Radio base station and radio communication method

Abstract

This radio base station operates according to a second radio access technology different from a first radio access technology, and executes a transition of the terminal from a transition source radio base station according to the first radio access technology. The radio base station: receives, from the transition source radio base station, a transition request for requesting transition by means of an interface with the transition source radio base station; and transmits, to the transition source radio base station, a response to the transition request by means of the interface.

Description

Wireless Base Station and Wireless Communication Method

[0001] The present disclosure relates to a wireless base station and a wireless communication method that support the transition of a terminal between radio access technologies (RATs).

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

[0003] In 5G, network functions (NFs) that make up the core network (5GC) are defined (Non-Patent Document 1). A radio access network node (5G RAN node) such as a wireless base station (gNB) and the 5GC are connected by an interface called NG (Non-Patent Document 2).

[0004] 3GPP TS 23.501 V18.8.0, 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; System architecture for the 5G System (5GS); Stage 2 (Release 18), 3GPP, December 2024 3GPP TS 38.413 V18.4.0, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; NG Application Protocol (NGAP) (Release 18), 3GPP, December 2024

[0005] The 6G core network (6GC) may be implemented as an extension of the existing 5GC (which may also be called e5GC). In this case, the transition of user equipment (UE) between 5G and 6G, specifically handover (Inter-RAT HO) or LTM (Lower layer Triggered Mobility), could be done via an interface connecting the 5G RAN node and the 6G RAN node (e.g., an Xn interface), rather than via the NG interface connecting the RAN node and the CN, from the perspective of load balancing between the RAN and the core network (CN).

[0006] However, applying the existing UE transition procedure between RATs via CN to UE transitions between RAN nodes via such interfaces presents a problem: it is not possible to achieve normal operation.

[0007] Therefore, the following disclosure is made in view of these circumstances and aims to provide a wireless base station and wireless communication method that can achieve normal and accurate transitions between UEs and RATs via an interface connecting RAN nodes.

[0008] One aspect of the present disclosure is a radio base station (gNB100) comprising: a control unit (control unit 140) that operates according to a second radio access technology different from a first radio access technology and executes terminal transitions from a source radio base station according to the first radio access technology; a receiving unit (message processing unit 130) that receives a transition request requesting the transition from the source radio base station via an interface with the source radio base station; and a transmitting unit (message processing unit 130) that transmits a response to the transition request to the source radio base station via the interface.

[0009] Figure 1 is an overall schematic diagram of the wireless communication system 10. Figure 2 is a diagram showing an example of the connection configuration between 6GC35 and gNB100. Figure 3 is a functional block diagram of gNB100. Figure 4 is a diagram showing an example of the UE200 handover procedure between a 5G RAN node and a 6G RAN node. Figure 5 is a diagram showing an example of the UE200 LTM procedure between a 5G RAN node and a 6G RAN node. Figure 6 is a diagram showing an example of the hardware configuration of gNB100 and UE200. Figure 7 is a diagram showing an example of the configuration of vehicle 2001.

[0010] 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.

[0011] (1) Overall schematic diagram 1 of the wireless communication system is an overall schematic diagram of the wireless communication system 10 according to this embodiment. In this embodiment, the wireless communication system 10 is a wireless communication system in accordance with 5G New Radio (NR) and 6G, and includes a 5G Radio Access Network 20 (hereinafter, 5GRAN20), a 6G Radio Access Network 30 (hereinafter, 6GRAN30), and a terminal 200 (User Equipment 200, hereinafter, UE200).

[0012] The wireless communication system 10 may include a wireless communication system that conforms to a method called Long Term Evolution (LTE) or 4G. In other words, the wireless communication system 10 may be composed of wireless communication systems that conform to multiple different radio access technologies (RATs). Furthermore, the wireless communication system 10 may support functions related to the Industrial Internet of Things (IIoT) and URLLC (Ultra-Reliable and Low Latency Communications). In this embodiment, 5G (NR) may be called the first radio access technology, and 6G may be called the second radio access technology, which is different from the first radio access technology. Alternatively, 6G may be called the first radio access technology, and 5G may be called the second radio access technology.

[0013] 5GRAN20 and 6GRAN30 include a radio base station 100 (hereinafter referred to as gNB100). The specific configuration of the wireless communication system 10, including the number of gNBs (or eNBs, etc.) and UEs, is not limited to the example shown in Figure 1. Furthermore, 5GRAN20 and / or 6GRAN30 may be connected to a server managed by a 3GPP service provider or a server managed by a party other than the said service provider (3GPP or non-3GPP server).

[0014] 5GRAN20 includes multiple 5G RAN Nodes (Radio Access Network Nodes), specifically gNBs (or ng-eNBs). Similarly, 6GRAN30 includes multiple 6G RAN Nodes (Radio Access Network Nodes), specifically gNBs. 5GRAN20 and 6GRAN30 are connected to 6GC35, which is a 6G-compliant core network.

[0015] 6GC35 may be interpreted as a core network (CN) conforming to the 6G specification. In this embodiment, 6GC35 may be configured by extending a CN (5GC) conforming to the 5G specification. For this reason, 6GC35 may be called e5GC (enhanced 5GC or evolved 5GC). Since 6GC35 combines the functions of both 5GC and 6GC, as described above, both 5GRAN20 and 6GRAN30 may be connected to 6GC35.

[0016] 6GC35, like the existing 5GC, may include logical nodes (network devices) that provide network functions (NF). Specifically, the NF may include an Access and Mobility Management Function (AMF) that provides access and mobility management functions for the UE200, a Session Management Function (SMF) that provides session management functions, and a Location Management Function (LMF) that is responsible for communication control related to location information services defined in 6GC35. In addition, a UDM / UDR (Unified Data Management / User Data Repository) may be connected to the AMF and / or SMF. Note that 5GRAN20, 6GRAN30, and 6GC35 may simply be referred to as "network".

[0017] As mentioned above, 6GC35 may be implemented as an extension of 5GC, but it may also include new network functions (NFs) that are not present in 5GC. For example, 6GC35 may include NFs that handle processing related to artificial intelligence / machine learning models (AI / ML Models) and processing related to network energy consumption.

[0018] The gNB100 that constitutes 5GRAN20 is a 5G (NR) compliant radio base station and performs NR-compliant wireless communication with the UE200. The gNB100 that constitutes 6GRAN30 is a 6G compliant radio base station and performs 6G-compliant wireless communication with the UE200.

[0019] Figure 2 shows an example of a connection configuration between 6GC35 and gNB100. As shown in Figure 2, gNB100 may consist of a CU (Central Unit), a DU (Distributed Unit), and an RU (Remote Unit). The DU may be located separately from the CU at a geographically different location. The RU may also be located separately from the DU (and CU) at a geographically different location.

[0020] One or more DUs may be connected to a CU. Furthermore, gNB100 (gNB-CU, gNB-DU) may be connected via an Xn interface, and CU and DU may be connected via an F1 interface. gNB100 (CU) and the nodes (functions) constituting 6GC35 may be connected via an NG interface (which may be called by a different name). Note that 6GC35 and gNB100 (gNB-CU) constituting 6GRAN30 may be connected not by an NG, but by, for example, a newly defined interface. RU may perform tasks such as transmitting and receiving radio signals and converting between radio frequency (RF) and baseband signals.

[0021] The gNB100 and UE200 can support Massive MIMO (Multiple-Input Multiple-Output), which generates a more directional beam 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 between the UE and multiple NG-RAN Nodes. The UE200 may also perform handover (HO) to different RATs.

[0022] The UE200 may perform measurement reporting periodically. The UE200 may also perform measurement reporting for each event. Entering conditions to start measurement reporting and leaving conditions to end measurement reporting may be defined for each event. The entering conditions may be interpreted as the conditions for determining whether or not to include an event in the measurement report, and the leaving conditions may be interpreted as the conditions for determining whether or not to exclude an event from the measurement report.

[0023] Furthermore, in the wireless communication system 10, not only Layer 3 mobility control of the UE200 (which may also be called L3 Mobility) but also Layer 1 and / or Layer 2 mobility control (LTM: Lower Layer Triggered Mobility) may be applied. L3 Mobility may be interpreted as mobility control at the Radio Resource Control Layer (RRC). On the other hand, LTM may be interpreted as mobility control at the Physical Layer (PHY), Medium Access Control Layer (MAC), Radio Link Control Layer (RLC), and Packet Data Convergence Protocol Layer (PDCP).

[0024] In a broad sense, the mobility of the UE200 may refer to the ease of movement and maneuverability of the UE200, but in this embodiment, it may also refer to the minimization of call drop, radio link (including beam) failure, unnecessary handovers, ping-pong situations, etc.

[0025] In this embodiment, the channel includes a control channel and a data channel. The control channel includes PDCCH (Physical Downlink Control Channel), PUCCH (Physical Uplink Control Channel), PRACH (Physical Random Access Channel), and PBCH (Physical Broadcast Channel), among others.

[0026] Furthermore, data channels include PDSCH (Physical Downlink Shared Channel) and PUSCH (Physical Uplink Shared Channel), among others.

[0027] Reference signals include Demodulation Reference Signal (DMRS), Sounding Reference Signal (SRS), Phase Tracking Reference Signal (PTRS), and Channel State Information-Reference Signal (CSI-RS), while signals include channels and reference signals. Furthermore, "data" may refer to data transmitted via a data channel.

[0028] (2) Functional Block Configuration of the Wireless Communication System Next, the functional block configuration of the wireless communication system 10 will be described. Specifically, the functional block configuration of gNB100 will be described. Figure 3 is a diagram of the functional block configuration of gNB100. Note that Figure 3 shows only the main functional blocks related to the description of the embodiment, and gNB100 has other functional blocks (for example, a power supply unit). Also, Figure 3 shows the functional block configuration of gNB100, and for the hardware configuration, please refer to Figure 6.

[0029] As shown in Figure 3, the gNB100 comprises a wireless communication unit 110, a network IF unit 120, a message processing unit 130, and a control unit 140. The functions of the gNB100 constituting 6GRAN30 will be described below, but the gNB100 constituting 5GRAN20 may also have similar functions.

[0030] The wireless communication unit 110 transmits a downlink signal (DL signal) in accordance with 6G. The wireless communication unit 110 also receives an uplink signal (UL signal) in accordance with 6G.

[0031] The network interface unit 120 provides interfaces between RAN nodes and interfaces between RAN nodes and the core network, so-called network interfaces. For example, the network interface unit 120 may provide Xn interfaces between RAN nodes. Note that the Xn interface may be called by a different name. Furthermore, the Xn interface may connect gNB-CUs to each other or gNB-DUs to each other (see Figure 2).

[0032] Furthermore, the network interface unit 120 may provide an NG interface that connects the RAN node and the core network. The NG interface may be called by a different name. Also, as mentioned above, the gNB100 and 6GC35 that constitute 6GRAN30 may be connected by a new interface instead of an NG interface.

[0033] The message processing unit 130 performs processing related to the generation and transmission of various messages via the network interface (NG or Xn), as well as processing related to the reception and decoding of such messages.

[0034] In this embodiment, the message processing unit 130 may receive a transition request from the source radio base station (gNB100) of the UE200 via an interface with the source radio base station. In this embodiment, the message processing unit 130 may constitute a receiving unit. Herein, "transition" typically means handover (HO), but may also include LTM, or may be referred to by terms such as cell reselection.

[0035] Specifically, the message processing unit 130 may receive an HO request message from the source gNB (which may be a CU or a DU) via the Xn interface with the source gNB from which the UE200 transitioned. The message processing unit 130 may send an HO request Ackmessage, which is a response to the HO request message, to the source gNB (the source radio base station) via the Xn interface. In this embodiment, the message processing unit 130 may constitute a transmission unit.

[0036] In this example, the source gNB is gNB100 (5G RAN node) that constitutes 5GRAN20, and the destination (target) gNB is gNB100 (6G RAN node) that constitutes 6GRAN30. However, the source side may be a 6G RAN node and the target side may be a 5G RAN node.

[0037] Furthermore, in the case of LTM, LTM request message and LTM request ack message may be used instead of HO request message and HO request ack message.

[0038] The message processing unit 130 may receive a status transfer message from the source gNB via the Xn interface that transfers specific status information of the UE200. Specifically, the message processing unit 130 may receive an Early status transfer from the source gNB. The Early status transfer may be performed during the UE200 handover process to inform the target gNB of the UE200's status early. The Early status transfer may include the UE200's context (identification information, security-related information, etc.), the allocation status of radio resources, the quality of the radio link, etc.

[0039] Furthermore, the message processing unit 130 may receive a sequence number transfer message from the source gNB that transfers the status of the sequence number (SN) in the Packet Data Convergence Protocol Layer (PDCP). Specifically, the message processing unit 130 may receive an SN status transfer from the source gNB. The SN status transfer may include not only the SN in the PDCP, but also the frame number used to complement the SN counter, specifically the Hyper Frame Number (HFN), etc.

[0040] The message processing unit 130 may send timing-related information, including the Timing Advance (TA) for transmission by the UE200, to the source gNB via the Xn interface. Furthermore, after sending the timing-related information, the message processing unit 130 may receive a cell switching notification from the source gNB via the Xn interface.

[0041] Specifically, the message processing unit 130 may send a TA information notification to the source gNB that includes a TA value (timing adjustment value) applied to the uplink (UL) transmission by the UE200. The message processing unit 130 may also receive a Cell switch notification from the source gNB. The Cell switch notification may include identification information of the target cell (target cell ID) and the TCI (Transmission Configuration Indication) state ID, etc.

[0042] In addition to the TA value, the TA information notification may include the identification information of the candidate cell (candidate cell ID), the index of the random access (RA) preamble, the RA-RNTI (Radio Network Temporary Identifier), the identification information of the source DU (gNB-DU ID), and the Tag ID pointer indicating the ID corresponding to a specific tag. The TA information notification may be applied in LTM.

[0043] The message processing unit 130 may send a path switching request to the core network for the UE 200 and receive a response to the switching request from the core network. Specifically, the message processing unit 130 may send a Path switch request for requesting a path switch between the UE 200 and the RAN node to the 6GC 35. Also, the message processing unit 130 may receive a Path switch request Ack, which is a response to the Path switch request, from the 6GC 35.

[0044] The control unit 140 controls each functional block constituting the gNB 100. In the present embodiment, the control unit 140 may execute control regarding connection to the core network or another gNB (RAN node) via the network IF provided by the network IF unit 120.

[0045] Specifically, the control unit 140 may be connected to the 6GC 35 via the NG interface. Also, the control unit 140 may be connected to the gNB 100 constituting the 5G RAN 20 via the Xn interface. The control unit 140 may operate according to the 6G RAT as described above, but may be connected to the 6GC 35 via an interface (for example, the NG interface) commonly used for both the 5G RAT and the 6G RAT. That is, the same specification network IF may be used for the connection between the 5G RAN node and the 6G RAN node and the 6GC 35. However, such unification of the interface is not necessarily essential as described above.

[0046] Further, the control unit 140 may execute the transition of the UE 200 from the source gNB (RAN node) according to the 5G RAT. Specifically, the control unit 140 may execute a handover (HO) or LTM of the UE 200 from the 5G RAN node to the 6G RAN node. Also, the control unit 140 may execute a HO or LTM of the UE 200 from the 6G RAN node to the 5G RAN node.

[0047] (3) Operation of the wireless communication system Next, the operation of the wireless communication system 10 will be described. Specifically, the operation regarding the transition of the UE 200 between the 5G RAN node and the 6G RAN node will be described. As described above, the transition of the UE 200 may include a handover (HO) and LTM. Also, in the following operation example, HO (which may include LTM) between RANs may be realized via an Xn interface (which may be a provisional name) set between the 5G RAN node and the 6G RAN node.

[0048] It is difficult to directly apply the existing UE transition procedures between RATs to the transition of the UE between RATs via an interface connecting RAN nodes with different RATs. In the following, an operation example assuming that such an interface connecting RAN nodes is used will be described. Note that the technical problems to be achieved by the following operation example are not limited to such technical problems, and other technical problems not mentioned can be clearly understood by those having ordinary knowledge in the technical field from the description of the present embodiment.

[0049] FIG. 4 shows an example of the handover procedure of the UE 200 between the 5G RAN node and the 6G RAN node. Hereinafter, the parts different from the conventional handover procedure (see the underlined parts) will be mainly described.

[0050] As shown in Figure 4, the target gNB may receive an HO request message from the source gNB. After receiving the HO request message, the target gNB may send back an HO request Ackmessage to the source gNB, which is a response granting permission for the request.

[0051] The target gNB may receive an Early status transfer from the source gNB. The target gNB may also receive an SN status transfer from the source gNB. The target gNB may send a Handover success message to the source gNB indicating that the handover was successful. After sending the Handover success message, the target gNB may receive an SN status transfer from the source gNB.

[0052] Subsequently, the target gNB may send a Path switch request to 6GC (e5GC). The target gNB may receive a Path switch request Ack from 6GC, which is a response to the Path switch request.

[0053] Figure 5 shows an example of the UE200 LTM procedure between a 5G RAN node and a 6G RAN node. The following explanation will mainly focus on the differences from the handover procedure shown in Figure 4.

[0054] As shown in Figure 5, the target gNB may receive an LTM request message from the source gNB. After receiving the LTM request message, the target gNB may send an LTM request Ack message back to the source gNB, which is a response granting permission for the request.

[0055] The target gNB may send a TA information notification to the source gNB. As mentioned above, the TA information notification may include the TA value, candidate cell ID, RA preamble index, RA-RNTI, gNB-DU ID, and Tag ID pointer. The target gNB may also receive a Cell switch notification from the source gNB. The Cell switch notification may include the target cell ID and TCI state ID.

[0056] Although Figures 4 and 5 illustrate an example where UE200 transitions from a 5G RAN node to a 6G RAN node, the same procedure may be followed when UE200 transitions from a 6G RAN node to a 5G RAN node.

[0057] As illustrated by the operational example described above, when an Xn interface is established between a 5G RAN node and a 6G RAN node, the 5G RAN node and the 6G RAN node (gNB) can exchange messages necessary for handover (HO) or LTM via the Xn interface. Therefore, it becomes possible to perform procedures related to HO or LTM via the Xn interface.

[0058] In this embodiment, not only transition requests (HO request message, LTM request message) but also Early status transfer, SN status transfer, and TA information notification can be sent and received via the Xn interface. Therefore, more accurate and rapid UE transitions can be achieved via the Xn interface.

[0059] (4) Other Embodiments Although embodiments have been described above, it will be obvious to those skilled in the art that the embodiments are not limited to those described and that various modifications and improvements are possible.

[0060] For example, in the above description, 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.

[0061] 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.

[0062] In this disclosure, terms such as “precoding,” “precoder,” “weight (precoding weight),” “quasi-co-location (QCL),” “transmission configuration indication state (TCI state),” “spatial relation,” “spatial domain filter,” “transmit power,” “phase rotation,” “antenna port,” “antenna port group,” “layer,” “number of layers,” “rank,” “resource,” “resource set,” “resource group,” “beam,” “beam width,” “beam angle,” “antenna,” “antenna element,” and “panel” may be used interchangeably.

[0063] Furthermore, the block diagram (Figure 3) used in the description of the above-mentioned embodiments shows functional units. These functional blocks (components) are realized by any combination of at least one of hardware and software. Moreover, 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 also be realized by combining the above one device or the above multiple devices with software.

[0064] Functions include, but are not limited to, judgment, decision, judgment, 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.

[0065] Furthermore, the gNB100 and UE200 (the device) described above may function as a computer that processes the wireless communication method of this disclosure. Figure 6 shows an example of the hardware configuration of the device. As shown in Figure 6, 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.

[0066] 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.

[0067] Each functional block of the device (see Figure 3) is implemented by any hardware element of the computer device, or a combination of such hardware elements.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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).

[0075] 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).

[0076] 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.

[0077] 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 each functional block may be implemented by such hardware. For example, processor 1001 may be implemented using at least one of these hardware components.

[0078] Furthermore, notification of information is not limited to the embodiments 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.

[0079] 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).

[0080] The processing procedures, sequences, flowcharts, etc., of each aspect / embodiment described in this disclosure may be reordered, provided they do not contradict each other. For example, the methods described in this disclosure present various step elements using exemplary order and are not limited to the specific order presented.

[0081] 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 the 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).

[0082] 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.

[0083] 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.

[0084] 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, a comparison with a predetermined value).

[0085] Each aspect / embodiment described in this disclosure 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).

[0086] 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.

[0087] 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 technologies (such as coaxial cable, fiber optic cable, twisted pair, or Digital Subscriber Line (DSL)) and wireless technologies (such as infrared or microwave), then at least one of these wired and wireless technologies is included in the definition of a transmission medium.

[0088] 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.

[0089] 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.

[0090] The terms “system” and “network” as used in this disclosure are interchangeable.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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)).

[0095] 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.

[0096] 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.

[0097] In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

[0098] 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 appropriate term.

[0099] 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 also be a device mounted on a mobile body, the mobile body itself, etc. The mobile body refers to a movable object, and its speed of movement is arbitrary. This also includes the case when the mobile body is stationary. The mobile body includes, but is not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcarts, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones (registered trademark), multicopters, quadcopters, balloons, and items mounted on them. The mobile body may also be a mobile body that moves autonomously based on operation commands. It 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). Furthermore, at least one of the base station and the mobile station may include devices that do not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

[0100] Furthermore, the term "base station" in this disclosure may be interpreted as "mobile station" (user terminal, hereinafter the same). For example, the various aspects / embodiments 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 (or side link).

[0101] 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.

[0102] A wireless frame may consist of one or more frames in the time domain. Each of these one or more frames in the time domain may be called a subframe. 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.

[0103] 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.

[0104] 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.

[0105] 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 PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a mini-slot may be called PDSCH (or PUSCH) mapping type B.

[0106] 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.

[0107] 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 in existing LTE (1ms), a period shorter than 1ms (e.g., 1-13 symbols), or a period longer than 1ms. Note that the unit representing the TTI may be called a slot, minislot, etc., instead of a subframe.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] One or more RBs may also be called a Physical RB (PRB), Sub-Carrier Group (SCG), Resource Element Group (REG), PRB pair, RB pair, etc.

[0116] 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.

[0117] 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.

[0118] A BWP may include BWPs for UL (UL BWP) and BWPs for DL ​​(DL BWP). One or more BWPs may be set within a single carrier for a UE.

[0119] 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".

[0120] 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.

[0121] The terms “connected,” “coupled,” and any variations 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 reinterpreted 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.

[0122] The reference signal can also be abbreviated as Reference Signal (RS), and may be called a pilot depending on the applicable standard.

[0123] 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."

[0124] In the configuration of each of the above devices, "means" may be replaced with "part," "circuit," "device," etc.

[0125] 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.

[0126] 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 be exclusive OR.

[0127] 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.

[0128] The terms “determining” and “determining” as used in this disclosure may encompass a wide variety of actions. “Determining” and “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” and “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 "judgmented" or "decided" after resolving, selecting, choosing, establishing, comparing, etc. In other words, "judgment" and "decision" can include considering something as having "judgmented" or "decided" about some action. Also, "judgment (decision)" can be reinterpreted as "assuming," "expecting," or "considering."

[0129] 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."

[0130] Figure 7 shows an example of the configuration of vehicle 2001. As shown in Figure 7, 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.

[0131] The drive unit 2002 consists 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 consists of a microprocessor 2031, memory (ROM, RAM) 2032, and communication ports (IO ports) 2033. Signals from various sensors 2021 to 2027 provided 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).

[0132] 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.

[0133] The Information Services Unit 2012 consists of various devices for providing (outputting) various types of information such as driving information, traffic information, and entertainment information, including car navigation systems, audio systems, speakers, televisions, and radios, and one or more ECUs that control these devices. The Information Services Unit 2012 uses information acquired from external devices via communication modules 2013, etc., to provide various multimedia information and multimedia services to the occupants of the vehicle 2001.

[0134] Information Services Unit 2012 may include input devices that accept input from external sources (e.g., keyboards, mice, microphones, switches, buttons, sensors, touch panels, etc.) and output devices that perform output to external sources (e.g., displays, speakers, LED lamps, touch panels, etc.).

[0135] 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.

[0136] The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 2001 via its communication port. For example, the communication module 2013 sends and receives data via its 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 of the vehicle 2001.

[0137] 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.

[0138] The communication module 2013 may transmit at least one of the following to an external device via wireless communication: signals from the various sensors 2021 to 2028 input to the electronic control unit 2010, information obtained based on said signals, and information based on input from an external source (user) obtained via the information service unit 2012. The electronic control unit 2010, the various sensors 2021 to 2028, the information service unit 2012, etc., may also be called input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include information based on the above input.

[0139] The communication module 2013 receives various information (traffic information, signal information, vehicle-to-vehicle information, etc.) transmitted from an external device and displays it on the information service unit 2012 installed in the vehicle. The information service unit 2012 may also be called an output unit, which outputs information (for example, outputs information to devices such as displays and speakers based on the PDSCH (or data / information decoded from the PDSCH) received by the communication module 2013). The communication module 2013 also stores the various information received from the external device in a memory 2032 that 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 2021-2028, etc., installed in the vehicle 2001.

[0140] (Note) The above disclosure may be expressed as follows: The first feature is a radio base station comprising: a control unit that operates according to a second radio access technology different from the first radio access technology and performs a terminal transition from a source radio base station according to the first radio access technology; a receiving unit that receives a transition request requesting the transition from the source radio base station via an interface with the source radio base station; and a transmitting unit that transmits a response to the transition request to the source radio base station via the interface.

[0141] The second feature is that, in the first feature, the receiving unit may receive a state transfer message from the source wireless base station via the interface, which transfers specific state information of the terminal.

[0142] A third feature is that, in the first or second feature, the receiving unit may receive a sequence number transfer message from the source radio base station that transfers the state of the sequence number in the packet data convergence protocol layer.

[0143] A fourth feature is that, in the first to third features, the transmitting unit transmits timing-related information, including timing adjustment values ​​for transmission by the terminal, to the source wireless base station via the interface, and the receiving unit may receive a cell switching notification from the source wireless base station via the interface after the transmission of the timing-related information.

[0144] A fifth feature is that, in the first to fourth features, the transmitting unit may transmit a route switching request to the terminal to the core network, and the receiving unit may receive a response to the switching request from the core network.

[0145] This application is based on Japanese Patent Application No. 2025-014091, filed on January 30, 2025. All of its contents are included herein.

[0146] 10 Wireless communication system 20 5GRAN 30 6GRAN 35 6GC 100 gNB 110 Wireless communication unit 120 Network IF unit 130 Message processing unit 140 Control unit 200 UE 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 Rotation speed sensor 2023 Pneumatic 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, Driver assistance system unit 2031, Microprocessor 2032, Memory (ROM, RAM) 2033, Communication port

Claims

1. A radio base station comprising: a control unit that operates according to a second radio access technology different from a first radio access technology and performs terminal transitions from a source radio base station according to the first radio access technology; a receiving unit that receives a transition request requesting the transition from the source radio base station via an interface with the source radio base station; and a transmitting unit that transmits a response to the transition request to the source radio base station via the interface.

2. The radio base station according to claim 1, wherein the receiving unit receives a state transfer message from the source radio base station via the interface, which transfers specific state information of the terminal.

3. The radio base station according to claim 1, wherein the receiving unit receives a sequence number transfer message from the source radio base station that transfers the state of the sequence number in the packet data convergence protocol layer.

4. The radio base station according to claim 1, wherein the transmitting unit transmits timing-related information, including a timing adjustment value for transmission by the terminal, to the source radio base station via the interface, and the receiving unit receives a cell switching notification from the source radio base station via the interface after the transmission of the timing-related information.

5. The wireless base station according to claim 1, wherein the transmitting unit transmits a route switching request to the terminal to the core network, and the receiving unit receives a response to the switching request from the core network.

6. A wireless communication method at a radio base station, comprising the steps of: operating in accordance with a second radio access technology different from a first radio access technology and performing a terminal transition from a source radio base station in accordance with the first radio access technology; receiving a transition request requesting the transition from the source radio base station via an interface with the source radio base station; and transmitting a response to the transition request to the source radio base station via the interface.

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