This invention discloses a kind of reliable data transmission method based on hidden Markov model that specific to video transmission quality enhancement over lossy satellite links. It uses HMM model to forecast retransmission rate and adopts the network packet loss rate to reflect the network performance. The underlying network packet loss rate is used as the hidden state of HMM model and the retransmission rate is used as the observation state. By analyzing the historically transmitted data sessions, APRT establishes the relationship between the hidden state transition probability and the emission probability. Then, a robust and efficient retransmission rate prediction is obtained. This invention takes into full consideration of high BER in satellite network channels and adjusts the reliable level according to the satellite network channel characteristics so as to make tradeoff between instantaneity and quality. Consequently, it guarantee the QoS and QoE of video stream.

In some embodiments, a bandwidth constrained equalized transport (BCET) communication system comprises a transmitter that transmits a signal, a communication channel that transports the signal, and a receiver that receives the signal. The transmitter can comprise a pulse-shaping filter that intentionally introduces memory into the signal, and an error control code encoder that is a low-density parity-check (LDPC) error control code encoder. The error control encoder comprises code that is optimized based on the intentionally introduced memory into the signal, a code rate, a signal-to-noise ratio, and an equalizer structure in the receiver. In some embodiments, the communication system is bandwidth constrained, and the transmitted signal comprises an information rate that is higher than for an equivalent system without intentional introduction of the memory at the transmitter.

A method, an apparatus and a communication system of evaluating a nonlinear compensation performance. The method for evaluating a nonlinear compensation performance comprises: evaluating a nonlinear compensation performance by using a probability-maintained notch signal as a test signal; the probability-maintained notch signal having a probability density function (PDF) that is maintained unchanged after notching as compared with before notching.

An iterative receiver receives a signal including useful and interfering signal components, and detects information carried thereon. The receiver includes at least one estimating unit receiving the signal and providing an estimate of each signal component, and at least two decoding and regenerating units, at each iteration, each decoding and regenerating unit decoding a respective one among the estimates and for regenerating the respective decoded estimate into a respective regenerated estimate. At each receiver iteration, the at least one estimating unit provides estimates based on regenerated estimates provided at a previous iteration. The receiver further includes a control unit determines activation or deactivation of each decoding and regenerating unit at each process step of a detection process dedicated to detection of the signal, and determines, for each process step, a respective number of allowed iterations for each decoding and regenerating unit whose activation has been determined for that process step.

A likelihood generation device is included in a receiving apparatus that receives a code-modulated signal including nk information bits and k parity bits in N-dimensional arrangement, where N is a natural number greater than or equal to four, and n and k are natural numbers with k<n. The likelihood generation device includes: a temporary likelihood determination unit to determine, by using a table that includes an L-dimensional address space and stores a likelihood in each of the L-dimensional address spaces, likelihoods of an information bit and a parity bit that are transmitted by the code-modulated signal received, where L is a natural number with L<N; and a likelihood correction unit to update, among the likelihoods determined by the likelihood derivation unit, the likelihood of the information bit on a basis of a rule for generation of the parity bit.

A method includes: generating a trellis; generating one or more predicted symbols using a first non-linear model; computing and saving two or more branch metrics using a priori log-likelihood ratio (LLR) information, a channel observation, and the one or more predicted symbols; if alpha forward recursion has not yet completed, generating alpha forward recursion state metrics using a second non-linear model; if beta backward recursion has not yet completed, generating beta backward recursion state metrics using a third non-linear model; if sigma forward recursion has not yet completed, generating sigma forward recursion state metrics using the branch metrics, the alpha state metrics, and the beta backward recursion state metrics; generating extrinsic information comprising a difference of a posteriori LLR information and the a priori LLR information; computing and feeding back the a priori LLR information; and calculating the a posteriori LLR information.

Disclosed is a precoding method for generating, from a plurality of baseband signals, a plurality of precoded signals that are transmitted in the same frequency bandwidth at the same time. According to the precoding method, one matrix is selected from among matrices defining a precoding process that is performed on the plurality of baseband signals by hopping between the matrices. A first baseband signal and a second baseband signal relating to a first coded block and a second coded block generated by using a predetermined error correction block coding scheme satisfy a given condition.

A method selects frequency channels in a communication system using a frequency hopping method, in which data are transmitted between a transmitter and a receiver. The data are transmitted as data packets having a plurality of bits in a frequency/time block. A respective data packet is coded before transmission by the transmitter and is decoded after reception by the receiver. The transmission quality of the frequency channels is evaluated and, a decision is made for a selection of the frequency channel which is used for the transmission of the data. A likelihood ratio for the likelihood of a successful transmission is determined before the decoding by the receiver, the likelihood ratio is used as a metric for determining the interference state of the respective data packet, and the transmission quality of the respective frequency channel is evaluated on the basis of the interference state of the data packet.

In some embodiments, a bandwidth constrained equalized transport (BCET) communication system comprises a transmitter that transmits a signal, a communication channel that transports the signal, and a receiver that receives the signal. The transmitter can comprise a pulse-shaping filter that intentionally introduces memory into the signal, and an error control code encoder that is a low-density parity-check (LDPC) error control code encoder. The error control encoder comprises code that is optimized based on the intentionally introduced memory into the signal, a code rate, a signal-to-noise ratio, and an equalizer structure in the receiver. In some embodiments, the communication system is bandwidth constrained, and the transmitted signal comprises an information rate that is higher than for an equivalent system without intentional introduction of the memory at the transmitter.

The present invention is directed to data communication. More specifically, an embodiment of the present invention provides an error correction system. Input data signals are processed by a feedforward equalization module and a decision feedback back equalization module. Decisions generated by the decision feedback equalization module are processed by an error detection module, which determines error events associated with the decisions. The error detection module implements a reduced state trellis path. There are other embodiments as well.