EURASIP Journal on Applied Signal Processing
Volume 2006 (2006), Article ID 65716, 13 pages
doi:10.1155/ASP/2006/65716
Abstract
While most existing loading algorithms for xDSL-DMT systems strive
for the optimal energy distribution to maximize their rate, the
amounts of bits loaded to subcarriers are constrained to be
integers and the associated granularity losses can represent a
significant percentage of the achievable data rate, especially in
the presence of the peak-power constraint. To recover these
losses, we propose a fine-granularity loading scheme
using joint optimization of adaptive modulation and flexible
coding parameters based on programmable Reed-Solomon (RS) codes
and bit-error probability criterion. Illustrative examples of
applications to VDSL-DMT systems indicate that the proposed scheme
can offer a rate increase of about 20% in most cases as
compared to various existing integer-bit-loading algorithms. This
improvement is in good agreement with the theoretical estimates
developed to quantify the granularity loss.
