摘要:
A method and apparatus for multi-level encrypted encoding and decoding of digital signals, which includes utilizing only one type of encoder and one type of decoder. This can be either the same encoder and decoder used in throughout the process, or multiple, identical encoders and decoders. This allows the system to compensate for atmospheric degradation with higher bandwidth efficiency and a simplified receiver structure. The invention further identifies a 2j symbol generation technique that maps in disjoint regions of X-dimensional space, which allows different data bits to be eliminated from the decoding scheme and maximizes the number of independent data substreams that can be maintained.
摘要:
The present invention performs decoding of trellis coded modulated data using a conventional decoder by splitting up the tasks of estimating the uncoded portion and estimating the coded portion into separate tasks. The task of estimating the coded portion is performed based on a transformation on the input symbols and by taking advantage of the symmetry of the constellation associated with the modulated data when referencing a lookup table. The lookup table may also be designed to be smaller than a straight forward implementation by taking advantage of the same symmetry of the constellation.The alteration of the data is then corrected for, resulting in a smaller constellation (Bi Phase Shift Key for 1 coded bit per symbol systems, Quadrature Phase Shift Key for 2 coded bits per symbol systems) mapping only the coded portion of the data. This allows a conventional Viterbi decoder to estimate the coded portion. The task of estimating the uncoded portion of the data is then performed by using information about the sector of the constellation of the original data along with a re-encoded version of the estimated coded portion.
摘要:
A method and apparatus for fast decoding of a Reed-Solomon codeword which includes storing the codeword in memory, finding syndromes of the codeword, using the syndromes to determine the number of errors in the codeword, which in turn are used to find an error locator polynomial for the codeword, which is a polynomial whose roots can be used to find the locations of the errors. This error locator polynomial is then be used to find the positions of the errors in the codeword. The positions of the errors in the codeword can be used along with the syndromes to determine the values of the errors in the codeword.
摘要:
A Reed-Solomon decoder capable of correcting two symbol errors in a codeword of a Reed-Solomon RS(128,122,7) code over a Galois field GF(128) is provided. In an exemplary embodiment, the Reed-Solomon decoder is suitable for use in cable modems with little or no loss in error performance over Reed-Solomon decoder correcting three errors in a codeword.
摘要:
The purpose of the present invention is to provide a method for choosing the coding schemes, mappings, and puncturing rates for a modulation/demodulation system which would allow the system to compensate for certain transformations of the code in a post-Viterbi step as opposed to pre-Viterbi. This would allow for faster and simpler decoding of a code. The method includes the steps of: choosing a coding scheme and puncturing rate; determining a code generator matrix using said coding scheme and puncturing rate; multiplying the code generator matrix by the transformation matrix by the code generator matrix's feedback free right inverse and seeing if the outcome is equal to the code generator matrix multiplied by the transform matrix; multiplying the error matrix by the code generator matrix's feedback free right inverse by the code generator matrix and seeing if the outcome is equal to the error matrix; repeating all the steps until a code generator matrix that satisfies said invariancy equations is found; and choosing a mapping scheme that takes advantage of the invariancy.
摘要:
A transmitter, the method of the same, and a communication system using the scheme of space-time block coding employing the multiple beams to mitigate the multipath fading. A transmitter constituted array antennas first performs beams scanning employing beamforming network for estimating the channel space gain pattern, then estimates number of the beams for transmission and the corresponding angles of each beam, performs beam space-time block encoding of input signals then transmitting the encoded signals. The receiver receives the signal and performs linear channel decoding, for example, maximum likelihood decoding.
摘要:
A modulation format identification device capable of realizing a practical receiver capable of identifying a modulation format of a received signal irrespective of its modulation format by a simple configuration, wherein provision is made of a phase lock detector group having a plurality of detectors provided corresponding to a plurality of modulation formats and with the received signals input in parallel thereto, counting a number of symbols in accordance with the modulation format for every detector, making a primary decision that the received signal has been modulated by the related modulation format when the count exceeds a constant threshold value, and outputting the results as lock detection flags and a logic circuit for exclusively selecting one modulation format upon receipt of the plurality of output results of the phase lock detector group, and a method of the same.
摘要:
A decoder for performing soft decision iterative decoding of a cyclic code based on belief propagation, includes an information exchange control unit, an X processor, and a Z processor. The information exchange control unit takes &pgr;x-metrics that were calculated by the X processor for nonzero elements in each of n-cyclic shifts of the parity-check polynomial of the code, and distributes the &pgr;x-metrics to the Z processor as the &pgr;z-metrics for a corresponding check node. The information exchange control unit takes &lgr;z-metrics that were calculated by the Z processor for nonzero elements in each of n-cyclic shifts in a reverse order of the parity-check polynomial, and distributes them to the X processor as &lgr;x-metrics for the corresponding code node. The operation of the information exchange control unit can be represented by the Tanner graph associated with an extended parity-check matrix, which is produced by adding k rows to the parity-check matrix of the cyclic code.
摘要:
A plurality of circuit cells, a plurality of matrix switch sections and a plurality of switch sections for connecting between the plurality of circuit cells, all of which form a part of a circuit cell array, and a plurality of input/output cell sections arranged around the circuit cell array all change their circuit configurations in accordance with a configuration data to be supplied. In some of these circuit blocks, at least a part of the circuit thereof is fixed at a predetermined circuit configuration, and a conversion of the configuration data based on proprietary information regarding the fixed circuit is performed at a supplier of the configuration data. Thus, a differential configuration data for portions of the circuit other than the fixed circuit portion is generated and supplied to the integrated circuit.
摘要:
The present invention is directed to the encoding and decoding of a digital signal. The encoding process results in a rate-1/n convolutional code derived from a rate-1/2 convolutional code. The process includes: selecting a base convolutional encoding rate of rate-1/l, where l is an integer; selecting an output encoding rate of 1/n, where n is an integer greater than 1; encoding an input digital signal into a convolutional code comprised of signals S(0) through S(l-1), the convolutional code having the rate 1/l convolutional code encoding rate; and providing a rate-1/n convolutional code, which is derived from the rate-1/l convolutional code, the rate-1/n convolutional code having N(i) copies of the rate-1/l signals S(i), where i is from 0 through 1-l and where the sum of N(i) is equal to n. The decoding process results in a digital signal estimated from received symbols which include rate-1/n convolutional code generated by the above encoding process and any noise that may have been introduced by a transmission medium. The process includes the step of: generating a signal pair from the received symbols, the signal pair having a first signal and a second signal which are suitable for decoding by a rate-1/2 convolutional decoder. The first signal is an average of a sum of encoded signals which correspond to positions in the rate-1/2 convolutional code encoded using a first generator polynomial. The second signal is an average of a sum of encoded signals which correspond to positions in the rate-1/n convolutional code encoded using a second generator polynomial. The method also includes a step of decoding the signal pairs using a rate-1/2 convolutional decoder.