154results about "Error correction/detection using multiple codes" patented technology

In bus communications methods and apparatus, a first set of physical signals representing the information to be conveyed over the bus is provided, and mapped to a codeword of a spherical code, wherein a codeword is representable as a vector of a plurality of components and the bus uses at least as many signal lines as components of the vector that are used, mapping the codeword to a second set of physical signals, wherein components of the second set of physical signals can have values from a set of component values having at least three distinct values for at least one component, and providing the second set of physical signals for transmission over the data bus in a physical form.

A method of concatenation for LDPC encoding in an OFDM wireless system selects codewords based on the data packet payload size, wherein the payload size is the number of transmitted information bits in octets. For low transmission rates, shortening and puncturing across all codewords within the packet is applied to minimize OFDM symbol padding. For high transmission rates, only shortening across all codewords within the packet is applied to minimize OFDM symbol padding.

Provided is an apparatus and method for transmitting / receiving data in a communication system using a structured Low Density Parity Check (LDPC) code. The transmitter performs structured LDPC coding on input information data using a structured LDPC code, parallel-converts a structured LDPC codeword generated by performing the structured LDPC coding, in units of groups having a predetermined size, and transmits data. The receiver receives a plurality of parallel data streams, serial-converts the received parallel data streams in units of groups having a predetermined size, and performs structured LDPC decoding on the data which was serial-converted group by group, using a structured LDPC code.

A digital modulator which inputs a data stream to convert to a channel bit stream. The multiplexed data block is generated by multiplexing dummy data to any position within each data block cut out of the data stream one by one. The first Reed-Solomon code is generated by Reed-Solomon-encoding the multiplexed data block as an information part. A plurality of second Reed-Solomon codes are generated by adding a plurality of Reed-Solomon codes for scrambling each of which has identification data showing its scrambling pattern in the same position as that of the dummy data, and the code length of information part and parity part is the same as the first Reed-Solomon code. The second Reed-Solomon code in which the characteristics becomes desirable after modulation among the plurality of the second Reed-Solomon codes is set for output.

Apparatus, and an associated method, for allocating communication data for communication in a multi-channel communication system, such as an OFDM system. An adaptive bit, power, and code rate scheme for a sending station that utilizes LDPC codes selects together bit, power, and code rates of data that are to be communicated upon different ones of the channels in manners that optimize a selected performance criteria.

Disclosed is a method and communication device for suppressing interference. The method comprises performing, with a turbo decoder (314), at least one turbo decoding attempt (1106) on a received signal (1104). The turbo decoding attempt generates at least one whole word code bit therefrom (1108). The whole word code bit (1108) corresponds to a group of bits comprising a transmitted symbol. The method determines if the whole word code bit (1108) has a confidence level exceeding a given threshold (1110). If the whole word code bit (1108) does have a confidence level exceeding the given threshold, the whole code word bit is selected for use in data symbol recovery (1114).

A system and method are provided for transferring a packet across a data link. The packet may include a stream of data symbols which is delimited by one or more framing symbols. Corruptions of the framing symbol which result in valid data symbols may be mapped to invalid symbols. If it is desired to transfer one of the valid data symbols that has been mapped to an invalid symbol, the data symbol may be replaced with an unused symbol. At the receiving end, these unused symbols are replaced with the corresponding valid data symbols. The data stream of the packet may be encoded with forward error correction information to detect and correct errors in the data stream.

In this invention a thirty three bit word is encoded from a thirty two bit word to conform to RLL coding constraints. A parity bit is added to the coded word after coding is complete. With the parity bit inserted the code satisfies a minimum Hamming weight of nine and no more than eleven consecutive zeros and no more than eleven consecutive zeros in both the odd and even interleaves. A table of "bad" eight bit sequences is used to compare the odd and even interleaves of the right and left halves of the input word that is being encoded. If a "bad" sequence is found, its position in the table points to a second table containing a four bit replacement code that is inserted into the coded output word. Flag bits in the output coded word are set to indicate the violation of the coding constraints and provide a means by which a decoder can be used to reverse the process and obtain the original input word.

An Orthogonal Frequency Division Multiplexing (OFDM) communiation system and method for improving frequency utilization efficiency. In the system, a Reed-Solomon encoder codes input information data, and ouputs a Reed-Solomon block having a second number of Reed-Solomon symbols, each Reed-Solomon symbol having a first number of Reed-Solomon symbol elements. An interleaver receives the Reed-Solomon block, and disperses the Reed-Solomon symbol elements existing in a specified one Reed-Solomon symbol within the received Reed-Solomon block in the same sub-channel position in a fourth number of sub-channels of each of a third number of consecutive OFDM symbols.

A system, an apparatus and a method for transmitting / receiving data coded by a low density parity check matrix code are provided. The apparatus for transmitting data coded by a low density parity check code includes: a low density parity check encoder for encoding input data based on the low density parity check code; and a bit puncturer for puncturing columns in an order of columns which least degrade a performance caused by puncturing in the low density check code according to a code rate of an output data. Accordingly, the low density parity check code having superior performance can be implemented to the next generation mobile communication system supporting various code rates.

A method of combining spectral shaping with turbo coding in a channel coding system. The method comprises encoding user data with spectrally shaped encoding to provide a suppressed DC user data sector output. The method also comprises generating turbo coded redundant bits for the suppressed DC user data sector. The turbo coded redundant bits are interleaved with additive coding to provide a suppressed DC parity sector.

A system and method for encoding a sequence of 32 bit digital data words into a sequence of 33 or more bit codewords having constraints of (d=0, G=9 / I=9) for recording upon a magnetic medium within a magnetic recording channel are disclosed. The method includes dividing each 32 bit digital data word into three 8-bit bytes and another 8-bit byte, expanding the another 8-bit byte into a 9-bit word, dividing the 9-bit word into three 3-bit subparts, forming three 11-bit intermediate blocks, each comprising one of the three 3-bit subparts and one of the three 8-bit bytes, encoding each of the three 11-bit intermediate blocks to generate three 11-bit encoded words, and forming each codeword from a set of the three 11 -bit encoded words. The set of the three 11-bit encoded words satisfies a predetermined minimum zero run length (d) constraint, a predetermined maximum zero run length (G) constraint, and a predetermined maximum interleave zero run length (I) coding constraint.

A Hamming weight encoder includes an input that receives user data including P symbols and a Hamming weight module that determines a Hamming weight of N of said P symbols. N and P are integers greater than one and N is less than or equal to P. The Hamming weight encoder also includes a comparing module that compares the Hamming weight to a Hamming weight threshold and an inverting module that selectively bitwise inverts bits in said N symbols based on said comparison.

A system and method for Reverse Error Correction Coding. The system includes a Constraint encoder, an Error Correction Code encoder, and a uniform interleaver. The Constraint encoder receives a source data stream and generates a first intermediate encoded data stream satisfying a first predetermined timing data constraint. The Error Correction Code encoder receives the first intermediate encoded data stream and generates a second intermediate encoded data stream having one or more Error Correction Code based elements. The uniform interleaver receives the second intermediate encoded data stream and generates a channel data stream having the one or more Error Correction Code based elements and satisfying a second predetermined timing data constraint.

A system comprises an encoder, a precoder, a PRML channel, a detector, and a decoder. An input signal is received by the encoder. The encoder generates a code string by adding one or more bits and outputs the code string to the precoder. The encoder applies encoding such that the code string after passing through the precoder has a Hamming distance greater than one to eliminate error events with a small distance at the output of the PRML channel. The present invention also provides codes that after precoding have Hamming distance of 2 and 0 mod 3 number of ones. These codes when used over a PRML channel in an interleaved manner preclude + / -( . . . 010-10 . . . ) error events and error events + / -( . . . 01000-10 . . . ). The code string also has a predetermined minimum number of ones at the output of the PRML channel to help derive a clock from the input signal. The encoder provides a "systematic" encoding scheme in which for many code strings the encoded bits are the same as the input bits used to generate the encoded bits. This systematic approach of the present invention provides an encoder that is easy to implement because a majority of the bits directly "feed through" and non-trivial logic circuits are only needed to generate the control bits. The systematic encoding also dictates a decoder that is likewise easy to construct and can be implemented in a circuit that simply discards the control bit. The encoder preferably comprises a serial-to-parallel converter, a code generator, and a parallel-to-serial converter. The code generator produces a rate 16 / 18 or 16 / 17 code. The present invention also includes a method that is directed to encoding bit strings and comprises the steps of: 1) converting the input strings to input bits, and 2) adding at least one bit to produce an encoded string with many ones and a Hamming distance greater than one after precoding.

A communication quality is improved or signal processing is simplified in a multi-carrier communication system such as OFDM. Information different in communication quality such as systematic bits and parity bits of turbo encoded code words is combined together, and information that requires a high communication quality such as the systematic bits is mapped to carriers having a frequency close to the carriers in which the pilot signal exists used as a reference phase of demodulation than the information such as the parity bits which does not require the high communication quality such as the systematic bits.

Dislosed is an apparatus and method for erasure detection and soft-decision decoding in a cellular system receiver. In the present invention, a complex channel gain and a noise variance of a received symbol from a cellular system transmitter are estimated, and an erasure symbol (a symbol with high power interference) is detected by comparing a threshold value according to the estimated complex channel gain or noise variance with power of the received symbol. Log-likelihood ratios corresponding to constituent bits of the detected erasure symbols are allowed to be 0, and the log-likelihood ratios of the constituent bits of the other received symbols are calculated. A soft-decision decoding operation of received bits is performed with the calculated log-likelihood ratios.

A transmitter simultaneously performs channel coding and rate matching in a CDMA mobile communication system. The transmitter encoders input bits into coded bits at a given mother code rate, and performs puncturing on the coded bits in order to match the number of coded bits to a predetermined code rate. Thereafter, the transmitter simultaneously performs rate matching for repeating or puncturing the coded bits in order to match the number of coded bits to the number of bits transmitted over a radio channel.

A receiver of COFDM digital television signals includes an inner decoder for iterative soft-decision decoding of concatenated convolutional coding (CCC) and an outer decoder for Reed-Solomon (RS) coding. The receiver generates error flags for identifying code symbols to be erased before the output symbols from the inner decoder are byte de-interleaved and supplied to the outer decoder. Generation of those flags depends on soft decoding results from the inner decoder. The method of locating errors ascribes to each byte supplied to the outer decoder for RS coding the highest lack-of-confidence level specified by the soft data bits associated with that byte. The method is described as being extended to locate byte errors in plural-dimension cross-interleaved Reed-Solomon codes (CIRC) apt to be employed in DTV broadcasting to mobile and handheld receivers.

The present invention relates to a multicarrier direct sequence code division multiple access (DS / CDMA) system using a turbo code with nonuniform repetition coding. In particular, it relates to a multicarrier DS / CDMA system using a turbo code with unequal diversity order in its code symbols instead of using a convolutional code.

An orthogonal frequency division multiplexing (OFDM) communication system and method for improving frequency utilization efficiency. In the system, a Reed-Solomon encoder codes input information data, and outputs a Reed-Solomon block comprised of a second number of Reed-Solomon symbols each comprised of a first number of Reed-Solomon symbol elements. An interleaver receives the Reed-Solomon block, and disperses the Reed-Solomon symbol elements existing in a specified one Reed-Solomon symbol within the received Reed-Solomon block in the same sub-channel positions in a fourth number of sub-channels of each of a third number of consecutive OFDM symbols.

A decoding system for LDPC code concatenated with 4QAM-NR code in a DTMB system is a two-stage decoding system. An NR decoder performs a 4QAM-NR decoding to obtain hard decision information. Then, the so obtained hard decision information together with corresponding soft symbol and channel state information are sent to a log-likelihood ratio (LLR) device for further computing a log-likelihood ratio after an adder adds a correction term associated with the hard decision information to a computed log-likelihood ratio without the hard decision information. An LDPC decoder receives the LLR for decoding.

An orthogonal frequency division multiplexing (OFDM) communication system and method for improving frequency utilization efficiency. In the system, a Reed-Solomon encoder codes input information data, and outputs a Reed-Solomon block having a second number of Reed-Solomon symbols each having a first number of Reed-Solomon symbol elements. An interleaver receives the Reed-Solomon block, and disperses the Reed-Solomon symbol elements existing in a specified one Reed-Solomon symbol within the received Reed-Solomon block in the same sub-channel positions in a fourth number of sub-channels of each of a third number of consecutive OFDM symbols.

The invention discloses a trellis code modulated (TCM) code modulation method, and is to solve the problem of poor entirety of the prior TCM codes. The invention comprises the following steps. Firstly, a square QAM planisphere with the modulation order number larger than 4 is used as a constellation mapping scheme so that after the codes on a way I and a way Q of the constellation mapping scheme are mapped, and bit blocks are arranged repeatedly on a periodic basis on the ways I and Q, and corresponding uncoded bit blocks are different after each repeated arrangement on a periodic basis. Constellation indices including coded bit blocks and uncoded bit blocks are acquired according to original bit message block. Signaling points in the constellation mapping scheme according to the constellation indices are determined as the final emissive TCM signals. As the coded bit blocks are repeatedly arranged on a periodic basis, and corresponding uncoded bit blocks are different from each other, mappings of symbols for parallel paths on the way Q of the constellation mapping scheme are uniform, and the entirety of TCM codes can be improved.

The invention provides a data transmission apparatus, a date sending and receiving apparatus and a data transmission system. The data transmission apparatus includes a packet generation section, a frame encoding section, a transmission section, a reception section, a frame decoding section and a packet extraction section. The packet generation section generates a packet upon request. The frame encoding section generates a frame having a predetermined length by dividing the packet or adding dummy data to the packet and generates an error-correcting-code-added frame by adding an error correcting code to the frame. The transmission section transmits the generated error-correcting-code-added frame through a transmission line. The reception section receives the error-correcting-code-added frame. The frame decoding section performs error detection and an error correction for the error-correcting-code-added frame. The packet extraction section extracts the packet by removing the error correcting code from the error-correcting-code-added frame for which the error detection and the error correction have been performed.

A low density parity check (LDPC) encoder, an LDPC decoder, and an LDPC encoding method are disclosed. The LDPC encoder includes first memory, second memory, and a processor. The first memory stores an LDPC codeword. The second memory is initialized to 0. The processor generates the LDPC codeword by performing accumulation with respect to the second memory using information bits. The accumulation is performed at parity bit addresses that are updated using a sequence corresponding to a parity check matrix (PCM).