Revisiting augmented decoding techniques for LTE Turbo Codes

This paper revisits several methods used in iterative decoders to improve the performance of the LTE Turbo code for small information blocks. By considering the iterative decoder as a chaotic system, some explanations are given on the unexpected behavior of several post-processing algorithms. A "dither-inspired" algorithm, called blind candidate decoding, is proposed. This algorithm improves error correction by performing several decoding attempts from a set of perturbed input. Combined with the use of the CRC as an outer code, a performance improvement of up to 1 dB in signal to noise ratio can be obtained for a frame error rate of 10
⁻³
. Moreover, a stopping criterion based on the Euclidean distance between the output and the input is proposed to mitigate the critical problem of undetected errors.