Adaptive antenna for controlling the weighting on a plurality of antenna elements

• US 7,340,277 B2
• Filed: 11/22/2001
• Issued: 03/04/2008
• Est. Priority Date: 11/30/2000
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Nakamura, Hiroshi
• Primary Examiner(s): Eng; George
• Assistant Examiner(s): PHAN, HUY Q
• Application Number:
  US10/432,865
• Publication Number:
  US 20040033818A1
• Time in Patent Office: 2,294 Days
• Field of Search: 455/456.1, 455/404.2, 455/25, 455/63.4, 455/67.16, 455/561, 455/562.1, 342/42, 342/46, 342/153, 342/357.12, 342/163, 342/461, 342/154, 342/357.07, 342/354, 342/357.17, 342/386
• US Class Current: 455/561
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
• 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: H04B 7/086 using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming

Abstract

An optical subscriber system according to the present invention has an adaptive antenna having a plurality of antenna elements, for controlling the weighting on the antenna elements thereby to radiate beams that are adapted to radio wave environments, a position estimator for estimating the position of a mobile unit, a beam combiner for weighting signals received from the mobile unit by the antenna elements and combining beams, and a weighting coefficient generator for correcting weighting coefficients adapted to radio wave environments, which give initial weights as weights to form nulls in bearings other than the mobile unit based on the position of the mobile unit which has been estimated by the position estimator, for thereby reducing a time required for convergence.

Claims

1. A mobile unit communication apparatus remote from a mobile unit comprising:

an adaptive antenna having a plurality of antenna elements to which weighting coefficients are applied to radiate beams that are adapted to radio wave environments;

a position estimator which performs position calculations for estimating a position to which said mobile unit will move based on transmitted signals which do not contain position information from said mobile unit received by said antenna;

a beam combiner for weighting said received signals and for combining beams; and

a weighting coefficient generator which reduces a time required for convergence of the position calculations,

wherein said weighting coefficient generator corrects weighting coefficients adapted to radio wave environments, which give initial weights to said received signals to form nulls in bearings other than said mobile unit based on the position of the mobile unit which has been estimated by said position estimator.

2. A mobile unit communication apparatus remote from a mobile unit according to claim 1, wherein said position estimator has a speed estimator supplied with said received signals, for estimating a speed of said mobile unit based on a phase shift from a reference value of a predetermined pilot signal component.

3. A mobile unit communication apparatus remote from a mobile unit according to claim 2, further comprising a weight corrector for correcting the weights of said received signals with estimated values of the speed at which said mobile unit moves and a direction in which said mobile unit moves.

4. A mobile unit communication system comprising a mobile unit communication apparatus remote from a mobile unit according to claim 3 wherein said position estimator has a distance predictor, a transmitted electric power controller for controlling transmitted electric power depending on a predicted distance, and a transmitted electric power controller mounted on a mobile unit for transmitting a predicted distance to the mobile unit and controlling transmitted electric power of the mobile unit depending on the predicted distance.

5. A mobile unit communication system comprising a mobile unit communication apparatus remote from a mobile unit according to claim 2 wherein said position estimator has a distance predictor, a transmitted electric power controller for controlling transmitted electric power depending on a predicted distance, and a transmitted electric power controller mounted on a mobile unit for transmitting a predicted distance to the mobile unit and controlling transmitted electric power of the mobile unit depending on the predicted distance.

6. A mobile unit communication apparatus remote from a mobile unit according to claim 1, wherein said position estimator has a speed estimator for estimating a speed of said mobile unit based on a change in a pilot signal output from said beam combiner.

7. A mobile unit communication apparatus remote from a mobile unit according to claim 6, further comprising a weight corrector for correcting the weights of said received signals with estimated values of the speed at which said mobile unit moves and a direction in which said mobile unit moves.

8. A mobile unit communication system comprising a mobile unit communication apparatus remote from a mobile unit according to claim 7 wherein said position estimator has a distance predictor, a transmitted electric power controller for controlling transmitted electric power depending on a predicted distance, and a transmitted electric power controller mounted on a mobile unit for transmitting a predicted distance to the mobile unit and controlling transmitted electric power of the mobile unit depending on the predicted distance.

9. A mobile unit communication system comprising a mobile unit communication apparatus remote from a mobile unit according to claim 6 wherein said position estimator has a distance predictor, a transmitted electric power controller for controlling transmitted electric power depending on a predicted distance, and a transmitted electric power controller mounted on a mobile unit for transmitting a predicted distance to the mobile unit and controlling transmitted electric power of the mobile unit depending on the predicted distance.

10. A mobile unit communication apparatus remote from a mobile unit according to claim 1, further comprising a weight corrector for correcting the weights of said received signals with estimated values of a speed at which said mobile unit moves and a direction in which said mobile unit moves.

11. A mobile unit communication system comprising a mobile unit communication apparatus remote from a mobile unit according to claim 10 wherein said position estimator has a distance predictor, a transmitted electric power controller for controlling transmitted electric power depending on a predicted distance, and a transmitted electric power controller mounted on a mobile unit for transmitting a predicted distance to the mobile unit and controlling transmitted electric power of the mobile unit depending on the predicted distance.

12. A mobile unit communication system comprising a mobile unit communication apparatus remote from a mobile unit according to claim 1 wherein said position estimator has a distance predictor, a transmitted electric power controller for controlling transmitted electric power depending on a predicted distance, and a transmitted electric power controller mounted on a mobile unit for transmitting a predicted distance to the mobile unit and controlling transmitted electric power of the mobile unit depending on the predicted distance.