Communication device and communication method

Abstract

The techniques disclosed herein provide a user equipment (UE), a base station, and a method for the UE and the base station. The UE includes 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.

Description

Technical Field

[0001] The present disclosure relates to signal transmission and reception in a communication system. In particular, the present disclosure relates to methods and apparatuses for such transmission and reception.

Background Art

[0002] 3GPP (3rd Generation Partnership Project) (registered trademark) is formulating the technical specifications of the next-generation mobile phone technology, also known as the fifth generation (5G), including the "NR" (New Radio) radio access technology (RAT) that operates in the frequency band up to 100 GHz. NR follows the technologies represented by LTE (Long Term Evolution) and LTE Advanced (LTE-A).

[0003] In systems such as LTE, LTE-A, and NR, through further modifications and options, it is possible to promote the efficient operation of not only the communication system but also specific devices related to the system.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

Non-Patent Document 5

Non-Patent Document 6

Non-Patent Document 7

[0005] A non-limiting and exemplary embodiment facilitates efficient handover and beam switching in a non-terrestrial network. [Means for Solving the Problems]

[0006] In one embodiment, the technology disclosed herein is a user equipment that, during operation, includes a transceiver that receives coverage area information indicating a coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that transmits at least one candidate satellite beam respectively; and a circuit that, during operation, based on the received coverage area information, the ephemeris data of at least one satellite that transmits at least one candidate satellite beam, and the position of the user equipment, determines a target satellite beam for switching among at least one candidate satellite beam and a switching timing for switching to the target satellite beam, and controls the transceiver to perform the switching to the determined target satellite beam at the determined switching timing.

[0007] Note that a general or specific embodiment can be implemented as a system, method, integrated circuit, computer program, storage medium, or any optional combination thereof.

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

Brief Description of the Drawings

[0009] Hereinafter, exemplary embodiments will be described in more detail with reference to the accompanying drawings and figures.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

Figure 26

Figure 27

Modes for Carrying Out the Invention

[0010] <5G NR System Architecture and Protocol Stack> 3GPP is working on the next release of the 5th generation cellular technology (simply called 5G), which includes the development of a new radio access technology (NR) operating at frequencies up to 100 GHz. The first version of the 5G standard was completed at the end of 2017, enabling 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 gNB (gNodeB), where the gNB terminates the NG radio access user plane (SDAP / PDCP / RLC / MAC / PHY) protocol and the control plane (RRC: Radio Resource Control) protocol towards the UE. The gNBs are interconnected with each other via the Xn interface. Further, the gNB is connected to the NGC (Next Generation Core) via the next generation (NG) interface, and more specifically, is connected to the AMF (Access and Mobility Management Function) (e.g., a specific core entity that executes the AMF) via the NG-C interface and to the UPF (User Plane Function) (e.g., a specific core entity that executes the UPF) via 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, see Section 6.4 of Non-Patent Document 1) sublayer, an RLC (Radio Link Control, see Section 6.3 of Non-Patent Document 1) sublayer, and a MAC (Medium Access Control, see Section 6.2 of Non-Patent Document 1) sublayer, and these sublayers are terminated at the gNB on the network side. In addition to this, a new sublayer of the access stratum (AS) (SDAP: Service Data Adaptation Protocol) is introduced on top of PDCP (see, for example, Section 6.5 of Non-Patent Document 1). A control plane protocol stack is also defined in NR (see, for example, Section 4.4.2 of Non-Patent Document 1). An overview of the functions of Layer 2 is described in Section 6 of Non-Patent Document 1. The functions of the RDCP sublayer, the RLC sublayer, and the MAC sublayer are described in Sections 6.4, 6.3, and 6.2 of Non-Patent Document 1, respectively. 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, the multiplexing of logical channels and scheduling and scheduling-related functions (including the processing of various numerologies).

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

[0015] The use cases / deployment scenarios of NR include enhanced mobile broadband (eMBB), ultra-reliable and low-latency communication (URLLC), and massive machine type communication (mMTC), and these services have diverse requirements regarding data rate, latency, and coverage. For example, eMBB is expected to support peak data rates (downlink 20 Gbps, uplink 10 Gbps) and user-perceived data rates on the order of three times that provided by IMT-Advanced. In contrast, for URLLC, more stringent requirements are extremely low latency (user-plane latency is 0.5 ms for both uplink and downlink) and high reliability (1 to 10 within 1 ms) -5) is imposed. Furthermore, in mMTC, a high connection density (1,000,000 devices per km in an urban environment), wide coverage in harsh environments, and an extremely long - life battery (15 years) to reduce device cost may preferably be required. 2 For example, in a low - latency service, a shorter symbol duration (and thus a larger sub - carrier spacing) than the mMTC service, and / or fewer symbols per scheduling interval (also referred to as TTI) may preferably be required. Furthermore, in a deployment scenario with a large channel delay spread, a longer cyclic prefix (CP) duration may preferably be required than in a scenario with a short delay spread. To maintain the same level of cyclic prefix (CP) overhead, the sub - carrier spacing should be optimized according to the delay spread. In NR, more than two values of sub - carrier spacing can be supported. Therefore, currently, sub - carrier spacings of 15 kHz, 30 kHz, 60 kHz,... are being considered. The symbol duration T

[0016] Thus, an OFDM numerology (e.g., sub - carrier spacing, OFDM symbol duration, cyclic prefix (CP) duration, number of symbols per scheduling interval) suitable for one use - case may not function well in another use - case. For example, in a low - latency service, a shorter symbol duration (and thus a larger sub - carrier spacing) than the mMTC service, and / or fewer symbols per scheduling interval (also referred to as TTI) may preferably be required. Furthermore, in a deployment scenario with a large channel delay spread, a longer cyclic prefix (CP) duration may preferably be required than in a scenario with a short delay spread. To maintain the same level of cyclic prefix (CP) overhead, the sub - carrier spacing should be optimized according to the delay spread. In NR, more than two values of sub - carrier spacing can be supported. Therefore, currently, sub - carrier spacings of 15 kHz, 30 kHz, 60 kHz,... are being considered. The symbol duration T u and the sub - carrier spacing Δf are directly related by the formula Δf = 1 / T u Similar to the LTE system case, the term "resource element" can be used to represent the minimum resource unit composed of one sub - carrier with respect to 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 subcarriers 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] <Split of 5G NR functions between NG-RAN and 5GC> Figure 2 shows the split of functions 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 the time of 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 - Support for network slicing - QoS flow management and mapping to data radio bearers - Support for UEs in the RRC_INACTIVE state - Delivery function for NAS messages - Radio access network sharing - Dual connectivity - Tight interworking between NR and E-UTRA

[0020] The Access and Mobility Management Function (AMF) processes the following main functions. - Termination of non-access stratum (NAS) signaling - Security of NAS signaling - Security control of the access stratum (AS) - Core network (CN) node-to-node signaling for mobility between 3GPP access networks - Reachability of idle-mode UEs (including control and execution of paging retransmission) - Registration Area management - Support for intra-system mobility and inter-system mobility - Access authentication - Access authentication including roaming right check - Mobility management control (subscription and policy) - Support for network slicing - Selection of the Session Management Function (SMF) Furthermore, the User Plane Function (UPF) processes the following main functions.

[0021] - Anchor points for RAT-internal / RAT-inter RAT mobility (when applicable) - External PDU session point of interconnection with 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 reconfiguration 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 upper layer signaling (protocol) used for the configuration of the UE and gNB. In particular, in this transition, the AMF creates UE context data (including, for example, PDU session context, security keys, UE radio capabilities, UE security capabilities, etc.), and sends it to the gNB via the INITIAL CONTEXT SETUP REQUEST. Next, the gNB activates the AS security with the UE, which is executed by the gNB sending a SecurityModeCommand message to the UE and the UE responding to the gNB with a SecurityModeComplete message. Thereafter, the gNB executes the reconfiguration to establish the signaling radio bearer 2 (SRB2) and the data radio bearer (DRB), which is by the gNB sending an RRCReconfiguration message to the UE and the gNB receiving an RRCReconfigurationComplete from the UE in response. In the case of a signaling-only connection, since the SRB2 and DRB are not established, these steps related to RRCReconfiguration are skipped. Finally, the gNB notifies the AMF via the INITIAL CONTEXT SETUP RESPONSE that the establishment procedure is complete.

[0025] Therefore, in the present disclosure, an entity of the 5th Generation Core (5GC) (such as the AMF, SMF, etc.), comprising a control circuit that establishes a next-generation (NG) connection with the gNodeB during operation, and a transmitter that sends an initial context setup message to the gNodeB via the NG connection to establish a signaling radio bearer between the gNodeB and the user equipment (UE) during operation, is provided. Specifically, the gNodeB sends RRC (Radio Resource Control) signaling including a resource allocation configuration information element (IE) to the UE via the signaling radio bearer. The UE performs uplink transmission or downlink reception based on the resource allocation configuration.

[0026] <IMT Usage Scenarios Since 2020> Figure 4 shows some of the use cases of 5G NR. In the New Radio (3GPP NR) of the 3rd Generation Partnership Project (3GPP), three use cases are considered that are envisioned to support various services and applications according to IMT-2020. The specifications for Phase 1 of enhanced Mobile Broadband (eMBB) have been determined. As current and future work, in addition to further expanding the support for eMBB, the standardization of Ultra-Reliable and Low-Latency Communication (URLLC) and Massive Machine Type Communication is included. Figure 4 shows some examples of IMT usage scenarios envisioned since 2000 (see, for example, Figure 2 of Non-Patent Document 3).

[0027] The use case of URLLC has strict requirements regarding capabilities such as throughput, latency, and availability, and is envisioned as one of the means to realize 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. The ultra-reliability of URLLC is supported by identifying technologies to meet the requirements set by Non-Patent Document 4. In NR URLLC of Release 15, as an important requirement, a target user plane latency of 0.5 ms is included for both UL (uplink) and DL (downlink). The general URLLC requirement for a single packet transmission is a Block Error Rate (BLER) of 1E-5 with a packet size of 32 bytes at a user plane latency of 1 ms.

[0028] From a physical layer perspective, several methods for improving reliability can be considered. The current scope for improving reliability includes the definition of individual CQI tables for URLLC, more compact DCI (Downlink Control Information) formats, repetition of PDCCH, etc. However, as NR becomes more stable and development progresses (regarding the important requirements of NR URLLC), the scope for achieving ultra-high reliability can expand. Specific use cases of NR URLLC in Release 15 include extended reality / virtual reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0029] Furthermore, the technical enhancements targeted at NR URLLC aim to improve latency and reliability. Technical enhancements for improving latency include configurable numerology, non-slot-based scheduling using flexible mapping, grant-free 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 that is requested later and has a smaller latency / higher priority requirement. Therefore, an already permitted transmission is preempted by a later transmission. Preemption is applied regardless of the service type. For example, a transmission of service type A (URLLC) can be preempted by a transmission of service type B (such as eMBB). Technical enhancements related to improving reliability include dedicated CQI / MCS tables for a target BLER of 1E-5.

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

[0031] As described above, it is predicted that the range of reliability in NR will expand. One important requirement necessary in all cases, especially in the case of URLLC and mMTC, is high reliability or ultra-high reliability. From the wireless and network perspectives, several mechanisms for improving reliability can be considered. Generally, there are several important areas that may contribute to improving reliability. These areas include compact control channel information, repetition of data channels / control channels, diversity related to the frequency domain, time domain, and / or spatial domain. These areas are generally applicable to reliability regardless of the specific communication scenario.

[0032] In the case of NR URLLC, additional use cases with more stringent requirements have been identified, such as factory automation, transportation, and power distribution. The more stringent requirements, depending on the use case, include higher reliability (up to level 10), higher availability, a packet size of up to 256 bytes, time synchronization on the order of several μs (1 μs to several μs depending on the frequency range), a short latency on the order of 0.5 to 1 ms, especially a target user plane latency of 0.5 ms. -6 level), higher availability, a packet size of up to 256 bytes, time synchronization on the order of several μs (1 μs to several μs depending on the frequency range), a short latency on the order of 0.5 to 1 ms, especially a target user plane latency of 0.5 ms.

[0033] Furthermore, in the case of NR URLLC, several technical enhancements have been identified from the perspective of the physical layer. In particular, enhancements related to the PDCCH (Physical Downlink Control Channel) include compact DCI, repetition of the PDCCH, and increased PDCCH monitoring. Also, enhancements related to UCI (Uplink Control Information) include enhancements of HARQ (Hybrid Automatic Repeat reQuest) and CSI feedback. In addition, enhancements of the PUSCH related to hopping at the mini-slot level and enhancements of retransmission / repetition have also been recognized. The term "mini-slot" means a TTI (Transmission Time Interval) that contains a smaller number of 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. 1 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 (10 ms duration) composed of 10 subframes (1 ms duration). 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 a normal cyclic prefix and 12 for an 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 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). Therefore, at the NAS level, a QoS flow is the finest granularity of QoS differentiation in a PDU session. A QoS flow is identified within a PDU session by a QoS flow ID (QFI) that is carried in the encapsulation header through the NG - U interface.

[0036] The 5GC establishes one or more PDU sessions for each UE. The NG - RAN can establish, for each UE, at least one data radio bearer (DRB) together with a PDU session and then configure additional DRBs for the QoS flows of that PDU session as described above, for example with reference to Figure 3 (when to configure is determined by the NG - RAN). The NG - RAN maps packets belonging to different PDU sessions to different DRBs. UL and DL packets are associated with QoS flows by NAS - level packet filters in the UE and 5GC, and UL and DL QoS flows are associated with DRBs by AS - level mapping rules in the UE and NG - RAN.

[0037] Figure 5 shows the 5G NR non-roaming reference architecture (see Section 4.23 of Non-Patent Document 6). An Application Function (AF) (for example, an external application server that processes 5G services illustratively described in FIG. 4) interacts with the 3GPP core network for the purpose of providing services. For example, it supports the impact of an application on traffic routing, accesses the Network Exposure Function (NEF), and interacts with a policy framework (see Policy Control Function (PCF)) for policy control (e.g., QoS control). Based on the operator's deployment, an Application Function (AF) considered to be trusted by the operator can be made to directly interact with the relevant Network Function. An Application Function (AF) that is not permitted by the operator to directly access the network function uses an external exposure framework via the NEF to interact with the relevant network function.

[0038] Figure 5 shows further functional units of the 5G architecture, namely, the Network Slice Selection Function (NSSF), the Network Repository Function (NRF), the Unified Data Management (UDM), the Authentication Server Function (AUSF), the Access and Mobility Management Function (AMF), the Session Management Function (SMF), and the 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 deployed and executed in a cloud computing environment.

[0039] Therefore, in the present disclosure, there is provided an application server (e.g., AF in the 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 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, during operation, executes a service using the established PDU session.

[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 thereto, 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 forms, for example, 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 a wireless communication system including NR, a device or communication apparatus (e.g., UE) can be in different states according to traffic activities. In NR, a device can be in one of three RRC states, namely RRC_IDLE, RRC_CONNECTED, and RRC_INACTIVE. The first two RRC states, RRC_IDLE and RRC_CONNECTED, are the same as those in LTE, but RRC_INACTIVE is a new state introduced in NR and does not exist in the original LTE design. Also, depending on whether the device has established a connection with the core network, there are also core network states of CN_IDLE and CN_CONNECTED.

[0043] In RRC_IDLE, there is no RRC context (i.e., parameters necessary for communication between the device and the network) in the radio access network, and the device does not belong to a specific cell. From the perspective of the core network, the device is in the CN_IDLE state. Since the device is in a sleep state for most of the time to suppress battery consumption, data transfer is not performed. In the downlink, an idle state device wakes up periodically to receive paging messages from the network (if any). Mobility is handled by the device through cell reselection. Uplink synchronization is not maintained, and thus the only uplink transmission activity that can be performed is random access (e.g., for transitioning to the connected state). As part of the transition to the connected state, an RRC context is established in both the device and the network.

[0044] In the RRC_CONNECTED state, the RRC context is established, and all the parameters necessary for communication between the device and the radio access network are known to both entities. From the perspective of the core network, the device is in the CN_CONNECTED state. The cell to which the device belongs is known, and a C-RNTI (Cell Radio-Network Temporary Identifier), which is the identification information of the device used for signaling purposes between the device and the network, is set. The connected state aims at data transfer between the device, and discontinuous reception (DRX) can be set to reduce the power consumption of the device. Since the RRC context is established at the gNB in the connected state, ending DRX and starting data transmission and reception can be done relatively quickly because establishing a connection by related signaling is not required. Mobility is managed by the radio access network, that is, the device provides the network with measurement values of neighboring cells, and the network instructs the device to perform a handover if necessary. There may or may not be uplink time alignment, but random access is needed to establish and maintain it for data transmission.

[0045] In LTE, only the idle state and the connected state are supported. In fact, in order to reduce the power consumption of the device, it is common to use the idle state as the main sleep state. However, in many smartphone applications, it is common to frequently transmit small packets, and as a result, a large number of transitions from idle to active occur in the core network. These transitions are costly from the perspective of signaling load and related delays. Therefore, in NR, the RRC_INACTIVE state, which is the third state, is defined to reduce the signaling load and generally reduce the delay.

[0046] In RRC_INACTIVE, the RRC context is retained in both the device and the gNB. Also, the core network connection is maintained, i.e., the device is in the CN_CONNECTED state from the perspective of the core network. Therefore, the transition to the connected state for data transfer is fast. Core network signaling is not required. The RRC context already exists within the network, and the transition from idle to active can be processed within the radio access network. At the same time, the device can sleep in the same way as when it is in the idle state, and mobility is processed through cell reselection, i.e., without network involvement. Therefore, the mobility of the communication device or communication apparatus is device-controlled rather than network-controlled, and the communication device can contact the network through random access. Thus, RRC_INACTIVE can be regarded as a mixture of the idle state and the connected state (see Sections 6.5.1 to 6.5.3 of Non-Patent Document 7 for further details).

[0047] <Non-Terrestrial Network (NTN)> In 3GPP, NR-based operations in NTN (Non-Terrestrial Network) are being studied and described (see, for example, Non-Patent Document 8 and Non-Patent Document 9).

[0048] Space / airborne vehicles have a wide service coverage and low vulnerability to physical attacks and natural disasters. Therefore, NTN can facilitate the deployment of NR services in areas that cannot be covered by terrestrial NR networks (such as isolated areas or remote locations, inside aircraft or ships) and unserved areas (such as suburbs and rural areas). Furthermore, NTN can enhance the reliability of NR services by providing service continuity to passengers on moving platforms or ensuring service availability everywhere, especially for critical communications.

[0049] These advantages are associated with either a non-terrestrial network operating independently or a network integrating terrestrial and non-terrestrial components, and can affect coverage, user bandwidth, system capacity, and the reliability and availability of services.

[0050] A non-terrestrial network refers to, for example, a network using RF resources mounted on a satellite or a part of a network. NTN usually includes the following system elements: an NTN terminal (referring to a 3GPP UE or a terminal specific to a satellite system if the satellite does not directly provide services to the 3GPP UE), a service link meaning the radio link between a user device and a space / air platform, an air platform carrying a payload, a gateway connecting the space / air platform to a core network, and a feeder link meaning the radio link between the gateway and the space / air platform.

[0051] Figure 6 shows a scenario of a non-terrestrial network. The transmission between terminals (UEs) is carried out via a remote radio device including a satellite and an NTN gateway. A gNB is deployed as a scheduling device in the gateway. The satellite payload performs frequency conversion and radio frequency amplification in both the uplink and downlink directions. Therefore, the satellite repeats 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 scenario of a non-terrestrial network. The transmission between terminals (UEs) is executed via a satellite including a gNB as a scheduling device. A satellite with this configuration is called a regenerative relay satellite.

[0053] At NTN, various types of platforms are considered, such as artificial satellites and UAS (Unmanned Aerial System) platforms, and examples are shown in Table 1 (this table corresponds to Table 4.1-1 of Non-Patent Document 9, see also Section 4.1, "Non-Terrestrial Networks overview" of Non-Patent Document 9).

Table 1

[0054] Since LEO satellites, MEO satellites, and HEO satellites do not maintain a fixed position relative to a certain point on the Earth, the satellite beams corresponding to the cells or PCI (Physical Cell ID) or SSB (Synchronization Signal Block) beams of the NR radio system may move on the Earth.

[0055] Regarding the mapping between satellite beams, NR cells, and NR SSB beams, different deployment options, such as options a and b shown in FIGS. 8 and 9, can be considered. According to deployment option a shown in FIG. 8, one cell (corresponding to PCI) has multiple satellite beams (for example, the same PCI for multiple satellite beams), while according to deployment option b shown in FIG. 9, one cell corresponds to one satellite beam (there is one PCI for each satellite beam).

[0056] A satellite beam can be composed of one or more SSB beams. For example, one satellite beam can be mapped to one SSB beam, and for example, 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 an SSB beam. One NR cell (PCI) can have a maximum of L SSB beams, and L can be 4, 8, or 64 depending on the bandwidth. The SSB beam can be used as a reference beam for beam management in NR.

[0057] An NTN scenario that provides a cell that continuously moves on the Earth (for example, an LEO, MEO, or HEO-based NTN) is called an Earth-mobile cell scenario. The Earth-mobile cell scenario is shown in FIG. 10. The continuous movement of the cell on the Earth is due to the operation in which the satellite beam is fixed to the NTN platform. Therefore, according to the deployment options a and b described above, the footprints of some satellite beams or the cells corresponding to one satellite beam move on the Earth's surface along with the movement of the NTN platform (for example, the LEO satellite shown in FIG. 10).

[0058] Information about a satellite's orbit is included in ephemeris data (or "satellite ephemeris data"). There are various ways to represent ephemeris data, and one possible way is to use orbital parameters such as the semi-major axis, eccentricity, inclination angle, right ascension of the ascending node, argument of perigee, mean anomaly at a reference point in time, and epoch. The first five parameters can determine the orbital plane (orbital plane parameters), and the remaining two parameters are used to determine the exact satellite position at a certain 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 coordinates (x, y, z) of the satellite position, the velocity vector (vx, vy, vz), and the reference time point. [Table 2]

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

[0060] However, in a network with a large number of satellites, the size of the ephemeris data can become quite large. Therefore, instead of storing the ephemeris data, at least a part of the ephemeris data can be transmitted from the gNB.

[0061] For example, the satellite-level orbital parameters of all satellites that can provide services to the UE can be stored in the UE or the SIM, and the ephemeris data of each satellite is linked to the 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 SIM or storage device of the UE.

[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. The 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 the SIM, it is sufficient to broadcast the mean anomaly value at the reference time point, and the epoch needs to be broadcast to the UE, thus reducing the overhead.

[0063] Due to the high moving speed of the satellite relative to a fixed position on the earth, frequent SSB switching may occur in the case of deployment option a, or frequent handover (HO) may occur in the case of deployment option b. For example, in the reference scenario, the ground diameter of the NTN LEO cell is 50 km and the ground speed of the satellite is 7.56 km / s. In this case, a stationary UE needs to perform HO every 6.61 seconds.

[0064] In the NR terrestrial network, usually, the target cell and / or target SSB beam are selected based on measuring the reference signal (RS) from adjacent cells / beams and reporting the measurement value (e.g., reference signal received power (RSRP)) to the gNB. Then, the target cell or target SSB beam is indicated to the UE via, for example, 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 in the NTN mobile cell scenario, frequent measurement and reporting of the reference signal (RS) to indicate a cell or SSB beam may result in increased signaling overhead and UE power consumption. 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 a technique for determining a serving cell and a serving beam in a non-terrestrial network such as NR NTN. Based on information regarding the UE's position and the movement status of terrestrial cells / beams, 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 are determined.

[0067] A user equipment 1260 and a base station 1210 shown in FIG. 12 are provided. 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 is an NR user equipment, and the base station can be a network node or a 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 can also be applied to other wireless systems or cellular systems such as NTN.

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

[0069] As further shown in FIG. 12, the base station 1210 includes a transceiver 1220 (“base station transceiver”) and a circuit 1230 (“base station circuit”). For example, the base station circuit 1230 can include a satellite beam switching circuit 1235. The exemplary satellite beam switching circuit shown in FIG. 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, during operation, the UE transceiver 1270 receives coverage area information indicating the coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that each generates at least one candidate satellite beam.

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

[0072] The UE circuit 1280 · receives the received coverage area information, · ephemeris data of at least one satellite that generates at least one candidate satellite beam, · the position of the user equipment, and based on these, selects a target satellite beam for switching among at least one candidate satellite beam. For example, the UE circuit 1280 selects a target satellite beam from among the candidate satellite beams by performing calculations based on the coverage area information, the ephemeris data, and the position of the UE. Further, the UE circuit 1280 determines (e.g., derives or calculates) the switching timing for switching to the target satellite beam based on the coverage area information, the ephemeris data, and the position of the UE.

[0073] During operation, the UE circuit 1280 controls the UE transceiver 1270 to perform a switch to a determined or selected target satellite beam at a determined switching timing. Therefore, the UE switches to the determined target satellite beam at the determined switching timing.

[0074] Corresponding to the UE described above, a communication method executed by the UE is provided. As shown in FIG. 15, the communication method (abbreviated as "UE method") includes a step S1510 of receiving coverage area information indicating a coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that respectively generates at least one candidate satellite beam. For example, the coverage area information is received from a base station. The UE method includes a step S1520 of determining a target satellite beam for switching among at least one candidate satellite beam and a switching timing for switching to the target satellite beam. In this case, the determination of the target satellite beam and the determination of the switching timing are performed based on the received coverage area information, the ephemeris data of at least one satellite that generates at least one candidate satellite beam, and the position of the UE. The UE method further includes a step S1530 in which the UE performs a switch 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, UE 1260 communicates with 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 the satellite beam. When the UE switches to the target satellite beam, it starts communicating with the same base station (in the case of switching the serving beam where the target serving cell is the same cell as the source serving cell) or the target base station (in the case of handover) via the target satellite beam and communicates via the target satellite beam after the determined switching timing. The UE's communication via the target satellite beam, such as communication regarding how the switching timing is defined, can already start before the switching timing (e.g., by transmitting a RACH preamble) depending on the type of signaling and the definition of the switching timing. Generally, the source serving cell may be an NTN cell (e.g., the source serving beam is a satellite beam), or may be a cell of a terrestrial base station.

[0076] As described above and shown in FIGS. 8 and 9, a single serving cell (PCI) may correspond to multiple satellite beams (deployment option a in FIG. 8), or there may be a one-to-one correspondence between the serving cell and the satellite (option b in FIG. 9). In the present disclosure, switching of the satellite beam, or switching to the target beam, means 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 the UE method, by receiving coverage area information, the UE is provided with information regarding how a terrestrial cell or a beam area is defined (e.g., footprint coverage), which generally includes at least one of the size and shape of the cell and, in some cases, the position of the cell with respect to satellite coordinates derivable from ephemeris data. Further, the satellite ephemeris data provides information regarding how the terrestrial cell or beam is moving. Further, assuming that the UE knows its position, e.g., via GNSS (Global Navigation Satellite System), the UE knows which terrestrial cell or beam area covers its position at which timing. Thus, based on the information regarding how the terrestrial cell or beam is defined and how it is moving, and the knowledge of its own position, the UE determines the serving beam and possibly the serving cell as the target beam or target cell for handover.

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

[0079] In the case of an IDLE UE and an INACTIVE UE, the selection of the target serving cell and / or the target beam need not be recognized by the base station. However, in the case of a CONNECTED UE, the UE 1260 and the base station 1210 should have the same recognition. For example, when communication is performed via a physical uplink channel and / or a downlink control channel and / or a shared channel, such common recognition may be necessary for the base station to know the timing at which to stop communication with the UE. This common recognition 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 transmits a location report indicating the location of the UE during operation. Alternatively or in addition, the UE can directly report the switching timing and, in some cases, the target satellite beam (e.g., the selected cell or beam). Thus, the UE transceiver 1270 transmits indication information of the determined target satellite beam and the determined switching timing during operation. When the UE directly transmits the switching timing and, in some cases, the target satellite beam to the base station, the gNB can avoid the process for determining the switching timing and, in some cases, the target beam.

[0080] It should be further noted that the present disclosure is not limited to the UE receiving coverage area information. For example, the coverage area information may be stored in a memory of the UE such as a ROM (Read-only Memory) or 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 part of the coverage area information is stored in the UE or the SIM and the remaining part of the coverage information is received in the broadcast, similar to the discussion regarding the above satellite ephemeris data.

[0081] Furthermore, ephemeris data can be broadcast by system information such as SIB, or stored in the internal storage or SIM of the UE. For example, ephemeris data, or at least a part of the ephemeris data, can be received by the UE in SIB or, alternatively, in RRC signaling. As another example, the UE can include a SIM interface, and the SIM interface can receive ephemeris data or a stored part of the ephemeris data from the SIM storing the ephemeris data during operation. The ephemeris data can be broadcast in system information in addition to or without coverage area information (i.e., the coverage area information is stored in the UE / SIM). Also, the ephemeris data can include coverage area information.

[0082] As described above, satellite ephemeris data can be classified into orbital plane parameters and satellite level parameters. For example, although ephemeris data is broadcast to the UE via SIB, in order to reduce broadcast overhead, SIB can provide parameters related to a few adjacent satellites as satellites for generating candidate satellite beams.

[0083] During operation, the transceiver 1220 of the base station 1210 that communicates with the UE of the above-described embodiment transmits coverage area information indicating the coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that each generates at least one candidate satellite beam to, for example, the UE 1260. During operation, the transceiver 1220 of the base station further receives, for example, from the UE 1260, a position report indicating the position of the UE 1260, or instruction information on a target satellite beam among at least one candidate satellite beam and switching timing for the UE to switch to the target satellite beam.

[0084] During operation, the base station circuit 1230 determines the target satellite beam and the handover timing based on the received instruction information, or based on the transmitted coverage area information, the ephemeris data of at least one satellite that generates at least one candidate satellite beam, and the position of the UE indicated by the received position report.

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

[0086] In the case of handover, the base station terminates the communication with the UE via the source serving beam, and the UE starts communication with another base station (target base station) that provides services to the target cell via the target satellite beam. When switching beams within the same serving cell, the base station terminates the 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 this case, the base station terminates the communication with the UE by the handover timing, for example, before or at the handover timing, and stops the execution of downlink transmission and the reception of uplink transmission. Alternatively, for example, when the target satellite beam is the serving beam of the same cell, the base station switches the UE from the source serving beam where the current communication is being performed to the target serving beam. For example, the base station terminates the communication with the UE via the source beam (uplink transmission and downlink transmission) and starts communication with the UE via the target satellite beam.

[0088] Corresponding to the foregoing description of the base station, a communication method (abbreviated as "base station method") executed by the base station is provided, and FIG. 16 shows this method. This method includes a step S1610 of transmitting coverage area information indicating a coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that respectively generates at least one candidate satellite beam. Further, the base station method includes a step S1615 of receiving a position report indicating the position of a user equipment (UE), or instruction information of a target satellite beam among at least one candidate satellite beam and 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. This determination of the target satellite beam and the switching timing is performed based on the received instruction information, or based on the transmitted coverage area information, ephemeris data of at least one satellite that generates at least one candidate satellite beam, and the position of the UE indicated by the received position report. The base station method includes a step S1630 of ending communication with the UE via a source serving beam at the determined switching timing.

[0089] It should be understood that the embodiments and examples provided by the present disclosure refer to both the base station and the UE, as well as the device (e.g., the base station or the UE), and the method executed by the corresponding device. For example, the base station can transmit one or both of the coverage area information and the ephemeris data in system information or RRC signaling, unless otherwise specified or indicated by the context.

[0090] Furthermore, as already described, when the UE is in the CONNECTED mode, it is desirable to have a common understanding between the UE and the base station regarding the switching of satellite beams, for example, the switching of the target satellite beam and the switching timing.

[0091] However, in the case of IDLE UEs and INACTIVE UEs, the selection of a target satellite beam such as a serving cell or a serving beam does not need to be recognized by the base station. When communicating with a UE in the IDLE mode or the 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 the IDLE mode or the INACTIVE mode, steps S1615 to S1630 can be omitted. For this reason, in FIG. 14, the satellite beam switching time determination circuit 1436 and the satellite beam switching control circuit S1437 are shown by dashed lines.

[0092] In the above-described embodiment, a first method of the present disclosure is provided. In the first method, the UE determines a target satellite beam for switching and a timing of switching based on coverage area information, ephemeris data, and the position of the UE (all three pieces of information are available at the UE).

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

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

[0095] Correspondingly, during operation, the transceiver 1220 of the base station receives a position report indicating the position of the UE, and transmits UE-specific signaling indicating 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. In this case, the at least one target satellite beam, which is a satellite beam among the at least one candidate satellite beam, and the at least one corresponding switching timing are determined (e.g., calculated and / or selected) by the base station circuit 1230 based on the coverage area information indicating the coverage area of the at least one candidate satellite beam with respect to the satellite positions of the at least one satellite generating the at least one candidate satellite beam, the ephemeris data of the at least one satellite generating 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 method disclosed above, embodiments of a communication method for the UE ("UE method") and a communication method for the base station (base station method) are provided, and the steps of these methods are shown in FIGS. 17 and 18.

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

[0098] As can be further understood from FIG. 18, the base station method includes step S1815 of receiving a location report indicating the location of a user equipment (UE). The base station method further includes step S1820 of determining at least one target satellite beam among 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 the coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that respectively generates the at least one candidate satellite beam, ephemeris data of 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. Further, this method includes step S1825 of transmitting UE-specific signaling indicating 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.

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

[0100] As described, in the second approach, the UE is provided with UE-specific signaling indicating one or more target satellite beams and one or more switching timings. For example, after the UE reports its location (e.g., based on GNSS measurements), the UE is provided with a list of one or more serving cells and / or serving beams having associated execution timings (e.g., switching timings). Based on the indication 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 cells / beam areas are defined (e.g., coverage area information) and satellite ephemeris data (indicating the satellite and thus how 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 timing and can determine the target satellite beam for handover and the associated handover timing. For example, UE-specific RRC signaling can be used as UE-specific signaling regarding the target beam and handover timing.

[0102] For example, when a satellite beam and a serving cell have a one-to-one correspondence, the target satellite beam can be indicated by the cell ID (e.g., PCI) of the serving cell. Further, in the case of beam switching within a cell, the target satellite beam can be indicated, for example, by indicating the SSB (synchronization signal block) index.

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

[0104] In the second method, the base station can determine the plan for subsequent target cells / target beams by determining and providing a list of one or more target beams / target cells and their respective associated switching timings. For example, if there are switching timings for multiple target beams, the UE can perform multiple switches (handover or beam switching) without requiring new indication information for the next target beam or target cell for each handover or switching process.

[0105] In the following, several examples are provided regarding how a ground cell or beam area corresponding to the footprint coverage of a satellite beam on the Earth is defined, and these are shown in FIGS. 19 to 21. The following embodiments and examples can be combined with the first and second methods described above.

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

[0107] Next, the UE (first method) and / or the base station (e.g., second method) can select a satellite beam whose footprint covers the position of the UE.

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

[0109] In the second option shown in FIG. 20, the coverage area information includes polygons that define non-overlapping coverage areas. For example, each of the candidate satellite beams corresponds to a polygon or shape, and the polygons representing 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 different coverage areas. This information about the shape can be provided in addition to the PCI and / or SSB index corresponding to each candidate satellite beam. Then the UE (e.g., UE circuit 1280) can select the terrestrial area covering the UE's position as the target satellite beam, e.g., the serving cell or serving beam.

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

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

[0112] In a third option, as shown in FIG. 21, the coverage area information includes the center and radius of the coverage area. The UE (or UE circuit 1280) can select the satellite beam whose center is closest or nearest (e.g., has the smallest distance) to the position of the UE when the in-coverage distance, which can be the radius of the coverage area as shown in FIG. 21, is satisfied. Otherwise, if the in-coverage distance is not satisfied for any satellite beam or cell, the UE is out of coverage.

[0113] A third option that provides the center and radius of a coverage area, and a first option based on the direction of a satellite beam and the radius of the coverage area, are somewhat similar with respect to the parameters that are signaled. For example, since the beam center can be derived from the beam direction and the radius can be derived from the diameter, the same value pairs can be signaled in both options, or the radius can be provided in both options. Thus, the actual parameters signaled in the first option and the third option are interchangeable. However, as a difference between the first option and the third option, in the third option, the UE selects the satellite beam whose footprint center is closest to the position of the UE. Thus, the target satellite beam can be clearly determined without additional rules such as the ID-based rules described in relation to the first option. Further, for the purpose of controlling the distribution of users, 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 FIG. 21 will not be at the center (equal distance to the center points of both cells). Instead, the line can be shifted towards the beam center in a desired manner, for example, based on the bias value. The bias value can be selected, for example, based on the population density or UE density within the cell.

[0114] The above definition of the coverage area information according to the first to third options can be provided for the position of the satellite that changes over time and can be derived from ephemeris data for a given point in time, for example, the position of the satellite(s) generating the candidate satellite beam(s). As the satellite moves over time, the coverage area (e.g., size) can also change over time. For example, the size of the satellite beam area can be adjusted according to the density of UEs or population density in the area covered by the satellite beam. Therefore, when the satellite is moving over an area of the earth with a higher population density, the coverage area such as the beam footprint or the terrestrial cell / beam area can be reduced to provide smaller cells, thereby coping with the increased demand caused by more UEs that need to receive services.

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

[0116] Figure 22 shows a RACH-based handover from the source base station to the target base station. Step 2215a and step 2225b correspond to step S1715 and step S1725 of the UE method shown in FIG. 17, and step S2215b and step S2225a correspond to step S1815 and step S1825 of the base station method shown in FIG. 18. Further, in step S2220 corresponding to step S1820 of the base station method, the base station determines a plan for one or more subsequent target cells corresponding to the target satellite beam and the associated execution timing (e.g., handover timing) (these are transmitted to the UE by UE-specific RRC signaling).

[0117] After receiving the plan, until the UE executes a handover from the source base station to the target base station that provides services to the target cell via the target satellite beam, the UE can still continue the downlink and / or uplink traffic with the source base station (step S2226). In particular, in step S2228, the UE terminates the 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 the downlink communication with the source base station and switches to the target base station that provides services to the target cell. In the example shown in FIG. 22, the termination of the downlink communication with the source base station is performed at the signaling switching timing.

[0118] In the example of RACH-based handover shown in FIG. 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 the RACH preamble to the target base station before the indicated execution timing or switching timing and maintains the downlink reception from the source base station until the indicated switching timing.

[0119] FIG. 23 shows an example of RACH-less handover, that is, a handover that does not use RACH. The steps corresponding to the steps in FIG. 22 are indicated by the same reference numerals. In step S2329, the UE terminates the uplink transmission with the source base station and transmits an RRCReconfigurationComplete message to the target base station before the indicated timing.

[0120] FIG. 24 shows another example of signaling between a UE and a base station for handover, and the corresponding steps are labeled with the same reference numbers as in FIG. 23. As can be understood from FIG. 24, in step S2420 of determining the plan for the target cell, all the parameters necessary 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 of FIG. 23, the RRCReconfiguration signaling is not exchanged during handover.

[0121] FIG. 25 shows an example in step S2520 where the base station determines the plans for a plurality of target cells including the relevant execution (e.g., handover) timing, and the UE-specific RRC signaling indicates a plurality of target satellite beams and the corresponding handover timing. Similar to FIGS. 22 to 24 described above, this example includes steps 2215a, b and steps S2225a, b of transmitting / receiving UE location reports. However, in this example, the handover timing includes a first handover timing and a second handover timing. At the first handover timing, in step S2530a, the UE terminates the (UL and DL) communication with the source base station and switches to the first target base station. At the second handover timing, in step 2530b, the UE terminates the communication with the first target base station and switches to the second target cell served by the second target base station. Before the handover, the UE communicates with the source base station and the first target base station respectively (steps S2526a, b).

[0122] The example of FIG. 25 shows a handover without exchanging the RRCReconfiguration message. However, this case of signaling a plurality of target cells can be applied not only to RACH-based handover but also to RACH-less handover that exchanges the RRCReconfiguration message.

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

[0124] After the UE location report is transmitted / received (steps S2615a, b), when determining the target satellite beam and the target switching timing in step S2620, the base station determines the beam switching pattern for one or more CORESETs (Control Resource Sets). For example, the beam switching pattern indicates one or more satellite beams as the serving beam 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 PDCCH. Multiple CORESETs can be configured for the UE 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 which the UE monitors the PDCCH. Therefore, for different CORESETs, the beams can be different. Therefore, the beam switching patterns set for different CORESETs can also be different. If all CORESETs are always transmitted using the same beam, the same beam switching pattern can be set for all CORESETs.

[0126] Furthermore, for the purpose of achieving a trade-off between flexibility and signaling overhead, a beam switching pattern can be set for a subset of CORESETs configured for a UE. For a CORESET with a beam switching pattern, beam switching is performed at the relevant execution timing without additional signaling overhead. Such a scheme is expected to function well in a LOS (Line of Sight) scenario where the beam with the strongest signal strength is determined from location information. However, in a non-LOS scenario due to obstruction by, for example, buildings or mountains, simply determining the serving beam based on location information may not result in the strongest beam for the UE. To address such scenarios, some CORESETs are not set with a beam switching pattern. In that case, beam switching is dynamically indicated via a MAC CE (control element) as in Release 15 NR. Additionally, in a CORESET with a set beam switching pattern, a flag indicating the validity and invalidity of the set beam switching pattern can be used. When the beam switching pattern is valid, the UE switches to the beam indicated by the pattern at the relevant execution timing or switching timing. When the beam switching pattern is invalid, beam switching can follow the instruction 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. At the execution timing, the UE starts detecting the PDCCH and / or PDSCH using the new beam or target beam for the indicated CORESET (the CORESET configured with the beam switching pattern).

[0128] As shown in the example of FIG. 26, a beam switching pattern for the downlink channels (PDCCH, PDSCH) is provided. It may be set such that the same beam switching pattern or a different beam switching pattern is applied to the uplink transmissions of PUCCH and PUSCH. In the case of another uplink beam switching, for example, a pattern different from the downlink switching pattern, SRI (spatial relationship indication) may be used instead of TCI to represent the uplink beam switching pattern, and SRI can be provided in the PUCCH resource setting.

[0129] In FIGS. 22 to 25, the “execution timing” or “switching timing” is defined as the timing when the UE finishes 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 another definition of the switching timing at which another step or operation of switching from the source cell / source base station or the target cell / target base station is executed. For example, the switching timing may be the timing of transmitting a RACH preamble to the target cell (for example, in the case of a RACH-based handover), or the timing of transmitting an RRCReconfiguration message to the target cell (for example, in the case of a RACH-less handover).

[0130] Also, it is possible that the switching timing is defined differently between the UE and the gNB. For example, the switching timing of the UE is defined at the time of transmitting the RACH preamble, while the switching timing of the gNB is defined at the end of DL transmission.

[0131] Furthermore, for example, in the RACH-based handover shown in FIG. 22, the execution timing shown, or more generally, the handover 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 number of possible attempts for transmitting the RA preamble and monitoring the RA response. Therefore, the UE can transmit the preamble and, if the response is not received normally, perform one or more additional preamble transmissions until the maximum number of preambles is reached. If no RA response is received during that time window despite multiple attempts, the UE can declare a handover failure and initiate a cell reselection procedure as defined, for example, in NR Release 15 or Release 16.

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

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

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

[0135] Furthermore, the first method can be applied to beam switching. For example, a UE can select a beam switching pattern based on location, coverage area information, and ephemeris data, and indicate that beam switching pattern to the base station, optionally as a preferred beam switching pattern.

[0136] This disclosure describes switching to a target satellite beam. As described above, a target satellite beam can have a one-to-one correspondence with a serving cell, similar to each candidate satellite beam (e.g., the scenario of one satellite beam per cell shown in FIG. 9). Alternatively, in a scenario with multiple satellite beams per cell as shown in FIG. 8 for example, the target satellite beam can have a one-to-one correspondence with a Synchronization Signal Block (SSB) index.

[0137] According to this disclosure, the target satellite beam and the switching timing are determined based on the location of the UE (which can be a GNSS location). For example, as shown in FIG. 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, this disclosure is a communication device including a communication interface and a circuit. The communication interface receives, during operation, coverage area information indicating the coverage area of a candidate satellite beam with respect to the satellite position of the satellite generating the candidate satellite beam or the position of the UE to be switched. The circuit determines, during operation, based on the coverage area information, the ephemeris data of the satellite generating the candidate satellite beam, and the position of the UE to be switched, a candidate satellite beam that is the target satellite beam for switching, and a switching timing for switching to the target satellite beam.

[0139] Furthermore, the present disclosure provides a communication method executed by the communication device described in the previous paragraph, the communication method including: receiving coverage area information; and determining a target satellite beam and a switching timing for switching.

[0140] For example, according to the embodiments and aspects of the present disclosure, the communication device can be a user equipment (e.g., the first aspect) or a base station (e.g., the first aspect or the second aspect), and can be configured by the user equipment or the base station. When the communication device is a UE or is configured by a UE, the position of the UE is the position of the communication device. When the communication device is a base station or is configured by a base station, the position of the UE is received by a UE that reports the position of the UE.

[0141] The present disclosure facilitates the switching of satellite beams, including handover and serving beam switching. In particular, when the target satellite beam is determined based on coverage area information, ephemeris data, and the position of the UE, the need to frequently perform measurements and report measurement values can be alleviated. Further, when there is no need to perform measurements and reports, or when the frequency of measurements and reports is low, the power consumption of the UE can be reduced. Further, the need for the base station to select a target cell based on the received measurement report can be eliminated. Further, it is possible to minimize the interruption of communication during handover. For example, the exchange of handover requests from the source base station to the target base station and the confirmation response to the handover request can be omitted.

[0142] Furthermore, the embodiments related to the first aspect described above provide a mechanism for determining a target satellite beam and a mechanism for switching to the target satellite beam that can be applied particularly to a UE in any of the IDLE state, the INACTIVE state, and the CONNECTED state. Therefore, the method for determining the 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, in the second method, since the process of selecting a target satellite beam using the UE's position, coverage area information, and ephemeris data as inputs can be executed by the base station, it is possible to promote the reduction of the UE's processing load. Furthermore, since the UE does not need to receive coverage area information and / or ephemeris data for satellite beam switching, signaling overhead can be reduced.

[0144] In some implementation forms of NTN communication, either the first method or the second method of the present disclosure can be selected. However, it is also possible to combine both the first method and the second method.

[0145] One possibility is, for example, in a scenario where the satellite beam for a CONNECTED UE is different from the satellite beam for an IDLE UE and an INACTIVE UE, the IDLE UE and the INACTIVE UE use the first method, and the CONNECTED UE uses the second method.

[0146] Another possibility of combining the first method and the second method is to use the first method for inter-cell handover and the second method for beam management (which is also called "L1 (layer 1) mobility management"). Such a combination can be applied to one cell in relation to a plurality of beams, as shown in deployment option a (Figure 8).

[0147] Furthermore, in a scenario where the frequency reuse factor is greater than 1, information regarding the bandwidth portion used by each satellite beam can be included. When all cells or satellite beams use the same frequency or bandwidth, the frequency utilization rate is equal to 1, and when different cells such as adjacent cells use different portions of the bandwidth, the frequency reuse factor is greater than 1.

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

[0149] As described above, the measure of including bandwidth information and / or polarization information is possible in both the first method and the second method. 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 technology of the present disclosure can facilitate communication in NTN in, for example, a LOS (line of sight) scenario, but is also applicable to an NLOS (non-line of sight) scenario. The technology of the present disclosure can be combined with a measurement-based method for the purpose of facilitating a UE to maintain communication via the strongest available beam or a sufficiently strong beam (e.g., a beam having a maximum or at least sufficient signal strength and / or quality). Such a combination of a location-based method and a measurement-based method can be useful, for example, in an NLOS scenario when a beam that is sufficiently strong for the UE cannot necessarily be obtained simply by determining a serving cell or a serving beam based on location information, coverage information, and ephemeris information.

[0151] As an example of such a combination, the technology of the present disclosure for determining a target beam based on location data, coverage data, and ephemeris data is used to determine a target satellite beam and, in some cases, adjacent beams. After this selection, a measurement of the signal quality or signal strength of the selected target satellite beam can be performed. If the beam selected using the disclosed technology has sufficient quality, for example, if the RSRP (reference signal received power) or RSRQ (reference signal received quality) of the selected target satellite beam is greater than a threshold, measurements of the signal strength and / or signal quality targeting adjacent satellite beams or cells can be skipped or omitted.

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

[0153] Furthermore, the present disclosure is applicable to both the case of the transparent relay satellite shown in FIG. 6 and the case of the regenerative relay satellite shown in FIG. 7. Further, the disclosed technology can be applied to a communication system implementing both a terrestrial network and a non-terrestrial network, for example, handover from a base station having a ground-based antenna to an NTN base station having a transparent relay satellite and / or a regenerative relay satellite. For example, a target base station that generates a target satellite beam and, optionally, a serving base station such as a source base station may be located on the satellite.

[0154] Furthermore, although the present disclosure is directed to NTN communication, the disclosed technology can also be applied in a terrestrial network, for example, in a high-speed scenario, provided that in the case of the first method, the UE can derive or determine its own position or movement trajectory, or in the case of the second method, the base station can determine or predict the position or movement trajectory of the UE. For example, a target beam for switching, including a beam generated by a terrestrial antenna, can be determined based on the position or trajectory of the UE and the coverage area information of the (one or more) candidate beams.

[0155] The present disclosure can be implemented by software, by hardware, or by software cooperating with hardware. Each functional block used in the description of each of the above-described embodiments can be implemented in part or in whole by a large-scale integrated circuit (LSI) such as an integrated circuit (IC), and each process described in each embodiment can be controlled in part or in whole by the same LSI or a combination of LSIs. The LSI can be formed individually as a chip, or one chip can be formed so as to include part or all of the functional blocks. The LSI can include a data input / output section coupled to itself. Depending on the degree of integration, the LSI is also referred to as an IC, a system LSI, a super LSI, or an ultra LSI. However, the technology for implementing the integrated circuit is not limited to the LSI, and can be implemented by using an application-specific circuit, a general-purpose processor, or a dedicated processor. Furthermore, an FPGA (field programmable gate array) that can be programmed after the manufacture of the LSI, or a reconfigurable processor that can reconfigure the connection and setting of circuit cells arranged inside the LSI can also be used. The present disclosure can be implemented as digital processing or analog processing. As a result of the progress of semiconductor technology or another derivative technology, if the LSI is replaced by future integrated circuit technology, the functional blocks can be integrated using the future integrated circuit technology. Biotechnology can also be applied.

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

[0157] The communication device can include a transceiver and a processing / control circuit. The transceiver can include a receiver and a transmitter, and / or can function as a receiver and a transmitter. The transceiver as a transmitter and a receiver can 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 communication 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, smartwatches, tracking devices), game consoles, e-book readers, telemedicine / telehealth (remote medical / pharmaceutical) devices, vehicles providing communication functions (e.g., automobiles, airplanes, ships), and various combinations thereof.

[0159] The communication device is not limited to being portable or mobile, and can include any type of device, apparatus, or system that is non-portable or stationary, such as smart home devices (e.g., electrical appliances, lighting, smart meters, control panels), vending machines, and any other "things" within the network of the "Internet of Things (IoT)".

[0160] Communication can include, for example, the step of exchanging data through a cellular system, a wireless LAN system, a satellite system, among others, and various combinations thereof.

[0161] The communication device can include devices such as a controller or a sensor coupled to a communication device that executes the communication functions described in the present disclosure. For example, the communication device can include a controller or a sensor that generates a control signal or a data signal used by a communication device that executes the communication functions of the communication device.

[0162] The communication device can further include infrastructure facilities, such as base stations, access points, and any other devices, apparatuses, or systems that communicate with or control devices such as those in the non-limiting examples above.

[0163] A user equipment (UE) comprising a transceiver and a circuit, wherein the transceiver, during operation, receives coverage area information indicating a coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that generates the at least one candidate satellite beam, and the circuit, during operation, based on the received coverage area information, the ephemeris data of at least one satellite that generates the at least one candidate satellite beam, and the position of the user equipment, determines a target satellite beam for switching among the at least one candidate satellite beams and a switching timing for switching to the target satellite beam, and controls the transceiver to perform the switching 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, and this SIM interface receives ephemeris data from the SIM storing the ephemeris data during operation.

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

[0168] In some embodiments, the transceiver transmits, during operation, a position report indicating the position of the UE, or indication information 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 a serving cell, or the target satellite beam has a one-to-one correspondence with a Synchronization Signal Block (SSB) index.

[0170] Furthermore, there is provided a base station comprising a transceiver and a circuit, wherein the transceiver, during operation, transmits coverage area information indicating the coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that generates each of the at least one candidate satellite beam, receives a position report indicating the position of a User Equipment (UE), or an indication information of a target satellite beam among the at least one candidate satellite beam and a switching timing for the UE to switch to the target satellite beam, and the circuit, during operation, determines a target satellite beam and a switching timing based on the received indication information, or based on the transmitted coverage area information, the 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 terminates communication with the UE via a source serving beam at the determined switching timing.

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

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

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

[0174] For example, 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.

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

[0176] In some embodiments, the UE-specific signaling indicates a plurality of target satellite beams and a plurality of 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] Furthermore, there is provided a base station comprising a transceiver and a circuit, wherein the transceiver, during operation, receives position information indicating the position of a user equipment (UE), and transmits UE-specific signaling indicating 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, and the circuit, during operation, based on coverage area information indicating the coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that generates each of the at least one candidate satellite beams, ephemeris data of 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, determines at least one target satellite beam among the at least one candidate satellite beams and at least one corresponding switching timing.

[0179] For example, the coverage area information includes, for each of the at least one candidate satellite beam, the satellite beam direction and the radius or diameter of the coverage area, or a polygon defining the coverage area without overlap, or the center and radius of the coverage area.

[0180] In some embodiments, 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.

[0181] Furthermore, there is provided a communication method including the following steps executed by a user equipment (UE), namely, a step of receiving coverage area information indicating a coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that generates each of the at least one candidate satellite beams; a step of determining, based on the received coverage area information, ephemeris data of at least one satellite that generates the at least one candidate satellite beam, the position of the UE, a target satellite beam for switching among the at least one candidate satellite beams, and a switching timing for switching to the target satellite beam; and a step of executing a switch to the determined target satellite beam at the determined switching timing.

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

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

[0184] In some embodiments, the ephemeris data is from a subscriber identification module (SIM) storing the ephemeris data.

[0185] In some embodiments, the method includes a step of transmitting a position report indicating the position of the UE, or indication information 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 a serving cell, or the target satellite beam has a one-to-one correspondence with a synchronization signal block (SSB) index.

[0187] Furthermore, there is provided a communication method including the following steps executed by a base station, that is, a step of transmitting coverage area information indicating a coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that generates each of the at least one candidate satellite beams; a step of receiving a position report indicating the position of a user equipment (UE), or target satellite beam among the at least one candidate satellite beams and instruction information on switching timing for the UE to switch to the target satellite beam; a step of determining 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 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 a step of ending communication via a source serving beam with the UE at the determined switching timing.

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

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

[0190] For example, the coverage area information includes, for each of the at least one candidate satellite beam, a satellite beam direction and a radius or diameter of the coverage area, or a polygon that defines the coverage area without overlap, or a center and a radius of the coverage area.

[0191] For example, 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.

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

[0193] In some embodiments, the UE-specific signaling indicates a plurality of target satellite beams and a plurality of 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] Furthermore, a communication method, comprising the following steps performed by a base station: receiving a location report indicating the location of a user equipment (UE); determining at least one target satellite beam among 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 the coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that generates the at least one candidate satellite beam, ephemeris data of at least one satellite that generates the at least one candidate satellite beam, and the location of the user equipment indicated by the received location report; and transmitting UE-specific signaling indicating the at least one target satellite beam and the at least one corresponding switching timing for the UE to switch to the at least one target satellite beam, is provided.

[0196] For example, the coverage area information includes, for each of at least one candidate satellite beam, the satellite beam direction and the radius or diameter of the coverage area, or a polygon that defines the coverage area without overlap, or the 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] Furthermore, there is provided an integrated circuit that, during operation, controls a user equipment (UE) for use in wireless communication to perform the following steps: receiving coverage area information indicating the coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that generates each of the at least one candidate satellite beam; determining, based on the received coverage area information, the ephemeris data of at least one satellite that generates the at least one candidate satellite beam, the position of the UE, a target satellite beam for switching among the at least one candidate satellite beam, and a switching timing for switching to the target satellite beam; and performing a switch 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 perform the transmission of a location report indicating the location of the UE, or the transmission of indication information of a determined target satellite beam and a 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] Furthermore, there is provided an integrated circuit that, during operation, controls a base station for use in wireless communication to perform the following steps: transmitting coverage area information indicating the coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that generates each of the at least one candidate satellite beam; receiving a location report indicating the location of the user equipment (UE), or indication information of a target satellite beam among the at least one candidate satellite beam and 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 indication information, or based on the transmitted coverage area information, the 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; and ending communication with the UE via a 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, the satellite beam direction and the radius or diameter of the coverage area, or a polygon that defines the coverage area without overlap, or the center and radius of the coverage area.

[0208] For example, 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.

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

[0210] In some embodiments, the UE-specific signaling indicates a plurality of target satellite beams and a plurality of 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] Furthermore, there is provided an integrated circuit that, during operation, controls a base station for use in wireless communication to perform the following steps: receiving a location report indicating the location of a user equipment (UE); obtaining coverage area information indicating the coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that generates each of the at least one candidate satellite beams; obtaining ephemeris data of at least one satellite that generates the at least one candidate satellite beam; based on the location of the UE indicated by the received location report, the coverage area information, and the ephemeris data, determining at least one target satellite beam among the at least one candidate satellite beams and at least one corresponding switching timing for the UE to switch to the at least one target satellite beam; and transmitting UE-specific signaling indicating the at least one target satellite beam and the at least one corresponding switching 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 the at least one candidate satellite beam, the satellite beam direction and the radius or diameter of the coverage area, or a polygon defining the coverage area without overlap, or the center and radius of the coverage area.

[0214] In some embodiments, 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.

[0215] In summary, the technology disclosed in this specification provides a user equipment (UE), a base station, and methods for the UE and the base station. The UE includes a transceiver and circuitry. The transceiver, during operation, receives coverage area information indicating the coverage area of at least one candidate satellite beam with respect to the satellite positions of at least one satellite that generates at least one candidate satellite beam respectively. The circuitry, during operation, based on the received coverage area information, the ephemeris data of at least one satellite that generates at least one candidate satellite beam, and the position of the user equipment, determines a target satellite beam for switching among at least one candidate satellite beam and a switching timing for switching to the target satellite beam, and controls the transceiver to perform the switching to the determined target satellite beam at the determined switching timing.

Claims

1. A communication device, a transceiver that receives, during operation, coverage area information indicating a coverage area of at least one candidate satellite beam with respect to a satellite position of at least one satellite that generates the at least one candidate satellite beam, during operation, the received coverage area information, ephemeris data of the at least one satellite that generates the at least one candidate satellite beam, the position of the communication device, based on which, a target satellite beam for switching among the at least one candidate satellite beam is determined, and at a switching timing, a circuit that controls the transceiver to perform switching to the determined target satellite beam; A communication device comprising the above.

2. The coverage area information is received in system information. The communication device according to claim 1.

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

4. Further comprising a subscriber identification module (SIM) interface, and the SIM interface receives the ephemeris data from a SIM that stores the ephemeris data during operation. The communication device according to claim 1.

5. The coverage area information includes, for each of the at least one candidate satellite beam, a satellite beam direction and a radius or diameter of the coverage area, or a polygon that defines the coverage area so as not to overlap, or a center and a radius of the coverage area. Included. The communication device according to claim 1.

6. The transceiver transmits, during operation, a position report indicating the position of the communication device or instruction information on the determined target satellite beam and the switching timing. The communication device according to claim 1.

7. 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.

8. A communication method, comprising the following steps executed by a communication device, namely: Receiving coverage area information indicating a coverage area of at least one candidate satellite beam with respect to a satellite position of at least one satellite that generates the at least one candidate 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, The position of the communication device, Determining a target satellite beam for switching among the at least one candidate satellite beam; Executing a switch to the determined target satellite beam at a switching timing; A communication method including the above steps.

9. An integrated circuit for controlling a communication device, where the integrated circuit A transceiver circuit that receives, during operation, coverage area information indicating a coverage area of at least one candidate satellite beam with respect to a satellite position of at least one satellite that generates the at least one candidate satellite beam; During operation, Based on the received coverage area information, The ephemeris data of the at least one satellite that generates the at least one candidate satellite beam, and the position of the communication device, and Based on this, a target satellite beam for switching among the at least one candidate satellite beam is determined, and at the switching timing, a control circuit that controls the transceiver circuit to perform switching to the determined target satellite beam; An integrated circuit comprising.

Images