Performance analysis of linear codes under maximum likelihood decoding at low rates

Or a given linear code, a lower bound on the error exponent under maximum likelihood decoding is investigated at low rates. or a given linear code, a lower bound on the error exponent under maximum likelihood decoding is investigated at low rates. F In the analysis of the decoding error probability, it is important to characterize the error exponent, since it indicates how fast the probability of decoding error converges to zero asymptotically. Over a symmetric memoryless channel, an error exponent is derived for a given linear code. A sufficient condition for achieving the expurgated exponent, which is the best among known error exponents at low rates, is given. Over a general discrete memoryless channel, the same analysis shows the expected error exponent of an ensemble of coset codes generated by a given linear code.