Method and polar code decoder for determining to-be-flipped bit position

A polar code decoder, comprising:

• a storage circuit, storing a plurality of modules;
• and
• a processor, coupled to the storage circuit and accessing the modules to perform:
• obtaining a polar code decoding tree, wherein the polar code decoding tree is generated by performing a successive cancellation list (SCL) operation on a polar code segment, wherein the polar code segment comprises a plurality of bit positions, and each of the bit positions comprises a plurality of surviving paths and a plurality of pruned paths in the polar code decoding tree;
• in a post-processing stage of the SCL operation, for an i-th bit position among the bit positions, estimating a correct path probability of each of the surviving paths and the pruned paths of the i-th bit position and accordingly estimating a reliability of the i-th bit position;
• selecting a first specific bit position among the bit positions as a to-be-flipped bit position based on the reliability of each of the bit positions;
• and
• performing an SCL flip operation on the polar code decoding tree based on the first specific bit position.