Beamforming and interference cancellation system using general purpose filter architecture

• US 6,317,467 B1
• Filed: 06/14/2000
• Issued: 11/13/2001
• Est. Priority Date: 06/14/2000
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Baker, Robert M., Freeman, Stephen, Cox, Lloyd C., Nunez, Luis R., Krzemien, Cynthia R., Gramlich, Gary A., Neary, Brian P., Krim, Jordan A.
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): PHU, PHUONG M
• Application Number:
  US09/593,480
• Time in Patent Office: 517 Days
• Field of Search: 375/267, 375/260, 375/259, 455/226.2, 455/226.1, 455/562, 455/226.3, 455/25, 342/378, 342/379, 342/380, 342/382, 342/383, 342/384
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0617 for beam forming

Abstract

A beamforming system including a multiplier stage for providing a plurality of steered signal terms, each term being a product of an input signal term and a steering signal term. A filter multiplies the steered signal terms by a plurality of respective filter weights to provide a plurality of weighted products. The weighted products are summed to provide an output beam directionally responsive to the steering signal. A microprocessor provides the steering signal terms and the filter weights in response to the input signal and/or user input. In the preferred embodiment, the filter is a reconfigurable, general purpose matched filter configured to multiply a plurality of delayed representations of a respective one of the steered signal terms by a plurality of the weights to provide a plurality of intermediate weighted product terms. The filter further includes a summing circuit for accumulating the intermediate weighted product terms to provide a respective one of the plurality of weighted products. The inventive beamforming system cancels unwanted interference, while forming a beam to allow a desired signal to be received with a maximum signal-to-interference-plus-noise ratio (SINR). Through a data-capture RAM, the system allows interference samples to be collected and passed to a microprocessor to calculate the optimum filter weights. The received beam may be steered to any desired direction to form an optimal space-time adaptive matched filter.

Claims

1. A beamforming system comprising:

multiplier means for providing a plurality of steered signal terms, each term being a product of an input signal term and a steering signal term;

filter means for multiplying said steered signal terms by a plurality of respective filter weights to provide a plurality of weighted products;

means for summing said plurality of weighted products to provide an output beam directionally responsive to said steering signal; and

control means for providing said steering signal terms and said filter weights in response to said input signal and/or user input.

2. The invention of claim 1 wherein said multiplier means includes a first plurality of multipliers, each multiplier configured to multiply one of said input signal terms with a respective one of said steering signal terms to provide a respective one of said steering signal terms.

3. The invention of claim 2 wherein said filter means is a reconfigurable filter.

4. The invention of claim 3 wherein said reconfigurable filter is a general purpose filter.

5. The invention of claim 4 wherein said general purpose filter includes means for multiplying a plurality of delayed representations of a respective one of said steered signal terms by a plurality of said weights to provide a plurality of intermediate weighted product terms and means for accommodating said intermediate weighted product terms to provide a respective one of said plurality of weighted products.

6. The invention of claim 5 wherein said general purpose filter is a matched filter.

7. The invention of claim 6 wherein said general purpose filter includes a plurality of channels.

8. The invention of claim 7 wherein each channel includes a plurality of multipliers and delay elements configured to provide said intermediates weighted product terms.

9. The invention of claim 5 wherein said general purpose filter further includes a plurality of multipliers.

10. A digital receiver comprising:

receiver means for providing a plurality of digital received signal terms;

multiplier means for providing a plurality of steered signal terms, each term being a product of an received signal term and a steering signal term, said multiplier means including a first plurality of multipliers, each multiplier configured to multiply one of said received signal terms with a respective one of said steering signal terms to provide a respective one of said steered signal terms;

a reconfigurable filter for multiplying said steered signal terms by a plurality of respective filter weights to provide a plurality of weighted products, said filter including means for multiplying a plurality of delayed representations of a respective one of said steered signal terms by a plurality of said weights to provide a plurality of intermediate weighted product terms and means for accumulating said intermediate weighted product terms to provide a respective one of said plurality of weighted products;

means for summing said plurality of weighted products to provide an output beam directionally responsive to said steering signal; and

control means for providing said steering signal terms and said filter weights in response to said received signal terms and/or user input.

11. The invention of claim 10 wherein said filter includes a plurality of channels.

12. The invention of claim 11 wherein each channel includes a plurality of multipliers and delay elements configured to provide said intermediate weighted product terms.

13. The invention of claim 10 wherein said filter further includes a plurality of multipliers.

14. A beamforming method comprising the steps of:

providing a plurality of steered signal terms, each term being a product of an input signal term and a steering signal term;

multiplying said steered signal terms by a plurality of respective filter weights to provide a plurality of weighted products;

summing said plurality of weighted products to provide an output beam directionally responsive to said steering signal; and

providing said steering signal terms and said filter weights in response to said input signal and/or user input.