information, while UEs in group 2 and group 3 change satellite access type. The following Table 9 and Table 10 show examples of an indication that indicates a RAT information type change.

Table 9

Table 10

With reference to FIG. 8, upon receiving signaling message indication from the UEs, the first on-board satellite radio access node 201 and/or the on-ground network node groups the UEs into different groups of UEs by based on the signaling message indication from the UEs. The signaling message indication from the UEs may be a radio resource control (RRC) configuration message. The first on-board satellite radio access node 201 may be the source on-board gNB 20a. The on-ground network node may be an access and mobility management function (AMF) . As shown in the example of FIG. 7, UEs 10a-10c are grouped into group 1. UEs 10d-10e are grouped into group 2. UEs 10f-10g are grouped into group 3.

Initiation of handover may be based on various handover trigger events, which may comprise one or more of RRC signaling from UE, an internal configuration of the source on-board gNB 20a, an indication of handover trigger from the AMF 30c, and a handover required response (command) from the AMF 30c for PDU and/or MBS sessions associated with a group of UEs that indicate a change on the on-board access type. In response to the handover trigger events, the source on-board gNB 20a triggers a handover request toward the target on-board gNB 20b node to initiate a group-based setup, modification, release of resources for the PDU and/or MBS sessions associated with a group of UEs that indicate a change on the on-board access type. An example of a per-UE-group NG session resource setup signaling message is given as an example in below Table 11) .

The target on-board gNB 20b may respond the handover request from the source on-board gNB 20a by establishing, modifying, or requesting releasing resources for the PDU and/or MBS sessions context associated with the group of UEs indicated in the handover request provided from the source on-board gNB 20a. The target on-board gNB 20b may also trigger a N2 Path Switch Request toward AMF 30c to inform the AMF 30c that this group of UEs have moved to a cell of the target on-board gNB 20b. The cell may be referred to as a target cell. The N2 Path Switch Request may include a list of PDU/MBS Sessions to be switched for the group of UEs indicated in the handover request.

Based on response from the target on-board gNB 20b, the source on-board gNB 20a triggers the Uu handover by sending a group-based RRC message scrambled with a group RNTI to the group of UEs indicated in the handover request, containing the information required to access information of the target on-board gNB 20b, such as the target gNB cell ID, the new C-RNTI, the target gNB security algorithm identifiers for the selected security algorithms and/or a dedicated random access channel (RACH) resources, the association between RACH resources and one or more synchronization signal blocks (SSBs) , the association between RACH resources and one or more UE-specific channel state information (CSI) -reference signal (RS) configurations, common RACH resources, and system information of the target cell, etc.

The AMF 30c send an Update SM Context request to SMF 30d to request the SMF 30d to update Session Management (SM) Context for the respective PDU/MBS Sessions of the group of UEs. The Update SM Context request may include the lists of PDU/MBS Sessions related to the group of UEs indicated in the N2 Path Switch Request. For the lists of PDU/MBS Sessions related to the group of UEs indicated in the N2 Path Switch Request, the SMF 30d sends an N4 Session Modification Request message to the UPF 30b. Then the UPF 30b switches the path for PDU/MBS Sessions related to the group of UEs indicated in the N2 Path Switch Request to the target on-board gNB 20b and returns an N4 Session Modification Response message to the SMF 30d indicating that the path of PDU/MBS Sessions related to the group of UEs indicated in the N2 Path Switch Request are switched. The SMF 30d sends through interface N11 an Update SM Context response to the AMF 30c indicating the PDU/MBS Sessions related to the group of UEs which have been switched successfully.

The AMF 30c sends an N2 Path Switch Request Acknowledgment to the target on-board gNB 20b indicating that the lists of PDU/MBS Sessions related to the group of UEs indicated in the N2 Path Switch Request were successfully switched to new N3 interface that connects the target on-board gNB 20b to the Core network.

Based on Path Switch Request Acknowledgment from AMF 30c, the target on-board gNB 20b confirms success of the handover by sending to the source on-board gNB 20a a request to release resources of the PDU/MBS Sessions associated with the group of UEs which have been successfully switched or handed-over.

Definition of the signaling messages for Per-UE-group NG session is illustrated in the following Tables.

Table 11

Table 12

Table 13

Table 14

Table 15

The disclosure provides a method for supporting satellite access with on-board radio access node functionality as per requirement of release 19 satellite access discussion. The benefits and innovation aspects of the disclosure include:

(1) . The disclosure introduces new per-UE-group session or context management and/or handover related signaling and procedures to handle the signaling overload issues in F1-C and NG-C control plane interface.

(2) . The disclosure also introduces new set of signaling and indication or triggers to assist realizing the per-UE-group session or context management and handover signaling to handle the scenario where access node is onboard of satellite.

With reference to FIG. 9, the UE 100 may include a processor 11a, a memory 12a, and a transceiver 13a. The processor 11a is configured to call and run a computer program stored in the memory 12a, to cause UE 10 in which the processor 11 is installed to execute the disclosed method, steps, and/or functions of a UE. The UE 100 is an example of the UE 10, and UEs 10a-10g. The transceiver 13a may include baseband circuitry and radio frequency (RF) circuitry.

With reference to FIG. 10, the network node 200 is a network device and may include a processor 21a, a memory 22a, and a transceiver 23a. The processor 21a is configured to call and run a computer program stored in the memory 22a, to cause UE 10 in which the processor 11 is installed to execute the method, steps, and/or functions of a network node. The network node 20 is an example of the gNB 20a, gNB-CU 20-1a, gNB-DU 20-21a, gNB-DU 20-22a, on-board gNB 20b, gNB-CU 20-1c, gNB-DU 20-2c, gNB 20d, first on-board satellite radio access node 201, a second on-board satellite radio access node 202, UPF 30b, AMF 30c, and SMF 30d. The transceiver 23a may include baseband circuitry and radio frequency (RF) circuitry.

With reference to FIG. 11, the embodiment of the disclosure also provides a chip 700 that may correspond to a user equipment 10 in the embodiments of the disclosure. The chip 700 may implement a corresponding process realized by the user equipment 10 in various methods of the embodiments of the disclosure. The chip 700 includes a processor 701, and the processor 701 may call and run a computer program from memory to implement the methods in the embodiments of the present application.

Optionally, the chip 700 may also include a memory 702. In particular, the processor 701 may call and run the computer program from the memory 702 to implement the methods in the embodiments of the present application.

Moreover, the memory 702 may be a separate device from the processor 701 or may be integrated into the processor 701.

Optionally, the chip 700 may further include an input interface 703. Note that the processor 701 may control the input interface 703 to communicate with other devices or chips, specifically, to obtain messages or data sent by other devices or chips.

Optionally, the chip 700 may further include an output interface 704. Note that the processor 701 may control the output interface 704 to communicate with other devices or chips, specifically, to output messages or data to other devices or chips.

With reference to FIG. 12, the embodiment of the disclosure also provides another chip 800 that may correspond to the gNB 20 in the embodiment of the disclosure, and the chip 800 may implement the corresponding processes implemented by the gNB 20 in the various methods of the embodiments of the disclosure. The chip 800 includes a processor 801, and the processor 801 may call and run a computer program from the memory 802 to implement the methods in the embodiments of the present application.

Optionally, the chip 800 may further include a memory 802. In particular, the processor 801 may call and run the computer program from the memory 802 to implement the methods in the embodiments of the present application.

Wherein the memory 802 may be a separate device from the processor 801 or may be integrated into the processor 801.

Optionally, the chip 800 may also include an input interface 803. In particular, the processor 801 may control the input interface 803 to communicate with other devices or chips, specifically, to obtain messages or data sent by other devices or chips.

Optionally, the chip may further include an output interface 804. In particular, the processor 801 may control the output interface 804 to communicate with other devices or chips, specifically, to output messages or data to other devices or chips.

It should be understood that the processor in the embodiments of the present application may be an integrated circuit chip with signal processing capabilities. In implementation, the steps of the above method embodiments may be accomplished through integrated logic circuits in the form of hardware in the processor or instructions in the form of software. The processor described above may be a general-purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) , or other programmable logic devices, discrete gate or transistor logic devices, and discrete hardware components. Various methods, steps, and logic block diagrams of the disclosure in the embodiments of the present application may be implemented or performed. The general-purpose processor may be a microprocessor, or the processor may also be any conventional processor, etc. The steps of the methods disclosed in conjunction with the embodiments of the present application may be directly embodied in and performed by a hardware decoding processor, or performed with a combination of hardware and software modules in the decoding processor. The software module may be located in random memory, flash memory, read-only memory, programmable read-only memory or electrically erasable programmable memory, registers, and other storage media well established in the art. The storage medium is located in memory, and the processor reads the messages in the memory and realize the steps of the method described above in combination with its hardware.

It will be appreciated that the memory in an embodiment of the present application may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Among other things, the non-volatile memory may be Read-Only Memory (ROM) , Programmable ROM (PROM) , Erasable Programmable Read-Only Memory (EPROM) , Electrically Erasable Programmable Read-Only Memory (Electrically EPROM, EEPROM) or flash memory. The volatile memory may be Random Access Memory (RAM) , which is used as an external cache. For example, not for limiting, many forms of RAM are available, such as Static RAM (SRAM) , Dynamic RAM (DRAM) , Synchronous DRAM (SDRAM) , Double Data Rate SDRAM (DDRAM) , Double Data Rate SDRAM (DDRAM) , Enhanced Synchronous Dynamic Random Access Memory (ESDRAM) , Synchlink DRAM (SLDRAM) , and Direct Rambus RAM (DR RAM) . It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

Embodiments of the present application also provide a computer program product comprising computer program instructions.

Optionally, the computer program product may be applied to the network nodes in the embodiment of the disclosure, and the computer program instructions cause the computer to execute the corresponding processes implemented by the network nodes in the various methods of the embodiment of the disclosure, which are not described herein for brevity.

Optionally, the computer program product may be applied to the user equipment (s) in the embodiment of the present application, and the computer program instructions cause the computer to perform the corresponding processes realized by the user equipment (s) in the various methods of the embodiment of the present application, which are not repeated herein for brevity.

An embodiment of the disclosures also provides a computer program.

Optionally, the computer program may be applied to the network nodes in the embodiment of the present application, and when the computer program is run on the computer, causes the computer to execute the corresponding processes implemented by the network nodes in the various methods of the embodiment of the present application, which are not described herein for the sake of brevity.

Optionally, the computer program may be applied to the user equipment (s) in the embodiments of the present application, and when the computer program is run on the computer, causes the computer to execute the corresponding processes realized by the user equipment (s) in the respective methods of the embodiments of the present application, which will not be repeated herein for brevity.

One of ordinary skill in the art may realize that the units and algorithmic steps described in conjunction with the various examples of the embodiments disclosed herein are capable of being implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the particular application and design constraints of the technical solution. A person skilled in the art may use different methods to implement the described functions for each particular application, but such implementations should not be considered outside the scope of this application.

Those skilled in the art may appreciate that, for the convenience and brevity of the description, the specific working processes of the above-described systems, apparatuses and units can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated herein.

In the several embodiments provided in this application, it should be understood that the systems, devices and methods disclosed can be realized in other ways. For example, the above-described implementations of the device are merely schematic, e.g., the division of the unit, which is merely a logical functional division, may be divided in other ways when actually implemented, e.g., multiple units or components may be combined or may be integrated into another system, or some features may be ignored, or not implemented. Additionally, the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, which may be electrical, mechanical or otherwise.

The unit illustrated as a separated component may or may not be physically separated, and the component shown as a unit may or may not be a physical unit, i.e., it may be located in one place, or it may be distributed over a plurality of network units. Some or all of these units may be selected to fulfill the purpose of the present embodiment scheme according to actual needs.

Additionally, each functional unit in various embodiments of the present application may be integrated in a single processing unit, or each unit may exist as a separate entity, or two or more units may be integrated in a single unit.

The functionality, when implemented as a software functional unit and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application may be embodied in the form of a software product that is essentially or contributes to the prior art, or portions of the technical solution may be embodied in the form of a software product that is stored in a storage medium and includes a number of instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc. ) to perform all or some of the steps of the various embodiments of the present application. all or some of the steps of the various embodiments of the present application. The aforementioned storage medium is a non-volatile storage medium, including a portable disk, a removable hard disk, a read-only memory (Read-Only Memory, ROM) , a random access memory (Random Access Memory, RAM) , a magnetic disk, or a CD-ROM, and other media in which the program code can be stored.

While the present disclosure has been described in connection with what is considered the most practical and preferred embodiments, it is understood that the present disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.

Claims

A satellite access method, comprising:

sending a signaling message indication from user equipments (UEs) to a first on-board satellite radio access node and/or an on-ground network node, wherein the signaling message indication indicates a change of a serving on-board satellite radio access node;

grouping the UEs into different groups of UEs by the first on-board satellite radio access node and/or the on-ground network node based on the signaling message indication from the UEs; and

triggering by the first on-board satellite radio access node and/or the on-ground network node a handover of at least one of the groups of UEs from the first on-board satellite radio access node to a second on-board satellite radio access node, wherein the handover of at least one of the groups of UEs is based on the signaling message indication from the UEs and/or a per-UE-group signaling message provided by the first on-board satellite radio access node and/or the on-ground network node.
The satellite access method of claim 1, further comprising initiating by the on-ground network node, the first on-board satellite radio access node, and/or the second on-board satellite radio access node per-UE-group establishment, addition, modification, and/or releasing of the bearers context and/or sessions resources associated with the at least one of groups of UEs.
The satellite access method of claim 1, further comprising sending by the first on-board satellite radio access node a per-UE-group handover signaling to the at least one of the groups of UEs indicating the handover to the second on-board satellite radio access node.
The satellite access method of any of claim 1 to claim 3, wherein the on-ground network node is an access and mobility management function (AMF) and/or a centralized unit of a base station (gNB-CU) .
The satellite access method of any of claim 1 to claim 3, wherein the per-UE-group signaling message is a message provided from on-board satellite radio access node to the on-ground network node.
The satellite access method of any of claim 1 to claim 3, wherein the signaling message indication from the UEs is a non-access stratum (NAS) message provided from the UEs to the on-ground network node, wherein the signaling message indication is a pre-configured parameters which comprises UE location or satellite ephemeris data.
The satellite access method of any of claim 1 to claim 3, wherein the signaling message indication from the UEs is a radio resource control (RRC) configuration message.
The satellite access method of claim 7, wherein the signaling message indication and/or the per-UE-group signaling message includes at least one of: coverage group type change, reference location change, reference time change, coverage and/or measurement change, frequency change, physical cell identity change, satellite access related SIB change, satellite ID change, UE session access type change and/or other associated information.
The satellite access method of claim 7, wherein the signaling message indication and/or the per-UE-group signaling message includes one or more of:

a measurement of one or both of the first and second on-board satellite radio access node;

an indication of physical cell identity (PCI) of one or both of the first and second on-board satellite radio access node; and

an indication indicating that the serving on-board satellite radio access node of the UEs is changed.
The satellite access method of claim 6, wherein the NAS message conveys join, modification, or update of a PDU, multicast, or broadcast session and an indication of access type change of the at least one of the groups of UEs.
The satellite access method of claim 1, wherein the sessions associated with the at least one of the groups of UEs comprise protocol data unit (PDU) sessions or multimedia broadcast/multicast service (MBS) sessions.
The satellite access method of claim 1, further comprising:

sending, from the first on-board satellite radio access node, a group-based radio resource control (RRC) message scrambled with a group radio network temporary identifier (RNTI) to the at least one of the groups of UEs.
The satellite access method of claim 12, wherein the group-based RRC message comprises a per-UE-group RRC reconfiguration message scrambled with a group-based RNTI to indicates when to stop data transmission for the at least one of the groups of UEs that have indicated a change on on-board access type, and/or to provide access related configuration information of the second on-board satellite radio access node.
The satellite access method of claim 1, further comprising:

the second on-board satellite radio access node transmitting a path switching request to the on-ground network node to request path switching for the bears context or the sessions for the at least one of the groups of UEs.
The satellite access method of claim 1, wherein the first on-board satellite radio access node comprises a first on-board distributed unit of a base station;

the second on-board satellite radio access node comprises a second on-board distributed unit of the base station; and the on-ground network node comprises an on-ground centralized unit of the base station.
The satellite access method of claim 15, wherein the first on-board distributed unit sends a single uplink (UL) RRC message transfer message to the on-ground centralized unit of the base station, the UL RRC message transfer message comprises all bearer contexts associated with the at least one of the groups of UEs that indicate a change on on-board access type.
The satellite access method of claim 16, wherein the on-ground centralized unit of the base station sends a per-UE-group context setup request message to the second on-board distributed unit of the base station to create bearer context associated with the at least one of the groups of UEs that indicate a change on the on-board access type and establish related data bearers for the at least one of the groups of UEs; and

the second on-board distributed unit of the base station responds to the on-ground centralized unit of the base station a per-UE-group context setup response message.
The satellite access method of claim 17, wherein the on-ground centralized unit of the base station sends a per-UE-group Context modification request message to the first on-board distributed unit;

the per-UE-group context modification request message includes a per-UE-group RRC reconfiguration message scrambled with a group-based RNTI;

the per-UE-group RRC Reconfiguration message is used to indicates when to stop data transmission for the at least one of the groups of UEs that indicate a change on the on-board access type, and/or to provide access related configuration information of the second on-board distributed unit of the base station; and

the first on-board distributed unit forwards the received per-UE-group scrambled RRC Reconfiguration message to the at least one of the groups of UEs according to an indication of on-board access type change of at least one of the groups of UEs and responds to the on-ground centralized unit of the base station with a per-UE-group context modification response message.
The satellite access method of claim 18, wherein the access related configuration information of the second on-board distributed unit of the base station comprises one or more of: a second gNB-DU ID, cell IDs, a new group-based RNTI, a second gNB security algorithm identifiers for a selected security algorithms, and/or a random access channel (RACH) resources, association between RACH resources and one or more synchronization signal blocks (SSBs) , association between RACH resources and one or more UE-specific channel state information (CSI) -reference signal (RS) configurations, common RACH resources, and/or system information of a second cell.
The satellite access method of claim 18, wherein the UEs in the at least one of the groups of UEs responds to the second on-board distributed unit of the base station with an RRC reconfiguration complete message; and

the second on-board distributed unit of the base station sends an UL RRC message transfer message to the on-ground centralized unit of the base station to convey the received RRC reconfiguration complete message.
The satellite access method of claim 20, wherein the on-ground centralized unit of the base station sends a per-UE-group context release command message to the first on-board distributed unit to release the at least one of the groups of UEs that indicate a change on the on-board access type; and

the first on-board distributed unit releases the bearer context associated with the at least one of the groups of UEs that indicate a change on the on-board access type and responds the on-ground centralized unit of the base station with a UE context release complete message.
The satellite access method of claim 1, wherein the first on-board satellite radio access node comprises a first on-board base station;

the second on-board satellite radio access node comprises a second on-board base station; and

the on-ground network node comprises an access and mobility management function (AMF) .
The satellite access method of claim 22, wherein the first on-board base station triggers a handover request toward the second on-board base station node to initiate a group-based setup, modification, release of resources for the PDU and/or MBS sessions associated with the at least one of the groups of UEs that indicate a change on an on-board access type;

the second on-board base station responds the handover request from the first on-board base station by establishing, modifying, or requesting releasing resources for the PDU and/or MBS sessions context associated with the at least one of the groups of UEs indicated in the handover request provided from the first on-board base station; and

based on response from the second on-board base station, the first on-board base station triggers a Uu handover by sending a group-based RRC message scrambled with a group RNTI to the at least one of the groups of UEs indicated in the handover request.
The satellite access method of claim 23, wherein the second on-board base station triggers a N2 path switch request toward the AMF to inform the AMF that the at least one of the groups of UEs have moved to a cell of the second on-board base station, the N2 path switch request includes a list of PDU/MBS sessions to be switched for the at least one of the groups of UEs indicated in the handover request.
The satellite access method of claim 23, wherein the scrambled group-based RRC message comprises one or more of:

a second gNB cell ID, a new C-RNTI (Cell-RNTI) , second gNB security algorithm identifiers for selected security algorithms and/or dedicated random access channel (RACH) resources, association between RACH resources and one or more synchronization signal blocks (SSBs) , association between RACH resources and one or more UE-specific channel state information (CSI) -reference signal (RS) configurations, common RACH resources, and/or system information of a second cell.
The satellite access method of claim 23, wherein the AMF send an update SM context request to a session management function (SMF) to request the SMF to update session management (SM) context for the respective PDU/MBS sessions of the at least one of the groups of UEs;

the update SM context request includes lists of PDU/MBS sessions related to the at least one of the groups of UEs indicated in the N2 path switch request;

for the lists of PDU/MBS sessions related to the at least one of the groups of UEs indicated in the N2 path switch request, the SMF sends an N4 Session Modification Request message to a user plane function (UPF) ;

the UPF switches a path for PDU/MBS sessions related to the at least one of the groups of UEs indicated in the N2 path switch request to the second on-board base station and returns an N4 session modification response message to the SMF indicating that the path of PDU/MBS sessions related to the at least one of the groups of UEs indicated in the N2 path switch request are switched; and

the SMF sends an update SM context response to the AMF indicating the PDU/MBS sessions related to the at least one of the groups of UEs which have been switched successfully.
The satellite access method of claim 26, wherein the AMF sends a path switch request acknowledgment to the second on-board base station indicating that the lists of PDU/MBS sessions related to the at least one of the groups of UEs indicated in the N2 path switch request were successfully switched to a new N3 interface that connects the second on-board base station to a core network; and

based on path switch request acknowledgment from AMF, the second on-board base station confirms success of the handover by sending to the first on-board base station a request to release resources of the PDU/MBS sessions associated with the at least one of the groups of UEs which have been successfully switched or handed-over.
A system comprising:

user equipments (UEs) ;

a first on-board satellite radio access node; and

an on-ground network node;

wherein the user equipments (UEs) are configured to send a signaling message indication to the first on-board satellite radio access node and/or the on-ground network node, wherein the signaling message indication indicates a change of a serving on-board satellite radio access node;

the first on-board satellite radio access node and/or the on-ground network node is configured to group the UEs into different groups of UEs based on the signaling message indication from the UEs;

the first on-board satellite radio access node and/or the on-ground network node is configured to trigger a handover of at least one of the groups of UEs from the first on-board satellite radio access node to a second on-board satellite radio access node; and

the handover of at least one of the groups of UEs is based on the signaling message indication from the UEs and/or a per-UE-group signaling message provided by the first on-board satellite radio access node and/or the on-ground network node.
The system of claim 28, wherein the first on-board satellite radio access node comprises a base station; and

the on-ground network node is an access and mobility management function (AMF) .
The system of claim 28, wherein the first on-board satellite radio access node comprises a first on-board distributed unit of a base station;

the second on-board satellite radio access node comprises a second on-board distributed unit of the base station; and

the on-ground network node comprises an on-ground centralized unit of the base station.