Classical transceiver techniques - Signal Processing and Optimization for Transceiver Systems - page 197

1.5 0.25

1

− 0.5

stage 0

2.25

cost 3.86

1.5 1.5

0.25

1

cost 3.06
cost 0.26

0.5 − 0.5

− 0.5

stage 1

cost 3.46

2.25

− 1.5

cost 8.35

1.5

1.5

3.06

1

cost 1.95
cost 3.15

− 0.5

0.5 − 0.5 0.5

− 0.5

stage 2

cost 0.75

0.26 − 1.5

cost 3.91

1.5 1.5

1.95

1

cost 0.91
cost 2.31

− 0.5 0.5 0.5 − 0.5

stage 3

cost 3.31

− 1.5 0.75 − 1.5

cost 1.07

1.5

1.5 0.91

1

cost 2.67
cost 3.47

− 0.5 − 0.5

− 0.5 0.5 0.5 0.5

stage 4

cost 9.07

− 1.5 − 1.5

2.31

1.5 1.5

1.07

1

− 0.5

− 0.5 0.5

final pruned trellis

3.47

− 1.5

Figure 5.18 . Successive stages in the development of the Viterbi algorithm. The
noisy channel output is 1 , − 0 . 4 , − 0 . 8 , 0 . 1 , 1 . 1 ,... From these the first four symbols of
the transmitted signal are estimated as 1 , − 1 , − 1 , 1 .