Efficient complexity reduction technique in trellis decoding algorithm

Satellite Commun. Syst. Dept., Electron. & Telecommun. Res. Inst., Daejeon
Electronics Letters (Impact Factor: 0.93). 02/1999; 35(1):16 - 17. DOI: 10.1049/el:19990081
Source: IEEE Xplore


An efficient reduced search trellis decoding algorithm in which
the decoder selects a part of existing paths by using a threshold value
of the path metric is proposed. The threshold value at each time stage
of the trellis is found by simply investigating the statistics of the
path metrics, and does not require any prior knowledge such as the
signal-to-noise ratio

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    ABSTRACT: In this paper, we propose an efficient reduced-search SOVA (soft output Viterbi algorithm) for block turbo codes. To reduce complexity, the decoder selects a part of the existing paths using the statistics of the path metrics. In addition, we compensate for the performance degradation incurred from soft output values at the parity part of the trellis that were too optimistically estimated, so that the performance of the reduced-search decoder almost approximates that of a full-search decoder. Our simulation results reveal that the proposed reduced-search method can reduce the complexity by about 10 times with just about 0.1dB performance degradation in coding gain.
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