A Robust Method for Estimating Periods of Block Interleavers

For estimating the period of a block interleaver, the robustness of Gaussian elimination-based method is not high. To overcome this limitation, a modified estimation method is proposed. The interleaved sequence is reshaped into a matrix firstly. Then Gaussian elimination is used to estimate the rank of the matrix, and if the number of matrix columns is a multiple of the period of the block interleaver, the matrix is of deficient rank. In the procedure of Gaussian elimination, the threshold of judging dependence of the columns is revised and soft-decision data is used to select reliable bits to decrease bit errors in the matrix. Compared with original method, the robustness of our method improves.