Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

IEEE International Conference on Control Science and Systems Engineering (ICCSSE)

An Improved Bit-Flipping Based Decoding Algorithm for Polar Codes

Xiao Hu, Shufeng Li, Mingyu Cai

Published Jul 30, 2021• 2 citations
Publisher

Abstract

In this paper, we propose three improved bit flipping algorithms in successive cancellation (SC) decoding and successive cancellation list (SCL) decoding. Weighted single-bit flipping successive cancellation (WSFSC) decoding first performs SC decoding on the output sequence, T bits with the smallest product of channel capacity and absolute value of LLR are regarded as unreliable bits. In multi-bit flipping successive cancellation (MFSC) algorithm, the unreliable bits are respectively corrected according to the single-bit flipping and multi-bit flipping rules. In single flipping successive cancellation list (SFSCL) algorithm, by subtracting a large penalty value from the path metric (PM) value of the unreliable bit, the decoding path corresponding to this bit is more likely to be pruned during path screening, so as to realize bit flipping indirectly. Simulation results show that the proposed WSFSC and MFSC algorithm has a gain of 0.3dB compared with the traditional SC algorithm, SFSCL algorithm has a gain of 0.3dB compared with the traditional SCL algorithm.

DOI
10.1109/iccsse52761.2021.9545101

Related papers

An LLR-Based Segmented Flipped SCL Decoding Algorithm for Polar Codes

Anqi Cao, Li Guo Zhang, Jian Qiao +1 more

Polar codes have attracted significant attention in the field of communication, for the capacity-achieving under binary-input discrete memoryless channels (BDMCs). On the basis of successive cancellation (SC) decoding algorithm, many excellent methods have been developed to improve the decoding performance on short and medium codes. In this paper, an LLR-based segmented flipped successive cancellation list (LLR-based SF-SCL) decoding algorithm is proposed, where the information bits are divided into segments for early bit-flipping and termination. In order to make the unreliable bits evenly distributed in each sub-block, an LLR-based segmentation scheme is applied. Simulation results show that the proposed segmented flipped algorithm is superior to CRC-aided successive cancellation list (CA-SCL) algorithm in the block error rate (BLER) performance, and LLR-based segmentation scheme has better performance compared to uniform segmentation scheme.

IEEE/CIC International Conference on Communications in China (ICCC)•Aug 1, 2019•9 citations

An Improved Multiple Bit-Flipping Successive Cancellation Decoding Algorithm for Polar Codes

Sha Sha, Li Guo Zhang, Yejun He

Although original successive cancellation flip (SCF) decoding of the polar codes can identify the first error position and flip the error, decoding still fails when other errors occur after the corrected error bit. Therefore, the improvement of the block error rate (BLER) performance is limited. In this paper, we present an improved algorithm that can correct multiple error bits, named as improved multiple bit-flipping successive cancellation decoding algorithm. First, multiple sets are constructed by calculating the log likelihood ratio (LLR) of each information bit. Then, a bit is selected and corrected from the first set when original decoding fails; two bits are selected and flipped from the second set when all bits in the first set cannot be successfully decoded; when all bits combinations in the second set are flipped but the output vector still does not match the input vector, three bits are selected and corrected from the third set. Simulation results show that the BLER performance of the improved algorithm is better than that of the successive cancellation list decoding (SCL) decoding algorithm with a list size of L = 8 for N = 256. When N = 1024 and SNR = 3 dB, the BLER performance of improved algorithm is slightly better than that of SCL decoding algorithm with a list size of L = 4.

International Conference on Wireless Communications and Signal Processing (WCSP)•Oct 21, 2020•1 citation

An Improved Belief Propagation Bit-Flipping Decoder for Polar Codes

Mengqing Zhao, Daqin Peng

Bit flipping was first used to improve the decoding performance of successive cancellation (SC) decoder. Since SC decoding process is serial, so the first bit that goes wrong in the decoding process will cause several subsequent bits to go wrong, which will suffer from higher decoding delay than belief propagation (BP) parallel decoding. In order to meet the performance of 5G low latency and high reliability, BP decoding algorithm have received a lot of attention. However, at medium and high signal-to-noise ratios (SNR), BP decoding does not perform as well as the SC list (SCL) decoding algorithm. Hence, BP decoding algorithm borrows bit-flip strategies from SC bit flip (SCF) decoder to improve the performance. The performance of BP bit flip (BPF) decoding depends on whether the construction of the flip set is correct, so this letter proposes a flip set construction approach based on the standard deviation of the log-likelihood ratio (LLR) and the reliability weight of polarized channels, which is comparable to the existing BPF decoding, the improved algorithm can identify the error-prone bits more efficiently and improve the decoding performance.

International Conference on Intelligent Computing and Signal Processing (ICSP)•Apr 21, 2023•2 citations

Bit Metrics Based on SCLF Decoding Algorithm for Polar Codes

Haifeng Lin, Rui Guo

As an indispensable part of cyclic redundancy check aided Successive Cancellation List (CA-SCL) decoding and SCL bit flipping (CA-SCLF) decoding, sort operation increases the complexity of decoding.In order to minimize the quantity of sorting and simplify the complexity of SCLF decoding algorithm, this paper proposes an improved SCLF decoding algorithm, called NSCLF algorithm, which reduces the number of paths involved in sorting by detecting and pruning paths whose bit metric value is less than the set threshold before sorting operations.Meanwhile, pruning paths are dynamically selected according to node states during the flipping process.The flipping path selections are more accurate and the number of flipping correspondingly decreases.The simulation results demonstrate that when SNR is 3dB, the code length and code rate , while maintaining decoding performance comparable to that of traditional CA-SCLF, the sorting operation of our proposed NSCLF is about 93% less than that of traditional CA-SCLF, and the decoding complexity is less than that of traditional CA-SCLF.

KSII Transactions on Internet and Information Systems•May 31, 2025•0 citations

Generalized SCL-Flip Decoding of Polar Codes

Yaoxin Pan, Chung-Hsuan Wang, Yeong-Luh Ueng

In this paper, two improvements for successive cancellation list flip (SCL-Flip) decoding are presented for polar codes. First, a novel bit-selection metric based on path metric (PM) is introduced. With the proposed metric, the improved scheme can have lower complexity and saturate faster than other state-of-the-art decoders. Second, we generalize the SCL-Flip decoding, denoted SCL-Flip-ω, to flip the decision in path competition at most ω times in decoding process. We analyze the frequency of channel-induced error under various circumstances, measure the trade-off between error-correction performance and complexity, and then propose SCL-Flip-2 decoding which is the first SCL-based decoding that allows for multiple bits for flipping to the best of our knowledge. Simulation results reveal that the proposed decoding with a small list size can achieve a better performance than CA-SCL decoding with a large list size while keeping the complexity low.

Globecom•Dec 1, 2020•18 citations

Algorithm and Architecture for Path Metric Aided Bit-Flipping Decoding of Polar Codes

Yu Wang, Lirui Chen, Qinglin Wang +2 more

Polar codes attract more and more attention of researchers in recent years, since its capacity achieving property. However, their error-correction performance under successive cancellation (SC) decoding is inferior to other modern channel codes at short or moderate blocklengths. SC-Flip (SCF) decoding algorithm shows higher performance than SC decoding by identifying possibly erroneous decisions made in initial SC decoding and flipping them in the sequential decoding attempts. However, it performs not well when there are more than one erroneous decisions in a codeword. In this paper, we propose a path metric aided bit-flipping decoding algorithm to identify and correct more errors efficiently. In this algorithm, the bit-flipping list is generated based on both log likelihood ratio (LLR) based path metric and bit-flipping metric. The path metric is used to verify the effectiveness of bit-flipping. In order to reduce the decoding latency and computational complexity, its corresponding pipeline architecture is designed. By applying these decoding algorithm and pipeline architecture, an improvement on error-correction performance can be got up to 0.25dB compared with SCF decoding at frame error rate of 10-4, with low average decoding latency.

arXiv:1903.03381•IEEE Wireless Communications and Networking Conference•Apr 1, 2019•8 citations
In this paper, we propose three improved bit flipping algorithms in successive cancellation (SC) decoding and successive cancellation list (SCL) decoding. Weighted single-bit flipping successive cancellation (WSFSC) decoding first performs SC decoding on the output sequence, T bits with the smallest product of channel capacity and absolute value of LLR are regarded as unreliable bits. In multi-bit flipping successive cancellation (MFSC) algorithm, the unreliable bits are respectively corrected according to the single-bit flipping and multi-bit flipping rules. In single flipping successive cancellation list (SFSCL) algorithm, by subtracting a large penalty value from the path metric (PM) value of the unreliable bit, the decoding path corresponding to this bit is more likely to be pruned during path screening, so as to realize bit flipping indirectly. Simulation results show that the proposed WSFSC and MFSC algorithm has a gain of 0.3dB compared with the traditional SC algorithm, SFSCL algorithm has a gain of 0.3dB compared with the traditional SCL algorithm.
Polar codes have attracted significant attention in the field of communication, for the capacity-achieving under binary-input discrete memoryless channels (BDMCs). On the basis of successive cancellation (SC) decoding algorithm, many excellent methods have been developed to improve the decoding performance on short and medium codes. In this paper, an LLR-based segmented flipped successive cancellation list (LLR-based SF-SCL) decoding algorithm is proposed, where the information bits are divided into segments for early bit-flipping and termination. In order to make the unreliable bits evenly distributed in each sub-block, an LLR-based segmentation scheme is applied. Simulation results show that the proposed segmented flipped algorithm is superior to CRC-aided successive cancellation list (CA-SCL) algorithm in the block error rate (BLER) performance, and LLR-based segmentation scheme has better performance compared to uniform segmentation scheme.
Although original successive cancellation flip (SCF) decoding of the polar codes can identify the first error position and flip the error, decoding still fails when other errors occur after the corrected error bit. Therefore, the improvement of the block error rate (BLER) performance is limited. In this paper, we present an improved algorithm that can correct multiple error bits, named as improved multiple bit-flipping successive cancellation decoding algorithm. First, multiple sets are constructed by calculating the log likelihood ratio (LLR) of each information bit. Then, a bit is selected and corrected from the first set when original decoding fails; two bits are selected and flipped from the second set when all bits in the first set cannot be successfully decoded; when all bits combinations in the second set are flipped but the output vector still does not match the input vector, three bits are selected and corrected from the third set. Simulation results show that the BLER performance of the improved algorithm is better than that of the successive cancellation list decoding (SCL) decoding algorithm with a list size of L = 8 for N = 256. When N = 1024 and SNR = 3 dB, the BLER performance of improved algorithm is slightly better than that of SCL decoding algorithm with a list size of L = 4.
Bit flipping was first used to improve the decoding performance of successive cancellation (SC) decoder. Since SC decoding process is serial, so the first bit that goes wrong in the decoding process will cause several subsequent bits to go wrong, which will suffer from higher decoding delay than belief propagation (BP) parallel decoding. In order to meet the performance of 5G low latency and high reliability, BP decoding algorithm have received a lot of attention. However, at medium and high signal-to-noise ratios (SNR), BP decoding does not perform as well as the SC list (SCL) decoding algorithm. Hence, BP decoding algorithm borrows bit-flip strategies from SC bit flip (SCF) decoder to improve the performance. The performance of BP bit flip (BPF) decoding depends on whether the construction of the flip set is correct, so this letter proposes a flip set construction approach based on the standard deviation of the log-likelihood ratio (LLR) and the reliability weight of polarized channels, which is comparable to the existing BPF decoding, the improved algorithm can identify the error-prone bits more efficiently and improve the decoding performance.
As an indispensable part of cyclic redundancy check aided Successive Cancellation List (CA-SCL) decoding and SCL bit flipping (CA-SCLF) decoding, sort operation increases the complexity of decoding.In order to minimize the quantity of sorting and simplify the complexity of SCLF decoding algorithm, this paper proposes an improved SCLF decoding algorithm, called NSCLF algorithm, which reduces the number of paths involved in sorting by detecting and pruning paths whose bit metric value is less than the set threshold before sorting operations.Meanwhile, pruning paths are dynamically selected according to node states during the flipping process.The flipping path selections are more accurate and the number of flipping correspondingly decreases.The simulation results demonstrate that when SNR is 3dB, the code length and code rate , while maintaining decoding performance comparable to that of traditional CA-SCLF, the sorting operation of our proposed NSCLF is about 93% less than that of traditional CA-SCLF, and the decoding complexity is less than that of traditional CA-SCLF.
In this paper, two improvements for successive cancellation list flip (SCL-Flip) decoding are presented for polar codes. First, a novel bit-selection metric based on path metric (PM) is introduced. With the proposed metric, the improved scheme can have lower complexity and saturate faster than other state-of-the-art decoders. Second, we generalize the SCL-Flip decoding, denoted SCL-Flip-ω, to flip the decision in path competition at most ω times in decoding process. We analyze the frequency of channel-induced error under various circumstances, measure the trade-off between error-correction performance and complexity, and then propose SCL-Flip-2 decoding which is the first SCL-based decoding that allows for multiple bits for flipping to the best of our knowledge. Simulation results reveal that the proposed decoding with a small list size can achieve a better performance than CA-SCL decoding with a large list size while keeping the complexity low.
Polar codes attract more and more attention of researchers in recent years, since its capacity achieving property. However, their error-correction performance under successive cancellation (SC) decoding is inferior to other modern channel codes at short or moderate blocklengths. SC-Flip (SCF) decoding algorithm shows higher performance than SC decoding by identifying possibly erroneous decisions made in initial SC decoding and flipping them in the sequential decoding attempts. However, it performs not well when there are more than one erroneous decisions in a codeword. In this paper, we propose a path metric aided bit-flipping decoding algorithm to identify and correct more errors efficiently. In this algorithm, the bit-flipping list is generated based on both log likelihood ratio (LLR) based path metric and bit-flipping metric. The path metric is used to verify the effectiveness of bit-flipping. In order to reduce the decoding latency and computational complexity, its corresponding pipeline architecture is designed. By applying these decoding algorithm and pipeline architecture, an improvement on error-correction performance can be got up to 0.25dB compared with SCF decoding at frame error rate of 10-4, with low average decoding latency.