Patent ID: 7900121

Claim:
A method for determining indices assigned to error correction symbols, wherein encoded code symbols are generated using a generator matrix of a block code from a number of source symbols and the encoded code symbols are transmitted from a transmitting device to a receiving device, with transmission errors occurring in the received code symbols, wherein the indices of the error correction symbols that are to be transmitted are determined according to the following steps: a) determining the largest index of all the received code symbols; b) specifying a first parameter which has a value that is greater than the largest index of all the received code symbols; c) forming a first matrix row by row from a coding matrix derived from the generator matrix such that the i-th row of the coding matrix is copied into the first matrix for an i-th coding symbol received without error(s); d) marking each column of the first matrix via a column index corresponding to a column number of the coding matrix; e) transforming the first matrix via at least a elementary row transformations or column transposition into a second matrix having RG independent rows, where RG corresponds to a rank of the second matrix; f) setting a second parameter equal to the first parameter+m−1, wherein m is a third integer parameter determined according to the form: m≦L−RG ( M 2), wherein L is the number of intermediate symbols, wherein RG is the rank, and M 2 the second matrix; g) setting a fourth parameter equal to the first parameter; h) forming a third matrix row by row from the second matrix and from the coding matrix such that all rows between the R-th inclusive and the Rmax-th inclusive of the coding matrix are copied into the third matrix, the copying including the performing of the column transpositions for the rows to be copied that were carried out in order to form the second matrix; i) transforming the third matrix via at least an elementary row transformations or column transposition into a fourth matrix having RH independent rows, where RH corresponds to a rank of the fourth matrix; j) when the fourth matrix has no full rank: setting the fourth parameter to the second parameter, determining a fifth parameter is determined which is determined from the difference between the number of intermediate symbols and the rank of the fourth matrix according to the formula n≦L−RG ( M 4), wherein the second parameter is incremented by n, and—steps h) to i) are repeated, with the fourth matrix being used instead of the second matrix; and k) when the fourth matrix has a full rank: identifying a range of encoded code symbols via the first and the second parameter, whereby said range can be requested in the form of at least one error correction symbol by the receiving device from the transmitting device for the purpose of error-free reconstruction of the source symbols.