Adaptive antenna unit for mobile terminal

• US 20030232633A1
• Filed: 06/04/2003
• Published: 12/18/2003
• Est. Priority Date: 06/05/2002
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Toda, Takeshi, Iida, Atsuo
• Granted Patent: US 6,917,337 B2
• Time in Patent Office: Days
• US Class Current: 455/575.7
• CPC Class Codes: H01Q 1/241 used in mobile communications, e.g. GSM H01Q1/247, H01Q1/248 take precedence
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays

Abstract

An adaptive antenna unit is adapted to a mobile terminal for making mobile communication and adaptively forms an antenna directivity in a direction of a base station which exchanges signals with the mobile terminal. The adaptive antenna unit is provided with an azimuth sensor to detect at least one of rotation, inclination and present position of the mobile terminal, a transmitter-receiver section to control the antenna directivity in a direction in which a reception characteristic improves based on reception signals received from a plurality of antenna elements forming the antenna directivity, and a mechanism for correcting the antenna directivity in the direction of the base station, based on the at least one of rotation, inclination and present position of the mobile terminal detected by the azimuth sensor.

Claims

1. An adaptive antenna unit which is adapted to a mobile terminal for making mobile communication and adaptively forms an antenna directivity in a direction of a base station which exchanges signals with the mobile terminal, comprising:

an azimuth sensor to detect at least one of rotation, inclination and present position of the mobile terminal;

a transmitter-receiver section to control the antenna directivity in a direction in which a reception characteristic improves based on reception signals received from a plurality of antenna elements forming the antenna directivity; and

means for correcting the antenna directivity in the direction of the base station, based on the at least one of rotation, inclination and present position of the mobile terminal detected by the azimuth sensor.

2. The adaptive antenna unit as claimed in claim 1, wherein:

the plurality of antenna elements are arranged to form the antenna directivity in a three-dimensional direction; and

further comprising;

means for controlling the antenna directivity in the three-dimensional direction with respect to the plurality of antenna elements.

3. The adaptive antenna unit as claimed in claim 1, wherein:

the azimuth sensor includes a sensor to detect a gravitational direction; and

further comprising;

means for correcting a direction of rotation or inclination of the mobile terminal based on the gravitational direction detected by the sensor.

4. The adaptive antenna unit as claimed in claim 1, wherein:

the azimuth sensor includes a global positioning system (GPS) to detect present position information related to a present position of the mobile terminal; and

further comprising;

means for detecting a direction of a closest base station, based on the present position information detected by the GPS and map information,

said map information being selected from a group consisting of map information prestored within the mobile terminal and map information notified from the base station.

5. The adaptive antenna unit as claimed in claim 1, wherein:

the plurality of antenna elements include parasitic antenna elements each terminated by a variable reactance element; and

further comprising;

means for controlling the antenna directivity by varying a reactance component of the variable reactance element of each of the parasitic antenna elements.

6. The adaptive antenna unit as claimed in claim 2, wherein the direction in which the antenna directivity is controlled based on the at least one of rotation, inclination and position of the mobile terminal detected by the azimuth sensor, and the direction in which the antenna directivity is controlled to improve the reception characteristic based on the reception signals received from the plurality of antenna elements, are of mutually different dimensions.

7. The adaptive antenna unit as claimed in claim 6, wherein the direction in which the antenna directivity is controlled based on the at least one of rotation, inclination and position of the mobile terminal detected by the azimuth sensor is perpendicular to a plane in which each of the plurality of antenna elements is arranged, and the direction in which the antenna directivity is controlled to improve the reception characteristic based on the reception signals received from the plurality of antenna elements is within the plane in which each of the plurality of antenna elements is arranged.

8. The adaptive antenna unit as claimed in claim 5, further comprising:

a transmitter-receiver radio frequency front end including a micro electro mechanical system (MEMS) variable capacitor forming the variable reactance element of each of the parasitic antenna elements.

9. The adaptive antenna unit as claimed in claim 1, wherein the antenna directivity is selected from a plurality of mutually different directivity patterns depending on a wave propagation environment.

10. The adaptive antenna unit as claimed in claim 1, wherein an initial antenna directivity at a start of a communication is set to an antenna directivity which is formed last in a standby state, when starting the communication from the standby state.

11. The adaptive antenna unit as claimed in claim 1, wherein the control of the antenna directivity based on the at least one of rotation, inclination and position of the mobile terminal detected by the azimuth sensor, and the control of the antenna directivity to improve the reception characteristic based on the reception signals received from the plurality of antenna elements are carried out alternately.

12. The adaptive antenna unit as claimed in claim 1, further comprising:

means for controlling the antenna directivity based on the at least one of rotation, inclination and position of the mobile terminal detected by the azimuth sensor with respect to a quick change in the antenna directivity, and controlling the antenna directivity to improve the reception characteristic based on the reception signals received from the plurality of antenna elements with respect to a gradual change in the antenna directivity.

13. The adaptive antenna unit as claimed in claim 5, wherein the parasitic antenna elements are stacked in a plurality of stages.

14. The adaptive antenna unit as claimed in claim 1, wherein the plurality of antenna elements are arranged at a pitch which is less than or equal to one wavelength.

15. A mobile terminal for making mobile communication with a base station by exchanging signals, comprising:

a plurality of antenna elements to adaptively form an antenna directivity in a direction of the base station;

an azimuth sensor to detect at least one of rotation, inclination and present position of the mobile terminal;

a transmitter-receiver section to control the antenna directivity in a direction in which a reception characteristic improves based on reception signals received from the plurality of antenna elements; and

means for correcting the antenna directivity in the direction of the base station, based on the at least one of rotation, inclination and present position of the mobile terminal detected by the azimuth sensor.

16. The mobile terminal as claimed in claim 15, wherein:

the plurality of antenna elements are arranged to form the antenna directivity in a three-dimensional direction; and

further comprising;

means for controlling the antenna directivity in the three-dimensional direction with respect to the plurality of antenna elements.

17. The mobile terminal as claimed in claim 15, wherein:

the azimuth sensor includes a sensor to detect a gravitational direction; and

further comprising;

means for correcting a direction of rotation or inclination of the mobile terminal based on the gravitational direction detected by the sensor.

18. The mobile terminal as claimed in claim 15, wherein:

the azimuth sensor includes a global positioning system (GPS) to detect present position information related to a present position of the mobile terminal; and

further comprising;

means for detecting a direction of a closest base station, based on the present position information detected by the GPS and map information,

said map information being selected from a group consisting of map information prestored within the mobile terminal and map information notified from the base station.

19. The mobile terminal as claimed in claim 15, wherein:

the plurality of antenna elements include parasitic antenna elements each terminated by a variable reactance element; and

further comprising;

means for controlling the antenna directivity by varying a reactance component of the variable reactance element of each of the parasitic antenna elements.