Interleaver Design for LDPC-Partial Polar Codes Based on EXIT Analysis

The concatenation of polar codes with LDPC codes is a promising approach to enhance the performance of polar codes at finite lengths while suppressing the error floor of LDPC codes. The polarized bit-channels of polar coding at finite lengths exhibit different qualities, i.e., some are almost noiseless while others are noisy. This implies that unbalanced protection is needed in the design of concatenating polar codes with other codes. To this end, a scheme of concatenatng polar codes with outer irregular LDPC codes for the protection of intermediate channels of polar codes is proposed in this paper. Between two constituent codes, a specifically designed interleaver is employed such that the overall error probability is minimized. The extrinsic information transfer (EXIT) analysis and a low-complexity heuristic method are proposed for the interleaver design. The soft cancellation (SCAN) and belief propagation(BP) algorithms are employed for the decoding of concatenated codes. Simulations are provided to validate its advantages in terms of excellent error correction capability and low decoding complexity.