Abstract:
According to the invention, for the transmission of sequences of information items referred to as "code words", among which sequences referred to as "operative words" are selected, on reception of a signal representing received words, each formed from a sequence of numbers having one of at least three values, and representing a code word, the following are implemented: a function of combining two sequences, one of which is an operative word, the said combination providing a so-called "resultant" sequence; a measurement whereby there is made to correspond to each sequence a real number representing the degree of coherence of the sequence; and, for each word received; at least one sequence resulting from the said received word and from an operative word is calculated iteratively and the said received word is replaced by the said resultant sequence from the moment when the measurement of the degree of coherence of the latter indicates a coherence less than that of the received word, this resultant sequence being referred to as a "replacement sequence", until no new combination of the last replacement sequence with any operative word exhibits a degree of coherence whose measurement is less than that of the said last replacement sequence,; the said last replacement sequence then being considered as representing the difference between the word received and the code word which it represents.
Abstract:
The present invention concerns a method of coding information symbols according to a code defined on a Galois field Fq, where q is an integer greater than 2 and equal to a power of a prime number, and of length n=p(q−1), where p>1. This coding is designed so that there exists a corresponding decoding method, also disclosed by the invention, in which the correction of transmission errors essentially comes down to the correction of errors in p words of length (q−1) coded according to Reed-Solomon. The invention is particularly advantageous when, through a suitable choice of parameters, the code according to the invention is an algebraic geometric code: in this case, it is possible to correct the transmission errors by the method already mentioned and/or by a conventional method which is less economical but has a higher performance.
Abstract:
The present invention concerns channel codes particularly well adapted to transmission in channels in which errors tend to occur in bursts. Moreover, the codes according to one embodiment of the invention using an algebraic geometric curve are easy to decode and have a relatively high minimum distance. The invention also relates to the corresponding encoding and decoding methods, as well as the devices and apparatuses adapted to implement those methods. Application is in particular to mass storage, and to systems of communication by OFDM.