# US 10,455,579 B2 · User terminal, radio base station, and radio communication method

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- Number: US 10,455,579 B2
- Document ID: US10455579B2
- Status: Granted
- Kind: B2
- Application number: 15/514,036
- Filed: 2015-09-25
- Published: 2017-10-05
- Granted: 2019-10-22
- Earliest claimed: 2014-09-25
- Assignees: Ntt Docomo, Inc.
- Applicants: Ntt Docomo, Inc.
- Inventors: Kazuaki Takeda; Shimpei Yasukawa; Satoshi Nagata
- Web page: https://patentgrep.com/patent/US10455579B2

## CPC

- H04W 72/0453: Resources in frequency domain, e.g. a carrier in FDMA
- H04W 72/04: Wireless resource allocation
- H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal
- H04W 74/08: Non-scheduled access, e.g. ALOHA (hybrid access H04W74/02)
- H04W 74/0833: Random access procedures, e.g. with 4-step access
- H04W 88/02: Terminal devices
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

According to the present invention, in an LTE system, communication can appropriately carried out even in the case where a bandwidth utilized in the transmission/receiving of data signals and control signals is configured narrower than the system bandwidth. According to an embodiment, a user terminal is configured to carry out communication with a radio base station using a narrow bandwidth that is limited to a narrower bandwidth than a system bandwidth. The user terminal includes a decision section configured to decide a frequency position for the narrow bandwidth to be arranged, based on given information; and a receiving section configured to receive a control signal and a data signal that are allocated on the narrow bandwidth based on the frequency position. The narrow bandwidth is arranged at different frequency positions per a predetermined period of time.

## Claims

### Claim 1

A user terminal communicating with use of a narrow bandwidth that is limited to a part of a system band, the user terminal comprising:
a decision section that decides a frequency position for the narrow bandwidth; and
a receiving section that receives a downlink signal allocated to the narrow bandwidth based on the frequency position,
wherein the receiving section uses symbols included in first to third symbols of a subframe to tune to the frequency position without reading the Physical Downlink Control Channel (PDCCH) in the first to third symbols.

### Claim 2 (depends on 1)

The user terminal according to claim 1, wherein
the decision section decides a frequency position of a downlink control channel that is frequency-division-multiplexed with a Physical Downlink Shared Channel (PDSCH), and
the receiving section monitors the downlink control channel in a common search space that is common to a plurality of user terminals.

### Claim 3 (depends on 2)

The user terminal according to claim 2, wherein
the receiving section monitors the downlink control channel in the common search space and a user terminal-specific search space that varies among user terminals, and
the common search space and the user terminal-specific search space are allocated to different subframes.

### Claim 4 (depends on 2)

The user terminal according to claim 2, wherein the decision section decides a subframe to which the common search space is allocated, on the basis of information provided from a radio base station.

### Claim 5

A radio communication method for a user terminal communicating with use of a narrow bandwidth that is limited to a part of a system band, the radio communication method comprising:
deciding a frequency position for the narrow bandwidth; and
receiving a downlink signal allocated to the narrow bandwidth based on the frequency position,
wherein the user terminal uses symbols included in first to third symbols of a subframe to tune to the frequency position without reading the Physical Downlink Control Channel (PDCCH) in the first to third symbols.