Terminal, network device, wireless communication system, and wireless communication method

Abstract

A terminal according to the present invention comprises a control unit and a transmission unit. When the terminal has been connected to a first network device, the control unit controls at least one of reestablishment with respect to a second network device and resumption with respect to the second network device, and the transmission unit uses identification information that identifies a terminal context for two or more network devices that include the first network device and the second network device to transmit at least one of a message that requests reestablishment with respect to the second network device and a message the requests resumption with respect to the second network device.

Description

Terminal, Network Device, Wireless Communication System, and Wireless Communication Method

[0001] The present disclosure relates to a terminal, a network device, a wireless communication system, and a wireless communication method that support communication of terminal context.

[0002] The 3rd Generation Partnership Project (3GPP: registered trademark) is standardizing the 5th generation mobile communication system (also called 5G, New Radio (NR), or Next Generation (NG)). Furthermore, 3GPP is also progressing with the standardization of the next generation, called Beyond 5G, 5G Evolution, or 6G.

[0003] In existing 3GPP specifications, in the case where RLF (Radio Link Failure) occurs at RAN node 1 and the terminal (UE; User Equipment) performs RRC Reestablishment for RAN node 2, or in the case where the UE transitions to the RRC inactive state at RAN node 1 and the UE performs RRC Resume for RAN node 2, RAN node 2 can obtain the UE context from RAN node 1 by transmitting the UE context ID (for example, Non-Patent Document 1).

[0004] 3GPP TS38.423 V18.3.0, September 2024

[0005] By the way, in existing 3GPP specifications, the UE context ID is composed of a PCI (Physical Cell ID) and a C-RNTI (Cell Radio Network Temporary Identifier), etc.

[0006] However, since it is conceivable that two or more cells under RAN node 1 may share the same PCI, in such cases, even if RAN node 2 sends the UE context ID to RAN node 1, RAN node 1 may not be able to uniquely identify the UE, potentially causing delays in operations such as RRC Reestablishment and RRC Resume.

[0007] Therefore, this disclosure has been made to solve the above-mentioned problems and aims to provide a terminal, network device, wireless communication system, and wireless communication method that can suppress delays associated with acquiring UE context.

[0008] The disclosed aspect is a terminal comprising: a control unit that controls at least one of re-establishing to a second network device or returning to the second network device when connected to a first network device; and a transmission unit that transmits at least one of a message requesting re-establishment to the second network device or a message requesting return to the second network device using identification information that identifies the terminal context in two or more network devices including the first network device and the second network device.

[0009] The disclosed aspect is a network device comprising a storage unit for storing a terminal context and a transmission unit for transmitting identification information that identifies the terminal context in two or more network devices.

[0010] The disclosed aspect is a network device comprising: a receiving unit that receives identification information for identifying a terminal context in two or more network devices; and a control unit that acquires the terminal context by transmitting the identification information to other network devices.

[0011] The disclosed aspect is a wireless communication system comprising a terminal, a first network device, and a second network device, wherein the terminal, when connected to the first network device, includes a control unit that controls at least one of re-establishing to the second network device or returning to the second network device, and a transmission unit that transmits at least one of a message requesting re-establishment to the second network device or a message requesting return to the second network device using identification information that identifies the terminal context in two or more network devices including the first network device and the second network device.

[0012] The disclosed aspect is a wireless communication method comprising: the step of controlling at least one of re-establishing to a second network device or returning to the second network device when connected to a first network device; and the step of transmitting at least one of a message requesting re-establishment to the second network device or a message requesting return to the second network device using identification information that identifies a terminal context in two or more network devices including the first network device and the second network device.

[0013] Figure 1 is an overall schematic diagram of the wireless communication system 10. Figure 2 is a diagram showing the frequency range used in the wireless communication system 10. Figure 3 is a diagram showing an example of the configuration of wireless frames, subframes, and slots used in the wireless communication system 10. Figure 4 is a functional block diagram of the UE200. Figure 5 is a functional block diagram of the gNB100. Figure 6 is a diagram for explaining the problem. Figure 7 is a diagram for explaining an example of operation. Figure 8 is a diagram for explaining an example of operation. Figure 9 is a diagram for explaining an example of operation. Figure 10 is a diagram for explaining example of operation 1. Figure 11 is a diagram for explaining example of operation 1. Figure 12 is a diagram for explaining example of operation 1. Figure 13 is a diagram for explaining example of operation 1. Figure 14 is a diagram for explaining example of operation 1. Figure 15 is a diagram for explaining example of operation 2. Figure 16 is a diagram for explaining example of operation 2. Figure 17 is a diagram for explaining example of operation 2. Figure 18 is a diagram for explaining example of operation 2. Figure 19 is a diagram for explaining example of operation 3. Figure 20 is a diagram illustrating Operation Example 3. Figure 21 is a diagram illustrating Operation Example 3. Figure 22 is a diagram illustrating Operation Example 3. Figure 23 is a diagram illustrating Operation Example 3. Figure 24 is a diagram illustrating Operation Example 3. Figure 25 is a diagram illustrating an example of the hardware configuration of the network device 50 and UE200. Figure 26 is a diagram illustrating an example of the configuration of the vehicle 2001.

[0014] The embodiments will be described below with reference to the drawings. Note that identical or similar reference numerals are used to denote the same functions and components, and their descriptions will be omitted as appropriate.

[0015] (1) Overall schematic diagram 1 of the wireless communication system is an overall schematic diagram of the wireless communication system 10 according to the embodiment. The wireless communication system 10 is a wireless communication system in accordance with 5G New Radio (NR) and includes a Next Generation-Radio Access Network 20 (hereinafter referred to as NG-RAN20) and a terminal 200 (hereinafter referred to as UE (User Equipment) 200).

[0016] The wireless communication system 10 may also be a wireless communication system that conforms to a method called Beyond 5G, 5G Evolution, or 6G.

[0017] NG-RAN20 includes base station 100 (hereinafter referred to as gNB100). The specific configuration of the wireless communication system 10, including the number of gNB100 and UE200, is not limited to the example shown in Figure 1.

[0018] NG-RAN20 actually includes multiple NG-RAN Nodes, specifically gNBs (or ng-eNBs), and is connected to a 5G-compliant core network (5GC, not shown). Note that NG-RAN20 and 5GC may also be simply referred to as the "network".

[0019] The gNB100 is a 5G-compliant radio base station that performs 5G-compliant wireless communication with the UE200. The gNB100 and UE200 can support Massive MIMO (Multiple-Input Multiple-Output), which generates a more directional beamband by controlling radio signals transmitted from multiple antenna elements; carrier aggregation (CA), which uses multiple component carriers (CCs) bundled together; and dual connectivity (DC), which enables simultaneous communication with two or more transport blocks between the UE and each of the two NG-RAN Nodes.

[0020] Furthermore, the wireless communication system 10 supports multiple frequency ranges (FR). Figure 2 shows the frequency ranges used in the wireless communication system 10.

[0021] Firstly, the wireless communication system 10 may support multiple frequency ranges (FRs) as shown in Figure 2. For example, the wireless communication system 10 may support FR1, FR2-1, and FR2-2. The frequency bands for each FR are as follows:

[0022] FR1: 410 MHz to 7.125 GHz FR2-1: 24.25 GHz to 52.6 GHz FR2-2: Over 52.6 GHz to 71 GHz In FR1, 15, 30, or 60 kHz Sub-Carrier Spacing (SCS) may be used, and a bandwidth (BW) of 5 to 100 MHz may be used. FR2 is a higher frequency than FR1, and 60 kHz or 120 kHz (240 kHz may be included) SCS may be used, and a bandwidth (BW) of 50 to 400 MHz may be used.

[0023] Note that SCS may also be interpreted as numerology. Numerology is defined in 3GPP TS38.300 and corresponds to a single subcarrier interval in the frequency domain.

[0024] Furthermore, the wireless communication system 10 may also support higher frequency bands than the FR2 frequency band. Specifically, the wireless communication system 10 may support frequency bands exceeding 52.6 GHz up to 71 GHz or 114.25 GHz.

[0025] Secondly, the wireless communication system 10 may correspond to the wireless frames, subframes, and slots shown in Figure 3.

[0026] As shown in Figure 3, one slot consists of 14 symbols, and the larger (wider) the SCS, the shorter the symbol duration (and slot duration). In addition to 15kHz, 30kHz, 60kHz, 120kHz, and 240kHz, 480kHz, 960kHz, etc., may also be used for the SCS.

[0027] Furthermore, the number of symbols constituting one slot does not necessarily have to be 14 (for example, 28 symbols, 56 symbols). In addition, the number of slots per subframe may differ depending on the SCS.

[0028] The time direction (t) shown in Figure 3 may also be called the time domain, symbol period, or symbol time. The frequency direction may also be called the frequency domain, resource block, subcarrier, or bandwidth part (BWP).

[0029] (2) Functional Block Configuration of the Wireless Communication System Next, the functional block configuration of the wireless communication system 10 will be described.

[0030] First, we will describe the functional block configuration of the UE200.

[0031] Figure 4 is a functional block diagram of the UE200. As shown in Figure 4, the UE200 comprises a wireless signal transmission / reception unit 210, an amplifier unit 220, a modulation / demodulation unit 230, a control signal / reference signal processing unit 240, an encoding / decoding unit 250, a data transmission / reception unit 260, and a control unit 270.

[0032] The wireless signal transceiver 210 transmits and receives wireless signals in accordance with NR. The wireless signal transceiver 210 supports Massive MIMO, CA which uses multiple CCs bundled together, and DC which communicates simultaneously between the UE and each of the two NG-RAN Nodes.

[0033] The amplifier section 220 consists of components such as a PA (Power Amplifier) ​​and an LNA (Low Noise Amplifier). The amplifier section 220 amplifies the signal output from the modulation / demodulation section 230 to a predetermined power level. The amplifier section 220 also amplifies the RF signal output from the wireless signal transmission / reception section 210.

[0034] The modulation / demodulation unit 230 performs data modulation / demodulation, transmit power setting, and resource block allocation for each predetermined communication destination (gNB100 or other gNB). The modulation / demodulation unit 230 may apply Cyclic Prefix-Orthogonal Frequency Division Multiplexing (CP-OFDM) / Discrete Fourier Transform - Spread (DFT-S-OFDM). Furthermore, DFT-S-OFDM may be used not only for the uplink (UL) but also for the downlink (DL).

[0035] The control signal / reference signal processing unit 240 performs processing related to various control signals transmitted and received by the UE200, and processing related to various reference signals transmitted and received by the UE200.

[0036] Specifically, the control signal / reference signal processing unit 240 receives various control signals transmitted from the gNB100 via a predetermined control channel, such as control signals for the radio resource control layer (RRC). The control signal / reference signal processing unit 240 also transmits various control signals to the gNB100 via a predetermined control channel.

[0037] The control signal / reference signal processing unit 240 performs processing using reference signals (RS) such as the Demodulation Reference Signal (DMRS) and the Phase Tracking Reference Signal (PTRS).

[0038] DMRS is a terminal-specific, known reference signal (pilot signal) between the base station and the terminal used to estimate the fading channel used for data demodulation. PTRS is a terminal-specific reference signal intended to estimate phase noise, which is a problem in the high-frequency band.

[0039] In addition to DMRS and PTRS, the reference signals may also include Channel State Information-Reference Signal (CSI-RS), Sounding Reference Signal (SRS), and Positioning Reference Signal (PRS) for location information.

[0040] Furthermore, channels include control channels and data channels. Control channels include PDCCH (Physical Downlink Control Channel), PUCCH (Physical Uplink Control Channel), RACH (Random Access Channel), Downlink Control Information (DCI) including Random Access Radio Network Temporary Identifier (RA-RNTI), and Physical Broadcast Channel (PBCH), among others.

[0041] Furthermore, data channels include PDSCH (Physical Downlink Shared Channel) and PUSCH (Physical Uplink Shared Channel), among others. "Data" refers to data transmitted through a data channel. A data channel may also be interpreted as a shared channel.

[0042] Here, the control signal / reference signal processing unit 240 may receive downlink control information (DCI). The DCI includes fields that store existing fields such as DCI Formats, Carrier indicator (CI), BWP indicator, FDRA (Frequency Domain Resource Assignment), TDRA (Time Domain Resource Assignment), MCS (Modulation and Coding Scheme), HPN (HARQ Process Number), NDI (New Data Indicator), and RV (Redundancy Version).

[0043] The value stored in the DCI Format field is an information element that specifies the format of the DCI. The value stored in the CI field is an information element that specifies the CC to which the DCI is applied. The value stored in the BWP indicator field is an information element that specifies the BWP to which the DCI is applied. The BWP that can be specified by the BWP indicator is set by an information element (BandwidthPart-Config) included in the RRC message. The value stored in the FDRA field is an information element that specifies the frequency domain resource to which the DCI is applied. The frequency domain resource is identified by the value stored in the FDRA field and an information element (RA Type) included in the RRC message. The value stored in the TDRA field is an information element that specifies the time domain resource to which the DCI is applied. The time domain resource is identified by the value stored in the TDRA field and an information element (pdsch-TimeDomainAllocationList, pusch-TimeDomainAllocationList) included in the RRC message. The time domain resource may be identified by the value stored in the TDRA field and a default table. The value stored in the MCS field is an information element that specifies the MCS to which the DCI is applied. The MCS is identified by the value stored in the MCS and an MCS table. The MCS table may be specified by the RRC message or may be identified by RNTI scrambling. The value stored in the HPN field is an information element that specifies the HARQ Process to which the DCI is applied. The value stored in the NDI is an information element for identifying whether the data to which the DCI is applied is initial transmission data. The value stored in the RV field is an information element that specifies the redundancy of the data to which the DCI is applied.

[0044] For each predetermined communication destination (gNB100 or another gNB), the encoding / decoding unit 250 performs data segmentation / concatenation, channel coding / decoding, and the like.

[0045] Specifically, the encoding / decoding unit 250 divides the data output from the data transmission / reception unit 260 into predetermined sizes and performs channel coding on the divided data. The encoding / decoding unit 250 also decodes the data output from the modulation / demodulation unit 230 and concatenates the decoded data.

[0046] The data transmission / reception unit 260 performs the transmission and reception of Protocol Data Units (PDUs) and Service Data Units (SDUs). Specifically, the data transmission / reception unit 260 performs assembly / decomposition of PDUs / SDUs at multiple layers (such as the Media Access Control Layer (MAC), Radio Link Control Layer (RLC), and Packet Data Convergence Protocol Layer (PDCP)). In addition, the data transmission / reception unit 260 performs error correction and retransmission control of data based on HARQ (Hybrid Automatic Repeat Request).

[0047] The control unit 270 controls each functional block that constitutes the UE200. In this embodiment, the control unit 270 may be configured to control at least one of the following when connected to the first network device (hereinafter referred to as RAN node 1): re-establishment to the second network device (hereinafter referred to as RAN node 2) or return to the second network device (hereinafter referred to as RRC Resume). In this embodiment, the wireless signal transmitting / receiving unit 210 described above may be configured to be a transmitting unit that uses identification information to identify the terminal context (hereinafter referred to as UE context) in two or more network devices, including the first network device (RAN node 1) and the second network device (RAN node 2), to transmit at least one of the following messages: a message requesting re-establishment to the second network device (RAN node 2) or a message requesting return to the second network device (RRC Resume).

[0048] Second, the functional block configuration of the network device 50 will be described. The network device 50 may be an example of a RAN node. The network device 50 may be the gNB 100 or a higher-level node. The higher-level node may be an OAM (Operation Administration and Maintenance) server. The network device 50 may be the MN (Master node) in dual connectivity or the SN (Secondary node) in dual connectivity. When the gNB 100 has a split configuration, the network device 50 may be the DU (Distributed Unit) or the CU (Central Unit).

[0049] FIG. 5 is a functional block configuration diagram of the network device 50. As shown in FIG. 5, the gNB 100 includes a receiving unit 51, a transmitting unit 52, a storage unit 53, and a control unit 54.

[0050] The receiving unit 51 may receive various signals from the UE 200. The receiving unit 51 may receive UL signals via PUCCH or PUSCH. The receiving unit 51 may receive various signals from other network devices.

[0051] The transmitting unit 52 may transmit various signals to the UE 200. The transmitting unit 52 may transmit DL signals via PDCCH or PDSCH. The transmitting unit 52 may transmit various signals to other network devices.

[0052] The storage unit 53 may store various information.

[0053] The control unit 54 may control each component of the network device 50.

[0054] In this embodiment, a Radio Link Failure (RLF) may occur at RAN node 1 (which may be read as Old RAN node), and UE200 may perform RRC Reestablishment to RAN node 2 (which may be read as New RAN node). A case may be assumed where UE200 transitions to an RRC inactive state at RAN node 1 (which may be read as Old RAN node), and UE200 performs RRC Resume to RAN node 2 (which may be read as New RAN node). A Handover from RAN node 1 (which may be read as Source RAN node) to RAN node 2 (which may be read as Target RAN node) may be assumed. Dual connectivity using RAN node 1 (which may be read as MN) and RAN node 2 (which may be read as SN) may be assumed. A Split configuration using RAN node 1 (which may be read as CU) and RAN node 2 (which may be read as DU) may be assumed.

[0055] In this embodiment, when the network device 50 is RAN node 1 (e.g., Old RAN node, Source RAN node, MN, CU) or a higher-level node, the storage unit 53 may be configured as a storage unit that stores terminal contexts (UE contexts), and the transmission unit 52 may be configured as a transmission unit that transmits identification information that identifies terminal contexts (UE contexts) in two or more network devices.

[0056] In this embodiment, when the network device 50 is RAN node 2 (e.g., New RAN node, Target RAN node, SN, DU), the receiving unit 51 may be configured to receive identification information that identifies the terminal context (UE context) in two or more network devices, and the control unit 54 may be configured to acquire the terminal context by transmitting the identification information to other network devices.

[0057] (3) Issues In the existing 3GPP specifications, in RRC Reestablishment, RRC inactive state, etc., RAN node 2 can obtain the UE context from RAN node 1 by sending the UE context ID (UE context retrieve). In the existing 3GPP specifications, the UE context ID is composed of PCI (Physical Cell ID) and C-RNTI (Cell Radio Network Temporary Identifier), etc.

[0058] However, since it is conceivable that two or more cells under RAN node 1 may share the same PCI, in such cases, even if RAN node 2 sends the UE context ID to RAN node 1, RAN node 1 may not be able to uniquely identify the UE, potentially causing delays in RRC Reestablishment and RRC Resume.

[0059] For example, consider the case shown in Figure 6, where Cell 1-1, Cell 1-2, and Cell 1-3 exist under RAN node 1, Cell 2 exists under RAN node 2, and Cell 3 exists under RAN node 3.

[0060] In such cases, when UE200 performs an RRC Reestablishment or RRC Resume on RAN node 2, RAN node 2 sends the UE context ID (including PCI, etc.) to RAN node 1, RAN node 1 identifies the UE context based on the UE context ID, and RAN node 1 sends the identified UE context to RAN node 2.

[0061] However, if UE200 is present in Cell 1-1, and the PCIs of Cell 1-1 and Cell 1-3 are the same, RAN node 1 cannot uniquely identify the UE context based on the UE context ID, which includes the PCI.

[0062] (4) Example of Operation In order to solve the above-mentioned problems, the following example of operation may be defined. Specifically, in the example of operation, a new concept called identification information is introduced to identify the terminal context (UE context) in two or more RAN nodes, as shown in Figure 7. Two or more RAN nodes may be called a RAN node set. A RAN node set may be read as a RAN node group. The identification information may be called a Unique UE context ID from the standpoint of distinguishing it from existing UE context IDs.

[0063] The higher-level node (e.g., OAM) can be any node that manages a RAN node set (or RAN node group). The higher-level node may also manage UE contexts in association with unique UE context IDs.

[0064] With this configuration, it is possible to uniquely identify the UE context between two or more RAN nodes by using a Unique UE context ID.

[0065] Here, as shown in Figure 8, the following options are possible for the Unique UE context ID.

[0066] In Option 1, the Unique UE context ID may include the RAN node set ID, RAN node ID, and UE context ID. The RAN node set ID is identification information that identifies a RAN node set, and the RAN node ID is identification information that identifies a RAN node. The RAN node set ID may also be interpreted as the RAN node group ID. The UE context ID is identification information that uniquely identifies a UE context within a RAN node set. The UE context ID may be called a New UE context ID to distinguish it from existing UE context IDs.

[0067] In Option 2, the Unique UE context ID may include the RAN node set ID, RAN node ID, Cell ID, and C-RNTI (or I(Inactive)-RNTI). The RAN node set ID is an identifier that identifies a RAN node set, and the RAN node ID is an identifier that identifies a RAN node. The RAN node set ID may be interpreted as the RAN node group ID. The Cell ID, unlike PCI, is an identifier that uniquely identifies a Cell in a RAN node set. For example, the Cell ID is the CGI (Cell Global ID). The C-RNTI (or I-RNTI) is information that uniquely identifies a UE in a Cell.

[0068] For example, as shown in Figure 9, a unique UE context ID may be newly defined as the UE context ID used in RRC Reestablishment or RRC Resume.

[0069] In the example, the upper-level node may issue a RAN node set ID and notify the RAN node of the RAN node set ID. The upper-level node may also manage the RAN node set ID in association with the Unique UE context ID.

[0070] (4.1) Operation Example 1 Operation Example 1 describes the operation of sending and receiving information about the Unique UE context ID between RAN nodes. The following options are possible for Operation Example 1.

[0071] Option 1-1 describes the sending and receiving of RAN node set IDs. The following options are possible for Option 1-1.

[0072] Option 1-1-1 describes the Xn setup procedure. As shown in Figure 10, in step S10, RAN node 1 sends an Xn setup request to RAN node 2. In step S11, RAN node 2 sends an Xn setup response to RAN node 1. The Xn setup request may include the RAN node set ID. The Xn setup response may also include the RAN node set ID.

[0073] Option 1-1-2 describes the RAN node configuration update procedure. As shown in Figure 11, in step S20, RAN node 1 sends an Xn configuration update to RAN node 2. In step S21, RAN node 2 sends an Xn configuration update Ack to RAN node 1. The Xn configuration update may include the RAN node set ID. The Xn configuration update Ack may also include the RAN node set ID.

[0074] Option 1-1-3 describes the case in which a higher-level node is involved. As shown in Figure 12, in step S30, the higher-level node sends the RAN node set ID to the RAN node. The RAN node may be a RAN node included in the RAN node set identified by the RAN node set ID.

[0075] According to option 1-1, the RAN node can properly obtain the RAN node set ID. By obtaining the RAN node set ID, the RAN node can identify the Unique UE context ID.

[0076] For example, in Option 1 shown in Figure 8, the RAN node can identify the Unique UE context ID by obtaining the RAN node ID and New UE context ID in addition to the RAN node set ID.

[0077] For example, in Option 2 shown in Figure 8, the RAN node can identify the Unique UE context ID by obtaining the RAN node ID, Cell ID, and C-RNTI (or I-RNTI) in addition to the RAN node set ID.

[0078] According to option 1-1, a RAN node can determine whether other RAN nodes belong to the same RAN node set by exchanging RAN node set IDs.

[0079] Option 1-2 describes sending and receiving Unique UE context IDs. The following options are possible for Option 1-2.

[0080] Option 1-2-1 describes the operation between RAN nodes. As shown in Figure 13, in step S40, RAN node 1 determines the Unique UE context ID. In Option 1 shown in Figure 8, it can also be considered that RAN node 1 determines the New UE context ID. In step S41, RAN node 1 sends the Unique UE context ID to RAN node 2. In Option 1 shown in Figure 8, RAN node 1 may also send the New UE context ID to RAN node 2.

[0081] Thus, the Unique UE context ID may be issued by RAN node 1.

[0082] Option 1-2-2 describes the operation between the RAN node and the higher-level node. As shown in Figure 14, in step S50, the higher-level node sends a Unique UE context ID to the RAN node. In Option 1 shown in Figure 8, the higher-level node may also send a New UE context ID to the RAN node. The RAN node may be a RAN node included in the RAN node set identified by the RAN node set ID.

[0083] Thus, the Unique UE context ID may be issued by the parent node.

[0084] According to option 1-2, the RAN node can properly obtain the Unique UE context ID.

[0085] (4.2) Operation Example 2 Operation Example 2 describes the operations related to RRC Reestablishment and RRC Resume. Operation Example 2 may also be an operation example that assumes the Unique UE context ID described in Operation Example 1. The following options are possible for Operation Example 2.

[0086] Option 2-1 describes RRC Reestablishment. The following options are possible for Option 2-1.

[0087] Option 2-1-1 primarily describes the operation between RAN nodes. As shown in Figure 15, an RLF occurs between the Old RAN node and the UE in step S60. In step S61, the UE sends an RRCReestablishmentRequest to the New RAN node using the Unique UE context ID. In step S62, the New RAN node sends a Retrieve UE context request to the Old RAN node using the Unique UE context ID. In step S63, the Old RAN node identifies the UE context based on the Unique UE context ID and sends a Retrieve UE context response containing the identified UE context to the New RAN node. In step S64, the New RAN node sends an RRCReestablishment to the UE.

[0088] In option 2-1-1, "using a Unique UE context ID" may be interpreted as "including a Unique UE context ID."

[0089] In option 2-1-1, since the RRCReestablishmentRequest is sent by an unsecured SRB (Signaling Radio Bearer) 0, the Unique UE context ID included in the RRCReestablishmentRequest may be a Short unique UE context ID. A Short unique UE context ID may be composed of a portion of the bit sequence that makes up the Unique UE context ID.

[0090] Option 2-1-2 primarily describes the operation between the RAN node and the upstream node. As shown in Figure 16, an RLF occurs between the Old RAN node and the UE in step S70. In step S71, the UE sends an RRCReestablishmentRequest to the New RAN node using the Unique UE context ID. In step S72, the New RAN node sends a Retrieve UE context request to the upstream node using the Unique UE context ID. In step S73, the upstream node identifies the UE context based on the Unique UE context ID and sends a Retrieve UE context response containing the identified UE context to the New RAN node. In step S74, the New RAN node sends an RRCReestablishment to the UE.

[0091] In option 2-1-2, "using a Unique UE context ID" may be interpreted as "including a Unique UE context ID."

[0092] In option 2-1-2, since the RRCReestablishmentRequest is sent by an unsecured SRB (Signaling Radio Bearer) 0, the Unique UE context ID included in the RRCReestablishmentRequest may be a Short unique UE context ID. A Short unique UE context ID may be composed of a portion of the bit sequence that makes up the Unique UE context ID.

[0093] Option 2-2 will explain RRC Resume. The following options are possible for Option 2-2.

[0094] Option 2-2-1 primarily describes the operation between RAN nodes. As shown in Figure 17, in step S60A, the UE in the Old RAN node transitions to the RRC inactive state. In step S61A, the UE sends an RRCResumeRequest to the New RAN node using the Unique UE context ID. In step S62A, the New RAN node sends a Retrieve UE context request to the Old RAN node using the Unique UE context ID. In step S63A, the Old RAN node identifies the UE context based on the Unique UE context ID and sends a Retrieve UE context response containing the identified UE context to the New RAN node. In step S64A, the New RAN node sends an RRCResume to the UE.

[0095] In option 2-2-1, "using a Unique UE context ID" may be interpreted as "including a Unique UE context ID."

[0096] In option 2-2-1, since RRCResumeRequest is sent by an unsecured SRB (Signaling Radio Bearer) 0, the Unique UE context ID included in RRCResumeRequest may be a Short unique UE context ID. A Short unique UE context ID may be composed of a portion of the bit sequence that makes up the Unique UE context ID.

[0097] Option 2-2-2 primarily describes the operation between the RAN node and the higher-level node. As shown in Figure 18, in step S70A, the UE in the Old RAN node transitions to the RRC inactive state. In step S71A, the UE sends an RRCResumeRequest to the New RAN node using the Unique UE context ID. In step S72A, the New RAN node sends a Retrieve UE context request to the higher-level node using the Unique UE context ID. In step S73A, the higher-level node identifies the UE context based on the Unique UE context ID and sends a Retrieve UE context response containing the identified UE context to the New RAN node. In step S74A, the New RAN node sends an RRCResume to the UE.

[0098] In option 2-2-2, "using a Unique UE context ID" may be interpreted as "including a Unique UE context ID."

[0099] In Option 2-2-2, since the RRCResumeRequest is sent by an unsecured SRB (Signaling Radio Bearer) 0, the Unique UE context ID included in the RRCResumeRequest may be a Short unique UE context ID. A Short unique UE context ID may be composed of some bit sequences that make up the Unique UE context ID. For example, in Option 1 shown in Figure 8, the Short unique UE context ID may include the New UE context ID. For example, in Option 1 shown in Figure 8, the Short unique UE context ID may include the Cell ID and C-RNTI (or I-RNTI).

[0100] (4.3) Operation Example 3 Operation Example 3 describes the operation of Handover, Dual connectivity, and Split configurations. Operation Example 3 may also be an example of operation that assumes the Unique UE context ID described in Operation Example 1. The following options are possible for Operation Example 3.

[0101] Option 3-1 describes the behavior related to Handover. The following options are possible for Option 3-1.

[0102] Option 3-1-1 describes the notification of the Unique UE context ID. As shown in Figure 19, in step S80, the Source RAN node sends a Handover request to the Target RAN node using the Unique UE context ID. In step S81, the Target RAN node sends a Handover request Ack to the Source RAN node.

[0103] Option 3-1-2 describes how to obtain the UE context. As shown in Figure 20, in step S90, the Source RAN node sends a Handover request to the Target RAN node using the Unique UE context ID. In step S91, the Target RAN node sends a UE context query to the higher-level node using the Unique UE context ID. In step S92, the higher-level node identifies the UE context based on the Unique UE context ID and sends the identified UE context to the Target RAN node. In step S93, the Target RAN node sends a Handover request Ack to the Source RAN node.

[0104] In option 3-1, "using a Unique UE context ID" may be interpreted as "including a Unique UE context ID."

[0105] Option 3-2 describes the operation of Dual connectivity. Specifically, it describes the procedure for adding a second node (SN) to Dual connectivity. The following options are possible for Option 3-2.

[0106] Option 3-2-1 describes the notification of the Unique UE context ID. As shown in Figure 21, in step S80A, the MN sends an S-Node Addition request to the SN using the Unique UE context ID. In step S81A, the SN sends an S-Node Addition request Ack to the MN.

[0107] Option 3-2-2 describes the acquisition of the UE context. As shown in Figure 22, in step S90A, the MN sends an S-Node Addition request to the SN using the Unique UE context ID. In step S91A, the SN sends a UE context query to the higher-level node using the Unique UE context ID. In step S92A, the higher-level node identifies the UE context based on the Unique UE context ID and sends the identified UE context to the SN. In step S93A, the SN sends an S-Node Addition request Ack to the MN.

[0108] In option 3-2, "using a Unique UE context ID" may be interpreted as "including a Unique UE context ID."

[0109] Option 3-3 describes the operation of the Split configuration. The following options are possible for Option 3-3.

[0110] Option 3-3-1 describes the notification of the Unique UE context ID. As shown in Figure 23, in step S80B, the CU sends a UE context setup request to the DU using the Unique UE context ID. In step S81B, the DU sends a UE context setup response to the CU.

[0111] Option 3-3-2 describes the acquisition of the UE context. As shown in Figure 24, in step S90B, the CU sends a UE context setup request to the DU using the Unique UE context ID. In step S91B, the DU sends a UE context query to the higher-level node using the Unique UE context ID. In step S92B, the higher-level node identifies the UE context based on the Unique UE context ID and sends the identified UE context to the DU. In step S93B, the DU sends a UE context setup response to the CU.

[0112] In option 3-3, "using a Unique UE context ID" may be interpreted as "including a Unique UE context ID."

[0113] (4.4) Other Two or more RAN nodes (i.e., RAN node set or RAN node group) that identify the UE context by a Unique UE context ID may be set for each UE type, or they may be set by the operator of the radio communication system 10 (e.g., OAM). The UE type may be a UE type (UE power class) as defined in 3GPP TS38.101.

[0114] (5) Operation and Effects In the embodiment, a new concept called Unique UE context ID is introduced to identify the UE context in two or more RAN nodes. With this configuration, the UE context can be appropriately shared between RAN nodes, and the delay associated with acquiring the UE context can be suppressed.

[0115] In this embodiment, a new concept called a RAN node set (or RAN node group) is introduced for two or more RAN nodes that identify a UE context by a Unique UE context ID. With this configuration, the complexity associated with managing UE contexts can be reduced by defining the scope within which a UE context is identified by a Unique UE context ID.

[0116] In this embodiment, the transmission and reception of RAN node set IDs (or RAN node group IDs) is performed between RAN nodes or between a RAN node and a higher-level node (Example 1). With this configuration, RAN nodes can appropriately obtain the RAN node set ID. By obtaining the RAN node set ID, RAN nodes can identify the Unique UE context ID.

[0117] In this embodiment, the sending and receiving of Unique UE context IDs is performed between RAN nodes or between a RAN node and a higher-level node (Operation Example 1). With this configuration, the RAN node can appropriately obtain the Unique UE context ID.

[0118] In this embodiment, during RRC Reestablishment or RRC Resume, the New RAN node obtains the UE context by sending a Unique UE context ID (Example 2). With this configuration, delays associated with obtaining the UE context can be suppressed during RRC Reestablishment or RRC Resume.

[0119] In this embodiment, during Handover or Dual connectivity (SN addition), the Target RAN node obtains the UE context by sending a Unique UE context ID (Operation Example 3). With this configuration, the operation associated with the new concept of Unique UE context ID is clarified during Handover or Dual connectivity (SN addition), and the delay associated with obtaining the UE context can be suppressed.

[0120] In one embodiment, in a CU / DU split configuration, the DU obtains the UE context by sending a Unique UE context ID (Operation Example 3). With this configuration, the operation associated with the new concept of Unique UE context ID is clarified, and the delay associated with obtaining the UE context can be suppressed.

[0121] (6) Other Embodiments Although the contents of the present invention have been described above in accordance with the embodiments, it will be obvious to those skilled in the art that the present invention is not limited to these descriptions and that various modifications and improvements are possible.

[0122] Although not specifically mentioned in the disclosure above, which of Operation Examples 1 to 3 is used (hereinafter, which mode is used) may be set by a higher-layer parameter. Which of the options in Operation Examples 1 to 3 is used (hereinafter, which mode is used) may be set by a higher-layer parameter. Which mode is supported may be reported by UE200 as UE capability(ies). Which mode is used may be predefined in the wireless communication system 20. Which mode is used may be set by a higher-layer parameter and reported by UE200 as UE capability(ies).

[0123] Although not specifically mentioned in the disclosure above, the following UE capability(ies) may be defined. UE capability(ies) may be defined for each UE200, for each FR, or for each FC. UE capability(ies) may be included in the signals reported from the UE200 to the gNB100, or in the signals (RRC configuration) set from the NB100 to the UE200.

[0124] In the disclosures above, configure, activate, update, indicate, enable, specify, and select may be interpreted as interchangeable. Similarly, link, associate, correspond, and map may be interpreted as interchangeable, and allocate, assign, monitor, and map may also be interpreted as interchangeable.

[0125] Furthermore, "specific," "dedicated," "UE specific," and "UE individual" may be interpreted interchangeably. Similarly, "common," "shared," "group-common," "UE common," and "UE shared" may be interpreted interchangeably.

[0126] The block diagrams (Figures 4 and 5) used in the description of the embodiments above show functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or it may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wired or wireless connections). A functional block may be realized by combining the above one device or the above multiple devices with software.

[0127] Functions include, but are not limited to, judgment, decision, determination, calculation, calculation, processing, derivation, investigation, exploration, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, assumption, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating (mapping), and assigning. For example, a functional block (configuration part) that enables transmission is called a transmitting unit or transmitter. In any case, as mentioned above, the method of implementation is not particularly limited.

[0128] Furthermore, the network device 50 and UE200 (the device) described above may function as a computer that processes the wireless communication method of this disclosure. Figure 25 is a diagram showing an example of the hardware configuration of the device. As shown in Figure 25, the device may be configured as a computer device including a processor 1001, memory 1002, storage 1003, communication device 1004, input device 1005, output device 1006, and bus 1007.

[0129] In the following explanation, the term "device" can be replaced with "circuit," "device," "unit," etc. The hardware configuration of the device may include one or more of the devices shown in the diagram, or it may be configured to omit some of the devices.

[0130] Each functional block of the device (see Figures 4 and 5) is implemented by any hardware element of the computer device, or a combination of such hardware elements.

[0131] Furthermore, each function in the device is realized by loading predetermined software (programs) onto hardware such as the processor 1001 and memory 1002, which allows the processor 1001 to perform calculations, control communication by the communication device 1004, and control at least one of the reading and writing of data in the memory 1002 and storage 1003.

[0132] The processor 1001 controls the entire computer, for example, by running an operating system. The processor 1001 may consist of a central processing unit (CPU) that includes interfaces with peripheral devices, control units, arithmetic units, registers, and so on.

[0133] Furthermore, the processor 1001 reads programs (program code), software modules, data, etc., from at least one of the storage 1003 and the communication device 1004 into the memory 1002 and executes various processes accordingly. The program used is one that causes the computer to execute at least a part of the operations described in the above embodiment. Moreover, the above-mentioned various processes may be executed by one processor 1001, or by two or more processors 1001 simultaneously or sequentially. The processor 1001 may be implemented by one or more chips. The program may also be transmitted from a network via a telecommunications line.

[0134] Memory 1002 is a computer-readable recording medium and may consist of at least one of the following: Read Only Memory (ROM), Erasable Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), Random Access Memory (RAM), etc. Memory 1002 may also be called a register, cache, main memory, etc. Memory 1002 can store a program (program code), software module, etc., that can execute a method according to one embodiment of this disclosure.

[0135] Storage 1003 is a computer-readable recording medium and may consist of at least one of the following: an optical disc such as a Compact Disc ROM (CD-ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., Compact Disc, Digital Multipurpose Disc, Blu-ray® Disc), a smart card, flash memory (e.g., a card, stick, key drive), a floppy® disk, a magnetic strip, etc. Storage 1003 may also be called an auxiliary storage device. The recording medium described above may also be, for example, a database, server, or other suitable medium including at least one of memory 1002 and storage 1003.

[0136] The communication device 1004 is hardware (transceiver / receiver device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as a network device, network controller, network card, communication module, etc.

[0137] The communication device 1004 may be configured to include, for example, a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc., in order to implement at least one of frequency division duplex (FDD) and time division duplex (TDD).

[0138] The input device 1005 is an input device that accepts input from an external source (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.). The output device 1006 is an output device that outputs to an external source (e.g., a display, speaker, LED lamp, etc.). The input device 1005 and the output device 1006 may be configured as an integrated unit (e.g., a touch panel).

[0139] Furthermore, each device, such as the processor 1001 and the memory 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or different buses may be configured for each device.

[0140] Furthermore, the device may include hardware such as a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic device (PLD), and a field programmable gate array (FPGA), and some or all of the functional blocks may be implemented by such hardware. For example, processor 1001 may be implemented using at least one of these hardware components.

[0141] Furthermore, notification of information is not limited to the embodiments / models described herein and may be carried out by other means. For example, notification of information may be carried out by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), upper layer signaling (e.g., RRC signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block (MIB), System Information Block (SIB))), other signals, or combinations thereof. RRC signaling may also be called RRC messages, and may be, for example, RRC Connection Setup messages, RRC Connection Reconfiguration messages, etc.

[0142] Each aspect / embodiment described herein may be applied to at least one of the following: Long Term Evolution (LTE), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, 4th generation mobile communication system (4G), 5th generation mobile communication system (5G), 6th generation mobile communication system (6G), xth generation mobile communication system (xG) (where x is, for example, an integer or decimal), Future Radio Access (FRA), New Radio (NR), W-CDMA®, GSM®, CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi®), IEEE 802.16 (WiMAX®), IEEE 802.20, Ultra-WideBand (UWB), Bluetooth®, and other appropriate systems, as well as next-generation systems extended based thereon. Furthermore, multiple systems may be applied in combination (for example, a combination of at least one of LTE and LTE-A with 5G).

[0143] The processing procedures, sequences, flowcharts, etc., of each aspect / embodiment described herein may be reordered, provided they are consistent with each other. For example, the methods described herein present various step elements in an exemplary order and are not limited to that specific order.

[0144] The specific operations described in this disclosure as being performed by a base station may, in some cases, be performed by its upper node. In a network consisting of one or more network nodes having a base station, it is clear that various operations performed for communication with a terminal can be performed by the base station and at least one other network node (for example, an MME or S-GW, but not limited to these). Although the above example illustrates a case where there is one other network node besides the base station, it may also be a combination of multiple other network nodes (for example, an MME and an S-GW).

[0145] Information and signals (such as data) can be output from a higher layer (or lower layer) to a lower layer (or higher layer). Input and output may occur via multiple network nodes.

[0146] Input and output information may be stored in a specific location (e.g., memory) or managed using a management table. Input and output information may be overwritten, updated, or appended to. Output information may be deleted. Input information may be sent to other devices.

[0147] The determination may be made by a value represented by one bit (0 or 1), by a boolean value (true or false), or by a numerical comparison (for example, by comparing with a predetermined value).

[0148] Each aspect / embodiment described herein may be used individually, in combination, or switched between as needed during implementation. Furthermore, notification of specific information (e.g., notification that "X is") is not limited to explicit notification, but may also be implicit (e.g., by not providing such notification).

[0149] Software should be broadly interpreted to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, execution threads, procedures, functions, and so on, whether they are called software, firmware, middleware, microcode, hardware description languages, or by any other name.

[0150] Furthermore, software, instructions, information, etc., may be transmitted and received via a transmission medium. For example, if software is transmitted from a website, server, or other remote source using at least one of wired technology (such as coaxial cable, fiber optic cable, twisted pair, or Digital Subscriber Line (DSL)) and wireless technology (such as infrared or microwave), then at least one of these wired and wireless technologies is included in the definition of a transmission medium.

[0151] The information, signals, etc. described in this disclosure may be represented using any of the various different technologies. For example, the data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0152] In addition, terms used in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of the channel and symbol may be a signal (signaling). Also, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, cell, frequency carrier, etc.

[0153] The terms “system” and “network” as used in this disclosure are interchangeable.

[0154] Furthermore, the information, parameters, etc., described in this disclosure may be expressed using absolute values, relative values ​​from a given value, or other corresponding information. For example, wireless resources may be indicated by an index.

[0155] The names used for the parameters described above are not restrictive in any way. Furthermore, the formulas and other expressions using these parameters may differ from those expressly disclosed in this disclosure. Since various channels (e.g., PUCCH, PDCCH, etc.) and information elements can be identified by any suitable name, the various names assigned to these various channels and information elements are not restrictive in any way.

[0156] In this disclosure, terms such as "Base Station (BS)," "wireless base station," "fixed station," "NodeB," "eNodeB (eNB)," "gNodeB (gNB)," "access point," "transmission point," "reception point," "transmission / reception point," "cell," "sector," "cell group," "carrier," and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0157] A base station can house one or more (e.g., three) cells (also called sectors). If a base station houses multiple cells, the entire coverage area of ​​the base station can be divided into multiple smaller areas, each of which can also be provided with communication services by a base station subsystem (e.g., a small indoor base station (Remote Radio Head: RRH)).

[0158] The terms "cell" or "sector" refer to a portion or all of the coverage area of ​​at least one of the base stations and base station subsystems that provide communication services in this coverage.

[0159] In this disclosure, the transmission of information by a base station to a terminal may be interpreted as the base station instructing the terminal to perform control or operation based on the information.

[0160] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0161] A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or several other appropriate terms.

[0162] At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may be a device mounted on a mobile body, the mobile body itself, etc. The mobile body may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile body (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). At least one of the base station and the mobile station may be a device that does not necessarily move during communication operation. For example, at least one of the base station and the mobile station may be an Internet of Things (IoT) device such as a sensor.

[0163] Furthermore, the term "base station" in this disclosure may be interpreted as "mobile station" (user terminal, hereinafter the same). For example, each aspect / embodiment of this disclosure may be applied to a configuration in which communication between a base station and a mobile station is replaced with communication between multiple mobile stations (which may be called, for example, Device-to-Device (D2D), Vehicle-to-Everything (V2X), etc.). In this case, the mobile station may have the functions that a base station has. Also, terms such as "uplink" and "downlink" may be interpreted as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, uplink channel, downlink channel, etc. may be interpreted as side channel.

[0164] Similarly, the term "mobile station" in this disclosure may be interpreted as "base station." In this case, the base station may be configured to have the functions that a mobile station has.

[0165] A wireless frame may consist of one or more frames in the time domain. Each of these frames in the time domain may be called a subframe.

[0166] A subframe may further consist of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0167] Numerology may be communication parameters applied to at least one of the transmission and reception of a signal or channel. Numerology may include, for example, at least one of the following: subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame configuration, specific filtering processes performed by the transceiver in the frequency domain, and specific windowing processes performed by the transceiver in the time domain.

[0168] A slot may consist of one or more symbols in the time domain (such as Orthogonal Frequency Division Multiplexing (OFDM) symbols or Single Carrier Frequency Division Multiple Access (SC-FDMA) symbols). A slot may also be a time unit based on neurology.

[0169] A slot may include multiple mini-slots. Each mini-slot may consist of one or more symbols in the time domain. Mini-slots may also be called sub-slots. Mini-slots may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a mini-slot may be called a PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a mini-slot may be called a PDSCH (or PUSCH) mapping type B.

[0170] Wireless frames, subframes, slots, minislots, and symbols all represent units of time when transmitting a signal. Different names may be used for each of these terms.

[0171] For example, one subframe may be called a transmission time interval (TTI), multiple consecutive subframes may be called a TTI, or one slot or one minislot may be called a TTI. In other words, at least one of a subframe and a TTI may be a subframe (1 ms) in existing LTE, a period shorter than 1 ms (e.g., 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be called a slot, minislot, etc., instead of a subframe.

[0172] Here, TTI refers to, for example, the smallest unit of time for scheduling in wireless communication. For example, in an LTE system, the base station schedules each user terminal to allocate wireless resources (such as the frequency bandwidth and transmission power available to each user terminal) in TTI units. However, the definition of TTI is not limited to this.

[0173] TTI may be a transmission time unit for channel-encoded data packets (transport blocks), code blocks, code words, etc., or it may be a processing unit for scheduling, link adaptation, etc. Note that when a TTI is given, the actual time interval (e.g., number of symbols) in which the transport block, code block, code word, etc. are mapped may be shorter than the given TTI.

[0174] Furthermore, if one slot or one mini-slot is referred to as TTI, then one or more TTIs (i.e., one or more slots or one or more mini-slots) may constitute the minimum time unit of scheduling. In addition, the number of slots (number of mini-slots) that constitute the minimum time unit of scheduling may be controlled.

[0175] A TTI with a time length of 1ms may also be called a normal TTI, long TTI, normal subframe, long subframe, slot, etc. A TTI shorter than a normal TTI may also be called a shortened TTI, short TTI, partial or fractional TTI, shortened subframe, short subframe, mini slot, sub slot, slot, etc.

[0176] Furthermore, long TTIs (e.g., normal TTIs, subframes, etc.) may be interpreted as TTIs with a time length exceeding 1 ms, and short TTIs (e.g., shortened TTIs, etc.) may be interpreted as TTIs with a TTI length less than that of a long TTI but 1 ms or more.

[0177] A resource block (RB) is a resource allocation unit in the time domain and frequency domain, and in the frequency domain, it may contain one or more consecutive subcarriers. The number of subcarriers in an RB may be the same regardless of the neurology, for example, 12. The number of subcarriers in an RB may be determined based on the neurology.

[0178] Furthermore, the time domain of RB may contain one or more symbols and may be the length of one slot, one minislot, one subframe, or one TTI. One TTI, one subframe, etc., may each consist of one or more resource blocks.

[0179] One or more RBs may also be called Physical RBs (PRBs), Sub-Carrier Groups (SCGs), Resource Element Groups (REGs), PRB pairs, RB pairs, etc.

[0180] Furthermore, a resource block may consist of one or more resource elements (REs). For example, one RE may be a radio resource area comprising one subcarrier and one symbol.

[0181] A Bandwidth Part (BWP), also known as a partial bandwidth, may represent a subset of consecutive common resource blocks (RBs) for a given neurology in a given carrier. Here, the common RBs may be identified by an index of the RBs relative to the carrier's common reference point. PRBs may be defined and numbered within a given BWP.

[0182] A BWP may include BWPs for UL (UL BWP) and BWPs for DL ​​(DL BWP). One or more BWPs may be configured within a single carrier for a UE.

[0183] At least one of the configured BWPs may be active, and the UE does not need to assume that it will send or receive a given signal / channel outside of the active BWP. In this disclosure, terms such as "cell" and "carrier" may be read as "BWP".

[0184] The structures described above, such as wireless frames, subframes, slots, minislots, and symbols, are merely illustrative. For example, the number of subframes included in a wireless frame, the number of slots per subframe or wireless frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, and the number of symbols, symbol length, and cyclic prefix (CP) length within a TTI can be varied in various ways.

[0185] The terms “connected,” “coupled,” or any variation thereof, mean any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are “connected” or “coupled” with each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, “connection” may be read as “access.” As used in this disclosure, two elements may be considered to be “connected” or “coupled” with each other using at least one of one or more wires, cables, and printed electrical connections, and, in some non-limiting and non-exclusive examples, electromagnetic energy having wavelengths in the radio frequency domain, microwave domain, and optical (both visible and invisible) domain.

[0186] The reference signal can also be abbreviated as Reference Signal (RS), and may be called a pilot depending on the applicable standard.

[0187] In this disclosure, the phrase "based on" does not mean "based solely on" unless otherwise specified. In other words, the phrase "based on" means both "based solely on" and "based at least on."

[0188] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0189] Any reference to elements using designations such as “First,” “Second,” etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements. Accordingly, references to the First and Second elements do not imply that only two elements may be employed therein, or that the First element must precede the Second element in any way.

[0190] Where the terms “include,” “including,” and variations thereof are used in this disclosure, these terms are intended to be inclusive, as is the term “comprising.” Furthermore, the term “or” as used in this disclosure is not intended to mean exclusive OR.

[0191] In this disclosure, if articles are added through translation, such as a, an, and the in English, this disclosure may include the fact that the noun following these articles is plural.

[0192] As used in this disclosure, the terms “determining” and “determining” may encompass a wide variety of actions. “Determining” may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, or inquiring (e.g., searching in a table, database, or other data structure), or ascertaining. “Determining” may also include receiving (e.g., receiving information), transmitting (e.g., sending information), inputting, outputting, or accessing (e.g., accessing data in memory). Furthermore, "judgment" and "decision" can include considering something as having been "judged" or "decided" after resolving, selecting, choosing, establishing, comparing, etc. In other words, "judgment" and "decision" can include considering something as having been "judged" or "decided" after some action. Also, "judgment (decision)" can be reinterpreted as "assuming," "expecting," or "considering."

[0193] In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combine" may be interpreted similarly to "different."

[0194] Figure 26 shows an example of the configuration of vehicle 2001. As shown in Figure 26, vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021 to 2029, an information service unit 2012, and a communication module 2013.

[0195] The drive unit 2002 is composed of, for example, an engine, a motor, or a hybrid of an engine and a motor.

[0196] The steering unit 2003 includes at least a steering wheel (also called a handle) and is configured to steer at least one of the front wheels and the rear wheels based on the operation of the steering wheel, which is operated by the user.

[0197] The electronic control unit 2010 consists of a microprocessor 2031, memory (ROM, RAM) 2032, and communication ports (IO ports) 2033. Signals from various sensors 2021 to 2027 installed in the vehicle are input to the electronic control unit 2010. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

[0198] Signals from various sensors 2021 to 2028 include current signals from the current sensor 2021 that senses motor current, front and rear wheel rotation speed signals obtained by the rotation speed sensor 2022, front and rear wheel air pressure signals obtained by the air pressure sensor 2023, vehicle speed signals obtained by the vehicle speed sensor 2024, acceleration signals obtained by the acceleration sensor 2025, accelerator pedal depression signals obtained by the accelerator pedal sensor 2029, brake pedal depression signals obtained by the brake pedal sensor 2026, shift lever operation signals obtained by the shift lever sensor 2027, and detection signals obtained by the object detection sensor 2028 for detecting obstacles, vehicles, pedestrians, etc.

[0199] The Information Services Unit 2012 consists of various devices for providing various types of information, such as driving information, traffic information, and entertainment information, including a car navigation system, audio system, speakers, television, and radio, and one or more ECUs that control these devices. The Information Services Unit 2012 uses information acquired from external devices via a communication module 2013, etc., to provide various multimedia information and multimedia services to the occupants of Vehicle 1.

[0200] The driver assistance system unit 2030 consists of various devices that provide functions to prevent accidents or reduce the driver's workload, such as millimeter-wave radar, LiDAR (Light Detection and Ranging), cameras, positioning locators (e.g., GNSS), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps), gyro systems (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System)), AI (Artificial Intelligence) chips, and AI processors, as well as one or more ECUs that control these devices. The driver assistance system unit 2030 also sends and receives various information via the communication module 2013 to realize driver assistance functions or autonomous driving functions.

[0201] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 1 via its communication port. For example, the communication module 2013 sends and receives data via the communication port 2033 between the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, axle 2009, the microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021 to 2028 provided in the vehicle 2001.

[0202] The communication module 2013 is a communication device that can be controlled by the microprocessor 2031 of the electronic control unit 2010 and can communicate with external devices. For example, it can send and receive various types of information to and from external devices via wireless communication. The communication module 2013 may be located either inside or outside the electronic control unit 2010. The external device may be, for example, a base station or a mobile station.

[0203] The communication module 2013 transmits current signals from current sensors input to the electronic control unit 2010 to an external device via wireless communication. The communication module 2013 also transmits, via wireless communication, other signals input to the electronic control unit 2010, including front and rear wheel rotation speed signals obtained by the rotation speed sensor 2022, front and rear wheel air pressure signals obtained by the air pressure sensor 2023, vehicle speed signals obtained by the vehicle speed sensor 2024, acceleration signals obtained by the acceleration sensor 2025, accelerator pedal depression signals obtained by the accelerator pedal sensor 2029, brake pedal depression signals obtained by the brake pedal sensor 2026, shift lever operation signals obtained by the shift lever sensor 2027, and detection signals obtained by the object detection sensor 2028 for detecting obstacles, vehicles, pedestrians, etc.

[0204] The communication module 2013 receives various information (traffic information, signal information, distance information, etc.) transmitted from external devices and displays it on the information service unit 2012 installed in the vehicle. The communication module 2013 also stores the various information received from external devices in memory 2032, which is available to the microprocessor 2031. Based on the information stored in memory 2032, the microprocessor 2031 may control the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, left and right front wheels 2007, left and right rear wheels 2008, axles 2009, sensors 2021 to 2028, etc., installed in the vehicle 2001.

[0205] Although the present disclosure has been described in detail above, it will be clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the intent and scope of the present disclosure as defined by the claims. Therefore, the descriptions in the present disclosure are illustrative and not intended to be restrictive in any way.

[0206] (Note) The disclosure described above may also be expressed as follows:

[0207] The first feature is a terminal comprising: a control unit that controls at least one of re-establishing to a second network device or returning to the second network device when connected to a first network device; and a transmission unit that transmits at least one of a message requesting re-establishment to the second network device or a message requesting return to the second network device, using identification information that identifies the terminal context in two or more network devices including the first network device and the second network device.

[0208] The second feature is a network device comprising a storage unit for storing terminal contexts and a transmission unit for transmitting identification information to identify the terminal contexts in the two or more network devices.

[0209] The third feature is a network device comprising: a receiving unit that receives identification information for identifying a terminal context in two or more network devices; and a control unit that acquires the terminal context by transmitting the identification information to other network devices.

[0210] The fourth feature is that, in the third feature, the control unit is a network device that acquires the terminal context in at least one of the following procedures: a re-establishment procedure for the network device, a recovery procedure for the network device, a handover procedure for the network device, or a procedure for adding the network device as the second node of dual connectivity.

[0211] The fifth feature is a wireless communication system comprising a terminal, a first network device, and a second network device, wherein the terminal, when connected to the first network device, includes a control unit that controls at least one of re-establishing to the second network device or returning to the second network device, and a transmission unit that transmits at least one of a message requesting re-establishment to the second network device or a message requesting return to the second network device using identification information that identifies the terminal context in two or more network devices including the first network device and the second network device.

[0212] The sixth feature is a wireless communication method comprising: the step of controlling at least one of re-establishing to a second network device or returning to the second network device when connected to a first network device; and the step of transmitting at least one of a message requesting re-establishment to the second network device or a message requesting return to the second network device using identification information that identifies the terminal context in two or more network devices including the first network device and the second network device.

[0213] 10 Wireless Communication System 10A First Network 10B Second Network 20A, 20B Wireless Access Network 30A, 30B Core Network 50 Network Device 51 Receiving Unit 52 Transmitting Unit 53 Control Unit 100A, 100B Base Station 200 UE 210 Wireless Signal Transmitting / Receiving Unit 220 Amplifier Unit 230 Modulation / Demodulation Unit 240 Control Signal / Reference Signal Processing Unit 250 Encoding / Decoding Unit 260 Data Transmitting / Receiving Unit 270 Control Unit 1001 Processor 1002 Memory 1003 Storage 1004 Communication Device 1005 Input Device 1006 Output Device 1007 Bus 2001 Vehicle 2002 Drive Unit 2003 Steering Unit 2004 Accelerator Pedal 2005 Brake Pedal 2006 Shift Lever 2007 Front wheels (left and right) 2008 Rear wheels (left and right) 2009 Axle 2010 Electronic control unit 2012 Information service unit 2013 Communication module 2021 Current sensor 2022 Rotation speed sensor 2023 Air pressure sensor 2024 Vehicle speed sensor 2025 Acceleration sensor 2026 Brake pedal sensor 2027 Shift lever sensor 2028 Object detection sensor 2029 Accelerator pedal sensor 2030 Driving assistance system unit 2031 Microprocessor 2032 Memory (ROM, RAM) 2033 Communication port

Claims

1. A terminal comprising: a control unit that controls at least one of re-establishing to a second network device or returning to the second network device when connected to a first network device; and a transmission unit that transmits at least one of a message requesting re-establishment to the second network device or a message requesting return to the second network device, using identification information that identifies the terminal context in two or more network devices including the first network device and the second network device.

2. A network device comprising: a storage unit for storing terminal contexts; and a transmission unit for transmitting identification information to identify the terminal contexts in the two or more network devices.

3. A network device comprising: a receiving unit that receives identification information for identifying a terminal context in two or more network devices; and a control unit that obtains the terminal context by transmitting the identification information to other network devices.

4. The network device according to claim 3, wherein the control unit acquires the terminal context in at least one of the following procedures: a re-establishment procedure for the network device, a recovery procedure for the network device, a handover procedure for the network device, or a procedure for adding the network device as a second node of dual connectivity.

5. A wireless communication system comprising a terminal, a first network device, and a second network device, wherein the terminal, when connected to the first network device, includes a control unit that controls at least one of re-establishing to the second network device or returning to the second network device, and a transmission unit that transmits at least one of a message requesting re-establishment to the second network device or a message requesting return to the second network device, using identification information that identifies the terminal context in two or more network devices including the first network device and the second network device.

6. A wireless communication method comprising: a step of controlling at least one of re-establishing to a second network device or returning to the second network device when connected to a first network device; and a step of transmitting at least one of a message requesting re-establishment to the second network device or a message requesting return to the second network device using identification information that identifies the terminal context in two or more network devices including the first network device and the second network device.

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