492 Problem 9.33
In the textbook, the capacity of the NEXTdominated channel is derived as
l IHNEXT(f)I2]
C = log £1+ df
29L 2 Vitfz
where Fa is the set of positive and negative frequencies for which Sx(f) > 0, where Sx(f) is the
power spectral density
Cha ter 10
Error-Control Coding
Problem 10.1
The matrix of transition probabilities of a discrete memoryless channel with 2 inputs and
Q outputs may be written as
P = to I0) p(1 I0) p(2 I0) p(Q-l lo)
(0 I1) p(1l1) p(2 I1) p(Q-l I1)
For a symmetric
The generalized encoder and decoder presented here are described in Valenti (1998); see the
Bibliography.
Problem 10.35
The decoding scheme used for turbo codes relies on the assumption that the bit probabilities
remain independent from one iteration to
Each of these two paths is extended in two ways to form four paths of length 2; their
squared Euclidean distances from the received sequence are as follows:
(a)
dzl = 0.01 + (0.0 - 1.1)2 = 1.22
(122:2 = 3.6! + (0.0 - 0.9)2 = 4.42
(b)
dis = 0.01 + (0.0