Dynamic equalization systems and methods for use with a receiver for a multipath channel

• US 8,804,808 B1
• Filed: 01/14/2014
• Issued: 08/12/2014
• Est. Priority Date: 01/14/2014
• Status: Active Grant

• Current Assignee: Aerospace Corporation
• Original Assignee: Aerospace Corporation
• Inventors: Dybdal, Robert B., Clark, Christopher J., Lorenzelli, Flavio
• Primary Examiner(s): Ahn, Sam K
• Assistant Examiner(s): Ali, Shawkat M
• Application Number:
  US14/154,968
• Time in Patent Office: 210 Days
• Field of Search: 370/210, 370/291, 375229-236, 375/316, 375/340, 375/343, 375/350
• US Class Current: 375/232
• CPC Class Codes: H04L 2025/03522 Frequency domain
• CPC Class Codes: H04L 2027/0038 using an equaliser
• CPC Class Codes: H04L 2027/0055 single phase
• CPC Class Codes: H04L 2027/0095 in a preamble or similar structure
• CPC Class Codes: H04L 25/03019 adaptive, i.e. capable of adjustment during data reception
• CPC Class Codes: H04L 27/01 Equalisers baseband equalizers at the transmitter end H04L25/03343; in analogue transmission systems H04B3/04, H04B7/005
• CPC Class Codes: H04L 27/206 using a pair of orthogonal carriers, e.g. quadrature carriers

Abstract

A dynamic equalization system and method for use with a receiver is provided. The receiver may include an antenna for receiving a signal having multipath signal components and a digitizer for obtaining and digitizing the received signal and multipath signal components. The digitized signal segment and multipath signal components may be discretized into signal segments of length n. Channel parameters of each of the discrete signal segments may be analyzed and locked to, and a time-domain representation of the analyzed channel parameters may be output. Each time-domain representation may be Fourier transformed into a frequency-domain representation, based upon which equalization parameters to equalize the multipath signal components for each of the analyzed channel parameters may be determined. The equalization parameters may be applied to corresponding signal segments of the digitized signal and multipath signal components so as to equalize the multipath signal components.

Claims

1. A dynamic equalization system for use with a receiver, the receiver comprising an antenna configured to receive a signal distorted by multipath signal components and a digitizer configured to obtain and digitize the signal and multipath signal components received by the antenna, the dynamic equalization system comprising:

an equalization estimator configured to receive the digitized signal and multipath signal components from the digitizer, the equalization estimator comprising;

acquisition circuitry configured to sequentially output discrete signal segments of length n of the digitized signal and multipath signal components;

channel parameter loop circuitry configured to sequentially analyze and lock to channel parameters including phase, delay, and carrier frequency of the corresponding signal segment, and to output a time-domain representation of each of the analyzed channel parameters for the corresponding signal segment;

Fourier transform circuitry configured to sequentially Fourier transform each time-domain representation into a frequency-domain representation for each of the analyzed channel parameters for the corresponding discrete signal segment, and to output the frequency-domain representation; and

an equalization processor configured to determine and output equalization parameters to equalize the multipath signal components for each of the analyzed channel parameters based on the frequency-domain representations;

an equalizer configured to sequentially receive the discrete signal segments of the digitized signal and multipath signal components from the acquisition circuitry, to sequentially receive the equalization parameters from the equalization processor, to sequentially apply the equalization parameters to the corresponding signal segments so as to equalize the multipath signal components, and to output the equalized signal segments; and

alignment circuitry configured to sequentially receive the corresponding equalized signal segments from the equalizer and the analyzed channel parameters for an earliest-in-time signal component from the equalization processor and to align the earliest-in-time signal component with the equalized multipath signal components within the equalized signal segments based thereon.

2. The dynamic equalization system of claim 1, wherein the equalization processor further is configured to sequentially determine and output the analyzed channel parameters for the earliest-in-time signal component corresponding to the signal based on the frequency-domain representations.

3. The dynamic equalization system of claim 2, wherein the equalization processor is configured to determine the analyzed channel parameters for the earliest-in-time signal for a signal segment based on a position or amplitude of those parameters in the frequency-domain representation for that signal segment.

4. The dynamic equalization system of claim 1, further comprising demodulation circuitry configured to sequentially demodulate the aligned, equalized signal segments so as to obtain a time-domain representation corresponding to the signal.

5. The dynamic equalization system of claim 1, wherein the equalization processor is configured to determine the equalization parameters for each of the analyzed channel parameters of a signal segment by calculating a filter that equalizes the multipath signal components for each of the analyzed channel parameters in that signal segment.

6. The dynamic equalization system of claim 5, wherein the equalizer is configured to apply the filter to the signal segment.

7. The dynamic equalization system of claim 1, wherein the channel parameter loop circuitry is configured to analyze and lock to the channel parameters based on a priori known information about the signal.

8. The dynamic equalization system of claim 1, wherein the signal comprises a sequence of blocks each having a preamble and data, and wherein n is equal to the length of each of the blocks.

9. A dynamic equalization method for use with a receiver comprising an antenna configured to receive a signal having multipath signal components and a digitizer configured to obtain and digitize the signal and multipath signal components received by the antenna, the method comprising:

receiving the digitized signal segment and multipath signal components from the digitizer, and sequentially outputting discrete signal segments of length n of the digitized signal and multipath signal components;

sequentially analyzing and locking to channel parameters including phase, delay, and carrier frequency of the discrete signal segments, and outputting a time-domain representation of the analyzed channel parameters for each signal segment;

sequentially Fourier transforming each of the time-domain representations into a frequency-domain representation;

based on the frequency-domain representations, sequentially determining equalization parameter to equalize the multipath signal components for each of the analyzed channel parameters;

sequentially applying the equalization parameters to corresponding signal segments of the digitized signal and multipath signal components so as to equalize the multipath signal components; and

sequentially aligning an earliest-in-time signal component with equalized multipath signal components based on the analyzed channel parameters for the earliest-in-time signal component.

10. The dynamic equalization method of claim 9, further comprising, based on the frequency-domain representations, sequentially determining the analyzed channel parameters for the earliest-in-time signal component channel parameters corresponding to the signal.

11. The dynamic equalization method of claim 10, wherein the analyzed channel parameters for the earliest-in-time signal for a signal segment are determined based on a position or amplitude of those parameters in the frequency-domain representation for that signal segment.

12. The dynamic equalization method of claim 9, further comprising sequentially demodulating the aligned, equalized signal segments so as to obtain a time-domain representation corresponding to the signal.

13. The dynamic equalization method of claim 9, wherein the equalization parameters for each of the analyzed channel parameters of a signal segment are determined by calculating a filter that equalizes the multipath signal components for each of the analyzed channel parameters in that signal segment.

14. The dynamic equalization method of claim 13, wherein applying the equalization parameters to the signal segment comprises applying the filter to the signal segment.

15. The dynamic equalization method of claim 9, wherein the channel parameters are analyzed and locked to based on a priori known information about the signal.

16. The dynamic equalization method of claim 9, wherein the signal comprises a sequence of blocks each having a preamble and data, and wherein n is equal to the length of each of the blocks.