Code Length Compatible Belief Propagation Polar Decoder Based on Folding and Unfolding

This paper presents a code-length compatible architecture for belief propagation (BP) polar decoders. This decoder incorporates folding and unfolding techniques with control signals, allowing it to decode codes with varying code lengths. By modifying the architecture originally designed for code length N, the proposed decoder can handle codes of length 2
ⁱ
N, where i ∈ Z
⁺
using folding, and i ∈ Z
⁻
using unfolding. To reduce the critical path and implementation complexity, a new routing design is proposed. Moreover, we introduce a memory architecture utilizing shift registers instead of RAM to increase the throughput. We demonstrate gate-level implementations to illustrate the design’s architecture. Finally, we analyze the throughput, area, and power consumption of the decoders. Compared with traditional single-column designs with N = 1024, the proposed decoder architecture can achieve up to 136% hardware efficiency while consuming 1.6% less area.