DocumentCode :
1486882
Title :
Time-division versus superposition coded modulation schemes for unequal error protection
Author :
Gadkari, Shrinivas ; Rose, Kenneth
Author_Institution :
Dept. of Electr. & Comput. Eng., California Univ., Santa Barbara, CA, USA
Volume :
47
Issue :
3
fYear :
1999
fDate :
3/1/1999 12:00:00 AM
Firstpage :
370
Lastpage :
379
Abstract :
This paper is concerned with the design problem of coded modulation schemes which provide unequal error protection (UEP) against Gaussian noise. Starting with the case of two bit streams, we consider two classes of UEP schemes: time-division coded modulation (TDCM) and superposition coded modulation (SCM). The early result of Bergmanns and Cover (1974) ensures the asymptotic superiority of SCM. However, accounting for the fact that practical channel codes do not achieve capacity, we show that the validity of this result depends on the prescribed degree of inequality in protection of the streams. To complement the straightforward design and use of TDCM schemes, we propose methods to decode and design SCM schemes. The design examples substantiate the conclusions obtained from performance analysis. We extend the results to the case of UEP of multiple (more than two) bit streams, where a hybrid of SCM and TDCM must also be considered. We show that, for a large range of unequal protection levels, the hybrid scheme outperforms both SCM and TDCM
Keywords :
Gaussian noise; channel coding; decoding; error correction codes; modulation coding; Gaussian noise; TDCM; bit streams; decoding; performance analysis; practical channel codes; superposition coded modulation; time-division coded modulation; unequal error protection; Decoding; Digital signal processing; Error correction codes; Mobile communication; Modulation coding; Noise level; Protection; Quadrature amplitude modulation; Time-varying channels; Transmitters;
fLanguage :
English
Journal_Title :
Communications, IEEE Transactions on
Publisher :
ieee
ISSN :
0090-6778
Type :
jour
DOI :
10.1109/26.752817
Filename :
752817
Link To Document :
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