L-3 Services, Inc.

L-3 Communications Titan Corporation

James Covosso Francis

David Delaney McGann

David M Smith

John Gorton

Howard Glen Ebersman

Christopher Robert Brown

James Robert Tiffany

A computer estimates multiple angles of arrival of a target signal received by an array of commutated antenna elements. In one aspect, samples of a received target signal obtained from an array of communicated antenna elements and from an element in an array of reference antenna elements are processed to make maximum-likelihood-estimations of multiple angles of arrival at which signals are received by the array of commutated antenna elements; and a display is mapped over time and frequency of the estimations, with the angle of arrival for a particular sample being represented by a variable given display feature.

Estimation of multiple angles of arrival of signals received by an array of antenna elements

A method of deciding whether an observed received signal is a particular signal of interest (SOI) includes the steps of: providing a statistical model of the particular signal of interest and a statistical model of the environment when the particular signal of interest is not present, and processing the observed received signal in accordance with a decision rule that uses the provided statistical models to decide whether the observed received signal is the particular signal of interest. The decision rule is: where LLR is log likelihood ratio, P denotes a probability, a(y) and a(y) are functions of first and second attributes of the observed signal y in a sequential order that said attribute functions are presented for computation of LLR(y), and +&#x3bb; and &#x2212;&#x3bb; are real numbers, wherein the statistical model of the particular signal of interest includes functions of attributes that individually have a probability distribution function fwhen the observed received signal is the particular signal of interest such that()&#x3e;0,where fis a probability distribution function of the respective individual attribute when the observed received signal is not a signal of interest.

Deciding whether a received signal is a signal of interest

A method of communicating individual packets i of K bits includes permutation mapping of the packets, with each permuted packet being denoted by &#x3a0;(i), wherein &#x3a0;is a permutation on K letters that is unique for each packet transmission. Each permuted packet &#x3a0;(i) is modulated to provide a complex vector x(&#x3a0;(i)) for each packet. The packets are transmitted over a AWGN channel so each individual packet i is received as a variable of the vector x(&#x3a0;(i)) in a complex vector y=x(&#x3a0;(i))+v, wherein n represents the sequential number of the transmission attempt for a particular packet and vrepresents noise. This method enables the packets to be transmitted while using an improved ARQ routine that includes soft-combining decisions and a constant constellation with a constellation complexity greater than two bits/symbol to thereby significantly improve ARQ-routine performance over the current state of the art.

Permutation mapping for ARQ-processed transmissions

A parameter of interest of a signal, such as the angle of arrival of a target signal received by an antenna system having an array of antenna elements, is estimated by (a) obtaining disparate observations of the target signal received by the antenna system; (b) with a computer, processing the disparate observations of the target signal to determine a subset of a set of possible further obtained disparate observations of the target signal for processing to enable an optimal estimation of the angle of arrival of the target signal; (c) obtaining the subset of further disparate observations of the signal; and (d) processing the obtained subset of further obtained disparate observations to obtain the optimal estimate of the parameter of interest.

Adaptive optimization of estimation of the angle of arrival of a signal received by an array of antenna elements

A preferred estimate of a given parameter is made by processing a set of data points representing estimates of the given parameter, such as the angle of arrival of a target signal. The process includes the steps of: (a) obtaining a set of data points representing estimates of a given parameter; (b) using a computer to process said data points with an unsupervised clustering algorithm to select data points for use in making a preferred estimate of the given parameter; and (c) using the selected data points to make a preferred estimate of the given parameter.

Using statistical learning methods to fuse parameter estimates

The angle of arrival is estimated for a received signal received by an array of commutated antenna elements, wherein there is a temporal boundary at the instant of commutation between antenna elements. Samples of the signal received by the elements of the array are preprocessed to construct maximum-likelihood-estimates of the received signal for points in time that are immediately adjacent the temporal boundaries and thereby provide a preprocessed signal. A maximum-likelihood-estimation of the angle of arrival of the received signal is made for the array of commutated antenna elements by processing the preprocessed signal.

Estimating the angle of arrival of a signal received by an array of commutated antenna elements

In a system for determining the angle of arrival of a target signal received by an array of antenna elements, a pair of receivers simultaneously obtain observations of a received target signal from multiple elements of an array of antenna elements; and a computer processes the simultaneously obtained samples of the target signal to determine a maximum likelihood estimation (MLE) of the angle of arrival &#x3c6; of the target signal by using the following equation: &#x3c6;=argmaxRe(&#x3b1;*&#x3b2;). The value of &#x3b2; is determined in accordance with whether the target signal is known or unknown. When the target signal is unknown, the computer also processes the simultaneously obtained samples of the target signal to estimate the bandwidth of the received target signal by using binary hypotheses and a generalized log likelihood ratio test (GLLRT) or by using multiple hypotheses and pair-wise generalized log likelihood ratio tests. The value of a bandwidth constraint M that is associated with the estimated bandwidth is used to derive the value of &#x3b2; that is used to determine the MLE of &#x3c6;.

Determining the angle of arrival of a target signal received by an array of antenna elements

In a system for determining the angle of arrival of a target signal received by an array of antenna elements, a receiver obtains observations of a received target signal from an array of antenna elements; and a computer processes the obtained observations of the target signal with estimates of a target signal for different angles of arrival of a target signal received by the array of antenna elements to determine that the angle of arrival of the target signal is an angle of arrival at which dissimilarity between the observations of target signal and the estimates of the target signal for the different angles of arrival is minimized.

Sample vectors of a signal received simultaneously by an array of antennas are processed to estimate a weight for each sample vector that maximizes the energy of the individual sample vector that resulted from propagation of the signal from a known source and/or minimizes the energy of the sample vector that resulted from interference with propagation of the signal from the known source. Each sample vector is combined with the weight that is estimated for the respective sample vector to provide a plurality of weighted sample vectors. The plurality of weighted sample vectors are summed to provide a resultant weighted sample vector for the received signal. The weight for each sample vector is estimated by processing the sample vector in accordance with the expression: where=1 and 0&#x3c;p&#x2266;&#x221e;. The processing of the sample vector to estimate the weight, includes a step of calculating a pseudoinverse (ZX*Y). The pseudoinverse is calculated by a simplified method.

Weighting a signal received by an antenna array to enhance the signal and suppress interference

In a radio network that includes at least one base station and at least one remote station, signals are modulated for transmission from the remote stations by embedding known information throughout the signal in a predetermined pattern and a group of sample vectors of a signal received by at least one base station of the network are collected and processed to detect a said received signal that resulted from propagation of a signal from a remote station of the network. The group of sample vectors is collected from (a) signals that are received by more than one base station of the network; and/or (b) signals that are received simultaneously at different frequencies by at least one base station of the network.

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Honeoye Falls, NY, United States of America

James Covosso Francis