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

摘要

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 d1 k9r5 code over partial response-channels is similar to 17pp code while the super-trellis detector complexity of d1 k9r5 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 d1 k9r5 modulation and a high-rate quasi-cyclic low density parity check (LDPC) code, correspond well to simulation results. Continuously decreasing BERs down to 2 × 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.