1 research outputs found
Refinements and Asymptotic performance of Bandwidth-efficient Turbo Product Codes
In this letter, a turbo product code (TPC) is combined
with multilevel modulations (8-phase-shift keying and
16-quadrature amplitude modulation). The component codes are
Bose–Chaudhuri–Hocquengem (BCH) or extended BCH. We
derive soft-input/soft-output modules based on the dual code,
with exact Euclidean metrics, and we show that the iterative TPC
decoder gains no advantage in performance from this. Next, we
evaluate asymptotic approximations for maximum-likelihood
(ML) decoding from a combinatorial approach that can be applied
to any bit-interleaved multilevel modulated code, once the first
term (or terms) of the Hamming weight spectrum are known.
For the TPCs and modulations studied in this letter, random bit
interleaving before modulation leads to improvedML asymptotes.
Simulations confirm that this advantage is maintained also under
iterative decoding