Practical Decoding for Deep Polar Codes

Pre-transformed polar codes constitute a broad class of codes constructed through the serial concatenation of outer codes and polar codes, enhancing the performance of standalone polar codes either by improving the weight distribution or by increasing the error-decay rate. Deep polar codes, a novel variant within this class, are constructed through a pre-transformation that involves a series of nested polar codes with increasing dimensions across layers. The proposed successive cancellation list with backpropagation parity check (SCL-BPC) decoder exploits the parity equations naturally arising from this nested encoding structure. In certain scenarios, deep polar codes with SCL-BPC decoding demonstrate superior performance compared to other pre-transformed polar codes. However, the SCL-BPC algorithm incurs additional decoding complexity and results in uneven decoding times. To address these issues, we investigate the matrix representation of the pre-transformation in deep polar codes and develop efficient implementation solutions for SCL-BPC decoding. Additionally, we introduce a low-complexity approach to SCL-BPC, which exhibits only a marginal reduction in performance.