Abstract: This paper propose a rate-compatible puncturing scheme for finite-length low-density parity-check (LDPC)codes over the additive white Gaussian noise (AWGN) channel.The method can applicable to both regular and irregular LDPC code.The scheme selects bits to be punctured base on a sequence of criteria．An important selection criterion is the number of short cycles with low approximate cycle extrinsic message degree (ACE) in which a candidate bit node participates.Simulation results demonstrate that the ACE plays an important role in the performance of the codes,these results also show that the scheme is superior to the existing puncturing methods in a wide range of code rates.

Key words: Low-density parity-check (LDPC) codes,Rate-compatible,Tanner graph,Puncturing,Finite-length,Approximate cycle extrinsic message degree (ACE)