Abstract: Digital data signals such as, e.g., turbo-encoded data signals subject to decoding, are processed by producing a plurality of families of metrics for these signals while allowing one or more of these metrics to wrap through a respective independent wrapping operation. A decoder, e.g., a decoder for turbo-encoded digital signals computes differences of metrics selected out of the plurality of families of metrics by excluding differences of metrics derived through independent wrapping operations (e.g., wrapping metrics from different families) and generates signals representative of order relationships of combinations of corresponding unwrapped metrics as a function of said differences.

Abstract: Digital data signals such as, e.g., turbo-encoded data signals subject to decoding, are processed by producing a plurality of families of metrics for these signals while allowing one or more of these metrics to wrap through a respective independent wrapping operation. A decoder, e.g., a decoder for turbo-encoded digital signals computes differences of metrics selected out of the plurality of families of metrics by excluding differences of metrics derived through independent wrapping operations (e.g., wrapping metrics from different families) and generates signals representative of order relationships of combinations of corresponding unwrapped metrics as a function of said differences.

Abstract: The method transmits a long packet of digital data over a poly-phase power line affected by impulsive noise synchronous with phase voltages. Instead of using very complicated coding schemes, starting from the knowledge of the typical power line scenario, useful information is transmitted where noise synchronous with the main signal is absent. Time-intervals of a known or estimated duration during which the poly-phase power line is affected by impulsive noise are determined, and dummy data during the time-intervals, and useful data during other time-intervals free from impulsive noise, are transmitted.

Abstract: A method of estimating a signal-to-noise ratio from a received M-DPSK modulated signal, comprising a sequence of N known symbols, based on a division of the known symbols N and of N samples of the received signal at the output of the channel into a number of blocks B of length L with B greater than one.

Abstract: A method for loading bits over a set of subcarriers of a multiple-carrier communications system comprises the operation of associating with the subcarriers respective numbers of bits chosen from among a plurality of available constellations. The method envisages definition of a performance target for the system and execution of bit loading, guaranteeing the aforesaid target on a plurality of subcarriers. The performance target can be a target error rate, such as a bit-error rate (BER), or else be transferred into a constraint, such as, for example, a threshold, in a metric of log-likelihood ratios (LLRs). In this case, there is preferably envisaged application to the signals received within the multiple-carrier system a function that estimates a signal to noise ratio on each sub-carrier. The aforesaid metric of log-likelihood ratios (LLRs) is hence defined as a function of said signal to noise ratios.

Abstract: Log-likelihood ratios are approximated for encoded bits modulated with a 2m-ary QAM constellation. Each symbol of the constellation is identified by a respective string of m bits. The log-likelihood ratio of each bit of the m bits is approximated with a product ? of a respective factor by a respective variable D that depends on a received signal and on communication channel characteristics. The approximating includes determining a value of at least one of the variables D using a parametric nonlinear function of an equalized replica z of a respective received signal.

Abstract: The method transmits a long packet of digital data over a poly-phase power line affected by impulsive noise synchronous with phase voltages. Instead of using very complicated coding schemes, starting from the knowledge of the typical power line scenario, useful information is transmitted where noise synchronous with the main signal is absent. Time-intervals of a known or estimated duration during which the poly-phase power line is affected by impulsive noise are determined, and dummy data during the time-intervals, and useful data during other time-intervals free from impulsive noise, are transmitted.

Abstract: A method of estimating a signal-to-noise ratio from a received M-DPSK modulated signal, comprising a sequence of N known symbols, based on a division of the known symbols N and of N samples of the received signal at the output of the channel into a number of blocks B of length L with B greater than one.

Abstract: A QAM receiver for constellations having at least 16 symbols converts its received QAM signal into outputs including indications of the received symbols. A channel frequency response estimator responsive to outputs of the converter derives indications of estimates of effects of a link to the receiver on the phase and amplitude of the received signals. A processor responsive to outputs of the converter and the estimator (1) equalises the phases of the converter outputs, (2) scales the amplitude estimates by amounts determined by the amplitude associated with the separation of boundaries between symbols in the constellation, and (3) combines the phase equalised converter outputs and the scaled amplitude estimates to derive likely bit values of the received symbols.

Abstract: A method for loading bits over a set of subcarriers of a multiple-carrier communications system comprises the operation of associating with the subcarriers respective numbers of bits chosen from among a plurality of available constellations. The method envisages definition of a performance target for the system and execution of bit loading, guaranteeing the aforesaid target on a plurality of subcarriers. The performance target can be a target error rate, such as a bit-error rate (BER), or else be transferred into a constraint, such as, for example, a threshold, in a metric of log-likelihood ratios (LLRs). In this case, there is preferably envisaged application to the signals received within the multiple-carrier system a function that estimates a signal to noise ratio on each sub-carrier. The aforesaid metric of log-likelihood ratios (LLRs) is hence defined as a function of said signal to noise ratios.

Abstract: Log-likelihood ratios are approximated for encoded bits modulated with a 2m-ary QAM constellation. Each symbol of the constellation is identified by a respective string of m bits. The log-likelihood ratio of each bit of the m bits is approximated with a product ? of a respective factor by a respective variable D that depends on a received signal and on communication channel characteristics. The approximating includes determining a value of at least one of the variables D using a parametric nonlinear function of an equalized replica ? of a respective received signal.

Abstract: A QAM receiver for constellations having at least 16 symbols converts its received QAM signal into outputs including indications of the received symbols. A channel frequency response estimator responsive to outputs of the converter derives indications of estimates of effects of a link to the receiver on the phase and amplitude of the received signals. A processor responsive to outputs of the converter and the estimator (1) equalises the phases of the converter outputs, (2) scales the amplitude estimates by amounts determined by the amplitude associated with the separation of boundaries between symbols in the constellation, and (3) combines the phase equalised converter outputs and the scaled amplitude estimates to derive likely bit values of the received symbols.