# US 9,439,198 B2 · Radio base station, radio communication system and radio communication method

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- Number: US 9,439,198 B2
- Document ID: US9439198B2
- Status: Granted
- Kind: B2
- Application number: 14/387,383
- Filed: 2013-02-08
- Published: 2015-04-02
- Granted: 2016-09-06
- Earliest claimed: 2012-03-30
- Assignees: Ntt Docomo, Inc.
- Applicants: Ntt Docomo, Inc.
- Inventors: Yuki Inoue; Satoshi Nagata; Takehiro Nakamura
- Web page: https://patentgrep.com/patent/US9439198B2

## CPC

- H04W 72/046: {the resource being in the space domain, e.g. beams}
- H04B 7/0615: {of weighted versions of same signal}
- H04B 7/0697: {using spatial multiplexing}
- H04W 16/28: using beam steering
- H04W 52/143: {Downlink power control}
- H04W 52/343: {taking into account loading or congestion level}
- H04W 16/08: Load shedding arrangements
- H04W 16/30: Special cell shapes, e.g. doughnuts or ring cells
- H04W 52/42: in systems with time, space, frequency or polarisation diversity
- H04W 72/0446: Resources in time domain, e.g. slots or frames
- H04W 72/52: based on load
- H04W 88/08: Access point devices
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04B: TRANSMISSION

## Abstract

The present invention is designed to make effective use of radio resources in VSEC to output a plurality of beams of varying tilt angles for sectorization in vertical directions. A radio communication method for a radio base station that outputs a plurality of beams of varying tilt angles and forms a plurality of cells that are sectorized vertically, and a user terminal that establishes wireless connection with the radio base station, provides the steps in which the radio base station acquires information about the communication capacity of each of the plurality of cells, and controls the vertical plane beam width and/or transmission power of each cell and sets the coverage area of each cell so that differences in communication capacity between the plurality of cells are reduced.

## Claims

### Claim 1

A radio communication method for a radio base station that outputs a plurality of beams of varying tilt angles and forms a plurality of cells in a vertical direction, and a user terminal that establishes wireless connection with the radio base station, the radio communication method comprising the steps in which:
the radio base station:
acquires information about communication capacity of each of the plurality of cells; and
sets the amount of resources to allocate to a cell having lower communication capacity among the plurality of cells lower than for a cell having higher communication capacity,
wherein the radio base station makes at least one of a frequency range to allocate resources to the call having lower communication capacity among the plurality of cells and a time period to allocate resources, narrower than for the cell having higher communication capacity,
wherein the radio base station provides a time period to allocate resources to the cell having higher communication capacity and not allocate resources to the cell having lower communication capacity, and, in the time period, increases the transmission power of the cell having higher communication capacity, and
wherein, in the time period, the radio base station changes a tilt angle of the beam forming the cell having higher communication capacity so that a coverage area of the cell having higher communication capacity expands in a direction of the coverage area of the cell having lower communication capacity formed outside the time period.

### Claim 2

A radio communication method for a radio base station that outputs a plurality of beams of varying tilt angles and forms a plurality of cells in a vertical direction, and a user terminal that establishes wireless connection with the radio base station, the radio communication method comprising the steps in which:
the radio base station:
acquires information about communication capacity of each of the plurality of cells;
selects a predetermined user terminal that can connect with a cell having lower communication capacity with predetermined quality or above, among user terminals that are present in a coverage area of a cell having higher communication capacity among the plurality of cells; and
provides a time period to allocate resources to the cell having lower communication capacity and not allocate resources to the cell having higher communication capacity, and, in the time period, allocate resources to the predetermined user terminal from the cell having lower communication capacity,
wherein, in the time period, the radio base station changes at least one of a tilt angle and a vertical plane beam width of a beam to form the cell having lower communication capacity so that a coverage area of the cell having lower communication capacity expands in a direction of the coverage area of the cell having higher communication capacity formed outside the time period.

### Claim 3

A radio base station that forms a plurality of cells in a vertical direction, the radio base station comprising:
an antenna section configured to output a plurality of beams of varying tilt angles and form a plurality of cells;
an information acquiring section configured to acquire information about communication capacity of each of the plurality or cells; and
a control section configured to set the amount of resources to allocate to a cell having lower communication capacity among the plurality of cells lower than for a cell having higher communication capacity,
wherein the control section makes at least one of a frequency range to allocate resources to the cell having lower communication capacity among the plurality of cells and a time period to allocate resources, narrower than for the cell having higher communication capacity,
wherein the control provides a time period to allocate resources to the cell having higher communication capacity and not allocate resources to the cell having lower communication capacity, and, in the time period, increases the transmission power of the cell having higher communication capacity,
wherein, in the time period, the control section changes a tilt angle of the beam forming the cell having higher communication capacity so that a coverage area of the cell having higher communication capacity expands in a direction of the coverage area of the cell having lower communication capacity formed outside the time period.

### Claim 4

A radio communication system comprising a radio base station that forms a plurality of cells in a vertical direction and a user terminal that establishes wireless connection with the radio base station, wherein the radio base station comprises:
an antenna section configured to output a plurality of beams of varying tilt angles and form a plurality of cells;
an information acquiring section configured to acquire information about communication capacity of each of the plurality of cells; and
a control section configured to set the amount of resources to allocate to a cell having lower communication capacity among the plurality of cells lower than for a cell having higher communication capacity,
wherein the control section makes at least one of a frequency range to allocate resources to the cell having lower communication capacity among the plurality of cells and a time period to allocate resource, narrower than for the cell having higher communication capacity,
wherein the control section provides a time period to allocate to the cell having higher communication capacity and not allocate resources to the cell having lower communication capacity, and, in the time period, increases the transmission power of the cell having higher communication capacity,
wherein, in the time period, the control section changes a tilt angle of the beam forming the cell having higher communication capacity so that a coverage area of the cell having higher communication capacity expands in a direction of the area of the cell having lower communication capacity formed outside the time period.