Tesi sul tema "Error Protection"
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1
Marka, Madhavi. "Object-based unequal error protection". Thesis, Mississippi State : Mississippi State University, 2002. http://library.msstate.edu/etd/show.asp?etd=etd-06242002-152555.
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Ammar, Bassem AbuBakr. "Error protection and security for data transmission". Thesis, Lancaster University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421640.
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Deetzen, Neele von. "Modern coding schemes for unequal error protection". Aachen Shaker, 2009. http://d-nb.info/993093108/04.
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Yang, Guanghua. "Adaptive unequal error protection for wireless video transmissions". Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37153791Bib.
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Charbit, Gilles Gerald. "Error protection techniques for frequency-hopping Spread-Spectrum". Thesis, Lancaster University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238955.
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Yang, Guanghua, e 楊光華. "Adaptive unequal error protection for wireless video transmissions". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37153791.
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Yu, Kevin C. (Kevin Cherng-Kai). "Unequal error protection codes based on trellis shaping". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36034.
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Iqbal, Muhammad Imran. "On Perception-Based Error Protection for Mobile Multimedia". Doctoral thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00530.
Testo completoAbstract (sommario):
Representation of multimedia requires large amounts of data. Therefore, multimedia source signals are compressed to reduce the data rate that would otherwise be required for its transmission. However, compression renders multimedia data more vulnerable to transmission errors. Therefore, error protection is needed when transmitting multimedia to mobile users over wireless channels. As channel coding adds parity symbols to the data for error protection, which in turn increases transmission data rate, efficient utilization of this added parity budget becomes a key for insuring quality of service for mobile multimedia. Computing the optimal parity allocation among packets of a multimedia stream may not be possible in realtime due to the huge number of ways the parity can be assigned to these packets. Therefore, it is important to design powerful error protection schemes while imposing low computational and memory demands on the system. This is particularly true for systems having limited resources, such as mobile handheld devices. Given that human beings are the final judges on the quality of multimedia services, it will also be beneficial to use perceptual quality metrics that correlate well with human perception when evaluating different error protection schemes. In this work, we have considered the above aspects when designing error protection for mobile multimedia: Providing near optimal performance while keeping complexity low; designing and evaluating of error protection schemes based on perceptual quality metrics. The thesis is divided into five parts. In the first part, region of interest (ROI) identification, coding and advantages of ROI coding are investigated. In addition, a framework is proposed for using ROI coding in wireless imaging. The second part provides a number of unequal error protection (UEP) schemes for wireless imaging ranging from very simple and less efficient equal error protection to very complex yet optimal error protection. The proposed error protection schemes provide an excellent trade-off between performance and omplexity. In the third part, a framework for perception-based error protection of images and video streams is proposed. This framework is based on the fact that the human visual system is more sensitive to quality degradation in the ROI compared to the background. The proposed error protection scheme provides excellent performance. Part four deals with realtime systems and/or systems having limited memory and processing resources. Specifically, an UEP is proposed for wireless imaging systems which provides near optimal performance and puts very low processing/memory demands on the systems. Finally, in the fifth part, optimal UEP is analyzed. Based on the analysis, optimal UEP is modeled using several mathematical models. Each of the considered models is evaluated for its fitness in providing error protection. The simulation results show that most of the investigated models give excellent performance.
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Bredtmann, Oliver [Verfasser]. "Unequal Error Protection Coding of Quantized Data / Oliver Bredtmann". Aachen : Shaker, 2011. http://d-nb.info/1098039947/34.
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Sankaranarayanan, Sundararajan, Aleksandar Cvetković e Bane Vasić. "UNEQUAL ERROR PROTECTION FOR JOINT SOURCE-CHANNEL CODING SCHEMES". International Foundation for Telemetering, 2003. http://hdl.handle.net/10150/607481.
Testo completoAbstract (sommario):
International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, NevadaA joint source-channel coding scheme (JSCCS) used in applications, like sending images, voice, music etc. over internet/ wireless networks, involves source coding to compress the information and channel coding to detect/ correct errors, introduced by the channel. In this paper, we investigate the unequal error protection (UEP) capability of a class of low-density parity-check (LDPC) codes in a JSCCS. This class of irregular LDPC codes is constructed from cyclic difference families (CDFs).
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Deetzen, Neele von [Verfasser]. "Modern Coding Schemes for Unequal Error Protection / Neele von Deetzen". Aachen : Shaker, 2009. http://d-nb.info/1126378380/34.
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Boyle, Kevin P. (Kevin Patrick). "Rateless and rateless unequal error protection codes for Gaussian channels". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42251.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 141-143).
In this thesis we examine two different rateless codes and create a rateless unequal error protection code, all for the additive white Gaussian noise (AWGN) channel. The two rateless codes are examined through both analysis and simulation with the hope of developing a better understanding of how the codes will perform and pushing the codes further toward implementation. After analyzing and simulating the rateless codes by themselves, we compare using a rateless code to two different forms of hybrid automatic repeat request (HARQ), namely Chase combining HARQ and incremental redundancy HARQ. We find that the rateless codes compare favorably to both forms of HARQ. In addition, we develop a code that has both rateless and unequal error protection (UEP) properties. A rateless code adapts to the quality of the channel and achieves capacity but all of the information bits are decoded at the same time and thus the bitstream cannot be prioritized. In addition, if only a finite number of retransmissions is allowed, the range of available rates that a rateless code can provide is limited. In contrast, a UEP code provides a prioritization of the bitstream, and an arbitrary range of rates but does not achieve capacity. The rateless UEP code, or RUEP code for short, provides the prioritization of a bitstream that UEP provides, and also adapts to the quality of the channel as a rateless code does. The RUEP code provides bitstream prioritization while being more efficient than a traditional UEP code and is capacity achieving for some channel realizations. In addition, the RUEP code provides a larger range of available rates than a rateless code when only a finite number of retransmissions is allowed.
by Kevin P. Boyle.
S.M.
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Hassan, Khaled Shawky [Verfasser]. "Unequal Error Protection Adaptive Modulation in Multicarrier Systems / Khaled Shawky Hassan". Aachen : Shaker, 2011. http://d-nb.info/1071529242/34.
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Charfi, Youssef. "Efficient error protection for image and video transmission over noisy channels". [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971463328.
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Zhu, Chuan. "Joint source-channel decoding and unequal error protection aided video transmission". Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/400650/.
Testo completoAbstract (sommario):
Shannon’s source and channel-coding separation theorem has been the basic philosophy followed by most state-of-the-art wireless transceivers, where all source signals are assumed to have the same importance and are protected equally by the channel encoder. However, due to its assumption of using idealized Gaussian channels, potentially infinite encoding/decoding delay as well as complexity, Shannon’s source and channel-coding theorem is not strictly applicable in practical wireless scenarios. This is because it is almost impossible to remove all the redundancy of the video source, therefore there exits a certain amount of residual correlation. Moreover, reallife applications are often required to transmit source signals associated with unequal importance, such as the base-layer and enhancement-layer of layered video codecs. Hence joint source-channel coding (JSCC) was proposed for wireless scenarios by jointly exploiting the residual redundancy of the video source and the intentionally imposed redundancy of unequal error protection (UEP) techniques. A video codec suitable for lossless video compression and iterative source-channel decoding (ISCD) is proposed by further developing the Markov random field (MRF) soft source decoder for the transmission of video sequences, rather than still video pictures. More explicitly, we used low complexity frame-differencing (FD) for removing the temporal-domain inter-frame redundancy. The low-complexity FD technique does not rely on power-thirsty motion-vector-based motion-compensation and as its other benefit, it does not require the transmission of motion vectors. However, this results in more residual redundancy than the more complex motion-vector based motion-compensation. Furthermore, variable-length code (VrLC) is used for removing the residual spatial redundancy of the FD signal, while exploiting the correlations amongst the FD pixels within the current frame with the aid of our MRF model based soft-in-soft-out (SISO) module. By adopting the MRF for modelling of the video pixels, we can infer maximum a posteriori (MAP) image estimates from the 2-D spatial redundancy between the video pixels, while simpler models like the Markov chain can only explore the 1-D spatial redundancy. Although the estimation of the MRF parameters is a challenge compared to the 1-D Markov models, we conceived novel extrinsic information transfer (EXIT)-chart-based estimation methods, which are shown to be effective. Moreover, a novel three-stage ISCD structure is proposed, which outperforms the two-stage architecture. Furthermore, we examined the convergence of the three-stage iterative decoding process using 3D EXIT charts. The performance of our system operating both with and without FD is compared to our benchmarker schemes. In support of inter-layer forward error correction (IL-FEC) coded layered video transmission, we conceived an adaptive truncated HARQ (ATHARQ) scheme for minimizing the video distortion under the constraint of a given total number of transmission time slots. More specifically, we investigated the merits of IL-FEC schemes in the context of truncated HARQ (THARQ) transmission schemes, where the packet scheduling arrangements were carefully designed for exploiting the specific characteristics of each IL-FEC coded packet. Furthermore, we developed a method of on-line optimization for our IL-ATHARQ transmission scheme, in order to find the most appropriate FEC code rate distribution among the video layers that reduced the video distortion. Type-I HARQ relying on Convolutional Codes (CC) was used for simplicity, because our focus was on the design of the scheduling schemes. The performance of our IL-ATHARQ scheme as well as of the rate-optimized IL-ATHARQ scheme using a RSC codec were compared to the benchmarkers using different video sequences, followed by characterizing both the effects of the delay as well as of the channel quality prediction errors on the attainable system performance. Finally, we conceived an UEP scheme for layered video transmission in the downlink of a visible light communication system, explicitly, we proposed a hierarchical colour-shift keying (HCSK) modulation scheme based on the standardized colourshift keying (CSK), which is capable of conveying inter-dependent layers of video signals. More specifically, we proposed the Type I and Type II HCSK arrangements, which can be flexibly configured by according to the channel quality, video quality, etc., where the Type II constellation allows us to use a wider range of FERs for the higher layers upon varying the constellation-shaping parameter dl. Our simulation results show that Type II HCSK provides a high grade of flexibility in terms of both its system configuration and optimization. Furthermore, we provided a detailed design example for the employment of HCSK transmitting scalable video sources with the aid of a RSC code. An optimisation method was conceived in order to enhance the UEP and to improve the quality of the received video. The performance of our optimised M-HCSK-RSC video transmission system using different HCSK constellation sizes was compared to the relevant benchmarker schemes using different video sequences.
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Natu, Ambarish Shrikrishna Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Error resilience in JPEG2000". Awarded by:University of New South Wales. Electrical Engineering and Telecommunications, 2003. http://handle.unsw.edu.au/1959.4/18835.
Testo completoAbstract (sommario):
The rapid growth of wireless communication and widespread access to information has resulted in a strong demand for robust transmission of compressed images over wireless channels. The challenge of robust transmission is to protect the compressed image data against loss, in such a way as to maximize the received image quality. This thesis addresses this problem and provides an investigation of a forward error correction (FEC) technique that has been evaluated in the context of the emerging JPEG2000 standard. Not much effort has been made in the JPEG2000 project regarding error resilience. The only techniques standardized are based on insertion of marker codes in the code-stream, which may be used to restore high-level synchronization between the decoder and the code-stream. This helps to localize error and prevent it from propagating through the entire code-stream. Once synchronization is achieved, additional tools aim to exploit as much of the remaining data as possible. Although these techniques help, they cannot recover lost data. FEC adds redundancy into the bit-stream, in exchange for increased robustness to errors. We investigate unequal protection schemes for JPEG2000 by applying different levels of protection to different quality layers in the code-stream. More particularly, the results reported in this thesis provide guidance concerning the selection of JPEG2000 coding parameters and appropriate combinations of Reed-Solomon (RS) codes for typical wireless bit error rates. We find that unequal protection schemes together with the use of resynchronization makers and some additional tools can significantly improve the image quality in deteriorating channel conditions. The proposed channel coding scheme is easily incorporated into the existing JPEG2000 code-stream structure and experimental results clearly demonstrate the viability of our approach
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Zhou, Xiang-Yu (Xiang-Yu Leo). "Error-suppression by energy-gap protection for quantum computation in open systems". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92671.
Testo completoAbstract (sommario):
Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2014.Missing pages 43 and 44. Cataloged from PDF version of thesis.
Includes bibliographical references (pages 57-58).
Adiabatic Quantum Computation, while attractive due to its "hands-off" approach and intrinsic tolerance of noise, has not been shown to be fully fault-tolerant in a satisfying manner. The protection of the evolution from noise and decoherence through the use of an energy penalty, recently proposed as a method to suppress error in adiabatic algorithms, is also appealing due to its passiveness. In this thesis, we first introduce the background on quantum computation, and discuss existing efforts towards fault-tolerant computation, specifically in the adiabatic model. Subsequently, we will prove a general result concerning the utility of energy-gap protection in generic (not necessarily adiabatic) quantum evolution in open system, and provides analytic bounds on the necessary energy penalty magnitude to achieve good protection. Evidence from numerical simulation is also given to demonstrate the practical usefulness of energy-gap protection for fault-tolerant quantum computation in open systems.
by Xiang-Yu (Leo) Zhou.
S.B.
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Tumula, V. K. Chaitanya. "HARQ Systems: Resource Allocation, Feedback Error Protection, and Bits-to-Symbol Mappings". Doctoral thesis, Linköpings universitet, Kommunikationssystem, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-96021.
Testo completoAbstract (sommario):
Reliability of data transmission is a fundamental problem in wireless communications. Fading in wireless channels causes the signal strength to vary at the receiver and this results in loss of data packets. To improve the reliability, automatic repeat request (ARQ) schemes were introduced. However these ARQ schemes suffer from a reduction in the throughput. To address the throughput reduction, conventional ARQ schemes were combined with forward error correction (FEC) schemes to develop hybrid-ARQ (HARQ) schemes. For improving the reliability of data transmission, HARQ schemes are included in the present wireless standards like LTE, LTE-Advanced and WiMAX. Conventional HARQ systems use the same transmission power and the same number of channel uses in different ARQ rounds. However this is not optimal in terms of minimizing the average transmit power or the average energy spent for successful transmission of a data packet. We address this issue in the first part of the dissertation, where we consider optimal resource allocation in HARQ systems with a limit on the maximum number of allowed transmissions for a data packet. Specifically, we consider the problem of minimizing the packet drop probability (PDP) under an average transmit power constraint or equivalently minimizing the average transmit power under a fixed PDP constraint. We consider both incremental redundancy (IR)-based and Chase combining (CC)-based HARQ systems in our work. For an IR-HARQ system, for the special case of two allowed transmissions for each packet, we provide a solution for the optimal number of channel uses and the optimal power to be used in each ARQ round. For a CC-HARQ system, we solve the problem of optimal power allocation in i.i.d. Rayleigh fading channels as well as correlated Rayleigh fading channels. For the CC-HARQ case, we also provide a low complexity geometric programming (GP) solution using an approximation of the outage probability expression. HARQ systems conventionally use one bit acknowledgement (ACK)/negative ACK (NACK) feedback from the receiver to the transmitter. In the 3GPP-LTE systems, one method for sending these HARQ acknowledgement bits is to jointly code them with the other control signaling information using a specified Reed-Muller code consisting of 20 coded bits. Even though the resources used for sending this control signaling information can inherently provide a diversity gain, the Reed-Muller code with such a short block size is not good at extracting all of the available diversity. To address this issue, in the second part of this dissertation, we propose two new methods: i) based on complex-field coding (CFC), and ii) using repetition across frequency bands, to extract the inherent diversity available in the channel resources and improve the error protection for the HARQ acknowledgement bits along with the other control signaling information. In the second part of the dissertation, we also propose a new signal space diversity (SSD) scheme, which results in transmit signals having constant envelope (CE). The proposed CE-SSD scheme results in a better overall power efficiency due to the reduced back-off requirements on the radio frequency power amplifier. Moreover, the proposed CE-SSD technique can be useful for application scenarios involving transmission of small number of information bits, such as in the case of control signaling information transmission. In conventional HARQ systems, during the retransmission phase, the channel resources are exclusively used for the retransmitted data packet. This is not optimal in terms of efficient resource utilization. For efficient utilization of channel resources during the retransmissions, a superposition coding (SPC) based HARQ scheme was proposed in the literature. In an SPC based HARQ system, an erroneous packet is transmitted together with a new data packet by superposition in the Euclidean space. In the final part of this dissertation, we study performance of different bits-to-symbol mappings for such an SPC based HARQ system.
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Sandberg, Sara. "Low-density parity-check codes : unequal error protection and reduction of clipping effects /". Luleå, 2009. http://pure.ltu.se/ws/fbspretrieve/2546109.
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Rahnavard, Nazanin. "Coding for wireless ad-hoc and sensor networks unequal error protection and efficient data broadcasting /". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/26673.
Testo completoAbstract (sommario):
Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008.Committee Chair: Professor Faramarz Fekri; Committee Member: Professor Christopher Heil; Committee Member: Professor Ian F. Akyildiz; Committee Member: Professor James H. McClellan; Committee Member: Professor Steven W. McLaughlin. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Philippot, Luc. "Parameter estimation and error estimation for line fault location and distance protection in power transmission systems". Doctoral thesis, Universite Libre de Bruxelles, 1995. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212533.
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Nazer, Ali. "Joint source-channel coding and unequal error protection of CELP 1016 encoded speech over very noisy channels". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0003/MQ28243.pdf.
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Lefèvre, Pascal. "Protection des contenus multimédias pour la certification des données". Thesis, Poitiers, 2018. http://www.theses.fr/2018POIT2273/document.
Testo completoAbstract (sommario):
Depuis plus de vingt ans, l'accès à la technologie est devenu très facile étant donné son omniprésence dans le quotidien de chacun et son faible coût. Cet accès aux technologies du numérique permet à toute personne équipée d'un ordinateur ou d'un smartphone de visualiser et de modifier des contenus digitaux. Avec les progrès en matière de stockage en ligne, la quantité de contenus digitaux tels que le son, l'image ou la vidéo sur internet a explosé et continue d'augmenter.Savoir identifier la source d'une image et certifier si celle-ci a été modifiée ou non sont des informations nécessaires pour authentifier une image et ainsi protéger la propriété intellectuelle et les droits d’auteur par exemple. Une des approches pour résoudre ces problèmes est le tatouage numérique. Il consiste à insérer une marque dans une image qui permettra de l'authentifier.Dans cette thèse, nous étudions premièrement le tatouage numérique dans le but de proposer des méthodes plus robustes aux modifications d'image grâce aux codes correcteurs. En étudiant la structure des erreurs produites par la modification d’une image marquée, un code correcteur sera plus efficace qu’un autre. Nous proposons aussi d’intégrer de nouveaux codes correcteurs appelés codes en métrique rang pour le tatouage.Ensuite, nous proposons d’améliorer l'invisibilité des méthodes de tatouage pour les images couleur. A l’insertion d’une marque, les dégradations de l’image sont perçues différemment par le système visuel humain en fonction de la couleur. Nous proposons un modèle biologique de la perception des couleurs qui nous permet de minimiser les distorsions psychovisuelles de l’image à l’insertion.Toutes ces techniques sont testées sur des images naturelles dans un contexte d’insertion d’informationFor more than twenty years, technology has become more and more easy to access. It is omnipresent in everyday life and is low cost. It allows anyone using a computer or a smartphone to visualize and modify digital contents. Also, with the impressive progress of online massive data storage (cloud), the quantity of digital contents has soared and continues to increase. To ensure the protection of intellectual property and copyright, knowing if an image has been modified or not is an important information in order to authenticate it. One approach to protect digital contents is digital watermarking. It consists in modifying an image to embed an invisible mark which can authenticate the image. In this doctorate thesis, we first study how to improve the robustness of digital image watermarking against image processings thanks to error correcting codes. By studying the error structure produced by the image processing applied on a watermarked image, we can find an optimal choice of error correcting code for the best correction performances. Also, we propose to integrate a new type of error correcting codes called rank metric codes for watermarking applications. Then, we propose to improve the invisibility of color image watermarking methods. At the embedding step, a host image suffers some distortions which are perceived differently in function of the color by the human visual system. We propose a biological model of color perception which allows one to minimize psychovisual distortions applied on the image to protect
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Karaer, Arzu. "Optimum bit-by-bit power allocation for minimum distortion transmission". Texas A&M University, 2005. http://hdl.handle.net/1969.1/4760.
Testo completoAbstract (sommario):
In this thesis, bit-by-bit power allocation in order to minimize mean-squared error (MSE) distortion of a basic communication system is studied. This communication system consists of a quantizer. There may or may not be a channel encoder and a Binary Phase Shift Keying (BPSK) modulator. In the quantizer, natural binary mapping is made. First, the case where there is no channel coding is considered. In the uncoded case, hard decision decoding is done at the receiver. It is seen that errors that occur in the more significant information bits contribute more to the distortion than less significant bits. For the uncoded case, the optimum power profile for each bit is determined analytically and through computer-based optimization methods like differential evolution. For low signal-to-noise ratio (SNR), the less significant bits are allocated negligible power compared to the more significant bits. For high SNRs, it is seen that the optimum bit-by-bit power allocation gives constant MSE gain in dB over the uniform power allocation. Second, the coded case is considered. Linear block codes like (3,2), (4,3) and (5,4) single parity check codes and (7,4) Hamming codes are used and soft-decision decoding is done at the receiver. Approximate expressions for the MSE are considered in order to find a near-optimum power profile for the coded case. The optimization is done through a computer-based optimization method (differential evolution). For a simple code like (7,4) Hamming code simulations show
that up to 3 dB MSE gain can be obtained by changing the power allocation on the
information and parity bits. A systematic method to find the power profile for linear block codes is also introduced given the knowledge of input-output weight enumerating function of the code. The information bits have the same power, and parity bits
have the same power, and the two power levels can be different.
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Wu, Zhenyu, Ali Bilgin e Michael W. Marcellin. "JOINT SOURCE/CHANNEL CODING FOR TRANSMISSION OF MULTIPLE SOURCES". International Foundation for Telemetering, 2005. http://hdl.handle.net/10150/604932.
Testo completoAbstract (sommario):
ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, NevadaA practical joint source/channel coding algorithm is proposed for the transmission of multiple images and videos to reduce the overall reconstructed source distortion at the receiver within a given total bit rate. It is demonstrated that by joint coding of multiple sources with such an objective, both improved distortion performance as well as reduced quality variation can be achieved at the same time. Experimental results based on multiple images and video sequences justify our conclusion.
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Beltrão, Neto Humberto Vasconcelos [Verfasser]. "Analysis and Design of Modern Coding Schemes for Unequal Error Protection and Joint Source-Channel Coding / Humberto Vasconcelos Beltrão Neto". Aachen : Shaker, 2012. http://d-nb.info/1067735119/34.
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Chenette, Nathan Lee. "Symmetric schemes for efficient range and error-tolerant search on encrypted data". Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/48976.
Testo completoAbstract (sommario):
Large-scale data management systems rely more and more on cloud storage, where the need for efficient search capabilities clashes with the need for data confidentiality. Encryption and efficient accessibility are naturally at odds, as for instance strong encryption necessitates that ciphertexts reveal nothing about underlying data. Searchable encryption is an active field in cryptography studying encryption schemes that provide varying levels of efficiency, functionality, and security, and efficient searchable encryption focuses on schemes enabling sub-linear (in the size of the database) search time. I present the first cryptographic study of efficient searchable symmetric encryption schemes supporting two types of search queries, range queries and error-tolerant queries. The natural solution to accommodate efficient range queries on ciphertexts is to use order-preserving encryption (OPE). I propose a security definition for OPE schemes, construct the first OPE scheme with provable security, and further analyze security by characterizing one-wayness of the scheme. Efficient error-tolerant queries are enabled by efficient fuzzy-searchable encryption (EFSE). For EFSE, I introduce relevant primitives, an optimal security definition and a (somewhat space-inefficient, but in a sense efficient as possible) scheme achieving it, and more efficient schemes that achieve a weaker, but practical, security notion. In all cases, I introduce new appropriate security definitions, construct novel schemes, and prove those schemes secure under standard assumptions. The goal of this line of research is to provide constructions and provable security analysis that should help practitioners decide whether OPE or FSE provides a suitable efficiency-security-functionality tradeoff for a given application.
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Shiyanovskii, Yuriy. "Reliability of SRAMs and 3D TSV ICS: Design Protection from Soft Errors and 3D Thermal Modeling". Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1334891947.
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Epple, Bernhard [Verfasser], e Hans Jürgen [Akademischer Betreuer] Ohlbach. "Computer based simulation of optical wireless communications for the development of optimized error protection and correction schemes / Bernhard Epple ; Betreuer: Hans Jürgen Ohlbach". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2019. http://d-nb.info/1184794081/34.
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Epple, Bernhard [Verfasser], e Hans Jürgen [Akademischer Betreuer] Ohlbach. "Computer based simulation of optical wireless communications for the development of optimized error protection and correction schemes / Bernhard Epple ; Betreuer: Hans Jürgen Ohlbach". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2018. http://d-nb.info/1180981758/34.
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Gazzoni, Wanessa Carla. "Estudo do emaranhamento quantico com base na teoria da codificação cloassica". [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261091.
Testo completoAbstract (sommario):
Orientadores: Reginaldo Palazzo Junior, Carlile LavorTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-11T20:14:12Z (GMT). No. of bitstreams: 1 Gazzoni_WanessaCarla_D.pdf: 915784 bytes, checksum: d9b26e53c10c74a95fabe11a016027ce (MD5) Previous issue date: 2008
Resumo: Este trabalho apresenta algumas contribuições para um melhor entendimento do emaranhamento quântico e suas aplicações. Com o propósito de obter a classificação de estados quânticos puros arbitrários em separáveis ou emaranhados, apresentamos um critério de separabilidade do qual tal classificação decorre. Este critério está baseado em uma interpretação homológicageométrica, que nos permitiu formalizar algumas conclusões acerca da quantificação do emaranhamento em estados puros arbitrários com três qubits. A partir desta interpretação, foi possível também associar a descriçãao do conteúdo dos kets de um estado puro arbitrário a conceitos de teoria da codificação clássica. Tendo como base esta associação, propomos uma forma bastante simplificada para determinar a descrição matemática de estados puros arbitrários que satisfazem o máximo emaranhamento global. De acordo com conceitos da teoria da codificação, analisamos os estados de máximo emaranhamento global com relaçãoo 'a proteção contra erros que esses estados possuem. Neste contexto, apresentamos uma nova classe de estados que ainda Não havia sido mencionada na literatura.
Abstract: In this thesis we present some contributions to a better understanding of quantum entanglement and its applications. With the purpose of obtaining a classification of the arbitrary pure quantum states as separable or entangled, a separability criterion is presented. This criterion is based on an homologic-geometric interpretation which allowed us to formalize some conclusions on the entanglement quantification of arbitrary pure states with three qubits. From this interpretation, it was possible to associate a description of the kets' content of an arbitrary pure state with the concepts of the classical coding theory. Based on this association, we propose a simplified form to determine a mathematical description of arbitrary quantum states satisfying the maximum global entanglement. From the concepts of coding theory we considered the states of maximum global entanglement with respect to its inherent error protection. In this context, we present a new class of states satisfying all the previous properties and which were not known in the open literature.
Doutorado
Telecomunicações e Telemática
Doutor em Engenharia Elétrica
32
Abdurrhman, Ahmed B. M. "Error resilient video communications using high level M-QAM : modelling and simulation of a comparative analysis of a dual-priority M-QAM transmission system for H.264/AVC video applications over band-limited and error-phone channels". Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4913.
Testo completoAbstract (sommario):
An experimental investigation of an M level (M = 16, 64 and 256) Quadrature Amplitude Modulation (QAM) transmission system suitable for video transmission is presented. The communication system is based on layered video coding and unequal error protection to make the video bitstream robust to channel errors. An implementation is described in which H.264 video is protected unequally by partitioning the compressed data into two layers of different visual importance. The partition scheme is based on a separation of the group of pictures (GoP) in the intra-coded frame (I-frame) and predictive coded frame (P frame). This partition scheme is then applied to split the H.264-coded video bitstream and is suitable for Constant Bit Rate (CBR) transmission. Unequal error protection is based on uniform and non-uniform M-QAM constellations in conjunction with different scenarios of splitting the transmitted symbol for protection of the more important information of the video data; different constellation arrangements are proposed and evaluated to increase the capacity of the high priority layer. The performance of the transmission system is evaluated under Additive White Gaussian Noise (AWGN) and Rayleigh fading conditions. Simulation results showed that in noisy channels the decoded video can be improved by assigning a larger portion of the video data to the enhancement layer in conjunction with non-uniform constellation arrangements; in better channel conditions the quality of the received video can be improved by assigning more bits in the high priority channel and using uniform constellations. The aforementioned varying conditions can make the video transmission more successful over error-prone channels. Further techniques were developed to combat various channel impairments by considering channel coding methods suitable for layered video coding applications. It is shown that a combination of non-uniform M-QAM and forward error correction (FEC) will yield a better performance. Additionally, antenna diversity techniques are examined and introduced to the transmission system that can offer a significant improvement in the quality of service of mobile video communication systems in environments that can be modelled by a Rayleigh fading channel.
33
Abdurrhman, Ahmed B. M. "Error relilient video communications using high level M-QAM. Modelling and simulation of a comparative analysis of a dual-priority M-QAM transmission system for H.264/AVC video applications over band-limited and error-phone channels". Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4913.
Testo completoAbstract (sommario):
An experimental investigation of an M level (M = 16, 64 and 256) Quadrature Amplitude Modulation (QAM) transmission system suitable for video transmission is presented. The communication system is based on layered video coding and unequal error protection to make the video bitstream robust to channel errors. An implementation is described in which H.264 video is protected unequally by partitioning the compressed data into two layers of different visual importance. The partition scheme is based on a separation of the group of pictures (GoP) in the intra-coded frame (I-frame) and predictive coded frame (P frame). This partition scheme is then applied to split the H.264-coded video bitstream and is suitable for Constant Bit Rate (CBR) transmission. Unequal error protection is based on uniform and non-uniform M-QAM constellations in conjunction with different scenarios of splitting the transmitted symbol for protection of the more important information of the video data; different constellation arrangements are proposed and evaluated to increase the capacity of the high priority layer. The performance of the transmission system is evaluated under Additive White Gaussian Noise (AWGN) and Rayleigh fading conditions.
Simulation results showed that in noisy channels the decoded video can be improved by assigning a larger portion of the video data to the enhancement layer in conjunction with non-uniform constellation arrangements; in better channel conditions the quality of the received video can be improved by assigning more bits in the high priority channel and using uniform constellations. The aforementioned varying conditions can make the video transmission more successful over error-prone channels. Further techniques were developed to combat various channel impairments by considering channel coding methods suitable for layered video coding applications. It is shown that a combination of non-uniform M-QAM and forward error correction (FEC) will yield a better performance. Additionally, antenna diversity techniques are examined and introduced to the transmission system that can offer a significant improvement in the quality of service of mobile video communication systems in environments that can be modelled by a Rayleigh fading channel.
34
Bring, Hampus, e Olle Emanuelsson. "Vinkelfelet i mätkretsens påverkan på riktade jordfelsskydd". Thesis, Högskolan Väst, Avd för automationssystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-7511.
Testo completoAbstract (sommario):
Utfört examensarbete undersöker vinkelfelet i mätkretsen för riktade jordfelsskydd och hur det påverkar dess felbortkoppling. Uppkomna vinkelfel i mätkretsen kan påverka det riktade jordfelsskyddet så att verklig felström och uppmätt felström inte stämmer överens, vilket kan leda till uteblivna eller obefogade felbortkopplingar. Vattenfall ställer krav på att vinkelfelet får uppgå till max ±2 grader för mätkretsen. Eftersom vinkelfelet i många fall har en hög påverkan på jordfelsskyddets noggrannhet undersöks vad Vattenfalls vinkelkrav egentligen innebär. Största orsaken till vinkelfelet uppstår oftast i strömtransformatorn och därför undersöks hur mycket två strömtransformatorer med olika klassificeringar som är vanliga i elnätet påverkar vinkelfelet i mätkretsen. Jordfel är det vanligast uppkomna felet i mellanspänningsnät och dess storlek beror till stor del på hur mycket kapacitivt bidrag som finns på linjerna samt värdet på nollpunktsresistorn. Det kapacitiva bidraget från linjen kompenseras centralt i fördelningsstationen och ibland lokalt ute på ledningen. Den högst tillåtna centralt kompenserade delen av en linje får vara 30 A, vid reservdrift av en linje kan denna del uppgå till 60 A. Vinkelfelet har en högre påverkan vid stora kapacitiva bidrag och vid låga värden på nollpunktsresistorn. I många fall sitter det flera riktade jordfelsskydd på samma linje där selektivitet alltid eftersträvas. Vinkelfelet kan ha en negativ påverkan på denna selektivitet. Genom beräkningar, simuleringar och provningar har ett antal slutsatser dragits. Vattenfalls vinkelkrav ger en otydlig bild angående tillåten påverkan på jordfelsskyddet. Med rätt val av strömtransformator påvisas att det troligtvis är möjligt att skärpa vinkelkravet. För att minska vinkelfelets påverkan kan den högst tillåtna centralt kompenserade delen minskas och/eller öka värdet på nollpunktsresistorn. En beloppsselektivitet på 1000 Ω kan inte alltid tillämpas då vissa fall kräver en beloppsselektivitet på 2000 Ω. Genom att sätta nollpunktsspänningen som utlösningsvillkor och nollpunktsströmmen som frigivningsvillkor kan enligt studien troligen ett noggrannare jordfelsskydd uppnås.This bachelor's thesis examines the angular error in the measurement circuit for directional earth-fault protection and how this error affects the fault disconnection. Angular errors in the measurement circuit can affect the directional earth-fault protection in such a way that the real fault current and the measured fault current do not match. This can lead to missed or unwarranted fault disconnections. Vattenfall has a requirement which states that the angular error must not exceed ±2 degrees for the measurement circuit. Since the angular error in many cases has a high impact on the earth-fault accuracy, an investigation concerning what Vattenfalls angle requirement really means. The main cause of the angular error usually occurs in the current transformers and therefore two commonly used current transformers in the grid with different classifications and their impact on the angular error in the measurement circuit are examined. Ground fault is the most common fault which occurs in a distribution network, its size depends largely on the amount of capacitive current which the grid contributes with as well as the size of the neutral grounding resistor. The capacitive contribution of the grid compensates centrally in the distribution station and sometimes locally on the line. The maximum permitted centrally compensated part of a line is limited to 30 A, this central part can go up to 60 A in case the line needs to be fed from a second distribution station. The angular error has a higher impact if the capacitive contribution is high and for low values of the neutral grounding resistor. In many cases more than one earth-fault protection are found on the same line, in these cases selectivity is always pursued. The angular error may have a negative effect on the selectivity. By calculations, simulations and tests a number of conclusions can be drawn. Vattenfalls angle requirement gives an unclear picture concerning the permitted impact on the earthfault protection. Moreover selecting the correct current transformer demonstrates that the angular requirement can probably be sharpened. To reduce the influence of the angular error the maximum permitted centrally compensated part be reduced and/or the value of the neutral grounding resistor can be increased. A selectivity of 1000 Ω can not always be applied since certain cases require a selectivity of 2000 Ω. By setting the zero sequence voltage as the trigger condition and the zero sequence current as the realese condition, according to this study it may be possible to achieve a more accurate earth-fault protection.
35
Malach, Roman. "Zabezpečení přenosu dat proti dlouhým shlukům chyb". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217264.
Testo completoAbstract (sommario):
This Master´s thesis discuses the protection of data transmission against long error bursts. The data is transmited throught the channel with defined error rate. Parameters of the channel are error-free interval 2000 bits and length of burst error 250 bits. One of the aims of this work is to make a set of possible methods for the realization of a system for data correction. The basic selection is made from most known codes. These codes are divided into several categories and then the best one is chosen for higher selection. Of course interleaving is used too. Only one code from each category can pass on to the higher level of the best code selection. At the end the codes are compared and the best three are simulated using the Matlab program to check correct function. From these three options, one is chosen as optimal regarding practical realization. Two options exist, hardware or software realization. The second one would seem more useful. The real codec is created in validator language C. Nowadays, considering language C and from a computer architecture point of view the 8 bits size of element unit is convenient. That´s why the code RS(255, 191), which works with 8 bits symbols, is optimal. In the next step the codec of this code is created containing the coder and decoder of the code above. The simulation of error channel is ensured by last program. Finally the results are presented using several examples.
36
Wu, Chi-Jen, e 巫啟禎. "New Constructions of Equal Error Protection and Unequal Error Protection QC-LDPC Codes". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/7j7e83.
Testo completoAbstract (sommario):
博士國立清華大學
通訊工程研究所
104
Low-density parity-check (LDPC) block codes have been shown to have near-capacity perfor- mance with iterative message-passing decoding and sufficiently long block length. However, quite a number of methods for designing LDPC block codes are based on random construc- tions; the lack of structures leads to serious disadvantages of high complexity in encoding and decoding. Therefore, in recent researches, codes with algebraic structures have been devel- oped, among which quasi-cyclic LDPC (QC-LDPC) codes are an important class. They can be encoded and decoded with low complexity, suitable for many applications such as packet- switching networks. In this dissertation, we first develop new constructions of QC-LDPC codes with good distance and girth properties. Simulation results show that the constructed codes can have better error performance than previous codes at high signal-to-noise ratios. Constructions of unequal error protection (UEP) QC-LDPC codes are also provided in this dissertation. A criterion for constructing UEP QC-LDPC codes via the masking technique is given, based on which explicit conditions on the base parity-check matrices and masking matrices are provided. Three specific constructions of UEP QC-LDPC codes are also presented. Furthermore, a sufficient condition to ensure strict UEP is developed. Simulation results show that the constructed UEP codes can indeed provide coded bits with different protection levels and perform better than traditional time-sharing schemes. Finally constructions of variable-rate UEP QC-LDPC codes are developed. The criteria which guarantee that a higher-rate QC-LDPC code can be obtained by adding column-blocks to or removing row-blocks from the parity-check matrix of a given lower-rate QC-LDPC code are provided. Then the conditions on the base parity-check matrices and masking matrices are given. We also present specific constructions of variable-rate UEP QC-LDPC codes. Simulation results show that all the constructed codes can indeed provide coded bits with different error-correcting capabilities and have good error performance.
37
"Techniques for unequal error protection". 2001. http://library.cuhk.edu.hk/record=b5890836.
Testo completoAbstract (sommario):
Ho Man-Shing.Thesis (M.Phil.)--Chinese University of Hong Kong, 2001.
Includes bibliographical references (leaves 65-66).
Abstracts in English and Chinese.
Acknowledgement --- p.i
Abstract --- p.ii
List of Abbreviation --- p.iii
Chapter 1. --- Introduction --- p.1
Chapter 1.1 --- Digital Communication System --- p.3
Chapter 1.2 --- Thesis Organization --- p.4
Chapter 2. --- Error-Correcting Codes --- p.6
Chapter 2.1 --- Convolutional Codes --- p.7
Chapter 2.1.1 --- Generator Polynomials --- p.8
Chapter 2.1.2 --- Generator Matrix --- p.9
Chapter 2.1.3 --- Circuit Diagram --- p.10
Chapter 2.1.4 --- State-transition Diagram --- p.11
Chapter 2.1.4 --- Trellis Diagram --- p.12
Chapter 2.1.5 --- Distance property --- p.13
Chapter 2.2 --- Rate-Compatible Punctured Convolutional Codes --- p.14
Chapter 2.3 --- Trellis-Coded Modulation --- p.17
Chapter 2.3.1 --- General Model of TCM --- p.18
Chapter 2.3.2 --- Trellis Representation --- p.20
Chapter 2.3.3 --- Set Partitioning --- p.21
Chapter 2.3.4 --- Code Modulation --- p.23
Chapter 2.4 --- Decoding Algorithm --- p.25
Chapter 2.4.1 --- Viterbi Algorithm --- p.27
Chapter 2.4.2 --- List Viterbi Algorithm --- p.30
Chapter 3. --- Unequal-Error-Protection for Embedded Image Coder --- p.33
Chapter 3.1 --- SPIHT Coder --- p.35
Chapter 3.1.1 --- Progressive Image Transmission --- p.36
Chapter 3.1.2 --- Set Partitioning Sorting Algorithm --- p.37
Chapter 3.1.3 --- Spatial Orientation Trees --- p.38
Chapter 3.2 --- System Description --- p.39
Chapter 3.3 --- Code Allocation --- p.41
Chapter 3.4 --- System Complexity --- p.42
Chapter 3.5 --- Simulation Result --- p.43
Chapter 4. --- Unequal-Error-Protection Provided by Trellis-Coded Modulation --- p.51
Chapter 4.1 --- System Description --- p.52
Chapter 4.2 --- Unequal Constellation --- p.53
Chapter 4.3 --- Free Distance --- p.55
Chapter 4.4 --- Simulation Results --- p.59
Chapter 5. --- Conclusion --- p.63
Bibliography --- p.65
38
Cheng, Tsung-Chao, e 鄭宗超. "Error Protection of SPIHT Coded Images". Thesis, 1999. http://ndltd.ncl.edu.tw/handle/56777210113503105492.
Testo completoAbstract (sommario):
碩士國立臺北科技大學
電腦通訊與控制研究所
87
With the rapid growth of Internet and wireless communications , images and video are widely applied to multimedia services. Efficient compression and reliable transmission of image and video information have there for become one of the most interesting research issues. The embedded zerotree wavelet (EZW) coding, first introduced by Shapiro in 1993, has become one of the most successful and practical algorithms for still image and video compress codecs. Owing to its excellent rate-distortion performance, low implementing complexity, and capability for scalable transmission, the EZW-based method has been adopted as an option in MPEG-4 and will act as a strong candidate for JPEG-2000. Among the various EZW approaches, the set partitioning in hierarchical trees (SPIHT) technique proposed by Said and Pearlman stands the simplest and most efficient. As compared to the conventional DCT-based coding algorithms, the lack of transmission robustness over noisy channels has become the Achilles' heel of all the EZW-based coding algorithms. The transmission errors usually cause only local and limited degradation for DCT-based algorithms such as JPEG, MPEG-l and MPEG-2. However, just a few transmission errors may cause the EZW-based decoder to render a poorly reconstructed image. In this thesis, we first investigate the effects of channel noise on coded images. We then develop an efficient error-resilient scheme for SPIHT-coded images. By partitioning the data sequence with appropriate side information, the proposed algorithm can provide significantly better performance (in average PSNR) over noisy channels than the original SPIHT coding. Furthermore, the increase of the coding complexity needed for the modification is minimal as compared with other robust SPIHT algorithms.
39
Wang, Chung-Hsuan, e 王忠炫. "Convolutional Codes for Unequal Error Protection". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/43762352703109476965.
Testo completoAbstract (sommario):
博士國立清華大學
電機工程學系
89
Channel coding for unequal error protection (UEP), which can provide different protecting efforts with respect to different protection requirements, has recently attracted significant research interests, since it can make the best use of the channel bandwidth for many practical applications. This thesis investigates convolutional codes, one of the most popular coding schemes in digital communication systems, for the application of UEP. From an algebraic theory point of view, we make a full exploration of the UEP capability of convolutional codes, based on which general properties about combining the optimality, canonicity, and minimality of generator matrices are clarified. We also focus on the construction of powerful UEP schemes comprising convolutional codes for practical applications. A new class of path-compatible pruned convolutional (PCPC) codes with the flexible and powerful capabilities of UEP are invented. Besides, a concatenated super-imposed rate-compatible punctured convolutional (SI-RCPC) coder is constructed for UEP channel coding in wireless speech communications. For the study of UEP convolutional codes, necessary and sufficient conditions together with a procedure for obtaining an optimal and basic generator matrix with the smallest external degree are given. We also demonstrate the existence of a canonical generator matrix which has the greatest separation vector among all canonical generator matrices for every convolutional code. Necessary and sufficient conditions as well as a procedure are presented for obtaining such a canonical generator matrix of the best UEP capability. By a counterexample, we show that the set of optimal generator matrices for a given convolutional code may contain no systematic generator matrices. A constructive proof is then provided to show the existence of a systematic generator matrix with the greatest separation vector, based on which a procedure is invented for obtaining such a best systematic generator matrix. For the construction of powerful UEP schemes, path pruning is proposed to achieve free distance enlargement for convolutional codes. Through path pruning, every convolutional code can be used for UEP, no matter whether it is originally a UEP code. To avoid the undesired path discontinuity and reduce the possible path distance loss, a cascaded implementation together with a path-compatible criterion is proposed for path pruning, under which PCPC codes are constructed. Necessary and sufficient conditions are derived for a sub-class of PCPC codes whose decoding can be done by a single decoder for the parent code, and some of this kind of PCPC codes with good UEP capabilities found by computer search are given as well. For wireless speech communications, a general methodology is presented for the combined design of the speech and channel coding, based on which a combined variable-rate code-excited linearly predictive (QCELP) speech coding and UEP channel coding system is constructed. In contrast to the conventional schemes, our system employs a concatenated SI-RCPC channel coder which can provide UEP with respect to not only the bit-significance of speech packets but also the speech activity and local channel characteristics. Verified by the simulation results, the combined system achieves an average transmission rate less than 8 kbps as well as an average 2 dB signal-to-noise ratio gain over the conventional equal error protection system.
40
Lee, Way-Long, e 李威龍. "Coded modulation for unequal error protection". Thesis, 1993. http://ndltd.ncl.edu.tw/handle/68370498924066644992.
Testo completo
41
Chiou, Shian-Jiun, e 邱顯鈞. "Space-Time codes for Uneqaul Error Protection". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/79251116988964907463.
Testo completoAbstract (sommario):
碩士中原大學
電子工程研究所
92
With the progress of science and society, the demands for wireless multimedia services increase rapidly. However, the signals transmitted over wireless channels usually experience serious distortion due to the corruption of multipath fading and thermal noise. Space-time codes, which combine both of the spatial and temporal diversities, have been shown to provide excellent performance against the fading effect. Coding techniques for unequal error protection (UEP), which can provide different protecting efforts with respect to different protection requirements, can make the best use of channel bandwidth in many practical applications. In this thesis, space-time codes are combined with UEP for channel coding of high-rate wireless multimedia communications. We study the UEP capabilities of space-time codes from an algebraic viewpoint. The performance analysis together with some design criteria of the UEP space-time codes are presented. We also propose several schemes for constructing the space-time codes of powerful UEP capabilities, based on which tables of good UEP codes with various rates and memories are given.
42
Shen, Pao Ming, e 沈保明. "Channel Error Protection for Vector-Quantized Images". Thesis, 1995. http://ndltd.ncl.edu.tw/handle/64003130390663982583.
Testo completo
43
Meng-Hui, Lin. "Investigation of Lossy Error Protection for Error-Resilient H.264/AVC Video Transmission". 2005. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2407200515371800.
Testo completo
44
Lin, Meng-Hui, e 林孟輝. "Investigation of Lossy Error Protection for Error-Resilient H.264/AVC Video Transmission". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/87385385863883182300.
Testo completoAbstract (sommario):
碩士國立臺灣大學
資訊工程學研究所
93
Recent research efforts on distributed video coding and Wyner-Ziv problems have revealed an exciting, new possibility for video applications. The Wyner-Ziv coding paradigm has suggested a novel protection scheme that can effectively combat packet losses. In this thesis, we investigate the application of lossy error protection for H.264/AVC video streaming over wireless network. Video waveforms are protected using the Wyner-Ziv coding concept, resulting in graceful video quality degradation in the presence of increasing network error rate. In addition, we propose a feedback-based network adaptation algorithm to dynamically optimize the performance of error protection in the presence of changing network dynamics. In our design, we have applied the systematic error protection framework to the baseline H.264/AVC video stream. The systematic portion consists of unprotected video bitstream. At the same time, the Wyner-Ziv encoder generates the second, coarser representation of the unprotected, original video bitstream at much lower rate than the original. Then, the Wyner-Ziv decoder utilized the side information from the video decoder to reconstruct the coarse video waveform. When network packets are lost, the erroneous video frame can be recovered by the coarse video waveform. As a result, the video distortion caused by network packet loss is bounded by the Wyner-Ziv description. The Wyner-Ziv decoder also sends feedback messages to the Wyner-Ziv encoder; then the Wyner-Ziv encoder can adapt to varying network condition and achieve graceful video quality degradation. Based on our experimental results, we have shown that lossy error protection can provide acceptable, eye-pleasing video quality over a large range of packet loss rates. When combining with our network adaptation algorithm, we have shown that the lossy error protection scheme can be further enhanced to provide smooth quality adaptation for H.264/AVC video transmission over wireless network.
45
Ding, Jun-Ren, e 丁俊仁. "A Study of Unequal Error Protection for Transmission". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/04604739563327783359.
Testo completo
46
Hsu, Chih-Hsiang, e 徐志祥. "Orthogonally Multiplexed Modulation Signals with Unequal Error Protection". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/92398445665669579025.
Testo completoAbstract (sommario):
碩士國立中央大學
電機工程研究所
91
Orthogonally Multiplexed Modulation signals are investigated in this thesis .The research focus is on the application of the unequal error protection to the Orthogonally-Multiplexed Modulation signals. First , the energy allocation among the component signals of Orthogonally Multiplexed Modulation is optimized by minimizing a modified symbol error function in AWGN channel and the scheme performance is observed. Second, the different R-S coding rate for the component signals of Orthogonally Multiplexed Modulation is used. The performance comparison between using the same R-S coding rate and using the different R-S coding rate Orthogonally Multiplexed Modulation system is presented.
47
Li, Chien-Hao, e 李健豪. "Unequal Error Protection on SLCCA Image Encoded Bit Stream". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/10413855891662040993.
Testo completoAbstract (sommario):
碩士國立中山大學
資訊工程學系研究所
90
In SLCCA , the location and magnitude of significant coefficients are specified by the so-called significance map and magnitude respectively . As we know significance map is susceptible , error will propagate when data was deteriorated . This paper address this critical problem and provide an novel approach . In the significance map , the importance of data is interlaced . And our approach is to re-organize the significant map according to encoded symbol’s characteristic . In SLCCA , four symbols are used to encode : POS , NEG , ZERO , LINK . POS or NEG represents the sign of a significant coefficient . ZERO represents an insignificant coefficient . LINK marks the presence of a significance-link . Symbol LINK is more important than POS NEG ZERO . Because when error happen in symbol LINK , it will lead to propagation error . Re-organized data is protected by differRS code . More important data are allocated more parity symbols .
48
林怡馨. "Pruned and punctured convolutional codes for unequal error protection". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/13324002847820934879.
Testo completo
49
Huang, Jia-Jyun, e 黃嘉俊. "Study of Unequal Error Protection for Wireless Transmission Application". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/55182694720123318369.
Testo completoAbstract (sommario):
碩士國立雲林科技大學
電機工程系碩士班
94
Because the fruitful and diversified contents of multimedia communication and the vulnerable environment of wireless transmission, applying unequal error protection is now an active research topic .In the paper, we propose a novel error rate weighted transmission scheme which combines Trellis Coded Modulation (TCM) and Non-uniform QAM. Based on weighting the grade of error protection requirement of data itself by differentiating their transmission quality demands, we utilize the characteristics of Gray (reflection) code and combine with the non-uniform QAM and TCM to attain the unequal protection purpose in which we have chosen the convolution code in TCM and QAM 。From this design, we are able to control the transmission protection by grade of weighting and can adaptively change the weighting according the bit-to-bit service demand in the data streams. Such design can fulfilled with the physical layers of current standards such as DVB or WiMax.To verify the performance and comparison, we perform the simulation based on 16-QAM and 64-QAM under the ISI channel and pure AWGN channel, respectively. The results show that the error protection performance by differentiating their grade of weighting is greatly improves as expected.
50
Huang, Han-Ting, e 黃瀚霆. "Image Transmission Using Polar Codes and Unequal Error Protection". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/ah68t6.
Testo completoAbstract (sommario):
碩士國立臺灣科技大學
電子工程系
106
With the advancement and convenience of technology, image transmission is required for many applications. Since the pixels of the images have different weight of bits, we usually use unequal error protection (UEP) to transmit the images. There are many ways to combine UEP for use in image transmission in the existing literature, such as combining with turbo codes or LDPC codes. In recent years, there has been a new error correction scheme called polar codes. Polar codes use code construction to find out which channels are good for transmitting the information. Due to their good property, polar codes have become one of the 5G communication standards. Because polar codes are the latest emerging error correction code, and also because there are not much research on polar codes with image transmission, we want to study the combination of polar codes and UEP for image transmission. It is a key issue to do code construction for polar codes, because we need to find out good channels for sending the information bits. In our method, we use Gaussian approximation (GA) to construct the channel and propose four kinds of situations to simulate: image using GA-sorted order, image with UEP using GA-sorted order, image using natural order and image with UEP using natural order. At the end, in order to improve the visual effect of the recover image within a SNR range, we will use median filter to filter out the salt-and-pepper (SAP) noise in the image. Compared with others, our method propose the recovers images to get higher PSNR and better visual effect at low-to-medium SNR range.