DVB-S2 LDPC Decoding Using Robust Check Node Update Approximations

Broadband satellite services to fixed terminals are
\ncurrently offered in the forward link by the 2nd Generation (2G)
\nDigital Video Broadcasting Satellite (DVB-S2) standard. For this
\nstandard the use of powerful Low-Density Parity-Check (LDPC)
\nerror correcting codes has been adopted performing within approximately
\n1 dB from the Shannon capacity limit. This paper
\nstudies and compares for the first time in a systematic manner
\ndifferent approximation methods used in check node update
\ncomputation of DVB-S2 LDPC decoding with the aim of reducing
\ncomputational complexity. Various performance evaluation results
\nare presented for a wide range of DVB-S2 parameters, such
\nas LDPC codeword size, coding rate, modulation format and including
\nseveral decoding algorithms. It is shown that the proposed
\ncheck node update approximations have a robust behavior, i.e.
\nthe resulting performance is quite independent of the DVB-S2
\nmodulation and coding parameters. It is further shown that these
\napproximations perform very close to the optimal Sum-Product
\nAlgorithm (SPA) in degradation, which is less than 0.2 dB. Despite
\nthis small degradation, the reduction in computational complexity
\ncompared to the optimal SPA is significant and can be as high as
\n40% in computational time savings.