WIRELESS BASE STATION FOR CONTROLLING ANTENNA TRANSMISSION POWER

• US 20120140658A1
• Filed: 12/01/2011
• Published: 06/07/2012
• Est. Priority Date: 12/03/2010
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: KANZAKI, Hajime, Fujishima, Kenzaburo, Kuwahara, Mikio, Tsunehara, Katsuhiko
• Granted Patent: US 8,891,390 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04B 7/0426 Power distribution
• CPC Class Codes: H04B 7/068 using space frequency diversity space-frequency coding H04L1/0606

Abstract

Provided is a wireless communication system which includes a wireless communication unit using plural frequency bands and plural antennas. The system changes the transmission power of each antenna, based on the interference of each of the frequency bands from the neighbor base station along the antenna direction. The system estimates the number of antennas necessary for transmission in response to a user requirement, and determines a necessary antenna in accordance with the antenna direction in which the terminal is located, and further changes the transmission power of each antenna.

Claims

1. A wireless base station comprising:

at least one antenna or an antenna group which communicates with a terminal in a plurality of frequency bands;

a communication control unit that assigns an individual wireless resource in a frame to a terminal located in its belonging cell area, and controls transmitting and receiving of data to and from the terminal using the wireless resource; and

a beam pattern determination unit that determines transmission power of the antenna or antenna group, based on at least one of interference power that the terminal is subject to, a direction in which the interference arrives, and received power of a transmission signal from the terminal by the antenna or antenna group, in each of the plurality of frequency bands.

2. The wireless base station according to claim 1, wherein

the base station instructs a plurality of terminals to measure the interference, and estimates an arrival direction of the interference in the plurality of frequency bands based on the received power of the antenna or antenna group represented a report corresponding to the instruction.

3. The wireless base station according to claim 1, wherein

the wireless base station

controls a neighbor base station to report transmission power of an antenna or antenna group of the neighbor base station in each of the plurality of frequency bands, location information of the neighbor base station, and direction information of the antenna or antenna group, and

estimates interference power and an arrival direction of the interference, based on the transmission power of the antenna or antenna group of the neighbor base station and the location information.

4. The wireless base station according to claim 1, wherein

the beam pattern determination unit includes a first beam pattern determination unit which changes the transmission power of the antenna or antenna group, in accordance with the interference power, and

the first beam pattern determination unit decrements the transmission power of the antenna or antenna group whose interference power is greater than a first threshold value, and decrements the transmission power of the antenna or antenna group whose interference power is lower than a second threshold value.

5. The wireless base station according to claim 1, wherein

the beam pattern determination unit includes a second beam pattern determination unit which changes the transmission power of the antenna or antenna group, in accordance with the received power of the transmission signal from the terminal by the antenna or antenna group, and

the second beam pattern determination unit increments the transmission power of the antenna or antenna group with high received power, and decrements the transmission power of the antenna or antenna group with low received power, in accordance with the received power of the transmission signal from the terminal by the antenna or antenna group.

6. The wireless base station according to claim 5, wherein

the second beam pattern determination unit estimates number of antennas necessary for the terminal based on requirement communication information of the terminal, increments the transmission power up to the estimated number of antennas, and decrements the transmission power of and following the estimated number of antennas, in order from the antenna or antenna group with the high received power.

7. The wireless base station according to claim 1, wherein the wireless base station communicates with the terminal in a plurality of frequency bands, and

the beam pattern determination unit adjusts the transmission power of each antenna in the plurality of frequency bands.

8. A wireless communication system including a wireless base station that assigns an individual wireless resource in a frame using a plurality of frequency bands to a terminal located in a belonging cell area, and that transmits and receives data to and from the terminal using the wireless resource, wherein

the wireless base station reports transmission power of an antenna or antenna group included in the wireless base station, location information, and a direction of the antenna or antenna group, in association with the plurality of frequency bands, to a neighbor wireless base station through a network.

9. The wireless communication system according to claim 8, wherein

information reported by the base station is limited to information regarding a part of the antenna or antenna group facing a direction of the neighbor base station to which the information is reported.