Abstract: A decoder (30) for decoding low-density parity-check (LDPC) codewords. The decoder includes at least one core (10) and a memory (20) in which a number NC of predefined configurations are stored. The core is suitable for being dynamically configured with any one of the predefined configurations stored in the memory to decode an LDPC codeword using this configuration. The predefined configurations form a sub-group, in the strict sense, of 5G LDPC configurations defined in the 3GPP TS 38.212 standard. Each configuration corresponds to a triplet of three parameters {K, R, Z}, and to a parity matrix constructed according to at least a portion of these parameters. K is a message size encoded by the LDPC code, Z is an expansion factor of the parity matrix, and R is a code rate of the LDPC code.

Abstract: A multi-core decoder (31) for decoding low-density parity-check (LDPC) codewords. The multi-core decoder includes a group of cores (10) capable of each simultaneously decoding a different LDPC codeword. The group includes memory (20) shared between the cores (10) in which predefined Nc configurations are stored. Each predefined configuration includes a binary parity matrix corresponding to an LDPC code. Each core is suitable for being dynamically configured with any one of the Nc predefined configurations stored in the shared memory (20) to decode an LDPC codeword using a selected Nc configuration.

Abstract: The disclosure relates to an LDPC decoding method which involves performing iterations until a stop criterion is satisfied. Each iteration involves calculating variable messages (?n,m), calculating parity check messages (?m,n), and calculating a posteriori estimation variables. The parity check messages (?m,n) and the posteriori estimation variables (?n) being saturated at a predetermined maximum value. At the end of an iteration, when the number of saturations reaches a specified threshold, the method involves at least a first scaling of the parity check messages (?m,n) and the a posteriori estimation variables (?n). Scaling corresponds to assigning, to a value, an integer which has the same sign and whose absolute value is the nearest integer greater than the absolute value of the value divided by two.

Abstract: An LDPC decoding method is disclosed in which the LDPC code is defined by a parity matrix having a layered structure, and the method involves performing iterations until a stop criterion is satisfied. Each iteration involves the successive processing of the different layers. Processing a layer involves calculating variable messages (an,m), calculating parity check messages, calculating a posteriori estimation variables (?n), and calculating a partial syndrome. The evaluation of the stop criterion involves checking if, for a plurality of successive iterations, the number of iterations for which all the partial syndromes are zero, from which the number of iterations for which at least one of the partial syndromes is non-zero is subtracted, is greater than or equal to a predetermined stop threshold.

Abstract: The disclosure relates to an LDPC decoding method which involves performing iterations until a stop criterion is satisfied. Each iteration involves computing variable messages (?n,m), computing parity check messages (?m,n), and computing a posteriori estimation variables. Computing a parity check message (?m,n) for a parity check node (CNm) involves determining the two smallest values (Mini1, Min2) among the absolute values of the variable messages associated with the parity check node (CNm), comparing a difference between said values with a threshold, determining a correction value according to the result of the comparison, and computing the parity check message according to the correction value.

Abstract: The disclosure relates to an LDPC decoding method which involves performing iterations until a stop criterion is satisfied. Each iteration involves computing variable messages (?n,m), computing parity check messages (?m,n), and computing a posteriori estimation variables. Computing a parity check message (?m,n) for a parity check node (CNm) involves determining the two smallest values (Min1, Min2) among the absolute values of the variable messages associated with the parity check node (CNm), comparing a difference between said values with a threshold, determining a correction value according to the result of the comparison, and computing the parity check message according to the correction value.

Abstract: An LDPC decoding method is disclosed in which the LDPC code is defined by a parity matrix having a layered structure, and the method involves performing iterations until a stop criterion is satisfied. Each iteration involves the successive processing of the different layers. Processing a layer involves calculating variable messages (?n,m), calculating parity check messages, calculating a posteriori estimation variables (?n), and calculating a partial syndrome. The evaluation of the stop criterion involves checking if, for a plurality of successive iterations, the number of iterations for which all the partial syndromes are zero, from which the number of iterations for which at least one of the partial syndromes is non-zero is subtracted, is greater than or equal to a predetermined stop threshold.

Abstract: The disclosure relates to an LDPC decoding method which involves performing iterations until a stop criterion is satisfied. Each iteration involves calculating variable messages (?n,m), calculating parity check messages (?m,n), and calculating a posteriori estimation variables. The parity check messages (?m,n) and the posteriori estimation variables (?n) being saturated at a predetermined maximum value. At the end of an iteration, when the number of saturations reaches a specified threshold, the method involves at least a first scaling of the parity check messages (?m,n) and the a posteriori estimation variables (?n). Scaling corresponds to assigning, to a value, an integer which has the same sign and whose absolute value is the nearest integer greater than the absolute value of the value divided by two.

Abstract: A device (10) for interleaving data blocks for an optical communications system between a satellite and an earth station. The interleaving device (10) includes a control module (11), a cache memory (15) and an external memory (12). The cache memory (15) includes buffer areas (16). The control module (11) is configured to write each new frame of blocks (21) received in an available buffer area (16), to form (102) groups (22) of interleaved blocks from different blocks (21) belonging to different frames (20) stored in different buffer areas (16), and to write (103) each group (22) of interleaved blocks thus formed in a sequential area (13b) of the external memory (12).

Abstract: A data encoding device suitable for encoding a plurality of LDPC codes is disclosed including an input interface and an output interface, and a first circuit for encoding quasi-cyclic LDPC code, connected at an input to the input interface and at an output to the input of a first multiplexer circuit, a second circuit for encoding quasi-cyclic LDPC code, connected at an input to the input interface and at an output to the input of the first multiplexer circuit, a third circuit for encoding quasi-cyclic LDPC code, connected at an input to the output of the first multiplexer circuit and at an output to the input of a second multiplexer circuit.

Abstract: A method and a receiver device for detecting the start of a frame of a satellite communication signal. A shaping filtering is applied directly after sampling of the signal, before a frequency correction is applied. During a first phase, an approximate frequency error and a candidate first sample for the start of the frame are estimated by performing several correlations respectively associated with different frequency hypotheses. The samples obtained after sampling or after shaping filtering are buffered during the execution of the first phase. Then, during a second phase, a final candidate sample for the start of the frame is determined from the memorised samples, using the approximate frequency error and the candidate first sample estimated during the first phase.

Abstract: A data encoding device suitable for encoding a plurality of LDPC codes is disclosed including an input interface and an output interface, and a first circuit for encoding quasi-cyclic LDPC code, connected at an input to the input interface and at an output to the input of a first multiplexer circuit, a second circuit for encoding quasi-cyclic LDPC code, connected at an input to the input interface and at an output to the input of the first multiplexer circuit, a third circuit for encoding quasi-cyclic LDPC code, connected at an input to the output of the first multiplexer circuit and at an output to the input of a second multiplexer circuit.

Abstract: A method and a receiver device for detecting the start of a frame of a satellite communication signal. A shaping filtering is applied directly after sampling of the signal, before a frequency correction is applied. During a first phase, an approximate frequency error and a candidate first sample for the start of the frame are estimated by performing several correlations respectively associated with different frequency hypotheses. The samples obtained after sampling or after shaping filtering are buffered during the execution of the first phase. Then, during a second phase, a final candidate sample for the start of the frame is determined from the memorised samples, using the approximate frequency error and the candidate first sample estimated during the first phase.

Abstract: A method for receiving an ADS-B message is disclosed including a synchronisation phase for detecting the start of the message and a decoding phase for recovering a bit stream corresponding to a block of data in the message. The synchronisation phase is based on determining a sequence of log-likelihood ratios having the greatest likelihood of corresponding to a sequence of symbols expected from a preamble of the message. Each log-likelihood ratio corresponds to a ratio between the respective probabilities that a symbol of the signal received corresponds to one of two possible values for a symbol. The decoding phase applies a belief propagation algorithm to a sequence of log-likelihood ratios respectively associated with the symbols in the block of data in the message, with an optimised parity matrix of the cyclic redundancy code of the message.

Abstract: A method for receiving an ADS-B message is disclosed including a synchronisation phase for detecting the start of the message and a decoding phase for recovering a bit stream corresponding to a block of data in the message. The synchronisation phase is based on determining a sequence of log-likelihood ratios having the greatest likelihood of corresponding to a sequence of symbols expected from a preamble of the message. Each log-likelihood ratio corresponds to a ratio between the respective probabilities that a symbol of the signal received corresponds to one of two possible values for a symbol. The decoding phase applies a belief propagation algorithm to a sequence of log-likelihood ratios respectively associated with the symbols in the block of data in the message, with an optimised parity matrix of the cyclic redundancy code of the message.

Abstract: A method for transmitting, by a terminal, a message destined for a receiver station of a wireless communication system. The message being transmitted on a shared channel on which the transmission of messages is performed at the start of predetermined time intervals, termed slots. Data to be included in the message to be transmitted is encoded. The encoded data is distributed between Nb sub-messages of the message to be transmitted, Nb being an integer number greater than or equal to two. A slot is selected for transmitting the message. Nb transmission frequencies are selected, each respectively associated with the Nb sub-messages of the message. The message is transmitted at the start of the selected slot, by successively transmitting the sub-messages on their respective associated transmission frequencies.

Abstract: A method (50) for estimating a frequency shift and a frequency drift affecting a useful signal including a code word formed by a channel encoder, including an analysis phase (51) including: for two analysis frequency drifts: a compensation (52) of the analysis frequency drift on the useful signal, an estimation (53) of the frequency shift on each useful signal obtained after compensation, a selection (54) of frequency hypotheses, and an estimation phase (55) including: for each frequency hypothesis: a frequency recalibration (56) of the useful signal depending on the frequency hypothesis, in order to obtain sample sequences, an evaluation (57) of the probability of each sample sequence to be a code word of said channel encoder, an estimation (58) of the frequency shift and of the frequency drift depending on the most probable frequency hypothesis.

Abstract: A method (50) for estimating a frequency shift and a frequency drift affecting a useful signal including a code word formed by a channel encoder, including an analysis phase (51) including: for two analysis frequency drifts: a compensation (52) of the analysis frequency drift on the useful signal, an estimation (53) of the frequency shift on each useful signal obtained after compensation, a selection (54) of frequency hypotheses, and an estimation phase (55) including: for each frequency hypothesis: a frequency recalibration (56) of the useful signal depending on the frequency hypothesis, in order to obtain sample sequences, an evaluation (57) of the probability of each sample sequence to be a code word of said channel encoder, an estimation (58) of the frequency shift and of the frequency drift depending on the most probable frequency hypothesis.

Abstract: A method for detecting useful signals in an overall signal. Each useful signal may be affected with a frequency drift. In the detection phase, frequency spectra for detecting the overall signal for multiple detection time windows are calculated and useful signals according to the detection frequency spectra are detected. In the estimation phase, for each useful signal detected: the frequency of the overall signal for multiple frequency drift values is reset. In the estimation phase, for each useful signal detected, a frequency spectrum is calculated for the estimation of the overall signal for each frequency drift value over an estimation time window having the useful signal detected and of a duration higher than the detection time window. In the estimation phase, for each useful signal detected, the frequency drift is estimated affecting the useful signal detected according to the estimation frequency spectra.

Abstract: A method for detecting useful signals in an overall signal. Each useful signal may be affected with a frequency drift. In the detection phase, frequency spectra for detecting the overall signal for multiple detection time windows are calculated and useful signals according to the detection frequency spectra are detected. In the estimation phase, for each useful signal detected: the frequency of the overall signal for multiple frequency drift values is reset. In the estimation phase, for each useful signal detected, a frequency spectrum is calculated for the estimation of the overall signal for each frequency drift value over an estimation time window having the useful signal detected and of a duration higher than the detection time window. In the estimation phase, for each useful signal detected, the frequency drift is estimated affecting the useful signal detected according to the estimation frequency spectra.