Performance comparison of equalization and low-pass coding for holographic storage

We evaluated the comparative use of equalization and low-pass codes to tackle the ISI problem in a 2D-ISI channel, specifically holographic storage channel. We presented PRML equalization results with 6 different low-pass codes having various low-pass constraints. Detailed channel simulations were performed and the SNR gains through equalization or coding were translated into equivalent density gains using standard scaling laws. We showed that equalization tends to perform better than low-pass codes from the standpoint of overall density gain. We found that for both optical noise dominated and electronic noise dominated cases, equalization performs better. This is mostly because the density gains of low-pass codes were usually overwhelmed by the penalty paid in terms of the code-rate.