Wireless communication system

• US 20060217158A1
• Filed: 02/09/2006
• Published: 09/28/2006
• Est. Priority Date: 03/22/2005
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kuwahara, Mikio, Fujishima, Kenzaburo, Uwano, Koki, Taira, Masanori
• Granted Patent: US 7,639,984 B2
• Time in Patent Office: Days
• US Class Current: 455/562.100
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04W 16/26 Cell enhancers or enhancement, e.g. for tunnels, building shadow
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 28/10 Flow control between communication endpoints
• CPC Class Codes: H04W 64/006 with additional information processing, e.g. for direction or speed determination

Abstract

A wireless communication which suppresses radio interference between wireless base stations and improves the channel efficiency is implemented. In the wireless communication system including a central base station, a plurality of remote base stations having a direction-variable antenna, and a plurality of mobile stations to communicate with the remote base stations, the central base station performs centralized management of radio-wave beam patterns to be sent to the plurality of mobile stations which will communicate with remote base stations and performs packet scheduling of the mobile stations in such a manner that radio waves sent from the remote base stations will not cause strong interference at the mobile stations.

Claims

1. A wireless communication system in which a central base station and a plurality of remote base stations are connected by a communication medium such as a fiber-optic cable, and the remote base station performs wireless communication with a plurality of mobile stations;

the remote base station comprising a direction-variable antenna of which directivity varies with an electric signal supplied to a plurality of antenna elements; and

the central base station holding area information of a beam pattern of the remote base station serving each mobile station and combination information of beam patterns causing interference among the remote base stations, referencing the combination information in accordance with allocation priority information of the mobile station, and performing packet scheduling of the mobile station so that interference of radio waves sent from the remote base stations to the mobile stations can be suppressed.

2. A wireless communication system according to claim 1, wherein the central base station holds electric signals to be supplied to the direction-variable antenna as a plurality of beam patterns, and the directivity is changed by switching the beam pattern as selected in accordance with the position of the mobile station.

3. A wireless communication system according to claim 2, wherein the central base station estimates the position of the mobile station by predicting the direction in which radio waves come from the mobile station, and determines the beam pattern to be sent to the mobile station.

4. A wireless communication system according to claim 2, wherein each mobile station receives radio waves of all beam patterns from the remote base stations and notifies the central base station of a beam received with good quality, and the central base station determines the beam pattern to be sent to the mobile station.

5. A wireless communication system according to claim 3, wherein the central base station performs centralized management of the beam patterns to be sent to all the mobile stations.

6. A wireless communication system according to claim 1, wherein the central base station comprises:

a first table which stores an area of a remote base station in which each mobile station is placed, and the allocation priority level of the mobile station;

a second table which stores an area of a remote base station causing interference with a certain area of a certain remote base station; and

a selection block for selecting such a mobile station that a transmitted beam will not cause strong interference, in accordance with the priority levels of the mobile stations stored in the first table and with reference to the second table;

wherein a combination of mobile stations are determined so that interference will not occur between radio waves sent by the remote base stations.

7. A wireless communication system according to claim 1, wherein each mobile station measures radio waves sent from the remote base station, determines a beam pattern causing interference, and notifies the central base station of interference area information;

and

the central base station specifies the combination information of beam patterns causing interference, in accordance with the notified interference area information, and determines such a combination of mobile stations that radio waves sent from the remote base stations will not cause interference, in accordance with the specified combination information.

8. A wireless communication system according to claim 7, wherein beam patterns of radio waves to be checked for interference are selected in accordance with the communicating position of each mobile station, in the radio wave measurement of the mobile station.

9. A wireless communication system according to claim 4, wherein the central base station performs centralized management of the beam patterns to be sent to all the mobile stations.