Digital Signal Processing Reference
In-Depth Information
q ( n )
0
H 0
s ( n )
0
q ( n )
1
H 1
s ( n )
1
(a)
q ( n )
M
H M −1
1
s ( n )
M
1
q ( n )
k
q ( n )
k
1 /H k
H k
s ( n )
k
s ( n )
k
s ( n )
k
s ( n )
k
(b)
q ( n )
0
s ( n )
0
s ( n )
0
q ( n )
1
s ( n )
1
s ( n )
1
(c)
q ( n )
M
1
s ( n )
M
s ( n )
M
1
1
Figure 11.6 . (a)Asetof M parallel independent channels, (b) the k th channel with
a zero-forcing equalizer, and (c) equivalent set of parallel independent channels for
capacity calculations, where
q k ( n )= q k ( n ) /H k .
from Eq. (11.32).
C k is the number of bits per sample that can be transmit-
tedreliablyonthe k th channel if channel coding of arbitrary sophistication is
available. The capacity of the parallel set of M channels is
1+ σ s k
.
M− 1
M− 1
C
=
C k =0 . 5
log
(11 . 34)
2
σ q k
k =0
k =0
From Chap. 22 (Sec. 22.3) we know that the power allocation which maximizes
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