This paper introduces a hybrid fluid-kinetic code,SHYPIC(ShanghaiTech HYbrid PIC code),developed as a baseline framework for simulating plasma dynamics relevant to plasma-jetdriven magneto-inertial fusion(PJMIF).The c...This paper introduces a hybrid fluid-kinetic code,SHYPIC(ShanghaiTech HYbrid PIC code),developed as a baseline framework for simulating plasma dynamics relevant to plasma-jetdriven magneto-inertial fusion(PJMIF).The code integrates a fluid description for electrons and a particle-in-cell(PIC)description for ions,providing computational efficiency and enabling larger-scale simulations.It incorporates ion kinetic effects,allowing accurate simulation of microscale non-equilibrium phenomena.In this initial version,the SHYPIC code is presented along with a series of benchmark tests,including quiet plasma evolution,dispersion relation verification,and the excitation and propagation of externally driven plasma waves.This version does not yet incorporate collisional effects or non-ideal terms(e.g.,resistivity,viscosity,and hyperviscosity)in the electron fluid,which will be included in future developments.The present work lays the foundation for further improvements required for fully simulating the complex dynamics of PJMIF.展开更多
Presents the fuzzy neural network optimized by hybrid coded genetic algorithm of decimal encoding and binary encoding, the searching ability and stability of genetic algorithms enhanced by using binary encoding during...Presents the fuzzy neural network optimized by hybrid coded genetic algorithm of decimal encoding and binary encoding, the searching ability and stability of genetic algorithms enhanced by using binary encoding during the crossover operation and decimal encoding during the mutation operation, and the way of accepting new individuals by probability adopted, by which a new individual is accepted and its parent is discarded when its fitness is higher than that of its parent, and a new individual is accepted by probability when its fitness is lower than that of its parent. And concludes with calculations made with an example that these improvements enhance the speed of genetic algorithms to optimize the fuzzy neural network controller.展开更多
In this paper,we develop a novel hybrid automatic-repeat-request(ARQ)protocol for the quantum communication system using quantum stabilizer codes.The quantum information is encoded by stabilizer codes to against the c...In this paper,we develop a novel hybrid automatic-repeat-request(ARQ)protocol for the quantum communication system using quantum stabilizer codes.The quantum information is encoded by stabilizer codes to against the channel noise.The twophoton entangled state is prepared for codeword secure transmission.Hybrid ARQ protocol rules the recognition and retransmission of error codewords.In this protocol,the property of quantum entangled state ensures the security of information,the theory of hybrid ARQ system improves the reliability of transmission,the theory of quantum stabilizer codes corrects the flipping errors of codewords.Finally,we verify the security and throughput efficiency of this protocol.展开更多
A dual N-ary orthogonal hybrid modulation system is introduced in this paper, which can increase the data rate greatly compared with conventional N-ary orthogonal spread spectrum system, so it can be used for high rat...A dual N-ary orthogonal hybrid modulation system is introduced in this paper, which can increase the data rate greatly compared with conventional N-ary orthogonal spread spectrum system, so it can be used for high rate data communication. Then, three code recognition algorithms are presented for dual N-ary orthogonal hybrid modulation system and the analytic bit error rate （BER） performance of the system in additive white Gaussian noise （AWGN） and fiat Rayleigh fading channel is derived. Finally, the computer simulation of the system with three code recognition algorithms is performed, which shows that the simplified maximum a posteriori （MAP） algorithm is the best for the system with a compromise between the performance and the complexity.展开更多
A hybrid decoding algorithm is proposed for nonbinary low-density parity-check （LDPC） codes, which combines the weighted symbol-flipping （WSF） algorithm with the fast Fourier trans- form q-ary sum-product algorit...A hybrid decoding algorithm is proposed for nonbinary low-density parity-check （LDPC） codes, which combines the weighted symbol-flipping （WSF） algorithm with the fast Fourier trans- form q-ary sum-product algorithm （FFT-QSPA）. The flipped position and value are determined by the symbol flipping metric and the received bit values in the first stage WSF algorithm. If the low- eomplexity WSF algorithm is failed, the second stage FFT-QSPA is activated as a switching strategy. Simulation results show that the proposed hybrid algorithm greatly reduces the computational complexity with the performance close to that of FFT-QSPA.展开更多
An in-memory storage system provides submillisecond latency and improves the concurrency of user applications by caching data into memory from external storage.Fault tolerance of in-memory storage systems is essential...An in-memory storage system provides submillisecond latency and improves the concurrency of user applications by caching data into memory from external storage.Fault tolerance of in-memory storage systems is essential,as the loss of cached data requires access to data from external storage,which evidently increases the response latency.Typically,replication and erasure code(EC)are two fault-tolerant schemes that pose different trade-offs between access performance and storage usage.To help make the best performance and space trade-off,we design ElasticMem,a hybrid fault-tolerant distributed in-memory storage system that supports elastic redundancy transition to dynamically change the fault-tolerant scheme.ElasticMem exploits a novel EC-oriented replication(EOR)that carefully designs the data placement of replication according to the future data layout of EC to enhance the I/O efficiency of redundancy transition.ElasticMem solves the consistency problem caused by concurrent data accesses via a lightweight table-based scheme combined with data bypassing.It detects correlated read and write requests and serves subsequent read requests with local data.We implement a prototype that realizes ElasticMem based on Memcached.Experiments show that ElasticMem remarkably reduces the time of redundancy transition,the overall latency of correlated concurrent data accesses,and the latency of single data access among them.展开更多
An incremental redundancy hybrid automatic repeat- request （IR-HARQ）scheme based on irregular repeat-accumulate （IRA）codes is proposed. The design of rate compatible punctured IRA codes suitable for an IR-HARQ sch...An incremental redundancy hybrid automatic repeat- request （IR-HARQ）scheme based on irregular repeat-accumulate （IRA）codes is proposed. The design of rate compatible punctured IRA codes suitable for an IR-HARQ scheme is well formulated and efficiently solved by a linear-programming method, along with a one-dimensional approach for density evolution. Compared to IR-HARQ schemes based on turbo codes, simulation shows that the proposed IR-HARQ schemes based on IRA codes may achieve almost the same performance at a block size of 1 024, but better throughput at a block size of 4 096. The advantages of the proposed scheme in implementation, including decoding complexity and parallelism, make it more attractive in practice than the IR-HARQ schemes based on both turbo and LDPC codes.展开更多
This paper presents a new test data compression/decompression method for SoC testing,called hybrid run length codes. The method makes a full analysis of the factors which influence test parameters：compression ratio,t...This paper presents a new test data compression/decompression method for SoC testing,called hybrid run length codes. The method makes a full analysis of the factors which influence test parameters：compression ratio,test application time, and area overhead. To improve the compression ratio, the new method is based on variable-to-variable run length codes,and a novel algorithm is proposed to reorder the test vectors and fill the unspecified bits in the pre-processing step. With a novel on-chip decoder, low test application time and low area overhead are obtained by hybrid run length codes. Finally, an experimental comparison on ISCAS 89 benchmark circuits validates the proposed method展开更多
Although the wireless network is widely used in many fields,its characteristics such as high bit error rate and broadcast links may block its development.Network coding is an artistic way to exploit its intrinsic char...Although the wireless network is widely used in many fields,its characteristics such as high bit error rate and broadcast links may block its development.Network coding is an artistic way to exploit its intrinsic characteristics to increase the network reliability.Some people research network coding schemes for inter-flow or intra-flow,each type with its own advantages and disadvantages.In this paper,we propose a new mechanism,called MM-NCOPE,which integrates the idea of inter-flow and intra-flow coding.On the one hand,MM-NCOPE utilizes random liner coding to encode the NCOPE packets while NCOPE is a sub-protocol for optimizing the COPE algorithm by iteration.In NCOPE,packets are automatically matched by size to be coded.As a result,it improves the coding gain in some level.On the other hand,we adopt the partial Acknowledgement retransmission scheme to achieve high compactness and robustness.ACK is an independent packet with the highest priority rather than a part of the data packets.Compared with existing works on opportunistic network coding,our approach ensures the reliability of wireless links and improves the coding gain.展开更多
In order to exploit the evolution and find novel low-molecular-weight glutenin subunit （LMW-GS） for improvement of common wheat quality, thirteen variants from a somatic hybrid introgression line II-12 between Triti...In order to exploit the evolution and find novel low-molecular-weight glutenin subunit （LMW-GS） for improvement of common wheat quality, thirteen variants from a somatic hybrid introgression line II-12 between Triticum aestivum cv. Jinan 177 （JN177） and Agropyron elongatum were characterized via genomic PCR. Four clones were pseudogenes because they contained an internal stop codon. The remaining nine variants contained intact open reading frames （ORFs）. Sequence alignment indicates that the proteins deduced from the nine ORFs have similar primary structure with LMW-GS cloned from its parents previously. However, they have some unique modifications in the structures. For example, EU292737 contains not only an extra Cys residue in the C-terminal domain but also a long repetitive domain. Both EU 159511 and EU292738 start their first Cys residue in the N-terminal repetitive domain, but not in the N-conserved domain traditionally. These structural alterations may have positive contributions to wheat flour quality. The results of phylogeny showed that most LMW-GS variances from 11-12 were homologous to those from parent JN177 and other wheat lines. The reason for quick evolution of LMW-GS in 11-12 was discussed.展开更多
Fountain codes are considered to be a promising coding technique in underwater acoustic communication（UAC） which is challenged with the unique propagation features of the underwater acoustic channel and the harsh ma...Fountain codes are considered to be a promising coding technique in underwater acoustic communication（UAC） which is challenged with the unique propagation features of the underwater acoustic channel and the harsh marine environment. And Luby transform（LT） codes are the first codes fully realizing the digital fountain concept. However, in conventional LT encoding/decoding algorithms, due to the imperfect coverage（IC） of input symbols and short cycles in the generator matrix, stopping sets would occur and terminate the decoding. Thus, the recovery probability is reduced,high coding overhead is required and decoding delay is increased.These issues would be disadvantages while applying LT codes in underwater acoustic communication. Aimed at solving those issues, novel encoding/decoding algorithms are proposed. First,a doping and non-uniform selecting（DNS） encoding algorithm is proposed to solve the IC and the generation of short cycles problems. And this can reduce the probability of stopping sets occur during decoding. Second, a hybrid on the fly Gaussian elimination and belief propagation（OFG-BP） decoding algorithm is designed to reduce the decoding delay and efficiently utilize the information of stopping sets. Comparisons via Monte Carlo simulation confirm that the proposed schemes could achieve better overall decoding performances in comparison with conventional schemes.展开更多
Both high-dense wireless connectivity and ultra-huge network capacity are main challenges of next generation broadband networks.As one of its key promising technologies,non-orthogonal multi-ple access(NOMA)scheme can ...Both high-dense wireless connectivity and ultra-huge network capacity are main challenges of next generation broadband networks.As one of its key promising technologies,non-orthogonal multi-ple access(NOMA)scheme can solve those challenges and meet those needs to some extent,in the way that different user equipments(UEs)multiplex on the same resource.Researchers around the world have presented numerous NOMA solutions.Among those,sparse code multiple access(SC-MA)technology is a typical NOMA solution.It supports scheduled access and random access which can be called granted access and grant-free access respectively.But resources allocated to granted UEs and grant-free UEs are strictly separated.In order to improve resource utilization,a hybrid non-orthogonal multiple access scheme is proposed.It allows granted UEs and grant-free UEs sharing the same resource unit in terms of fine-grained integration.On the basis,a resource allocation method is further brought forward based on genetic algorithm.It optimizes resource allocation of all UEs by mapping resource distribution issue to an optimization problem.Comparing throughputs of four meth-ods,simulation results demonstrate the proposed genetic algorithm has better throughput gain.展开更多
Based on the advantage of phase coded signal and stepped frequency signal,a new hybrid modulation signal is introduced in this paper. It combines phase code modulation during the pulse with stepped frequency modulatio...Based on the advantage of phase coded signal and stepped frequency signal,a new hybrid modulation signal is introduced in this paper. It combines phase code modulation during the pulse with stepped frequency modulation between the pulses, which is named as phase-coded stepped-frequency ( PCSF ) signal. By analyzing its waveform and ambiguity function,the comparison between Stepped-Frequency ( SF) signal and PCSF signal is given,which shows that the PCSF signal is better than SF signal. Finally,the signal processing method with two stage compressed processing is presented. The simulation results show that this new hybrid modulation radar signal can get a higher stepped frequency than ordinary SF signal,realize the same equivalent bandwidth with less pulse number,and solve the conflict among the stepped frequency,the number of pulse, and transmit average power. Under the premises of a certain range resolution,this new hybrid modulation radar signal not only raises the data rate of radar system,but also reduces Doppler sensitivity with a good prospect, and the effect of one-dimensional range profile is much better than that of traditional SF signal. Therefore,this new hybrid modulation radar signal can be widely used in application.展开更多
Hybrid direct sequence and slow frequency hopping spread spectrum multiple access systems (Hybrid DS/SFH SSMA) operating through nonselective slow Rayleigh fading channels was investigated. Multipath and Multiple acce...Hybrid direct sequence and slow frequency hopping spread spectrum multiple access systems (Hybrid DS/SFH SSMA) operating through nonselective slow Rayleigh fading channels was investigated. Multipath and Multiple access interference was taken into account. Expressions of the average error probability for the system were derived. Analytical and numerical results on the average probability of error were presented for the system examined. Random signature sequences and hopping patterns were employed for the system. The numerical results show the effects of the value of M for M ary frequency shift keying (MFSK) modulation and Reed Solomon (RS) coding on the system’s performance. The comparison between RS coded system and noncode system shows that error correction coding is essential to improve the system’s performance.展开更多
This paper extends the work on cross-layer design which combines adaptive modulation and coding at the physical layer and hybrid automatic repeat request protocol at the data link layer. By contrast with previous work...This paper extends the work on cross-layer design which combines adaptive modulation and coding at the physical layer and hybrid automatic repeat request protocol at the data link layer. By contrast with previous works on this topic, the present development and the performance analysis as well, is based on rate compatible punctured turbo codes. Rate compatibility provides incremental redundancy in transmission of parity bits for error correction at the data link layer. Turbo coding and iterative decoding gives lower packet error rate values in low signal-to-noise ratio regions of the adaptive modulation and coding (AMC) schemes. Thus, the applied cross-layer design results in AMC schemes can achieve better spectral efficiency than convolutional one while it retains the QoS requirements at the application layer. Numerical results in terms of spectral efficiency for both turbo and convolutional rate compatible punctured codes are presented. For a more comprehensive presentation, the performance of rate compatible LDPC is contrasted with turbo case as well as the performance complexity is discussed for each of the above codes.展开更多
In the recent era of software development,reusing software is one of the major activities that is widely used to save time.To reuse software,the copy and paste method is used and this whole process is known as code cl...In the recent era of software development,reusing software is one of the major activities that is widely used to save time.To reuse software,the copy and paste method is used and this whole process is known as code cloning.This activity leads to problems like difficulty in debugging,increase in time to debug and manage software code.In the literature,various algorithms have been developed to find out the clones but it takes too much time as well as more space to figure out the clones.Unfortunately,most of them are not scalable.This problem has been targeted upon in this paper.In the proposed framework,authors have proposed a new method of identifying clones that takes lesser time to find out clones as compared with many popular code clone detection algorithms.The proposed framework has also addressed one of the key issues in code clone detection i.e.,detection of near-miss(Type-3)and semantic clones(Type-4)with significant accuracy of 95.52%and 92.80%respectively.The present study is divided into two phases,the first method converts any code into an intermediate representation form i.e.,Hashinspired abstract syntax trees.In the second phase,these abstract syntax trees are passed to a novel approach“Similarity-based self-adjusting hash inspired abstract syntax tree”algorithm that helps in knowing the similarity level of codes.The proposed method has shown a lot of improvement over the existing code clones identification methods.展开更多
Low-Emissivity Hybrid Insulation has been developed in South Korea. It combines both resistive and reflective insulating principle. It is composed with many layers of reflective aluminum foils and honeycomb-structure ...Low-Emissivity Hybrid Insulation has been developed in South Korea. It combines both resistive and reflective insulating principle. It is composed with many layers of reflective aluminum foils and honeycomb-structure air cells with polyethylene foam. This paper introduces recent South Korean building insulation code and the applications of Low-Emissivity Hybrid Insulation to meet the code.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
The feasibility of the hybrid chaotic sequences as the spreading codes in code divided multiple access(CDMA) system is analyzed. The design and realization of the digital hybrid chaotic sequence generator by very high...The feasibility of the hybrid chaotic sequences as the spreading codes in code divided multiple access(CDMA) system is analyzed. The design and realization of the digital hybrid chaotic sequence generator by very high speed integrated circuit hardware description language(VHDL) are described. A valid hazard canceledl method is presented. Computer simulations show that the stable digital sequence waveforms can be produced. The correlations of the digital hybrid chaotic sequences are compared with those of m-sequences. The results show that the correlations of the digital hybrid chaotic sequences are almost as good as those of m-sequences. The works in this paper explored a road for the practical applications of chaos.展开更多
基金supported by the Major National Science and Technology Infrastructure(No.2208-000000-04-01249628)。
文摘This paper introduces a hybrid fluid-kinetic code,SHYPIC(ShanghaiTech HYbrid PIC code),developed as a baseline framework for simulating plasma dynamics relevant to plasma-jetdriven magneto-inertial fusion(PJMIF).The code integrates a fluid description for electrons and a particle-in-cell(PIC)description for ions,providing computational efficiency and enabling larger-scale simulations.It incorporates ion kinetic effects,allowing accurate simulation of microscale non-equilibrium phenomena.In this initial version,the SHYPIC code is presented along with a series of benchmark tests,including quiet plasma evolution,dispersion relation verification,and the excitation and propagation of externally driven plasma waves.This version does not yet incorporate collisional effects or non-ideal terms(e.g.,resistivity,viscosity,and hyperviscosity)in the electron fluid,which will be included in future developments.The present work lays the foundation for further improvements required for fully simulating the complex dynamics of PJMIF.
文摘Presents the fuzzy neural network optimized by hybrid coded genetic algorithm of decimal encoding and binary encoding, the searching ability and stability of genetic algorithms enhanced by using binary encoding during the crossover operation and decimal encoding during the mutation operation, and the way of accepting new individuals by probability adopted, by which a new individual is accepted and its parent is discarded when its fitness is higher than that of its parent, and a new individual is accepted by probability when its fitness is lower than that of its parent. And concludes with calculations made with an example that these improvements enhance the speed of genetic algorithms to optimize the fuzzy neural network controller.
基金The work is supported by was supported by the Shandong Province Higher Educational Science and Technology Program(Grant No.J18KZ012)the National Natural Science Foundation of China(Grant No.11975132,61772295)the Shandong Provincial Natural Science Foundation,China(Grant No.ZR2019YQ01).
文摘In this paper,we develop a novel hybrid automatic-repeat-request(ARQ)protocol for the quantum communication system using quantum stabilizer codes.The quantum information is encoded by stabilizer codes to against the channel noise.The twophoton entangled state is prepared for codeword secure transmission.Hybrid ARQ protocol rules the recognition and retransmission of error codewords.In this protocol,the property of quantum entangled state ensures the security of information,the theory of hybrid ARQ system improves the reliability of transmission,the theory of quantum stabilizer codes corrects the flipping errors of codewords.Finally,we verify the security and throughput efficiency of this protocol.
基金the National Basic Research Program of China(No5130601)Jiangsu Provincial Natural Science Foundation(NoBK2006701)
文摘A dual N-ary orthogonal hybrid modulation system is introduced in this paper, which can increase the data rate greatly compared with conventional N-ary orthogonal spread spectrum system, so it can be used for high rate data communication. Then, three code recognition algorithms are presented for dual N-ary orthogonal hybrid modulation system and the analytic bit error rate （BER） performance of the system in additive white Gaussian noise （AWGN） and fiat Rayleigh fading channel is derived. Finally, the computer simulation of the system with three code recognition algorithms is performed, which shows that the simplified maximum a posteriori （MAP） algorithm is the best for the system with a compromise between the performance and the complexity.
基金Supported by the National High Technology Research and Development Programme of China(No.2009AAJ128,2009AAJ208,2010AA7010422)
文摘A hybrid decoding algorithm is proposed for nonbinary low-density parity-check （LDPC） codes, which combines the weighted symbol-flipping （WSF） algorithm with the fast Fourier trans- form q-ary sum-product algorithm （FFT-QSPA）. The flipped position and value are determined by the symbol flipping metric and the received bit values in the first stage WSF algorithm. If the low- eomplexity WSF algorithm is failed, the second stage FFT-QSPA is activated as a switching strategy. Simulation results show that the proposed hybrid algorithm greatly reduces the computational complexity with the performance close to that of FFT-QSPA.
基金supported by the Fundamental Research Funds for the Central Universities(WK2150110022)Anhui Provincial Natural Science Foundation(2208085QF189)National Natural Science Foundation of China(62202440).
文摘An in-memory storage system provides submillisecond latency and improves the concurrency of user applications by caching data into memory from external storage.Fault tolerance of in-memory storage systems is essential,as the loss of cached data requires access to data from external storage,which evidently increases the response latency.Typically,replication and erasure code(EC)are two fault-tolerant schemes that pose different trade-offs between access performance and storage usage.To help make the best performance and space trade-off,we design ElasticMem,a hybrid fault-tolerant distributed in-memory storage system that supports elastic redundancy transition to dynamically change the fault-tolerant scheme.ElasticMem exploits a novel EC-oriented replication(EOR)that carefully designs the data placement of replication according to the future data layout of EC to enhance the I/O efficiency of redundancy transition.ElasticMem solves the consistency problem caused by concurrent data accesses via a lightweight table-based scheme combined with data bypassing.It detects correlated read and write requests and serves subsequent read requests with local data.We implement a prototype that realizes ElasticMem based on Memcached.Experiments show that ElasticMem remarkably reduces the time of redundancy transition,the overall latency of correlated concurrent data accesses,and the latency of single data access among them.
基金The National High Technology Research and Develop-ment Program of China(863Program)(No.2006AA01Z263)the National Natural Science Foundation of China(No.60672081)+1 种基金the Natural Science Foundation of Jiangsu Province(No.BK2006502)the Open Research Fund of National Mobile Communications Research Laboratory of Southeast Uni-versity(No.2008N01)
文摘An incremental redundancy hybrid automatic repeat- request （IR-HARQ）scheme based on irregular repeat-accumulate （IRA）codes is proposed. The design of rate compatible punctured IRA codes suitable for an IR-HARQ scheme is well formulated and efficiently solved by a linear-programming method, along with a one-dimensional approach for density evolution. Compared to IR-HARQ schemes based on turbo codes, simulation shows that the proposed IR-HARQ schemes based on IRA codes may achieve almost the same performance at a block size of 1 024, but better throughput at a block size of 4 096. The advantages of the proposed scheme in implementation, including decoding complexity and parallelism, make it more attractive in practice than the IR-HARQ schemes based on both turbo and LDPC codes.
文摘This paper presents a new test data compression/decompression method for SoC testing,called hybrid run length codes. The method makes a full analysis of the factors which influence test parameters：compression ratio,test application time, and area overhead. To improve the compression ratio, the new method is based on variable-to-variable run length codes,and a novel algorithm is proposed to reorder the test vectors and fill the unspecified bits in the pre-processing step. With a novel on-chip decoder, low test application time and low area overhead are obtained by hybrid run length codes. Finally, an experimental comparison on ISCAS 89 benchmark circuits validates the proposed method
基金National Natural Science Foundation of China under Grant No. 60903196,60903175National Critical Patented Projects in the Next Generation Broadband Wireless Mobile Communication Network under Grant No. 2010ZX03006-001-01+1 种基金National High Technical Research and Development Program of China under Grant No. 2009AA01Z418Educational Commission of Hubei Province of China under Grant No. D20114401
文摘Although the wireless network is widely used in many fields,its characteristics such as high bit error rate and broadcast links may block its development.Network coding is an artistic way to exploit its intrinsic characteristics to increase the network reliability.Some people research network coding schemes for inter-flow or intra-flow,each type with its own advantages and disadvantages.In this paper,we propose a new mechanism,called MM-NCOPE,which integrates the idea of inter-flow and intra-flow coding.On the one hand,MM-NCOPE utilizes random liner coding to encode the NCOPE packets while NCOPE is a sub-protocol for optimizing the COPE algorithm by iteration.In NCOPE,packets are automatically matched by size to be coded.As a result,it improves the coding gain in some level.On the other hand,we adopt the partial Acknowledgement retransmission scheme to achieve high compactness and robustness.ACK is an independent packet with the highest priority rather than a part of the data packets.Compared with existing works on opportunistic network coding,our approach ensures the reliability of wireless links and improves the coding gain.
基金supported by the National High Technology Research and Development Program(No.2006AA10Z173 and 2006011001020)the Natural Science Foundation of Shandong Province(Y2007D48)
文摘In order to exploit the evolution and find novel low-molecular-weight glutenin subunit （LMW-GS） for improvement of common wheat quality, thirteen variants from a somatic hybrid introgression line II-12 between Triticum aestivum cv. Jinan 177 （JN177） and Agropyron elongatum were characterized via genomic PCR. Four clones were pseudogenes because they contained an internal stop codon. The remaining nine variants contained intact open reading frames （ORFs）. Sequence alignment indicates that the proteins deduced from the nine ORFs have similar primary structure with LMW-GS cloned from its parents previously. However, they have some unique modifications in the structures. For example, EU292737 contains not only an extra Cys residue in the C-terminal domain but also a long repetitive domain. Both EU 159511 and EU292738 start their first Cys residue in the N-terminal repetitive domain, but not in the N-conserved domain traditionally. These structural alterations may have positive contributions to wheat flour quality. The results of phylogeny showed that most LMW-GS variances from 11-12 were homologous to those from parent JN177 and other wheat lines. The reason for quick evolution of LMW-GS in 11-12 was discussed.
基金supported by the National Natural Science Foundation of China(61371099)the Fundamental Research Funds for the Central Universities of China(HEUCF150812/150810)
文摘Fountain codes are considered to be a promising coding technique in underwater acoustic communication（UAC） which is challenged with the unique propagation features of the underwater acoustic channel and the harsh marine environment. And Luby transform（LT） codes are the first codes fully realizing the digital fountain concept. However, in conventional LT encoding/decoding algorithms, due to the imperfect coverage（IC） of input symbols and short cycles in the generator matrix, stopping sets would occur and terminate the decoding. Thus, the recovery probability is reduced,high coding overhead is required and decoding delay is increased.These issues would be disadvantages while applying LT codes in underwater acoustic communication. Aimed at solving those issues, novel encoding/decoding algorithms are proposed. First,a doping and non-uniform selecting（DNS） encoding algorithm is proposed to solve the IC and the generation of short cycles problems. And this can reduce the probability of stopping sets occur during decoding. Second, a hybrid on the fly Gaussian elimination and belief propagation（OFG-BP） decoding algorithm is designed to reduce the decoding delay and efficiently utilize the information of stopping sets. Comparisons via Monte Carlo simulation confirm that the proposed schemes could achieve better overall decoding performances in comparison with conventional schemes.
基金Supported by the National Natural Science Foundation of China(No.61871322,61771392,61771390,61501373,61271279)the National Science and Technology Major Special Project(2016ZX03001018-004).
文摘Both high-dense wireless connectivity and ultra-huge network capacity are main challenges of next generation broadband networks.As one of its key promising technologies,non-orthogonal multi-ple access(NOMA)scheme can solve those challenges and meet those needs to some extent,in the way that different user equipments(UEs)multiplex on the same resource.Researchers around the world have presented numerous NOMA solutions.Among those,sparse code multiple access(SC-MA)technology is a typical NOMA solution.It supports scheduled access and random access which can be called granted access and grant-free access respectively.But resources allocated to granted UEs and grant-free UEs are strictly separated.In order to improve resource utilization,a hybrid non-orthogonal multiple access scheme is proposed.It allows granted UEs and grant-free UEs sharing the same resource unit in terms of fine-grained integration.On the basis,a resource allocation method is further brought forward based on genetic algorithm.It optimizes resource allocation of all UEs by mapping resource distribution issue to an optimization problem.Comparing throughputs of four meth-ods,simulation results demonstrate the proposed genetic algorithm has better throughput gain.
基金Sponsored by the Nation Nature Science Foundation of China(Grant No. 61201237)the Nature Science Foundation of Heilongjiang Province of China(Grant No. QC2012C069)the Fundationtal Research Funds for the Central Universities (Grant No. HEUCFZ1129, HEUCF130810,HEUCF130817)
文摘Based on the advantage of phase coded signal and stepped frequency signal,a new hybrid modulation signal is introduced in this paper. It combines phase code modulation during the pulse with stepped frequency modulation between the pulses, which is named as phase-coded stepped-frequency ( PCSF ) signal. By analyzing its waveform and ambiguity function,the comparison between Stepped-Frequency ( SF) signal and PCSF signal is given,which shows that the PCSF signal is better than SF signal. Finally,the signal processing method with two stage compressed processing is presented. The simulation results show that this new hybrid modulation radar signal can get a higher stepped frequency than ordinary SF signal,realize the same equivalent bandwidth with less pulse number,and solve the conflict among the stepped frequency,the number of pulse, and transmit average power. Under the premises of a certain range resolution,this new hybrid modulation radar signal not only raises the data rate of radar system,but also reduces Doppler sensitivity with a good prospect, and the effect of one-dimensional range profile is much better than that of traditional SF signal. Therefore,this new hybrid modulation radar signal can be widely used in application.
文摘Hybrid direct sequence and slow frequency hopping spread spectrum multiple access systems (Hybrid DS/SFH SSMA) operating through nonselective slow Rayleigh fading channels was investigated. Multipath and Multiple access interference was taken into account. Expressions of the average error probability for the system were derived. Analytical and numerical results on the average probability of error were presented for the system examined. Random signature sequences and hopping patterns were employed for the system. The numerical results show the effects of the value of M for M ary frequency shift keying (MFSK) modulation and Reed Solomon (RS) coding on the system’s performance. The comparison between RS coded system and noncode system shows that error correction coding is essential to improve the system’s performance.
文摘This paper extends the work on cross-layer design which combines adaptive modulation and coding at the physical layer and hybrid automatic repeat request protocol at the data link layer. By contrast with previous works on this topic, the present development and the performance analysis as well, is based on rate compatible punctured turbo codes. Rate compatibility provides incremental redundancy in transmission of parity bits for error correction at the data link layer. Turbo coding and iterative decoding gives lower packet error rate values in low signal-to-noise ratio regions of the adaptive modulation and coding (AMC) schemes. Thus, the applied cross-layer design results in AMC schemes can achieve better spectral efficiency than convolutional one while it retains the QoS requirements at the application layer. Numerical results in terms of spectral efficiency for both turbo and convolutional rate compatible punctured codes are presented. For a more comprehensive presentation, the performance of rate compatible LDPC is contrasted with turbo case as well as the performance complexity is discussed for each of the above codes.
文摘In the recent era of software development,reusing software is one of the major activities that is widely used to save time.To reuse software,the copy and paste method is used and this whole process is known as code cloning.This activity leads to problems like difficulty in debugging,increase in time to debug and manage software code.In the literature,various algorithms have been developed to find out the clones but it takes too much time as well as more space to figure out the clones.Unfortunately,most of them are not scalable.This problem has been targeted upon in this paper.In the proposed framework,authors have proposed a new method of identifying clones that takes lesser time to find out clones as compared with many popular code clone detection algorithms.The proposed framework has also addressed one of the key issues in code clone detection i.e.,detection of near-miss(Type-3)and semantic clones(Type-4)with significant accuracy of 95.52%and 92.80%respectively.The present study is divided into two phases,the first method converts any code into an intermediate representation form i.e.,Hashinspired abstract syntax trees.In the second phase,these abstract syntax trees are passed to a novel approach“Similarity-based self-adjusting hash inspired abstract syntax tree”algorithm that helps in knowing the similarity level of codes.The proposed method has shown a lot of improvement over the existing code clones identification methods.
文摘Low-Emissivity Hybrid Insulation has been developed in South Korea. It combines both resistive and reflective insulating principle. It is composed with many layers of reflective aluminum foils and honeycomb-structure air cells with polyethylene foam. This paper introduces recent South Korean building insulation code and the applications of Low-Emissivity Hybrid Insulation to meet the code.
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The feasibility of the hybrid chaotic sequences as the spreading codes in code divided multiple access(CDMA) system is analyzed. The design and realization of the digital hybrid chaotic sequence generator by very high speed integrated circuit hardware description language(VHDL) are described. A valid hazard canceledl method is presented. Computer simulations show that the stable digital sequence waveforms can be produced. The correlations of the digital hybrid chaotic sequences are compared with those of m-sequences. The results show that the correlations of the digital hybrid chaotic sequences are almost as good as those of m-sequences. The works in this paper explored a road for the practical applications of chaos.
