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Dissertations / Theses on the topic 'Fountain codes'
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Hu, Ketai. "Reduced-complexity decoding of fountain codes." Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27254.
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Fountain codes are a universal class of rateless codes originally designed for erasure channels. Naturally adapting to channel states without channel knowledge at the transmitter, Fountain codes have recently been demonstrated also as an appealing solution for communication over fading channels. However, their relatively high decoding complexity limits their practical use in a wireless setting. In this thesis, we present a new decoding algorithm for Raptor codes---a type of Fountain codes---over fading channels, where the complexity is significantly reduced without sacrifice of performance.
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PAIBA, FRANKLIN ANTONIO SANCHEZ. "BIDIMENSIONAL FOUNTAIN CODES FOR ERASURE CHANNELS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2008. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=12457@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOREsta dissertação aborda o estudo de códigos fontanais (códigos LT e códigos Raptor) que são uma classe de códigos criados para a transmissão de dados de maneira confiável e eficiente através de canais os quais podem ser modelados como canais com apagamento. Os códigos LT e códigos Raptor são denominados códigos fontanais, devido a que eles são uma boa aproximação para o conceito de fontanas digitais. Além disso, eles são classificados como códigos de taxa versátil, no sentido que o número de símbolos codificados que podem ser gerados a partir dos dados de entrada é potencialmente ilimitado. Códigos LT são capazes de recuperar, com probabilidade maior do que (1 − delta), um conjunto de k símbolos de entrada a partir de quaisquer k + O((raiz quadrada de k)(ln(2))(k/delta)) símbolos codificados recebidos, com uma média de O(k ln(k/delta)) operações XOR. Os códigos Raptor são uma extensão de códigos LT, na qual o processo de codificação é composto de duas etapas: um código de bloco de comprimento fixo (denominado pré- código) e um código LT com uma distribuição de graus apropriada. Investigou-se o desempenho dos códigos LT usando duas novas distribuições de graus (Sóliton Robusta Melhorada e Sóliton Robusta Truncada) e foi proposto um modelo de códigos LT Bidimensionais, na qual os símbolos de entrada são agrupados em forma de matriz. Neste esquema os blocos correspondentes às linhas da matriz são codificados usando um código LT e, em seguida, a matriz resultante tem suas colunas também codificadas usando um código LT. Ainda que a complexidade do esquema tenha sido dobrada o desempenho alcançado pelos códigos LT Bidimensionais superou o desempenho dos códigos LT convencionais para situações em que a qualidade do canal BEC é elevada.
Fountain Codes (LT Codes and Raptor Codes) are a class of codes proposed to efficient and reliably transmit data through Erasure Channels. LT Codes and Raptor Codes are a good approximation to the concept of digital fountain and as such are named as fountain codes. They are said to be rateless codes in the sense that the number of symbols produced by the encoder could grow, potentially, to infinite. With probability of success larger than (1−delta), a decoder of an LT code based scheme can recover the k transmitted symbols from any received block of k + O((square root k)(ln(2))(k/delta)) correct symbols with an average of O(k ln(k/delta)) XOR operations. Raptor codes are an extension of the LT codes idea, with a tandem scheme where a fixed length block code (namely a pre- code) is followed by an LT code that uses a properly chosen degree distribution. In this dissertation the performance of LT codes with two recently proposed degree distributions, the Improved Robust Soliton and the Truncated Soliton Robust Distribution were investigated. A new scheme called Bidimensional LT Codes, has been proposed. In this scheme the input symbols are structured in a matrix form and afterwards the blocks corresponding to the lines of the matrix are encoded with an LT code. The columns of the new matrix so obtained are next encoded with a similar LT code. The complexity of the new scheme is doubled and yet its performance only just surpasses that of the conventional LT scheme for high quality BEC.
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Nguyen, Dang Thanh. "Fountain codes for the wireless Internet." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/64484/.
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In this thesis, novel Foutain codes are proposed for transmission over wireless channels. The thesis concentrates on a specific version of Fountain codes, namely on Luby transform codes. More specifically, we consider their concatenation with classic error correction codes, yielding schemes, such as the concatenated Luby Transform and Bit Interleaved Coded Modulation using Iterative Decoding (LT-BICM-ID), the amalgamated Luby Transform and Generalized Low Density Parity Check (LT-GLDPC) code, or the Luby Transform coded Spatial Division Multiple Access (LT-SDMA) scenario considered. The thesis also investigates the potential of Systematic Luby Transform (SLT) codes using soft-bit decoding and analyses their Bit Error Ratio (BER) performance using EXtrinsic Information Transfer (EXIT) charts. SLT codes using different degree distributions and random integer packet index generation algorithms for creating the parity and information part of the SLT codeword are also investigated in this thesis. For the sake of improving both the BER performance and the diversity gain of Vertical Bell Laboratories Layered Space Time (V-BLAST) schemes, in this thesis a SLT coded V-BLAST system having four transmit and four receive antennas is proposed. Finally, A Hybrid Automatic Repeat reQuest (H-ARQ) SLT coded modulation scheme is designed in this thesis, where SLT codes are used both for correcting erroneous bits and for detecting as well as retransmitting erroneous Internet Protocol (IP) based packets. Erroneous IP packet detection is implemented using syndrome checking with the aid of the SLT codes’ Parity Check Matrix (PCM). Optimizing the mapping of SLT-encoded bits to modulated symbols and then using iterative decoding for exchanging extrinsic information between the SLT decoder and the demapper substantially improves the achievable Bit Error Ratio (BER) performance of the scheme.
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Lázaro, Blasco Francisco [Verfasser]. "Fountain Codes under Maximum Likelihood Decoding / Francisco Lázaro Blasco." München : Verlag Dr. Hut, 2017. http://d-nb.info/1137023546/34.
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Grobler, Trienko Lups. "Fountain codes and their typical application in wireless standards like edge." Diss., University of Pretoria, 2008. http://hdl.handle.net/2263/25381.
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One of the most important technologies used in modern communication systems is channel coding. Channel coding dates back to a paper published by Shannon in 1948 [1] entitled “A Mathematical Theory of Communication”. The basic idea behind channel coding is to send redundant information (parity) together with a message to make the transmission more error resistant. There are different types of codes that can be used to generate the parity required, including block, convolutional and concatenated codes. A special subclass of codes consisting of the codes mentioned in the previous paragraph, is sparse graph codes. The structure of sparse graph codes can be depicted via a graphical representation: the factor graph which has sparse connections between its elements. Codes belonging to this subclass include Low-Density-Parity-Check (LDPC) codes, Repeat Accumulate (RA), Turbo and fountain codes. These codes can be decoded by using the belief propagation algorithm, an iterative algorithm where probabilistic information is passed to the nodes of the graph. This dissertation focuses on noisy decoding of fountain codes using belief propagation decoding. Fountain codes were originally developed for erasure channels, but since any factor graph can be decoded using belief propagation, noisy decoding of fountain codes can easily be accomplished. Three fountain codes namely Tornado, Luby Transform (LT) and Raptor codes were investigated during this dissertation. The following results were obtained: - The Tornado graph structure is unsuitable for noisy decoding since the code structure protects the first layer of parity instead of the original message bits (a Tornado graph consists of more than one layer).
- The successful decoding of systematic LT codes were verified.
- A systematic Raptor code was introduced and successfully decoded. The simulation results show that the Raptor graph structure can improve on its constituent codes (a Raptor code consists of more than one code).
Dissertation (MEng)--University of Pretoria, 2008.
Electrical, Electronic and Computer Engineering
MEng
unrestricted
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Shirvanimoghaddam, Mahyar. "From binary to analog fountain codes: design, theory, and applications." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/12584.
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The focus of this thesis is on the design of rateless codes for wireless communications. Firstly, I present the design of the binary rateless codes for user cooperation scenarios. A novel partially coded cooperation scheme based on Raptor codes is proposed and analysed by using the AND-OR tree analytical approach. I formulate a degree optimization problem for both conventional and proposed coded cooperation strategies and show that the proposed scheme with optimized degree distribution outperforms the conventional scheme. Secondly, I propose a novel analog fountain code (AFC), where the modulated symbols are directly generated from information symbols in a linear fashion. The AFC can automatically adapt to the unknown wireless channel conditions without requiring channel state information at the transmitter side. It is shown that the AFC can approach the capacity of the Gaussian channel in a wide range of SNR values. Based on the principle of AFC, I then design the near-optimal massive random access scheme for machine to machine (M2M) communications to support a large number of access devices with different delay requirements. I formulate an optimization problem to optimize the access probability for each device and derive the optimal random transmission strategy. Simulation results show that the proposed scheme performs very close to the optimal coordinated scheme. Finally, the binary compressive sensing (CS) problem is studied and is reformulated by using AFCs. A simple verification based decoder is proposed for the noiseless case and the minimum number of measurements to successfully reconstruct the original sparse signal is obtained. I then show a practical application of the AFCS for the sparse event detection (SED) in wireless sensor networks and show that AFCS outperforms existing SED algorithms in terms of the probability of correct detection in different channel conditions even with a smaller number of measurements.
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Lim, Wen Jun. "Analysis and design of analog fountain codes for short packet communications." Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/29277.
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Channel coding is at the heart of any communications systems and plays a key role in meeting the requirements of current and future wireless standards. The services defined by the 3rd Generation Partnership Project (3GPP) for fifth generation (5G) new radio, in particular ultra-reliable low-latency communication (URLLC) and massive machine type communication (mMTC), have very stringent requirements in terms of latency and reliability. Short packet communication is proved to be one of the solutions to achieve the latency requirement of future wireless communication systems due to shorter transmission-time interval. Therefore, designing robust and efficient short channel codes for URLLC and mMTC is of critical importance to design sustainable and efficient mobile communication systems.
Traditional channel coding methods are not able to fulfil the requirements for Beyond 5G (B5G) or 6th generation (6G) mobile standards, which have a strong emphasis on bit-level granularity and flexibility. Rateless codes have been considered as viable candidates for short packet communication in URLLC and mMTC due to their rate-adaptive nature. Furthermore, the fact that rateless codes do not rely on channel state information (CSI) makes them stand out from traditional channel codes, which is an important characteristic to reduce transmission overhead.
Analog fountain code (AFC) is a newly introduced rateless code, which has linear complexity in terms of encoding and decoding, and a capacity-approaching performance for a wide range of signal-to-noise ratios (SNRs). The code structure is simple; that is, the modulated information symbols are directly generated from information symbols in a linear manner. In this thesis, I will take a step forward to provide a comprehensive analysis and design of AFC for short packet communications. I first propose a density evolution (DE)-based framework, which tracks the evolution of the probability density function of the messages exchanged between AFC’s variable and check nodes in the belief propagation (BP) decoder. Based on the proposed DE framework, I formulate an optimisation problem to find the optimal weight set for AFC in order to minimise the bit error rate at a given SNR. Simulation results show the superiority of the AFC code design with optimised weight set compared to existing AFC designs in the literature.
Next, I focus on the design of AFC in a short block length regime. In order to guarantee the performance of AFC in these conditions, a proper precoder is required. Therefore, the optimised weight set obtained from the proposed DE framework can be directly applied in the short block length regime with the aid of a precoder with powerful error correcting capability. Specifically, I use Bose, Chaudhuri, and Hocquenghem (BCH) codes with an ordered statistics decoder (OSD) and low-density parity check (LDPC) codes with the BP decoder. Simulation results show that low rate precoders offer better reliability across a wide range of SNRs compared to high-rate precoders. Additionally, the precoded AFC performs close to the normal approximation benchmark in the short block length regime over a wide range of SNRs. I also discuss the complexity of the AFC decoder and propose a threshold-based decoder to reduce it.
Finally, I focus on the analysis and design of AFC in a multiple access channel. I present two encoding schemes, i.e., superposition coding and joint encoding, and two decoding schemes, i.e., successive interference cancellation and joint decoding, for multiple access AFC (MA-AFC). The process of joint encoding and the updating rules for joint decoding are explained in detail. I propose different combinations of encoding and decoding schemes for MA-AFC and evaluate their performance in terms of block error rate (BLER) to determine which combination has the best performance. Next, I propose a DE-based framework to track the evolution of messages exchanged between check nodes and variable nodes of MA-AFC under the joint decoding scheme. With the proposed DE framework, I formulate optimisation problems to find the optimal AFC code parameters, specifically the weight-set, which minimise the bit error rate at a given SNR. Simulation results show that the optimised AFC code outperforms the existing AFC code design in multiple access scenarios.
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Du, Toit F. J. "A fountain code forward error correction strategy for SensLAB applications." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86399.
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Thesis (MScEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: The discovery of sparse graph codes, used in forward error correction strate- gies, has had an unrivaled impact on Information theory over the past decade. A recent advancement in this field, called Fountain codes, have gained much attention due to its intelligent rate adaptivity, and lend itself to applications such as multicasting and broadcasting networks. These particular properties can be considered valuable in a wireless sensor network setting as it is capable of providing forward error correction, and the added conceptual network protocol related extensions. A wireless sensor network testbed in France, called SensLAB, provides an experimental facility for researchers to develop and evaluate sensor network protocols, aside from a simulation environment. Tremendous value can be added to the SensLAB community if an appropriate forward error correction design, such as Fountain codes, is deemed feasible for use on such a platform. This thesis investigates the use of Fountain codes, in a binary erasure channel environment, as a forward error correction strategy for the distribution of reliable data content over the SensLAB platform. A short message length LT code using two different decoding mechanisms were developed and evaluated for possible implementation. Furthermore, a short message length Raptor code was developed by using supplementary theory and optimisation techniques that permit scalability in terms of the message size. The results favoured the Raptor code design as it performs close to near optimal while still satisfying the rateless- and universality property, at low computational complexity.
AFRIKAANSE OPSOMMING: Die ontdekking van yl-grafiekkodes, van toepassing op foutkorreksie strategieë, het onlangs 'n ongeewenaarde impak op Informasieteorie gehad. In 'n onlangse vooruitgang in hierdie veld, genoem Fonteinkodes, word daar meer fokus geplaas op die intelligente tempo aanpassingsvermoë van hierdie kodes, wat nuttige toepassing kan inhou in multi-saai- en uitsaai netwerke. Hierdie eienskappe kan moontlik as waardevol beskou word in draadlose sensor netwerke weens die fout regstellingsvermoë en die bykomende konseptuele netwerk protokol verwante uitbreidings. 'n Draadlose sensor netwerk toetsplatvorm in Frankryk, genoem die SensLAB, bied navorsers die geleentheid om eksperimentele sensor netwerk protokolle te ontwikkel en te toets buite 'n tipiese simulasie-omgewing. Groot waarde kan bygevoeg word aan die SensLAB gemeenskap indien 'n geskikte foutkorreksie strategie ontwikkel word, soos Fonteinkodes, en as geskik beskou kan word vir hierdie platvorm. In hierdie tesis word Fonteinkodes saam met die SensLAB platvorm ondersoek, binne die raamwerk van 'n binêre verlieskanaal, om vir foutkorreksie oor die verspreiding van betroubare data in SensLAB op te tree. 'n Kort boodskap LT kode word voorgestel deur van twee verskillende dekoderings meganismes gebruik te maak. 'n Alternatief, genaamd Raptorkode, was ook ondersoek. 'n Raptorkode. 'n Kort boodskap Raptor kode, wat ontwikkel is met bykomende teorie en optimeringstegnieke, word ook voorgestel. Die bykomende tegnieke bied 'n skaleerbare boodskap lengte terwyl dit tempoloos en universeel bly, en lae kompleksiteit bied.
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Wang, Xiaohan Sasha. "Investigation of Forward Error Correction Coding Schemes for a Broadcast Communication System." Thesis, University of Canterbury. Computer Science and Software Engineering, 2013. http://hdl.handle.net/10092/7902.
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This thesis investigates four FEC (forward error correction) coding schemes for their suitability
for a broadcast system where there is one energy-rich transmitter and many energy-constrained
receivers with a variety of channel conditions. The four coding schemes are: repetition codes (the
baseline scheme); Reed-Solomon (RS) codes; Luby-Transform (LT) codes; and a type of RS and
LT concatenated codes. The schemes were tested in terms of their ability to achieve both high
average data reception success probability and short data reception time at the receivers (due to
limited energy). The code rate (Rc) is fixed to either 1/2 or 1/3. Two statistical channel models were
employed: the memoryless channel and the Gilbert-Elliott channel. The investigation considered
only the data-link layer behaviour of the schemes. During the course of the investigation, an
improvement to the original LT encoding process was made, the name LTAM (LT codes with
Added Memory) was given to this improved coding method. LTAM codes reduce the overhead
needed for decoding short-length messages. The improvement can be seen for decoding up to
10000 number of user packets. The maximum overhead reduction is as much as 10% over the
original LT codes.
The LT-type codes were found to have the property that can both achieve high success data
reception performance and flexible switch off time for the receivers. They are also adaptable to
different channel characteristics. Therefore it is a prototype of the ideal coding scheme that this
project is looking for. This scheme was then further developed by applying an RS code as an
inner code to further improve the success probability of packet reception. The results show that
LT&RS code has a significant improvement in the channel error tolerance over that of the LT
codes without an RS code applied. The trade-off is slightly more reception time needed and more
decoding complexity. This LT&RS code is then determined to be the best scheme that fulfils the
aim in the context of this project which is to find a coding scheme that both has a high overall data
reception probability and short overall data reception time.
Comparing the LT&RS code with the baseline repetition code, the improvement is in three
aspects. Firstly, the LT&RS code can keep full success rate over channels have approximately
two orders of magnitude more errors than the repetition code. This is for the two channel models
and two code rates tested. Secondly, the LT&RS code shows an exceptionally good performance
under burst error channels. It is able to maintain more than 70% success rate under the long
burst error channels where both the repetition code and the RS code have almost zero success
probability. Thirdly, while the success rates are improved, the data reception time, measured in
terms of number of packets needed to be received at the receiver, of the LT&RS codes can reach a
maximum of 58% reduction for Rc = 1=2 and 158% reduction for Rc = 1=3 compared with both
the repetition code and the RS code at the worst channel error rate that the LT&RS code maintains
almost 100% success probability.
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Huang, Weizheng. "Investigation on Digital Fountain Codes over Erasure Channels and Additive White Gaussian Noise Channels." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1336067205.
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SZABAS, CLAUDIO ALEJANDRO. "FOUNTAIN CODES AND OTHER CHANNEL CODING SCHEMES FOR PROTECTION OF TRANSPORT STREAMS OVER IP NETWORKS WITH PACKET ERASURE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2011. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=17792@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Há, nos dias atuais, uma crescente demanda pelo transporte de video sobre IP, i.e., para distribuição de conteúdo pela Internet, por serviços de IPTV em definição padrão e em alta definição e, mesmo para uso interno nas redes de emissoras tradicionais de televisão, que transportam contribuições de elevada qualidade para seus programas. Em tais aplicações, o conteúdo dos programas é transportado usando MPEG-2 ou MPEG-4, sob a forma de MPEG-2 Transport Streams, encapsulados com protocolos tais como RTP, UDP e IP. As redes IP, que são modelizadas como Redes com Apagamento de Pacotes (PEC) não foram, no entanto, concebidas para o transporte de mídias em tempo real, esbarra portanto em problemas comuns como perdas de pacotes e jitter, gerando perturbações que se refletem na recepção do conteúdo. Os métodos tradicionais para superar estas dificuldades, como por exemplo, os que se baseiam em retransmissões usando protocolos ARQ (Automatic Repeat on Request), não são uma solução eficiente para proteger a transmissão de multimídia em tempo real. A proteção de multimídia transmitida em tempo real via IP recorre, neste caso, aos códigos para canal. Há códigos para canal recomendados em RFC s e Padrões, usados amplamente pelos fabricantes de equipamento. Os modernos Códigos Fontanais, possuem características atraentes para o transporte de conteúdos multimídia em tempo real. Neste trabalho, simulações são realizadas, onde o conteúdo encapsulado em Transport Stream, é protegido com Códigos Fontanais antes do encapsulamento para o envio através da rede. A título de comparação, o experimento é realizado também usando outros códigos para canal recomendados. Para realizar a comparação são usadas medições padronizadas do Transport Stream, medições objetivas como artefatos de blocagem e finalmente uma análise subjetiva do conteúdo recebido é usada. O trabalho conclui com a proposta de um Codificador de canal adaptável para Transport Stream.
There is a growing demand for the transport of video over IP today, i.e., for content distribution over the Internet, IPTV services in Standard and High Definition, or even inside traditional broadcasters networks, transporting broadcast quality contributions to the main program. In such applications, the source encoded MPEG-2 or -4 content is transported in the form of MPEG-2 Transport Streams, encapsulated over network protocols. However, IP networks, which can be modeled as Packet Erasure Networks (PEC), were not originally designed for the transport of real time media. There are problems, such as packet drops and jitter, which generate severe impairments in the content that is decoded at the reception. Traditional methods for overcoming these problems, as for example retransmissions performed by Automatic Repeat Request (ARQ) protocols, are not suitable for real-time multimedia protection. Channel coding is the solution of choice for protecting real-time multimedia over IP. There are channel coding schemes specified in open recommendations and Standards, widely adopted by equipment vendors today. Fountain Codes present very attractive characteristics for the transport of real-time multimedia. In the present work, simulations with a Fountain code, protecting Transport Stream contents prior to network encapsulation, are presented. The experiment if repeated with other channel coding techniques commonly employed today. In order to analyze the decoded contents and obtain comparative results, standardized Transport Stream measurements, objective Blocking Artifacts measurements and subjective analysis of the decoded samples are employed. This work is concluded with the proposal of a Transport Stream Adaptive channel encoder, that is explained in Appendix-B.
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Von, Solms Suné. "Design of effective decoding techniques in network coding networks / Suné von Solms." Thesis, North-West University, 2013. http://hdl.handle.net/10394/9544.
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Random linear network coding is widely proposed as the solution for practical network coding
applications due to the robustness to random packet loss, packet delays as well as network topology
and capacity changes. In order to implement random linear network coding in practical scenarios
where the encoding and decoding methods perform efficiently, the computational complex coding
algorithms associated with random linear network coding must be overcome.
This research contributes to the field of practical random linear network coding by presenting
new, low complexity coding algorithms with low decoding delay. In this thesis we contribute to this
research field by building on the current solutions available in the literature through the utilisation
of familiar coding schemes combined with methods from other research areas, as well as developing
innovative coding methods.
We show that by transmitting source symbols in predetermined and constrained patterns from
the source node, the causality of the random linear network coding network can be used to create
structure at the receiver nodes. This structure enables us to introduce an innovative decoding
scheme of low decoding delay. This decoding method also proves to be resilient to the effects of
packet loss on the structure of the received packets. This decoding method shows a low decoding
delay and resilience to packet erasures, that makes it an attractive option for use in multimedia
multicasting.
We show that fountain codes can be implemented in RLNC networks without changing the
complete coding structure of RLNC networks. By implementing an adapted encoding algorithm at
strategic intermediate nodes in the network, the receiver nodes can obtain encoded packets that
approximate the degree distribution of encoded packets required for successful belief propagation
decoding.
Previous work done showed that the redundant packets generated by RLNC networks can be
used for error detection at the receiver nodes. This error detection method can be implemented
without implementing an outer code; thus, it does not require any additional network resources. We
analyse this method and show that this method is only effective for single error detection, not
correction.
In this thesis the current body of knowledge and technology in practical random linear network
coding is extended through the contribution of effective decoding techniques in practical network
coding networks. We present both analytical and simulation results to show that the developed
techniques can render low complexity coding algorithms with low decoding delay in RLNC networks.Thesis (PhD (Computer Engineering))--North-West University, Potchefstroom Campus, 2013
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Usman, Mohammed. "Assessment of the performance and applicability of fountain codes for multimedia streaming applications and stratergy for their deployment over GPRS systems." Thesis, University of Strathclyde, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501924.
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Jafarizadeh, Saber. "Distributed coding and algorithm optimization for large-scale networked systems." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/13238.
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In this thesis design and optimization of several distributed algorithms in large-scale networked systems is studied. The studied algorithms operate on networks of autonomous agents in general including the sensor networks and the ad hoc networks. The main focus here is on distributed algorithms operating on large-scale networks. This is due to their robustness to node failure and ability to extend according to the size and topology of the system. Regarding the optimization of the studied algorithms, it is aimed to increase their convergence rate to their equilibrium state considering the constraints of the system including the available bandwidth, memory and power for each agent. The first topic addresses the optimization of two algorithms; namely the distributed random gossip algorithm and the distributed average consensus algorithm. The underlying graph of the network is exploited to provide an analytical solution to the semidefinite programming formulation of the problems. In the second topic, two distributed algorithms are proposed for increasing data persistency in wireless sensor networks based on LT and Raptor codes. In the proposed algorithms, the sensed data is disseminated using random walks with the non-uniform stationary distribution. A new distributed method is proposed for assigning the transition probabilities of the random walks. The third topic studies distributed coding of LT codes in Y networks where multiple sources communicate with the same destination through a common relay node. The Adaptive Distributed LT coding algorithm is proposed that combines the LT codes with the network coding technique. The fourth topic addresses optimization of the LT codes for short message lengths. Unlike previous formulations, the provided novel semidefinite programming formulation has finite number of constraints while it is free of approximation.
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Kabore, Wendyida Abraham. "Codage de canal et codage réseau pour les CPL-BE dans le contexte des réseaux Smart Grid." Thesis, Limoges, 2016. http://www.theses.fr/2016LIMO0038/document.
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Ce manuscrit traite de la fiabilisation des CPL-BE dans le contexte smart grid avec l’application des techniques de codage correcteur d’erreurs et d’effacements. Après une introduction sur le concept de smart grid, le canal CPL-BE est caractérisé précisément et les modèles qui le décrivent sont présentés. Les performances des codes à métrique rang, simples ou concaténés avec des codes convolutifs, particulièrement intéressants pour combattre le bruit criss-cross sur les réseaux CPL-BE sont simulées et comparées aux performances des codes Reed-Solomon déjà présents dans plusieurs standards. Les codes fontaines qui s’adaptent à n’importe quelles statistiques d’effacements sur le canal CPL sont utilisés et les performances de schémas coopératifs basés sur ces codes fontaines sur des réseaux linéaires multi-sauts sont étudiés. Enfin des algorithmes permettant de combiner le codage réseau et le codage fontaine pour la topologie particulière des réseaux CPL pour les smart grid sont proposés et évaluésThis PhD dissertation deals with the mitigation of the impact of the Narrowband PowerLine communication (NB-PLC) channel impairments e.g., periodic impulsive noise and narrowband noise, by applying the error/erasure correction coding techniques. After an introduction to the concept of smart grid, the NB-PLC channels are characterized precisely and models that describe these channels are presented. The performance of rank metric codes, simple or concatenated with convolutional codes, that are particularly interesting to combat criss-cross errors on the NB-PLC networks are simulated and compared with Reed- Solomon (already present in several NB-PLC standards) codes performance. Fountain codes that can adapt to any channel erasures statistics are used for the NB-PLC networks and the performance of cooperative schemes based on these fountain codes on linear multi-hop networks are studied. Finally, algorithms to combine the network coding and fountain codes for the particular topology of PLC networks for the smart grid are proposed and evaluated
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Yue, Jing. "Distributed Joint Network-Channel Coding in Multi-Hop Wireless Networks." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15884.
Full textAbstract:
This thesis focuses on the design of distributed joint network-channel coding in multi-hop wireless networks. There are two main research focuses in this thesis, the first one is applying the low-density generator matrix (LDGM) codes to the design of joint network-channel coding, and the second one is designing joint network-channel coding schemes based on fountain codes. To begin with, I apply the LDGM codes to the design of joint network-channel coding. A multiple transmission session model with network code division multiplexing (NCDM) scheme is proposed to remove the inter-session interference at each destination. New code design criteria for the construction of the generator matrix are proposed. Another focus of this thesis is the design of joint network-channel coding using fountain codes. I first propose a distributed network coding (DNC) scheme based on the Raptor codes for wireless sensor networks (WSNs), where a group of sensor nodes, acting as source nodes, communicates with a single sink through other sensor nodes, serving as relay nodes, in a multi-hop fashion. To satisfy the various performance requirements of different source nodes, I propose an unequal error protection (UEP) DNC scheme based on fountain codes to provide arbitrary error protection (i.e., infinite protection levels) to all the source nodes in wireless relay networks (WRNs). Then I investigate the effect from different parameters of the degree distributions. A degree distribution design criteria are proposed for the DNC scheme based on fountain codes over Rayleigh fading channels. In addition to minimizing the overall recovery time among all protection groups, I develop an adaptive UEP DNC scheme to realize adaptive UEP in WRNs. The transmitted data from the source nodes in different protection groups can be recovered successfully under their performance requirements in a shorter time by using the adaptive UEP DNC scheme.
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Apavatjrut, Anya. "De l'usage des codes fontaines dans les réseaux de capteurs multisauts." Phd thesis, INSA de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00708449.
Full textAbstract:
Important sujet de recherche dans les télécommunications contemporaines, les réseaux de capteurs sont des réseaux sans fil constitués de plusieurs nœuds pouvant communiquer entre eux. Chaque capteur est autonome et possède une durée de vie limitée, liée à la taille de sa batterie. Dans ce contexte, l'énergie est une ressource critique qui peut être économisée en minimisant le nombre de paquets émis. De part la nature du médium radio, les données transmises subissent des pertes du canal. La fiabilisation de données dans ce contexte n'est pas simple et devient d'autant plus problématique lorsque la taille de réseau augmente. C'est dans ce contexte que s'inscrit cette thèse qui vise à fournir une technique de fiabilisation des transmissions dans un réseau de capteur. Pour cela, nous proposons de mettre en oeuvre un mécanisme de transmission qui exploite le code fontaine. Ce code est sans rendement et les symboles de redondance sont générés à la volée. Il permet de fiabiliser la transmission avec l'utilisation d'un canal de retour limité. Le code fontaine permet d'alléger le mécanisme de contrôle des transmissions tout en assurant un lien complètement fiable, ce qui permet de réduire la latence et la consommation énergétique d'une transmission. Afin d'optimiser la performance globale du réseau, nous étudions également dans cette thèse le cas où les nœuds sont autorisés à coopérer pour le relayage multi-sauts de paquets destinés à des nœuds distants. Nous montrons dans cette thèse que la technique de codage réseau permet d'introduire de la diversité d'information et ainsi d'améliorer la performance globale de transmissions multi-sauts mono-chemin. Ce résultat a été étendu à la transmission coopérative pour laquelle nous avons à la fois pu exploiter la diversité d'information et la diversité spatiale.
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Ferreira, Paulo Alexandre Ribeiro. "Impacto dos códigos rateless em sistemas de difusão DAB." Doctoral thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/21082.
Full textAbstract:
Doutoramento em Engenharia EletrotécnicaA Rádio Televisão Portuguesa inaugurou a rede de difusão DAB em 1998. Nos anos que se seguiram realizou a sua expansão tendo chegado a cobrir todo o território nacional. Devido a diversos fatores, nomeadamente o preço dos recetores, a rede foi desligada em 2010. Nesta tese mostramos que a tecnologia DAB continua atual, oferecendo grandes vantagens quer aos operadores quer ao público em geral e além disso propõe uma solução tecnológica para a utilização da referida rede DAB. A solução proposta, consiste na difusão de conteúdos multimédia de sinalética e pode ser estendida a qualquer outra rede de difusão, nomeadamente DVB. Para este tipo de conteúdos, propomos o uso de códigos “Fountain” do tipo LT ou Raptor, códigos que conseguem uma grande eficiência e não requerem canal de retorno. No entanto, também mostramos que a existência de um canal de dados alternativo à rede de difusão DAB, mesmo que de baixo débito, permite enviar os dados em falta de forma eficiente e articulada com a rede de difusão DAB. Esta solução permite aumentar a área de cobertura em relação à utilização exclusiva das redes DAB/DVB. No caso Português esta seria uma forma eficiente e comercialmente interessante de tirar partido do espectro livre nas bandas DAB e DVB, nomeadamente para os dispositivos de sinalética e da “Internet of Things”.
The Portuguese Radio Television set up a DAB broadcasting network in 1998. In the years that follow this network was expanded to the whole Portuguese territory. Due to several factors, including the high cost of the receivers, the network was shut down in 2010. In this thesis we show that the DAB technology continues to be a hot topic, presenting many advantages for the operators and consumers. Moreover, we propose a technical solution for an alternative use of the DAB network. The proposed solution consists in the broadcasting of multimedia signage and can be extended to other networks, including the DVB. For this type of contents, we propose the use of Fountain codes like the LT or the Raptor codes that achieve a high efficiency and do not require a feedback channel. However, if an alternate channel exists, even with a low bit-rate, it allows the coverage area to increase when compared to the exclusive use of DAB/DVB networks. In the Portuguese case this would be an efficient and commercially interesting way to take advantage of the free spectrum in DAB and DVB bands, particularly for signage devices and the "Internet of Things".
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Sabir, Essaïd. "MAC protocols design and a cross-layered QoS framework for next generation wireless networks." Phd thesis, Université d'Avignon, 2010. http://tel.archives-ouvertes.fr/tel-00544071.
Full textAbstract:
Ce manuscrit est centré sur la conception, l'amélioration et l'évaluation des protocoles des couches RESEAU, MAC et PHY. En particulier, nous nous focalisons sur la conception de nouveaux protocoles distribués pour une utilisation optimale/améliorée des ressources radio disponibles. Par ailleurs, nous caractérisons les performances des réseaux ad hoc à accès aléatoire au canal en utilisant des paramètres de plusieurs couches avec aptitude de transfert d'information (data forwarding). La majeure partie de nos analyses se base sur le concept d'interaction entre les couches OSI (cross-layer). En effet, cette nouvelle et attractive approche est devenue en peu de temps omniprésente dans le domaine de recherche et développement et dans le domaine industriel. Les métriques de performances qui nous intéressent sont la stabilité des files d'attentes de transfert, le débit, le délai et la consommation d'énergie. Principalement, la compréhension de l'interaction entre les couches MAC/PHY et routage du standard IEEE 802.11e DCF/EDCF, d'une part, et l'interaction entre noeuds en terme d'interférences, d'autre part, constituent le coeur central de notre travail
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Sabir, Essaid. "Conception de Protocoles de la Couche MAC et Modélisation des Réseaux Hétérogènes de Nouvelle Génération." Phd thesis, Université d'Avignon, 2010. http://tel.archives-ouvertes.fr/tel-00538837.
Full textAbstract:
Ce manuscrit est centré sur la conception, l'amélioration et l'évaluation des protocoles des couches RESEAU, MAC et PHY. En particulier, nous nous focalisons sur la conception de nouveaux protocoles distribués pour une utilisation optimale/améliorée des ressources radio disponibles. Par ailleurs, nous caractérisons les performances des réseaux ad hoc à accès aléatoire au canal en utilisant des paramètres de plusieurs couches avec aptitude de transfert d'information (data forwarding). La majeure partie de nos analyses se base sur le concept d'interaction entre les couches OSI (cross-layer). En effet, cette nouvelle et attractive approche est devenue en peu de temps omniprésente dans le domaine de recherche et développement et dans le domaine industriel. Les métriques de performances qui nous intéressent sont la stabilité des files d'attentes de transfert, le débit, le délai et la consommation d'énergie. Principalement, la compréhension de l'interaction entre les couches MAC/PHY et routage du standard IEEE 802.11e DCF/EDCF, d'une part, et l'interaction entre noeuds en terme d'interférences, d'autre part, constituent le coeur central de notre travail.
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Khan, Muhammad Ahsan. "CFD Applications for Wave Energy Conversion Devices (MoonWEC) and Turbulent Fountains for Environmental Fluid Mechanics." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Find full textAbstract:
This thesis is based on two studies that are related to floating wave energy conversion (WEC) devices and turbulent fountains. The ability of the open-source CFD software OpenFOAM® has been studied to simulate these phenomena. The CFD model has been compared with the physical experimental results.
The first study presents a model of a WEC device, called MoonWEC, which is patented by the University of Bologna. The CFD model of the MoonWEC under the action of waves has been simulated using OpenFOAM and the results are promising. The reliability of the CFD model is confirmed by the laboratory experiments, conducted at the University of Bologna, for which a small-scale prototype of the MoonWEC was made from wood and brass.
The second part of the thesis is related to the turbulent fountains which are formed when a heavier source fluid is injected upward into a lighter ambient fluid, or else a lighter source fluid is injected downward into a heavier ambient fluid. For this study, the first case is considered for laboratory experiments and the corresponding CFD model. The vertical releases of the source fluids into a quiescent, uniform ambient fluid, from a circular source, were studied with different densities in the laboratory experiments, conducted at the University of Parma. The CFD model has been set up for these experiments. Favourable results have been observed from the OpenFOAM simulations for the turbulent fountains as well, indicating that it can be a reliable tool for the simulation of such phenomena.
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Lin, Yung-Seng, and 林育聖. "A PAPR Reduction Scheme Using Fountain Codes." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/29124278610733046070.
Full textAbstract:
碩士元智大學
通訊工程學系
99
This thesis mainly discusses that using fountain codes to reduce the peak to average power ratio (PAPR) for OFDM systems. In previous research, the arrangement of the mapping from one fountain codeword to one OFDM symbol has been proven with the PAPR reduction performance similar to the well-known method of selective mapping (SLM). In this thesis, we focus on the arrangement of the mapping from one fountain codeword to n OFDM symbols due to the longer length of the codeword and evaluate its PAPR reduction performance. Besides, the arrangement of the mapping from m fountain codewords, each occupies m/N subcarriers, to m*n OFDM symbols is also considered. Computer simulations show the PAPR reduction improvement for these arrangements.
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OROZCO, VIVIAN. "Trapping Sets in Fountain Codes over Noisy Channels." Thesis, 2009. http://hdl.handle.net/1974/5309.
Full textAbstract:
Fountain codes have demonstrated great results for the binary erasure channel and have already been incorporated into several international standards to recover lost packets at the application layer. These include multimedia broadcast/multicast sessions and digital video broadcasting on global internet-protocol. The rateless property of Fountain codes holds great promise for noisy channels. These are more sophisticated mathematical models representing errors on communications links rather than only erasures. The practical implementation of Fountain codes for these channels, however, is hampered by high decoding cost and delay.
In this work we study trapping sets in Fountain codes over noisy channels and their effect on the decoding process. While trapping sets have received much attention for low-density parity-check (LDPC) codes, to our knowledge they have never been fully explored for Fountain codes. Our study takes into account the different code structure and the dynamic nature of Fountain codes. We show that 'error-free' trapping sets exist for Fountain codes. When the decoder is caught in an error-free trapping set it actually has the correct message estimate, but is unable to detect this is the case. Thus, the decoding process continues, increasing the decoding cost and delay for naught. The decoding process for rateless codes consists of one or more decoding attempts. We show that trapping sets may reappear as part of other trapping sets on subsequent decoding attempts or be defeated by the reception of more symbols. Based on our observations we propose early termination methods that use trapping set detection to obtain improvements in realized rate, latency, and decoding cost for Fountain codes.Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2009-10-29 14:33:06.548
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Wang, Mao-Hua, and 王茂樺. "A Hybrid Coding Scheme that Combines Fountain Codes and Reed-Solomon Codes." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/72724580505627618670.
Full textAbstract:
碩士國立臺灣科技大學
電子工程系
100
Fountain codes have been widely discussed recently. The main characteristic is that the number of encoded packets is not fixed before the transmission. LT code is the first practical type of fountain code; it can achieve great performance and reach low coding and encoding complexities. Since LT codes act well on erasure channel, one might consider whether it can be applied on noisy channel. Because the inter-symbol interference (ISI), the packets may be contaminated. The detrimental effect of error propagation in LT hard decoding may occur. Belief propagation algorithm is a solution to avoid situation like this. However, the simulation results of the bit error rate turn out to be quite high. We need to come up with some method to improve the performance. In this thesis, we create a new type of codes called "Hybrid Fountain Codes" by combining Reed-Solomon codes and LT codes. Under Reed-Solomon codes' correcting ability, errors can be corrected easily and Tanner graph can be updated. By passing information, renewing Tanner graph and removing connections, complexities can be reduced dramatically. The calculation of LLR is an important issue. We have to extract LLR value of both source packets and encoded packets so hard decision can be made. The combination of both hard and soft decision value is also important. Sometimes we have to combine encoded packets' soft decision with source packets' hard decision and vice versa. In this thesis, we derive unified computations for combining hard and soft decisions at the source nodes and encoded nodes. Sometimes the LLR value may be too large to deal with, so the approximate formula is also derived. The main advantage of this scheme is that the bit error rate can approach zero and total iteration times can be lower as compared to LT soft decoding only.
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Chang, Chia-Jung, and 張家榮. "Finite Length Analysis of Generalized Expanding Window Fountain Codes." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/72592165255282742405.
Full textAbstract:
碩士國立臺灣大學
電信工程學研究所
97
Fountain codes are suitable for data transmission over binary erasure channels. When such codes are applied in live broadcast applications, due to the limited bandwidth and delay constraints, it is often convenient to treat the input media stream as a concatenation of short data blocks and to encode each block individually. However, the use of a small block size may result in poor coding efficiency. In this thesis, we introduce an approach to enhance the coding efficiency by encoding over progressively more source bits. Our approach can be considered as a generalization of the expanding window fountain code concept. In addition, we provide an error analysis based on state generating functions. The state generating function is useful both as a performance evaluation tool and as a design criterion for the generalized expanding window codes.
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Tsai, I.-Tse, and 蔡宜澤. "On Fountain Codes for Cooperative Systems UsingVarious Relaying Strategies." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/56842953903610154965.
Full textAbstract:
碩士國立中山大學
通訊工程研究所
100
In wireless communication, multipath fading distorts the phase and the amplitude of received signals and increases error rate, which degrades causes communication quality. Multiple-input-multiple-output (MIMO) techniques can be adopted to achieve diversity gain and reduce error rate. However, MIMO is hard to be implemented in mobile devices due to size limitation. With this regard, cooperative communications are proposed to allow users to cooperate each other’s and then achieve diversity without equipping multiple antennas. On the other hand, if source and relays adopt fixed-rate transmission under time-varying wireless channels, it requires timely feedback about channel-information for transmitters to adjust the rate of channel encoder. To reduce overhead required for aforementioned scheme, we adopt rateless fountain codes in cooperative networks. In recent year, most related studies focus on information-theoretical aspect, but it lacks discussion of practical coding. In our work, we use fountain codes in dual-hop cooperative communication and analyse transmission rate in terms of transmitting time. Fountain code was first proposed as Luby transform codes(LTC) for erasure channels. We combine low-density parity-check code( LDPC code) and LTC in cooperative communication networks, and analyze required transmission time under different cooperative protocols.
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Chiu, Hsin-Liang, and 邱信良. "Fountain Codes for OFDM Multicast Systems with PAPR Reduction Capability." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/22649665133635719117.
Full textAbstract:
碩士國立臺灣大學
電信工程學研究所
97
Recently, fountain codes have got much attention not only in theoretic researches but also in practical applications. Instead of using ARQ (Automatic Retransmit request) methods which may cause large amount of retransmissions for Multicast communication while packet-losses happen among the multicast links, it is more suitable to apply fountain codes for it. In this thesis, we consider an OFDM multicast system which uses fountain codes as packet-level codes to achieve its transmissions. We propose several designs in generating specific fountain codes to solve the inherent high PAPR (Peak-to-Average Power Ratio) problem in OFDM systems. Compared to other usual PAPR reduction methods which need additional side information in the physical layer, our designs require no additional side information in the physical layer. Moreover, the decoding performance of proposed fountain codes maintains almost the same as that of usual fountain codes. Mathematical analyses and simulations verify the excellence of our designs.
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LIAU, Andrew. "Low-Complexity Soliton-like Network Coding for a Resource-Limited Relay." Thesis, 2011. http://hdl.handle.net/1974/6833.
Full textAbstract:
Network coding (NC) is an optimal data dissemination technique where intermediate nodes linearly combine incoming packets. To recover a network-coded message, a sink must use a Gaussian elimination decoder, but this high-complexity decoder may not be acceptable in resource-constrained applications like sensor networks. A good alternative to Gaussian elimination is for the sink to apply the well-known belief propagation (BP) algorithm; however, the performance and complexity of BP decoding is dependent on the statistics of the linearly-combined packets. In this work, we propose two protocols that address this issue by applying fountain coding paradigms to network codes.
For a two-source, single-relay, and single-sink network, named the Y-network, if the relay can network-code incoming packets while maintaining the key properties of the fountain code, then BP decoding can be applied efficiently to recover the original message. Particularly, the sink should see a Soliton-like degree distribution for efficient BP decoding. The first protocol, named Soliton-like rateless coding (SLRC), recognizes that certain encoded packets are essential for BP decoding to perform well. Therefore, the relay protects these important packets by immediately forwarding them to the sink. It can be shown analytically that the proposed scheme is resilient to nodes leaving the transmission session. Through simulations, the SLRC scheme is shown to perform better than buffer-and-forwarding, and the Distributed LT code.
Although SLRC achieves good performance, the degree distribution seen by the sink is non-optimal and assumes that a large number of packets can be buffered, which may not always be possible. Extending SLRC, we propose the Improved Soliton-like Rateless Coding (ISLRC) protocol. Assuming a resource-constrained relay, the available resources at the relay are effciently utilized by performing distribution shaping; packets are intelligently linearly combined. The aggregate degree distribution for the worst case is derived and used in performing an asymptotic error analysis using an AND-OR tree analysis. Simulation results show that even under the worst case scenario of ISLRC, better performance can be achieved compared to SLRC and other existing schemes.Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2011-10-07 21:13:03.862
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Hayajneh, Khaled. "Improving the Left Degree Distribution of Fountain Codes in the Finite-Length Regime." Thesis, 2013. http://hdl.handle.net/1974/8189.
Full textAbstract:
Fountain codes were introduced to provide higher reliability, lower complexities, and
more scalability for networks such as the Internet. In this thesis, we study Luby-
Transform (LT) codes which are the realization of Fountain codes. In the LT
codes, a sparse random factor graph is dynamically generated on both the encoder
and decoder sides of the communications channel. The graph is generated from an
ensemble degree distribution. The LT codes are also known as rateless codes, in the
sense that they can generate potentially limitless codeword symbols from original data
and self-adjust to channels with different erasure probabilities. LT Codes also have a
very low encoding and decoding complexities when comparing with some traditional
block codes, e.g., Reed Solomon (RS) codes and Low-Density-Parity-Check (LDPC)
codes. Therefore, LT Codes are suitable for many different kinds of applications such
as broadcast transmission. LT codes achieve the capacity of the Binary Erasure Channel (BEC) asymptotically and universally. For finite lengths, the search is continued to nd codes closer to the capacity limits at even lower encoding and decoding complexities. Most previous work on single-layer Fountain coding targets the design via the right degree distribution. The left degree distribution of an LT code is left as Poisson to protect the universality. For finite lengths, this is no longer an issue; thus, we focus on the design of better codes for the BEC and noisy channels as well at practical lengths.
We propose two encoding schemes for BEC and noisy channels by shaping the left
degree distribution. Our left degree shaping provides codes outperforming regular LT
code and all other competing schemes in the literature. For instance, at a bit error
rate of 10_{-7} and k = 256, our scheme provides a realized rate of 0.6 which is 23.5% higher than Sorensen et al.'s scheme over BEC. In addition, over noisy channels
our proposed scheme achieves an improvement of 14% in the released rates at k = 100
and 30 Belief Propagation (BP) iterations.Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2013-08-22 19:40:59.885
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Lu, Tung-Lung, and 呂東融. "Design and Performance Evaluation of Fountain Codes in UDP Streaming Environments." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/65073492986595147794.
Full textAbstract:
碩士國立交通大學
資訊學院資訊學程
104
The goals of this thesis are to utilize the network resources optimally and allowed to send real-time data as fast as possible. Excessive network traffic causes network congestion and it leads to packets loss. Transmission Control Protocol (TCP) congestion control avoid this kind of packets loss. However, packets losses could be caused by either network congestion or channel transmission errors. If packet losses are caused by transmission errors, TCP will slow down its sending rate that unnecessarily leads to low throughput. On the other hand, the receiver needs to wait the retransmitted packet when the sent packet is lost. If many packets are lost, it will lead to obvious latency and cause a lot of retransmitted packets, which cannot sustain high throughput. To solve the existing protocol inefficiency problem, we design fountain codes suitable in UDP streaming environments. In our research methods, the blocks of packets can transform them into the algebraic equations. Even if the packets within the block are lost, the receiver can synchronize by the seed number to reconstruct the random number generator matrix, and according to the gauss elimination to decode. The proposed LT encoding uses a characteristic 2 finite field with 256 elements, which can also be called the Galois field GF(2^8). These elements are derived from IETF (Internet Engineering Task Force) RFC 6330. We can use these elements to construct K×N random number matrix. Thus, we can extend K source packets to the N (N>K) encoding packets. If the receiver received the K packets, we could try to recover the K source packets. In the experimental results which indicate that the proposed fountain code in UDP streaming is very helpful in reducing inefficiency in the case of high packet loss rate. The demonstration is designed and implemented by the Network Simulator – NS2. Our results may serve as a basis to facilitate the related future fountain code research.
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Chiu, Hsien-Tzu, and 邱仙姿. "A Framework of Temporal Data Retrieval for Unreliable WSNs Using Distributed Fountain Codes." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/49302743185634816639.
Full textAbstract:
碩士國立清華大學
資訊工程學系
102
Distributed storage coding has been widely applied on data gathering over unreliable wireless sensor networks (WSNs), where it is essential to ensure the data persistence in case of massive sensor failures caused by battery run-out or some physical damage problems surroundings. How to efficiently and scalably disseminate and collect the sensing data over WSNs is a key challenge yet. In this study, assumed that there are K sensor nodes equipped sensing apparatus within N storage sensors, these K numbers of sensors can sense environmental changes and disseminate coded (by Fountain codes) time-series data over WSNs using the simple random walk. That is, each sensor will receive others’ data, randomly select d (which according to the chosen degree distribution) of them, and encode into an encoded data then store it. In this thesis, we employ two types of Fountain codes: Luby Transform (LT) codes and Repairable Fountain (RF) codes to maintain the level of data persistence. In order to perform the Fountain codes over WSNs, the question is to disseminate data in the long range of random walks to preserve the randomness so as to boost the source decoded rate. In other words, the hop count would be long enough such that the decoding process can be perfectly completed using less amount of redundancy (say 10%). In this thesis, a framework of less communication cost is proposed due to the temporal dependency of time-series data. The concept is simple: the complete decoding is not necessary for most of time-series data since the missing portions can be compensated by neighbors if exists. Our framework works as follows. We separate time-series data into two categories. For a given number t, the data corresponding to the numbers divisible by t will be totally recovered with high probability; however, the data corresponding to the other time slots is set as partially recovered. As mentioned, the missing one can be interpolated by the nearby neighboring data through temporal dependency. The proposed framework employs LT codes and RF codes to increase the level reliability. Besides, a mathematical model to estimate the appropriate source decoded rate is proposed to reduce the transmission cost (hop count) while maintaining tolerable level (< 4% normalized root-mean-square error (NRMSE)) of errors as well.
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Hung, Tsung-Kang, and 洪從罡. "The architecture of random linear fountain codes with hybrid coding in multiple Galois fields." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/p3bdh5.
Full text
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Lu, Yi-Pin, and 盧一斌. "Design and Implementation of Real-Time Wireless Video Streaming using Cross-Layer Optimization and Fountain Codes." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/28004601280978447707.
Full textAbstract:
博士國立臺灣大學
電子工程學研究所
104
In order to avoid retransmission latency, Fountain codes, also known as rateless codes, have been widely proposed and applied in the designs for streaming systems. Fountain codes retain the partially decoded information, and continue to receive and decode the coded symbols until the number of accumulated correctly received coded symbols exceeds a pre-determined threshold, and then the complete information sequence can be recovered. This thesis presents a novel solution to cross-layer optimization for fountain code-based video streaming over adaptive multiple-input multiple-output (MIMO)-orthogonal frequency division multiplexing (OFDM) wireless networks. Armed with the adaptive OFDM in combination with the practical channel state information, the transmission throughput can be adjusted in order to improve channel efficiency when fountain codes are used. A resource allocation algorithm is proposed for wireless video streaming using MIMO-OFDM that achieves an improvement in SNR of 8 dB over the conventional approach. When considering the feasibility of hardware implementation, RaptorQ code, the most advanced solution for fountain code, requires that a huge matrix inversion be performed, typically in a dimension of up to 2^{16}. This thesis offers an index-based algorithm that is helpful in improving the online decoding of the RaptorQ decodingii algorithm, employing the same decoding mechanism as the conventional RaptorQ, but reducing the computational complexity from cubic to quadratic. Then, an IC implementation of a configurable RaptorQ decoder in 90 nm technology is presented. This chip achieves an average throughput of 7 Mbps at a power consumption of only 52.7 mW, while supporting compressed video streaming at a quality of up to SDTV (720x480). Furthermore, a low-complexity RaptorQ decoding algorithm is proposed that uses the Sherman-Morrison formula to achieve offine decoding of the RaptorQ decoding algorithm. Compared to the online RaptorQ decoding algorithm, the complexity of the proposed RaptorQ decoding algorithm is only 6.5%. Thus, based on this algorithm, a high performance hardware implementation is designed, and validated using a Xilinx Kintex-7 FPGA board. The throughput of the proposed design reaches 46.5 Mbps, which is more than twice that of previous works, while consuming almost the same power. The thesis finally provides a prototype for how a real-time wireless video streaming system that includes a low latency RaptorQ code will function. Exploiting the high-performance RaptorQ decoder, the FPGA implementation for the proposed RaptorQ decoder is able to fully meet the requirements for the next-generation of wireless video streaming systems. Hence, an FPGA implementation of both a RaptorQ decoder and a MIMO-OFDM receiver for a real-time wireless video streaming system is presented. Together with an RF front-end and a progressive video codec implemented via software, the design, implementation, and validation of a prototype for a high-performance real-time wireless video streaming system are accomplished.
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Peng, Jheng-Bao, and 彭鉦堡. "Broadcast Protocols Using Multipoint Relays And Fountain Codes for FH/TDMA Ad Hoc Networks Under Jamming Environment." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/47455653444654536099.
Full textAbstract:
碩士元智大學
通訊工程學系
99
This thesis mainly discusses the protocols for broadcasting through multihop multipoint relays in wireless ad hoc networks. A base station broadcasts packets, which are first fountain encoded, downlink to all ad hoc nodes through multipoint relays. For simplicity, the relays transmit their packets according to the schedule of FH/TDMA. We assume two jamming cases which cause packet damaged. One is block jamming and the other is bit jamming. Besides the well-known flooding protocol and the optimized link state routing (OLSR) protocol under block jamming, we propose a weighted link state routing protocol. Compared with the flooding protocol, the proposed protocol can effectively decrease the total number of retransmitted packets sent by the relays in the network. Compared with the OLSR protocol, the proposed protocol can effectively decrease the retransmission delay in average for all nodes in the network. Under bit jamming, we propose the concept of virtual link to achieve higher resisting ability to jamming and hence lower number of retransmitted packets in the network. Simulation results verify our proposed ideas which provide good performance in the wireless ad hoc network.
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Al-Awami, Louai. "Distributed Data Storage System for Data Survivability in Wireless Sensor Networks." Thesis, 2013. http://hdl.handle.net/1974/8403.
Full textAbstract:
Wireless Sensor Networks (WSNs) that use tiny wireless devices capable of communicating,
processing, and sensing promise to have applications in virtually all fields.
Smart homes and smart cities are just few of the examples that WSNs can enable.
Despite their potential, WSNs suffer from reliability and energy limitations.
In this study, we address the problem of designing Distributed Data Storage Systems
(DDSSs) for WSNs using decentralized erasure codes. A unique aspect of WSNs
is that their data is inherently decentralized. This calls for a decentralized mechanism
for encoding and decoding. We propose a distributed data storage framework
to increase data survivability in WSNs. The framework utilizes Decentralized Erasure
Codes for Data Survivability (DEC-DS) which allow for determining the amount
of redundancy required in both hardware and data to allow sensed data to survive
failures in the network.
To address the energy limitations, we show two approaches to implement the
proposed solution in an energy efficient manner. The two approaches employ Random
Linear Network Coding (RLNC) to exploit coding opportunities in order to
save energy and in turn prolong network life. A routing based scheme, called DEC
Encode-and-Forward (DEC-EaF), applies to networks with routing capability, while
the second, DEC Encode-and-Disseminate (DEC-EaD), uses a variation of random
walk to build the target code in a decentralized fashion. We also introduce a new
decentralized approach to implement Luby Transform (LT)-Codes based DDSSs. The
scheme is called Decentralized Robust Soliton Storage (DRSS) and it operates in a
decentralized fashion and requires no coordination between sensor nodes.
The schemes are tested through extensive simulations to evaluate their performance.
We also compare the proposed schemes to similar schemes in the literature.
The comparison considers energy efficiency as well as coding related aspects. Using
the proposed schemes can greatly improve the reliability of WSNs especially under
harsh working conditions.Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2013-09-30 22:43:04.509
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BENACEM, Lucien. "Cooperative DVB-H: Raptor-Network Coding Protocols for Reliable and Energy Efficient Multimedia Communications." Thesis, 2010. http://hdl.handle.net/1974/5955.
Full textAbstract:
Reliable and energy-efficient delivery of multimedia to mobile terminals in dynamic networks is a very challenging problem. In this thesis, we focus on a cooperative extension to the Digital Video Broadcasting – Handheld (DVB-H) standard, forming a cooperative broadcast network whereby terminal-to-terminal cooperation creates a distributed form of multi-input-multi-output (MIMO) that supplements existing fixed network infrastructure.
First, we develop a novel and computationally-efficient hierarchical Markov model that is able to accurately perform a cross-layer packet error mapping between the physical and transport layers of the DVB-H/IPDC (IP DataCast) protocol stack. We then construct a discrete-event simulator in MATLAB® that incorporates all of the necessary modules to conduct dynamic multiterminal network simulations. Next, the convergence of cooperative wireless communication, Raptor application layer forward error correction (AL-FEC) and Network Coding (NC) is examined. Originally proposed for broadcasting over the Internet, the application of Raptor codes to wireless cooperative communications networks has been limited to date, but they have been mandated for use in DVB-H. Network coding is used to reduce energy consumption by opportunistically recombining and rebroadcasting required combinations of packets. Two novel coding-enabled cooperative relaying protocols are developed for multicast and multiple unicast file distribution scenarios that are transparent, fully distributed, and backwards compatible with today's systems. Our protocols are able to exploit several different forms of diversity inherent to modern wireless networks, including spatial diversity, radio interface diversity, and symbol diversity. Extensive simulations show that our protocols simultaneously achieve breakthroughs in network energy efficiency and reliability for different terminal classes and densities, allowing greatly improved user experiences.Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2010-08-03 19:45:54.943
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Yang, Ding-Da, and 楊定達. "A Study on Designing Unequal error Protected Fountain coeds." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/69682623917058965019.
Full textAbstract:
碩士元智大學
通訊工程學系
97
This thesis mainly concerns about the state-of-art methods on unequal error protected (UEP) fountain codes. The basic fountain codes such as random linear fountain codes, Luby Transform (LT) codes and Raptor codes are first introduced. Next, four existing UEP fountain codes use sliding windows, block duplication, priorities, expanding windows are examined. Besides we have made performance comparison among these methods, we propose some intuitive solutions to create more UEP classes on the sliding windows and priorities cases. In order to improve the failure rates of these codes, Raptor codes which integrates LDPC codes as outer codes and these UEP fountain codes as inner codes are also discussed in this thesis.
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Lai, Yu-Hsun, and 賴煜勛. "Fountain Code Implementation in Compressed sensing for UDP streaming applications." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/466cag.
Full textAbstract:
碩士國立交通大學
電子研究所
107
Deployments of video streaming applications in wireless mesh networks increase in recent years. However, the packet loss is inevitable in wireless channels. TCP applies retransmissions once a packet is lost, which makes TCP not suitable for multimedia communication. Unlike TCP, UDP does not require retransmission. It retains a high/constant transmission rate in a channel of high loss rate; however, the transmission quality is not guaranteed. The fountain code is a forward error correction method which guarantees to recover data as long as a sufficient amount of data is received. In this thesis, we implement a fountain code scheme on top of UDP for streaming applications. Due to the low throughput of a software implementation, we implement a fountain code hardware decoder in 65nm process. This decoder achieves 488.2MB/s under 500 Mhz. Under this fountain code scheme, a throughput higher than that of TCP in a high packet loss rate channel can be achieved. Since a fountain code decoder starts the decoding process only when enough codewords are received. This may cause video delay. We proposed a fountain code scheme compressed sensing algorithm that can start the decoding process even when there are not enough received codewords. In this way, it can be regarded as a scalable video coding scheme.
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Chen, Chien-Hung, and 陳建宏. "Secure Multipath Routing Using Fountain Code for Mobile Ad-Hoc Networks." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/63041086234400731250.
Full textAbstract:
碩士國立宜蘭大學
資訊工程研究所碩士班
99
Due to the rapid development of wireless network technologies such as Bluetooth, ZigBee, Wi-Fi, WiMAX, to name a few MANETs (Mobile Ad hoc Networks) have become the networks of choice for various types of applications, including military applications, emergency preparedness and responses, crisis management, to name a few. With these advantages come some challenges, particularly from a data routing and security standpoint. In a MANET, information exchange between nodes can happen without the need of a centralized server or human operator, assuming that nodes cooperate with each other for routing. With this requirement in mind, the presence of malicious nodes in routing operations may cause serious security concerns. Due to these issues associated with cooperative routing, providing a complete message security in MANETs is still a challenge. We propose a novel trust-based multipath routing scheme for MANETs (so-called Fountain Trusted-based Multipath AODV routing protocol - FTMAODV) which uses the fountain code to build a trusted and secure path to transmit the message from source to destination. Simulation experiments show that FTMAODV outperforms AODV and AOMDV in terms of end-to-end delay, packet delivery ratio, and throughput, chosen as performance metrics.
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"Digital Fountain for Multi-node Aggregation of Data in Blockchains." Master's thesis, 2018. http://hdl.handle.net/2286/R.I.51720.
Full textAbstract:
abstract: Blockchain scalability is one of the issues that concerns its current adopters. The current popular blockchains have initially been designed with imperfections that in- troduce fundamental bottlenecks which limit their ability to have a higher throughput and a lower latency.
One of the major bottlenecks for existing blockchain technologies is fast block propagation. A faster block propagation enables a miner to reach a majority of the network within a time constraint and therefore leading to a lower orphan rate and better profitability. In order to attain a throughput that could compete with the current state of the art transaction processing, while also keeping the block intervals same as today, a 24.3 Gigabyte block will be required every 10 minutes with an average transaction size of 500 bytes, which translates to 48600000 transactions every 10 minutes or about 81000 transactions per second.
In order to synchronize such large blocks faster across the network while maintain- ing consensus by keeping the orphan rate below 50%, the thesis proposes to aggregate partial block data from multiple nodes using digital fountain codes. The advantages of using a fountain code is that all connected peers can send part of data in an encoded form. When the receiving peer has enough data, it then decodes the information to reconstruct the block. Along with them sending only part information, the data can be relayed over UDP, instead of TCP, improving upon the speed of propagation in the current blockchains. Fountain codes applied in this research are Raptor codes, which allow construction of infinite decoding symbols. The research, when applied to blockchains, increases success rate of block delivery on decode failures.Dissertation/Thesis
Masters Thesis Computer Science 2018
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Guo, Yi-Shiuan, and 郭憶萱. "Design of a Fountain-Code-Based Error Control Scheme for On-Demand Streaming." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/46049047838387402587.
Full textAbstract:
碩士國立高雄應用科技大學
資訊管理系
97
In wireless network environments, there exist many factors that may interference the transmission of data. How to reduce the error rate in wireless transmission is an important design issue for wireless applications. In this paper, we focus on the error control problem for on-demand streaming. There are two types of error control schemes: automatic repeat request (ARQ) or forward error correction (FEC). The use of ARQ requires the retransmission of data, which causes extra overhead for the server and the network and may violate the real-time requirement of streaming data. On the other hand, traditional FEC schemes employ Reed-Solomon Codes, which has high coding efficiency and computational complexity. In view of this, in this paper, we proposed a novel approach that combined Multiplexed Harmonic Broadcasting and digital fountain codes to cope with the error control problem. The proposed scheme can actually compute the maximum initial waiting time required for users to obtain jitter-free smooth video streaming. Our simulation results show that the proposed error control scheme performs well in different network conditions as compared to traditional FEC error control scheme.
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HSU, TSAI-CHEN, and 許在鎮. "Optimal Resource Allocation in Fountain Coded Cognitive Radio Networks with Energy Harvesting Secondary Users." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/49681586155052485971.
Full textAbstract:
碩士國立中山大學
通訊工程研究所
103
In recent years,people rely on mobile communication in their daily life due to rapid development of wireless communications, which leads to growing demand of wireless data transmission.With this regard,spectrum resources become more and more scarce and expensive.With the development of electronic devices,mobile devices have more and more powerful functions, leading to increase on energy consumption.Therefore, RF energy harvesting that converts RF signals into electricity has been investigated to extend the battery lifetime of smart devices.Scholars have suggested that it can be converted to electromagnetic energy reception.This paper considers cognitive radio networks with one pair of primary users(PU) and multiple pairs of secondary users(SU), where second transmitters harvest energy from signal transmitted by PU.One the other hand, SU acts as a relay to boost primary transmission.THus, SU can be allocated with longer time-period to transmit itsown signal.We investigate optimal resource allocation at secondary user to maximize SU''s throughput subject to guaranteeing success of primary transmission.Due to we have multiple SUs, we will choose one optimal SU based on the maximal throughput according to the optimal resource allocation of respective SU.In order to enhance spectrum efficiency we adopt fountain coding to ecnode primary message at both PU and SU.This thesis aims to optimize the resource allocation of SUs in term of maximal throughput under the premise of successful primary transmission.Give the choice of SU, we derive close-form solution of optimal resource allocation maximum throughput.Finally, it shows through simulations that throughput of secondary transmission increases with the number of SU.
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Chen, Yu Heng, and 陳鈺衡. "The Decoding Probability Model Estimation of Fountain Code Over P2P Streaming System and Its Application." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/64336610956082345191.
Full textAbstract:
碩士國立清華大學
電機工程學系
100
ECC (Error-Correcting Codes) is used to recover loss data due to error in network data transmission. The traditional ECC has fixed code rate, the code rate will affect the ability of error correction, if channel condition is so bad that the quantity of data loss is too large to recover, the overall system decoding performance will drop quickly due to error propagation in P2P streaming system. In the thesis, we use fountain code combine with P2P system, fountain code doesn’t have the fixed code rate, so there is no problems of error checking and correction. We proposed a decoding distribution which is an approximation to statistic results for fountain code, and we put the distribution’s information into our distributed decoding probability predicted model which considers error propagation. Furthermore, we can do peer selection by using the predicted decoding probability when the upload bandwidth is not enough. Our experimental results show that the proposed predicted model has high accuracy, and the overall system decoding probability also increases after our peer selection method.
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Luus, Francois Pierre Sarel. "Joint source-channel-network coding in wireless mesh networks with temporal reuse." Diss., 2011. http://hdl.handle.net/2263/28903.
Full textAbstract:
Technological innovation that empowers tiny low-cost transceivers to operate with a high degree of utilisation efficiency in multihop wireless mesh networks is contributed in this dissertation. Transmission scheduling and joint source-channel-network coding are two of the main aspects that are addressed. This work focuses on integrating recent enhancements such as wireless network coding and temporal reuse into a cross-layer optimisation framework, and to design a joint coding scheme that allows for space-optimal transceiver implementations. Link-assigned transmission schedules with timeslot reuse by multiple links in both the space and time domains are investigated for quasi-stationary multihop wireless mesh networks with both rate and power adaptivity. Specifically, predefined cross-layer optimised schedules with proportionally fair end-to-end flow rates and network coding capability are constructed for networks operating under the physical interference model with single-path minimum hop routing. Extending transmission rights in a link-assigned schedule allows for network coding and temporal reuse, which increases timeslot usage efficiency when a scheduled link experiences packet depletion. The schedules that suffer from packet depletion are characterised and a generic temporal reuse-aware achievable rate region is derived. Extensive computational experiments show improved schedule capacity, quality of service, power efficiency and benefit from opportunistic bidirectional network coding accrued with schedules optimised in the proposed temporal reuse-aware convex capacity region. The application of joint source-channel coding, based on fountain codes, in the broadcast timeslot of wireless two-way network coding is also investigated. A computationally efficient subroutine is contributed to the implementation of the fountain compressor, and an error analysis is done. Motivated to develop a true joint source-channel-network code that compresses, adds robustness against channel noise and network codes two packets on a single bipartite graph and iteratively decodes the intended packet on the same Tanner graph, an adaptation of the fountain compressor is presented. The proposed code is shown to outperform a separated joint source-channel and network code in high source entropy and high channel noise regions, in anticipated support of dense networks that employ intelligent signalling. AFRIKAANS : Tegnologiese innovasie wat klein lae-koste kommunikasie toestelle bemagtig om met ’n hoë mate van benuttings doeltreffendheid te werk word bygedra in hierdie proefskrif. Transmissie-skedulering en gesamentlike bron-kanaal-netwerk kodering is twee van die belangrike aspekte wat aangespreek word. Hierdie werk fokus op die integrasie van onlangse verbeteringe soos draadlose netwerk kodering en temporêre herwinning in ’n tussen-laag optimaliserings raamwerk, en om ’n gesamentlike kodering skema te ontwerp wat voorsiening maak vir spasie-optimale toestel implementerings. Skakel-toegekende transmissie skedules met tydgleuf herwinning deur veelvuldige skakels in beide die ruimte en tyd domeine word ondersoek vir kwasi-stilstaande, veelvuldige-sprong draadlose rooster netwerke met beide transmissie-spoed en krag aanpassings. Om spesifiek te wees, word vooraf bepaalde tussen-laag geoptimiseerde skedules met verhoudings-regverdige punt-tot-punt vloei tempo’s en netwerk kodering vermoë saamgestel vir netwerke wat bedryf word onder die fisiese inmengings-model met enkel-pad minimale sprong roetering. Die uitbreiding van transmissie-regte in ’n skakel-toegekende skedule maak voorsiening vir netwerk kodering en temporêre herwinning, wat tydgleuf gebruiks-doeltreffendheid verhoog wanneer ’n geskeduleerde skakel pakkie-uitputting ervaar. Die skedules wat ly aan pakkie-uitputting word gekenmerk en ’n generiese temporêre herwinnings-bewuste haalbare transmissie-spoed gebied word afgelei. Omvattende berekenings-eksperimente toon verbeterde skedulerings kapasiteit, diensgehalte, krag doeltreffendheid asook verbeterde voordeel wat getrek word uit opportunistiese tweerigting netwerk kodering met die skedules wat geoptimiseer word in die temporêre herwinnings-bewuste konvekse transmissie-spoed gebied. Die toepassing van gesamentlike bron-kanaal kodering, gebaseer op fontein kodes, in die uitsaai-tydgleuf van draadlose tweerigting netwerk kodering word ook ondersoek. ’n Berekenings-effektiewe subroetine word bygedra in die implementering van die fontein kompressor, en ’n foutanalise word gedoen. Gemotiveer om ’n ware gesamentlike bron-kanaal-netwerk kode te ontwikkel, wat robuustheid byvoeg teen kanaal geraas en twee pakkies netwerk kodeer op ’n enkele bipartiete grafiek en die beoogde pakkie iteratief dekodeer op dieselfde Tanner grafiek, word ’n aanpassing van die fontein kompressor aangebied. Dit word getoon dat die voorgestelde kode ’n geskeide gesamentlike bron-kanaal en netwerk kode in hoë bron-entropie en ho¨e kanaal-geraas gebiede oortref in verwagte ondersteuning van digte netwerke wat van intelligente sein-metodes gebruik maak.Dissertation (MEng)--University of Pretoria, 2011.
Electrical, Electronic and Computer Engineering
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