DocumentCode :
1748073
Title :
Turbo codes with non-uniform constellations
Author :
Fragouli, Christine ; Wesel, Richard D. ; Sommer, D. ; Fettweis, G.P.
Author_Institution :
California Univ., Los Angeles, CA, USA
Volume :
1
fYear :
2001
fDate :
11-14 Jun 2001
Firstpage :
70
Abstract :
This paper presents parallel concatenated turbo codes that employ a non-uniform constellation to achieve shaping gain. The output signal approximates the Gaussian distribution by using equally likely signals with unequal spacing (a non-uniform constellation). The small distance of points near the center of the constellation may lead to a small overall free distance and thus a high error floor for turbo codes. We avoid this situation by a two-step design procedure, that first creates an interleaver, and then identifies the constituent encoders that maximize the turbo code free distance. Simulation results for 4 bits/sec/Hz show that this use of shaping can offer an improvement of approximately 0.2 dB for turbo codes
Keywords :
Gaussian distribution; concatenated codes; interleaved codes; trellis coded modulation; turbo codes; Gaussian distribution; constituent encoders; error floor; free distance maximization; interleaver; nonuniform constellation; parallel concatenated turbo codes; shaping gain; simulation results; trellis coded modulation; two-step design procedure; AWGN; Concatenated codes; Constellation diagram; Decoding; Gaussian distribution; Modulation coding; Peak to average power ratio; Region 5; Transmitters; Turbo codes;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Communications, 2001. ICC 2001. IEEE International Conference on
Conference_Location :
Helsinki
Print_ISBN :
0-7803-7097-1
Type :
conf
DOI :
10.1109/ICC.2001.936275
Filename :
936275
Link To Document :
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