Digital Signal Processing Reference
In-Depth Information
with the weighted term E
w i 1
R u . This term can be deduced from Relation
1.78 by writing it for
=
R u , which leads to
2 E
2 R u
g 2 [ u i ]
E
u i
2
2
2
2
2
v
E
w i
R u =
E
w i 1
R u
2
µ
h G E
w i 1
R u + µ
w i 1
R u + σ
2
with the weighted term E
R u and so forth. The procedure terminates and
leads to the following state-space model:
w i
= F + µ
e 2 W
2
2
2
v Y
W
Y
+ µ
σ
,
(1.82)
i
i
1
where the M
×
1 vectors
{W i ,
Y}
are defined by
E
g 2 [ u i ]
2
2
u i
/
E
w i
E
g 2 [ u i ]
2
R u
2
E
w i
u i
R u /
.
.
i
=
W
=
Y
,
,
(1.83)
E
g 2 [ u i ]
2
R M 2
u
2
R M 2
u
E
w i
u i
/
E
g 2 [ u i ]
2
R M 1
u
E
w i
2
R M 1
u
u i
/
the M
×
M matrix
F
is given by
1
2
µ
h G
0
1
2
µ
h G
0
0
1
2
µ
h G
=
F
0
0
1
2
µ
h G
2
µ
p 0 h G
2
µ
p 1 h G
...
2
µ
p M 2 h G
1
+
2
µ
p M 1 h G
and
=
{
...
} .
e 2
col
0 , 1 , 0 ,
, 0
Also,
E 1
g [ u i ]
h G
=
.
The evolution of the top entry of
W
i describes the mean-square deviation of
2 , while the evolution of the second entry of
the filter, E
i relates to
the learning behavior of the filter. The model (Equation 1.82) is an alternative
to Equation 1.22 for adaptive filters with data nonlinearities; it is based on
assumptions in Listing 1.76.
w i
W
1.12.5.3 Steady-State Performance
The variance Relation 1.78 can also be used to approximate the steady-state
performance of data-normalized adaptive filters. Writing it for
=
I ,
2 E
E
2
u i
2
2
2
2
2
v
E
w i
=
E
w i 1
2
µ
h G E
w i 1
R u + µ
w i 1
R u + σ
g 2 [ u i ]
(1.84)
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