The error floor is a phenomenon encountered in modern iterated
sparse graph
In mathematics, a dense graph is a graph in which the number of edges is close to the maximal number of edges (where every pair of vertices is connected by one edge). The opposite, a graph with only a few edges, is a sparse graph. The distinction ...
-based
error correcting codes like
LDPC codes
In information theory, a low-density parity-check (LDPC) code is a linear error correcting code, a method of transmitting a message over a noisy transmission channel. An LDPC code is constructed using a sparse Tanner graph (subclass of the bipa ...
and
turbo codes. When the
bit error ratio (BER) is plotted for conventional codes like
Reed–Solomon codes under algebraic decoding or for
convolutional codes under
Viterbi decoding, the BER steadily decreases in the form of a curve as the
SNR condition becomes better. For LDPC codes and turbo codes there is a point after which the curve does not fall as quickly as before, in other words, there is a region in which performance flattens. This region is called the ''error floor region''. The region just before the sudden drop in performance is called the ''waterfall region''.
Error floors are usually attributed to low-weight codewords (in the case of Turbo codes) and trapping sets or near-codewords (in the case of LDPC codes).
Thomas Richardson: ''Error floors of LDPC codes''
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References
Error detection and correction
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