摘要:
The present invention discloses a decoding path selection device for decoding codewords generated by convolutional codes or turbo codes encoders in error correction codes, the decoding path selection device comprising: a branch metrics calculation unit for receiving incoming signals and calculating branch metrics values; a programmable generalized trellis router for generating a decoding path control signal according to the turbo code or convolutional code specification employed by one of communications standards; a multiplexer for receiving the branch metrics values from the branch metrics calculation unit and the decoding path control signal from the programmable generalized trellis router and selecting a corresponding branch metrics value; a recursive calculation unit, connected after the multiplexer and for receiving the corresponding branch metrics value from the multiplexer; and an a-posteriori probability calculation unit, connected after the recursive calculation unit and for calculating a final decoding result.
摘要:
Methods and apparatuses are provided for operating a list Viterbi decoder. A path metric difference (PMD) threshold is set based on an input signal level and a PMD limit value. Decoding is performed by using the PMD threshold. Performing the decoding includes determining a PMD of a best path, comparing the determined PMD and the PMD threshold, and declaring a decoding failure and ending performing of the decoding, if the PMD is greater than or equal to the PMD threshold.
摘要:
Various embodiments relate to the production of erasure flags to indicate errors resulting from decoding of convolutional codes. A Viterbi decoder may use a register exchange method to produce a plurality of survivor codes. At a defined index, a majority vote may take place comparing values of bits in each of the survivor codes. This majority vote may involve obtaining both the quantity of high-order bits and the quantity of low-order bits and obtaining the difference of the two quantities. The absolute value of the difference of high-order bits to low-order bits may be compared to a defined threshold. When the absolute value difference is below the defined quantity, an erasure flag may be produced and associated with the bits of the defined index, indicating that they are eligible for erasure. In some embodiments, a Reed-Solomon decoder may use the erasure flag to target specific survivor bits or survivor bytes for error-correction through erasure.
摘要:
Variable modulation within combined LDPC (Low Density Parity Check) coding and modulation coding systems. Variable modulation encoding of LDPC coded symbols is presented. In addition, LDPC encoding, that generates an LDPC variable code rate signal, may also be performed as well. The encoding can generate an LDPC variable code rate and/or modulation signal whose code rate and/or modulation may vary as frequently as on a symbol by symbol basis. Some embodiments employ a common constellation shape for all of the symbols of the signal sequence, yet individual symbols may be mapped according different mappings of the commonly shaped constellation; such an embodiment may be viewed as generating a LDPC variable mapped signal. In general, any one or more of the code rate, constellation shape, or mapping of the individual symbols of a signal sequence may vary as frequently as on a symbol by symbol basis.
摘要:
Various embodiments of the present invention provide systems and methods for sequence detection. As an example, a method for data detection is disclosed that includes: receiving a series of data samples at a detector circuit; multiplying a portion of the series of data samples by a first correlator value corresponding to a first binary transition to yield a first value; multiplying the portion of the series of data samples by a second correlator value corresponding to a second binary transition to yield a second value; adding the first value to a prior state value to yield a first interim value; adding the second value to the prior state value to yield a second interim value; and selecting the larger of the first interim value and the second interim value to yield a surviving interim value.
摘要:
Variable modulation within combined LDPC (Low Density Parity Check) coding and modulation coding systems. A novel approach is presented for variable modulation encoding of LDPC coded symbols. In addition, LDPC encoding, that generates an LDPC variable code rate signal, may also be performed as well. The encoding can generate an LDPC variable code rate and/or modulation signal whose code rate and/or modulation may vary as frequently as on a symbol by symbol basis. Some embodiments employ a common constellation shape for all of the symbols of the signal sequence, yet individual symbols may be mapped according different mappings of the commonly shaped constellation; such an embodiment may be viewed as generating a LDPC variable mapped signal. In general, any one or more of the code rate, constellation shape, or mapping of the individual symbols of a signal sequence may vary as frequently as on a symbol by symbol basis.
摘要:
LDPC (Low Density Parity Check) coded modulation symbol decoding. Symbol decoding is supported by appropriately modifying an LDPC tripartite graph to eliminate the bit nodes thereby generating an LDPC bipartite graph (such that symbol nodes are appropriately mapped directly to check nodes thereby obviating the bit nodes). The edges that communicatively couple the symbol nodes to the check nodes are labeled appropriately to support symbol decoding of the LDPC coded modulation signal. The iterative decoding processing may involve updating the check nodes as well as estimating the symbol sequence and updating the symbol nodes. In some embodiments, an alternative hybrid decoding approach may be performed such that a combination of bit level and symbol level decoding is performed. This LDPC symbol decoding out-performs bit decoding only. In addition, it provides comparable or better performance of bit decoding involving iterative updating of the associated metrics.
摘要:
The use of a multi-track format in both optical and magnetic data storage applications provides for a number of improvements to system performance including data density and data transfer rates. However, the full advantage in data density can only be achieved through the use of joint equalization and joint detection. The complexity of implementation of these functions arc addressed with a transform domain equalization architecture and a reduced complexity detection method based on a breadth first search of a time-varying trellis. The trellis results from a one dimensional representation of a two dimensional target response, obtained by arranging samples from adjacent tracks in a sequence that respects the original proximity of the samples.
摘要:
The disclosed technology provides systems and methods for identifying potential error locations, patterns, and likelihood metrics in connection with trellis-based detection/decoding. In one aspect of the invention, the disclosed technology detects information that was previously encoded based on a trellis, and decodes the detected information based on the trellis to provide decoded information. The decoded information corresponds to a winning path through the trellis that ends at a winning state. The disclosed technology can identify one or more alternate paths through the trellis that also end at the winning state, and can generate a potential error pattern for each of the alternate paths.
摘要:
The disclosed technology provides systems and methods for identifying potential error locations, patterns, and likelihood metrics in connection with trellis-based detection/decoding. In one aspect of the invention, the disclosed technology detects information that was previously encoded based on a trellis, and decodes the detected information based on the trellis to provide decoded information. The decoded information corresponds to a winning path through the trellis that ends at a winning state. The disclosed technology can identify one or more alternate paths through the trellis that also end at the winning state, and can generate a potential error pattern for each of the alternate paths.