Turbo Equalization of Run Length Limited $(1,9)$ and Low Density Parity Check Code for Super Resolution Nearfield Structure Read Only Memory Discs with 60 nm Minimum Mark Length

概要

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Due to severe intersymbol interference and low signal-to-noise ratio of super resolution nearfield structure (SuperRENS) random read-outs, turbo equalization techniques are applied to lower bit error rates. A $d1k9r5$ run length limited (RLL) modulation code having minimum runlength $d = 1$, maximum runlength $k = 9$ and repeated minimum transition run limitation of $r = 5$ has been developed with emphasis on low joint bit detection and demodulation (super-trellis) complexity for use within turbo equalization schemes. Bit error rate (BER) performance of $d1k9r5$ code over partial response-channels is similar to 17pp code while the super-trellis detector complexity of $d1k9r5$ code is reduced. Low-frequency suppression performance of $d1k9r5$ code is similar to that of 17pp code under the same DC control redundancy. BER results for measured data from a 60 nm SuperRENS read only memory disc employing an InSb mask layer, using $d1k9r5$ modulation and a high-rate quasi-cyclic low density parity check (LDPC) code, correspond well to simulation results. Continuously decreasing BERs down to $2 \times 10^{-5}$ after five iterations show that a turbo equalization scheme incorporating $d1k9r5$ super-trellis detection can be successfully applied in SuperRENS storage systems together with an LDPC code.
2009-03-25