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Signal, storage medium, method and device for encoding, method and device for decodingRelated Patent Categories: Error Detection/correction And Fault Detection/recovery, Pulse Or Data Error Handling, Digital Data Error CorrectionSignal, storage medium, method and device for encoding, method and device for decoding description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070011551, Signal, storage medium, method and device for encoding, method and device for decoding. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The invention relates to a signal comprising a runlength limited (RLL) encoded binary d,k channel bitstream, wherein parameter d defines a minimum number and parameter k defines a maximum number of zeroes between any two ones of said bitstream or vice versa, comprising a number of sections of respectively N successive RLL channel bits, called RLL rows, each RLL row representing a parity-check code-word, called row parity-check code-word, in which a so-called row-based parity-check constraint for said RLL row has been realized. [0002] Furthermore, the invention relates to a storage medium comprising such a signal. [0003] Furthermore, the invention relates to a method for encoding a stream of user data bits comprising the step of runlength limited (RLL) encoding said stream of user data bits into a binary d,k channel bitstream comprising a number of sections of respectively N successive RLL channel bits, called RLL rows, wherein parameter d defines a minimum number and parameter k defines a maximum number of zeroes between any two ones of said bitstream or vice versa, each RLL row representing a parity-check code-word, called row parity-check code-word in which a so-called row-based parity-check constraint for said RLL row has been realized. [0004] Furthermore, the invention relates to a corresponding device according to the preamble of claim 33. [0005] Furthermore, the invention relates to a method for decoding such a signal or a signal being encoded according to such a method for encoding. [0006] Furthermore, the invention relates to a device for decoding such a signal or a signal being encoded according to such a method for encoding. [0007] In the field of mass data storage media, such as optical discs, magnetic discs and magneto-optical discs, digital surface recorders are used that are substantially narrow bandpass signaling devices. Therefore, the data to be recorded on such media is encoded such, to eliminate very long as well as very short written pits. This encoding is called "modulation coding". It typically employs a runlength limited (RLL) code which is characterized by two parameters, namely the constraints d,k, wherein d.ltoreq.k. RLL-encoded binary sequences have at least d, but no more than k zeroes between any two ones. Transitions between written pits correspond to occurrences of ones. A one in the binary d,k channel bitstream corresponds to a transition between e.g. pit and land (wherein "land" defines the space between two pits). Thus, the minimum-length pit or land consists of d+1 channel bits and the maximum-length land or pit consists of k+1 channel bits. [0008] FIG. 1 shows a bitstream of un-constrained user data 1 that are RLL encoded 2 with d,k constraints and a code rate R=m/n. Thus, an NRZ or d,k channel bit stream 3 is obtained, in which the ones represent transitions from pit to land or vice versa. [0009] An RLL waveform 4 is recorded on a storage medium, e.g. a disc, by using lands and pits. Whenever a "1" occurs in the d,k channel bitstream 3, the RLL waveform 4 performs a transition from land to pit or vice versa. Thus, pits and lands both represent strings of zeroes of varying length, each string being preceded by a one-bit which indicates the transition between them, so that the length of a run of bits of the same polarity (pit or land) equals the number of zeroes plus one. [0010] One of the major error sources during read-out of such a disc are random errors, due to imperfections in deriving the d,k channel bitstream from the HF (high-frequent) signal waveform. For the case of a perfect channel (without any intersymbol-interference or ISI) this waveform equals to RLL waveform 4 which is the waveform directly generated from the bipolar channel bitstream (with values equal to either +1 or -1). However, the actual HF waveform in case of a realistic channel in the presence of (linear and/or non-linear) ISI is a rounded version of RLL waveform 4, with lower amplitude at shorter runlengths, according to the eye-pattern. This actual HF-waveform is used for bit-detection, and here so-called "single-bit transition-shift errors" (SBTSE) can be made. [0011] Random errors (in the optical recording channel) most often lead to a shift of a transition ("1"-bit in the d,k channel bitstream) over a distance of a single bit. A corresponding error event 5 is depicted in the channel bitstream 6 that is detected from the actual HF waveform. This error event 5 results in a shift of the transition from the first land to the second pit over a distance of a single bit. Such an error event 5 is a SBTSE. In the detected (erroneous) d,k bitstream 7 such a SBTSE results in a shift of a "1" over a distance of one bit. [0012] For random errors of this specific type, it is advantageous not to use the standard error correction coding (ECC) with algebraic Reed-Solomon error-correcting codes since the latter requires two user bytes (called parity-bytes) of overhead for correction of a single random error (one parity-byte for location of the error and one parity-byte for correction of the byte-value). [0013] Instead, specifically designed parity-check RLL codes can be used to detect the presence of such a random error, and channel side-information, like the magnitude of phase-errors generated at each transition of the HF waveform in a PLL, can be used to locate the error. [0014] Several proposals for such parity-check RLL coding have been made, such as in H. M. Hilden, D. G. Howe, E. J. Weldon, "Shift Error Correcting Modulation Codes", IEEE Trans. Magn., vol. 27, 1991, pp. 4600-4605; Y. Saitoh, I. Ibe, H. Imai, "Peak-Shift and Bit Error-Correction with Channel Side Information in Runlength-Limited Sequences", 10th Int. Symp. Applied Algebra, Algebraic Algorithms and Error-Correcting Codes, vol. AAECC-10, 1993, pp. 304-315; P. Perry, M.-C. Lin, Z. Zhang, "Runlength-Limited Codes for Single Error-Detection with Mixed Type Errors", IEEE Trans. Inform. Theory, vol. 44, 1998, pp. 1588-1592; S. Gopalaswamy, J. Bergmans, "Modified Target and Concatenated Coding for d=1 Constrained Magnetic Recording Channels", Proceedings of the ICC 2000, New Orleans, Jun. 18-22, 2000; and H. Sawaguchi, M. Kondou, N. Kobayashi, S. Mita, "Concatenated Error Correction Coding for High-Order PRML Channels", Proceedings of Globecom 1998, Sidney, pp. 2694-2699. [0015] Furthermore, one of the inventors of the present invention published the idea to use so-called combi-codes for parity-check RLL coding, in: W. M. J. Coene, H. P. Pozidis, J. W. M. Bergmans, Title: "Run-Length Limited Parity-Check Coding for Transition-Shift Errors in Optical Recording", Proceedings of Globecom 2001, Paper SPS01.sub.--6, San Antonio (USA), Nov. 25-29, 2001. [0016] In the latter reference it was shown that for the case of a single SBTSE the overhead for random-error correction was reduced to a single user-bit, with error-location handled via channel side-information, and disadvantages of previous schemes for parity-check RLL coding have been eliminated. [0017] The procedure to use channel side-information for SBTSE is to search among all transitions that are detected and used in the phase-locked loop (PLL) for the purpose of timing-recovery, for the transition that has the phase-error with the largest absolute value and then shift backwards the corresponding transition (or "1"-bit) in the d,k channel bitstream. However, this procedure may not be 100% full-proof: there can also be large phase-errors that correspond to error-free transitions, quantization of phase-errors may have an effect, etc. [0018] Therefore, it is an object of the present invention to provide an alternative way for error-location, where the need to use channel side-information is avoided, or at least, reduced considerably. [0019] This object is achieved by a signal comprising an RLL encoded binary d,k channel bitstream according to the above-mentioned type characterized in that K sections of respectively N successive channel bits, called column parity-check rows, are located at predetermined positions of a group of M RLL rows, K, N and M being integer values, said column parity-check rows comprising a plurality of column parity-check enabling channel words, wherein each of said column parity-check enabling channel words realizes a so-called column-based parity-check constraint for all so-called corresponding segments of at least said M RLL rows of said group that correspond to a specific column parity-check enabling channel word, and constitute together with said column parity-check enabling channel word the column parity-check codeword. [0020] The object is further achieved by providing a storage medium storing such a signal. [0021] The object is further achieved by providing a method for encoding a stream of user data bits according to the above-mentioned type characterized by the further step of: generating K sections of respectively N successive channel bits, called column parity-check rows, at predetermined positions of a group of M RLL rows, K, N and M being integer values, said parity-check rows comprising a plurality of column parity-check enabling channel words, wherein each of said column parity-check enabling channel words realizes a so-called column-based parity-check constraint for so-called corresponding segments of at least said M RLL rows of said group that correspond to a specific column parity-check enabling channel word, and constitute together with said column parity-check enabling channel word the column parity-check codeword. [0022] The object is further achieved by providing a corresponding device for encoding a stream of user data bits according to claim 33. [0023] Furthermore, the object is achieved by a method for decoding a signal being encoded according to such a method for encoding a stream of user data bits according to claim 35. [0024] Furthermore, the object is achieved by a corresponding device according to claim 47 for decoding a signal being encoded according to such a method for encoding a stream of user data bits. Continue reading about Signal, storage medium, method and device for encoding, method and device for decoding... Full patent description for Signal, storage medium, method and device for encoding, method and device for decoding Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Signal, storage medium, method and device for encoding, method and device for decoding patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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