Non-Uniform Quantization of Successive Cancellation List Decoder for Polar Codes

A good quantization scheme plays a tremendously important role in the hardware implementation of the decoder for polar codes. In this paper, a non-uniform quantization scheme for cyclic redundancy check aided successive-cancellation list (CA-SCL) decoder of polar codes is proposed to save memory resources. In the proposed non-uniform quantization scheme, we introduce a simple compression function to decrease the truncation threshold so that the soft information can be quantized with fewer quantization bits. The scaling factor in the compression function is a negative integer power of two, which can be efficiently implemented by shift operations. Then a compressed-domain CA-SCL decoder is derived, alleviating the need to decompress samples one-by-one. Simulation results show that on the condition of approaching floating-point performance, the internal log-likelihood ratio (LLR) memory resource consumption can be saved by 20% compared with uniform quantization.