Terminal apparatus that efficiently changes connection-target cells, and control method

Patent metadata

Field	Value
Publication number	US-2025081051-A1
Application number	US-202418950581-A
Country	US
Kind code	A1
Filing date	Nov 18, 2024
Priority date	Sep 27, 2022
Publication date	Mar 6, 2025
Grant date	—

Abstract

A base station sets, to a terminal apparatus, in advance control parameters used when performing communication using, as a primary cell, a cell used as a secondary cell, thereby omitting, when changing the cell from the secondary cell to the primary cell, setting of necessary parameters.

First claim

What is claimed is:

1 . A terminal apparatus that communicates with a base station apparatus using a primary cell and a secondary cell through carrier aggregation, the terminal apparatus comprising:
a first receiving unit configured to receive parameters required when one or more cells are used as primary cells, respectively, and parameters required when the one or more cells are used as secondary cells, respectively; a changing unit configured to change a first cell among the one or more cells to a primary cell in a case where the first cell is being used as a secondary cell; and a second receiving unit configured to receive, from the base station apparatus, information regarding whether or not to continue to use, as a secondary cell, a second cell that will be no longer a primary cell after the first cell is changed to a primary cell.

2 . The terminal apparatus according to claim 1 , further comprising:
a determination unit configured to, when the second receiving unit receives an instruction to continue to use the second cell as a secondary cell, determine whether or not a CDRX (connected discontinuous reception) control parameter of the second cell is the same parameter in a case where the second cell is used as a primary cell and in a case where the second cell is used as a secondary cell; and a timer control unit configured to continue a timer related to CDRX control that is running, without stopping the timer, in a case where the determination unit determines that the CDRX control parameter is the same and the second cell is changed to a secondary cell.

3 . The terminal apparatus according to claim 1 , further comprising:
a determination unit configured to determine whether or not a parameter related to beam control of the second cell is the same parameter in a case where the second cell is used as a primary cell and a case where the second cell is used as a secondary cell, when the second receiving unit receives an instruction to continue to use the second cell as a secondary cell; and a beam recovery processing continuing unit configured to continue beam recovery processing instead of stopping the beam recovery processing upon a change of the second cell to a secondary cell, in a case where the determination unit determines that the parameter related to beam control is the same, and the beam recovery processing had been started when the second cell was being used as a primary cell.

4 . The terminal apparatus according to claim 1 , further comprising:
a determination unit configured to determine whether or not HARQ-related setting for the first cell is the same in a case where the first cell is used as a primary cell and a case where the first cell is used as a secondary cell; and a buffer control unit configured to hold data held in a HARQ soft buffer of the terminal apparatus instead of erasing the data, if the determination unit determines that the HARQ (hybrid automatic repeat request)-related setting is the same.

5 . The terminal apparatus according to claim 1 , wherein
wherein the first receiving unit receives a parameter using an RRC Reconfiguration message, and when changing the first cell to a primary cell, the changing unit obtains a value of an RNTI (a radio network temporary identifier) that is used after a change of the first cell to a primary cell, from the base station apparatus using MAC CE (media access control/control element) or DCI (downlink control information).

6 . The terminal apparatus according to claim 1 , wherein
the first receiving unit receives, as parameters required when the one or more cells are used as primary cells, an RRC Reconfiguration message that includes a value of RNTI (radio network temporary identifier) that is used after the one or more cells are set as primary cells and the primary cells are changed, the changing unit changes the first cell to a primary cell in accordance with receiving an instruction given from the base station apparatus using MAC CE (media access control/control element) or DCI (downlink control information), and a value of RNTI received by the first receiving unit is used with respect to the first cell after the first cell has changed to a primary cell.

7 . The terminal apparatus according to claim 1 , wherein
when changing the first cell to a primary cell, the changing unit executes random access control on the primary cell.

8 . The terminal apparatus according to claim 7 , further comprising
a timer control unit configured to determine whether the random access control was successful or failed.

9 . The terminal apparatus according to claim 8 , wherein
the timer control unit includes:
a starting unit configured to start a timer at a timing when the changing unit instructs a change,
a timer stopping unit configured to stop a timer upon success of random access control, and
a timer expiration determination unit configured to determine whether or not a started timer expires,
wherein the terminal apparatus further includes a determination unit configured to determine that a switch of a primary cell was successful or failed, based on a result of successful or failed random access control performed by the timer control unit.

10 . The terminal apparatus according to claim 9 , wherein
if the timer expiration determination unit determines that a timer has expired without random access control being successful, the determination unit determines that a switch to a primary cell failed.

11 . The terminal apparatus according to claim 10 , further comprising
a reconnection processing starting unit configured to start reconnection processing in accordance with the determination unit determining that a switch to a primary cell failed.

12 . A control method performed by a terminal apparatus that communicates with a base station apparatus using a primary cell and a secondary cell through carrier aggregation, the method comprising:
receiving parameters required when one or more cells are used as primary cells, respectively, and parameters required when the one or more cells are used as secondary cells, respectively; changes a first cell among the one or more cells to a primary cell in a case where the first cell is being used as a secondary cell; and receiving, from the base station apparatus, information regarding whether or not to continue to use, as a secondary cell, a second cell that will be no longer a primary cell after the first cell is changed to a primary cell.

Assignees

• Kddi Corp

Inventors

• Takeda Hiroki
• Li Yanwei
• Takaku Yoshitaka

Classifications

• H04L5/001

  the frequencies being arranged in component carriers · CPC title

• H04B7/06964

  Re-selection of one or more beams after beam failure · CPC title

• H04W76/28

  Discontinuous transmission [DTX]; Discontinuous reception [DRX] · CPC title

• H04L5/0098

  Signalling of the activation or deactivation of component carriers, subcarriers or frequency bands · CPC title

• H04W76/15

  Setup of multiple wireless link connections · CPC title