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Typically, the soft output is used as the soft input to an outer decoder in a system using concatenated codes, or to modify the input to a further decoding iteration such as in the decoding of turbo codes. Examples include the BCJR algorithm and the soft output Viterbi algorithm.
In cryptography, Cobra is the general name of a family of data-dependent permutation based block ciphers: Cobra-S128, Cobra-F64a, Cobra-F64b, Cobra-H64, and Cobra-H128.In each of these names, the number indicates the cipher's block size, and the capital letter indicates whether it is optimized for implementation in software, firmware, or hardware.
Whereas a hard-decision decoder operates on data that take on a fixed set of possible values (typically 0 or 1 in a binary code), the inputs to a soft-decision decoder may take on a whole range of values in-between. This extra information indicates the reliability of each input data point, and is used to form better estimates of the original data.
The first element of a CIRC decoder is a relatively weak inner (32,28) Reed–Solomon code, shortened from a (255,251) code with 8-bit symbols. This code can correct up to 2 byte errors per 32-byte block.
The name "turbo code" arose from the feedback loop used during normal turbo code decoding, which was analogized to the exhaust feedback used for engine turbocharging. Hagenauer has argued the term turbo code is a misnomer since there is no feedback involved in the encoding process.
A Barker code has a maximum autocorrelation sequence which has sidelobes no larger than 1. It is generally accepted that no other perfect binary phase codes exist. [9] [10] (It has been proven that there are no further odd-length codes, [11] nor even-length codes of N < 10 22. [12])
One of the applications of locally decodable codes in complexity theory is hardness amplification. Using LDCs with polynomial codeword length and polylogarithmic query complexity, one can take a function : {,} {,} that is hard to solve on worst case inputs and design a function ′: {,} {,} that is hard to compute on average case inputs.
A Viterbi decoder uses the Viterbi algorithm for decoding a bitstream that has been encoded using a convolutional code or trellis code. There are other algorithms for decoding a convolutionally encoded stream (for example, the Fano algorithm ).