Blind Recognition of Self-synchronous Scramblers Based on Cosine Conformity

In order to overcome the shortcomings of the existing non-cooperative self-synchronous scramblers recognition algorithms with low recognition rate and poor adaptability under low signal-to-noise ratio, a blind recognition method of self-synchronous scramblers based on cosine conformity is proposed. Firstly, based on the source imbalance and self-synchronous scramblers descrambling principle, the error-containing check equation of the self-synchronous scramblers is established, and then the received soft decision sequence is converted into the posterior probability sequence of the information symbol. The possible generating polynomials are traversed. The cosine conformity is introduced as a statistic in the traversal process, and the optimal discrimination threshold is solved by analyzing the statistical characteristics of the cosine conformity. The self-synchronous scramblers generating polynomial is identified according to the relationship between the statistics and the discrimination threshold. The simulation results show that the algorithm can effectively identify the generating polynomial, and the recognition rate is better than the existing algorithm under low signal-to-noise ratio, and it has good low signal-to-noise ratio adaptability. When the source imbalance is 0.1, the length of the intercepted scrambling code sequence is 800 bit and 0.05, and the length of the intercepted scrambling code sequence is 3000 bit, the identification of the generating polynomial can be effectively completed. Compared with the current algorithm, the recognition performance of this algorithm is better than the existing hard decision. The performance of the algorithm is improved by 1 similar to 2 dB compared with the hard decision algorithm.