PPT Slide

Trellis coded modulation (Ungerboeck, 1982) :coding specific to modulation scheme improves bandwidth efficiency

16-QAM

1st partition

2nd partition

3rd partition

4th partition

0000 1000 0100 1100 0010 1010 0110 1110 0001 1001 0101 1101 0011 1011 0111 1111

rate 2/3

‘symbol’

encoder

i1

i2

i3

c1

c3

c4

c2

c1 selects the 1st set partition

c2 selects the 2nd set partition

c3 selects the 4rd set partition

c4 selects the 4th set partition

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

‘less protected’ bits are assigned to larger Euclidian distances

larger code rates with good error correction !

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