= Channel encoder
{title2=$f:\{1,\ldots,M\}\to\mathcal X^n$}
= Encoder
{synonym}
For deterministic block transmission without feedback, a <channel encoder> maps each message label to an input word of length $n$ over an <alphabet> $\mathcal X$. These words are the <codewords> of a <block code>. Distinct messages should have distinct <codewords>: if two labels give the same word, even a noiseless <communication channel> cannot tell them apart. The <channel encoder> may add redundancy, so the transmitted word can be longer than the message representation.
Back to article page
