Method and device for estimating memory-enabled transmission channels
View Patent ↗A method for estimating memory-enabled transmission channels, having the following steps: determining a first estimation ĥ of the pulse response of the transmission channel; estimating the additive interferences of the transmission channel; and correcting the first channel estimation while taking into consideration the estimation of the additive interferences. The first channel estimation is performed using a matched filter or a least squares estimation.
1. A method for estimating a memory-enabled transmission channel, comprising the steps of:
determining a first estimation ĥ of a pulse response of the memory-enabled transmission channel;
performing an estimation of an intensity level σ 2 of an additive interference of the memory-enabled transmission channel; and
performing a correction of the first estimation of the pulse response by taking into consideration the estimation of the intensity level σ 2 of the additive interference of the memory-enabled transmission channel, wherein an amount of correction of the first estimation varies depending on the estimated intensity level σ 2 of the additive interference.
2. The method according to claim 1 , wherein:
the step of determining the first estimation is performed by a matched filter.
3. The method according to claim 2 , wherein:
the matched filter is given by
h
^
_
=
1
γ
·
G
*
T
·
e
_
ref
,
where
G
=
(
r
W
r
W
-
1
…
r
1
r
W
+
1
r
w
r
2
·
·
·
r
W
+
N
-
1
r
W
+
N
-
2
…
r
N
)
and
γ
=
N
L
·
r
_
2
r =(r 1 , . . . , r L ) being a reference signal used for purposes of channel estimation, γ is a scaling factor, N is a length of a receiving-signal portion, L is a length of a chip pulse, G is a channel characteristic matrix and e ref −(e refstart , . . . e refstart+N−1 ) being a received signal part that is not influenced by data transmitted before and after the reference signal.
4. The method according to claim 1 , wherein:
the first estimation is given by a least squares estimation.
5. The method according to claim 4 , wherein:
the least squares estimation is given by
ĥ =( G*· T ·G ) −1 ·G* T · e ref .
6. The method according to claim 1 , wherein:
the step of performing the estimation of the intensity level σ 2 of the additive interference is given by
σ 2 =θ( E −( 1+ f )·γ∥ ĥ ∥ 2 )/( N −(1+ f ))
with
θ
(
x
)
=
{
x
,
if
x
>
0
otherwise
,
0
wherein f is a frequency value, N indicates a length of a receiving-signal portion and E is an energy value.
7. The method according to claim 1 , wherein:
the correction of the first estimation ĥ k of the k th component, k 0 {1, . . . , W}, of estimation vector ĥ of the pulse response h is given by
h
^
k
=
{
0
,
if
h
k
2
<
σ
2
/
γ
otherwise
h
k
.
8. The method according to claim 1 , wherein:
the correction of the first estimation ĥ k of the k th component, k 0 {1, . . . , W}, of estimation vector ĥ of the pulse response h is given by
h
^
k
=
θ
(
h
^
k
2
-
σ
2
/
γ
)
·
h
^
k
/
h
^
,
if ĥ k ≅0, and
otherwise
ĥ k =0.
9. The method according to claim 1 , wherein:
the correction of the first estimation is given by a projected onto convex sets (POCS) algorithm.
10. The method according to claim 1 , wherein:
the correction of the first estimation is given by a minimum mean square error (MMSE) algorithm.
11. The method according to claim 10 , wherein:
the MMSE algorithm is given by
ĥ =( G* T ·G+σ 2 ·I ) −1 ·G* T − e ref
I being the unit matrix.
12. A device for estimating a memory-enabled transmission channel, comprising:
a channel estimator;
an estimator of an intensity level σ 2 of an additive interference, the channel estimator and the estimator of the additive interference act on a received signal; and
channel estimation correcting element for correcting a signal of the channel estimator by taking into consideration an output signal of the estimator of the intensity level σ 2 of the additive interference of the memory-enabled transmission channel, wherein an amount of correction of the signal varies depending on the estimated intensity level σ 2 of the additive interference.