The error floor is a phenomenon encountered in modern iterated
sparse graph
In mathematics, a dense graph is a Graph (discrete mathematics), graph in which the number of edges is close to the maximal number of edges (where every pair of Vertex (graph theory), vertices is connected by one edge). The opposite, a graph with ...
-based
error correcting codes
In computing, telecommunication, information theory, and coding theory, forward error correction (FEC) or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels.
The centra ...
like
LDPC codes and
turbo codes. When the
bit error ratio
In digital transmission, the number of bit errors is the number of received bits of a data stream over a communication channel that have been altered due to noise, interference, distortion or bit synchronization errors.
The bit error rate ( ...
(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 The initialism SNR may refer to:
* Signal-to-noise ratio
Signal-to-noise ratio (SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. SNR is defined as the ratio ...
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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