Parameter Estimation of Turbo Code Encoder

Abstract

The problem of reconstruction of a channel code consists of finding out its design parameters solely based on its output. This paper investigates the problem of reconstruction of parallel turbo codes. Reconstruction of a turbo code has been addressed in the literature assuming that some of the parameters of the turbo encoder, such as the number of input and output bits of the constituent encoders and puncturing pattern, are known. However in practical noncooperative situations, these parameters are unknown and should be estimated before applying reconstruction process. Considering such practical situations, this paper proposes a novel method to estimate the above-mentioned code parameters. The proposed algorithm increases the efficiency of the reconstruction process significantly by judiciously reducing the size of search space based on an analysis of the observed channel code output. Moreover, simulation results show that the proposed algorithm is highly robust against channel errors when it is fed with noisy observations.

Blind parameter estimation of turbo convolutional codes: Noisy and non-synchronized scenario

“…The existing method in [17] achieves 95% (EM) method [17], which identifies only first RSC encoder parameters. In addition, the proposed algorithms achieve almost equivalent performance as that of existing method in [20]. As mentioned before, the algorithm proposed in [20] estimates only total codeword length and code dimension of TCCs assuming two identical RSC encoders without estimating the parameters of constituent RSC encoders and interleavers.…”

“…In addition, the proposed algorithms achieve almost equivalent performance as that of existing method in [20]. As mentioned before, the algorithm proposed in [20] estimates only total codeword length and code dimension of TCCs assuming two identical RSC encoders without estimating the parameters of constituent RSC encoders and interleavers. We estimate the total codeword length and code dimension of TCCs over non-erroneous and erroneous channel conditions using Algorithms 1 and 2, respectively.…”

“…An efficient algorithm for recovering the permutation of the interleaver in turbo encoder was proposed in [19]. The problem of reconstruction of the turbo encoder system has also been addressed in [20] and a method to estimate turbo convolutional code (TCC) parameters was given. However, the proposed method estimates only total codeword length and code dimension of TCCs assuming two identical RSC encoders without estimating the parameters of individual constituent RSC encoders and interleavers.…”

“…• The proposed algorithm in [20] recognized the total codeword length and code dimension of TCCs without estimating the parameters of individual constituent RSC encoders and interleavers.…”

“…• In addition, the proposed algorithms or methods in [17]- [20] were limited only to synchronized environment.…”