Spatially coupled low-density parity-check error correction for holographic data storage

Abstract

The spatially coupled low-density parity-check (SC-LDPC) was considered for holographic data storage. The superiority of SC-LDPC was studied by simulation. The simulations show that the performance of SC-LDPC depends on the lifting number, and when the lifting number is over 100, SC-LDPC shows better error correctability compared with irregular LDPC. SC-LDPC is applied to the 5:9 modulation code, which is one of the differential codes. The error-free point is near 2.8 dB and over 10−1 can be corrected in simulation. From these simulation results, this error correction code can be applied to actual holographic data storage test equipment. Results showed that 8 × 10−2 can be corrected, furthermore it works effectively and shows good error correctability.

[Paper] Efficient Decoding Method for Holographic Data Storage Combining Convolutional Neural Network and Spatially Coupled Low-Density Parity-Check Code

“…Among them, the spatially coupled LDPC (SC-LDPC) code 15) is one of the strongest error correction codes that approaches the Shannon limit, based on the LDPC code 16) . We confirmed that the capability of error correction of the SC-LDPC code outperforms that of the LDPC code in the HDS 17) .…”

“…The conventional LLR in the HDS system is given as follows: 17) (4) where, d denotes the Euclidean distance between two blocks; Brep, the standardized reproduced block with bipolar conversion (the maximum is mapped to -1, and the minimum is mapped to 1); and B rep , the bipolar conversed block that is remodulated from the demodulated bits. Figure 3 presents an example of the LLR calculation process.…”

“…However, the noise superimposed on the data pages during the recording and reproduction processes contain various types of optical noise, such as fixed-pattern noise and lens aberrations as well as AWGN. Accordingly, the use of LLRs, based on the AWGN channel in previous studies 17,20) , cannot take full advantage of the sumproduct decoding.…”

[Paper] Spatial Filter and Combination of Angle and Peristrophic Multiplexings to Achieve Recording Density of 1 Tbit/inch² in Holographic Data Storage

“…When the special coupled lowdensity parity check code was used as the error correction code, the reproduced data with a bER of less than 8.0 × 10 -2 could be decoded error free. 17) Therefore, these three diameters can be used when data pages are recorded without peristrophic multiplexing. However, when the multiplex page number increases by using angle and peristrophic multiplexings, the bER of the reproduced data will increase due to the scatter noise in the recording medium and crosstalk from neighboring holograms.…”

[Invited Paper] Investigation of Noise Characteristics of Multivalued Signals and Estimation of Single-page Storage Density in Holographic Data Storage

“…This is because increasing the number of multivalued signals increases crosstalk between symbols and increases detection errors. Since errors must be corrected by an error correction method [29][30][31] that the system adopted, the error rate should be kept less than a specific value allowed by the system. For example, when the error rate increased by increasing the number of multivalued signals, it should be compensated by loosening other parameters, such as the aperture size and the angular spacing for multiplexing, in order to keep it within the allowable error rate.…”