A New Efficient Error Correctible Modulation Code for Holographic Data Storage

Abstract

Paramagnetic colloidal particles move in the potential energy landscape of a magnetically modulated bubble lattice of a magnetic garnet film. The modulation causes the energy minima to alternate between positions above the centres of the bubbles and interstitial positions. The particles deterministically follow the time-dependent positions of the energy minima until the minima become unstable in one or several directions and allow the particles to hop to a new minimum. We control the time delay between instabilities of the minima in alternative directions by the angle of the external magnetic field with the crystallographic directions of the bubble lattice. When the time delay is large, the particles deterministically hop to the next minimum along the direction that becomes unstable first. When the time delay is short, diffusion of the particle in the marginal potential randomizes the choice of the hopping directions or the choice of the transport network. Gradual changes of the external field direction from 0 • to 30 • lead to a continuous crossover from a deterministic to a fully stochastic path of the colloids.

Modulation Codes for Optical Data Storage

“…The 9:12 pseudo-balanced code (Hwang et al, 2002) is a strip code which maps 9-bit information into a 12-bit codeword with a code rate of ¾. It is similar to the 8:12 balanced modulation code, but with higher code rate by relaxing the balanced constraint to allow certain degree of codeword imbalance.…”

“…Then the Viterbi algorithm finds the best state sequence using those aforementioned distances as branch metrics. In (Hwang et al, 2002), it is shown that the 9:12 pseudo-balanced code, though with a higher code rate, provides similar performance as the 8:12 balanced strip code.…”

A Modified Low-Density Parity-Check Decoder for Holographic Data Storage System

“…1) However, because of the denser recording and faster readout of data in HDDS, severe noise and impairment can occur in the retrieved data; therefore, it requires an effective signal processing scheme for reliable data readout. [2][3][4] Low-density parity-check (LDPC) codes have a performance near the Shannon limit when decoded using an iterative probabilistic decoding algorithm. Also, they have a low error floor with a large minimum distance and a highly parallel decoding scheme.…”

Efficient Balanced Code Using Viterbi Algorithm and Section Division for Holographic Data Storage

“…Therefore, in previous research, a 9 : 12 pseudo balanced code (PBC) error correctible modulation code using the Viterbi algorithm is proposed and evaluated. 3) Similarly, we propose the error correctible balanced code that uses section dividing and parity appending. Also, we use a codeword look-up table with 2 as a hamming distance.…”