995results about How to "Improve decoding performance" patented technology

The invention discloses a density evolution based polarization code constructing method and polarization code coding and decoding system. According to the invention, the code length N and the information bit length K of an information code to be processed are obtained, an expectation value set of a log-likelihood ratio probability density function of N bit channels, K bit channels are selected as the information bit channels according to the expectation value set and information bit information index vector quantity is generated; an information bit sequence and a fixed bit sequence are mixed and the mixed bit vector quantity is multiplied by a polarization code for generating a matrix so as to output an encoding sequence; the encoding sequence is modulated and input into a transmission channel and the sequence output by the transmission channel is subjected to decoding operation by adopting a polarization code decoding algorithm, bit error probability and frame error rate of the decoded code are calculated and a design signal to noise ratio is changed, the above operation is repeated until the bit error probability and frame error rate become the minimum. The method and system provided by the invention are suitable for general binary system memoryless channels, the bit error probability and frame error rate are low, the calculation complexity is low and the communication performance of a communication system is improved.

The invention provides a decoding method and a decoding device for polar codes concatenated with a cyclic redundancy check (CRC). The decoding method includes the following steps: SC-list decoding is carried out on the polar codes according to the number, which is L, of survival paths to obtain the L survival paths, wherein the L is a positive integer; each of the L survival paths is subjected to the CRC; and when none of the L survival paths passes the CRC, the number of the survival paths is increased, and decoding results of the polar codes are obtained according to the number, which is increased, of the survival paths. According to the decoding method and the decoding device for the polar codes concatenated with the CRC, the path number of the survival paths is adjusted according to the result of the CRC, and therefore the paths which can pass the CRC can be output as far as possible, and the decoding performance is improved.

An iterative message passing decoder, e.g., an LDPC decoder, operating in conjunction with a soft input-soft output signal processing unit, e.g., an ISI detector, has an error floor performance region influenced by the decoder's sub-optimal message passing nature. Error floor reduction is achieved by a simple message re-initialization mechanism. Decoder edge states, e.g., constraint to variable node messages in decoder memory, are reinitialized, e.g., for an iteration, during the decoding after soft values provided by signal processing unit have improved. During the message re-initialization and for some subsequent amount of iterative decoder processing, extrinsic information fed back from the decoder to the signal processing unit and / or soft values delivered to the decoder from the signal processing unit, in an outer communications loop, is temporarily frozen, e.g., using a switch and a buffer. Then, the outer communications loop is restored as the decoding continues, achieving improved decoding performance.

A digital television (DTV) transmitter and a method of coding data in the DTV transmitter are disclosed. A data formatter generates an enhanced data packet including the enhanced data and a known data sequence. A data randomizer randomizes the enhanced data packet. A RS encoder RS-codes the randomized data packet by adding first parity data, and a data interleaver interleaves the RS-coded data packet. A trellis encoding unit trellis-encodes the interleaved data packet. Herein the trellis encoding unit includes a TCM encoder for generating a first output bit by trellis-encoding a first input bit and generating a second output bit by bypassing the first input bit, and a pre-coder for generating a third output bit by pre-coding a second input bit, wherein memories included in the TCM encoder and the pre-coder are initialized when the known data sequence is inputted to the trellis encoding unit.

The present invention relates to a Vestigial Side Band (VSB) Digital Television (DTV) in agreement with the DTV standards (A / 53) of the Advanced Television System Committee (ATSC), and to a method thereof. More particularly, it provides 4-VSB DTV transceiver that improves reception performance of a receiver by transmitting and receiving dual streams formed of normal data and robust data without increasing average power, regardless of a mixing ratio of the normal and robust data. The 4-VSB DTV transceiver of the present research includes an encoding unit for encoding the robust data to be mapped to one of two groups having 4 levels {−5, −3, 1, 7} and {−7, −1, 3, 5}.

A decoding method for block-based digital encoded picture is disclosed. The method including the steps of reconstructing a zeroth reference picture list and a first reference picture list for a current picture based on a predetermined digital picture coding protocol; establishing a lookup table which includes a parameter field for storing a distance scalar, the distance scalar being derived from the time sequence characteristic values of the current picture, the co-located picture and a predetermined reference picture; determining a derived motion vector of a direct mode bi-predictive block according to the distance scalar and a predetermined motion vector of a co-located block with respect to the predetermined reference picture. An apparatus for implementing the method is also disclosed.

A method of video decoding is provided that includes receiving a data stream comprising a sequence of syntax elements that were compressed using context-adaptive binary arithmetic coding (CABAC), such that the encoding of each bin of a bin string representative of a syntax element was performed by arithmetic encoding. Two consecutive bins of a syntax element are decoded in parallel. Speculative computation and prefetching is used to reduce the critical path and thereby improve processing speed.

There is provided a wireless communication device capable of improving a decoding performance by using an optimal selection criterion for a start address and a read direction in a circular buffer. An interlacer (13) writes an interleaved and interlaced bit sequence into a circular buffer (14). An RV decision unit (109) decides the read start address and read direction of the circular buffer (14) based on the number of non-transmitted systematic bits, the number of non-transmitted important parity bits, and / or the number of non-transmitted unimportant parity bits. A read control unit (110) controls the read start address and read end address of the circular buffer (14). A read unit (15) is controlled by the read control unit (110) to continuously read encoded bits from the circular buffer (14).

An iterative message passing decoder, e.g., an LDPC decoder, operating in conjunction with a soft input-soft output signal processing unit, e.g., an ISI detector, has an error floor performance region influenced by the decoder's sub-optimal message passing nature. Error floor reduction is achieved by a simple message re-initialization mechanism. Decoder edge states, e.g., constraint to variable node messages in decoder memory, are reinitialized, e.g., for an iteration, during the decoding after soft values provided by signal processing unit have improved. During the message re-initialization and for some subsequent amount of iterative decoder processing, extrinsic information fed back from the decoder to the signal processing unit and / or soft values delivered to the decoder from the signal processing unit, in an outer communications loop, is temporarily frozen, e.g., using a switch and a buffer. Then, the outer communications loop is restored as the decoding continues, achieving improved decoding performance.

Methods and systems for transmitting and receiving data include reverse concatenated encoding and decoding. Reverse concatenated decoding includes inner decoding the encoded stream with an inner decoder that uses a low-complexity linear-block code to produce an inner-decoder output stream, outer decoding the inner-decoder output stream with an outer decoder that uses a low-density parity-check code to produce an information stream, and iterating extrinsic bit reliabilities from the outer decoding for use in subsequent inner decoding to improve decoding performance.

A decoding apparatus and method is disclosed by which the decoder error occurrence probability is suppressed and a high decoding performance can be achieved. An ABP decoding apparatus diagonalizes a parity check matrix, updates LLR values, decodes the LLR values and then adds a decoded word obtained by the decoding to a decoded word list. The ABP decoding apparatus repeats the decoding procedure as inner repetitive decoding by a predetermined number of times. Further, as the ABP decoding apparatus successively changes initial values for priority ranks of the LLR values, it repeats the inner repetitive decoding as outer repetitive decoding by a predetermined number of times. Then, the ABP decoding apparatus selects an optimum one of the decoded words from within a decoded word list obtained by the repeated inner repetitive decoding. The invention is applied to an error correction system.

An apparatus and method are provided for normalizing input soft metric to a channel decoder in a wireless communication system. A demapper generates soft metric using an in-phase component (Xk) and a quadrature component (Yk) of a received modulated symbol (Rk), a channel fading coefficient (gk) and a constant value (c) defined by a modulation order of the received modulated symbol. A normalizer receives the soft metric, computes a normalized log likelihood ratio (LLR) by multiplying the soft metric by a ratio of the constant value to a noise variance value, transforms the normalized LLR into a desired range and a desired number of bits, and outputs an input LLR of the channel decoder.

The invention discloses a method and device of generating low-density odd-even check codes for transmission in a channel. The method comprises the steps that a sending end conducts expansion on an LDPC code check basis matrix to obtain an LDPC code check matrix for coding; the sending end utilizes the LDPC code check matrix for coding to conduct LDPC coding on words to be coded to obtain encoded words; the sending end shortens the encoded words to generate the LDPC codes transmitted in the channel. By means of the technical scheme, a better decoding performance is obtained, the flexibility is higher, and the requirement of generating encoded words with different code lengths is met.