가중 비이진 RA 부호의 새로운 중단 기준 제안
- 가중 비이진 RA 부호의 새로운 중단 기준 제안
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- In this thesis, we develope a new stopping criterion for the weighted nonbinary
repeat-accumulate (WNRA) codes over GF(q). The decoding complexity
of WNRA codes increases in proportion to the modulation order. Similar to
binary repeat-accumulate (RA) codes, a stopping criterion can be a very effective
method in order to reduce the decoding complexity of WNRA decoders with
some performance degradation.
The message vectors in nonbinary belief-propagation (BP) decoder is updated
in every iteration. In addition, one of the elements in message vectors becomes
more dominant whenever the iteration proceeds. In this reason, observing the
behaviors of message vectors in every iterations can provide the information of
decoding progress indicating the possiblity of successful decoding.
We propose a new stopping criterion which requires negligible additional
complexity with little performance degradation. By choosing the threshold
value adequately, the proposed stopping criterion have the additional complexity
only in bit-wise comparison operations. The simulation results show that
the decoding algorithm by using the proposed stopping criterion reduces the
average number of iterations of BP decoders for WNRA codes over GF(q) with
q-ary frequency-shift keying (FSK) by less than one half compared to the algorithm
by using the fixed number of iterations within 0.05 dB frame error rate
(FER) performance degradation at FER 10¡1.
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