Reliability-Design of Ordered Tree-Based Single-Parity-Check Decoder for Polar Codes Fast List Decoding

The fifth-generation Internet of Things (5G-IoT) requires more capable channel coding methods to obtain low-latency and high-reliability communication systems. Hence, an improved ordered tree-based single-parity-check (OT-SPC) list decoder for polar code is designed in this article to reduce the complexity and keep the reliability. The proposed method introduces the ordered error pattern set of the single-parity-check (SPC) list decoder, which collects all the necessary error patterns. We first define a relationship between these patterns and present the concepts of the necessary error pattern and the ordered error pattern set. Then, we adapt the ordered tree data structure and the asynchronous tournament sorters to relieve the complexity increase of the ordered error pattern set's introduction. The reliability relationships of different patterns are stored in an ordered tree, and the tournament sorting algorithm is modified separately for the log-likelihood ratio values of the received sequence and the path metrics of the decoding paths. In this scheme, the candidate codewords of the SPC list decoder are constructed in the descending order of their probability, which significantly reduces the calculation and comparison consumption. Eventually, the results show that the OT-SPC list decoder obtains a superior performance in decoding throughput and latency while preserving the error-correction performance.