Efficient Blind Detection Scheme Based on Simplified Decoding of Polar Codes

In blind detection, both the downlink control information (DCI) format and the physical downlink control channel format are unknown, which results in high detection complexity. If the DCI format can be determined, half of the invalid candidates will be eliminated, which can significantly reduce the detection complexity. To determine the DCI format, this letter designs a DCI metric based on a correction factor of the transition probability, which is capable of measuring the reliability of decoding paths with different number of frozen bits. Furthermore, to reduce the decoding latency, a simplified decoding algorithm is adopted in the proposed blind detection scheme, which shows good adaptivity for a variety of code lengths and code rates. Moreover, an update criterion of the DCI metric based on the simplified decoding method is proposed, which improves the detection accuracy and reduces the decoding latency. Simulation results show the advantages of the proposed method in terms of the detection performance and latency compared with the existing schemes.