The existing methods for interleaver estimation usually use hard-decision of the demodulator output sequence

their robustness against error bits is to be improved and some methods only aim at certain interleavers.Focusing on the random interleaver of Turbo codes

this paper presents an estimation algorithm which uses soft-decision.Firstly

the concept and calculation method of the average conformity of parity-check equation are given.Then

the permutation positions of the interleaver are estimated step by step

using the truth that the correct permutation position could maximize the average conformity of parity-check equation.Especially

the proposed algorithm still performs well in puncturing case.Results of simulation experiments show that our algorithm has better performance and relatively lower complexity

especially in low signal-to-noise ratio cases

compared to the existing relevant algorithms.