DC-free Runlength-limited Codes Research Articles

A new DC-free multimode code design with error correction capability for optical storage systems

DC-free run-length limited codes have been the cornerstone of all three generations of optical recording, CD, DVD and BD. Research into efficient coding methods is paramount for the upcoming fourth generation. A Multimode coding technique is an efficient coding method that has been reported in the literatures. Under multimode coding rules, a user word is translated into a plurality of possible candidate words, and among the candidate words the encoder selects the codeword with the least low-frequency spectral content. In our paper, we will present a new coding technique for constructing error correcting high-rate DC-free multimode code using a low-density parity-check (LDPC) code for future high-density optical recording. The scheme achieves reliable DC-suppression and obtains considerable bit error rate (BER) performance gain through the iterative decoding (or turbo equalization) with the concatenated detector.

Construction of Constrained Codes for State-Independent Decoding

Constrained sequence codes are widely used to meet constraints imposed by digital storage and communication systems. This paper develops an algorithm for the construction of constrained codes that admit state-independent decoding. By partitioning the code into a group of alphabets, one for each state, a codebook is developed using this algorithm that will allow the code to be decoded at the receiver without the need for state information. Finally, we use this algorithm to construct DC-free runlength-limited (RLL) codes, and we present two highly efficient state-independent decodable DC-free RLL codes.

DC-free multimode code design using novel selection criteria for optical recording systems

DC-free run-length limited codes have been the cornerstone of all three generations of optical recording, CD, DVD and BD. Research into very efficient coding methods is paramount for the upcoming fourth generation. Guided Scrambling (GS) is an efficient coding method that has been reported in the literature. Under GS rules, a user word is translated into a plurality of possible candidate words, and among the candidate words the encoder selects the codeword with the least low-frequency spectral content. In our paper, we will present results of our attempts to improve the performance of GS-based codes. We will present new selection criteria and evaluate their performance and complexity. Specifically, we will evaluate the new selection criteria to the 2/3(1,7) parity preserving code used in Blu-Ray Disc.

Efficient dc-free RLL codes for optical recording

We report on new dc-free runlength-limited codes (DCRLL) intended for the next generation of DVD. The efficiency of the newly developed DCRLL schemes is extremely close to the theoretical maximum, and as a result, significant density gains can be obtained with respect to prior art coding schemes. With a newly developed DCRLL (d=2) code we can achieve a 9% higher overall rate than that of DVD's EFMPlus.

Construction of Efficient Dc-Free Runlength-Limited Codes for Optical Recording

We will report on new dc-free runlength-limited codes (DCRLL) intended for the next generation of digital versatile disc (DVD). The efficiency of the newly developed DCRLL schemes is extremely close to the theoretical maximum, and as a result, significant density gains can be obtained with respect to prior art coding schemes. Preferred embodiments of the codes (footprints) and respective hardware realization will be considered.

Extremely efficient DC-free RLL codes for optical recording

We report on new DC-free runlength-limited codes (DCRLL) intended for the next generation of DVD. The efficiency of the newly developed DCRLL schemes is extremely close to the theoretical maximum, and as a result, significant density gains can be obtained with respect to prior art coding schemes.

Combi-codes for DC-free runlength-limited coding

We present a new coding scheme for DC-free runlength-limited (RLL) codes. This scheme is based on the combination of two codes, a main code and a substitution code, both operating on symbols of a fixed length n. The substitution code has a special structure, i.e., for each n-bit symbol, there are two possible channel words, which have opposite parity and the same next-state in the underlying finite-state machine (FSM). The advantages of this systematic structure of the code are: guaranteed DC-control, ECC-symbol oriented coding, and low-complexity look-ahead DC-control encoding. A design for an efficient combi-code for both for EFM-like RLL constraints (d=2, k=10) and for (d=1, k=7) RLL constraints, is outlined.