Optimized sorting network for successive cancellation list decoding of polar codes

Abstract

In this paper, we propose an optimized bitonic sorting architecture and a hybrid sorting architecture for addressing the sorting problem of successive cancellation list decoders for polar codes. Since half of the 2L metrics are already sorted, lots of redundant sorting operations can be deleted. According to this property and the characteristics of the sorting network, we put forward several optimization strategies to reduce the compare-and-exchange units and the pipeline depths. For the list size L ≤ 32, the synthesis results show that the area of proposed hybrid sorter is at least 22% smaller than existing sorters, and the latency is at least 25% smaller.