US-12628125-B2 - User equipment and base station device

Abstract

A user equipment includes a receiving unit configured to receive a first number of multiple input multiple output (MIMO) layers and a second number of MIMO layers from a base station device, a control unit configured to select the first number of MIMO layers or the second number of MIMO layers for an activated bandwidth part (BWP) based on a type of the activated BWP, and a communication unit configured to perform communication using the selected number of MIMO layers, in which the first number of MIMO layers is a number of MIMO layers configured for a default BWP or an initial BWP, and the second number of MIMO layers is a number of MIMO layers configured for each cell.

Inventors

• Hideaki Takahashi
• Tooru Uchino
• Tomoya OHARA

Assignees

• NTT DOCOMO, INC.

Dates

Publication Date

20260512

Application Date

20190328

Claims (7)

1. 1 . A terminal comprising: a receiver that receives, from a base station: a first number of multiple-input multiple-output (MIMO) layers; and a second number of MIMO layers configured in each cell; a processor that applies, based on a type of a bandwidth part (BWP), the first number of MIMO layers or the second number of MIMO layers to the BWP when a cell in which the second number of MIMO layers is configured is activated; and a transceiver that performs communication with the base station using the BWP, wherein the second number of MIMO layers configured in each cell is transmitted to the terminal through a serving cell configuration, wherein when a default BWP is not designated by higher layer signaling, an initial downlink (DL) BWP is used as the default BWP, and wherein, when an activated DL BWP is neither the default nor the initial DL BWP, the processor applies the second number of MIMO layers configured in each cell as transmitted through the serving cell configuration.
2. 2 . The terminal according to claim 1 , wherein the processor applies the first number of MIMO layers to the BWP in a case where the BWP is an initial BWP, and applies the second number of MIMO layers to the BWP in a case where the BWP is not the initial BWP.
3. 3 . The terminal according to claim 2 , wherein the first number of MIMO layers is less than the second number of MIMO layers.
4. 4 . The terminal according to claim 1 , wherein the first number of the MIMO layers is used when a discontinuous reception (DRX) cycle is equal to or longer than a predetermined period.
5. 5 . The terminal according to claim 1 , wherein the type of the BWP is specified by higher layer signaling.
6. 6 . A base station comprising: a transmitter that transmits, to a terminal: a first number of multiple-input multiple-output (MIMO) layers; and a second number of MIMO layers configured in each cell; a processor that applies, based on a type of a bandwidth part (BWP), the first number of MIMO layers and the second number of MIMO layers to the BWP when a cell in which the second number of MIMO layers is configured is activated; and a transceiver that performs communication with the terminal using the BWP, wherein the transmitter transmits the second number of MIMO layers configured in each cell through a serving cell configuration, wherein when a default BWP is not designated by higher layer signaling, an initial downlink (DL) BWP is used as the default BWP, and wherein, when an activated DL BWP is neither the default nor the initial DL BWP, the processor applies the second number of MIMO layers configured in each cell as transmitted through the serving cell configuration.
7. 7 . A communication method performed by a terminal, the method comprising: receiving, from a base station: a first number of multiple-input multiple-output (MIMO) layers; and a second number of MIMO layers configured in each cell; applying, based on a type of a bandwidth part (BWP), the first number of MIMO layers or the second number of MIMO layers to the BWP when a cell in which the second number of MIMO layers is configured is activated; and performing communication with the base station using the BWP, wherein the second number of MIMO layers configured in each cell is transmitted to the terminal through a serving cell configuration, wherein when a default BWP is not designated by higher layer signaling, an initial downlink (DL) BWP is used as the default BWP, and wherein, when an activated DL BWP is neither the default nor the initial DL BWP, the processor applies the second number of MIMO layers configured in each cell as transmitted through the serving cell configuration.

Description

TECHNICAL FIELD The present invention relates to a user equipment and a base station device in a wireless communication system. BACKGROUND ART In New Radio (NR) (also referred to as “5G”) which is a successor system of Long Term Evolution (LTE), a technology satisfying a large-capacity system, a high-speed data transmission rate, a low delay, simultaneous connection of multiple terminals, a low cost, power saving, and the like is under review (for example, Non-Patent Document 1). In NR, a method in which a user equipment uses a part of a carrier bandwidth as a bandwidth part (BWP) is used. The BWP is configured with continuous physical resource blocks (PRBs). Further, a maximum of four BWPs can be configured in the user equipment in each of DL or UL. In a case in which a plurality of BWPs are configured, the user equipment executes communication using one active BWP (for example, Non-Patent Document 2). CITATION LIST Non-Patent Document Non-Patent Document 1: 3GPP TS 38.300 V15.3.0 (2018 September)Non-Patent Document 2: 3GPP TS 38.213 V15.3.0 (2018 September) SUMMARY OF THE INVENTION Problem to be Solved by the Invention In an NR wireless communication system, a bandwidth used by the user equipment can be reduced using a BWP mechanism. However, in a case in which the number of multiple input multiple output (MIMO) layers configured in the user equipment is large, it is difficult to reduce power consumption. The present invention has been made in light of the foregoing, and it is an object of the present invention to improve communication efficiency by using an appropriate number of MIMO layers by the user equipment in a wireless communication system. Means for Solving Problem According to the disclosed technique, a user equipment including a receiving unit configured to receive a first number of multiple input multiple output (MIMO) layers and a second number of MIMO layers from a base station device, a control unit configured to select the first number of MIMO layers or the second number of MIMO layers for an activated bandwidth part (BWP) based on a type of the activated BWP, and a communication unit configured to perform communication using the selected number of MIMO layers, in which the first number of MIMO layers is a number of MIMO layers configured for a default BWP or an initial BWP, and the second number of MIMO layers is a number of MIMO layers configured for each cell is provided. Effect of the Invention According to the disclosed technology, communication efficiency can be improved by using an appropriate number of MIMO layers by the user equipment in a wireless communication system. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram for describing a wireless communication system in an embodiment of the present invention; FIG. 2 is a diagram for describing a BWP; FIG. 3 is a sequence diagram for describing an example (1) of a communication configuration; FIG. 4 is a sequence diagram for describing an example (2) of a communication configuration; FIG. 5 is a flowchart for describing a first operation example in an embodiment of the present invention; FIG. 6 is a specification change example (1) related to a first operation example in an embodiment of the present invention; FIG. 7 is a specification change example (2) related to a first operation example in an embodiment of the present invention; FIG. 8 is a specification change example (3) related to a first operation example in an embodiment of the present invention; FIG. 9 is a specification change example (4) related to a first operation example in an embodiment of the present invention; FIG. 10 is a specification change example (5) related to a first operation example in an embodiment of the present invention; FIG. 11 is a flowchart for describing a second operation example in an embodiment of the present invention; FIG. 12 is a specification change example (1) related to a second operation example in an embodiment of the present invention; FIG. 13 is a specification change example (2) related to a second operation example in an embodiment of the present invention; FIG. 14 is a specification change example (3) related to a second operation example in an embodiment of the present invention; FIG. 15 is a specification change example (4) related to a second operation example in an embodiment of the present invention; FIG. 16 is a specification change example (5) related to a second operation example in an embodiment of the present invention; FIG. 17 is a flowchart for describing a third operation example in an embodiment of the present invention; FIG. 18 is a specification change example (1) related to a third operation example in an embodiment of the present invention; FIG. 19 is a specification change example (2) related to a third operation example in an embodiment of the present invention; FIG. 20 is a specification change example (3) related to a third operation example in an embodiment of the present invention; FIG. 21 is a specification c