# US 11,115,174 B2 · Base station, user terminal, radio communication system, and communication control method

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- Number: US 11,115,174 B2
- Document ID: US11115174B2
- Status: Granted
- Kind: B2
- Application number: 15/317,570
- Filed: 2015-04-23
- Published: 2017-05-18
- Granted: 2021-09-07
- Earliest claimed: 2014-07-01
- Assignees: Ntt Docomo, Inc.
- Applicants: Ntt Docomo, Inc.
- Inventors: Kazuki Takeda; Hiroki Harada; Satoshi Nagata
- Web page: https://patentgrep.com/patent/US11115174B2

## CPC

- H04L 5/14: Two-way operation using the same type of signal, i.e. duplex
- H04B 7/2656: {for structure of frame, burst}
- H04L 5/005: {of common pilots, i.e. pilots destined for multiple users or terminals}
- H04L 5/0051: {of dedicated pilots, i.e. pilots destined for a single user or terminal}
- H04L 5/1469: {using time-sharing}
- H04W 72/1268: of uplink data flows
- H04L 5/0044: {Allocation of payload; Allocation of data channels, e.g. PDSCH or PUSCH}
- Y02D 30/70: in wireless communication networks
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04B: TRANSMISSION
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

A radio communication system includes one or more user terminals and one or more base stations that execute time division radio communication using a time division duplex (TDD) system. A radio frame is a radio communication resource used in the time division radio communication, and includes a downlink subframe that is a transmission period of a downlink signal, a special subframe including a guard period that is used neither for transmission of a downlink signal nor for transmission of an uplink signal, and an extended subframe that is used as either a transmission period of a downlink signal or a transmission period of an uplink signal, in accordance with a scheduling by the base station.

## Claims

### Claim 1

A user terminal that communicates with a primary cell and a secondary cell by radio, comprising:
a receiver that receives a higher layer signaling; and
a controller that sets:
a first communication usage of a first radio communication resource, which is divided into periods of communication usage, to be used in the primary cell and
a second communication usage, which is divided into periods of communication usage, of a second radio communication resource to be used in the secondary cell, based on the higher layer signaling,
wherein, based on the higher layer signaling, the controller uses the first radio communication resource and the second communication resource as a radio communication resource including a period of communication usage of the respective periods of communication usage that is neither a period for transmission of a downlink signal nor a period for transmission of an uplink signal.

### Claim 2 (depends on 1)

The user terminal according to claim 1,
wherein, in a case where, based on the higher layer signaling, the controller sets the second communication usage of the second radio communication resource used in the secondary cell to be transmission of a downlink signal, and sets the first communication usage of the first radio communication resource used in the primary cell to be transmission of an uplink signal,
the controller feeds back an Acknowledgement (ACK) or a Negative Acknowledgement (NACK) for the second radio communication resource to be used in the secondary cell, by using the first radio communication resource to be used in the primary cell.

### Claim 3 (depends on 1)

The user terminal according to claim 1, wherein the receiver executes an operation of receiving a downlink signal in the secondary cell, based on a terminal-specific reference signal that is specific to the user terminal and is transmitted from the secondary cell.

### Claim 4

A control method for a user terminal that communicates with a primary cell and a secondary cell by radio, comprising:
receiving a higher layer signaling;
setting a first communication usage of a first radio communication resource, which is divided into periods of communication usage, to be used in the primary cell; and
setting a second communication usage of a second radio communication resource, which is divided into periods of communication usage, to be used in the secondary cell, based on the higher layer signaling,
wherein, based on the higher layer signaling, the user terminal uses the first radio communication resource and the second communication resource as a radio communication resource including a period of communication usage of the respective periods of communication usage that is neither a period for transmission of a downlink signal nor a period for transmission of an uplink signal.