Expander code

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Expander codes
bipartite expander graph
Classification
Type	Linear block code
Block length	${\displaystyle n}$
Message length	${\displaystyle n-m}$
Rate	${\displaystyle 1-m/n}$
Distance	${\displaystyle 2(1-\epsilon )\gamma \cdot n}$
Alphabet size	${\displaystyle 2}$
Notation	${\displaystyle [n,n-m,2(1-\epsilon )\gamma \cdot n]_{2}}$-code
v t e

In coding theory, expander codes form a class of error-correcting codes that are constructed from bipartite expander graphs. Along with Justesen codes, expander codes are of particular interest since they have a constant positive rate, a constant positive relative distance, and a constant alphabet size. In fact, the alphabet contains only two elements, so expander codes belong to the class of binary codes. Furthermore, expander codes can be both encoded and decoded in time proportional to the block length of the code.