Description:Please see the attachments , Claims:Please see the attachments

We Claim:
1. A method of reducing interference at a wireless station
comprising a multi-element antenna array, the method comprising:
5 receiving interference and at least a first wanted signal comprising subcarriers at the multi-element antenna array;
forming a first wanted signal beam to receive the first wanted signal;
receiving, using the first wanted signal beam, a first sub-carrier and at
least a second sub-carrier of the first wanted signal, each having known
10 transmitted modulation;
generating a first linear combination, the first linear combination being a
combination of the received first sub-carrier and at least the received second
sub-carrier of the first wanted signal, the first linear combination using a first
linear relationship between subcarriers, the first linear relationship being
15 determined to reduce a component of the wanted signal in the first linear
combination;
forming a first orthogonal beam orthogonal to the first wanted signal
beam;
generating a second linear combination, the second linear combination
20 being a combination of a first subcarrier received in the first orthogonal beam
corresponding in frequency to the first subcarrier of the first wanted signal and
at least a second respective subcarrier received in the first orthogonal beam
corresponding in frequency to the second subcarrier of the first wanted signal,
the second linear combination using the first linear relationship;
25 processing at least the first and second linear combinations to generate
one or more weights; and
applying the one or more weights to interference received in the beam
orthogonal to the first wanted signal to produce weighted interference and
combining the weighted interference with the received first wanted signal to
30 reduce interference to the first wanted signal.
24
2. A method according to claim 1, comprising generating the first
linear combination of the received first sub-carrier and at least the received
second sub-carrier by normalisation of the first and at least the second received
sub-carriers with respect to the known respective transmitted modulation.
5
3. A method according to claim 2, comprising generating the first
linear combination of the received first sub-carrier and at least the received
second sub-carrier by subtracting a linear combination of the normalised second
and at least a normalised third received sub-carrier from the normalised first
10 received subcarrier.
4. A method according to any preceding claim, comprising
generating the one or more weights by a process comprising forming a least
squares linear predictor of the first linear combination using the second linear
15 combination
5. A method according to claim 4, wherein the method comprises
forming a plurality of beams orthogonal to the first wanted signal beam and
wherein forming the least squares linear predictor comprises:
20 forming a covariance matrix from linear combinations having the first
linear relationship of components comprising received interference components
of the signals received in the plurality of beams orthogonal to the first wanted
signal beam corresponding to the first subcarrier;
forming a cross-correlation vector of the linear combinations of the
25 interference component of the received first subcarrier and the corresponding
linear combinations of received interference components of the signals received
in the plurality of beams orthogonal to the first wanted signal beam; and
dividing the cross-correlation vector by the covariance matrix.
30 6. A method according to claim 5, comprising forming the first
wanted signal beam from channel estimates derived from a plurality of sounding
25
operations which are processed to remove or de-weight measurements which
deviate from an expected result.
7. A method according to claim 6, comprising forming the plurality
5 of beams orthogonal to the first wanted beam by a process comprising using the
channel estimates.
8. A method according to claim 7, wherein forming orthogonal
beams to the first wanted signal beam or a plurality of wanted signal beams
10 comprises a method selected from a Gram-Schmidt procedure, a modified
Gram-Schmidt procedure and QR decomposition.
9. A method according to any preceding claim, wherein the first
wanted signal is an Orthogonal Frequency Division Modulation OFDM signal
15 and the first sub-carrier and at least the second sub-carrier are pilot tones of the
OFDM signal having known transmitted amplitude and phase modulation.
10. A method according to any preceding claim, wherein the multi element antenna array comprises a first dual-polar antenna element and a second
20 dual-polar antenna element disposed as a row of only two antenna elements,
wherein the array of antenna elements is disposed as a feed for a
reflector of an antenna arrangement