Turbo-Product-Coded QVSB

In this paper, a turbo-product-coded, quadrature-vestigial-sideband (QVSB), digital modulation and coding scheme are presented. This scheme is more complex than the VSB modulation and coding format employed for high-definition television; and it achieves spectral-efficiency performance within 4 to 5dB of the Shannon-Bound, with relatively conservative turbo-product-codes. Special QVSB bandlimiting, which is more restrictive than Nyquist filtering, is used to minimize crosstalk between its dual overlapping, quadrature data channels. To unravel the residual cross-channel interference for detection, a quadrature-crosstalk maximum-likelihood-sequence-estimator (QC-MLSE) is needed. The QC-MLSE output is 'hard- to soft-decision converted' to improve subsequent decoding performance. An external interleaver was also used to augment the turbo-product-code's internal helical interleaver, for improved performance