WO2025203620A1 - Terminal and base station - Google Patents

Abstract

This terminal is provided with: a control unit that operates by switching between a first mode that enables simultaneous connection to a first cell provided by a first wireless base station and a second cell provided by a second wireless base station, and a second mode for connecting only to the second cell; and a transmission unit that transmits, to the second wireless base station, first mode information if the control unit is operating in the first mode, and transmits second mode information if the control unit is operating in the second mode.

Description

Terminals, base stations

This disclosure relates to a terminal that simultaneously connects to multiple networks and the base stations included in these networks.

The 3rd Generation Partnership Project (3GPP (registered trademark)) is developing specifications for the 5th generation mobile communication system (5G, also known as New Radio (NR) or Next Generation (NG)), and is also developing specifications for the next generation of mobile communication systems, known as Beyond 5G, 5G Evolution, or 6G.

The upcoming 6G wireless communication system is expected to realize ultra-high speed, high capacity communications, and ultra-multiple connections that exceed those of 5G (Non-Patent Document 1).

NTT Docomo, "Docomo 6G White Paper 5.0 Edition," [online], November 2022, [Retrieved March 15, 2024], Internet <URL: https://www.docomo.ne.jp/binary/pdf/corporate/technology/whitepaper_6g/DOCOMO_6G_White_PaperJP_20221116.pdf>

It is expected that 6G wireless communication systems will coexist with existing 5G wireless communication systems. Therefore, terminals (hereinafter also referred to as user equipment (UE)) will be able to simultaneously connect to base stations that comply with the 5G radio access technology (RAT) (hereinafter also referred to as 5G RAN nodes or 5G nodes) and base stations that comply with the 6G RAT (hereinafter also referred to as 6G RAN nodes or 6G nodes).

Simultaneous connection to multiple nodes belonging to different radio access technologies (RATs), such as 5G and 6G nodes, is called Multi-Radio DC (MR-DC), a type of dual connectivity (DC). A UE that runs MR-DC has a protocol stack consisting of a physical layer, medium access control (MAC) layer, radio resource control (RRC) layer, etc., for each RAT that MR-DC supports. In other words, a UE that runs MR-DC has two protocol stacks corresponding to the two RATs. A mode in which both protocol stacks are enabled is called dual stack mode, and a mode in which only one is enabled is called single stack mode. In other words, a UE can run MR-DC when operating in dual stack mode.

By the way, for example, if a UE connected to a 6G node moves, the quality of the 6G cell provided by the 6G node may deteriorate. In this case, the UE reports the deterioration in the quality of the 6G cell to the 6G node. In response to this report, if the 6G node recognizes that the UE is performing MR-DC (connected not only to a 6G cell but also to a 5G cell provided by a 5G node), it may instruct the UE to release the 6G cell.

However, depending on the network architecture, there may not be a direct interface between the 5G node and the 6G node, and the 6G node may not be able to recognize that the UE is connected to both a 6G cell and a 5G cell. In this case, the 6G node may request an inter-RAT HO to the 5G cell to which the UE is currently connected, for example via the core network (CN). Such an HO request is not only ineffective, but also wastes resources by requiring many more processes than cell release.

The present disclosure therefore aims to provide a terminal that can share the connection status of a terminal between a 5G node and a 6G node, receive appropriate HO instructions, and a base station that can issue such instructions.

One aspect of the disclosure is a terminal comprising: a control unit (control unit 270) that switches between a first mode that enables simultaneous connection to a first cell provided by a first radio base station and a second cell provided by a second radio base station, and a second mode that connects only to the second cell; and a transmission unit (radio signal transmission/reception unit 210) that transmits first mode information to the second radio base station when the control unit is operating in the first mode, and transmits second mode information to the second radio base station when the control unit is operating in the second mode.

One aspect of the disclosure is a base station comprising: a receiver (radio signal transceiver 110) that receives first mode information from a terminal when the terminal is operating in a first mode that enables simultaneous connection to a first cell provided by another base station and a second cell provided by the base station; and receives second mode information when the terminal is operating in a second mode that connects only to the second cell; and a transmitter (radio signal transceiver 110) that transmits to the terminal an instruction to release the second cell based on the first mode information, and an instruction to measure the reception quality of the first cell based on the second mode information.

FIG. 1 is a diagram showing the overall schematic configuration of a wireless communication system. FIG. 2 is a diagram showing frequency ranges used in wireless communication systems. FIG. 3 is a diagram showing an example of the configuration of a radio frame, a subframe, a slot, and a symbol used in a radio communication system. FIG. 4 is a functional block diagram of the terminal. FIG. 5 is a functional block diagram of a base station. Figure 6 shows an example of the architecture of 5G Radio Access Technology (5G RAT) and 6G RAT. Figure 7 shows an example of the architecture of 5G RAT and 6G RAT. Figure 8 shows an example of a protocol stack for a terminal that connects simultaneously to 5G RAN and 6G RAN. FIG. 9 is a diagram showing an example of a mobile terminal connected to multiple RATs. FIG. 10 is a diagram showing an example of a mobile terminal connected to multiple RATs. Figure 11 shows an example of a terminal connected to the 6G RAT moving. Figure 12 is a sequence diagram showing an example of a terminal sending a measurement report and stack mode to a 6G node. FIG. 13 is a sequence diagram showing an example of transmitting a measurement report and an HO report to a 6G node when a terminal performs intra-RAT HO based on an instruction from 5G. FIG. 14 is a sequence diagram illustrating an example of performing a cell change via a cooperative node. FIG. 15 is a diagram illustrating an example of a cooperative node provided between a 5G node and a 6G node. FIG. 16 is a diagram illustrating an example of a cooperative node provided between a 5G node and a 6G node. FIG. 17 is a diagram illustrating an example of a cooperative node provided between a 5G node and a 6G node. Figure 18 shows examples of architectures for 4G RAT, 5G RAT and 6G RAT. Figure 19 shows examples of architectures for 4G RAT, 5G RAT and 6G RAT. FIG. 20 is a diagram illustrating an example of the hardware configuration of a base station and a terminal. FIG. 21 is a diagram illustrating an example of the configuration of a vehicle.

The following describes embodiments based on the drawings. Note that identical or similar reference symbols are used to designate identical functions and configurations, and descriptions of these will be omitted where appropriate.

(1) Configuration of Wireless Communication System The wireless communication system 10 shown in FIG. 1 is a wireless communication system conforming to a method called 5G. On the other hand, the wireless communication system 10 may be a wireless communication system conforming to a method called Beyond 5G, 5G Evolution, or 6G. The wireless communication system 10 may be expressed as a Radio Access Technology (RAT). In this case, the wireless communication system 10 conforming to 5G may be expressed as a 5G RAT, and the wireless communication system 10 conforming to 6G may be expressed as a 6G RAT.

The wireless communication system 10 can support Massive Multiple-Input Multiple-Output (Massive MIMO), which generates more directional beams by controlling the wireless signals transmitted from multiple antenna elements, Carrier Aggregation (CA), which uses multiple component carriers (CC) as a bundle, and Dual Connectivity (DC), which enables simultaneous communication with two base stations.

As shown in Figure 1, the wireless communication system 10 includes a base station 100 (hereinafter also referred to as gNodeB (gNB) 100) that constitutes a Radio Access Network (RAN) 20, and a terminal 200 (hereinafter also referred to as user equipment (UE) 200) that performs wireless communication with the gNB 100. The RAN 20 is connected to a core network (CN) 30.

RAN20 may be, for example, 5G RAN 20A conforming to 5G, as shown in Figure 6, or 6G RAN 20B conforming to 6G. Note that gNB100 is not limited to referring to a base station constituting 5G RAN 20A, but may also refer to a base station constituting 6G RAN 20B. When distinguishing between the two, for example, as shown in Figure 9, the former may be expressed as 5G RAN node100A or 5G node 100A, and the latter may be expressed as 6G RAN node100B or 6G node 100B.

The CN30 is composed of multiple network functions (NFs). NFs are, for example, the Access and Mobility Management Function (AMF) 300 and the Network Data Analytics Function (NWDAF) 400. The AMF 300, for example, performs registration of the UE 200. The NWDAF 400, for example, performs optimization of the CN30. Furthermore, the CN30 may be, for example, a CN (5GC) 30A that complies with 5G, or a CN (6GC) 30B that complies with 6G, as shown in Figure 6.

The specific configuration of the wireless communication system 10, for example, the number of gNBs 100 and UEs 200, is not limited to the example shown in FIG. 1. Furthermore, the RAN 20 and CN 30 may simply be referred to as a "network."

The gNB100 may be a base station in a Centralized-Radio Access Network (C-RAN) configuration having a distributed unit (DU) with the function of connecting to the UE200, and a central unit (CU) with the function of connecting to the network. In this case, the gNB100 may be read as a DU, a CU, or both a DU and a CU. When the gNB100 is read as a DU, it may be called a gNB-DU. When the gNB100 is read as a CU, it may be called a gNB-CU. When the gNB100 is read as a DU and a CU, the DU portion may be called a gNB-DU and the CU portion may be called a gNB-CU.

The wireless communication system 10 may also support multiple frequency ranges (FR), i.e., the following FRs as shown in FIG.
・FR1: 410MHz to 7.125GHz
・FR2-1: 24.25GHz to 52.6GHz
・FR2-2: 52.6GHz to 71GHz
・FR3: 7.125GHz to 24.25GHz

In FR1, a subcarrier spacing (SCS) of 15, 30, or 60 kHz and a bandwidth (BW) of 5 to 100 MHz may be used. In FR2-1, an SCS of 60 or 120 kHz (or 240 kHz) and a BW of 50 to 400 MHz may be used.

In FR2-2, Cyclic Prefix-Orthogonal Frequency Division Multiplexing (CP-OFDM) or Discrete Fourier Transform-Spread-Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) with a larger SCS may be applied to avoid increased phase noise.

FR3 is a frequency band that fills the gap between FR1 and FR2-1, and may be called by a different name as long as it refers to the same frequency band. The BW and SCS for FR3 may be the same as those for FR1 or FR2-1, or different ones may be applied.

Furthermore, as shown in Figure 3, one slot in the wireless communication system 10 consists of 14 symbols. If this configuration is maintained, the larger (wider) the SCS, the shorter the symbol period (and slot period). Note that the SCS is not limited to the frequencies shown in Figure 3, and may be frequencies such as 480 kHz or 960 kHz.

Furthermore, the number of symbols that make up one slot does not necessarily have to be 14 symbols, and may be, for example, 28 or 56 symbols. Furthermore, the number of slots per subframe may differ depending on the SCS.

(2) Functional Block Configuration of Wireless Communication System (2.1) Functional Block Configuration of Terminal As shown in FIG. 4, the UE 200 includes a wireless signal transmitting/receiving 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 transmitting/receiving unit 260, and a control unit 270.

The radio signal transceiver 210 transmits and receives radio signals to and from the gNB100. The radio signal transceiver 210 may be configured with a transmitter that transmits radio signals to the gNB100 and a receiver that receives radio signals from the gNB100. The radio signals may include data or may be interpreted as data. Transmission may be interpreted as reporting, notification, etc. Reception may be interpreted as setting (is set), instruction (is given), notification (is given), etc. Note that setting may be realized by configuration information (information element (IE)) of the radio resource control (RRC) layer, and instruction may be realized by a control element (CE) or downlink control information (DCI) of the medium access control (MAC) layer.

In the embodiment, the radio signal transceiver 210 can notify the 6G node 100B of the stack mode in which the UE 200 (controller 270, described later) is operating. The UE 200 can switch between operating in a dual stack mode, which enables simultaneous connection to a 5G cell provided by the 5G node 100A and a 6G cell provided by the 6G node 100B, and a single stack mode, which connects to only one of the 5G cell or the 6G cell. Note that the dual stack mode may be referred to as the first mode, and the single stack mode may be referred to as the second mode. Furthermore, information notifying that the UE 200 is operating in the first mode may be referred to as first mode information, and information notifying that the UE 200 is operating in the second mode may be referred to as second mode information.

In other words, the radio signal transceiver 210 of the embodiment can transmit first mode information to the 6G node 100B when the UE 200 (controller 270, described later) is operating in the first mode. Similarly, the radio signal transceiver 210 can transmit second mode information to the 6G node 100B when the UE 200 (controller 270, described later) is operating in the second mode.

In this embodiment, the wireless signal transceiver unit 210 can receive an instruction to release the 6G cell provided by the 6G node 100B from the 6G node 100B that has received the first mode information.

In this embodiment, the wireless signal transceiver unit 210 can receive an instruction to measure the reception quality of the 5G cell provided by the 5G node 100A from the 6G node 100B that has received the second mode information. This instruction may be interpreted as an instruction to perform an inter-RAT HO from the 6G cell to the 5G cell.

The wireless signal transceiver 210 of the embodiment can receive from the 5G node 100A an instruction to measure the reception quality of a neighboring cell, which is another 5G cell adjacent to the 5G cell and provided by the 5G node 100A, and can further transmit the measurement results of this neighboring cell to the 5G node 100A and the 6G node 100B. Furthermore, the wireless signal transceiver 210 of the embodiment can receive from the 5G node 100A an HO instruction to this neighboring cell, and can further report to the 6G node 100B that the HO instruction has been received.

The amplifier unit 220 is composed of a power amplifier (PA)/low noise amplifier (LNA) etc. The amplifier unit 220 amplifies the radio signal output from the radio signal transmitting/receiving unit 210. The amplifier unit 220 also amplifies the radio signal output from the modulation/demodulation unit 230.

The modem unit 230 performs data modulation/demodulation, transmission power setting, resource block allocation, etc. for each specified communication destination (gNB100 or another gNB100). CP-OFDM/DFT-S-OFDM may be applied to the modem unit 230. Furthermore, DFT-S-OFDM may be used not only for the uplink (UL) but also for the downlink (DL).

The control signal/reference signal processing unit 240 performs processing related to control signals transmitted and received between the gNB 100, such as radio resource control (RRC) signaling.

The control signal/reference signal processing unit 240 performs processing related to reference signals transmitted and received between the gNB 100, such as Demodulation Reference Signal (DMRS), Phase Tracking Reference Signal (PTRS), Channel State Information-Reference Signal (CSI-RS), Sounding Reference Signal (SRS), and Positioning Reference Signal (PRS).

Note that channels include control channels and data channels. Control channels include the physical uplink control channel (PUCCH), physical downlink control channel (PDCCH), physical random access channel (PRACH), physical broadcast channel (PBCH), etc. Data channels include the physical uplink shared channel (PUSCH), physical downlink shared channel (PDSCH), etc.

The encoding/decoding unit 250 performs operations such as dividing/concatenating and coding/decoding the data contained in the wireless signal for each specified communication destination (gNB100 or another gNB100).

Specifically, the encoding/decoding unit 250 decodes the data output from the modulation/demodulation unit 230 and concatenates the decoded data. The encoding/decoding unit 250 also divides the data output from the data transmission/reception unit 260 into pieces of a predetermined size and performs coding on the divided data.

The data transmission/reception unit 260 performs tasks such as assembling and disassembling the data units (Protocol Data Unit (PDU)/Service Data Unit (SDU)) that make up the data between each layer. The multiple layers include the Medium Access Control (MAC) layer, Radio Link Control (RLC) layer, and Packet Data Convergence Protocol (PDCP) layer. The data transmission/reception unit 260 also performs data error correction and retransmission control based on Hybrid Automatic Repeat Request (HARQ).

The control unit 270 controls the UE 200. For example, the control unit 270 controls the transmission and reception of radio signals by the radio signal transmission and reception unit 210, the amplification by the amplifier unit 220, the data modulation/demodulation by the modem unit 230, the signal processing by the control signal and reference signal processing unit 240, the coding/decoding by the encoding/decoding unit 250, and the assembly/disassembly of data units by the data transmission and reception unit 260.

As described above, the control unit 270 of the embodiment can switch between operating in a dual stack mode, which enables simultaneous connection to a 5G cell provided by the 5G node 100A and a 6G cell provided by the 6G node 100B, and a single stack mode, which connects to only one of the 5G cell or the 6G cell. In other words, the control unit 270 can operate in either dual stack mode or single stack mode. When operating in dual stack mode, the control unit 270 may be considered to be executing MR-DC for the 5G cell and the 6G cell.

(2.2) Functional block configuration of base station As shown in Figure 5, the gNB100 includes a radio signal transceiver unit 110 and a control unit 120.

The radio signal transmitting/receiving unit 110 transmits and receives radio signals to and from the UE 200. The radio signal transmitting/receiving unit 110 may be configured with a transmitting unit that transmits radio signals to the UE 200 and a receiving unit that receives radio signals from the UE 200. The radio signals may include data or may be interpreted as data. Transmission may be interpreted as configuration, instruction, notification, etc. Reception may be interpreted as (being reported), notification, etc. Note that configuration may be realized by configuration information (information element (IE)) of the radio resource control (RRC) layer, and instructions may be realized by control elements (CE) and downlink control information (DCI) of the medium access control (MAC) layer.

The wireless signal transceiver 110 of this embodiment can receive information transmitted by the wireless signal transceiver 210 described above. The wireless signal transceiver 110 can also transmit information received by the wireless signal transceiver 210 described above.

For example, the radio signal transceiver 110 of the embodiment can receive first mode information from the UE 200 when the UE 200 is operating in a first mode (dual stack mode) that enables simultaneous connection to a 5G cell provided by the 5G node 100A and a 6G cell provided by the 6G node 100B, and can receive second mode information when the UE 200 is operating in a second mode (single stack mode) that connects to only one of the 5G cell or the 6G cell. Furthermore, the radio signal transceiver 110 of the embodiment can transmit to the UE 200 an instruction to release the 6G cell based on the first mode information, and an instruction to measure the reception quality of the 5G cell based on the second mode information.

The control unit 120 controls the gNB 100. The control unit 120 controls, for example, the transmission and reception of radio signals by the radio signal transmission and reception unit 110.

(3) Network Architecture in Dual Connectivity A network architecture in which the UE 200 connects simultaneously, that is, in which dual connectivity (DC) is performed, will be described with reference to FIGS. 6 to 8.

Figures 6 and 7 show 5G RAN20A and 6G RAN20B in which UE200 executes DC, and CN30 (5GC30A and 6GC30B) connected to each RAN. Figure 6 shows an example in which an interface (IF) capable of communicating information such as settings for UE200 is provided between 5G RAN20A and 6G RAN20B. Figure 7 shows an example in which an IF like that in Figure 6 is not provided between 5G RAN20A and 6G RAN20B, and instead 5GC30A and 6GC30B are connected. Note that in the example shown in Figure 6, the CN30 may be only one of 5GC30A or 6GC30B.

Figure 8 shows an example of the protocol stack of UE200 in Figure 7 that executes DC for 5G RAN20A and 6G RAN20B. UE200 can be equipped with separate protocol stacks for 5G RAN and 6G RAN. Such protocol stacks are called dual stacks. UE200 that supports dual stacks can also cancel DC and communicate only with 5G RAN20A, for example, by transitioning from dual stack mode to single stack mode. DC for different RATs (specifically, base stations belonging to different RATs) is specifically called Multi-Radio DC (MR-DC).

The protocol stack may include, for example, a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a radio resource control (RRC) layer. Furthermore, the protocol stack may include a non-access layer (NAS) that enables connection to a core network (CN).

When UE200 is equipped with a NAS as shown in FIG. 8, it can make a registration request to at least one of 5GC30A or 6GC30B. UE200 may be registered with only one of 5GC30A or 6GC30B, or may be registered with both 5GC30A and 6GC30B. The latter registration may be called dual registration.

(4) Operation of Wireless Communication System (4.1) Issues Depending on the network architecture, there may be no direct interface between a 5G node and a 6G node, or even if an interface is provided, it may be unavailable. For this reason, the 6G node may not be able to recognize that the UE is connected to both a 6G cell and a 5G cell. In this case, the 6G node may request an inter-RAT HO to the 5G cell to which the UE is currently connected, for example, via the core network (CN). Such an HO request is not only ineffective but also wastes resources because it involves many processes compared to cell release.

For example, as shown in Figure 9, consider a case where UE200, which executes MR-DC for 5G node 100A and 6G node 100B, moves in the direction of the arrow, causing the quality of the 6G cell provided by 6G node 100B to deteriorate. In this case, if 6G node 100B can recognize that UE200 is connected to not only a 6G cell but also a 5G cell, it is most reasonable for it to instruct UE200 to release the 6G cell.

Furthermore, as shown in Figure 10, consider the case where UE200 executing MR-DC for 5G node 100A and 6G node 100B moves in the direction of the arrow, causing a deterioration in the quality of the 5G cell provided by 5G node 100A (5G cell A in the figure) and the quality of the 6G cell provided by 6G node 100B. In this case too, if 6G node 100B can recognize that UE200 is connected to not only a 6G cell but also a 5G cell, it is most reasonable for it to instruct UE200 to release the 6G cell. In this case, 5G node 100A instructs UE200 to perform intra-RAT HO (HO from 5G cell A to 5G cell B in the figure).

On the other hand, consider the case where UE200, which is connected only to 6G node 100B, moves in the direction of the arrow, as shown in Figure 11, causing the quality of the 6G cell provided by 6G node 100B to deteriorate. In this case, if 6G node 100B can recognize that UE200 is operating in single stack mode, it is reasonable for it to instruct UE200 to perform an inter-RAT HO to its destination 5G node 100A.

Furthermore, if UE200 moves to a 6G cell, an inter-frequency measurement configured for UE200 by 5G node 100A may be configured as an intra-frequency measurement by 6G node 100B. In this way, duplication of settings related to Radio Resource Management (RRM) measurements should be avoided.

(4.2) Operational Examples Specific operational examples will be described below with reference to Figures 12 to 18. In this specification, the gNB100A (5G node 100A) may be replaced with the 5G RAN20A, and the gNB100B (6G node 100B) may be replaced with the 6G RAN20B. Conversely, the 5G RAN20A may be replaced with the gNB100A (5G node 100A) constituting the 5G RAN20A, and the 6G RAN20B may be replaced with the gNB100B (6G node 100B) constituting the 6G RAN20B.

As shown in Figure 12, as UE200 moves, it reports to the connected 6G node 100B that the quality of the 6G cell provided by 6G node 100B has deteriorated (this corresponds to "measurement report" in the figure). At this time, for the reasons mentioned above, 6G node 100B may not be able to determine whether UE200 is connected only to a 6G cell, or whether it is also connected to a 5G cell provided by 5G node 100A. To solve this problem, UE200 notifies the connected 6G node 100B of the stack mode in which it is operating (this corresponds to "stack mode" in the figure). That is, if UE200 is connected to not only a 6G cell but also a 5G cell, it notifies "dual stack mode," and if it is connected to only a 6G cell, it notifies "single stack mode." Note that the notification of the stack mode may also be made to 5G node 100A.

This allows the 6G node 100B to issue instructions according to the connection status of the UE200 (corresponding to the indication in the figure). Specifically, if the 6G node 100B is notified by the UE200 that it is operating in dual stack mode, it instructs the 6G node 100B to release the 6G cell. In other words, the 6G node 100B does not trigger an inter-RAT HO to the 5G cell (does not configure inter-RAT measurements for the UE200). Note that the notification of dual stack mode may indicate a dual stack with the same operator, or may indicate a dual stack with different operators. If the notification of dual stack mode indicates a dual stack with different operators, the 6G node 100B may trigger an inter-RAT HO to the 5G cell.

On the other hand, when the 6G node 100B is notified by the UE 200 that it is operating in single stack mode, it instructs the 6G node 100B to perform inter-RAT HO to the 5G cell. Specifically, the 6G node 100B instructs the 5G node 100B to measure the reception quality of the 5G cell provided by the 5G node.

Note that the UE 200 may notify the 6G node 100B (or the 5G node 100A) that such inter-RAT HO will not be performed (inter-RAT measurements will not be performed).

FIG. 13 also shows the sequence in which UE200 is instructed by 5G node 100A to perform intra-RAT HO when operating in dual stack mode. First, UE200 is instructed by 5G node 100A to measure neighboring cells of the 5G cell to which UE200 is connected (corresponding to indication in the figure). UE200 measures neighboring cells provided by 5G node 100A and notifies 5G node 100A of the measurement results. At this time, UE200 may report the measurement results to 6G node 100B (corresponding to measurement report in the figure).

In response to this, the 5G node 100A instructs the UE200 to perform HO to the adjacent cell (corresponding to the HO indication in the figure). Note that the HO indication may be interpreted as an HO command or a cell switch command, and may include the cell ID of the target cell for which the UE200 is to perform HO. This causes the UE200 to perform intra-RAT HO. The UE200 may also report to the 6G node 100B that it has received an instruction from the 5G node 100A to perform HO to the adjacent cell (corresponding to the HO report in the figure).

Note that the measurement report in FIG. 13 may include, for example, information indicating the neighboring cell with the best reception quality. In this case, the information indicating the neighboring cell with the best reception quality may be the cell ID of the cell in question, or the measured reception quality (for example, Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), Signal to Interference plus Noise Ratio (SINR)).

Furthermore, UE200 may report to 6G node 100B information (e.g., cell ID) of cells in the RRC connected state among the cells provided by 5G node 100A and information (e.g., cell ID) of cells in the RRC IDLE camp state. UE200 may also report to 6G node 100B the settings (e.g., measObject (frequency), event, measId) related to each of intra-frequency measurements, inter-frequency measurements, and RAT measurements set by 5G node 100A.

Furthermore, a cooperative node 500 may be provided between the 5G node 100A and the 6G node 100B. The cooperative node 500 may determine settings for intra-frequency measurements, inter-frequency measurements, and RAT measurements in the 5G RAT 20A and the 6G RAT 20B, and set these settings in the 5G node 100A and the 6G node 100B.

When a cooperative node 500 is provided, as shown in FIG. 14, the UE 200 transmits a measurement report to the 5G node 100A regarding the 5G cell provided by the 5G node 100A, and transmits a measurement report to the 6G node 100B regarding the 6G cell provided by the 6G node 100B. The 5G node 100A and the 6G node 100B transmit the measurement report received from the UE 200 to the cooperative node 500.

As a result, the cooperative node 500 can determine whether or not the UE200 will perform HO, which cell to perform HO to if HO is to be performed, which cell to have the UE200 release (RRC release), and instructions to the UE200 to switch stack modes (for example, an instruction to switch from dual stack mode to single stack mode, an instruction to the RAT to stop communication). Note that this instruction may be transmitted to the UE200 via at least one of the 5G node 100A and the 6G node 100B.

As described above, the UE200 in this embodiment can notify the 6G node 100B of its stack mode. This allows the 6G node 100B to appropriately instruct the UE200 to release the cell or perform inter-RAT HO.

(4.3) Cooperative Node A cooperative node 500 applicable to the above-described operation example will be described with reference to Figs. 15 to 17. As shown in Fig. 15, the cooperative node 500 is provided to exchange information mainly to be set in the UE 200 between the 5G node 100A and the 6G node 100B. The cooperative node 500 may be provided in the OAM, or may be provided in the CN 30 (e.g., 6GC 30B) as shown in Fig. 16. In this case, the cooperative node 500 may be called a mobility manager 500.

FIG. 17 shows a modified example of FIG. 16. Specifically, it shows a case where the 6G node 100B is separated into a CU and a DU, and the CU is provided in the 6GC 30B rather than the 6G RAN 20B. In this case, the cooperative node 500 may be considered to be included in the 6G node 100B or in the 6GC 30B.

(5) Other Embodiments The contents of the present invention have been described above in accordance with the embodiments, but 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.

In the above-described embodiment, the first radio base station is the 5G node 100A and the second radio base station is the 6G node 100B, but the first radio base station may be the 6G node 100B and the second radio base station may be the 5G node 100A. In other words, the above-described embodiment may be applied by replacing the 5G node 100A and the 6G node 100B with each other.

The network architecture of the above-described embodiment may include 4G RAN20C and 4GC30C, as shown in Figures 18 and 19. In this case, UE200 may be connected to any two RANs simultaneously, or may be connected to three RANs simultaneously. In the case of Figure 18, as in the case of Figure 6, it is sufficient to have any one CN30. In addition, in the case of Figure 18, any two CN30s may also be present.

The above operational examples may be combined and applied in a complex manner, provided no contradictions arise.

Note that the block diagrams used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of hardware and/or software. Furthermore, there are no particular limitations on how each functional block is realized. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are connected directly or indirectly (for example, using wires, wirelessly, etc.) and these multiple devices. A functional block may also be realized by combining software with the single device or multiple devices.

Functions include, but are not limited to, judgment, determination, assessment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, selection, establishment, comparison, assumption, expectation, regard, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, and assignment. For example, a functional block (component) that performs transmission functions is called a transmitting unit or transmitter. As mentioned above, there are no particular limitations on how these functions are implemented.

For example, the base station 100, terminal 200, etc. in one embodiment of the present disclosure may function as a computer that performs processing of the wireless communication method of the present disclosure. Figure 20 is a diagram showing an example of the hardware configuration of the base station 100 and terminal 200 in one embodiment of the present disclosure. The above-mentioned base station 100 and terminal 200 may be physically configured as a computer device including a processor 1001, memory 1002, storage 1003, communication device 1004, input device 1005, output device 1006, bus 1007, etc.

In the following explanation, the term "apparatus" can be interpreted as circuit, device, unit, etc. The hardware configuration of the base station 100 and terminal 200 may be configured to include one or more of the devices shown in the figure, or may be configured to exclude some of the devices.

The functions of the base station 100 and terminal 200 are realized by loading specific software (programs) onto hardware such as the processor 1001 and memory 1002, causing the processor 1001 to perform calculations, control communications by the communication device 1004, and control at least one of reading and writing data from and to the memory 1002 and storage 1003.

The processor 1001, for example, runs an operating system to control the entire computer. The processor 1001 may be configured as a central processing unit (CPU) that includes an interface with peripheral devices, a control unit, an arithmetic unit, registers, etc.

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 in accordance with these. The programs used are those that cause a computer to execute at least some of the operations described in the above-mentioned embodiments. Furthermore, while the above-mentioned various processes have been described as being executed by a single processor 1001, they may also be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The programs may also be transmitted from a network via telecommunications lines.

Memory 1002 is a computer-readable recording medium and may be composed of, for example, at least one of 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 (primary storage device), etc. Memory 1002 can store executable programs (program code), software modules, etc. for implementing a wireless communication method according to one embodiment of the present disclosure.

Storage 1003 is a computer-readable recording medium, and may be composed of at least one of, for example, an optical disk such as a Compact Disc ROM (CD-ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray (registered trademark) disc), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy (registered trademark) disk, a magnetic strip, etc. Storage 1003 may also be referred to as an auxiliary storage device. The above-mentioned storage medium may be, for example, a database, a server, or other suitable medium including at least one of memory 1002 and storage 1003.

The communication device 1004 is hardware (transmission/reception device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as, for example, a network device, network controller, network card, or communication module. The communication device 1004 may be configured to include a high-frequency switch, duplexer, filter, frequency synthesizer, etc. to realize at least one of frequency division duplex (FDD) and time division duplex (TDD).

The input device 1005 is an input device (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.) that accepts input from the outside. The output device 1006 is an output device (e.g., a display, speaker, LED lamp, etc.) that outputs to the outside. Note that the input device 1005 and the output device 1006 may be integrated into one device (e.g., a touch panel).

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

Furthermore, the base station 100 and the terminal 200 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA), and some or all of the functional blocks may be realized by this hardware. For example, the processor 1001 may be implemented using at least one of these pieces of hardware.

The notification of information is not limited to the aspects/embodiments described in this disclosure and may be performed using other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), higher layer signaling (e.g., Radio Resource Control (RRC) signaling, Medium Access Control (MAC) signaling), broadcast information (Master Information Block (MIB), System Information Block (SIB)), other signals, or a combination of these. Furthermore, RRC signaling may be referred to as an RRC message, and may be, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, etc.

Each aspect/embodiment described in this disclosure may be used in conjunction with 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 Acc The specification may apply to at least one of systems using 802.11 (Wi-Fi), 802.16 (WiMAX), 802.20, Ultra-WideBand (UWB), Bluetooth, or other appropriate systems, and next-generation systems that are extended, modified, created, or defined based on these. It may also apply to a combination of multiple systems (for example, a combination of LTE and/or LTE-A with 5G).

The order of the processing steps, sequences, flowcharts, etc. of each aspect/embodiment described in this disclosure may be changed unless inconsistent. For example, the methods described in this disclosure present elements of various steps using an example order, and are not limited to the particular order presented.

In this disclosure, certain operations that are described 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 that have base stations, it is clear that various operations performed for communication with terminals may be performed by at least one of the base station and other network nodes other than the base station (such as, but not limited to, an MME or S-GW). While the above example shows a case where there is one other network node other than the base station, it may also be a combination of multiple other network nodes (for example, an MME and an S-GW).

Information, signals (information, etc.) can be output from a higher layer (or lower layer) to a lower layer (or higher layer). They may also be input and output via multiple network nodes.

Input and output information may be stored in a specific location (for example, memory) or managed using a management table. Input and output information may be overwritten, updated, or added to. Output information may be deleted. Input information may be sent to another device.

The determination may be made based on a value represented by one bit (0 or 1), a Boolean value (true or false), or a numerical comparison (for example, comparison with a predetermined value).

Each aspect/embodiment described in this disclosure may be used alone, in combination, or switched between depending on the implementation. Furthermore, notification of specified information (e.g., notification that "X is true") is not limited to being done explicitly, but may also be done implicitly (e.g., not notifying the specified information).

Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Software, instructions, information, etc. may also be transmitted and received via a transmission medium. For example, if software is transmitted from a website, server, or other remote source using wired technology (such as coaxial cable, fiber optic cable, twisted pair, or Digital Subscriber Line (DSL)) and/or wireless technology (such as infrared or microwave), then the wired and/or wireless technology is included within the definition of transmission medium.

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

Note that terms explained 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 a channel and a symbol may be a signal (signaling). Furthermore, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, etc.

As used in this disclosure, the terms "system" and "network" are used interchangeably.

Furthermore, the information, parameters, etc. described in this disclosure may be expressed using absolute values, relative values from a predetermined value, or other corresponding information. For example, radio resources may be indicated by an index.

The names used for the parameters described above are not intended to be limiting in any way. Furthermore, the mathematical formulas using these parameters may differ from those explicitly disclosed in this disclosure. The various channels (e.g., PUCCH, PDCCH, etc.) and information elements may be identified by any suitable names, and therefore the various names assigned to these various channels and information elements are not intended to be limiting in any way.

In this disclosure, terms such as "base station (BS)," "radio 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.

A base station can accommodate one or more (e.g., three) cells (also called sectors). When a base station accommodates multiple cells, the entire coverage area of the base station can be divided into multiple smaller areas, and each smaller area can also provide communication services by a base station subsystem (e.g., a small indoor base station (Remote Radio Head, RRH)). The terms "cell" or "sector" refer to part or the entire coverage area of at least one of the base station and base station subsystems that provide communication services within this coverage area.

In this disclosure, a base station transmitting information to a terminal may be interpreted as the base station instructing the terminal to control or operate based on the information.

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

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 some other suitable terminology.

At least one of the base station and the mobile station may be referred to as 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 moving object, the moving object itself, etc. The moving object is a movable object, and may move at any speed. Naturally, this also includes cases where the moving object is stationary. Examples of the moving object include, but are not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcars, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones (registered trademark), multicopters, quadcopters, balloons, and objects mounted thereon. The moving object may also be a moving object that moves autonomously based on an operation command. It may be a vehicle (e.g., a car, an airplane, etc.), an unmanned moving object (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 operations. 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.

Furthermore, the term "base station" in the present disclosure may be read as "terminal." For example, the aspects/embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a terminal is replaced with communication between multiple terminals (which may be called, for example, Device-to-Device (D2D) or Vehicle-to-Everything (V2X)). In this case, the terminal 200 may be configured to have the functions possessed by the base station 100 described above. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to communication between terminals (for example, "side"). For example, terms such as "uplink channel" and "downlink channel" may be read as "side channel."

Similarly, the term "terminal" in this disclosure may be interpreted as "base station." In this case, the base station 100 may be configured to have the functions of the terminal 200 described above.

FIG. 21 shows an example configuration of a vehicle 2001. As shown in FIG. 21, the vehicle 2001 is equipped with 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 2021-2029, an information service unit 2012, and a communication module 2013.

The drive unit 2002 may be composed of, for example, an engine, a motor, or a hybrid of an engine and a motor.

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 rear wheels based on the operation of the steering wheel operated by the user.

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

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

Information service unit 2012 is composed of various devices, such as a car navigation system, audio system, speakers, television, and radio, that provide (output) various types of information, including driving information, traffic information, and entertainment information, as well as one or more ECUs that control these devices. Information service unit 2012 uses information obtained from external devices via communication module 2013, etc., to provide various types of multimedia information and multimedia services to the occupants of vehicle 2001.

The information service unit 2012 may include input devices (e.g., keyboards, mice, microphones, switches, buttons, sensors, touch panels, etc.) that accept input from the outside, and may also include output devices (e.g., displays, speakers, LED lamps, touch panels, etc.) that output to the outside.

The driving assistance system unit 2030 is composed of various devices that provide functions to prevent accidents and reduce the driver's driving burden, such as millimeter-wave radar, Light Detection and Ranging (LiDAR), cameras, positioning locators (e.g., GNSS, etc.), map information (e.g., high-definition (HD) maps, autonomous vehicle (AV) maps, etc.), gyro systems (e.g., inertial measurement units (IMUs), inertial navigation systems (INSs), etc.), artificial intelligence (AI) chips, and AI processors, as well as one or more ECUs that control these devices. The driving assistance system unit 2030 also transmits and receives various information via the communication module 2013 to realize driving assistance functions or autonomous driving functions.

The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 2001 via the communication port. For example, the communication module 2013 transmits and receives data via the communication port 2033 to and from 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, microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021-2029, all of which are provided on the vehicle 2001.

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 transmits and receives various 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, a mobile station, etc.

The communications module 2013 may transmit, via wireless communication, to an external device at least one of the signals from the various sensors 2021-2029 described above that are input to the electronic control unit 2010, information obtained based on the signals, and information based on input from the outside (user) obtained via the information service unit 2012. The electronic control unit 2010, the various sensors 2021-2029, the information service unit 2012, etc. may also be referred to as input units that accept input. For example, the PUSCH transmitted by the communications module 2013 may include information based on the above input.

The communication module 2013 receives various information (traffic information, traffic signal information, vehicle distance information, etc.) transmitted from external devices and displays it on the information service unit 2012 provided in the vehicle. The information service unit 2012 may also be called an output unit that outputs information (for example, outputs information to a device such as a display or speaker based on the PDSCH received by the communication module 2013 (or data/information decoded from the PDSCH)).

Furthermore, the communication module 2013 stores various information received from external devices in memory 2032 that can be used by 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, axle 2009, sensors 2021-2029, and the like provided on the vehicle 2001.

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, inquiring (e.g., searching a table, database, or other data structure), and ascertaining, all of which are considered to be "judging" or "determining." "Determining" may also include receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, and accessing (e.g., accessing data in memory), all of which are considered to be "judging" or "determining." "Determining" may also include resolving, selecting, choosing, establishing, comparing, and other actions, all of which are considered to be "judging" or "determining." In other words, "judgment" and "decision" can include regarding some action as having been "judged" or "decided." Furthermore, "judgment (decision)" can also be interpreted as "assuming," "expecting," "considering," etc.

The terms "connected," "coupled," or any variation thereof, refer to 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" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access." As used in this disclosure, two elements may be considered to be "connected" or "coupled" to each other using at least one of one or more wires, cables, and printed electrical connections, as well as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and optical (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

The reference signal may also be abbreviated as RS, or may be called a pilot depending on the applicable standard.

As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed or that the first element must in some way precede the second element.

The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

When the terms "include," "including," and variations thereof are used in this disclosure, these terms are intended to be inclusive, similar to the term "comprising." Furthermore, when the term "or" is used in this disclosure, it is not intended to be an exclusive or.

A radio frame may be composed of one or more frames in the time domain. Each of the one or more frames in the time domain may be called a subframe. A subframe may further be composed 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.

Numerology may be a communication parameter that applies to at least one of the transmission and reception of a signal or channel. Numerology may indicate, 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 structure, specific filtering operations performed by the transmitter and receiver in the frequency domain, and specific windowing operations performed by the transmitter and receiver in the time domain.

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 numerology-based time unit.

A slot may include multiple minislots. Each minislot may consist of one or more symbols in the time domain. A minislot may also be called a subslot. A minislot may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called PDSCH (or PUSCH) mapping type B.

Radio frame, subframe, slot, minislot, and symbol all represent time units for transmitting signals. Other names corresponding to radio frame, subframe, slot, minislot, and symbol may also be used.

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 the subframe and the TTI may be a subframe (1 ms) as in existing LTE, a period shorter than 1 ms (e.g., 1 to 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.

Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, a base station performs scheduling to allocate radio resources (such as the frequency bandwidth and transmission power that can be used by each terminal) to each terminal in TTI units. However, the definition of TTI is not limited to this.

The TTI may be a transmission time unit for a channel-encoded data packet (transport block), code block, code word, etc., or it may be a processing unit for scheduling, link adaptation, etc. When a TTI is given, the time interval (e.g., number of symbols) to which the transport block, code block, code word, etc. is actually mapped may be shorter than the TTI.

Note that when one slot or one minislot is called a TTI, one or more TTIs (i.e., one or more slots or one or more minislots) may be the smallest time unit for scheduling. Furthermore, the number of slots (minislots) that make up the smallest time unit for scheduling may be controlled.

A TTI with a time length of 1 ms may be referred to as a regular TTI (TTI in LTE Rel. 8 to 12), normal TTI, long TTI, regular subframe, normal subframe, long subframe, slot, etc. A TTI shorter than a regular TTI may be referred to as a shortened TTI, short TTI, partial TTI (partial or fractional TTI), shortened subframe, short subframe, minislot, subslot, slot, etc.

Note that a long TTI (e.g., a normal TTI, subframe, etc.) may be interpreted as a TTI having a time length of more than 1 ms, and a short TTI (e.g., a shortened TTI, etc.) may be interpreted as a TTI having a TTI length of 1 ms or more but less than the TTI length of a long TTI.

A resource block (RB) is a resource allocation unit in the time domain and frequency domain, and may include one or more consecutive subcarriers in the frequency domain. The number of subcarriers included in an RB may be the same regardless of numerology, and may be, for example, 12. The number of subcarriers included in an RB may also be determined based on numerology.

Furthermore, the time domain of an RB may include one or more symbols and may be one slot, one minislot, one subframe, or one TTI in length. One TTI, one subframe, etc. may each be composed of one or more resource blocks.

Note that one or more RBs may also be referred to as a physical resource block (PRB), sub-carrier group (SCG), resource element group (REG), PRB pair, RB pair, etc.

Furthermore, a resource block may be composed of one or more resource elements (REs). For example, one RE may be a radio resource region of one subcarrier and one symbol.
A Bandwidth Part (BWP) (which may also be referred to as a fractional bandwidth) may represent a subset of contiguous common resource blocks (RBs) for a given numerology on a given carrier, where the common RBs may be identified by their index relative to a common reference point of the carrier. PRBs may be defined in a given BWP and numbered within that BWP.

BWPs may include a BWP for UL (UL BWP) and a BWP for DL (DL BWP). One or more BWPs may be configured for a UE within one carrier.

At least one of the configured BWPs may be active, and the UE may not expect to transmit or receive a specific signal/channel outside of the active BWP. Note that "cell," "carrier," etc. in this disclosure may be read as "BWP."

The structures of the radio frames, subframes, slots, minislots, and symbols described above are merely examples. For example, the number of subframes included in a radio frame, the number of slots per subframe or radio 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, as well as the number of symbols within a TTI, the symbol length, and the cyclic prefix (CP) length can be changed in various ways.

"Maximum transmit power" as used in this disclosure may mean the maximum value of transmit power, the nominal UE maximum transmit power, or the rated UE maximum transmit power.

In this disclosure, where articles are added by translation, such as a, an, and the in English, this disclosure may include the noun following these articles being plural.

In this disclosure, the term "A and B are different" may mean "A and B are different from each other." It should be noted that the term may also mean "A and B are each different from C." Terms such as "separate" and "combined" may also be interpreted in the same way as "different."

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 spirit and scope of the present disclosure, which are defined by the claims. Therefore, the description of the present disclosure is intended for illustrative purposes only and does not have any limiting meaning on the present disclosure.

(Additional Note)
The above disclosure may be expressed as follows:

The first feature is a terminal equipped with a control unit that switches between a first mode that enables simultaneous connection to a first cell provided by a first radio base station and a second cell provided by a second radio base station, and a second mode that connects only to the second cell, and a transmission unit that transmits first mode information to the second radio base station when the control unit is operating in the first mode, and transmits second mode information to the second radio base station when the control unit is operating in the second mode.

A second feature is the terminal of the first feature, further comprising a receiving unit that receives an instruction to release the second cell from the second radio base station that has received the first mode information.

A third feature is the terminal of the first feature, further comprising a receiving unit that receives an instruction to measure the reception quality of the first cell from the second radio base station that has received the second mode information.

A fourth feature is the terminal according to the second feature, wherein the control unit operates in the first mode, the receiving unit receives an instruction from the first radio base station to measure the reception quality of a neighboring cell that is adjacent to the first cell and is served by the first radio base station, and the transmitting unit transmits the measurement results of the neighboring cell to the first radio base station and the second radio base station.

A fifth feature is the terminal of the fourth feature, wherein the receiver receives a handover instruction to the neighboring cell from the first radio base station, and the transmitter reports to the second radio base station that the handover instruction has been received.

A sixth feature is a base station comprising: a receiver that receives first mode information from a terminal when the terminal is operating in a first mode that enables simultaneous connection to a first cell provided by another base station and a second cell provided by the base station; and receives second mode information when the terminal is operating in a second mode that connects only to the second cell; and a transmitter that transmits to the terminal an instruction to release the second cell based on the first mode information, and an instruction to measure the reception quality of the first cell based on the second mode information.

10 Wireless Communication System 20 RAN
20A 5G RAN
20B 6G RAN
20C 4G RAN
30CN
30A 5GC
30B 6GC
30C 4GC
100 Base station 100A 5G node 100B 6G node 110 Radio signal transmitting/receiving unit 120 Control unit 200 Terminal 210 Radio 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 300 AMF
400 NWDAF
500 Collaborative node 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 Left and right front wheels 2008 Left and right rear wheels 2009 Axle 2010 Electronic control unit 2012 Information service unit 2013 Communication module 2021 Current sensor 2022 RPM 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 section 2031 Microprocessor 2032 Memory (ROM, RAM)
2033 communication port (IO port)

Claims (6)

a control unit that switches between a first mode that enables simultaneous connection to a first cell provided by a first radio base station and a second cell provided by a second radio base station and a second mode that connects only to the second cell;
a transmitter that transmits first mode information to the second radio base station when the controller is operating in the first mode, and transmits second mode information to the second radio base station when the controller is operating in the second mode;
A terminal comprising: a receiving unit that receives an instruction to release the second cell from the second radio base station that has received the first mode information,
The terminal according to claim 1 . a receiving unit that receives, from the second radio base station that has received the second mode information, an instruction to measure the reception quality of the first cell,
The terminal according to claim 1 . the control unit operates in the first mode,
the receiving unit receives, from the first radio base station, an instruction to measure reception quality of a neighboring cell that is adjacent to the first cell and is served by the first radio base station;
the transmitter transmits the measurement results of the neighboring cells to the first radio base station and the second radio base station.
The terminal according to claim 2. the receiving unit receives a handover instruction to the neighboring cell from the first radio base station;
the transmitter reports to the second radio base station that the handover command has been received.
The terminal according to claim 4. A base station,
a receiving unit that receives first mode information from a terminal when the terminal is operating in a first mode that enables simultaneous connection to a first cell provided by another base station and a second cell provided by the base station, and receives second mode information when the terminal is operating in a second mode that connects only to the second cell;
a transmitter that transmits, to the terminal, an instruction to release the second cell based on the first mode information, and an instruction to measure reception quality of the first cell based on the second mode information;
A base station comprising: