On the I-divergence Demodulation of the Nonnegative Impulse Response ISI Channel

Csiszár´s I-divergence is adopted as a discrepancy measure for the nonnegative impulse response intersymbol interference (ISI) channel demodulation. Both blind and nonblind I-divergence demodulation algorithms are discussed and numerically studied. Simulation results show that they have bit error rate (BER) performance close to the Viterbi algorithm for the one-dimensional channel. Furthermore, the asymptotic optimality of the I-divergence demodulation algorithms is studied theoretically. It is shown that the I-divergence discrepancy measure agrees with the Euclidean distance asymptotically. The role of the progressive thresholding in improving the BER performance is discussed. Estimation of the channel impulse response function is asymptotically maximum-likelihood optimal under the nonnegativity constraints. The complexity of the I-divergence detection algorithms is significantly less than that of the Viterbi algorithm for long ISI channels.