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EP-4742759-A1 - RADIO BASE STATION AND RADIO COMMUNICATION METHOD

EP4742759A1EP 4742759 A1EP4742759 A1EP 4742759A1EP-4742759-A1

Abstract

A radio base station receives from a candidate secondary node, connection information necessary for connection with the candidate secondary node when a terminal transitions between secondary nodes in accordance with mobility control by a lower layer, and transmits the received connection information to a transition source secondary node or to the terminal.

Inventors

  • MIN TIANYANG

Assignees

  • NTT DOCOMO, INC.

Dates

Publication Date
20260513
Application Date
20240821

Claims (6)

  1. A radio base station comprising: a receiving unit that receives from a candidate secondary node, connection information necessary for connection with the candidate secondary node when a terminal transitions between secondary nodes in accordance with mobility control by a lower layer; and a transmitting unit that transmits the received connection information to a transition source secondary node or to the terminal.
  2. The radio base station according to claim 1, wherein the connection information includes at least any one of an uplink timing adjustment value, a transmission configuration indication, and an active bandwidth part in the candidate secondary node.
  3. The radio base station according to claim 1, wherein the transmitting unit transmits the connection information to the terminal using a control element of a medium access control layer.
  4. The radio base station according to claim 2, wherein the receiving unit receives the timing adjustment value from the candidate secondary node separately from the connection information.
  5. The radio base station according to claim 4, wherein the transmitting unit transmits to the candidate secondary node, information indicating that the terminal transitions to the candidate secondary node.
  6. A radio communication method in a master node, comprising: a step of receiving from a candidate secondary node, connection information necessary for connection with the candidate secondary node when a terminal transitions between secondary nodes in accordance with mobility control by a lower layer; and a step of transmitting the received connection information to a transition source secondary node or to the terminal.

Description

Technical Field The present disclosure relates to a radio base station and a radio communication method that support L1/L2 mobility. Background Art 3rd Generation Partnership Project (3GPP: registered trademark) is developing specifications for 5th generation mobile communication systems (5G, also referred to as New Radio (NR) or Next Generation (NG)), and is also developing specifications for next generation communication systems referred to as Beyond 5G, 5G Evolution, or 6G. For example, in 3GPP Release 18, extension of layer 1/layer 2 mobility (L1/L2 mobility) is discussed. L1/L2 mobility is also referred to as Lower layer Triggered Mobility (LTM), corresponds to a technique related to mobility of a terminal (User Equipment, UE) in layer 1 or layer 2, and includes transition (handover (HO)) of the UE to another cell or the like (Non Patent Literature 1). The HO by L1/L2 mobility is realized by a lower layer such as a media access control layer (MAC). Regarding such LTM, it has been discussed that during dual connectivity (DC) in which simultaneous communication is performed between the UE and each of two NG-RAN Nodes, Timing Advance (TA) for adjusting transmission timing of an uplink (UL), TCI (Transmission Configuration Indication) state of a target cell, and information (connection information) on an active bandwidth part (BWP) should be provided to the UE (Non Patent Literature 1). Citation List Non-Patent Literature Non-Patent Literature 1: "Signalling approaches for LTM cell switch execution", R2-2308438, 3GPP TSG-RAN WG2 Meeting #123, 3GPP, August, 2023. Summary of Invention However, in the case of LTM (Inter-SN LTM) between secondary nodes (SNs), there is a problem that in the current LTM operation, the connection information of the target cell (candidate cell) described above cannot be provided from an SN to the UE. Further, in the case of Inter-SN LTM, there is also a problem that early TA acquisition for acquiring TA early cannot be performed. Thus, in the case of Inter-SN LTM, there is a concern that appropriate mobility control cannot be performed depending on status of a candidate cell(s). Therefore, the following disclosure has been made in view of such a situation, and an object of the disclosure is to provide a radio base station and a radio communication method capable of achieving appropriate mobility control depending on status of a candidate cell(s) and the like even in the case of Inter-SN LTM. According to an aspect of the present disclosure, there is provided a radio base station (gNB 100) including: a receiving unit (handover processing unit 120) that receives from a candidate secondary node, connection information necessary for connection with the candidate secondary node when a terminal transitions between secondary nodes in accordance with mobility control by a lower layer; and a transmitting unit (handover processing unit 120) that transmits the received connection information to a transition source secondary node or to the terminal. According to an aspect of the present disclosure, there is provided a terminal(UE 200) including: a receiving unit (handover execution unit 230) that receives from a radio base station, a start instruction that explicitly or implicitly instructs a start of monitoring of a specific execution condition used for mobility control by a lower layer; and a control unit (control unit 240) that starts monitoring of the execution condition based on the received start instruction. Brief Description of Drawings [FIG. 1] FIG. 1 is an overall schematic configuration diagram of a radio communication system 10.[FIG. 2] FIG. 2 is a diagram illustrating an example of control by L1/L2 mobility.[FIG. 3] FIG. 3 is a functional block configuration diagram of a gNB 100.[FIG. 4] FIG. 4 is a functional block configuration diagram of a UE 200.[FIG. 5] FIG. 5 is a diagram illustrating an example (example 1) of communication sequence of Inter-SN LTM according to operation example 2.[FIG. 6] FIG. 6 is a diagram illustrating an example (example 2) of the communication sequence of Inter-SN LTM according to operation example 2.[FIG. 7] FIG. 7 is a diagram illustrating an example (example 1) of communication sequence of UE based LTM according to operation example 3.[FIG. 8] FIG. 8 is a diagram illustrating an example (example 2) of the communication sequence of UE based LTM according to operation example 3.[FIG. 9] FIG. 9 is a diagram illustrating an example of a hardware configuration of the gNB 100 and the UE 200.[FIG. 10] FIG. 10 is a diagram illustrating a configuration example of a vehicle 2001. Description of Embodiments Hereinafter, embodiments will be described with reference to the drawings. Note that the same functions and configurations are denoted by the same or similar reference numerals, and descriptions of the functions and configurations will be appropriately omitted. (1) Overall Schematic Configuration of Radio Communication System FIG. 1 is an overall schematic