# US 9,439,157 B2 · Radio base station and method for controlling transmission power in radio base station

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- Number: US 9,439,157 B2
- Document ID: US9439157B2
- Status: Granted
- Kind: B2
- Application number: 14/572,986
- Filed: 2014-12-17
- Published: 2015-07-16
- Granted: 2016-09-06
- Earliest claimed: 2014-01-16
- Assignees: Fujitsu Limited
- Applicants: Fujitsu Limited
- Inventors: Dai Kimura
- Web page: https://patentgrep.com/patent/US9439157B2

## CPC

- H04W 52/245: {taking into account received signal strength}
- H04W 52/143: {Downlink power control}
- H04W 52/281: {taking into account user or data type priority}
- H04W 52/346: {distributing total power among users or channels}
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

A radio base station measures a reception power of a downlink radio signal transmitted for a first radio area and controls a transmission power of a downlink radio signal to be transmitted for a second radio area according to the measured reception power.

## Claims

### Claim 1

A radio base station that measures a reception power of a downlink radio signal transmitted for a first radio area and controls a transmission power for a radio resource assigned to a downlink radio signal to be transmitted for a second radio area according to the measured reception power, the radio resource including a plurality of resource units obtained by dividing the radio resource in a frequency domain, the control being performed by increasing a per-unit transmission power that is a transmission power per resource unit and decreasing a number of the resource units assigned to the downlink radio signal.

### Claim 2 (depends on 1)

The radio base station according to claim 1, wherein the control is performed such that the per-unit transmission power increases as the measured reception power increases.

### Claim 3 (depends on 1)

The radio base station according to claim 1, wherein the decrease in the number of the resource units is performed by narrowing a system bandwidth.

### Claim 4 (depends on 1)

The radio base station according to claim 1, wherein the decrease in the number of the resource units is performed by not assigning a resource unit assignable to data to the downlink radio signal.

### Claim 5 (depends on 4)

The radio base station according to claim 4, wherein the resource unit that is not assigned to the downlink radio signal is selected such that a resource unit, a frequency of which is different from a frequency of a resource unit assigned to data in a third radio area formed in the first radio area, is assigned to data in the second radio area.

### Claim 6 (depends on 1)

The radio base station according to claim 1, wherein a per-unit transmission power of a resource unit assigned to a second signal to be received by a radio terminal in priority to a first signal is higher than a per-unit transmission power of a resource unit assigned to the first signal.

### Claim 7 (depends on 6)

The radio base station according to claim 6, wherein the second signal includes at least one of a reference signal, a broadcast signal, and a synchronization signal.

### Claim 8 (depends on 1)

The radio base station according to claim 1, wherein the control is not performed when a number of radio terminals accommodated in the second radio area is greater than a threshold value.

### Claim 9 (depends on 1)

The radio base station according to claim 1, wherein the radio base station estimates a number of radio terminals newly accommodatable in the second radio area by the control and does not perform the control when the estimated number of the radio terminals is less than a threshold value.

### Claim 10 (depends on 1)

The radio base station according to claim 1, wherein the radio base station measures a reception power of a downlink radio signal to be transmitted for a third radio area formed in the first radio area and performs the control based on reception powers respectively measured for the first radio area and the third radio area.

### Claim 11

A method for controlling a transmission power in a radio base station, the method comprising:
measuring a reception power of a downlink radio signal transmitted for a first radio area; and
controlling a transmission power for a radio resource assigned to a downlink radio signal to be transmitted for a second radio area according to the measured reception power, the radio resource including a plurality of resource units obtained by dividing the radio resource in a frequency domain, the control being performed by increasing a per-unit transmission power that is a transmission power per resource unit and decreasing a number of the resource units assigned to the downlink radio signal.

### Claim 12 (depends on 11)

The method for controlling the transmission power in the radio base station according to claim 11, wherein the control is performed such that the per-unit transmission power increases as the measured reception power increases.