Atmospheric absorption, scattering, and scintillation are the major causes to deteriorate the transmission quality of terahertz(THz) wireless communications. An error control coding scheme based on low density parit...Atmospheric absorption, scattering, and scintillation are the major causes to deteriorate the transmission quality of terahertz(THz) wireless communications. An error control coding scheme based on low density parity check(LDPC) codes with soft decision decoding algorithm is proposed to improve the bit-error-rate(BER) performance of an on-off keying(OOK) modulated THz signal through atmospheric channel. The THz wave propagation characteristics and channel model in atmosphere is set up. Numerical simulations validate the great performance of LDPC codes against the atmospheric fading and demonstrate the huge potential in future ultra-high speed beyond Gbps THz communications.展开更多
The application of protograph low density parity check (LDPC) codes involves the encoding complexity problem. Since the generator matrices are dense, and if the positions of "1" s are irregularity, the encoder nee...The application of protograph low density parity check (LDPC) codes involves the encoding complexity problem. Since the generator matrices are dense, and if the positions of "1" s are irregularity, the encoder needs to store every "1" of the generator matrices by using huge chip area. In order to solve this problem, we need to design the protograph LDPC codes with circular generator matrices. A theorem concerning the circulating property of generator matrices of nonsingular protograph LDPC codes is proposed. The circulating property of generator matrix of nonsingular protograph LDPC codes can be obtained from the corresponding quasi-cyclic parity check matrix. This paper gives a scheme of constructing protograph LDPC codes with circulating generator matrices, and it reveals that the fast encoding algorithm of protograph LDPC codes has lower encoding complexity under the condition of the proposed theorem. Simulation results in ad- ditive white Gaussian noise (AWGN) channels show that the bit error rate (BER) performance of the designed codes based on the proposed theorem is much better than that of GB20600 LDPC codes and Tanner LDPC codes.展开更多
Watermarking system based on quantization index modulation (QIM) is increasingly popular in high payload applications,but it is inherently fragile against amplitude scaling attacks.In order to resist desynchronizati...Watermarking system based on quantization index modulation (QIM) is increasingly popular in high payload applications,but it is inherently fragile against amplitude scaling attacks.In order to resist desynchronization attacks of QIM digital watermarking,a low density parity check (LDPC) code-aided QIM watermarking algorithm is proposed,and the performance of QIM watermarking system can be improved by incorporating LDPC code with message passing estimation/detection framework.Using the theory of iterative estimation and decoding,the watermark signal is decoded by the proposed algorithm through iterative estimation of amplitude scaling parameters and decoding of watermark.The performance of the proposed algorithm is closer to the dirty paper Shannon limit than that of repetition code aided algorithm when the algorithm is attacked by the additive white Gaussian noise.For constant amplitude scaling attacks,the proposed algorithm can obtain the accurate estimation of amplitude scaling parameters.The simulation result shows that the algorithm can obtain similar performance compared to the algorithm without desynchronization.展开更多
In this paper, we present a Joint Source-Channel Decoding algorithm (JSCD) for Low-Density Parity Check (LDPC) codes by modifying the Sum-Product Algorithm (SPA) to account for the source redun-dancy, which results fr...In this paper, we present a Joint Source-Channel Decoding algorithm (JSCD) for Low-Density Parity Check (LDPC) codes by modifying the Sum-Product Algorithm (SPA) to account for the source redun-dancy, which results from the neighbouring Huffman coded bits. Simulations demonstrate that in the presence of source redundancy, the proposed algorithm gives better performance than the Separate Source and Channel Decoding algorithm (SSCD).展开更多
This paper proposes a scheme to construct time- frequency codes based on protograph low density parity check (LDPC) codes in orthogonal frequency division multiplexing (OFDM) communication systems. This approach s...This paper proposes a scheme to construct time- frequency codes based on protograph low density parity check (LDPC) codes in orthogonal frequency division multiplexing (OFDM) communication systems. This approach synthesizes two techniques: protograph LDPC codes and OFDM. One symbol of encoded information by protograph LDPC codes corresponds to one sub-carrier, namely the length of encoded information equals to the number of sub-carriers. The design of good protograph LDPC codes with short lengths is given, and the proposed proto- graph LDPC codes can be of fast encoding, which can reduce the encoding complexity and simplify encoder hardware implementa- tion. The proposed approach provides a higher coding gain in the Rayleigh fading channel. The simulation results in the Rayleigh fading channel show that the bit error rate (BER) performance of the proposed time-frequency codes is as good as random LDPC- OFDM codes and is better than Tanner LDPC-OFDM codes under the condition of different fading coefficients.展开更多
As the 2nd generation digital terrestrial television broadcasting(DTTB)standard,digital terrestrial/television multimedia broadcasting-advanced(DTMB-A)can provide higher spectrum efficiency and transmission reliabilit...As the 2nd generation digital terrestrial television broadcasting(DTTB)standard,digital terrestrial/television multimedia broadcasting-advanced(DTMB-A)can provide higher spectrum efficiency and transmission reliability by adopting flexible frame structure and advanced forward error correction coding compared with the 1 st generation DTTB systems.In order to increase the flexibility and robustness of the DTTB network,the frequency reuse scheme of factor one(reuse-1)is proposed,where the same RF channel is used by different stations covering the adjacent service areas.However,it demands a very low carrier-tonoise ratio(C/N)threshold below 0 dB at the DTTB physical layer.In this paper,a robust broadcasting technique is proposed based on DTMB-A with newly designed low-rate low density parity check(LDPC)codes.By adopting quasi-cyclic(QC)Raptor-like structure and progressive lifting method,the high performance low-rate LDPC codes are designed supporting multiple code lengths.Both density-evolution analyses and laboratory measurements demonstrate that DTMB-A with low-rate coding can complete the demodulation reliably with the C/N threshold below0 d B,which is one important necessary condition to support frequency reuse-1 scheme.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
As an effective error correction technology,the Low Density Parity Check Code(LDPC)has been researched and applied by many scholars.Meanwhile,LDPC codes have some prominent performances,which involves close to the Sha...As an effective error correction technology,the Low Density Parity Check Code(LDPC)has been researched and applied by many scholars.Meanwhile,LDPC codes have some prominent performances,which involves close to the Shannon limit,achieving a higher bit rate and a fast decoding.However,whether these excellent characteristics are suitable for the resource-constrained Wireless Sensor Network(WSN),it seems to be seldom concerned.In this article,we review the LDPC code’s structure brief.ly,and them classify and summarize the LDPC codes’construction and decoding algorithms,finally,analyze the applications of LDPC code for WSN.We believe that our contributions will be able to facilitate the application of LDPC code in WSN.展开更多
This paper proposes the Low Density Parity Check (LDPC) coded Filtered MultiTone (FMT) systems with high-order modulation for the high data rate reliable transmission over frequency selective fading channel. For the p...This paper proposes the Low Density Parity Check (LDPC) coded Filtered MultiTone (FMT) systems with high-order modulation for the high data rate reliable transmission over frequency selective fading channel. For the purpose of accomplishing soft input soft output iterative decoding of LDPC codes, a new soft decision metric generation method is proposed,which obviates the need of the noise variance estimation, for M-PSK/M-QAM-type high-order modulation over frequency selective fading channel. Computer simulation indicates that, there is no performance loss with our new metric, but the complexity of implementation is reduced, and that the LDPC codes are effective to improve the Bit Error Rate (BER) of FMT in frequency selective fading channel.展开更多
An enhanced scheme is proposed for high code rate low density parity check (LDPC) coded partial incremental redundancy (PIR) hybrid automatic repeat request (HARQ). It employs the unequal error protection (UEP...An enhanced scheme is proposed for high code rate low density parity check (LDPC) coded partial incremental redundancy (PIR) hybrid automatic repeat request (HARQ). It employs the unequal error protection (UEP) technique for incremental redundancy bits and uses the constellation rearrangement (CoRe) technique for information bits in retransmissions so as to reduce the reliability variances of all encoded bits after soft combining. Simulation results show that the proposed scheme applies to both regular LDPC and irregular LDPC cases and can efficiently improve frame error rate (FER) performance and throughput performance.展开更多
The dual-containing (or self-orthogonal) formalism of Calderbank-Shor-Steane (CSS) codes provides a universal connection between a classical linear code and a Quantum Error-Correcting Code (QECC). We propose a novel c...The dual-containing (or self-orthogonal) formalism of Calderbank-Shor-Steane (CSS) codes provides a universal connection between a classical linear code and a Quantum Error-Correcting Code (QECC). We propose a novel class of quantum Low Density Parity Check (LDPC) codes constructed from cyclic classes of lines in Euclidean Geometry (EG). The corresponding constructed parity check matrix has quasi-cyclic structure that can be encoded flexibility, and satisfies the requirement of dual-containing quantum code. Taking the advantage of quasi-cyclic structure, we use a structured approach to construct Generalized Parity Check Matrix (GPCM). This new class of quantum codes has higher code rate, more sparse check matrix, and exactly one four-cycle in each pair of two rows. Ex-perimental results show that the proposed quantum codes, such as EG(2,q)II-QECC, EG(3,q)II-QECC, have better performance than that of other methods based on EG, over the depolarizing channel and decoded with iterative decoding based on the sum-product decoding algorithm.展开更多
The demodulation and decoding solution commonly used in the bit interleaving code modulation and the LDPC coded demodulation and decoding system of the iterative decoding (BICM-ID) is to report the soft information ...The demodulation and decoding solution commonly used in the bit interleaving code modulation and the LDPC coded demodulation and decoding system of the iterative decoding (BICM-ID) is to report the soft information output from the decoder of the receiver to the demodulator as priori information for completing the decoding. However, this will give rise to the reduction of the minimum Euclidean distances between codes, so that the performances of the system decline under non-fading Gaussian channel. According to this problem, an optimized iterative demodulation decoding solution is proposed and also is analyzed using simulation. The result shows that this solution can improve the demodulation and decoding performances of LDPC coded modulation and demodulation system.展开更多
This letter gives a random construction for Low Density Parity Check (LDPC) codes, which uses an iterative algorithm to avoid short cycles in the Tanner graph. The construction method has great flexible choice in LDPC...This letter gives a random construction for Low Density Parity Check (LDPC) codes, which uses an iterative algorithm to avoid short cycles in the Tanner graph. The construction method has great flexible choice in LDPC code's parameters including codelength, code rate, the least girth of the graph, the weight of column and row in the parity check matrix. The method can be applied to the irregular LDPC codes and strict regular LDPC codes. Systemic codes have many applications in digital communication, so this letter proposes a construction of the generator matrix of systemic LDPC codes from the parity check matrix. Simulations show that the method performs well with iterative decoding.展开更多
Reliability-based hybrid automatic repeat request (HARQ) (RB-HARQ) is a recently developed form of incremental-redundancy ARQ. It achieves good performance whereas large retransmission request packets should be fe...Reliability-based hybrid automatic repeat request (HARQ) (RB-HARQ) is a recently developed form of incremental-redundancy ARQ. It achieves good performance whereas large retransmission request packets should be fed back. In this paper, in order to reduce the number of the fed back bits, we propose a HARQ scheme applied in time duplex division orthogonal frequency division multiplexing (TDD- OFI)M) system over the slow fading channel which is named channel-based HARQ (CB-HARQ). Because one bit which meets deep fading is always with small value of log likelihood ratio (LLR) during the process of decoding of LDPC code, the bits transmitted on the carrier with deep fading are retransmitted. At the receiver, the decoder will compute the locations of retransmission bits according to the channel fading values which are gotten by utilizing the feature of channel symmetry in TDD mode. So the indices of retransmission bits are avoided to be transmitted. Simulation results show that this method achieves better BER performance and requires much smaller request packets in feedback link.展开更多
With the rapid growth of the offshore wind industry, the innovative floating offshore wind turbine is chosen as the most feasible device to harvest the vast wind energy in deep water area. However there is no practica...With the rapid growth of the offshore wind industry, the innovative floating offshore wind turbine is chosen as the most feasible device to harvest the vast wind energy in deep water area. However there is no practical design guide for the floating wind turbine especially the floating foundation. In this paper, based on the investigation on the worldwide floating wind turbine and current available expertise on floating platforms accumulated in offshore O/G (oil and gas) industry, an integrated design methodology is presented according to the specialized characteristics of wind turbine, including the type selection of foundation and mooring system, design standard, design procedure, design conditions, key technologies involved. Finally a semi-submersible floating foundation is designed to support certain megawatt-rating wind turbine of Goldwind and also performance analysis and code checks are performed to validate the design. The design method of the floating foundation provided in this paper is proved feasible and can be adopted in practical engineering design.展开更多
The distribution law of the random code structure of randomly constructed irregular low-density parity-check (LDPC) codes is studied, Based on the Progressive Edge-Growth (PEG) algorithm, a new algorithm which can...The distribution law of the random code structure of randomly constructed irregular low-density parity-check (LDPC) codes is studied, Based on the Progressive Edge-Growth (PEG) algorithm, a new algorithm which can both ellminate short cycles and keep the distribution of the random code structure is presented, The experimentsl results show that the performance of the irregular LDPC codes constructed by the new algorithm is superior to that of the PEG algorithm,展开更多
The well-known CCSDS(consultative committee for space data systems) LDPC(low density parity check) code for near-earth applications is discussed and used for a case study of Mc Eliece system. First, a data error is pi...The well-known CCSDS(consultative committee for space data systems) LDPC(low density parity check) code for near-earth applications is discussed and used for a case study of Mc Eliece system. First, a data error is picked out with the CCSDS LDPC code. The problem with its generator matrix is illustrated and overcome by a shortened code with some middle code bits deleted. In correspondence, its parity check matrix is also revised with the new quasi-cyclic(QC)-LDPC code. Second, a fast decoding scheme for general QC-LDPC codes is proposed based on flipping bits and fetching words. Besides, a lightweight CCSDS LDPC code based Mc Eliece system can be set up with such codes. The repaired CCSDS LDPC code is supposed to be still useful for communications and storages, and the normalized decoding algorithm is also efficient for general QC-LDPC codes.展开更多
This paper describes an efficient implementation of the Sum-Product Algorithm (SPA) within a Low Density Parity Check (LDPC) code decoder, where a horizontal process correction term is used to improve the decoclin...This paper describes an efficient implementation of the Sum-Product Algorithm (SPA) within a Low Density Parity Check (LDPC) code decoder, where a horizontal process correction term is used to improve the decocling performance of the Min-Sum algorithms. The correction term is implemented as a look-up table. The algorithm uses the correction term redundancy by means of a coordinate transformation to reduce the hardware complexity. Simulations and hardware tests indicate that the decoding performance is very good with the appropriate look-up table展开更多
By constructing an accumulated-crossover relationship in multiple parallel concatenated single parity check (M-PC-SPC) codes, a class of error-correcting codes, termed multiple accumulated-crossover parallel concate...By constructing an accumulated-crossover relationship in multiple parallel concatenated single parity check (M-PC-SPC) codes, a class of error-correcting codes, termed multiple accumulated-crossover parallel concatenated single parity check (M-ACPC-SPC) codes, is proposed. M-ACPC-SPC codes possess linear encoding complexity and can be decoded iteratively with low complexity by the sum-product algorithm (SPA). Simulation results show that M-ACPC-SPC codes have lower error floors than M-PCSPC codes with the same dimension, and when the dimension is 5, M-ACPC-SPC codes achieve bit error rate (BER) better than (3, 6) regular low density parity check (LDPC) codes.展开更多
Area-efficient design methodology is proposed for the analog decoding implementations of the rate-l/2 accumulate repeat-4 jagged-accumulate (AR4JA) low density parity check (LDPC) code. The proposed approach is de...Area-efficient design methodology is proposed for the analog decoding implementations of the rate-l/2 accumulate repeat-4 jagged-accumulate (AR4JA) low density parity check (LDPC) code. The proposed approach is designed using optimized decoding architecture and regularized routing network, in such a way that the overall wiring overhead is minimized and the silicon area utilization is significantly improved. The prototyping chip used to verily the approach is tully integrated in a four-metal double-poly 0.35 lam complementary metal oxide semiconductor (CMOS) technology, and includes an input-output interface that maximizes the decoder throughput. The decoding core area is 2.02 mm2 with a post-layout area utilization of 80%. The decoder was successfully tested at the maximum data rate of 10 Mbit/s, with a core power consumption of 6.78 mW at 3.3 V, which corresponds to an energy per decoded bit of 0.677 nJ. The proposed analog LDPC decoder with low processing power and high-reliability is suitable lbr space- and power-constrained spacecraft system.展开更多
基金Project supported by the National Key Basic Research Program of China(Grant No.2014CB339803)the National High Technology Research and Development Program of China(Grant No.2011AA010205)+4 种基金the National Natural Science Foundation of China(Grant Nos.61131006,61321492,and 61204135)the Major National Development Project of Scientific Instrument and Equipment(Grant No.2011YQ150021)the National Science and Technology Major Project(Grant No.2011ZX02707)the International Collaboration and Innovation Program on High Mobility Materials Engineering of the Chinese Academy of Sciencesthe Shanghai Municipal Commission of Science and Technology(Grant No.14530711300)
文摘Atmospheric absorption, scattering, and scintillation are the major causes to deteriorate the transmission quality of terahertz(THz) wireless communications. An error control coding scheme based on low density parity check(LDPC) codes with soft decision decoding algorithm is proposed to improve the bit-error-rate(BER) performance of an on-off keying(OOK) modulated THz signal through atmospheric channel. The THz wave propagation characteristics and channel model in atmosphere is set up. Numerical simulations validate the great performance of LDPC codes against the atmospheric fading and demonstrate the huge potential in future ultra-high speed beyond Gbps THz communications.
基金supported by Beijing Natural Science Foundation(4102050)the National Natural Science of Foundation of China(NSFC)-Korea Science and Engineering Foundation (KOSF) Joint Research Project of China and Korea (60811140343)
文摘The application of protograph low density parity check (LDPC) codes involves the encoding complexity problem. Since the generator matrices are dense, and if the positions of "1" s are irregularity, the encoder needs to store every "1" of the generator matrices by using huge chip area. In order to solve this problem, we need to design the protograph LDPC codes with circular generator matrices. A theorem concerning the circulating property of generator matrices of nonsingular protograph LDPC codes is proposed. The circulating property of generator matrix of nonsingular protograph LDPC codes can be obtained from the corresponding quasi-cyclic parity check matrix. This paper gives a scheme of constructing protograph LDPC codes with circulating generator matrices, and it reveals that the fast encoding algorithm of protograph LDPC codes has lower encoding complexity under the condition of the proposed theorem. Simulation results in ad- ditive white Gaussian noise (AWGN) channels show that the bit error rate (BER) performance of the designed codes based on the proposed theorem is much better than that of GB20600 LDPC codes and Tanner LDPC codes.
基金National Natural Science Foundation of China(No.61272432)Qingdao Science and Technology Development Plan(No.12-1-4-6-(10)-jch)
文摘Watermarking system based on quantization index modulation (QIM) is increasingly popular in high payload applications,but it is inherently fragile against amplitude scaling attacks.In order to resist desynchronization attacks of QIM digital watermarking,a low density parity check (LDPC) code-aided QIM watermarking algorithm is proposed,and the performance of QIM watermarking system can be improved by incorporating LDPC code with message passing estimation/detection framework.Using the theory of iterative estimation and decoding,the watermark signal is decoded by the proposed algorithm through iterative estimation of amplitude scaling parameters and decoding of watermark.The performance of the proposed algorithm is closer to the dirty paper Shannon limit than that of repetition code aided algorithm when the algorithm is attacked by the additive white Gaussian noise.For constant amplitude scaling attacks,the proposed algorithm can obtain the accurate estimation of amplitude scaling parameters.The simulation result shows that the algorithm can obtain similar performance compared to the algorithm without desynchronization.
文摘In this paper, we present a Joint Source-Channel Decoding algorithm (JSCD) for Low-Density Parity Check (LDPC) codes by modifying the Sum-Product Algorithm (SPA) to account for the source redun-dancy, which results from the neighbouring Huffman coded bits. Simulations demonstrate that in the presence of source redundancy, the proposed algorithm gives better performance than the Separate Source and Channel Decoding algorithm (SSCD).
基金supported by the Beijing Natural Science Foundation of China (4102050)the National Natural Science of Foundation of China (NSFC)-Korea Science and Engineering Foundation (KOSF) Joint Research Project of China and Korea (60811140343)
文摘This paper proposes a scheme to construct time- frequency codes based on protograph low density parity check (LDPC) codes in orthogonal frequency division multiplexing (OFDM) communication systems. This approach synthesizes two techniques: protograph LDPC codes and OFDM. One symbol of encoded information by protograph LDPC codes corresponds to one sub-carrier, namely the length of encoded information equals to the number of sub-carriers. The design of good protograph LDPC codes with short lengths is given, and the proposed proto- graph LDPC codes can be of fast encoding, which can reduce the encoding complexity and simplify encoder hardware implementa- tion. The proposed approach provides a higher coding gain in the Rayleigh fading channel. The simulation results in the Rayleigh fading channel show that the bit error rate (BER) performance of the proposed time-frequency codes is as good as random LDPC- OFDM codes and is better than Tanner LDPC-OFDM codes under the condition of different fading coefficients.
基金supported in part by the National Natural Science Foundation of China(NSFC)under Grant 61931015the Peng Cheng Laboratory under Grant PCL2021A10+1 种基金the Science,Technology and Innovation Commission of Shenzhen Municipality(No.JSGG20201103095805015)sponsored by Tsinghua University-Yunnan Mobile Digital TV Company Ltd.,Joint Research Center(JCICBN)。
文摘As the 2nd generation digital terrestrial television broadcasting(DTTB)standard,digital terrestrial/television multimedia broadcasting-advanced(DTMB-A)can provide higher spectrum efficiency and transmission reliability by adopting flexible frame structure and advanced forward error correction coding compared with the 1 st generation DTTB systems.In order to increase the flexibility and robustness of the DTTB network,the frequency reuse scheme of factor one(reuse-1)is proposed,where the same RF channel is used by different stations covering the adjacent service areas.However,it demands a very low carrier-tonoise ratio(C/N)threshold below 0 dB at the DTTB physical layer.In this paper,a robust broadcasting technique is proposed based on DTMB-A with newly designed low-rate low density parity check(LDPC)codes.By adopting quasi-cyclic(QC)Raptor-like structure and progressive lifting method,the high performance low-rate LDPC codes are designed supporting multiple code lengths.Both density-evolution analyses and laboratory measurements demonstrate that DTMB-A with low-rate coding can complete the demodulation reliably with the C/N threshold below0 d B,which is one important necessary condition to support frequency reuse-1 scheme.
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.
基金This work is partially supported by the National Natural Science Foundation of China(No.61571004)the Shanghai Natural Science Foundation(No.17ZR1429100)+2 种基金the Science and Technology Innovation Program of Shanghai(No.115DZ1100400)Fujian Science and Technology Plan STS Program(2017T3009)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(No.YJKYYQ20170074).
文摘As an effective error correction technology,the Low Density Parity Check Code(LDPC)has been researched and applied by many scholars.Meanwhile,LDPC codes have some prominent performances,which involves close to the Shannon limit,achieving a higher bit rate and a fast decoding.However,whether these excellent characteristics are suitable for the resource-constrained Wireless Sensor Network(WSN),it seems to be seldom concerned.In this article,we review the LDPC code’s structure brief.ly,and them classify and summarize the LDPC codes’construction and decoding algorithms,finally,analyze the applications of LDPC code for WSN.We believe that our contributions will be able to facilitate the application of LDPC code in WSN.
基金Supported by 863 program of China under Grant 2001AA123015.
文摘This paper proposes the Low Density Parity Check (LDPC) coded Filtered MultiTone (FMT) systems with high-order modulation for the high data rate reliable transmission over frequency selective fading channel. For the purpose of accomplishing soft input soft output iterative decoding of LDPC codes, a new soft decision metric generation method is proposed,which obviates the need of the noise variance estimation, for M-PSK/M-QAM-type high-order modulation over frequency selective fading channel. Computer simulation indicates that, there is no performance loss with our new metric, but the complexity of implementation is reduced, and that the LDPC codes are effective to improve the Bit Error Rate (BER) of FMT in frequency selective fading channel.
基金Sponsored by the National Natural Science Foundation of China(60502026)
文摘An enhanced scheme is proposed for high code rate low density parity check (LDPC) coded partial incremental redundancy (PIR) hybrid automatic repeat request (HARQ). It employs the unequal error protection (UEP) technique for incremental redundancy bits and uses the constellation rearrangement (CoRe) technique for information bits in retransmissions so as to reduce the reliability variances of all encoded bits after soft combining. Simulation results show that the proposed scheme applies to both regular LDPC and irregular LDPC cases and can efficiently improve frame error rate (FER) performance and throughput performance.
基金Supported by the National Natural Science Foundation ofChina (No. 61071145,41074090)the Specialized Research Fund for the Doctoral Program of Higher Education (200802880014)
文摘The dual-containing (or self-orthogonal) formalism of Calderbank-Shor-Steane (CSS) codes provides a universal connection between a classical linear code and a Quantum Error-Correcting Code (QECC). We propose a novel class of quantum Low Density Parity Check (LDPC) codes constructed from cyclic classes of lines in Euclidean Geometry (EG). The corresponding constructed parity check matrix has quasi-cyclic structure that can be encoded flexibility, and satisfies the requirement of dual-containing quantum code. Taking the advantage of quasi-cyclic structure, we use a structured approach to construct Generalized Parity Check Matrix (GPCM). This new class of quantum codes has higher code rate, more sparse check matrix, and exactly one four-cycle in each pair of two rows. Ex-perimental results show that the proposed quantum codes, such as EG(2,q)II-QECC, EG(3,q)II-QECC, have better performance than that of other methods based on EG, over the depolarizing channel and decoded with iterative decoding based on the sum-product decoding algorithm.
文摘The demodulation and decoding solution commonly used in the bit interleaving code modulation and the LDPC coded demodulation and decoding system of the iterative decoding (BICM-ID) is to report the soft information output from the decoder of the receiver to the demodulator as priori information for completing the decoding. However, this will give rise to the reduction of the minimum Euclidean distances between codes, so that the performances of the system decline under non-fading Gaussian channel. According to this problem, an optimized iterative demodulation decoding solution is proposed and also is analyzed using simulation. The result shows that this solution can improve the demodulation and decoding performances of LDPC coded modulation and demodulation system.
基金Supported by the National Natural Science Foundation of China(No.60472053)
文摘This letter gives a random construction for Low Density Parity Check (LDPC) codes, which uses an iterative algorithm to avoid short cycles in the Tanner graph. The construction method has great flexible choice in LDPC code's parameters including codelength, code rate, the least girth of the graph, the weight of column and row in the parity check matrix. The method can be applied to the irregular LDPC codes and strict regular LDPC codes. Systemic codes have many applications in digital communication, so this letter proposes a construction of the generator matrix of systemic LDPC codes from the parity check matrix. Simulations show that the method performs well with iterative decoding.
基金the National High Technology Research and Development Programme of China(No.2003AA12331004)
文摘Reliability-based hybrid automatic repeat request (HARQ) (RB-HARQ) is a recently developed form of incremental-redundancy ARQ. It achieves good performance whereas large retransmission request packets should be fed back. In this paper, in order to reduce the number of the fed back bits, we propose a HARQ scheme applied in time duplex division orthogonal frequency division multiplexing (TDD- OFI)M) system over the slow fading channel which is named channel-based HARQ (CB-HARQ). Because one bit which meets deep fading is always with small value of log likelihood ratio (LLR) during the process of decoding of LDPC code, the bits transmitted on the carrier with deep fading are retransmitted. At the receiver, the decoder will compute the locations of retransmission bits according to the channel fading values which are gotten by utilizing the feature of channel symmetry in TDD mode. So the indices of retransmission bits are avoided to be transmitted. Simulation results show that this method achieves better BER performance and requires much smaller request packets in feedback link.
文摘With the rapid growth of the offshore wind industry, the innovative floating offshore wind turbine is chosen as the most feasible device to harvest the vast wind energy in deep water area. However there is no practical design guide for the floating wind turbine especially the floating foundation. In this paper, based on the investigation on the worldwide floating wind turbine and current available expertise on floating platforms accumulated in offshore O/G (oil and gas) industry, an integrated design methodology is presented according to the specialized characteristics of wind turbine, including the type selection of foundation and mooring system, design standard, design procedure, design conditions, key technologies involved. Finally a semi-submersible floating foundation is designed to support certain megawatt-rating wind turbine of Goldwind and also performance analysis and code checks are performed to validate the design. The design method of the floating foundation provided in this paper is proved feasible and can be adopted in practical engineering design.
基金Supported by the National Natural Science Foundation of China (Grant No. 60172030)Huawei Science FoundationXidian ISN National Key Laboratory
文摘The distribution law of the random code structure of randomly constructed irregular low-density parity-check (LDPC) codes is studied, Based on the Progressive Edge-Growth (PEG) algorithm, a new algorithm which can both ellminate short cycles and keep the distribution of the random code structure is presented, The experimentsl results show that the performance of the irregular LDPC codes constructed by the new algorithm is superior to that of the PEG algorithm,
基金Supported by the Guangzhou Innovation Leading Team Program (201909010008)。
文摘The well-known CCSDS(consultative committee for space data systems) LDPC(low density parity check) code for near-earth applications is discussed and used for a case study of Mc Eliece system. First, a data error is picked out with the CCSDS LDPC code. The problem with its generator matrix is illustrated and overcome by a shortened code with some middle code bits deleted. In correspondence, its parity check matrix is also revised with the new quasi-cyclic(QC)-LDPC code. Second, a fast decoding scheme for general QC-LDPC codes is proposed based on flipping bits and fetching words. Besides, a lightweight CCSDS LDPC code based Mc Eliece system can be set up with such codes. The repaired CCSDS LDPC code is supposed to be still useful for communications and storages, and the normalized decoding algorithm is also efficient for general QC-LDPC codes.
基金supported by Tsinghua University Initiative Scientific Research Program(No.2010THZ0)the National Key Basic Research (973) Program of China(No.2012CB316000)
文摘This paper describes an efficient implementation of the Sum-Product Algorithm (SPA) within a Low Density Parity Check (LDPC) code decoder, where a horizontal process correction term is used to improve the decocling performance of the Min-Sum algorithms. The correction term is implemented as a look-up table. The algorithm uses the correction term redundancy by means of a coordinate transformation to reduce the hardware complexity. Simulations and hardware tests indicate that the decoding performance is very good with the appropriate look-up table
基金Supported by the National High-Tech Research & Development Program of China (Grant No. 2007AA01Z288)the National Science Fund for Distinguished Young Scholars (Grant No. 60725105)the Program for Changjiang Scholars and Innovative Research Team in University and the 111 Project (Grant No. B08038)
文摘By constructing an accumulated-crossover relationship in multiple parallel concatenated single parity check (M-PC-SPC) codes, a class of error-correcting codes, termed multiple accumulated-crossover parallel concatenated single parity check (M-ACPC-SPC) codes, is proposed. M-ACPC-SPC codes possess linear encoding complexity and can be decoded iteratively with low complexity by the sum-product algorithm (SPA). Simulation results show that M-ACPC-SPC codes have lower error floors than M-PCSPC codes with the same dimension, and when the dimension is 5, M-ACPC-SPC codes achieve bit error rate (BER) better than (3, 6) regular low density parity check (LDPC) codes.
文摘Area-efficient design methodology is proposed for the analog decoding implementations of the rate-l/2 accumulate repeat-4 jagged-accumulate (AR4JA) low density parity check (LDPC) code. The proposed approach is designed using optimized decoding architecture and regularized routing network, in such a way that the overall wiring overhead is minimized and the silicon area utilization is significantly improved. The prototyping chip used to verily the approach is tully integrated in a four-metal double-poly 0.35 lam complementary metal oxide semiconductor (CMOS) technology, and includes an input-output interface that maximizes the decoder throughput. The decoding core area is 2.02 mm2 with a post-layout area utilization of 80%. The decoder was successfully tested at the maximum data rate of 10 Mbit/s, with a core power consumption of 6.78 mW at 3.3 V, which corresponds to an energy per decoded bit of 0.677 nJ. The proposed analog LDPC decoder with low processing power and high-reliability is suitable lbr space- and power-constrained spacecraft system.