Digital content such as games,extended reality(XR),and movies has been widely and easily distributed over wireless networks.As a result,unauthorized access,copyright infringement by third parties or eavesdroppers,and ...Digital content such as games,extended reality(XR),and movies has been widely and easily distributed over wireless networks.As a result,unauthorized access,copyright infringement by third parties or eavesdroppers,and cyberattacks over these networks have become pressing concerns.Therefore,protecting copyrighted content and preventing illegal distribution in wireless communications has garnered significant attention.The Intelligent Reflecting Surface(IRS)is regarded as a promising technology for future wireless and mobile networks due to its ability to reconfigure the radio propagation environment.This study investigates the security performance of an uplink Non-Orthogonal Multiple Access(NOMA)system integrated with an IRS and employing Fountain Codes(FCs).Specifically,two users send signals to the base station at separate distances.A relay receives the signal from the nearby user first and then relays it to the base station.The IRS receives the signal from the distant user and reflects it to the relay,which then sends the reflected signal to the base station.Furthermore,a malevolent eavesdropper intercepts both user and relay communications.We construct mathematical equations for Outage Probability(OP),throughput,diversity evaluation,and Interception Probability(IP),offering quantitative insights to assess system security and performance.Additionally,OP and IP are analyzed using a Deep Neural Network(DNN)model.A deeper comprehension of the security performance of the IRS-assisted NOMA systemin signal transmission is provided by Monte Carlo simulations,which are also carried out to confirm the theoretical conclusions.展开更多
In this paper,an efficient unequal error protection(UEP)scheme for online fountain codes is proposed.In the buildup phase,the traversing-selection strategy is proposed to select the most important symbols(MIS).Then,in...In this paper,an efficient unequal error protection(UEP)scheme for online fountain codes is proposed.In the buildup phase,the traversing-selection strategy is proposed to select the most important symbols(MIS).Then,in the completion phase,the weighted-selection strategy is applied to provide low overhead.The performance of the proposed scheme is analyzed and compared with the existing UEP online fountain scheme.Simulation results show that in terms of MIS and the least important symbols(LIS),when the bit error ratio is 10-4,the proposed scheme can achieve 85%and 31.58%overhead reduction,respectively.展开更多
Airborne networks（ANs） are special types of ad hoc networks that can be used to enhance situational awareness, flight coordination and flight efficiency in civil and military aviation.Compared to ground networks, AN...Airborne networks（ANs） are special types of ad hoc networks that can be used to enhance situational awareness, flight coordination and flight efficiency in civil and military aviation.Compared to ground networks, ANs have some unique attributes including high node mobility, frequent topology changes, mechanical and aerodynamic constrains, strict safety requirements and harsh communication environment.Thus, the performance of conventional transmission control protocol（TCP） will be dramatically degraded in ANs.Aircraft commonly have two or more heterogeneous network interfaces which offer an opportunity to form multiple communication paths between any two nodes in ANs.To satisfy the communication requirements in ANs, we propose aeronautical multipath transport protocol（Aero MTP） for ANs, which effectively utilizes the available bandwidth and diversity provided by heterogeneous wireless paths.Aero MTP uses fountain codes as forward error correction（FEC） codes to recover from data loss and deploys a TCP-friendly rate-based congestion control mechanism for each path.Moreover, we design a packet allocation algorithm based on optimization to minimize the delivery time of blocks.The performance of Aero MTP is evaluated through OMNe T＋＋ simulations under a variety of test scenarios.Simulations demonstrate that Aero MTP is of great potential to be applied to ANs.展开更多
Based on the anti-jamming performance of differential frequency hopping （DFH） systems in Additive White Gaussian Noise （AWGN） channel, Fountain code is introduced to the DFH systems as the outer error correcting c...Based on the anti-jamming performance of differential frequency hopping （DFH） systems in Additive White Gaussian Noise （AWGN） channel, Fountain code is introduced to the DFH systems as the outer error correcting code in this paper to investigate the improvements against partial-band jamming over AWGN channel. The performance of Fountain coded DFH is theoretically analyzed and numerically simulated. The total frequency of hopping in the simulation is 16, and results show that, on one hand, when exact jamming state information （JSI） is available, and the number of jamming frequency is n= 16, the bit error rate （BER） of 10~3 is achieved with the signal to interference ratio （SIR） approximately 7.5 dB over AWGN channel, and the performance improves about 1-1.5dB compared with the no-coded system. When the number of jamming frequency is n=2, the performance increases 15-17dB. On the other hand, when JSI is unavailable, a joint JSI estimation and decoding algorithm is proposed. The BER of 10 3 is achieved with jamming-frequency n 16, SIR=8dB and signal noise ratio （SNR） 10dB over AWGN channel. It＇s proved that this algorithm provides robust anti-jamming pertbrmance even without JSI. The anti-jamming performance of Fountain coded DFH systems is obviously superior to no-coded DFH systems.展开更多
In relay-assisted multi-user system, relay coding is important to enhance the robustness and reliability of cooperative transmission. For better adaptability and efficiency, two joint network and fountain coding(JNFC)...In relay-assisted multi-user system, relay coding is important to enhance the robustness and reliability of cooperative transmission. For better adaptability and efficiency, two joint network and fountain coding(JNFC) schemes are proposed. When the condition of all direct channels is worse, JNFC scheme based on distributed LT(DLT) codes is used. Otherwise, JNFC scheme based on multi-dimensional LT(MD-LT) codes is suited. For both two above-mentioned schemes, the united degree distribution design method for short-length fountain codes is proposed. For the latter scheme, MD-LT codes are proposed for equal error protection(EEP) of each user. Simulation results and analysis show that the united degree distribution need less decoding overhead compared with other degree distribution for short-length fountain codes. And then, all users are protected equally in despite of asymmetric uplinks.展开更多
This paper proposed a practical- feedback scheme for fountain codes based transportprotocol in space communications. In the proposed scheme, the sender is signaled by two types of acknowledgment （ACK） packets.Before...This paper proposed a practical- feedback scheme for fountain codes based transportprotocol in space communications. In the proposed scheme, the sender is signaled by two types of acknowledgment （ACK） packets.Before decoding, packet loss probability isestimated on the receiver side and encapsulated intoa soft ACKand sent to the sender.After decoding,decoding results are encapsulated into hard ACKsandsent to the sender. There are two contributionsin the proposed scheme： 1. Empl layer calculation instead layer statistics to estimate oying physical of application the packet loss probability of space channel, which can improvethe accuracy and practicality. 2. A cascade overhead-failure probability relationship between the sender and the receiver has been analyzed to help determine the exact numberof packetsneeded byfountain decoding.Simulations show that for space communications,compared with the existing space transport protocols, fountain codes based transport protoeolwith the proposed schemecan not only ensure transmission reliability, but also greatly improvelink utilization.展开更多
Digital fountain is applied into deep space communication for its rateless and non-feedback forward error correction.However,the long code length and encoding overhead are confined factors to guarantee a considerable ...Digital fountain is applied into deep space communication for its rateless and non-feedback forward error correction.However,the long code length and encoding overhead are confined factors to guarantee a considerable recovery probability as power and buffer-limited equipment in deep space environment.At the same time,the typical fountain decoding is sub-optimum decoding algorithm.We propose a new approach,Dependent Sequences Compensation Algorithm(DSCA),to improve the encoding efficiency by restricting the randomness in fountain encoding.While decoding algorithm is also optimized by redundant information in stopping set.The results show that the optimized method can obtain a 10-4 decoding failure rate with overhead under 0.20 for code length 500,which indicates the usefulness of the proposed approach in deep space communication.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
To enhance encoding efficiency, an unequal error protection （UEP） broadcast scheme based on one additional feedback is proposed. Different from the equal probability selection for source packets in traditional fount...To enhance encoding efficiency, an unequal error protection （UEP） broadcast scheme based on one additional feedback is proposed. Different from the equal probability selection for source packets in traditional fountain encoding, the proposed scheme calculates the packet loss ratio （PLR） according to the feedback results in systematic broadcast phase （SBP） and then optimizes the selection probability for source packets to guarantee higher level error protection for those source packets with larger PLRs. Thus the amount of unnecessarily redundant encoded packets during encoding broadcast phase （EBP） is decreased significantly. Numerical results show that the proposed scheme can recover 60% more packets than the traditional non-feedback broadcast scheme at the ex- pense of tolerably only one feedback procedure.展开更多
Multicast is an efficient way to support emerging multimedia services over wireless network. Fountain codes are used in multicast systems to enable a robust transmission without CSI feedback and ARQ. We propose a coop...Multicast is an efficient way to support emerging multimedia services over wireless network. Fountain codes are used in multicast systems to enable a robust transmission without CSI feedback and ARQ. We propose a cooperative multicast scheme based on fountain code to improve the performance of multicast. The users are coordinated with each other to decode the message at different time slots within the data transmission of a multicast session. Speci?cally, we take the local channel state information (CSI) and the local residual energy information (REI) into consideration, and apply a relay-selection and power-allocation strategy in our cooperative multicast scheme to prolong the network lifetime, while keeping the transmission delay as low as possible. The simulation results show that the proposed scheme can achieve a good tradeoff between transmission delay and network lifetime.展开更多
As a new class of forward error correcting encoding algorithm,Luby Transform codes are suitable for the erasure channel environment based on the packet communication.The encoding,decoding algorithms and the implementa...As a new class of forward error correcting encoding algorithm,Luby Transform codes are suitable for the erasure channel environment based on the packet communication.The encoding,decoding algorithms and the implementation of LT codes are summarized in the paper.Meanwhile simulations of the ideal soliton distribution and robust soliton distribution are conducted to evaluate the performance of LT codes in terms of successful decoding probability,mean degree and decoding time over the erasure channel.The parameter optimization rules of LT codes are deeply discussed and proposed in the paper.The research results are of great practical importance for improving the real time performance in the erasure correction applications.展开更多
Fountain codes provide an efficient way to transfer information over erasure channels like the Internet. LT codes are the first codes fully realizing the digital fountain concept. They are asymptotically optimal ratel...Fountain codes provide an efficient way to transfer information over erasure channels like the Internet. LT codes are the first codes fully realizing the digital fountain concept. They are asymptotically optimal rateless erasure codes with highly efficient encoding and decoding algorithms. In theory, for each encoding symbol of LT codes, its degree is randomly chosen according to a predetermined degree distribution, and its neighbours used to generate that encoding symbol are chosen uniformly at random. Practical implementation of LT codes usually realizes the randomness through pseudo-randomness number generator like linear congruential method. This paper applies the pseudo-randomness of chaotic sequence in the implementation of LT codes. Two Kent chaotic maps are used to determine the degree and neighbour（s） of each encoding symbol. It is shown that the implemented LT codes based on chaos perform better than the LT codes implemented by the traditional pseudo-randomness number generator.展开更多
LT codes are practical realization of digital fountain codes, which provides the concept of rateless coding. In this scheme, encoded symbols are generated infinitely from k information symbols. Decoder uses only(1+α)...LT codes are practical realization of digital fountain codes, which provides the concept of rateless coding. In this scheme, encoded symbols are generated infinitely from k information symbols. Decoder uses only(1+α)k number of encoded symbols to recover the original information. The degree distribution function in the LT codes helps to generate a random graph also referred as tanner graph. The artifact of tanner graph is responsible for computational complexity and overhead in the LT codes. Intuitively, a well designed degree distribution can be used for an efficient implementation of LT codes. The degree distribution function is studied as a function of power law, and LT codes are classified into two different categories: SFLT and RLT codes. Also, two different degree distributions are proposed and analyzed for SFLT codes which guarantee optimal performance in terms of computational complexity and overhead.展开更多
基金supported in part by Vietnam National Foundation for Science and Technology Development(NAFOSTED)under Grant 102.04-2021.57in part by Culture,Sports and Tourism R&D Program through the Korea Creative Content Agency grant funded by the Ministry of Culture,Sports and Tourism in 2024(Project Name:Global Talent Training Program for Copyright Management Technology in Game Contents,Project Number:RS-2024-00396709,Contribution Rate:100%).
文摘Digital content such as games,extended reality(XR),and movies has been widely and easily distributed over wireless networks.As a result,unauthorized access,copyright infringement by third parties or eavesdroppers,and cyberattacks over these networks have become pressing concerns.Therefore,protecting copyrighted content and preventing illegal distribution in wireless communications has garnered significant attention.The Intelligent Reflecting Surface(IRS)is regarded as a promising technology for future wireless and mobile networks due to its ability to reconfigure the radio propagation environment.This study investigates the security performance of an uplink Non-Orthogonal Multiple Access(NOMA)system integrated with an IRS and employing Fountain Codes(FCs).Specifically,two users send signals to the base station at separate distances.A relay receives the signal from the nearby user first and then relays it to the base station.The IRS receives the signal from the distant user and reflects it to the relay,which then sends the reflected signal to the base station.Furthermore,a malevolent eavesdropper intercepts both user and relay communications.We construct mathematical equations for Outage Probability(OP),throughput,diversity evaluation,and Interception Probability(IP),offering quantitative insights to assess system security and performance.Additionally,OP and IP are analyzed using a Deep Neural Network(DNN)model.A deeper comprehension of the security performance of the IRS-assisted NOMA systemin signal transmission is provided by Monte Carlo simulations,which are also carried out to confirm the theoretical conclusions.
基金supported by the National Natural Science Foundation of China(61601147)the Beijing Natural Science Foundation(L182032)。
文摘In this paper,an efficient unequal error protection(UEP)scheme for online fountain codes is proposed.In the buildup phase,the traversing-selection strategy is proposed to select the most important symbols(MIS).Then,in the completion phase,the weighted-selection strategy is applied to provide low overhead.The performance of the proposed scheme is analyzed and compared with the existing UEP online fountain scheme.Simulation results show that in terms of MIS and the least important symbols(LIS),when the bit error ratio is 10-4,the proposed scheme can achieve 85%and 31.58%overhead reduction,respectively.
文摘Airborne networks（ANs） are special types of ad hoc networks that can be used to enhance situational awareness, flight coordination and flight efficiency in civil and military aviation.Compared to ground networks, ANs have some unique attributes including high node mobility, frequent topology changes, mechanical and aerodynamic constrains, strict safety requirements and harsh communication environment.Thus, the performance of conventional transmission control protocol（TCP） will be dramatically degraded in ANs.Aircraft commonly have two or more heterogeneous network interfaces which offer an opportunity to form multiple communication paths between any two nodes in ANs.To satisfy the communication requirements in ANs, we propose aeronautical multipath transport protocol（Aero MTP） for ANs, which effectively utilizes the available bandwidth and diversity provided by heterogeneous wireless paths.Aero MTP uses fountain codes as forward error correction（FEC） codes to recover from data loss and deploys a TCP-friendly rate-based congestion control mechanism for each path.Moreover, we design a packet allocation algorithm based on optimization to minimize the delivery time of blocks.The performance of Aero MTP is evaluated through OMNe T＋＋ simulations under a variety of test scenarios.Simulations demonstrate that Aero MTP is of great potential to be applied to ANs.
基金the National Natural Science Foundation of China under Grant 61371125
文摘Based on the anti-jamming performance of differential frequency hopping （DFH） systems in Additive White Gaussian Noise （AWGN） channel, Fountain code is introduced to the DFH systems as the outer error correcting code in this paper to investigate the improvements against partial-band jamming over AWGN channel. The performance of Fountain coded DFH is theoretically analyzed and numerically simulated. The total frequency of hopping in the simulation is 16, and results show that, on one hand, when exact jamming state information （JSI） is available, and the number of jamming frequency is n= 16, the bit error rate （BER） of 10~3 is achieved with the signal to interference ratio （SIR） approximately 7.5 dB over AWGN channel, and the performance improves about 1-1.5dB compared with the no-coded system. When the number of jamming frequency is n=2, the performance increases 15-17dB. On the other hand, when JSI is unavailable, a joint JSI estimation and decoding algorithm is proposed. The BER of 10 3 is achieved with jamming-frequency n 16, SIR=8dB and signal noise ratio （SNR） 10dB over AWGN channel. It＇s proved that this algorithm provides robust anti-jamming pertbrmance even without JSI. The anti-jamming performance of Fountain coded DFH systems is obviously superior to no-coded DFH systems.
基金supported in part by a grant from the Ph.D. Programs Foundation of Ministry of Education of China under Grants No. 20094307110004National Natural Science Foundation of China under Grants No.61372098, No.61101074Natural Science Foundation of Hunan Province, China under Grants No.12jj2037
文摘In relay-assisted multi-user system, relay coding is important to enhance the robustness and reliability of cooperative transmission. For better adaptability and efficiency, two joint network and fountain coding(JNFC) schemes are proposed. When the condition of all direct channels is worse, JNFC scheme based on distributed LT(DLT) codes is used. Otherwise, JNFC scheme based on multi-dimensional LT(MD-LT) codes is suited. For both two above-mentioned schemes, the united degree distribution design method for short-length fountain codes is proposed. For the latter scheme, MD-LT codes are proposed for equal error protection(EEP) of each user. Simulation results and analysis show that the united degree distribution need less decoding overhead compared with other degree distribution for short-length fountain codes. And then, all users are protected equally in despite of asymmetric uplinks.
基金supported by the National Natural Science Foundation of China (NSFC) under grant No. 61132002National Program on Key Basic Research Project of China (973 Program) under grant No. 2014CB340206+1 种基金the Creative Research Groups of NSFC under grant No. 61321061Aerospace Communications and Terminal Application Technologies Engineering Laboratory in Shenzhen under No.JCYJ20120619140254275
文摘This paper proposed a practical- feedback scheme for fountain codes based transportprotocol in space communications. In the proposed scheme, the sender is signaled by two types of acknowledgment （ACK） packets.Before decoding, packet loss probability isestimated on the receiver side and encapsulated intoa soft ACKand sent to the sender.After decoding,decoding results are encapsulated into hard ACKsandsent to the sender. There are two contributionsin the proposed scheme： 1. Empl layer calculation instead layer statistics to estimate oying physical of application the packet loss probability of space channel, which can improvethe accuracy and practicality. 2. A cascade overhead-failure probability relationship between the sender and the receiver has been analyzed to help determine the exact numberof packetsneeded byfountain decoding.Simulations show that for space communications,compared with the existing space transport protocols, fountain codes based transport protoeolwith the proposed schemecan not only ensure transmission reliability, but also greatly improvelink utilization.
基金Supported by the National Natural Sciences Foundation of China (No. 61032003)
文摘Digital fountain is applied into deep space communication for its rateless and non-feedback forward error correction.However,the long code length and encoding overhead are confined factors to guarantee a considerable recovery probability as power and buffer-limited equipment in deep space environment.At the same time,the typical fountain decoding is sub-optimum decoding algorithm.We propose a new approach,Dependent Sequences Compensation Algorithm(DSCA),to improve the encoding efficiency by restricting the randomness in fountain encoding.While decoding algorithm is also optimized by redundant information in stopping set.The results show that the optimized method can obtain a 10-4 decoding failure rate with overhead under 0.20 for code length 500,which indicates the usefulness of the proposed approach in deep space communication.
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 China National S&T Major Project(2013ZX03003002003)the National Natural Science Foundation of China(61371075)"111"Project of China(B14010)
文摘To enhance encoding efficiency, an unequal error protection （UEP） broadcast scheme based on one additional feedback is proposed. Different from the equal probability selection for source packets in traditional fountain encoding, the proposed scheme calculates the packet loss ratio （PLR） according to the feedback results in systematic broadcast phase （SBP） and then optimizes the selection probability for source packets to guarantee higher level error protection for those source packets with larger PLRs. Thus the amount of unnecessarily redundant encoded packets during encoding broadcast phase （EBP） is decreased significantly. Numerical results show that the proposed scheme can recover 60% more packets than the traditional non-feedback broadcast scheme at the ex- pense of tolerably only one feedback procedure.
文摘Multicast is an efficient way to support emerging multimedia services over wireless network. Fountain codes are used in multicast systems to enable a robust transmission without CSI feedback and ARQ. We propose a cooperative multicast scheme based on fountain code to improve the performance of multicast. The users are coordinated with each other to decode the message at different time slots within the data transmission of a multicast session. Speci?cally, we take the local channel state information (CSI) and the local residual energy information (REI) into consideration, and apply a relay-selection and power-allocation strategy in our cooperative multicast scheme to prolong the network lifetime, while keeping the transmission delay as low as possible. The simulation results show that the proposed scheme can achieve a good tradeoff between transmission delay and network lifetime.
文摘水声网络(underwater acoustic network,UAN)具有长传播时延、高误码率、半双工通信等特性,这些特性严重影响了UAN中数据的可靠传输。而在线喷泉码具有在线控制、编解码复杂度低、码率自适应等诸多优势,在线喷泉码适合于保障UAN中数据的可靠传输。针对递归与限制反馈的在线喷泉码(recursive OFC with limited feedback,ROFC-LF)存在不理想覆盖和4元环问题导致略高的开销和频繁的反馈,提出适用于UAN的基于优先级与可Zigzag解码的ROFC-LF(priority-based and zigzag-decodable ROFC-LF,P-ZROFC-LF)。P-ZROFC-LF在建立阶段选取具有最高优先级的原始包进行编码直至所有原始包均参与编码。同时,引入可Zigzag解码编码,将无用编码包进行移位异或转换为有用编码包来提高解码性能。通过随机图理论,分析P-ZROFC-LF所需编码包数与原始包数之间的关系。理论分析与仿真结果表明,与大部分在线喷泉码相比,P-ZROFC-LF显著提高了反馈和开销性能。其中P-ZROFC-LF相比于ROFC-LF的反馈和开销分别减少了18%和0.0176,更适用于UAN。
基金supported by Zhongguancun Haidian Science Park Postdoctoral Special Fund
文摘As a new class of forward error correcting encoding algorithm,Luby Transform codes are suitable for the erasure channel environment based on the packet communication.The encoding,decoding algorithms and the implementation of LT codes are summarized in the paper.Meanwhile simulations of the ideal soliton distribution and robust soliton distribution are conducted to evaluate the performance of LT codes in terms of successful decoding probability,mean degree and decoding time over the erasure channel.The parameter optimization rules of LT codes are deeply discussed and proposed in the paper.The research results are of great practical importance for improving the real time performance in the erasure correction applications.
基金Project supported in part by the National Natural Science Foundation of China (Grant Nos 60774088 and 10772135)the Program for New Century Excellent Talents in University of China (NCET)the Foundation of the Application Base and Frontier Technology Research Project of Tianjin (Grant Nos 08JCZDJC21900 and 07CYBJC05800)
文摘Fountain codes provide an efficient way to transfer information over erasure channels like the Internet. LT codes are the first codes fully realizing the digital fountain concept. They are asymptotically optimal rateless erasure codes with highly efficient encoding and decoding algorithms. In theory, for each encoding symbol of LT codes, its degree is randomly chosen according to a predetermined degree distribution, and its neighbours used to generate that encoding symbol are chosen uniformly at random. Practical implementation of LT codes usually realizes the randomness through pseudo-randomness number generator like linear congruential method. This paper applies the pseudo-randomness of chaotic sequence in the implementation of LT codes. Two Kent chaotic maps are used to determine the degree and neighbour（s） of each encoding symbol. It is shown that the implemented LT codes based on chaos perform better than the LT codes implemented by the traditional pseudo-randomness number generator.
基金supported by Research Fund Chosun Univerity,2011
文摘LT codes are practical realization of digital fountain codes, which provides the concept of rateless coding. In this scheme, encoded symbols are generated infinitely from k information symbols. Decoder uses only(1+α)k number of encoded symbols to recover the original information. The degree distribution function in the LT codes helps to generate a random graph also referred as tanner graph. The artifact of tanner graph is responsible for computational complexity and overhead in the LT codes. Intuitively, a well designed degree distribution can be used for an efficient implementation of LT codes. The degree distribution function is studied as a function of power law, and LT codes are classified into two different categories: SFLT and RLT codes. Also, two different degree distributions are proposed and analyzed for SFLT codes which guarantee optimal performance in terms of computational complexity and overhead.
