Title: An Improved SCFlip Decoder for Polar Codes,
Abstract: This paper focuses on the recently introduced Successive Cancellation Flip
(SCFlip) decoder of polar codes. Our contribution is twofold. First, we propose
the use of an optimized metric to determine the flipping positions within the
SCFlip decoder, which improves its ability to find the first error that
occurred during the initial SC decoding attempt. We also show that the proposed
metric allows closely approaching the performance of an ideal SCFlip decoder.
Second, we introduce a generalisation of the SCFlip decoder to a number of
$\omega$ nested flips, denoted by SCFlip-$\omega$, using a similar optimized
metric to determine the positions of the nested flips. We show that the
SCFlip-2 decoder yields significant gains in terms of decoding performance and
competes with the performance of the CRC-aided SC-List decoder with list size
L=4, while having an average decoding complexity similar to that of the
standard SC decoding, at medium to high signal to noise ratio.