Design of good low-rate coding schemes for ISI channels based on spectral shaping

This paper proposes two low-complexity coding schemes for intersymbol interference (ISI) channels that perform close to the channel capacity. The first scheme is a serial concatenation of an outer code and a spectral shaping inner code. The second scheme is a parallel concatenation of two component trellis codes that are designed to be spectrally matched to the channel. Analysis using extrinsic information transfer (EXIT) functions and bit-error-rate (BER) simulations shows that both schemes surpass the independent identically distributed (i.i.d.) channel capacity and outperform other existing schemes.