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Coding and Signal Processing for Two-Dimensional Optical Storage (TwoDOS)

Coding and Signal Processing for Two-Dimensional Optical Storage (TwoDOS)

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Coding and Signal Processing for Two-Dimensional Optical Storage (TwoDOS)

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  1. Coding and Signal Processing for Two-Dimensional Optical Storage(TwoDOS) DIMACS March 23 2004 Wim Coene

  2. Outline • Introduction • TwoDOS Concept • Write-Channel • Signal-Patterns • Read-Out and Test-Player • Modulation Encoding • Signal Processing and Bit-Detection • Experimental Results • Conclusion

  3. Principle of Traditional Optical Storage 010010110111011000 001101110001001110 101111001011011000 pit land track user data eye-pattern disc track lens spiral PDIC Laser Signal Processing

  4. 3 Generations of Optical Recording CD DVD BD l = 650 nm NA = 0.6 4.7 GBytes l = 405 nm NA = 0.85 22.5 GBytes 0.65 GByte 4.7 GByte 25 GByte 1.2 mm substrate 0.6 mm substrate 0.1 mm substrate

  5. Outline • Introduction • TwoDOS Concept • Write-Channel • Signal-Patterns • Read-Out and Test-Player • Modulation Encoding • Signal Processing and Bit-Detection • Experimental Results • Conclusion

  6. OneDOS – Concept Disc Readout Single Spiral (spiral contains 11 bit-rows)

  7. TwoDOS – Concept Disc Readout (spiral contains 11 bit-rows)

  8. TwoDOS – Concept (2) Signal processing 1D:Conventional Situation upper track = noise central track Signal= lower track = noise radial cross talk isnoise

  9. TwoDOS – Concept (3) Signal Processing 2D: use information adjacent bits upper track = information central track Signal= lower track = information radial cross talk isinformation

  10. TwoDOS – Concept (4) squeeze track-pitch 2D “Joint Detection” • exploit FULL 2D energy-per-bit • use a continuous 2D bit-lattice • 2D hexagonal lattice is optimum (15% higher packing fraction than square lattice)

  11. Effect of “Joint 2D Bit-Detection” Abstracted 2D Impulse-Response (IRF) (for 2D Linear Channel) “tangential” energy : 60% “radial” energy : 40% taps 2D IRF

  12. TwoDOS – Targets • Data-Rate : BD x 10 => 300 Mb/sec • Capacity : BD x 2 => 50 GB(single-layer 12cm disc) at SAME “physics” of BD  blue laser (=405nm)  lens with high numerical aperture (NA=0.85)

  13. Outline • Introduction • TwoDOS Concept • Write-Channel • Signal-Patterns • Read-Out and Test-Player • Modulation Encoding • Signal Processing and Bit-Detection • Experimental Results • Conclusion

  14. Pit-Hole Mastering pit-bit land-bit b pit-depth a circular pit-hole

  15. Outline • Introduction • TwoDOS Concept • Write-Channel • Signal-Patterns • Read-Out and Test-Player • Modulation Encoding • Signal Processing and Bit-Detection • Experimental Results • Conclusion

  16. Clusters on Hexagonal Lattice guard band guard band

  17. Signal-Patterns Phase-1 / Phase-2 a = 165nm a = 138nm Phase-1 : 1.4x BD Phase-2 : 2.0x BD Signal Amplitude “overlap area” • “closed” eye => 2D PRML

  18. Outline • Introduction • TwoDOS Concept • Write-Channel • Signal-Patterns • Read-Out and Test-Player • Modulation Encoding • Signal Processing and Bit-Detection • Experimental Results • Conclusion

  19. Test-Player : Set-Up • binary grating 11 read-out spots • 11 spots photo-detector

  20. Outline • Introduction • TwoDOS Concept • Write-Channel • Signal-Patterns • Read-Out and Test-Player • Modulation Encoding • Signal Processing and Bit-Detection • Experimental Results • Conclusion

  21. Worst-Case Patterns - - + + + - - + + + + - - + + “+” cluster + - - + + + - + - - - - + - - + + + - + - + - - - aH d = 3 aH + - + - - - + - - - - + - - + + - - - + - - + d = 1.5 aH aH “-” cluster 2nd more critical pattern similar to Nyquist-patterns in 1D (MTR-constraint) +-+-+-+- diagonal lattice-planes

  22. 2D Nyquist Cell in 2D Frequency Space : frequency of periodic super-structure of bits beyond MTF cut-off : frequency of diagonal lattice-planes at MTF cut-off 2D-MTF 2D Frequency Space MTF

  23. Super-Structures 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 3 orientation-variants 2 clusters or (opposite polarity) :

  24. => constant signal-amplitude over large area

  25. Partitioning of META-Spiral : Strips and Rows 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 META-spiral : prohibit formation of critical pattern 3-row strip “merging” bit-row 3-row strip “merging” bit-row 3-row strip META-spiral

  26. Need for “Merging Bit-Rows” (1) ... ... ... ... strip “1” strip “2” 3-row areas at boundary => code violations at the boundaries

  27. Need for “Merging Bit-Rows” (2) ... ... ... ... strip “1” “merging row” strip “2” => satisfy 2D constraint at strip-boundaries

  28. Building Blocks for 2D Code and Format ... ... ... ... ... ... 2D 2D - - encoded sub encoded sub - - strip strip ... ... ... 1D 1D - - encoded bit encoded bit - - row row ... ... ... ... ... ... DC-control 11-row META-spiral DC-control DC-control

  29. Coding for the 3-row Strips (1) 0 0 1 1 0 0 ... “fish-bone” 8-ary symbol NRZ symbol x u a b c a x u y v 1T-precoder z w x=u if a=0 x=1-u if a=1 NRZI symbol NRZI symbol

  30. Coding for the 3-row Strips (2) Example NRZ symbol 0 1 1 1 0 1 0 0 0 NRZI symbol NRZI symbol (3) 2 3

  31. Coding for the 3-row Strips (3) States for STD • based on NRZI-symbols • one state for two polarities 8-ary NRZ symbols • 0, 1, ..., 7

  32. Coding for the 3-row Strips (4) “Trivial” STD : no constraints.

  33. Coding for the 3-row Strips (5) ELIMINATION 0 0 1 1 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 0 1 1 Mechanism for Generation of Critical Pattern ... ... (2) (5) (7) NRZ NRZ NRZ 1T-precoder for each bit-row NRZI symbol NRZI symbol NRZI symbol NRZI symbol

  34. “Worst-Case Pattern” build up (1) allow maximum TWO “fish-bones” of “worst-case pattern”

  35. “Worst-Case Pattern” build up (2)

  36. “Worst-Case Pattern” build up (3) => allow maximum TWO “fish-bones” of “worst-case pattern”

  37. State-Transition Table

  38. Connection Matrix 5 6 7 • Channel Capacity

  39. k - constraint 0 0 0 0 1 1 1 1 1 1 1 1 NRZ NRZ NRZ 0 0 0 => maximum k successive 0-symbols : emission of 0-symbol

  40. k - constraint : k = 1 D=

  41. k - constraint : k = 2 D=

  42. Code for 3-row Strips with k=2 0 0 1 1 0 0 153 = 3 * 51 => one Code-Word comprises 51 “fish-bones” ... 51

  43. Code for 3-row Strips : DC-control (1) 0 0 0 0 1 1 1 1 0 0 0 0 DC-control (radial-servo) Merging “Fish-Bone” PURPOSE DC-control (focus-servo) • DC-control • return to state 1 before start of next word DC-control (radial servo) 1 1 ... ... 51 51

  44. Code for 3-row Strips : DC-control (2) NRZ 1 1 ... ... 0 1 1 1 0 0 1 1 1 NRZ 0 0 1 0 ... ... 0 0 1 0 1 Choice-1 Choose according to Running-Digital-Sum of selected Bit-Row Choice-2

  45. Code for 3-Row Strip ... ... “Fish-Bone” 2D Code for 3-row Strip • DC-control with one additional fish-bone :Code Rate : (152 => 153+3) => R = 0.974 • high-rate code 152 -to- 153 Mapping  Enumerative Coding for M-ary symbols (M=8)  issue of Error-Propagation  reverse order ECC and Modulation Code  Bliss-like scheme (see later)

  46. Code for “Merging Bit-Rows” (1) ... ... ... ... strip “1” 0 1 0 0 “merging row” 1 0 0 1 0 0 1 0 0 strip “2” => satisfy 2D constraint at strip-boundaries

  47. Code for “Merging Bit-Rows” (2) 1 0 1 9 7 8 0 0 1 0 0 0 0 0 3 1 2 4 5 6 1 1 1 1 1 • forbidden patterns (NRZI, bipolar) :... 00100100100100 ... and • ... 11011011011011 ... • prohibit 11011 -sequences in NRZ bitstream • 1D code rate 12->13 0110110110110 NRZ

  48. Channel Data-Block 153+3 channel bits => 152 user bits => 19 Bytes 19B 6B 19B 52 channel bits => 4 channel words (13 bit)=> 6 Bytes 6B 19B 52 bits / fish-bones

  49. Bliss-scheme 1D-case (encoder)

  50. Bliss-Scheme for 2D Fish-Bone Code (1)