US 6,188,915 B1Granted

Bootstrapped, piecewise-asymptotic directivity pattern control mechanism setting weighting coefficients of phased array antenna

AssigneeHarris Corporation

InventorsGayle Patrick Martin, Steven D. Halford, John C. Henry, III

Life of this patent

Estimating the term…

Loading patent…

Abstract

Weighting coefficients for a phased array antenna are iteratively refined to optimal values by a ‘bootstrapped’ process that starts with a coarse set of weighting coefficients, to which received signals are subjected, to produce a first set of signal estimates. These estimates and the received signals are iteratively processed a prescribed number of times to refine the weighting coefficients, such that the gain and/or nulls of antenna's directivity pattern will maximize the signal to noise ratio. Such improved functionality is particularly useful in association with the phased array antenna of a base station of a time division multiple access (TDMA) cellular communication system, where it is necessary to cancel interference from co-channel users located in cells adjacent to the cell containing a desired user and the base station.

Claims39

Dependent claims

A method of processing signals representative of outputs of antenna elements of a phased array antenna to derive amplitude and phase weighting coefficients, through which signal coupling paths of said antenna elements are controllably weighted to control a directivity pattern of said phased array antenna, said method comprising the steps of:

(a) providing values of said weighting coefficients;
(b) modifying said signals representative of outputs of said antenna elements in accordance with said values of said weighting coefficients provided in step (a);
(c) generating estimates of information signal contents of signals representative of outputs of said antenna elements as modified in step (b);
and
(d) iteratively adjusting said signals representative of outputs of said antenna elements by
(d1) subjecting said signals representative of outputs of said antenna elements and estimates of information signal contents of signals representative of outputs of said antenna elements to a prescribed signal processing operator, which combines estimates of said information signal contents of signals representative of outputs of said antenna elements and signals representative of information signal contents and noise signal contents of outputs of said antenna elements to produce respective sets of signal and noise covariances, and generates improved values of said weighting coefficients in accordance with said respective sets of signal and noise covariances, and
(d2) adjusting said signals representative of outputs of said antenna elements in accordance with said improved values of said weighting coefficients to produce improved signal outputs of said antenna elements, and
(d3) iteratively repeating steps (d1) and (d2) a number of times N, where N is greater than or equal to zero.

5 more elements

(a) providing values of said weighting coefficients;
(b) modifying said signals representative of outputs of said antenna elements in accordance with said values of said weighting coefficients provided in step (a);
(c) generating estimates of information signal contents of signals representative of outputs of said antenna elements as modified in step (b);
and
(d) iteratively adjusting said signals representative of outputs of said antenna elements by
(d1) subjecting said signals representative of outputs of said antenna elements and estimates of information signal contents of signals representative of outputs of said antenna elements to a prescribed signal processing operator, to derive improved values of said weighting coefficients,
(d2) adjusting said signals representative of outputs of said antenna elements in accordance with said improved values of said weighting coefficients to produce improved signal outputs of said antenna elements, and
(d3) iteratively repeating steps (d1) and (d2) a number of times N, where N is greater than or equal to zero, and wherein
said phased array antenna is installed at a cell base station of a multi-cell, time division multiple access (TDMA) cellular communication system, and has its directivity pattern adaptively modified in steps (a)-(d) so as to form a beam whose gain and/or nulls are defined so as to maximize the signal to noise ratio in the presence of co-channel users whose communication time slots overlap a communication time slot of a desired user.

6 more elements

For use with a phased array antenna having a plurality of antenna elements, signal coupling paths of which are controllably weighted by amplitude and phase weighting coefficients to control a beam pattern of said phased array antenna, a method of processing signals representative of outputs of said antenna elements, to derive said weighting coefficients, said method comprising the steps of:

(a) generating initial values of said weighting coefficients;
(b) adjusting said signals representative of outputs of said antenna elements in accordance with said initial values of said weighting coefficients generated in step (a);
(c) generating initial estimates of information signal contents of signals representative of outputs of said antenna elements as adjusted in step (b);
(d) subjecting said signals representative of outputs of said antenna elements and said initial estimates of information signal contents of signals representative of outputs of said antenna elements generated in step (c) to a prescribed signal processing operator, which combines estimates of said information signal contents of signals representative of outputs of said antenna elements and signals representative of information signal contents and noise signal contents of outputs of said antenna elements to produce respective sets of signal and noise covariances, and generates improved values of said weighting coefficients in accordance with said respective sets of signal and noise covariances;
and
(e) adjusting said signals representative of outputs of said antenna elements in accordance with said improved values of said weighting coefficients generated in step (d) to produce improved signal outputs of said antenna elements.

3 more elements

A time division multiple access (TDMA) cellular communication system comprising:

a plurality of cells, that are dispersed relative to a cell in which a desired user conducts communications with a base station in said cell, and wherein said dispersed cells contain co-channel users which may transmit during time slots that overlap a desired user's time slot used for communications between said desired user and said base station;
and
a base station signal processing arrangement for reducing interference of communications between said desired user and said base station, by transmissions from said co-channel users in said dispersed cells during said time slot, said base station signal processing arrangement including:
a phased array antenna, and
a signal processor, coupled to said phased array antenna and being programmed to process signals received from said co-channel users, and adaptively controlling values of amplitude and phase weighting coefficients, through which signal coupling paths of said antenna elements are controllably weighted to control a directivity pattern of said phased array antenna in a manner that maximizes the signal to noise ratio in the presence of co-channel users whose communication time slots overlap a communication time slot of said desired user by performing the steps of:
(a) providing values of said weighting coefficients;
(b) modifying said signals representative of outputs of said antenna elements in accordance with said values of said weighting coefficients provided in step (a);
(c) generating estimates of information signal contents of signals representative of outputs of said antenna elements as modified in step (b);
and
(d) iteratively adjusting said signals representative of outputs of said antenna elements by
(d1) subjecting said signals representative of outputs of said antenna elements and estimates of information signal contents of signals representative of outputs of said antenna elements to a prescribed signal processing operator to derive improved values of said weighting coefficients, and
(d2) adjusting said signals representative of outputs of said antenna elements in accordance with said improved values of said weighting coefficients to produce improved signal outputs of said antenna elements, and
(d3) iteratively repeating steps (d1) and (d2) a number of times N, where N is greater than or equal to zero.

10 more elements

Dependencies are inferred from the claim text.