Repeat-Accumulate Code
Encyclopedia
In computer science
, repeat-accumulate codes (RA codes) are a low complexity class of error-correcting codes. They were devised so that their ensemble weight distributions are easy to derive. RA codes were introduced by Divsalar et al.
In an RA code, an information block of length
is repeated 
times, scrambled by an interleaver of size 
, and then encoded by a rate 1 accumulator. The accumulator can be viewed as a truncated rate 1 recursive convolutional encoder with transfer function 
, but Divsalar et al. prefer to think of it as a block code whose input block 
and output block 
are related by the formula 
and 
for 
. The encoding time for RA codes is linear and their rate is 
. They are nonsystematic.
Computer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
, repeat-accumulate codes (RA codes) are a low complexity class of error-correcting codes. They were devised so that their ensemble weight distributions are easy to derive. RA codes were introduced by Divsalar et al.
In an RA code, an information block of length
is repeated times, scrambled by an interleaver of size , and then encoded by a rate 1 accumulator. The accumulator can be viewed as a truncated rate 1 recursive convolutional encoder with transfer function , but Divsalar et al. prefer to think of it as a block code whose input block and output block are related by the formula and for . The encoding time for RA codes is linear and their rate is . They are nonsystematic.