US 7,623,579 B2Granted

Method of demodulating OFDM type signals in the presence of strong co-channel interference signals

AssigneesThales, Tdf

InventorsDenis Masse, François Pipon, Rym Mhiri

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Abstract

A method of demodulating a signal in a transmission system where the modulation includes several substantially orthogonal subcarriers, and the vector of the propagation channel H[n,k] is known or the received signal includes at least pilot symbols emitting reference data. The method includes at least one step of estimating the symbol a[n,k] emitted on the kth subcarrier of the nth symbol of the modulation using a recombination step weighting the various signals received after synchronization and demodulation x[n,k].

Claims11

Dependent claims

A method of demodulating a signal in a transmission system where the modulation includes several substantially orthogonal subcarriers, wherein the vector of the propagation channel H[n,k] is known, or the received signal, including at least pilot symbols transmitting reference data, the method comprising at least one step of:

estimating the symbol a[n,k] emitted on the kth subcarrier of the nth symbol of the modulation using a recombination step weighting the various signals received x[n,k] after synchronization and demodulation,
wherein the recombination step uses a recombination vector defined by the relation
g[n]=Rxx−1[n].rxd[n] (3)
where:
Rxx[n]. is the correlation matrix of a signal to be spatially filtered;
and
rxd[n] is the vector of intercorrelation between the signal to be spatially filtered and a reference sequence;
and
wherein the estimation of the correlation matrix and of the intercorrelation vector is performed using the following formulae:
R
^
xx
⁡
[
n
]
=
∑
l
=
-
L
1
L
2
⁢
(
∑
k
∈
K
l
⁢
x
⁡
[
n
+
l
,
k
]
⁢
x
H
⁡
[
n
+
l
,
k
]
)
(
4
)
r
^
xa
⁡
[
n
]
=
∑
l
=
-
L
1
L
2
⁢
(
∑
k
∈
K
l
⁢
x
⁡
[
n
+
l
,
k
]
⁢
a
*
⁡
[
k
]
)
(
5
)
where:
the index 1 corresponds to the use of the symbols of the modulation before, L1 symbols before, and L2 symbols after the symbol considered so as to improve the estimation of the correlation matrix,
Kl is the set of indices of the continuous pilots and/or of the dispersed pilots.

101 more elements

A method of demodulating a signal in a transmission system where the modulation comprises several substantially orthogonal subcarriers, the received signal including at least pilot symbols transmitting reference data, the method comprising:

a step of estimating the vector of the propagation channel H[n, k], and
at least one step of estimating the symbol a[n,k] emitted on the kth subcarrier of the nth symbol of the modulation using a recombination step weighting the various signals received x[n,k] after synchronization and demodulation,
wherein the recombination step uses a recombination vector defined by the relation
g[n]=Rxx−1[n].H[n,k] (8)
where:
Rxx[n] is the correlation matrix of a signal to be spatially filtered;
wherein the estimation of the correlation matrix and of the intercorrelation vector is performed using the following formulae:
R
^
xx
⁡
[
n
]
=
∑
l
=
-
L
1
L
2
⁢
(
∑
k
∈
K
l
⁢
x
⁡
[
n
+
l
,
k
]
⁢
x
H
⁡
[
n
+
l
,
k
]
)
(
4
)
r
^
xa
⁡
[
n
]
=
∑
l
=
-
L
1
L
2
⁢
(
∑
k
∈
K
l
⁢
x
⁡
[
n
+
l
,
k
]
⁢
a
*
⁡
[
k
]
)
(
5
)
where:
the index 1 corresponds to the use of the symbols of the modulation before and after the symbol considered so as to improve the estimation of the correlation matrix,
Kl is the set of indices of the continuous pilots and/or of the dispersed pilots.

99 more elements

Dependencies are inferred from the claim text.

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Abstract