US6930637B2 — Method and apparatus for high resolution tracking…

Claim 1

Independent Claim 134 words

A method of tracking a selected radio-frequency signal in a multiple access communication system, comprising the steps of: determining an estimated direction of arrival of a signal received at an antenna location; demodulating a received signal, from the estimated direction of arrival, into a digital base-band signal; descrambling the digital base-band signal; separating a selected signal from co-channel interference in the descrambled signal; tracking the direction of arrival of the selected signal by performing a sequence of steps comprising: measuring a summation beam at the estimated direction of arrival; measuring a difference beam at the estimated direction of arrival; comparing the summation and difference beams to derive an angular offset; updating the direction of arrival by applying the angular offset to the estimated direction of arrival; and repeating the measuring, comparing, and updating steps.

Claim 2

Independent Claim 134 words

A method of tracking a selected radio-frequency signal in a multiple access communication system, comprising the steps of: determining an estimated direction of arrival of a signal received at an antenna location; demodulating a received signal, from the estimated direction of arrival, into a digital base-band signal; descrambling the digital base-band signal; separating a selected signal from co-channel interference in the descrambled signal; tracking the direction of arrival of the selected signal by performing a sequence of steps comprising: measuring a summation beam at the estimated direction of arrival; measuring a difference beam at the estimated direction of arrival; comparing the summation and difference beams to derive an angular offset; updating the direction of arrival by applying the angular offset to the estimated direction of arrival; and repeating the measuring, comparing, and updating steps.

Claim 3

Dependent Claim 35 words

The method of claim 1 , wherein the step of determining an estimated direction of arrival comprises determining the orientation of a fixed location from which the signal is transmitted relative to the antenna location.

Claim 4

Dependent Claim 28 words

The method of claim 1 , wherein the step of determining an estimated direction of arrival comprises: performing fixed-beam searching over a sector extending from the antenna location.

Claim 5

Dependent Claim 21 words

The method of claim 3 , wherein the step of performing fixed-beam searching is performed substantially continuously as a background process.

Claim 6

Dependent Claim 43 words

The method of claim 4 , wherein the step of performing fixed-beam searching comprises: receiving signals at a plurality of antennae at the antenna location; performing a spatial transform of the received signals at the plurality of antennae to derive a weight vector.

Claim 7

Dependent Claim 94 words

The method of claim 5 , wherein the step of measuring the summation beam at the estimated direction of arrival comprises summing signals from at least some of the plurality of antennae using the weight vector; wherein the step of measuring the difference beam at the estimated direction of arrival comprises summing signals from at least some of the plurality of antennae in a first half of an antenna array with opposite-phase signals from at least some of the plurality of antennae in a second half of the antenna array, using the weight vector.

Claim 8

Dependent Claim 21 words

The method of claim 6 , wherein the first and second halves of the antenna are first and second azimuth halves.

Claim 9

Dependent Claim 51 words

The method of claim 7 , further comprising: summing signals from at least some of the plurality of antennae in a top half of the antennal array with opposite-phase signals from at least some of the plurality of antennae in a bottom half of the antenna array, using the weight vector.

Claim 10

Dependent Claim 26 words

The method of claim 1 , wherein the signal comprises a code-division-multiple-access (CDMA) encoded signal; and wherein the separating step comprises despreading the CDMA encoded signal.

Claim 11

Dependent Claim 21 words

The method of claim 9 , further comprising: prior to the tracking step, applying a match filter to the received signal.

Claim 12

Dependent Claim 26 words

The method of claim 1 , wherein the signal comprises a time-division-multiple-access (TDMA) encoded signal; and wherein the separating step comprises deinterleaving the TDMA encoded signal.

Claim 13

Dependent Claim 37 words

The method of claim 11 , further comprising: prior to the tracking step, applying a match filter to the received signal; and also prior to the tracking step, applying a delay to the received signal for synchronization.

Claim 14

Dependent Claim 130 words

A base station system for multiple access communication, comprising: an antenna array; a plurality of radio frequency demodulators for demodulating signals received at the antenna array into spatial samples; a user processing element for separating signals for a selected user from received signals from other users; and a mono-pulse beam forming processor, comprising: a summing beam former, for generating a summation signal from the plurality of spatial samples for the selected user and a weighting vector; a difference beam former, for generating a difference signal from the plurality of spatial samples and a weighting vector; a channel estimator, for generating an output signal corresponding to the summation signal; and circuitry for generating an angle estimation from the summation and difference signals and adjusting weighting vectors responsive to the angle estimation.

Claim 15

Dependent Claim 130 words

A base station system for multiple access communication, comprising: an antenna array; a plurality of radio frequency demodulators for demodulating signals received at the antenna array into spatial samples; a user processing element for separating signals for a selected user from received signals from other users; and a mono-pulse beam forming processor, comprising: a summing beam former, for generating a summation signal from the plurality of spatial samples for the selected user and a weighting vector; a difference beam former, for generating a difference signal from the plurality of spatial samples and a weighting vector; a channel estimator, for generating an output signal corresponding to the summation signal; and circuitry for generating an angle estimation from the summation and difference signals and adjusting weighting vectors responsive to the angle estimation.

Claim 16

Dependent Claim 79 words

The system of claim 13 , further comprising: a spatial transform processor, for transforming the plurality of spatial samples into a plurality of beam signals for a plurality of users; a plurality of user processing elements for determining a plurality of magnitudes of spatial samples corresponding to each of the plurality of beam signals; and a plurality of detectors for detecting the beam signal having the highest magnitude, the weighting vectors corresponding to ordered magnitudes of the beam signals.

Claim 17

Dependent Claim 16 words

The system of claim 13 , wherein the antenna array is a linear array of antennae.

Claim 18

Dependent Claim 16 words

The system of claim 13 , wherein the antenna array is a two-dimensional array of antennae.

Claim 19

Dependent Claim 36 words

The system of claim 13 , wherein the plurality of radio frequency demodulators demodulate code-division-multiple-access (CDMA) signals received at the antenna array; and wherein the user processing element separates signals by despreading the received CDMA signals.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2008-08-15	2009-02-14	2009-08-16	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2012-08-15	2013-02-14	2013-08-16	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2016-08-15	2017-02-14	2017-08-16	$7700.00	Window Closed / Lapsed

Method and apparatus for high resolution tracking via mono-pulse beam-forming in a communication system

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