Improved Generalized Successive Cancellation List Flip Decoder of Polar Codes with Fast Decoding of Special Nodes

Fedor Ivanov, Valerii Morishnik, and Evgenii Krouk


Abstract : In this paper, an improvement for SC list flip (SCLFlip)decoding is presented for polar codes. A novel bit-selectionmetric for critical set (set of information symbols of polar codesbeing flipped during additional decoding attempts) based on pathmetric of successive cancellation list (SCL) decoding is suggested.With the proposed metric, the improved SCL scheme based onspecial nodes (SN) decoders was developed. This decoder willbe denoted by GSCLF. The main idea of the proposed decoderis joint using of two approaches: first one is a fast decoding ofspecial nodes in binary tree representation of polar code (e.g.,some special nodes in tree representation of polar code that allowefficient list decoding with low complexity) and the second oneis an applying of additional decoding attempts (flips) in the casewhen initial decoding was erroneous. The simultaneous use ofthese two approaches results in both a significant reduction inspatial complexity and a significant reduction in the number ofcomputations required for decoding whereas keeping excellentperformance. Simulation results presented in this paper allow usto conclude that the computational complexity of the proposedGSCLF decoder is from 66% to 80% smaller than the one ofSCL-32 decoder.​ 

Index terms : Polar codes, SCL-Flip decoding, subcodes of polar code, successive cancellation list decoding.