Method and apparatus for decoding and checking tail-biting convolutional code

摘要

A method for decoding and checking a tail-biting convolutional code is provided. The method fully utilizes structural features of the tail-biting convolutional code to re-sort Log-Likelihood Ratio (LLR) values input into a decoder, and by reconstructing a derivative generator polynomial of a convolutional code, allows the decoder to output in serial according to a normal ordering of information bits during backtracking, that is, a first bit of an information sequence is first decoded successfully. Thus, CRC checking may be activated as soon as possible, so that part of the backtracking process and the CRC checking may be performed in parallel, thereby achieving the objective of reducing a processing time delay in decoding and checking the tail-biting convolutional code.

主权项

1. A method for decoding and checking a tail-biting convolutional code by a processor, comprising:
re-sorting M routes of log-likelihood ratios rm(i) obtained after de-interleaving to obtain rm(i), wherein rm(i)=rm[(C−1−i+W) mod C], and inputting rm(i) into a decoder, wherein m=0, 1, M−1, i=0, 1, . . . , C−1, W represents a number of registers of the tail-biting convolutional code, and C represents an information bit length of the tail-biting convolutional code; constructing a derivative sequence of a generator polynomial sequence of the tail-biting convolutional code, and performing forward path searching on the rm(i) obtained after re-sorting, wherein the derivative sequence is an inverse sequence of the generator polynomial sequence of the tail-biting convolutional code; and performing optimal path backtracking on a path with a largest state metric value in the forward path searching to obtain results of decoding the tail-biting convolutional code, and activating Cyclic Redundancy Check (CRC) checking of the results of decoding the tail-biting convolutional code during the optimal path backtracking; the method further comprising: reporting downlink control information obtained by decoding if the results of decoding the tail-biting convolutional code pass the CRC checking, otherwise discarding the results of decoding.