Research On HARQ System Of Polar Codes

Polar codes, recently introduced by Ankan, are the first constructable codes that have been proved to achieve the symmetric capacity on binary-input discrete memoryless channels so that polar codes fastly become a popular area of research. The polar codes have played an important role in the 5G mobile system. It is becoming increasingly important in the future mobile system. In order to achieve better performance for the communication systems based on polar codes, the link-adaptive technique based on polar codes is also an important research point. Therefore, we focus on the Hybrid Automatic Repeat Request (HARQ) technique based on polar codes and have done a series of research.In this paper, based on existing the HARQ system for the rate compatible puncture polar codes(RCPP), the HARQ system of polar codes is further researched and a framework of HARQ systems for polar codes is proposed for adapting the pratical communication systems. Concretely, some puncturing schemes and expending schemes are analyzed, and a pipeline HARQ scheme of polarcodes is proposed emphatically. The proposed pipeline HARQ scheme is designed more practically. And it is a versatile HARQ scheme of polar codes in which the throught is increased as well as the complexity is decreased.The simulation results show that the pipeline HARQ scheme has almost the same throughput as the RCPP-based incremental redundancy HARQ(HARQ-IR)scheme using the successive cancellation(SC) decoder. With similar throughput performance using the SC decoder, the number of retransmissions required for the pipeline HARQ scheme is fewer, and the delay and complexity of the system can be effectively reduced. At the same time, the pipelined HARQ scheme achieves higher throughput than the HARQ-IR based on RCPP when the CRC-aided successive cancellation list decoder is applied due to its simpler structure.