Blind Recognition of Polar Code Information Bits Based on Multi-Threshold Voting and Partial Orders

Blind recognition of polar codes in non-cooperative scenarios remains insufficiently addressed. Although existing methods have achieved reliable performance in code length recognition, reliably identifying information bits remains challenging under moderate-to-high bit error rate (BER). In this letter, assuming the code length is known, we propose a two-stage blind information bits recognition scheme. In the first stage, multi-threshold voting judgment is performed to obtain the initial frozen set. In the second stage, we perform partial orders (POs) correction to enforce structural consistency of the frozen set. When BER ranges from 0 to 0.2, simulations show that the proposed method, at the cost of modest computational complexity, significantly improves the information bits identification accuracy compared with existing estimation and derivation-based approaches, achieving relative gains of approximately 40.0%, 20.7% and 13.8% for polar codes (32,15), (64,30), and (128,64), respectively.