  We consider the problem of reliable communication over non-binary
insertion/deletion channels where symbols are randomly deleted from or inserted
in the transmitted sequence and all symbols are corrupted by additive white
Gaussian noise. To this end, we utilize the inherent redundancy achievable in
non-binary symbol sets by first expanding the symbol set and then allocating
part of the bits associated with each symbol to watermark symbols. The
watermark sequence, known at the receiver, is then used by a forward-backward
algorithm to provide soft information for an outer code which decodes the
transmitted sequence. Through numerical results and discussions, we evaluate
the performance of the proposed solution and show that it leads to significant
system ability to detect and correct insertions/deletions. We also provide
estimates of the maximum achievable information rates of the system, compare
them with the available bounds, and construct practical codes capable of
approaching these limits.
