Coded modulation for E/sup 2/PR4 and ME/sup 2/PR4 channels

We consider a multilevel modulation scheme based on: 1) a structured set partition (SSP) of partial-response (PR) channel output words; 2) a set of conventional block codes with different error-correcting capabilities; and 3) a Viterbi detector searching for the two best paths on the channel trellis. For the classic and modified target polynomials, examples of SSPs with the good spectra of minimum Euclidean distances are given. Bit error rates (BERs) of the proposed scheme are investigated for the conventional (E/sup 2/PR4) and modified (ME/sup 2/PR4) channels with the target polynomials 1+2D-2D/sup 3/-D/sup 4/ and 5+4D-3D/sup 2/-4D/sup 3/-2D/sup 4/, respectively. Results of simulations show that a gain of 3.4 dB can be achieved for linear densities of 2.5 to 3.0 and BER of 10/sup -6/ without using any additional distance enhancing constraints [such as d=1, maximum transition run (MTR), or quasi-MTR].