Asymptotics Of The Error Probability In Quasi-Static Binary Symmetric Channels

This paper provides an asymptotic expansion of the error probability, as the codeword length n goes to infinity, in quasi-static binary symmetric channels. After the leading term, namely the outage probability, the next two terms are found to be proportional to log n/n, and 1/n respectively. Explicit characterizations of the respective coefficients are given. The resulting expansion gives an approximation to the random -coding union bound, accurate even at small codeword lengths.