In this paper,we aim to design a practical low complexity low-density parity-check(LDPC)coded scheme to build a secure open channel and protect information from eavesdropping.To this end,we first propose a punctured L...In this paper,we aim to design a practical low complexity low-density parity-check(LDPC)coded scheme to build a secure open channel and protect information from eavesdropping.To this end,we first propose a punctured LDPC coded scheme,where the information bits in a codeword are punctured and only the parity check bits are transmitted to the receiver.We further propose a notion of check node type distribution and derive multi-edge type extrinsic information transfer functions to estimate the security performance,instead of the well-known weak metric bit error rate.We optimize the check node type distribution in terms of the signal-to-noise ratio(SNR)gap and modify the progressive edge growth algorithm to design finite-length codes.Numerical results show that our proposed scheme can achieve a lower computational complexity and a smaller security gap,compared to the existing scrambling and puncturing schemes.展开更多
Free-space optical(FSO)communication is of supreme importance for designing next-generation networks.Over the past decades,the radio frequency(RF)spectrum has been the main topic of interest for wireless technology.Th...Free-space optical(FSO)communication is of supreme importance for designing next-generation networks.Over the past decades,the radio frequency(RF)spectrum has been the main topic of interest for wireless technology.The RF spectrum is becoming denser and more employed,making its availability tough for additional channels.Optical communication,exploited for messages or indications in historical times,is now becoming famous and useful in combination with error-correcting codes(ECC)to mitigate the effects of fading caused by atmospheric turbulence.A free-space communication system(FSCS)in which the hybrid technology is based on FSO and RF.FSCS is a capable solution to overcome the downsides of current schemes and enhance the overall link reliability and availability.The proposed FSCS with regular low-density parity-check(LDPC)for coding techniques is deliberated and evaluated in terms of signal-to-noise ratio(SNR)in this paper.The extrinsic information transfer(EXIT)methodology is an incredible technique employed to investigate the sum-product decoding algorithm of LDPC codes and optimize the EXIT chart by applying curve fitting.In this research work,we also analyze the behavior of the EXIT chart of regular/irregular LDPC for the FSCS.We also investigate the error performance of LDPC code for the proposed FSCS.展开更多
Two modified BP algorithms related to vertical and horizontal processes are proposed to accelerate iterative low-density parity- check (LDPC) decoding over an additive white Gaussian noise (AWGN) channel, where th...Two modified BP algorithms related to vertical and horizontal processes are proposed to accelerate iterative low-density parity- check (LDPC) decoding over an additive white Gaussian noise (AWGN) channel, where the newly updated extrinsic information is immediately used in the current decoding round. Theoretical analysis and simulation results demonstrate that both the modified approaches provide significant performance improvements over the traditional BP algorithm with almost no additional decoding complexity. The proposed algorithm with modified horizontal process offers even better performance than another algorithm with the modified horizontal process. The two modified BP algorithms are very promising in practical communications since both can achieve an excellent trade-off between the performance and decoding complexity.展开更多
The 16-ary quadrature amplitude modulation (16QAM) is a high spectral efficient scheme for high-speed transmission systems. To remove the phase ambiguity in the coherent detection system, differential-encoded 16QAM ...The 16-ary quadrature amplitude modulation (16QAM) is a high spectral efficient scheme for high-speed transmission systems. To remove the phase ambiguity in the coherent detection system, differential-encoded 16QAM (DE-16QAM) is usually used, however, it will cause performance degradation about 3 dB as compared to the conventional 16QAM. To overcome the performance loss, a serial concatenated system with outer low density parity check (LDPC) codes and inner DE-16QAM is proposed. At the receiver, joint iterative differential demodulation and decoding (ID) is carried out to approach the maximum likelihood performance. Moreover, a genetic evolution algorithm based on the extrinsic information transfer chart is proposed to optimize the degree distribution of the outer LDPC codes. Both theoretical analyses and simulation results indicate that this algorithm not only compensates the performance loss, but also obtains a significant performance gain, which is up to 1 dB as compared to the conventional non-DE-16QAM.展开更多
It is well known that turbo decoding always begins from the first component decoder and supposes that the apriori information is '0' at the first iterative decoding. To alternatively start decoding at two comp...It is well known that turbo decoding always begins from the first component decoder and supposes that the apriori information is '0' at the first iterative decoding. To alternatively start decoding at two component decoders, we can gain two soft output values for the received observation of an input bit. It is obvious that two soft output values comprise more sufficient extrinsic information than only one output value obtained in the conventional scheme since different start points of decoding result in different combinations of the a priori information and the input codewords with different symbol orders due to the permutation of an interleaver. Summarizing two soft output values for erery bit before making hard decisions, we can correct more errors due to their complement. Consequently, turbo codes can achieve better error correcting performance than before in this way. Simulation results show that the performance of turbo codes using the novel proposed decoding scheme can get a growing improvement with the increment of SNR in general compared to the conventional scheme. When the bit error probability is 10-5 , the proposed scheme can achieve 0.5 dB asymptotic coding gain or so under the given simulation conditions.展开更多
Iterative demodulation and decoding scheme is analyzed and modulation labeling is considered to be one of the crucial factors to this scheme. By analyzing the existent mapping design criterion, four aspects are found ...Iterative demodulation and decoding scheme is analyzed and modulation labeling is considered to be one of the crucial factors to this scheme. By analyzing the existent mapping design criterion, four aspects are found as the key techniques for choosing a label mapping. Based on this discovery, a novel mapping design criteflon is proposed and two label mappings are searched according to it. Simulation results show that the performance of BICM-ID using the novel mappings is better than the former ones. The extrinsic information transfer (EXIT) chart is introduced and it is used to evaluate the proposed mapping design criteria.展开更多
In this paper, the Multiple Input Multiple Output (MIMO) doubly-iterative receiver which consists of the Probabilistic Data Association detector (PDA) and Low-Density Parity-Check Code (LDPC) decoder is developed. The...In this paper, the Multiple Input Multiple Output (MIMO) doubly-iterative receiver which consists of the Probabilistic Data Association detector (PDA) and Low-Density Parity-Check Code (LDPC) decoder is developed. The receiver performs two iterative decoding loops. In the outer loop, the soft information is exchanged between the PDA detector and the LDPC decoder. In the inner loop, it is exchanged between variable node and check node decoders inside the LDPC decoder. On the light of the Extrinsic Information Transfer (EXIT) chart technique, an LDPC code degree profile optimization algorithm is developed for the doubly-iterative receiver. Simulation results show the doubly-receiver with optimized irregular LDPC code can have a better performance than the one with the regular one.展开更多
The Q-ary low-density parity-check(LDPC) coded high order partial response continuous phase modulation(PR-CPM) with double iterative loops is investigated. This scheme shows significant improvements in power and b...The Q-ary low-density parity-check(LDPC) coded high order partial response continuous phase modulation(PR-CPM) with double iterative loops is investigated. This scheme shows significant improvements in power and bandwidth efficiency, but at the expense of long iterative decoding delay and computational complexity induced by the improper match between the demodulator and the decoder. To address this issue, the convergence behavior of Q-ary LDPC coded CPM is investigated for the Q=2 and Q〉2 cases, and an optimized design method based on the extrinsic information transfer chart is proposed to improve the systematic iterative efficiency. Simulation results demonstrate that the proposed method can achieve a perfect tradeoff between iterative decoding delay and bit error rate performance to satisfy real-time applications.展开更多
Today the error correcting codes are present in all the telecom standards, in particular the low density parity check (LDPC) codes. The choice of a good code for a given network is essentially linked to the decoding p...Today the error correcting codes are present in all the telecom standards, in particular the low density parity check (LDPC) codes. The choice of a good code for a given network is essentially linked to the decoding performance obtained by the bit error rate (BER) curves. This approach requires a significant simulation time proportional to the length of the code, to overcome this problem Exit chart was introduced, as a fast technique to predict the performance of a particular class of codes called Turbo codes. In this paper, we success to apply Exit chart to analyze convergence behavior of iterative threshold decoding of one step majority logic decodable (OSMLD) codes. The iterative decoding process uses a soft-input soft-output threshold decoding algorithm as component decoder. Simulation results for iterative decoding of simple and concatenated codes transmitted over a Gaussian channel have shown that the thresholds obtained are a good indicator of the Bit Error Rate (BER) curves.展开更多
In this paper,we present a new class of spatially coupled codes obtained by using both non-recursive and recursive block-oriented superposition.The resulting codes are termed as bidirectional block Markov superpositio...In this paper,we present a new class of spatially coupled codes obtained by using both non-recursive and recursive block-oriented superposition.The resulting codes are termed as bidirectional block Markov superposition transmission(BiBMST)codes.Firstly,we perform an iterative decoding threshold analysis according to protograph-based extrinsic information transfer(PEXIT)charts for the BiBMST codes over the binary erasure channels(BECs).Secondly,we derive the generator and parity-check matrices of the BiBMST codes.Thirdly,extensive numerical results are presented to show the advantages of the proposed BiBMST codes.Particularly,our numerical results show that,under the constraint of an equal decoding latency,the BiBMST codes perform better than the recursive BMST(rBMST)codes.However,the simulation results show that,in finite-length regime,negligible performance gain is obtained by increasing the encoding memory.We solve this limitation by introducing partial superposition,and the resulting codes are termed as partially-connected BiBMST(PC-BiBMST)code.Analytical results have confirmed the advantages of the PC-BiBMST codes over the original BiBMST codes.We also present extensive simulation results to show the performance advantages of the PC-BiBMST codes over the spatially coupled low-density parity-check(SC-LDPC)codes,spatially coupled generalized LDPC(SC-GLDPC)codes,and the original BiBMST codes in the finite-length regime.展开更多
When implementing helicopter-satellite communications, periodical interruption of the received signal is a challenging problem because the communication antenna is intermittently blocked by the rotating blades of the ...When implementing helicopter-satellite communications, periodical interruption of the received signal is a challenging problem because the communication antenna is intermittently blocked by the rotating blades of the helicopter. The helicopter-satellite channel model and the Forward Error Control(FEC) coding countermeasure are presented in this paper. On the basis of this model, Check-Hybrid(CH) Low-Density Parity-Check(LDPC)codes are designed to mitigate the periodical blockage over the helicopter-satellite channels. The CH-LDPC code is derived by replacing part of single parity-check code constraints in a Quasi-Cyclic LDPC(QC-LDPC) code by using more powerful linear block code constraints. In particular, a method of optimizing the CH-LDPC code ensemble by searching the best matching component code among a variety of linear block codes using extrinsic information transfer charts is proposed. Simulation results show that, the CH-LDPC coding scheme designed for the helicopter-satellite channels in this paper achieves more than 25% bandwidth efficiency improvement, compared with the FEC scheme that uses QC-LDPC codes.展开更多
文摘In this paper,we aim to design a practical low complexity low-density parity-check(LDPC)coded scheme to build a secure open channel and protect information from eavesdropping.To this end,we first propose a punctured LDPC coded scheme,where the information bits in a codeword are punctured and only the parity check bits are transmitted to the receiver.We further propose a notion of check node type distribution and derive multi-edge type extrinsic information transfer functions to estimate the security performance,instead of the well-known weak metric bit error rate.We optimize the check node type distribution in terms of the signal-to-noise ratio(SNR)gap and modify the progressive edge growth algorithm to design finite-length codes.Numerical results show that our proposed scheme can achieve a lower computational complexity and a smaller security gap,compared to the existing scrambling and puncturing schemes.
文摘Free-space optical(FSO)communication is of supreme importance for designing next-generation networks.Over the past decades,the radio frequency(RF)spectrum has been the main topic of interest for wireless technology.The RF spectrum is becoming denser and more employed,making its availability tough for additional channels.Optical communication,exploited for messages or indications in historical times,is now becoming famous and useful in combination with error-correcting codes(ECC)to mitigate the effects of fading caused by atmospheric turbulence.A free-space communication system(FSCS)in which the hybrid technology is based on FSO and RF.FSCS is a capable solution to overcome the downsides of current schemes and enhance the overall link reliability and availability.The proposed FSCS with regular low-density parity-check(LDPC)for coding techniques is deliberated and evaluated in terms of signal-to-noise ratio(SNR)in this paper.The extrinsic information transfer(EXIT)methodology is an incredible technique employed to investigate the sum-product decoding algorithm of LDPC codes and optimize the EXIT chart by applying curve fitting.In this research work,we also analyze the behavior of the EXIT chart of regular/irregular LDPC for the FSCS.We also investigate the error performance of LDPC code for the proposed FSCS.
基金National Mobile Communication Research Laboratory,Southeast University(No.W200704),ChinaNatural Science foundation of Jiangsu Province (No.BK2006188),ChinaQuebec-China Joint Research Foundation by McGill University,Montreal,Quebec,Canada
文摘Two modified BP algorithms related to vertical and horizontal processes are proposed to accelerate iterative low-density parity- check (LDPC) decoding over an additive white Gaussian noise (AWGN) channel, where the newly updated extrinsic information is immediately used in the current decoding round. Theoretical analysis and simulation results demonstrate that both the modified approaches provide significant performance improvements over the traditional BP algorithm with almost no additional decoding complexity. The proposed algorithm with modified horizontal process offers even better performance than another algorithm with the modified horizontal process. The two modified BP algorithms are very promising in practical communications since both can achieve an excellent trade-off between the performance and decoding complexity.
基金supported by the National Natural Science Foundation of China(61171101)the State Major Science and Technology Special Projects(2009ZX03003-011-03)
文摘The 16-ary quadrature amplitude modulation (16QAM) is a high spectral efficient scheme for high-speed transmission systems. To remove the phase ambiguity in the coherent detection system, differential-encoded 16QAM (DE-16QAM) is usually used, however, it will cause performance degradation about 3 dB as compared to the conventional 16QAM. To overcome the performance loss, a serial concatenated system with outer low density parity check (LDPC) codes and inner DE-16QAM is proposed. At the receiver, joint iterative differential demodulation and decoding (ID) is carried out to approach the maximum likelihood performance. Moreover, a genetic evolution algorithm based on the extrinsic information transfer chart is proposed to optimize the degree distribution of the outer LDPC codes. Both theoretical analyses and simulation results indicate that this algorithm not only compensates the performance loss, but also obtains a significant performance gain, which is up to 1 dB as compared to the conventional non-DE-16QAM.
文摘It is well known that turbo decoding always begins from the first component decoder and supposes that the apriori information is '0' at the first iterative decoding. To alternatively start decoding at two component decoders, we can gain two soft output values for the received observation of an input bit. It is obvious that two soft output values comprise more sufficient extrinsic information than only one output value obtained in the conventional scheme since different start points of decoding result in different combinations of the a priori information and the input codewords with different symbol orders due to the permutation of an interleaver. Summarizing two soft output values for erery bit before making hard decisions, we can correct more errors due to their complement. Consequently, turbo codes can achieve better error correcting performance than before in this way. Simulation results show that the performance of turbo codes using the novel proposed decoding scheme can get a growing improvement with the increment of SNR in general compared to the conventional scheme. When the bit error probability is 10-5 , the proposed scheme can achieve 0.5 dB asymptotic coding gain or so under the given simulation conditions.
文摘Iterative demodulation and decoding scheme is analyzed and modulation labeling is considered to be one of the crucial factors to this scheme. By analyzing the existent mapping design criterion, four aspects are found as the key techniques for choosing a label mapping. Based on this discovery, a novel mapping design criteflon is proposed and two label mappings are searched according to it. Simulation results show that the performance of BICM-ID using the novel mappings is better than the former ones. The extrinsic information transfer (EXIT) chart is introduced and it is used to evaluate the proposed mapping design criteria.
基金Supported by the National Natural Science Foundation of China (No. 60772061)Science Foundation of Nanjing University of Posts and Telecommunications (No. NY207132)
文摘In this paper, the Multiple Input Multiple Output (MIMO) doubly-iterative receiver which consists of the Probabilistic Data Association detector (PDA) and Low-Density Parity-Check Code (LDPC) decoder is developed. The receiver performs two iterative decoding loops. In the outer loop, the soft information is exchanged between the PDA detector and the LDPC decoder. In the inner loop, it is exchanged between variable node and check node decoders inside the LDPC decoder. On the light of the Extrinsic Information Transfer (EXIT) chart technique, an LDPC code degree profile optimization algorithm is developed for the doubly-iterative receiver. Simulation results show the doubly-receiver with optimized irregular LDPC code can have a better performance than the one with the regular one.
基金supported by the National Natural Science Foundation of China(61403093)the Science Foundation of Heilongjiang Province of China for Returned Scholars(LC2013C22)the Assisted Project by Heilongjiang Province of China Postdoctoral Funds for Scientific Research Initiation(LBH-Q14048)
文摘The Q-ary low-density parity-check(LDPC) coded high order partial response continuous phase modulation(PR-CPM) with double iterative loops is investigated. This scheme shows significant improvements in power and bandwidth efficiency, but at the expense of long iterative decoding delay and computational complexity induced by the improper match between the demodulator and the decoder. To address this issue, the convergence behavior of Q-ary LDPC coded CPM is investigated for the Q=2 and Q〉2 cases, and an optimized design method based on the extrinsic information transfer chart is proposed to improve the systematic iterative efficiency. Simulation results demonstrate that the proposed method can achieve a perfect tradeoff between iterative decoding delay and bit error rate performance to satisfy real-time applications.
文摘Today the error correcting codes are present in all the telecom standards, in particular the low density parity check (LDPC) codes. The choice of a good code for a given network is essentially linked to the decoding performance obtained by the bit error rate (BER) curves. This approach requires a significant simulation time proportional to the length of the code, to overcome this problem Exit chart was introduced, as a fast technique to predict the performance of a particular class of codes called Turbo codes. In this paper, we success to apply Exit chart to analyze convergence behavior of iterative threshold decoding of one step majority logic decodable (OSMLD) codes. The iterative decoding process uses a soft-input soft-output threshold decoding algorithm as component decoder. Simulation results for iterative decoding of simple and concatenated codes transmitted over a Gaussian channel have shown that the thresholds obtained are a good indicator of the Bit Error Rate (BER) curves.
基金supported by the National Natural Science Foundation of China(Nos.62271233,12271215,and 62261003)the Basic Research Program of Guangzhou Municipal Science and Technology Bureau(No.202201020036)the Guangdong Provincial Natural Science Foundation(Nos.2022A1515010029 and 2021A1515011906).
文摘In this paper,we present a new class of spatially coupled codes obtained by using both non-recursive and recursive block-oriented superposition.The resulting codes are termed as bidirectional block Markov superposition transmission(BiBMST)codes.Firstly,we perform an iterative decoding threshold analysis according to protograph-based extrinsic information transfer(PEXIT)charts for the BiBMST codes over the binary erasure channels(BECs).Secondly,we derive the generator and parity-check matrices of the BiBMST codes.Thirdly,extensive numerical results are presented to show the advantages of the proposed BiBMST codes.Particularly,our numerical results show that,under the constraint of an equal decoding latency,the BiBMST codes perform better than the recursive BMST(rBMST)codes.However,the simulation results show that,in finite-length regime,negligible performance gain is obtained by increasing the encoding memory.We solve this limitation by introducing partial superposition,and the resulting codes are termed as partially-connected BiBMST(PC-BiBMST)code.Analytical results have confirmed the advantages of the PC-BiBMST codes over the original BiBMST codes.We also present extensive simulation results to show the performance advantages of the PC-BiBMST codes over the spatially coupled low-density parity-check(SC-LDPC)codes,spatially coupled generalized LDPC(SC-GLDPC)codes,and the original BiBMST codes in the finite-length regime.
基金supported by the National Natural Science Foundation of China(No.91538203)the new strategic industries development projects of Shenzhen City(No.JCYJ20150403155812833)
文摘When implementing helicopter-satellite communications, periodical interruption of the received signal is a challenging problem because the communication antenna is intermittently blocked by the rotating blades of the helicopter. The helicopter-satellite channel model and the Forward Error Control(FEC) coding countermeasure are presented in this paper. On the basis of this model, Check-Hybrid(CH) Low-Density Parity-Check(LDPC)codes are designed to mitigate the periodical blockage over the helicopter-satellite channels. The CH-LDPC code is derived by replacing part of single parity-check code constraints in a Quasi-Cyclic LDPC(QC-LDPC) code by using more powerful linear block code constraints. In particular, a method of optimizing the CH-LDPC code ensemble by searching the best matching component code among a variety of linear block codes using extrinsic information transfer charts is proposed. Simulation results show that, the CH-LDPC coding scheme designed for the helicopter-satellite channels in this paper achieves more than 25% bandwidth efficiency improvement, compared with the FEC scheme that uses QC-LDPC codes.