Communication device, and communication method

Abstract

To provide a communication device capable of efficient switching of satellite beams in a non-terrestrial network, a communication method, and an integrated circuit.SOLUTION: A user device 1260 is a communication device that includes: a transceiver 1270 that receives a piece of information indicating the reference point of a serving cell, which is provided by at least one satellite beam, and the distance from that reference point; and a circuit 1280 that determines whether or not to perform a switch from at least one satellite beam to the target satellite beam based on the distance from the reference point of the serving cell and the distance between the communication device and the reference point.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present disclosure relates to the transmission and reception of signals in communication systems. In particular, the present disclosure relates to methods and apparatus for such transmission and reception. [Background technology]

[0002] The 3GPP (3rd Generation Partnership Project)® is developing technical specifications for next-generation mobile phone technology, also known as fifth generation (5G), including the "NR" (New Radio) radio access technology (RAT) that operates in frequency bands up to 100 GHz. NR is a successor to technologies such as LTE (Long Term Evolution) and LTE Advanced (LTE-A).

[0003] In systems such as LTE, LTE-A, and NR, further modifications and options may facilitate efficient operation of the communication system as well as specific equipment associated with the system. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP TS 38.300 v15.6.0 [Non-patent document 2] 3GPP TS 38.211 v15.6.0 [Non-patent document 3] ITU-R M.2083 [Non-patent document 4] TR 38.913 [Non-Patent Document 5] 3GPP TS 38.211 V15.3.0 [Non-patent document 6] TS 23.501 v16.1.0 [Non-Patent Document 7] E. Dahlman, et al., 5GNR: The Next Generation Wireless Access Technology, 1st Edition [Non-patent document 8] 3GPP TR 38.811, Study on New Radio (NR) to support non-terrestrial networks, version 15.2.0 [Non-Patent Document 9] 3GPP TR 38.821, Solutions for NR to support non-terrestrial networks, version 16.0.0 Summary of the Invention [Problem to be solved by the invention]

[0005] One non-limiting, exemplary embodiment facilitates efficient handover and beam switching in non-terrestrial networks. [Means for solving the problem]

[0006] In one embodiment, the technology disclosed in this specification provides a communications device comprising: a transceiver that receives information indicating a reference point of a serving cell provided by at least one satellite beam and a distance from the reference point of the serving cell; and a circuit that determines whether to switch from the at least one satellite beam to a target satellite beam based on the distance from the reference point of the serving cell and the distance between the communications device and the reference point.

[0007] It should be noted that the general or specific embodiments may be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any combination thereof.

[0008] Further benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. These benefits and / or advantages may be obtained individually by the various embodiments and features of the specification and drawings, and it is not necessary for all of these embodiments and features to be present in order to obtain one or more of such benefits and / or advantages. [Brief explanation of the drawings]

[0009] Exemplary embodiments will now be described in more detail with reference to the accompanying figures and drawings. [Figure 1] 1 illustrates an example architecture of a 3GPP NR system. [Figure 2] 1 is a schematic diagram showing the separation of functions between NG-RAN and 5GC. [Figure 3] FIG. 1 is a sequence diagram of an RRC connection establishment / reconfiguration procedure. [Figure 4] A schematic diagram showing the usage scenarios of enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC). [Figure 5] FIG. 1 is a block diagram illustrating the architecture of an exemplary 5G system in a non-roaming scenario. [Figure 6] A non-terrestrial network (NTN) scenario is shown, where transmission between terminals is via satellites and remote radio equipment including NTN gateways. [Figure 7] It shows a non-terrestrial network (NTN) scenario, where transmission between terminals is via a satellite with a gNB as the scheduling device. [Figure 8] This is the case when one cell (PCI) is mapped onto multiple satellite beams. [Figure 9] This is the case when one cell (PCI) is mapped to one satellite beam. [Figure 10] This shows the terrestrial mobile cell scenario in NTN. [Figure 11]1 shows the parameters of the ephemeris. [Figure 12] FIG. 1 is a block diagram showing a base station and user equipment (UE). [Figure 13] FIG. 2 is a block diagram illustrating a satellite beam switching circuit of a user equipment. [Figure 14] FIG. 2 is a block diagram showing a satellite beam switching circuit of a base station. [Figure 15] FIG. 1 is a block diagram showing the procedure of a communication method in a UE. [Figure 16] FIG. 2 is a block diagram showing the procedure of a communication method in a base station. [Figure 17] FIG. 1 is a block diagram showing the procedure of a communication method in a UE. [Figure 18] FIG. 2 is a block diagram showing the procedure of a communication method in a base station. [Figure 19] 1 shows the definition of satellite coverage by beam direction and diameter. [Figure 20] 1 illustrates the definition of satellite beam coverage by non-overlapping rectangular shapes. [Figure 21] 1 shows the definition of satellite beam coverage by satellite beam center and in-coverage distance. [Figure 22] 1 illustrates signaling between a UE, a source base station, and a target base station in a RACH-based handover. [Figure 23] 1 shows signaling between a UE, a source base station, and a target base station in a RACH-less handover. [Figure 24] 1 illustrates signaling between a UE, a source base station, and a target base station in a handover without RRC reconfiguration signaling. [Figure 25] 1 illustrates signaling between a UE, a source base station, and multiple target base stations during handover. [Figure 26] 1 shows signaling between a UE and a base station for beam switching. [Figure 27] FIG. 1 is a block diagram illustrating user equipment. DETAILED DESCRIPTION OF THE INVENTION

[0010] <5G NR system architecture and protocol stack> 3GPP is working on the next release of fifth-generation cellular technology (simply known as 5G), which includes the development of a new radio access technology (NR) that will operate in frequencies up to 100 GHz. The first version of the 5G standard was completed at the end of 2017, allowing for the testing and commercial deployment of smartphones compliant with the 5G NR standard.

[0011] In particular, the overall system architecture assumes an NG-RAN (Next Generation - Radio Access Network) with gNBs (gNodeBs), which terminate NG radio access user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC: Radio Resource Control) protocols towards UEs. The gNBs are interconnected with each other by Xn interfaces. Furthermore, the gNBs are connected to the NGC (Next Generation Core) by Next Generation (NG) interfaces, more specifically to the AMF (Access and Mobility Management Function) (e.g., a specific core entity running the AMF) by the NG-C interface, and to the UPF (User Plane Function) (e.g., a specific core entity running the UPF) by the NG-U interface. Figure 1 shows the architecture of the NG-RAN (see Section 4 of Non-Patent Document 1).

[0012] The user plane protocol stack in NR (see, for example, Section 4.4.1 of Non-Patent Document 1) includes a PDCP (Packet Data Convergence Protocol) sublayer, an RLC (Radio Link Control) sublayer, and a MAC (Medium Access Control) sublayer, which are terminated at the gNB on the network side. In addition, a new access stratum (AS) sublayer (SDAP: Service Data Adaptation Protocol) is introduced above PDCP (see, for example, Section 6.5 of Non-Patent Document 1). NR also defines a control plane protocol stack (see, for example, Section 4.4.2 of Non-Patent Document 1). An overview of Layer 2 functions is provided in Section 6 of Non-Patent Document 1. The functions of the RDCP sublayer, RLC sublayer, and MAC sublayer are respectively described in sections 6.4, 6.3, and 6.2 of Non-Patent Document 1. The functions of the RRC layer are described in section 7 of Non-Patent Document 1.

[0013] The Medium Access Control (MAC) layer handles, for example, logical channel multiplexing and scheduling and scheduling-related functions (including handling various numerologies).

[0014] The physical layer (PHY) is responsible for, for example, coding, PHY HARQ processing, modulation, multi-antenna processing, and mapping of signals to appropriate physical time-frequency resources. Furthermore, the physical layer (PHY) handles mapping of transport channels to physical channels. The physical layer (PHY) provides services to the MAC layer in the form of transport channels. A physical channel corresponds to a set of time-frequency resources used for transmitting a specific transport channel, and each transport channel is mapped to a corresponding physical channel. For example, physical channels include the PRACH (Physical Random Access Channel), PUSCH (Physical Uplink Shared Channel), and PUCCH (Physical Uplink Control Channel) for the uplink, and the PDSCH (Physical Downlink Shared Channel), PDCCH (Physical Downlink Control Channel), and PBCH (Physical Broadcast Channel) for the downlink.

[0015] NR use cases / deployment scenarios include enhanced mobile broadband (eMBB), ultra-reliable and low-latency communications (URLLC), and massive machine-type communications (mMTC), which have diverse requirements for data rates, latency, and coverage. For example, eMBB is expected to support peak data rates (20 Gbps downlink and 10 Gbps uplink) and user-perceived data rates that are on the order of three times higher than those offered by IMT-Advanced. In contrast, URLLC has more stringent requirements, including extremely low latency (user plane latency of 0.5 ms uplink and downlink, respectively) and high reliability (1-10 Mbps within 1 ms). -5) is imposed. Furthermore, mMTC requires high connection density (1 km 2 1,000,000 devices per second), wide coverage in harsh environments, and extremely long battery life (15 years) to lower device costs may be desirable.

[0016] Therefore, OFDM numerology (e.g., subcarrier spacing, OFDM symbol duration, cyclic prefix (CP) duration, number of symbols per scheduling interval) suitable for one use case may not work well for another use case. For example, low-latency services may preferably require a shorter symbol duration (and therefore a larger subcarrier spacing) and / or fewer symbols per scheduling interval (also referred to as TTI) than mMTC services. Furthermore, deployment scenarios with large channel delay spreads may preferably require a longer cyclic prefix (CP) duration than scenarios with small delay spreads. To maintain a similar cyclic prefix (CP) overhead, the subcarrier spacing should be optimized depending on the delay spread. NR may support more than one value of subcarrier spacing. Therefore, subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, ... are currently being considered. Symbol duration T u and the subcarrier spacing Δf is given by the formula Δf=1 / T u As in LTE systems, the term "resource element" can be used to denote the smallest resource unit consisting of one subcarrier for the length of one OFDM / SC-FDMA symbol.

[0017] In the new radio system 5G NR, for each numerology and carrier, a resource grid of sub-carriers and OFDM symbols is defined for each of the uplink and downlink. Each element in the resource grid is called a resource element and is identified based on the frequency index in the frequency domain and the symbol position in the time domain (see Non-Patent Document 2).

[0018] <5G NR function split between NG-RAN and 5GC> Figure 2 shows the function split between NG-RAN and 5GC. The logical nodes of NG-RAN are gNB or ng-eNB (next-generation eNB). The logical nodes of 5GC are AMF, UPF, and SMF.

[0019] gNB and ng-eNB handle the following main functions in particular. - Functions of radio resource management such as radio bearer control, radio admission control, connection mobility control, and dynamic resource allocation (scheduling) to the UE in both the uplink and downlink directions - IP header compression, encryption, and data integrity protection - Selection of AMF at UE attachment when the routing to AMF cannot be determined from the information provided by the UE - Routing of user plane data to UPF - Routing of control plane information to AMF - Establishment and release of connections - Scheduling and transmission of paging messages - Scheduling and transmission of system broadcast information (sent from AMF or OAM) - Setting of measurements and measurement reports for mobility and scheduling - Transport-level packet marking in the uplink - Session Management - Network slicing support - QoS flow management and mapping to data radio bearers - Support for UEs in RRC_INACTIVE state - NAS message delivery function - Wireless Access Network Sharing - Dual Connection - Tight interworking between NR and E-UTRA

[0020] The Access and Mobility Management Function (AMF) handles the following main functions: - Termination of Non-Access Stratum (NAS) signaling - NAS signaling security - Access Stratum (AS) security control - Core Network (CN) inter-node signaling for mobility between 3GPP access networks - Idle mode UE reachability (including control and execution of paging retransmissions) - Registration Area Management - Support for intra-system and inter-system mobility - Access authentication - Access authentication, including roaming rights checks - Mobility management controls (subscriptions and policies) - Network slicing support - Selection of Session Management Function (SMF) Furthermore, the User Plane Function (UPF) handles the following main functions:

[0021] - Anchor points for RAT - internal / RAT - inter mobility (when applicable) - External PDU session point of connection to the data network - Packet routing and forwarding - User - plane part of packet inspection and policy rule enforcement - Traffic usage reporting - Uplink classifier to support routing of traffic flows to the data network - Branching point to support multi - home PDU sessions - User - plane QoS handling (e.g., packet filtering, gating, UL / DL rate enforcement) - Verification of uplink traffic (mapping from SDF to QoS flow) - Buffering of downlink packets and triggering of downlink data notifications

[0022] Finally, the Session Management Function (SMF) processes the following main functions. - Session management - Allocation and management of UE IP addresses - Selection and control of the UP function - Configuration of traffic steering in the User - plane Function (UPF) to route traffic to the correct destination - Policy enforcement and QoS control part - Downlink data notification

[0023] <Procedures for establishment and re - configuration of RRC connection> Figure 3 shows the interactions between the UE, gNB, and AMF (5GC entity) in the NAS part when the UE transitions from RRC_IDLE to RRC_CONNECTED (see Non - Patent Document 1).

[0024] RRC is the higher layer signaling protocol used to configure the UE and the gNB. In particular, during this transition, the AMF creates UE context data (including, for example, PDU session context, security keys, UE radio capabilities, and UE security capabilities) and sends it to the gNB via an INITIAL CONTEXT SETUP REQUEST. The gNB then activates AS security with the UE by sending a SecurityModeCommand message to the UE, and the UE responds with a SecurityModeComplete message. The gNB then performs reconfiguration to establish signaling radio bearer 2 (SRB2) and data radio bearers (DRBs) by sending an RRCReconfiguration message to the UE and receiving an RRCReconfigurationComplete message from the UE in response. In the case of a signaling-only connection, these steps related to RRCReconfiguration are skipped because SRB2 and DRBs are not established. Finally, the gNB notifies the AMF by means of an INITIAL CONTEXT SETUP RESPONSE that the establishment procedure is complete.

[0025] Therefore, the present disclosure provides a 5th Generation Core (5GC) entity (e.g., AMF, SMF, etc.), the 5th Generation Core entity comprising: control circuitry that, in operation, establishes a Next Generation (NG) connection with a gNodeB; and a transmitter that, in operation, transmits an initial context setup message to the gNodeB over the NG connection to establish a signaling radio bearer between the gNodeB and a user equipment (UE). Specifically, the gNodeB transmits Radio Resource Control (RRC) signaling including a resource allocation configuration information element (IE) to the UE over the signaling radio bearer. The UE performs uplink transmission or downlink reception based on the resource allocation configuration.

[0026] <IMT usage scenarios after 2020> Figure 4 shows some use cases for 5G NR. The 3GPP (3rd Generation Partnership Project) New Radio (3GPP NR) is considering three use cases to support various services and applications in IMT-2020. The Phase 1 specifications for enhanced mobile broadband (eMBB) have been finalized. Current and future work includes standardization of ultra-reliable and low-latency communications (URLLC) and large-scale machine-type communications, in addition to further extending support for eMBB. Figure 4 shows some examples of IMT usage scenarios expected after the year 2000 (see, for example, Figure 2 in Non-Patent Document 3).

[0027] URLLC use cases have stringent requirements for capabilities such as throughput, latency, and availability, and are envisioned as one of the enablers for future vertical applications, such as wireless control of industrial manufacturing and production processes, remote medical surgery, power distribution automation in smart grids, and transportation safety. URLLC's ultra-high reliability is supported by identifying technologies to meet the requirements set by [Non-Patent Document 4]. Key requirements for Release 15 NR URLLC include a target user plane latency of 0.5 ms for both the uplink (UL) and downlink (DL). Typical URLLC requirements for a single packet transmission are a block error rate (BLER) of 1E-5 for a 32-byte packet size with a user plane latency of 1 ms.

[0028] From a physical layer perspective, there are several possible ways to improve reliability. Current scope for improving reliability includes defining a separate CQI table for URLLC, a more compact DCI (downlink control information) format, PDCCH repetition, etc. However, as NR becomes more stable and more developed (a key requirement for NR URLLC), the scope for achieving ultra-high reliability may expand. Specific use cases for NR URLLC in Release 15 include augmented reality / virtual reality (AR / VR), eHealth, eSafety, and mission-critical applications.

[0029] Furthermore, technology enhancements targeted at NR URLLC target latency improvement and reliability enhancement. Technology enhancements for latency improvement include configurable numerology, non-slot-based scheduling with flexible mapping, grant-free (configured grant) uplink, slot-level repetition of data channels, and downlink preemption. Preemption means that a transmission for which resources have already been allocated is aborted and the already allocated resources are used for another transmission requested later with smaller latency / higher priority requirements. Thus, an already granted transmission is preempted by a later transmission. Preemption applies regardless of service type. For example, a transmission of service type A (URLLC) can be preempted by a transmission of service type B (e.g., eMBB). Technology enhancements related to reliability improvement include dedicated CQI / MCS tables for a target BLER of 1E-5.

[0030] The mMTC (Massive Machine Type Communication) use case is characterized by a very large number of connected devices transmitting relatively small amounts of data that are generally latency sensitive. The devices are required to be low cost and have extremely long battery life. From an NR perspective, utilizing very narrow bandwidth portions is one possible solution to achieve power savings from the UE perspective, enabling long battery life.

[0031] As mentioned above, it is expected that the reliability spectrum in NR will expand. One key requirement in all cases, especially for URLLC and mMTC, is high or ultra-high reliability. Several mechanisms can be considered to improve reliability from a radio perspective and a network perspective. In general, there are several key areas that can help improve reliability. These areas include compact control channel information, data channel / control channel repetition, and diversity related to the frequency, time, and / or spatial domains. These areas are generally applicable to reliability, regardless of the specific communication scenario.

[0032] For NR URLLC, further use cases with more stringent requirements have been identified, such as factory automation, transportation, and power distribution. The more stringent requirements include higher reliability (up to 10 times faster) depending on the use case. -6 level), higher availability, packet sizes up to 256 bytes, time synchronization on the order of a few microseconds (1 microsecond to a few microseconds depending on the frequency range), and low latency on the order of 0.5-1 ms, with a target user plane latency of 0.5 ms in particular.

[0033] Furthermore, for NR URLLC, several technical enhancements have been identified from the physical layer perspective. In particular, enhancements related to the PDCCH (Physical Downlink Control Channel) include compact DCI, PDCCH repetition, and increased PDCCH monitoring. Also, enhancements related to the UCI (Uplink Control Information) include enhanced Hybrid Automatic Repeat Request (HARQ) and enhanced CSI feedback. Also, PUSCH enhancements related to minislot-level hopping and enhanced retransmission / repetition have been recognized. The term "minislot" refers to a TTI (Transmission Time Interval) that contains fewer symbols than a slot (a slot contains 14 symbols).

[0034] In slot-based scheduling or allocation, a slot corresponds to the timing granularity (TTI - Transmission Time Interval) of the scheduling allocation. Generally, the TTI determines the timing granularity for the scheduling allocation. One TTI is the time interval during which a given signal is mapped to the physical layer. For example, conventionally, the length of the TTI can vary from 14 symbols (slot-based scheduling) to 2 symbols (non-slot-based scheduling). Downlink (DL) transmission and uplink (UL) transmission are defined to be organized into a frame (with a duration of 10 ms) consisting of 10 subframes (with a duration of 1 ms). In slot-based transmission, a subframe is further divided into slots, and the number of slots is defined by the numerology / subcarrier spacing. The defined values range from 10 slots / frame (1 slot / subframe) when the subcarrier spacing is 15 kHz to 80 slots / frame (8 slots / subframe) when the subcarrier spacing is 120 kHz. The number of OFDM symbols per slot is 14 for the normal cyclic prefix and 12 for the extended cyclic prefix (see Sections 4.1 (General Frame Structure), 4.2 (Numerology), 4.3.1 (Frames and Subframes), and 4.3.2 (Slots) of Non-Patent Document 5). However, the allocation of time resources for transmission may also be non-slot-based. In particular, the TTI in non-slot-based allocation can correspond to a mini-slot instead of a slot. That is, one or more mini-slots can be allocated for the required transmission of data / control signaling. In non-slot-based allocation, the minimum length of the TTI can be, for example, 1 or 2 OFDM symbols.

[0035] <QoS Control> The 5G QoS (Quality of Service) model is based on QoS flows and supports both QoS flows that require a guaranteed flow bit rate (GBR QoS flows) and QoS flows that do not require a guaranteed flow bit rate (non-GBR QoS flows). At the NAS level, QoS flows are therefore the finest granularity of QoS differentiation in a PDU session. Within a PDU session, QoS flows are identified by a QoS Flow ID (QFI) carried in the encapsulation header over the NG-U interface.

[0036] The 5GC establishes one or more PDU sessions for each UE. The NG-RAN establishes at least one Data Radio Bearer (DRB) for each UE along with the PDU session, and can then configure additional DRBs for the QoS flows of that PDU session (as determined by the NG-RAN, e.g., as described above with reference to Figure 3). The NG-RAN maps packets belonging to different PDU sessions to different DRBs. NAS-level packet filters in the UE and 5GC associate UL and DL packets with QoS flows, and AS-level mapping rules in the UE and NG-RAN associate UL and DL QoS flows with DRBs.

[0037] Figure 5 shows the 5G NR non-roaming reference architecture (see Section 4.23 of 3GPP TS 365-6491). Application Functions (AFs) (e.g., external application servers handling 5G services exemplarily described in Figure 4) interact with the 3GPP core network to provide services. For example, they support application influence on traffic routing, access Network Exposure Functions (NEFs), and interact with a policy framework (see Policy Control Function (PCF)) for policy control (e.g., QoS control). Based on the operator's deployment, application functions (AFs) deemed trusted by the operator can be allowed to interact directly with associated network functions. Application Functions (AFs) not permitted by the operator to directly access network functions interact with associated network functions using an external exposure framework via the NEF.

[0038] Figure 5 shows further functional units of the 5G architecture: Network Slice Selection Function (NSSF), Network Repository Function (NRF), Unified Data Management (UDM), Authentication Server Function (AUSF), Access and Mobility Management Function (AMF), Session Management Function (SMF), and Data Network (DN) (e.g., operator services, internet access, or third-party services). All or part of the core network functions and application services may be located and run in a cloud computing environment.

[0039] Therefore, in the present disclosure, there is provided an application server (e.g., AF in a 5G architecture) that, during operation, transmits a request including QoS requirements for at least one of URLLC services, eMBB services, and mMTC services to at least one of the functions of the 5GC (e.g., NEF, AMF, SMF, PCF, UPF, etc.), and a transmitter that establishes a PDU session including a radio bearer between the gNodeB and the UE in accordance with the QoS requirements, and a control circuit that executes a service using the established PDU session during operation.

[0040] In LTE and NR, the terminal is called a user equipment (UE). This can be a mobile device or a communication device such as a radio telephone having the functions of a user equipment, a smartphone, a tablet terminal, a USB (Universal Serial Bus) stick, etc. However, the term mobile device is not limited to this, and generally, a repeater may also have the functions of such a mobile device, and the mobile device may function as a repeater.

[0041] The base station is a network node or a scheduling node, and for example, forms a part of the network for providing services to the terminal. The base station is a network node that provides wireless access to the terminal.

[0042] <RRC state> In wireless communication systems, including NR, devices or communication devices (e.g., UEs) can be in different states depending on traffic activity. In NR, devices can be in one of three RRC states: RRC_IDLE, RRC_CONNECTED, and RRC_INACTIVE. The first two RRC states, RRC_IDLE and RRC_CONNECTED, are similar to LTE, but RRC_INACTIVE is a new state introduced in NR that does not exist in the original LTE design. There are also core network states, CN_IDLE and CN_CONNECTED, depending on whether the device has established a connection with the core network.

[0043] In RRC_IDLE, no RRC context (i.e., parameters required for communication between the device and the network) exists in the radio access network and the device does not belong to a specific cell. From the core network's perspective, the device is in CN_IDLE state. To conserve battery power, the device sleeps most of the time, so no data transfer takes place. In the downlink, an idle device periodically wakes up to receive paging messages from the network (if present). Mobility is handled by the device through cell reselection. Uplink synchronization is not maintained, so the only uplink transmission activity that is possible is random access (e.g., to transition to connected state). As part of the transition to connected state, an RRC context is established in both the device and the network.

[0044] In RRC_CONNECTED, the RRC context is established and all parameters required for communication between the device and the radio access network are known to both entities. From the core network's perspective, the device is in the CN_CONNECTED state. The cell to which the device belongs is known, and the C-RNTI (Cell Radio-Network Temporary Identifier), a device identifier used for device-to-network signaling purposes, is configured. The connected state is intended for data transfer to and from the device, but discontinuous reception (DRX) can be configured to reduce device power consumption. In the connected state, the RRC context is established in the gNB, so ending DRX and starting data transmission and reception is relatively fast because no connection establishment with associated signaling is required. Mobility is managed by the radio access network; the device provides measurements of neighboring cells to the network, and the network commands the device to perform handover if necessary. Uplink time alignment may or may not exist, but must be established and maintained using random access for data transmission.

[0045] LTE supports only the idle and connected states. In practice, it is common for devices to use the idle state as their primary sleep state to reduce power consumption. However, frequent transmission of small packets is common in many smartphone applications, resulting in a large number of idle-to-active transitions in the core network. These transitions are costly in terms of signaling load and associated delay. Therefore, to reduce the signaling load and generally reduce delay, NR defines a third state, the RRC_INACTIVE state.

[0046] In RRC_INACTIVE, the RRC context is maintained in both the device and the gNB. The core network connection is also maintained, i.e., the device is in CN_CONNECTED state from the core network perspective. Therefore, the transition to the connected state for data transfer is fast. No core network signaling is required. The RRC context already exists in the network, and the transition from idle to active can be handled within the radio access network. At the same time, the device can sleep in a similar way to when it is in idle state, and mobility is handled through cell reselection, i.e., without network involvement. Therefore, the mobility of the communication device or communication equipment is device-controlled, not network-controlled, and the communication equipment can contact the network by random access. Therefore, RRC_INACTIVE can be considered a hybrid of the idle and connected states (see 3GPP TS 365.1-365.3 for further details).

[0047] <Non-terrestrial network (NTN)> In 3GPP, NR-based operation in NTNs (non-terrestrial networks) has been considered and described (see, for example, Non-Patent Document 8 and Non-Patent Document 9).

[0048] Because space / airborne vehicles have wide service coverage and are less vulnerable to physical attacks and natural disasters, NTNs can facilitate the deployment of NR services in areas where terrestrial NR networks cannot cover (e.g., isolated or remote areas, on aircraft or ships) and in unserved areas (e.g., suburban and rural areas). Furthermore, NTNs can enhance the reliability of NR services by providing service continuity to passengers on moving platforms and ensuring service availability everywhere, especially for critical communications.

[0049] These benefits relate to either standalone non-terrestrial networks or integrated terrestrial and non-terrestrial networks and can impact coverage, user bandwidth, system capacity, service reliability and availability.

[0050] A non-terrestrial network refers to a network or part of a network that uses RF resources onboard a satellite, for example. An NTN typically comprises the following system elements: an NTN terminal (which refers to a 3GPP UE or a terminal specific to the satellite system if the satellite does not directly serve 3GPP UEs), a service link which refers to the radio link between the user equipment and the space / airborne platform, an airborne platform carrying a payload, a gateway connecting the space / airborne platform to the core network, and a feeder link which refers to the radio link between the gateway and the space / airborne platform.

[0051] Figure 6 shows a non-terrestrial network scenario, in which transmission between terminals (UEs) is via a remote radio device including a satellite and an NTN gateway. The gateway is equipped with a gNB as a scheduling device. The satellite's payload performs frequency conversion and radio frequency amplification in both the uplink and downlink directions. The satellite therefore replicates the NR radio interface from the feeder link (between the NTN gateway and the satellite) to the service link (between the satellite and the UE) or vice versa. A satellite with this configuration is called a transparent relay satellite.

[0052] Figure 7 shows a non-terrestrial network scenario, where transmissions between terminals (UEs) are carried out via satellites with gNBs as scheduling devices. Satellites in this configuration are called regenerative satellites.

[0053] NTNs can consider various types of platforms, including satellites and UAS (Unmanned Aerial System) platforms, examples of which are shown in Table 1 (this table corresponds to Table 4.1-1 in Non-Patent Document 9; see also Section 4.1 "Non-Terrestrial Networks overview" in Non-Patent Document 9). [Table 1]

[0054] Because LEO, MEO, and HEO satellites do not maintain fixed positions relative to a point on Earth, the satellite beams corresponding to the cells or PCIs (Physical Cell IDs) or SSB (Synchronization Signal Block) beams of an NR radio system may move around the Earth.

[0055] Regarding the mapping between satellite beams, NR cells, and NR SSB beams, different deployment options can be considered, for example, option a and option b shown in Figures 8 and 9. According to deployment option a shown in Figure 8, one cell (corresponding to a PCI) has multiple satellite beams (e.g., the same PCI for multiple satellite beams), whereas according to deployment option b shown in Figure 9, one cell corresponds to one satellite beam (there is one PCI per satellite beam).

[0056] A satellite beam can consist of one or more SSB beams. For example, one satellite beam can be mapped to one SSB beam, e.g., there is a one-to-one correspondence between the satellite beam and the SSB beam. In this case, the beam used to transmit the NR synchronization signal block is referred to as the SSB beam. One NR cell (PCI) can have up to L SSB beams, where L can be 4, 8, or 64 depending on the band. An SSB beam can be used as a reference beam for beam management in NR.

[0057] An NTN scenario that provides cells that move continuously across the Earth (e.g., a LEO-, MEO-, or HEO-based NTN) is called a geo-mobile cell scenario. The geo-mobile cell scenario is illustrated in Figure 10. The continuous cell movement across the Earth is due to the satellite beams being fixed relative to the NTN platform. Thus, according to deployment options a and b described above, the footprint of the cell corresponding to several satellite beams or one satellite beam moves across the Earth's surface as the NTN platform (e.g., the LEO satellite shown in Figure 10) moves.

[0058] Information about the satellite's orbit is contained in ephemeris data (or "satellite ephemeris data"). There are various ways to represent ephemeris data; one possible way is to use orbital parameters such as semi-major axis, eccentricity, inclination, right ascension of ascending node, argument of periapsis, mean anomaly at a reference point in time, and epoch. The first five parameters allow for determining the orbital plane (orbital plane parameters), while the remaining two parameters are used to determine the exact satellite position at a given time (satellite-level parameters). The orbital plane parameters and satellite-level parameters are summarized in Table 2 and shown in Figure 11 (see also Section 7.3.6.1 "Representation of Complete Ephemeris Data" in Non-Patent Document 9). Another possible option is to provide the satellite position coordinates (x, y, z), velocity vector (vx, vy, vz), and reference time. [Table 2]

[0059] Therefore, the representation requires seven parameters (e.g., double-precision floating-point numbers) and possibly some overhead. In an NTN system, several satellites may share a common orbital plane. In such cases, to reduce the amount of data, some ephemeris data can be provided for an orbital plane rather than for a single satellite. The ephemeris data for each orbital plane can be stored in the UE or in the UE's SIM (Subscriber Identity Module).

[0060] However, in networks with a large number of satellites, the size of the ephemeris data can become significant. Therefore, rather than storing the ephemeris data, at least a portion of the ephemeris data can be transmitted from the gNB.

[0061] For example, satellite-level orbital parameters for all satellites that can serve the UE can be stored in the UE or SIM, and the ephemeris data for each satellite is linked to a satellite ID or satellite index. In this case, the satellite ID or satellite index of the serving satellite can be broadcast in the system information so that the UE can find the corresponding ephemeris data in the UE's SIM or storage device.

[0062] Alternatively, the satellite-level orbital parameters of the serving satellite can be broadcast in the system information, and the UE derives the position coordinates of the serving satellite. Ephemeris data of neighboring satellites can also be provided to the UE via system information or dedicated RRC signaling. If the reference orbital plane parameters are provided to the UE or SIM, it is sufficient to broadcast the average anomaly value at the reference time instant, and the epoch does not need to be broadcast to the UE, thus reducing overhead.

[0063] The high speed of satellite movement relative to a fixed location on Earth may result in frequent SSB switching in deployment option a, or frequent handovers (HO) in deployment option b. For example, in the reference scenario, the NTN LEO cell has a ground diameter of 50 km and a satellite ground speed of 7.56 km / s. In this case, a stationary UE needs to perform HO every 6.61 seconds.

[0064] In NR terrestrial networks, a target cell and / or target SSB beam is typically selected based on measuring reference signals (RS) from neighboring cells / beams and reporting the measurements (e.g., reference signal received power (RSRP)) to the gNB. The target cell or target SSB beam is then indicated to the UE, e.g., via RRC signaling (in the case of HO) or MAC / DCI signaling (in the case of beam switching).

[0065] However, if the same RS measurement-based mechanism for SSB beam switching or HO is also used for NTN mobile cell scenarios, the signaling overhead and UE power consumption may increase as a result of frequently measuring and reporting reference signals (RS) to indicate the cell or SSB beam. Furthermore, due to the large distance between the UE and the satellite or NTN platform, long propagation delays may cause data transmission to be interrupted during HO and beam switching.

[0066] The present disclosure provides techniques for determining a serving cell and a serving beam in a non-terrestrial network such as an NR NTN, and information about the UE's location and the movement status of terrestrial cells / beams determines the serving cell and / or serving beam and the execution timing for switching to the serving cell or serving beam as a target cell / target beam.

[0067] 12 provides a user equipment 1260 and a base station 1210. The user equipment and the base station communicate with each other via a wireless channel in a wireless communication system. For example, the user equipment may be an NR user equipment, and the base station may be a network node or scheduling node such as an NR gNB, particularly a gNB in ​​an NTN NR system. However, the present disclosure is not limited to 3GPP NR and may also be applied to other wireless or cellular systems such as NTN.

[0068] As shown in FIG. 12, the UE 1260 includes a transceiver 1270 (or a "UE transceiver" to distinguish it from a transceiver in another type of communication device) and circuitry 1280 ("UE circuitry") such as processing and control circuitry. For example, the UE circuitry 1280 includes a satellite beam switching circuit 1285. FIG. 13 shows an exemplary UE satellite beam switching circuit 1285, which includes a satellite beam switching time determination circuit 1386 and a satellite beam switching control circuit 1387.

[0069] As further shown in Figure 12, the base station 1210 includes a transceiver 1220 ("base station transceiver") and circuitry 1230 ("base station circuitry"). For example, the base station circuitry 1230 may include satellite beam switching circuitry 1235. The exemplary satellite beam switching circuitry shown in Figure 14 includes at least one of a satellite beam switching time determination circuit 1436 and a satellite beam switching control circuit 1437.

[0070] In some embodiments, the UE transceiver 1270, during operation, receives coverage area information indicating the coverage area of ​​at least one candidate satellite beam relative to the satellite position of at least one satellite that respectively generates the at least one candidate satellite beam.

[0071] For example, a first candidate satellite transmits a first beam or beams, and a second satellite transmits a second beam or beams that are different from the first beam transmitted by the first satellite.

[0072] The UE circuit 1280 the received coverage area information, and Ephemeris data for at least one satellite that generates at least one candidate satellite beam; and the location of the user equipment; and For example, the UE circuitry 1280 selects a target satellite beam from among the candidate satellite beams by performing a calculation based on the coverage area information, the ephemeris data, and the UE's location. Furthermore, the UE circuitry 1280 determines (e.g., derives or calculates) a switch timing for switching to the target satellite beam based on the coverage area information, the ephemeris data, and the UE's location.

[0073] In operation, the UE circuitry 1280 controls the UE transceiver 1270 to perform a switch to a determined or selected target satellite beam at a determined switch timing, such that the UE switches to the determined target satellite beam at the determined switch timing.

[0074] Corresponding to the above-mentioned UE, a communication method executed by the UE is provided. As shown in FIG. 15, the communication method (abbreviated as "UE method") includes step S1510 of receiving coverage area information indicating a coverage area of ​​at least one candidate satellite beam relative to a satellite position of at least one satellite that respectively generates the at least one candidate satellite beam. For example, the coverage area information is received from a base station. The UE method includes step S1520 of determining a target satellite beam to switch to from the at least one candidate satellite beam and a switching timing for switching to the target satellite beam. In this case, the target satellite beam and the switching timing are determined based on the received coverage area information, ephemeris data of at least one satellite that generates the at least one candidate satellite beam, and the position of the UE. The UE method further includes step S1530 of the UE switching to the determined target satellite beam at the determined switching timing.

[0075] The UE switches from the source serving beam to the determined target satellite beam. For example, the UE 1260 communicates with the base station 1210 (e.g., the "source base station") via the source serving beam in the source cell served by the base station. The source serving beam is the satellite beam through which the UE and the base station communicate before switching satellite beams. When switching to the target satellite beam, the UE initiates communication with the same base station (in the case of a serving beam switch, where the target serving cell is the same cell as the source serving cell) or the target base station (in the case of a handover) via the target satellite beam, and communicates via the target satellite beam after the determined switching timing. Depending on the type of signaling and the definition of the switching timing, such as communication regarding how the switching timing is defined, the UE's communication via the target satellite beam can already begin before the switching timing (e.g., by transmitting a RACH preamble). In general, the source serving cell may be a cell of an NTN (e.g., the source serving beam is a satellite beam) or a cell of a terrestrial base station.

[0076] As described above and shown in Figures 8 and 9, a single serving cell (PCI) may correspond to multiple satellite beams (deployment option a in Figure 8), or there may be a one-to-one correspondence between serving cells and satellites (option b in Figure 9). In this disclosure, switching a satellite beam, or switching to a target beam, refers to both switching to another satellite beam within the same cell and switching to another cell (e.g., handover).

[0077] According to the above-described embodiments of the UE and UE method, the UE receives coverage area information, which provides the UE with information about how terrestrial cells or beam areas are defined (e.g., footprint coverage), typically including at least one of the cell size and shape and, possibly, the cell's location relative to satellite coordinates that can be derived from ephemeris data. Furthermore, the satellite ephemeris data provides information about how the terrestrial cells or beams are moving. Furthermore, assuming the UE knows its location, e.g., via a Global Navigation Satellite System (GNSS), the UE knows which terrestrial cells or beam areas cover the UE's location at any given time. Therefore, the UE determines the serving beam and, possibly, the serving cell as the target beam or cell to switch to based on the information about how the terrestrial cells or beams are defined and how they are moving, and its knowledge of its location.

[0078] In some embodiments, the coverage area information is received in system information. For example, the coverage area information, e.g., information on how terrestrial cells or beams are defined, is broadcast by SIB (System Information Block). In this case, the UE can use the coverage area information in either IDLE mode, INACTIVE mode, or CONNECTED mode. Thus, a mechanism is provided that can be used not only for IDLE and INACTIVE UEs, but also for CONNECTED UEs. Alternatively, the coverage information can be received in UE-specific RRC signaling and made available to CONNECTED UEs.

[0079] For IDLE UEs and INACTIVE UEs, the selection of the target serving cell and / or target beam does not need to be known to the base station. However, for CONNECTED UEs, the UE 1260 and the base station 1210 should have the same knowledge. For example, when communication occurs over a physical uplink channel and / or a downlink control channel and / or a shared channel, such common knowledge may be necessary so that the base station knows when to stop communication with the UE. This common knowledge can be provided by the UE reporting its location information to the base station 1210, for example, periodically or aperiodically. Thus, in some embodiments, the UE transceiver 1270, upon operation, transmits a location report indicating the UE's location. Alternatively, or in addition, the UE can directly report the switch timing and possibly the target satellite beam (e.g., the selected cell or beam). Thus, the UE transceiver 1270, upon operation, transmits an indication of the determined target satellite beam and the determined switch timing. If the UE directly transmits the switch timing and possibly the target satellite beam to the base station, the gNB can avoid processing to determine the switch timing and possibly the target beam.

[0080] It should be further noted that the present disclosure is not limited to the UE receiving the coverage area information. For example, the coverage area information may be stored in a memory of the UE, such as a read-only memory (ROM), or in the UE's SIM, thereby eliminating the need to broadcast the coverage area information via system information. However, considering the large amount of data to be stored, the present disclosure also includes the case where a portion of the coverage area information is stored in the UE or SIM, and the remaining portion of the coverage information is received in broadcast, similar to the discussion regarding satellite ephemeris data above.

[0081] Furthermore, the ephemeris data can be broadcast through system information, such as the SIB, or stored in the UE's internal storage or SIM. For example, the ephemeris data, or at least a portion of the ephemeris data, is received by the UE in the SIB or alternatively in RRC signaling. As another example, the UE can include a SIM interface that, in operation, receives the ephemeris data, or a stored portion of the ephemeris data, from a SIM that stores the ephemeris data. The ephemeris data can be broadcast in the system information in addition to or without coverage area information (i.e., the coverage area information is stored in the UE / SIM). The ephemeris data can also include coverage area information.

[0082] As described above, satellite ephemeris data can be classified into orbital plane parameters and satellite-level parameters. For example, the ephemeris data is broadcast to the UE via the SIB, but to reduce broadcast overhead, the SIB can provide parameters related to a small number of neighboring satellites as satellites for generating candidate satellite beams.

[0083] In operation, the transceiver 1220 of the base station 1210 communicating with the UE of the above-described embodiment transmits coverage area information indicating the coverage area of ​​at least one candidate satellite beam relative to the satellite position of at least one satellite that respectively generates the at least one candidate satellite beam, to, for example, the UE 1260. In operation, the base station transceiver 1220 further receives, from, for example, the UE 1260, a location report indicating the location of the UE 1260 or a target satellite beam among the at least one candidate satellite beam and an instruction for when the UE should switch to the target satellite beam.

[0084] In operation, the base station circuitry 1230 determines a target satellite beam and switching timing based on received instruction information or based on transmitted coverage area information, ephemeris data of at least one satellite generating at least one candidate satellite beam, and the location of the UE indicated by a received position report.

[0085] Furthermore, the base station circuit 1230 terminates communication with the UE via the source beam at the determined switching timing.

[0086] In the case of handover, the base station terminates communication with the UE via the source serving beam, and the UE starts communication with another base station (target base station) that serves the target cell via the target satellite beam. In the case of beam switching within the same serving cell, the base station terminates communication with the UE via the source beam and starts communication with the UE via the target satellite beam.

[0087] For example, the UE performs a handover to another base station, in which case the base station terminates communication with the UE and stops performing downlink transmissions and receiving uplink transmissions by the switching timing, e.g., before or at the switching timing. Alternatively, for example, if the target satellite beam is a serving beam of the same cell, the base station switches the UE from the source serving beam with which communication is currently taking place to the target serving beam. For example, the base station terminates communication (uplink and downlink transmissions) with the UE via the source beam and starts communication with the UE via the target satellite beam.

[0088] Corresponding to the above description of the base station, a communication method (abbreviated as "base station method") performed by a base station is provided, and FIG. 16 illustrates the method. The method includes a step S1610 of transmitting coverage area information indicating the coverage area of ​​at least one candidate satellite beam relative to the satellite position of at least one satellite that generates the at least one candidate satellite beam, respectively. The base station method further includes a step S1615 of receiving a location report indicating the location of a user equipment (UE), or a target satellite beam among the at least one candidate satellite beam, and instruction information for a switching timing for the UE to switch to the target satellite beam. The base station method further includes a step S1620 of determining the target satellite beam and the switching timing. The target satellite beam and the switching timing are determined based on the received instruction information, or based on the transmitted coverage area information, ephemeris data of at least one satellite that generates the at least one candidate satellite beam, and the location of the UE indicated by the received location report. The base station method includes a step S1630 of terminating communication with the UE via the source serving beam at the determined switching timing.

[0089] The embodiments and examples provided by the present disclosure should be understood to refer to both base stations and UEs, as well as to devices (e.g., base stations or UEs), and methods performed by the corresponding devices. For example, a base station may transmit one or both of coverage area information and ephemeris data in system information or RRC signaling, unless otherwise specified or the context indicates otherwise.

[0090] Furthermore, as previously mentioned, when the UE is in CONNECTED mode, it is desirable for the UE and the base station to have a common understanding of satellite beam switching, e.g., target satellite beam switching and switching timing.

[0091] However, for IDLE UE and INACTIVE UE, the selection of the target satellite beam, such as the serving cell or serving beam, does not need to be known to the base station. When communicating with a UE in IDLE mode or INACTIVE mode, it may be sufficient for the base station to transmit coverage area information (corresponding to step S1610 in FIG. 16) and possibly ephemeris data. On the other hand, when the UE to be switched is in IDLE mode or INACTIVE mode, steps S1615 to S1630 can be omitted. For this reason, the satellite beam switching time determination circuit 1436 and the satellite beam switching control circuit S1437 are shown with dashed lines in FIG. 14.

[0092] In the above-mentioned embodiment, a first scheme of the present disclosure is provided, in which the UE determines the target satellite beam to switch to and the timing of switching based on coverage area information, ephemeris data, and the UE's location (all three pieces of information are available to the UE).

[0093] However, in addition to the first scheme described above, the present disclosure provides a second scheme described below, in which the UE switches to a target satellite beam based on indication information of one or more satellite beams to be switched to that is signaled to the UE.

[0094] Thus, in some embodiments, UE transceiver 1270, in operation, transmits a position report indicating the position of UE 1260 and receives UE-specific signaling indicating at least one target satellite beam and at least one corresponding switch timing for switching to the at least one target satellite beam. UE circuitry 1280, in operation, controls the transceiver to perform a switch to the at least one target satellite beam at the at least one corresponding switch timing indicated in the UE-specific signaling.

[0095] Correspondingly, in operation, the base station transceiver 1220 receives a position report indicating a position of the UE and transmits UE-specific signaling indicating at least one target satellite beam and at least one corresponding switch timing for the UE to switch to the at least one target satellite beam, where the at least one target satellite beam is a satellite beam among the at least one candidate satellite beam and the at least one corresponding switch timing are determined (e.g., calculated and / or selected) by the base station circuitry 1230 based on coverage area information indicating a coverage area of ​​the at least one candidate satellite beam relative to a satellite position of at least one satellite that respectively generates the at least one candidate satellite beam, ephemeris data of the at least one satellite that generates the at least one candidate satellite beam, and the position of the user equipment indicated in the received position report.

[0096] Corresponding to the UE and base station of the second scheme disclosed above, embodiments of a communication method for a UE ("UE method") and a communication method for a base station (base station method) are provided, and steps of these methods are shown in Figures 17 and 18.

[0097] 17, the UE method includes step S1715 of transmitting a UE location report indicating the location of the UE. The UE method further includes step S1725 of receiving UE-specific signaling indicating at least one target satellite beam and at least one corresponding switch timing for switching to the at least one target satellite beam, and step S1730 of switching to the at least one target satellite beam at the at least one corresponding switch timing indicated in the UE-specific signaling.

[0098] 18, the base station method includes step S1815 of receiving a location report indicating a location of a user equipment (UE). The base station method further includes step S1820 of determining at least one target satellite beam of the at least one candidate satellite beam and at least one corresponding switch timing for the UE to switch to the at least one target satellite beam based on coverage area information indicating a coverage area of ​​the at least one candidate satellite beam relative to a satellite position of at least one satellite that respectively generates the at least one candidate satellite beam, ephemeris data of the at least one satellite that generates the at least one candidate satellite beam, and the location of the user equipment indicated in the received location report. Furthermore, the method includes step S1825 of transmitting UE-specific signaling indicating the at least one target satellite beam and at least one corresponding switch timing for the UE to switch to the at least one target satellite beam.

[0099] In addition to the steps shown in FIG. 18, the base station method may include a step of terminating communication with the UE at the determined switching timing, for example, switching the UE to another serving beam by terminating communication on the source beam and starting communication on a target beam, which may include a beam of the same serving cell.

[0100] As described above, in the second scheme, the UE is provided with UE-specific signaling indicating one or more target satellite beams and one or more switching timings. For example, the UE is provided with a list of one or more serving cells and / or serving beams with associated execution timings (e.g., switching timings) after the UE reports its location (e.g., based on GNSS measurements). Based on the instruction information, such as the list of target satellite beams and corresponding timings, the UE switches to the serving cell / serving beam at the indicated timings.

[0101] A base station (e.g., gNB) can store information about how terrestrial cell / beam areas are defined (e.g., coverage area information) and satellite ephemeris data (which indicates how the satellites, and therefore the terrestrial cells / beams, are moving). After the UE reports its location, the gNB knows which terrestrial cell / beam area covers the UE's location at which time and can determine a target satellite beam to switch to and the associated switch timing. For example, UE-specific RRC signaling can be used as UE-specific signaling regarding the target beam and switch timing.

[0102] For example, if there is a one-to-one correspondence between satellite beams and serving cells, the target satellite beam can be indicated by the cell ID (e.g., PCI) of the serving cell. Furthermore, in the case of intra-cell beam switching, the target satellite beam can be indicated by, for example, indicating the SSB (synchronization signal block) index.

[0103] In some examples, the UE-specific signaling indicates multiple target satellite beams and multiple corresponding switching timings. Thus, the UE-specific signaling may include a list including multiple entries. Each entry may include a target satellite beam (represented by one or both of cell identification information, such as a PCI, and beam designation information) and a switching timing or execution timing for switching to the target satellite beam.

[0104] In the second scheme, the base station determines and provides a list of one or more target beams / target cells and their associated switching timings, thereby enabling the base station to determine a future target cell / target beam plan. For example, if there are multiple target beam switching timings, the UE can perform multiple switches (handovers or beam switching) without needing new indication information of the next target beam or target cell for each handover or switching process.

[0105] Below, we provide some examples of how terrestrial cells or beam areas corresponding to the footprint coverage of satellite beams on the Earth are defined, which are shown in Figures 19 to 21. The following embodiments and examples can be combined with the first and second schemes described above.

[0106] As one option shown in FIG. 19, the coverage area information includes, for each of at least one candidate satellite beam, a satellite beam direction and a radius or diameter of the coverage area, e.g., a radius or diameter on the Earth (e.g., footprint coverage), optionally provided in addition to a PCI and / or SSB index corresponding to each candidate satellite beam.

[0107] The UE (first scheme) and / or the base station (e.g., second scheme) can then select a satellite beam whose footprint covers the UE's location.

[0108] A UE may be located in an overlapping area, such as the coverage areas of two adjacent satellite beams (e.g., cell or SSB beams), in which case the UE is covered by multiple footprint coverage, e.g., the two overlapping footprints shown in FIG. 19. In such cases, the target satellite beam may be determined by a rule, possibly based on the UE's identity. For example, a UE with an even ID may be served by a satellite beam corresponding to a lower PCI and / or lower SSB index, and a UE with an odd ID may be served by a higher cell ID or SSB index, or vice versa. For example, such a rule may be defined in a standard that may facilitate a balanced distribution of UEs among serving beams or serving cells.

[0109] In a second option shown in FIG. 20 , the coverage area information includes polygons that define coverage areas without overlapping. For example, each of the candidate satellite beams corresponds to a polygon or shape, and the polygons representing the different coverage areas do not overlap. For example, the coverage area information can include terrestrial cell / beam areas defined by shapes such as rectangles or hexagons, and the shapes do not overlap in the different coverage areas. This shape information can be provided in addition to the PCI and / or SSB index that correspond to each of the candidate satellite beams. The UE (e.g., UE circuitry 1280) can then select the terrestrial area that covers the UE's location as a target satellite beam, e.g., a serving cell or beam.

[0110] For example, the polygon may be described using a reference point (such as a corner or center) (which may be relative to the current satellite position obtained from the ephemeris data) and the length of the polygon's sides or another indication of the polygon's size. As another example, the polygon may be described using the coordinates of all of the polygon's corners relative to the satellite position.

[0111] According to this second option, no additional rules (such as the UE ID based rules described above with respect to the first option) are needed, as the shapes representing the coverage areas of different candidate satellite beams do not overlap.

[0112] In a third option, the coverage area information includes a center and a radius of the coverage area, as shown in Figure 21. The UE (or UE circuitry 1280) may select the satellite beam whose center is closest or closest (e.g., has the smallest distance) to the UE's location if the in-coverage distance is met, which may be the radius of the coverage area, as shown in Figure 21. Otherwise, if the in-coverage distance is not met for any satellite beam or cell, the UE is out-of-coverage.

[0113] The third option, which provides the coverage area center and radius, and the first option, which is based on the satellite beam direction and coverage area radius, are somewhat similar in terms of the parameters signaled. For example, because the beam center can be derived from the beam direction and the radius can be derived from the diameter, the same pair of values ​​can be signaled in both options, or the radius can be provided in both options. Therefore, the actual parameters signaled in the first and third options are interchangeable. However, the difference between the first and third options is that in the third option, the UE selects the satellite beam whose footprint center is closest to the UE's location. Therefore, the target satellite beam can be unambiguously determined without additional rules, such as the ID-based rules described in connection with the first option. Furthermore, to control user distribution, a bias value can be added when the UE calculates the distance from the beam center. As a result, the line separating the two cells in Figure 21 is no longer centered (equal distance to the center point of both cells). Instead, the line can be shifted toward the beam center in a desired manner, for example, based on the bias value. The bias value may be selected based on, for example, population density or UE density within the cell.

[0114] The above definitions of coverage area information according to the first to third options may be provided for satellite positions that change over time and are derivable from ephemeris data for a given point in time, e.g., the positions of the satellite(s) generating the candidate satellite beam(s). As the satellite moves over time, the coverage area (e.g., size) may also change over time. For example, the size of the satellite beam area may be adjusted depending on the density of UEs or population density in the area covered by the satellite beam. Thus, when a satellite moves over an area of ​​the Earth with a higher population density, the coverage area, e.g., beam footprint or ground cell / beam area, may be reduced to provide smaller cells, thereby addressing the increased demand caused by more UEs needing to be served.

[0115] Figures 22 to 26 show some examples of details of signaling between the UE, source base station, and target base station in the second scheme described above, in which the target satellite beam and switching timing are determined by the base station and indicated to the UE via signaling.

[0116] Figure 22 shows a RACH-based handover from a source base station to a target base station. Steps S2215a and S2225b correspond to steps S1715 and S1725 of the UE method shown in Figure 17, and steps S2215b and S2225a correspond to steps S1815 and S1825 of the base station method shown in Figure 18. Furthermore, in step S2220, which corresponds to step S1820 of the base station method, the base station determines one subsequent target cell corresponding to the target satellite beam and an associated execution timing (e.g., switching timing) plan (which are transmitted to the UE by UE-specific RRC signaling).

[0117] After receiving the plan, the UE may still continue downlink and / or uplink traffic with the source base station before performing a handover from the source base station to the target base station serving the target cell via the target satellite beam (step S2226). In particular, in step S2228, the UE terminates uplink transmission with the source base station and transmits a preamble to the target base station. The UE receives the random access response transmitted by the target base station in step S2229. Then, in step S2230, the UE terminates downlink communication with the source base station and switches to the target base station serving the target cell. In the example shown in FIG. 22, the termination of downlink communication with the source base station occurs at the signaled switching timing.

[0118] In the RACH-based handover example shown in Figure 22, the indicated switching timing is after the RAR (Random Access Response corresponding to Message 2 (Msg2) of the Random Access Procedure). Therefore, the UE starts transmitting RACH preambles towards the target base station before the indicated execution or switching timing and maintains downlink reception from the source base station until the indicated switching timing.

[0119] Figure 23 shows an example of RACH-less handover, i.e., handover without using RACH. Steps corresponding to those in Figure 22 are indicated by the same reference numerals. In step S2329, the UE terminates uplink transmission with the source base station and transmits an RRCReconfigurationComplete message to the target base station before the indicated timing.

[0120] Figure 24 shows another example of signaling between a UE and a base station for handover, where corresponding steps have the same reference numbers as in Figure 23. As can be seen from Figure 24, in step S2420 of determining a plan for a target cell, all parameters required for handover to the target cell are set in the plan and the plan is signaled by RRC. In this example, in contrast to the example in Figure 23, no RRCReconfiguration signaling is exchanged during handover.

[0121] FIG. 25 illustrates an example in which, in step S2520, the base station determines a plan for multiple target cells, including associated execution (e.g., switching) timings, and UE-specific RRC signaling indicates multiple target satellite beams and associated corresponding switching timings. Similar to the above-described FIGS. 22-24, this example includes steps S2215a, b and S2225a, b for transmitting / receiving UE location reports. However, in this example, the switching timings include a first switching timing and a second switching timing. In the first switching timing, in step S2530a, the UE terminates communication (UL and DL) with the source base station and switches to the first target base station. In the second switching timing, in step S2530b, the UE terminates communication with the first target base station and switches to a second target cell served by the second target base station. Prior to the switching, the UE communicates with the source base station and the first target base station, respectively (steps S2526a, b).

[0122] The example of Figure 25 shows a handover without exchanging RRCReconfiguration messages, but this case of signaling multiple target cells can be applied not only to RACH-based handover, but also to RACH-less handover in which RRCReconfiguration messages are exchanged.

[0123] While the above-mentioned Figures 22 to 25 show the case of handover from a source cell to one or more target cells, Figure 26 shows an example of signaling between a UE and a base station for switching between beams within the same serving cell.

[0124] After transmitting / receiving the UE location report (steps S2615a, b), the base station determines a beam switching pattern for one or more CORESETs (Control Resource Sets) when determining a target satellite beam and a target switching timing in step S2620. For example, the beam switching pattern indicates one or more satellite beams as serving beams for beam switching. For example, the beam switching pattern includes one or more TCI (Transmission Configuration Indication) states with associated execution timings. Each TCI state indicates one SSB index.

[0125] A CORESET is a set of (time and frequency) resources that a UE monitors for the PDCCH. A UE can be configured with multiple CORESETs to monitor different formats of downlink control information (DCI) on different time-frequency resources. One CORESET is associated with one beam (represented by a TCI state) for the UE to monitor the PDCCH. Therefore, for different CORESETs, the beams may be different. Therefore, the beam switching patterns configured for different CORESETs may also be different. If all CORESETs are always transmitted using the same beam, the same beam switching pattern can be configured for all CORESETs.

[0126] Furthermore, to achieve a trade-off between flexibility and signaling overhead, a beam switching pattern can be configured for a subset of the CORESETs configured for a UE. For a CORESET with a beam switching pattern, beam switching is performed at the associated execution timing without additional signaling overhead. This method is expected to work well in line-of-sight (LOS) scenarios where the beam with the strongest signal strength is known from location information. However, in non-LOS scenarios, for example, due to obstruction by buildings or mountains, determining the serving beam solely based on location information may not be the strongest beam for the UE. To address such scenarios, a beam switching pattern is not configured for some CORESETs. In this case, beam switching is dynamically indicated via the MAC control element (CE) as in Release 15 NR. Furthermore, a flag indicating whether the configured beam switching pattern is enabled or disabled can be used in a CORESET with a configured beam switching pattern. If a beam switching pattern is enabled, the UE switches to the beam indicated by the pattern at the associated execution or switching timing. If the beam switching pattern is disabled, beam switching can follow the instructions of the MAC CE (Control Element), as in Release 15 NR.

[0127] Before the execution timing, the UE detects the PDCCH and / or PDSCH using the current beam, and at the execution timing, the UE starts detecting the PDCCH and / or PDSCH using the new beam or target beam for the indicated CORESET (CORESET set in the beam switching pattern).

[0128] As shown in the example of Figure 26, a beam switching pattern for downlink channels (PDCCH, PDSCH) is provided. The same or a different beam switching pattern may be configured to be applied to uplink transmissions of PUCCH and PUSCH. In case of a different uplink beam switching, e.g., a different pattern from the downlink switching pattern, a spatial relationship indication (SRI) can be used instead of TCI to indicate the uplink beam switching pattern, and the SRI can be provided in the PUCCH resource configuration.

[0129] 22 to 25, "execution timing" or "switching timing" is defined as the timing when the UE ends DL communication with the source base station and switches to the target base station. However, in the present disclosure, the switching timing is not limited to this definition. There may be other definitions of the switching timing in which other steps or operations of switching from the source cell / source base station or the target cell / target base station are performed. For example, the switching timing may be the timing of transmitting a RACH preamble to the target cell (e.g., in the case of a RACH-based handover) or the timing of transmitting an RRCReconfiguration message to the target cell (e.g., in the case of a RACH-less handover).

[0130] It is also possible for the UE and the gNB to define different switching timings, for example, the UE's switching timing is defined at the time of transmitting a RACH preamble, while the gNB's switching timing is defined at the end of DL transmission.

[0131] Furthermore, for example, in the RACH-based handover illustrated in FIG. 22, the execution timing shown, or more generally, the switch timing that can be determined by the UE and / or the base station, can take into account the maximum length of the RA response window and the possible number of attempts to transmit an RA preamble and monitor for an RA response. Thus, the UE can transmit a preamble and, if a response is not successfully received, perform one or more further preamble transmissions until the maximum number of preambles is reached. If, despite multiple attempts, no RA response is received during that time window, the UE can declare a handover failure and initiate a cell reselection procedure, e.g., as specified in NR Release 15 or Release 16.

[0132] Furthermore, although not shown in Figure 22, in a RACH-based handover, after transmitting the preamble, the UE can continue uplink communication to the source cell and switch uplink transmission to the target cell upon transmission of the RRCConfigurationComplete message.

[0133] 22 to 26, the handover execution plan or beam switching pattern is determined by the base station according to the second scheme described above. However, the first scheme, in which the target satellite beam(s) and target execution timing are derived by the UE, can be applied to any of RACH-based handover, RACH-less handover, and handover without exchanging RRC reconfiguration messages. In the first scheme, the execution timing is derived from UE location area information in conjunction with satellite ephemeris data.

[0134] Furthermore, the UE may determine not only a single target satellite beam and associated switching timing, but multiple target satellite beams and corresponding switching timings.

[0135] Furthermore, the first scheme can be applied to beam switching, for example, the UE selects a beam switching pattern based on its location, coverage area information, and ephemeris data, and indicates the beam switching pattern to the base station, possibly as a preferred beam switching pattern.

[0136] This disclosure describes switching to a target satellite beam. As previously described, the target satellite beam, like each candidate satellite beam, can have a one-to-one correspondence with the serving cell (e.g., in a one satellite beam per cell scenario, such as shown in FIG. 9). Alternatively, in a multiple satellite beam per cell scenario, such as shown in FIG. 8, the target satellite beam can have a one-to-one correspondence with a synchronization signal block (SSB) index.

[0137] According to the present disclosure, the target satellite beam and the switching timing are determined based on the location of the UE (which may be a GNSS location). For example, as shown in Figure 27, in some embodiments, the UE 2760 includes a GNSS module 2780 that determines the location of the UE by performing GNSS measurements during operation.

[0138] As described in the embodiments, the present disclosure provides a communication device comprising a communication interface and a circuit, wherein the communication interface, in operation, receives coverage area information indicating the coverage area of ​​the candidate satellite beam relative to the satellite position of a satellite that generates a candidate satellite beam or the position of a UE to be switched to, and the circuit, in operation, determines the candidate satellite beam, which is the target satellite beam to switch to, and the switching timing for switching to the target satellite beam, based on the coverage area information, ephemeris data of the satellite that generates the candidate satellite beam, and the position of the UE to be switched to.

[0139] The present disclosure further provides a communication method performed by the communication device described in the previous paragraph, the communication method including steps of receiving coverage area information and determining a target satellite beam and a switching timing for switching.

[0140] For example, according to the embodiments and schemes of the present disclosure, the communication device may be a user equipment (e.g., a first scheme) or a base station (e.g., a first scheme or a second scheme), and may be configured by the user equipment or the base station. When the communication device is a UE or configured by a UE, the location of the UE is the location of the communication device, and when the communication device is a base station or configured by a base station, the location of the UE is received by the UE, which reports the location of the UE.

[0141] The present disclosure facilitates handover and satellite beam switching, including serving beam switching. In particular, when a target satellite beam is determined based on coverage area information, ephemeris data, and the UE's location, the need for frequent measurements and measurement reporting can be alleviated. Furthermore, when measurements and reporting are not required or are performed infrequently, UE power consumption can be reduced. Furthermore, the need for a base station to select a target cell based on received measurement reports can be eliminated. Furthermore, communication interruptions during handover can be minimized. For example, the exchange of handover requests from a source base station to a target base station and the acknowledgment of the handover request can be omitted.

[0142] Furthermore, the embodiment related to the first scheme described above provides a mechanism for determining a target satellite beam and a mechanism for switching to a target satellite beam that can be applied by a UE in any of an IDLE state, an INACTIVE state, and a CONNECTED state, in particular. Therefore, the method for determining a target satellite beam does not depend on the current RRC state of the UE and does not need to be adapted to a specific state.

[0143] On the other hand, the second scheme can help reduce the processing load on the UE because the base station only needs to select the target satellite beam using the UE's location, coverage area information, and ephemeris data as inputs. Furthermore, the UE does not need to receive coverage area information and / or ephemeris data for satellite beam switching, which can reduce signaling overhead.

[0144] In some implementations of NTN communication, either the first or second method of the present disclosure can be selected, but both the first and second methods can also be combined.

[0145] One possibility is that, for example, in a scenario where the satellite beam for CONNECTED UEs is different from the satellite beam for IDLE UEs and INACTIVE UEs, IDLE UEs and INACTIVE UEs use a first scheme and CONNECTED UEs use a second scheme.

[0146] Another possibility to combine the first and second schemes is to use the first scheme for inter-cell handover and the second scheme for beam management (also called "Layer 1 (L1) mobility management"). Such a combination is particularly applicable to deployment option a (where one cell is associated with multiple beams as shown in Figure 8).

[0147] Additionally, information about the bandwidth portion used by each satellite beam can be included for scenarios where the frequency reuse factor is greater than 1. If all cells or satellite beams use the same frequency or bandwidth, the frequency reuse factor is equal to 1, and if different cells, such as adjacent cells, use different portions of the bandwidth, the frequency reuse factor is greater than 1.

[0148] Similarly, in a polarization reuse scenario, information about the polarization of each satellite beam can be included.

[0149] As described above, the inclusion of bandwidth information and / or polarization information is possible in both the first and second methods. For example, information regarding at least one of the polarization of each candidate satellite beam and the bandwidth portion of each candidate satellite beam is included in the coverage area information.

[0150] The techniques of the present disclosure can facilitate communication in NTNs, for example, in line-of-sight (LOS) scenarios, but are also applicable to non-line-of-sight (NLOS) scenarios. The techniques of the present disclosure can be combined with measurement-based schemes to facilitate a UE maintaining communication via the strongest available beam or a sufficiently strong beam (e.g., a beam with maximum or at least sufficient signal strength and / or quality). Such a combination of location-based and measurement-based schemes can be useful, for example, in NLOS scenarios, when determining a serving cell or serving beam solely based on location, coverage, and ephemeris information does not necessarily result in a sufficiently strong beam for the UE.

[0151] One example of such a combination is to determine a target satellite beam and possibly adjacent beams using the disclosed techniques for determining a target beam based on location data, coverage data, and ephemeris data. After this selection, a signal quality or signal strength measurement of the selected target satellite beam can be performed. If the beam selected using the disclosed techniques has sufficient quality, e.g., if the RSRP (Reference Signal Received Power) or RSRQ (Reference Signal Received Quality) of the selected target satellite beam is greater than a threshold, signal strength and / or signal quality measurements for adjacent satellite beams or cells can be skipped or omitted.

[0152] For example, the target satellite beam may be generated by a LEO satellite, a MEO satellite, or a HEO satellite.

[0153] Furthermore, the present disclosure is applicable to both the transparent repeater satellite case shown in Figure 6 and the regenerative repeater satellite case shown in Figure 7. Furthermore, the disclosed techniques can be applied to communication systems implementing both terrestrial and non-terrestrial networks, such as handovers from base stations with Earth-based antennas to NTN base stations with transparent repeater satellites and / or regenerative repeater satellites. For example, the target base station that generates the target satellite beam, and possibly a serving base station, such as a source base station, may be located on a satellite.

[0154] Furthermore, although this disclosure is directed to NTN communications, the disclosed techniques may also be applied in terrestrial networks, e.g., in high-velocity scenarios, provided that the UE can derive or determine its own position or movement trajectory in the first scheme, or the base station can determine or predict the UE's position or movement trajectory in the second scheme. For example, a target beam to switch to, including a beam generated by a terrestrial antenna, may be determined based on the UE's position or trajectory and coverage area information of the candidate beam(s).

[0155] The present disclosure may be implemented by software, hardware, or software cooperating with hardware. Each functional block used in the above-described embodiments may be implemented, in part or in whole, by an LSI (large-scale integrated circuit) such as an integrated circuit (IC), and each process described in each embodiment may be controlled, in part or in whole, by the same LSI or a combination of LSIs. The LSI may be formed as an individual chip, or a single chip may be formed to include some or all of the functional blocks. The LSI may include a data input / output unit coupled thereto. Depending on the degree of integration, the LSI may also be referred to as an IC, system LSI, super LSI, or ultra LSI. However, the technology for implementing an integrated circuit is not limited to LSI, and may be implemented using dedicated circuits, general-purpose processors, or dedicated processors. Furthermore, an FPGA (field programmable gate array), which can be programmed after LSI fabrication, or a reconfigurable processor, which can reconfigure the connections and settings of circuit cells arranged within the LSI, may also be used. The present disclosure may be implemented using digital or analog processing. If, as a result of advances in semiconductor technology or other derivative technologies, LSI is replaced by future integrated circuit technologies, these future integrated circuit technologies can be used to integrate functional blocks. Biotechnology can also be applied.

[0156] The present disclosure can be implemented by any kind of apparatus, device, or system having a communication capability (referred to as a communication apparatus).

[0157] A communication device may include a transceiver and processing / control circuitry. The transceiver may include and / or function as a receiver and a transmitter. As a transmitter and receiver, the transceiver may include an RF (radio frequency) module including an amplifier, an RF modulator / demodulator, etc., and one or more antennas.

[0158] Some non-limiting examples of such communications devices include telephones (e.g., mobile phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (digital audio / video players), wearable devices (e.g., wearable cameras, smart watches, tracking devices), game consoles, e-readers, telehealth / telemedicine devices, vehicles (e.g., automobiles, airplanes, ships) that provide communications capabilities, and various combinations thereof.

[0159] Communication devices are not limited to portable or mobile devices, but can also include any type of equipment, device, or system that is non-portable or fixed, such as smart home devices (e.g., appliances, lights, smart meters, control panels), vending machines, and any other "thing" in an "Internet of Things" (IoT) network.

[0160] Communication can include, for example, exchanging data through cellular systems, wireless LAN systems, satellite systems, etc., and various combinations thereof.

[0161] A communications device may include devices such as a controller or a sensor coupled to the communications device to perform the communications functions described in this disclosure. For example, a communications device may include a controller or a sensor that generates control or data signals used by the communications device to perform the communications functions of the communications device.

[0162] The communications apparatus may further include infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicate with or control apparatuses such as the apparatuses in the non-limiting examples above.

[0163] Provided is a user equipment (UE) comprising a transceiver and a circuit, wherein the transceiver, in operation, receives coverage area information indicating a coverage area of ​​at least one candidate satellite beam relative to a satellite position of at least one satellite that generates the at least one candidate satellite beam, respectively, and the circuit, in operation, determines a target satellite beam to switch to from the at least one candidate satellite beam and a switching timing for switching to the target satellite beam based on the received coverage area information, ephemeris data of the at least one satellite that generates the at least one candidate satellite beam, and the position of the user equipment, and controls the transceiver to switch to the determined target satellite beam at the determined switching timing.

[0164] For example, the coverage area information is received in the system information.

[0165] In some embodiments, the ephemeris data is received in the system information.

[0166] In some embodiments, the UE further comprises a subscriber identity module (SIM) interface that, in operation, receives ephemeris data from a SIM that stores the ephemeris data.

[0167] For example, the coverage area information includes, for each of at least one candidate satellite beam, a satellite beam direction and a radius or diameter of the coverage area, or a polygon that non-overlappingly defines the coverage area, or a center and radius of the coverage area.

[0168] In some embodiments, the transceiver, during operation, transmits a location report indicating the location of the UE or an indication of the determined target satellite beam and the determined switching timing.

[0169] In some embodiments, the target satellite beam has a one-to-one correspondence with the serving cell, or the target satellite beam has a one-to-one correspondence with the synchronization signal block (SSB) index.

[0170] Further provided is a base station comprising a transceiver and circuitry, wherein the transceiver, during operation, transmits coverage area information indicating the coverage area of ​​at least one candidate satellite beam relative to the satellite position of at least one satellite that generates the at least one candidate satellite beam, and receives a location report indicating the position of a user equipment (UE) or a target satellite beam among the at least one candidate satellite beam and instruction information for a switching timing for the UE to switch to the target satellite beam, and the circuitry, during operation, determines the target satellite beam and the switching timing based on the received instruction information or based on the transmitted coverage area information, ephemeris data of the at least one satellite that generates the at least one candidate satellite beam, and the position of the UE indicated by the received location report, and terminates communication with the UE via the source serving beam at the determined switching timing.

[0171] In some embodiments, the transceiver, when operational, transmits coverage area information in system information.

[0172] In some embodiments, the transceiver transmits ephemeris data in system information during operation.

[0173] For example, the coverage area information includes, for each of at least one candidate satellite beam, a satellite beam direction and a radius or diameter of the coverage area, or a polygon that non-overlappingly defines the coverage area, or a center and radius of the coverage area.

[0174] For example, a target satellite beam has a one-to-one correspondence with a serving cell, or a target satellite beam has a one-to-one correspondence with a synchronization signal block (SSB) index.

[0175] Provided is a user equipment (UE) comprising a transceiver and a circuit, wherein the transceiver, in operation, transmits location information indicating a location of the UE and receives UE-specific signaling indicating at least one target satellite beam and at least one corresponding switch timing for switching to the at least one target satellite beam, and the circuit, in operation, controls the transceiver to perform switching to the at least one target satellite beam at the at least one corresponding switch timing indicated in the UE-specific signaling.

[0176] In some embodiments, the UE-specific signaling indicates multiple target satellite beams and multiple corresponding switching timings.

[0177] In some embodiments, the target satellite beam has a one-to-one correspondence with the serving cell, or the target satellite beam has a one-to-one correspondence with the synchronization signal block (SSB) index.

[0178] Further provided is a base station comprising a transceiver and a circuit, wherein the transceiver, in operation, receives location information indicating a location of a user equipment (UE) and transmits UE-specific signaling indicating at least one target satellite beam and at least one corresponding switch timing for the UE to switch to the at least one target satellite beam, and the circuit, in operation, determines at least one target satellite beam of the at least one candidate satellite beam and at least one corresponding switch timing based on coverage area information indicating a coverage area of ​​the at least one candidate satellite beam relative to a satellite position of at least one satellite that respectively generates the at least one candidate satellite beam, ephemeris data of the at least one satellite that generates the at least one candidate satellite beam, and the location of the user equipment indicated in a received position report.

[0179] For example, the coverage area information includes, for each of at least one candidate satellite beam, a satellite beam direction and a radius or diameter of the coverage area, or a polygon that non-overlappingly defines the coverage area, or a center and radius of the coverage area.

[0180] In some embodiments, the target satellite beam has a one-to-one correspondence with the serving cell, or the target satellite beam has a one-to-one correspondence with the synchronization signal block (SSB) index.

[0181] Further provided is a communication method including the following steps executed by a user equipment (UE): receiving coverage area information indicating a coverage area of ​​at least one candidate satellite beam relative to a satellite position of at least one satellite that generates the at least one candidate satellite beam, respectively; determining a target satellite beam to switch to from the at least one candidate satellite beam and a switching timing for switching to the target satellite beam based on the received coverage area information, ephemeris data of the at least one satellite that generates the at least one candidate satellite beam, and the position of the UE; and performing switching to the determined target satellite beam at the determined switching timing.

[0182] For example, the coverage area information is received in the system information.

[0183] In some embodiments, the ephemeris data is received in the system information.

[0184] In some embodiments, the ephemeris data is from a subscriber identity module (SIM) that stores the ephemeris data.

[0185] In some embodiments, the method includes transmitting a location report indicating the location of the UE or an indication of the determined target satellite beam and the determined switching timing.

[0186] In some embodiments, the target satellite beam has a one-to-one correspondence with the serving cell, or the target satellite beam has a one-to-one correspondence with the synchronization signal block (SSB) index.

[0187] Further provided is a communication method including the following steps executed by a base station: transmitting coverage area information indicating the coverage area of ​​at least one candidate satellite beam relative to the satellite position of at least one satellite that generates the at least one candidate satellite beam, respectively; receiving a position report indicating the position of a user equipment (UE) or a target satellite beam among the at least one candidate satellite beam and instruction information for switching timing for the UE to switch to the target satellite beam; determining a target satellite beam and switching timing based on the received instruction information or based on the transmitted coverage area information, ephemeris data of at least one satellite that generates the at least one candidate satellite beam, and the position of the UE indicated by the received position report; and terminating communication with the UE via the source serving beam at the determined switching timing.

[0188] In some embodiments, the coverage area information is transmitted in the system information.

[0189] In some embodiments, the ephemeris data is transmitted in the system information.

[0190] For example, the coverage area information includes, for each of at least one candidate satellite beam, a satellite beam direction and a radius or diameter of the coverage area, or a polygon that non-overlappingly defines the coverage area, or a center and radius of the coverage area.

[0191] For example, a target satellite beam has a one-to-one correspondence with a serving cell, or a target satellite beam has a one-to-one correspondence with a synchronization signal block (SSB) index.

[0192] A communication method is provided, the method including the following steps performed by a user equipment (UE): transmitting a location report indicating a location of the UE; receiving UE-specific signaling indicating at least one target satellite beam and at least one corresponding switch timing for switching to the at least one target satellite beam; and performing switching to the at least one target satellite beam at the at least one corresponding switch timing indicated in the UE-specific signaling.

[0193] In some embodiments, the UE-specific signaling indicates multiple target satellite beams and multiple corresponding switching timings.

[0194] In some embodiments, the target satellite beam has a one-to-one correspondence with the serving cell, or the target satellite beam has a one-to-one correspondence with the synchronization signal block (SSB) index.

[0195] Further provided is a communication method including the following steps executed by a base station: receiving a position report indicating a position of a user equipment (UE); determining at least one target satellite beam of the at least one candidate satellite beam and at least one corresponding switching timing for the UE to switch to the at least one target satellite beam based on coverage area information indicating a coverage area of ​​the at least one candidate satellite beam relative to a satellite position of at least one satellite that generates the at least one candidate satellite beam, respectively, ephemeris data of the at least one satellite that generates the at least one candidate satellite beam, and the position of the user equipment indicated in the received position report; and transmitting UE-specific signaling indicating the at least one target satellite beam and at least one corresponding switching timing for the UE to switch to the at least one target satellite beam.

[0196] For example, the coverage area information includes, for each of at least one candidate satellite beam, a satellite beam direction and a radius or diameter of the coverage area, or a polygon that non-overlappingly defines the coverage area, or a center and radius of the coverage area.

[0197] In some embodiments, the target satellite beam has a one-to-one correspondence with the serving cell, or the target satellite beam has a one-to-one correspondence with the synchronization signal block (SSB) index.

[0198] Further provided is an integrated circuit that, when operated, controls a user equipment (UE) for use in wireless communication to perform the following steps: receiving coverage area information indicating a coverage area of ​​at least one candidate satellite beam relative to a satellite position of at least one satellite that generates the at least one candidate satellite beam, respectively; determining a target satellite beam to switch to from the at least one candidate satellite beam and a switching timing for switching to the target satellite beam based on the received coverage area information, ephemeris data of the at least one satellite that generates the at least one candidate satellite beam, and the position of the UE; and performing switching to the determined target satellite beam at the determined switching timing.

[0199] For example, the coverage area information is received in the system information.

[0200] In some embodiments, the ephemeris data is received in the system information.

[0201] In some embodiments, the ephemeris data is from a subscriber identity module (SIM) that stores the ephemeris data.

[0202] In some embodiments, the integrated circuit controls the UE to transmit a location report indicating the location of the UE or to transmit an indication of the determined target satellite beam and the determined switching timing.

[0203] In some embodiments, the target satellite beam has a one-to-one correspondence with the serving cell, or the target satellite beam has a one-to-one correspondence with the synchronization signal block (SSB) index.

[0204] Further provided is an integrated circuit that, when operated, controls a base station for use in wireless communications to perform the following steps: transmitting coverage area information indicating the coverage area of ​​at least one candidate satellite beam relative to the satellite position of at least one satellite that generates the at least one candidate satellite beam, respectively; receiving a position report indicating the position of a user equipment (UE) or a target satellite beam among the at least one candidate satellite beam and instruction information for a switching timing for the UE to switch to the target satellite beam; determining a target satellite beam and a switching timing based on the received instruction information or based on the transmitted coverage area information, ephemeris data of at least one satellite that generates the at least one candidate satellite beam, and the position of the UE indicated by the received position report; and terminating communication with the UE via the source serving beam at the determined switching timing.

[0205] In some embodiments, the coverage area information is transmitted in the system information.

[0206] In some embodiments, the ephemeris data is transmitted in the system information.

[0207] For example, the coverage area information includes, for each of at least one candidate satellite beam, a satellite beam direction and a radius or diameter of the coverage area, or a polygon that non-overlappingly defines the coverage area, or a center and radius of the coverage area.

[0208] For example, a target satellite beam has a one-to-one correspondence with a serving cell, or a target satellite beam has a one-to-one correspondence with a synchronization signal block (SSB) index.

[0209] Further provided is an integrated circuit that, in operation, controls a user equipment (UE) for use in wireless communications to perform the following steps: transmitting a location report indicating a location of the UE; receiving UE-specific signaling indicating at least one target satellite beam and at least one corresponding switch timing for switching to the at least one target satellite beam; and performing a switch to the at least one target satellite beam at the at least one corresponding switch timing indicated in the UE-specific signaling.

[0210] In some embodiments, the UE-specific signaling indicates multiple target satellite beams and multiple corresponding switching timings.

[0211] In some embodiments, the target satellite beam has a one-to-one correspondence with the serving cell, or the target satellite beam has a one-to-one correspondence with the synchronization signal block (SSB) index.

[0212] Further provided is an integrated circuit that, when operated, controls a base station for use in wireless communications to perform the following steps: receiving a position report indicating a position of a user equipment (UE); determining at least one target satellite beam of the at least one candidate satellite beam and at least one corresponding switch timing for the UE to switch to the at least one target satellite beam based on coverage area information indicating a coverage area of ​​the at least one candidate satellite beam relative to a satellite position of at least one satellite that generates the at least one candidate satellite beam, ephemeris data of the at least one satellite that generates the at least one candidate satellite beam, and the position of the user equipment indicated in the received position report; and transmitting UE-specific signaling indicating the at least one target satellite beam and at least one corresponding switch timing for the UE to switch to the at least one target satellite beam.

[0213] For example, the coverage area information includes, for each of at least one candidate satellite beam, a satellite beam direction and a radius or diameter of the coverage area, or a polygon that non-overlappingly defines the coverage area, or a center and radius of the coverage area.

[0214] In some embodiments, the target satellite beam has a one-to-one correspondence with the serving cell, or the target satellite beam has a one-to-one correspondence with the synchronization signal block (SSB) index.

[0215] In summary, the techniques disclosed herein provide a user equipment (UE), a base station, and a method for the UE and the base station, the UE including a transceiver and a circuit, wherein the transceiver, during operation, receives coverage area information indicating coverage areas of at least one candidate satellite beam relative to satellite positions of at least one satellite that respectively generate the at least one candidate satellite beam, and the circuit, during operation, determines a target satellite beam to switch to among the at least one candidate satellite beam and a switching timing for switching to the target satellite beam based on the received coverage area information, ephemeris data of the at least one satellite that generates the at least one candidate satellite beam, and a position of the user equipment, and controls the transceiver to switch to the determined target satellite beam at the determined switching timing.

Claims

1. A communication device, a transceiver for receiving information indicating a reference point of a serving cell provided by at least one satellite beam and a distance from the reference point of the serving cell; a circuit for determining whether to switch from the at least one satellite beam to a target satellite beam based on a distance of the serving cell from a reference point and a distance between the communication device and the reference point; A communication device comprising:

2. the information is received in system information; The communication device according to claim 1 .

3. Ephemeris data is received in the system information. The communication device according to claim 2 .

4. The target satellite beam has a one-to-one correspondence with a serving cell, or the target satellite beam has a one-to-one correspondence with a synchronization signal block (SSB) index. The communication device according to claim 1 .

5. When the distance between the communication device and the reference point is shorter than the distance from the reference point of the serving cell, the at least one satellite beam that provided the information is selected. The communication device according to claim 1 .

6. 1. A communication method performed by a communication device, comprising: receiving information indicating a reference point of a serving cell provided by at least one candidate satellite beam and a distance from the reference point of the serving cell; determining whether to switch from the at least one satellite beam to a target satellite beam based on a distance of the serving cell from a reference point and a distance between the communication device and the reference point; A communication method including:

7. 1. An integrated circuit for controlling a communication device, comprising: a transceiver circuit for receiving information indicative of a reference point of a serving cell provided by at least one candidate satellite beam and a distance from the reference point of the serving cell; a control circuit that determines whether to switch from the at least one satellite beam to a target satellite beam based on a distance of the serving cell from a reference point and a distance between the communication device and the reference point; 1. An integrated circuit comprising:

Images