LINEAR COMBINATIONS OF TRANSMIT SIGNALS BY A RECEIVER

• US 20170338874A1
• Filed: 04/03/2017
• Published: 11/23/2017
• Est. Priority Date: 04/02/2016
• Status: Active Grant

• Current Assignee: University of Notre DAME Du Lac
• Original Assignee: University of Notre DAME Du Lac
• Inventors: Pratt, Thomas G., Kossler, Robert Daniel, Mueller, Jeffrey G.
• Granted Patent: US 10,623,075 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 7/023 Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36
• CPC Class Codes: G01S 7/024 using polarisation effects in waveguides H01P1/165; for aerials H01Q, e.g. H01Q15/22, H01Q15/24, H01Q19/195
• CPC Class Codes: H04B 2001/0491 with frequency synthesizers, frequency converters or modulators
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0862 receiver computing weights based on information from the transmitter
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity

Abstract

A multi-port transmitter can synthesize and send a first plurality of transmit signals having a separability characteristic which permits them to be differentiated from one another. A receiver can then detect one or more receiver signals which include one or more combinations of received versions of the first plurality of transmit signals. The receiver may use the separability characteristic to determine the received versions of the first plurality of transmit signals from the one or more receiver signals. Then, the receiver may determine an estimated signal corresponding to the estimated receiver response to a second plurality of virtual transmit signals which comprise a combination of the first plurality of transmit signals. Determining the estimated signal may include forming a combination of the received versions of the first plurality of transmit signals.

Claims

1. A method comprising:

synthesizing a first plurality of transmit signals having a separability characteristic which permits them to be differentiated from one another;

transmitting the first plurality of transmit signals using a multi-port transmitter;

receiving one or more receiver signals using a receiver, the one or more receiver signals comprising one or more combinations of received versions of the first plurality of transmit signals;

using the separability characteristic to determine the received versions of the first plurality of transmit signals from the one or more receiver signals; and

determining, using the receiver, an estimated signal corresponding to the estimated receiver response to a second plurality of virtual transmit signals which comprise a combination of the first plurality of transmit signals, wherein determining the estimated signal comprises forming a combination of the received versions of the first plurality of transmit signals.

2. The method of claim 1, wherein the first plurality of transmit signals have one or more relative amplitude and phase differences which correspond to a first polarization state or a first beam state, and wherein the second plurality of virtual transmit signals are associated with a different second polarization state or a different second beam state.

3. The method of claim 1, wherein the first plurality of transmit signals are transmitted via a respective plurality of transmitter antenna elements, or wherein the first plurality of transmit signals are respectively transmitted as a plurality of beams each transmitted using multiple transmitter antenna elements, or wherein the first plurality of transmit signals are transmitted via a combination of beams and individual antenna elements.

4. The method of claim 1, wherein the one or more receiver signals comprise a single receiver signal received via a single receiver antenna element, or wherein the one or more receiver signals comprise a plurality of receiver signals received via a respective plurality of receiver antenna elements, or wherein the one or more receiver signals comprise a plurality of receiver signals which are respectively received as a plurality of beams each received using a plurality of receiver antenna elements.

5. The method of claim 1, wherein the combination comprises a linear combination.

6. The method of claim 5, wherein the linear combination comprises a complex weighted linear combination.

7. The method of claim 6, wherein forming the complex weighted linear combination comprises selecting complex weights which cause the estimated signal to satisfy a selected criterion.

8. The method of claim 7, wherein the criterion comprises:

that a signal power of the estimated signal is greater than that of one or more of the receiver signals;

that a signal power of the estimated signal is less than that of one or more of the receiver signals;

that the estimated signal has a selected polarization state or a selected polarization mode dispersion profile;

or

that the estimated signal has a selected coherence state or a selected coherence dispersion profile.

9. The method of claim 1, wherein forming the combination of the received versions of the first plurality of transmit signals is performed on a frequency sub-band-by-sub-band basis.

10. The method of claim 9, wherein different combining weights are used for different frequency sub-bands.

11. The method of claim 1, further comprising forming a combination of the receiver signals.

12. The method of claim 1, wherein the second plurality of virtual transmit signals comprise a complex weighted linear combination of the first plurality of transmit signals.

13. The method of claim 1, wherein the separability characteristic comprises time multiplexing, frequency multiplexing, code multiplexing, beam multiplexing, or eigenmode multiplexing.

14. The method of claim 1, wherein the first plurality of transmit signals are coherently synthesized and transmitted.

15. The method of claim 14, wherein the first plurality of transmit signals are synthesized from a common transmit waveform, the first plurality of transmit signals having one or more relative amplitude, phase, time delay, frequency offset, or transmission beam differences with respect to one another.

16. The method of claim 1, wherein the receiver signals are coherently received.

17. The method of claim 1, wherein the first plurality of transmit signals are transmitted using orthogonally-polarized antenna elements.

18. The method of claim 1, wherein the first plurality of transmit signals are transmitted using spatially-separated antenna elements.

19. The method of claim 1, wherein the receiver signals are received using orthogonally-polarized antenna elements.

20. The method of claim 1, wherein the receiver signals are received using spatially-separated antenna elements.

22. The system of claim 20, wherein the transmitter and the receiver are co-located.

21. A system comprising:

a multi-port transmitter configured to coherently transmit a first plurality of transmit signals having a separability characteristic which permits them to be differentiated from one another; and

a receiver configured to;

receive one or more receiver signals;

determine received versions of the first plurality of transmit signals from the one or more receiver signals using the separability characteristic; and

determine an estimated signal corresponding to the estimated receiver response to a second plurality of virtual transmit signals which comprise a combination of the first plurality of transmit signals, wherein determining the estimated signal comprises forming a combination of the received versions of the first plurality of transmit signals.

23. A receiver comprising:

one or more input ports to receive one or more receiver signals which include receiver responses to a first plurality of transmit signals from a transmitter, the first plurality of transmit signals having a separability characteristic which permits them to be differentiated from one another; and

a signal processor configured to;

determine received versions of the first plurality of transmit signals from the one or more receiver signals using the separability characteristic; and

determine an estimated signal corresponding to the estimated receiver response to a second plurality of virtual transmit signals which comprise a combination of the first plurality of transmit signals, wherein determining the estimated signal comprises forming a combination of the received versions of the first plurality of transmit signals.