75 results about "Raptor code" patented technology

A system and method for encoding symbols in a wireless communication is provided. The system and method includes a transmitter configured to encode data transmissions. The transmitter includes a raptor encoder configured to perform a coding operation. The raptor encoder generates intermediate symbols without using a half-code such that the intermediate symbols consist of precoded symbols and parity symbols. Thereafter, the intermediate symbols are encoded using a Luby Transform to produce and output encoded symbols. The transmitter further is configured to transmit one or more of the source symbols, parity symbols or encoded symbols.

The invention discloses a Raptor Codes encoding / decoding method suitable for medium / short code lengths of an additive white Gaussian noise channel. According to the method disclosed by the invention, the degree distribution of the inner codes, i.e. LT (Linear-Time) Codes, of the Raptor Codes which are more suitable for the medium / short code lengths is proposed; and the improved PEG (Progressive Edge-Growth) algorithm is used for encoding the inner codes, i.e. the LT codes, of the Raptor Codes, wherein the encoding manner consists of two PEG encoding manners, i.e. independently carrying out PEG composition on the LT Codes and carrying out the PEG composition on the LT Codes through combining with outer codes, i.e. LDPC (Low Density Parity Check) Codes, thus the problem that excessive shortloops appear in a Tanner graph, caused by randomly selecting information packets in an LT encoding stage, is solved. With the adoption of the method disclosed by the invention, the effectiveness for the transfer of soft information when the BP (Background Processing) iterative decoding is carried out is therefore enhanced, the performance better than that of a random composition manner is obtained, and the more reliable transmission for the rateless codes with the medium / short code lengths is realized.

Significant improvement in Raptor codes and punctured LDPC codes are obtainable by use of the invention. In both a transmission scheme for Raptor-encoded or LDPC-encoded information, a dynamic adjustment approach is employed. A fraction of a codeword or information frame is transmitted. A feedback signal is sent from the receiver to the transmitter indicating either 1) successful decoding, or 2) failure to decode and / or a feedback signal indicative of a statistical measure of transmission channel quality. If decoding fails, a further portion of the codeword or frame is sent. The intensity and / or size of the fraction is adjusted based on the feedback signal. In one embodiment, a specific range for probabilities employed in the encoding process for Raptor codes provides the ability to increase transmission throughput. Further it has been found that the advantageous Raptor codes are useful in noise conditions where even the improved punctured LDPC codes of the invention begin to degrade.

The invention discloses an aviation ad hoc network transmission method based on reliable UDP and fountain codes. The method uses Raptor coding to avoid retransmission of a large number of data packetsin a high packet loss environment. A lightweight feedback mechanism is designed to provide reliability. The method comprises using an improved SNACK mechanism for handling an asymmetric bandwidth; using a novel sliding window mechanism for accurately computing the RTT to solve the problem of ambiguity in TCP retransmission; and providing a congestion control method for distinguishing between congestion packet loss and link switch packet loss in the aviation ad hoc network. The method of the invention satisfies the efficient and reliable transmission requirements of the aviation ad hoc network.

A system and method for encoding symbols in a wireless communication is provided. The system and method includes a transmitter configured to encode data transmissions. The transmitter includes a raptor encoder configured to perform a coding operation. The raptor encoder generates intermediate symbols without using a half-code such that the intermediate symbols consist of precoded symbols and parity symbols. Thereafter, the intermediate symbols are encoded using a Luby Transform to produce and output encoded symbols. The transmitter further is configured to transmit one or more of the source symbols, parity symbols or encoded symbols.

The invention provides a multimedia data unequal error protection method based on a Raptor code. The method includes two application modes of basic unequal error protection and reinforced unequal error protection, and unequal error protection of multimedia data packages is achieved through the steps of distortion impact evaluation, sequencing and classification, Raptor coding and transmitting and the like. The method completely utilizes the good characteristics of the Raptor code under large block length. In addition, the method is easy to use due to the fact that the standard Raptor code is used.

A video encoder system includes a base layer and an enhancement layer for encoding video data. The base layer encodes a reduced quality version of the video data to obtain base layer data. The enhancement layer encodes the video data using energy-concentrating transform operations, nested scalar quantization, and Raptor encoders. The base layer data and enhancement layer data are transmitted through a channel to a video decoder system. The decoder system decodes the base layer data to recover an estimate of the reduced quality video and decodes the enhancement layer data (using the reduced quality video as side information) to obtain blocks of coset indices. The decoder system then operates on the blocks of coset indices to generate estimates of the original video data.

A system and method for recovering erased symbols in a wireless communication is provided. The system and method includes a receiver configured to receive encoded data transmissions. The receiver includes a single stage decoder configured to perform a decoding operation. The single stage decoder also is configured to determine a symbol erasure rate, the symbol erasure rate defined by a number of erased symbols. The single stage decoder further is configured to generate a recovery matrix based on the symbol erasure rate and invert the recovery matrix. Thereafter, the single stage decoder recovers the erased symbols based on a function of the inverted recovery matrix.

The invention discloses a high-scale Raptor code encoding and decoding method with a limited code length. The method comprises the steps of performing pre-encoding on data whose original symbol number is k to obtain an intermediate symbol whose length is n, and then performing LT encoding on the intermediate symbol to obtain a Raptor code whose encoding redundancy is gamma; elements and an original symbol b in a pre-encoding generated matrix, as shown in the specification, of the whole Raptor code and an LT code generated matrix as shown in the specification all are high-scale elements in a q-element domain, a high-scale LDGM code is adopted by the pre-encoding and the generated matrixes are in a full rank; matrix construction is performed on the LT encoding generated matrix according to a degree distribution omega, and a degree value d of each row is subject to a probability distribution as shown in the specification and as shown in the specification; non-zero elements in the generated matrixes are generated randomly; and all non-zero elements in the pre-encoding and the LT encoding are generated according to a Bernoulli variable eta and an output degree distribution omega (x) in an equal probability 1 / q. According to the high-scale Raptor code encoding and decoding method, an upper limit and a lower limit of a decoding failure probability of any scale Raptor code under an ML (Maximum Likelihood) decoding algorithm are given, the performance of an actual codeword is simulated by Monte Carlo, and the accuracy of the upper and lower limits are verified.