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Video quality prediction for video over wireless access networks (UMTS and WLAN)Khan, Asiya January 2011 (has links)
Transmission of video content over wireless access networks (in particular, Wireless Local Area Networks (WLAN) and Third Generation Universal Mobile Telecommunication System (3G UMTS)) is growing exponentially and gaining popularity, and is predicted to expose new revenue streams for mobile network operators. However, the success of these video applications over wireless access networks very much depend on meeting the user’s Quality of Service (QoS) requirements. Thus, it is highly desirable to be able to predict and, if appropriate, to control video quality to meet user’s QoS requirements. Video quality is affected by distortions caused by the encoder and the wireless access network. The impact of these distortions is content dependent, but this feature has not been widely used in existing video quality prediction models. The main aim of the project is the development of novel and efficient models for video quality prediction in a non-intrusive way for low bitrate and resolution videos and to demonstrate their application in QoS-driven adaptation schemes for mobile video streaming applications. This led to five main contributions of the thesis as follows:(1) A thorough understanding of the relationships between video quality, wireless access network (UMTS and WLAN) parameters (e.g. packet/block loss, mean burst length and link bandwidth), encoder parameters (e.g. sender bitrate, frame rate) and content type is provided. An understanding of the relationships and interactions between them and their impact on video quality is important as it provides a basis for the development of non-intrusive video quality prediction models.(2) A new content classification method was proposed based on statistical tools as content type was found to be the most important parameter. (3) Efficient regression-based and artificial neural network-based learning models were developed for video quality prediction over WLAN and UMTS access networks. The models are light weight (can be implemented in real time monitoring), provide a measure for user perceived quality, without time consuming subjective tests. The models have potential applications in several other areas, including QoS control and optimization in network planning and content provisioning for network/service providers.(4) The applications of the proposed regression-based models were investigated in (i) optimization of content provisioning and network resource utilization and (ii) A new fuzzy sender bitrate adaptation scheme was presented at the sender side over WLAN and UMTS access networks. (5) Finally, Internet-based subjective tests that captured distortions caused by the encoder and the wireless access network for different types of contents were designed. The database of subjective results has been made available to research community as there is a lack of subjective video quality assessment databases.
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Programmes d’évaluation externe de la qualité : étude rétrospective de l’évolution de la qualité des résultats d’analyses de biologie clinique dans trois pays européens / External quality assessment programmes : retrospective analysis on the evolution of results’quality in clinical biology in three European countriesMorandi, Pierre-Alain 02 December 2010 (has links)
L’évaluation externe de la qualité (EEQ) est un outil indispensable qui permet au laboratoire d’analyse de biologie clinique de surveiller la qualité de ses analyses. Une analyse rétrospective sur 391 893 résultats appartenant à sept analytes fréquemment dosés (glucose, calcium, triglycérides, créatine kinase, hémoglobine, HbA1c et protéines urinaires) a été réalisée sur une période de douze ans, de 1996 à 2007. Pour trois analytes, les résultats accumulés par trois Centres européens suisse, français et belge organisant des EEQ ont été comparés. Une approche statistique simple non paramétrique a été utilisée afin de calculer les performances (CV % et pourcentages de résultats conformes interlaboratoires) en incluant tous les résultats des EEQ, y compris les valeurs aberrantes. Le travail a permis de calculer les performances des appareils en fonction des analytes, de comparer les performances entre les Centres et entre deux types d’utilisateurs – les laboratoires professionnels et les cabinets médicaux – et, enfin, de calculer l’évolution des performances dans le temps. Il en ressort que les performances entre les Centres sont comparables et les appareils des laboratoires professionnels obtiennent de meilleures performances par rapport aux petits analyseurs utilisés dans les cabinets médicaux.Concernant les POCT, les performances ne dépendent pas du type d’utilisateur mais du type de POCT : certains obtiennent des performances comparables aux appareils de laboratoire, d’autres inférieures. Globalement, une amélioration des performances est mesurée pour les deux types d’utilisateurs, pour la plupart des appareils et pour tous les analytes. / The external quality assessment (EQA) is an essential tool that allows medical laboratories to supervise the quality of their analyses. A retrospective analysis on 391.893 results originating from seven frequently measured analytes (glucose, calcium, triglycerides, creatine kinase, haemoglobin, HbA1c, and urinary proteins) was performed over a twelveyear period, from 1996 to 2007. For three analytes, the results accumulated by three European Centres – Swiss, French, and Belgian – organising EQA surveys were compared. A simple non-parametrical statistical approach was used to calculate the performances (inter-laboratory CV% and percentage of correct results) in order to include all EQA results, even aberrant values. The work allowed to calculate the performances of devices for the different analytes, to compare performances among the Centres and among two types of users – professional laboratories and medical offices – and, finally to calculate the evolution of performances over time. It turns out that performances among the Centres are comparable and that professional laboratory devices obtained better performances as compared with small laboratory devices used in medical offices. Concerning POCT devices, performances are not linked to the type of user but to the POCT type : certain types reach the same performances as laboratory devices, while others are below. A general improvement of performances is measured for both types of users, for most devices, and for all the analytes.
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Zabezpečování kvality vzdělávání v prostředí vysokých škol / Quality assurance of education in higher educationČrepaňa, Radek January 2009 (has links)
University in providing quality education needs to determine degree of fulfilment of customer needs. Therefore, the college needs to collect feedback on teaching evaluation by students in a systematic evaluation of teaching quality and its assurance. This thesis first looks at examining the current state of the problem in theory. The goal of the theoretical background of the problem is to provide a facilitator for further studying the problem in a particular situation. The output of the study is therefore an overview of the current state of problems in the Czech Republic and development opportunities. The next step is to map and description of current efforts in the system of the University of Economics, Prague. The work also carried out and evaluates own research among students of the faculty on student quality assessment of education. Work on the basis of these findings and analysis summarizes the recommendations in the issues under consideration, including proposals to modify the information system of the school. Another basis for these recommendations is the experiences of other universities. The main contribution is the proposal of the strategic map, which contains the structural elements of the problems embedded in the institution's strategic goals. The final recommendations of this work are a comprehensive summary of the steps necessary for the effective quality assurance of education in a school.
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Vliv regionálních variant španělštiny na kvalitu simultánního tlumočení do češtiny / The Impact of Spanish Regional Varieties on the Quality of Simultaneous Interpreting into CzechBalounová, Zuzana January 2019 (has links)
This theoretical-empirical study deals with the impact of regional varieties of Spanish on the quality of simultaneous interpreting into Czech. The aim of this thesis is to find whether interpreters make more omissions, additions, semantic errors and errors of performance when they interpret from Latin American varieties of Spanish than when they interpret from standard European Spanish as defined by the Royal Spanish Academy (RAE). Another aim is to confirm that different user groups have different expectations regarding the quality of simultaneous interpreting. The theoretical part of this thesis presents findings and conclusions of previous studies. It also provides an overview of strategies and coping mechanisms and a description of some of the Latin American varieties of Spanish. The research part of this study consists of an experiment and a questionnaire survey regarding quality assessment. The empirical part of this thesis presents the results of the experiment and the questionnaire survey.
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Proposta da métrica eVSQM para avaliação de QoE no serviço de streaming de vídeo sobre TCP. / The proposed eVSQM metric for assessing QoE in video streaming over TCP.Zegarra Rodríguez, Demóstenes 12 December 2013 (has links)
Atualmente existem inúmeros serviços multimídia que são transportados através da rede IP, dos quais, o tráfego dos serviços de vídeo experimentou um maior crescimento nos últimos anos. O sucesso de aplicações de streaming de vídeo é um dos fatores pelo qual, este tráfego se incrementou. Alguns recentes estudos projetam que este tipo de serviços no ano 2016, alcançará aproximadamente o 55% do tráfego total da Internet. Considerando a importância que os serviços de vídeo alcançarão nos próximos anos, este trabalho foca-se na avaliação da qualidade de experiência (QoE) dos usuários ao utilizar estes serviços. Assim, nesta tese é proposta uma métrica de avaliação de vídeo denominada eVsQM, do inglês enhanced Video streaming Quality Metric, a qual é baseada principalmente no número, duração e localização temporal dos congelamentos de imagens (pausas) durante uma transmissão de vídeo, considerando também o tipo de conteúdo do vídeo transmitido. Esta métrica foi determinada a partir de um modelo matemático que utilizou os resultados de testes subjetivos de avaliação de vídeo, pois, este tipo de testes são os que melhor se aproximam da QoE real do usuário. Cabe destacar, que na realização dos testes subjetivos foi utilizada uma metodologia concordante com o tipo de degradação que o vídeo possui, ou seja, a pausa. No streaming de vídeo novas soluções são criadas com a finalidade de melhorar a QoE do usuário. O DASH, do inglês Dynamic Adaptive Streaming over HTTP, muda a resolução do vídeo transmitido de acordo com as características da rede. Porém, se a rede é muito flutuante existirão muitas variações de resolução e a QoE do usuário será degradada. Neste trabalho é proposto um parâmetro a ser utilizado no algoritmo DASH que funciona como um limiar para controlar a frequência destas comutações de resolução. Este parâmetro é denominado como SDF (do inglês Switching Degradation Factor) e permite que a QoE mantida em níveis aceitáveis, inclusive em situações onde a rede é muito flutuante. Adicionalmente, neste trabalho é proposto um novo modelo de faturamento nos serviços de telecomunicações, que inclua no processo de tarifação um parâmetro relacionado com a QoE, visando ter uma tarifação de serviços de comunicações mais justa do ponto de vista dos usuários. Desta forma, usuários que recebem uma menor qualidade no serviço devem pagar menos em relação aos usuários que recebem uma melhor qualidade do mesmo serviço. / Nowadays, there are several multimedia services, which are carried via IP networks. From these all services; the traffic regarding video applications had the greatest growth in the last years. The success of video streaming applications is one of the major contributors to video traffic growth. Some recent studies project that video services, will reach approximately 55% of the total Internet traffic in 2016. Considering the relevance that video services will achieve in the coming years, this work focuses on the users Quality of Experience (QoE) when using these services. Thus, this thesis proposes an evaluation metric named enhanced Video streaming Quality Metric (eVsQM), which is based primarily on the number, duration and temporal location of the image freezes (pauses) during a video transmission. Also, this metric considers the video content type and was determined from a mathematical model that used as inputs, the video quality assessment results from subjective tests due, these types of test are the most correlated with real users QoE. It is worth noting that to perform these subjective tests was used a methodology consistent with the kind of video degradation (pause). For another hand, new video streaming solutions are created for the purpose of improving the users QoE of the user. Dynamic Adaptive Streaming over HTTP (DASH) changes the video resolution according to the network characteristics. However, if the network is very fluctuant, many video resolution switching events will be performed and users QoE will be degraded. This thesis proposes a parameter to be used in DASH algorithms that works as a threshold to control the resolution switching frequency. This parameter is named Switching Degradation Factor (SDF) and is responsible to maintain the QoE in acceptable levels, inclusive in scenarios in which the network capacity is very fluctuating.
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Évaluation de la qualité et transmission en temps-réel de vidéos médicales compressées : application à la télé-chirurgie robotisée / Compressed video quality assessment and transmission : application to tele-surgeryNouri, Nedia 09 September 2011 (has links)
L'évolution des techniques chirurgicales, par l'utilisation de robots, permet des interventions mini-invasives avec une très grande précision et ouvre des perspectives d'interventions chirurgicales à distance, comme l'a démontré la célèbre expérimentation « Opération Lindbergh » en 2001. La contrepartie de cette évolution réside dans des volumes de données considérables qui nécessitent des ressources importantes pour leur transmission. La compression avec pertes de ces données devient donc inévitable. Celle-ci constitue un défi majeur dans le contexte médical, celui de l'impact des pertes sur la qualité des données et leur exploitation. Mes travaux de thèse concernent l'étude de techniques permettant l'évaluation de la qualité des vidéos dans un contexte de robotique chirurgicale. Deux approches méthodologiques sont possibles : l'une à caractère subjectif et l'autre à caractère objectif. Nous montrons qu'il existe un seuil de tolérance à la compression avec pertes de type MPEG2 et H.264 pour les vidéos chirurgicales. Les résultats obtenus suite aux essais subjectifs de la qualité ont permis également de mettre en exergue une corrélation entre les mesures subjectives effectuées et une mesure objective utilisant l'information structurelle de l'image. Ceci permet de prédire la qualité telle qu'elle est perçue par les observateurs humains. Enfin, la détermination d'un seuil de tolérance à la compression avec pertes a permis la mise en place d'une plateforme de transmission en temps réel sur un réseau IP de vidéos chirurgicales compressées avec le standard H.264 entre le CHU de Nancy et l'école de chirurgie / The digital revolution in medical environment speeds up development of remote Robotic-Assisted Surgery and consequently the transmission of medical numerical data such as pictures or videos becomes possible. However, medical video transmission requires significant bandwidth and high compression ratios, only accessible with lossy compression. Therefore research effort has been focussed on video compression algorithms such as MPEG2 and H.264. In this work, we are interested in the question of compression thresholds and associated bitrates are coherent with the acceptance level of the quality in the field of medical video. To evaluate compressed medical video quality, we performed a subjective assessment test with a panel of human observers using a DSCQS (Double-Stimuli Continuous Quality Scale) protocol derived from the ITU-R BT-500-11 recommendations. Promising results estimate that 3 Mbits/s could be sufficient (compression ratio aroundthreshold compression level around 90:1 compared to the original 270 Mbits/s) as far as perceived quality is concerned. Otherwise, determining a tolerance to lossy compression has allowed implementation of a platform for real-time transmission over an IP network for surgical videos compressed with the H.264 standard from the University Hospital of Nancy and the school of surgery
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Dubliners\' sob a lupa da lingüística de corpus: uma contribuição para a análise e a avaliação da tradução literária / Dubliners\' s under the Corpus Linguistics: a contribution to the evaluation of literary translationGonçalves, Lourdes Bernardes 08 November 2006 (has links)
Esta tese procura demonstrar a valiosa contribuição da Lingüística de Corpus na análise do texto literário e na avaliação da tradução literária. O corpus é formado pelos textos de Dubliners (1914), uma coletânea de contos de James Joyce, e duas traduções dessa obra, ambas intituladas Dublinenses, uma de Hamilton Trevisan (1964), a outra de José Roberto O Shea (1993). Primeiramente é apresentado um panorama da Lingüística de Corpus, especialmente como uma abordagem que apresenta interfaces com os Estudos da Tradução e a Análise Literária. Em seguida é feita uma análise da obra original e, logo após, uma avaliação das traduções. Para constatar a efetiva contribuição da Lingüística de Corpus, a análise do texto original e das traduções foi realizada seguindo duas abordagens diferentes, a não computacional e a computacional. Os dados levantados foram comparados, o que permitiu estabelecer que a Lingüística de Corpus de fato representa uma abordagem que traz significativa contribuição aos processos de análise do texto literário e à avaliação de traduções literárias. Assim, foi proposto um modelo híbrido de avaliação de tradução literária, que combina características da abordagem tradicional e da Lingüística de Corpus. Esse modelo foi testado com quatro contos de Dubliners. / This thesis aims at demonstrating the valuable contribution of Corpus Linguistics in the analysis of literary texts and in the evaluation of literary translation. The selected texts are Dubliners (1914), a collection of short stories by James Joyce, and two translations thereof, both entitled Dublinenses, one by Hamilton Trevisan (1964), and the other by José Roberto O Shea (1993). Firstly, an analysis of the original work is carried out and, after that, the evaluation of translations. In order to verify the effective contribution of Corpus Linguistics, an analysis of the original text and its translations was performed, using two different approaches, a non computational as well as a computational one. The data thus obtained were compared and, as a result, it could be established that Corpus Linguistics really represents an approach which makes a significant contribution to the processes of literary text analysis and the evaluation of literary translations. Therefore, a model for the evaluation of literary translations was proposed, bringing together characteristics of the traditional approach and that of Corpus Linguistics. This model was then tested on four short stories from Dubliners.
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External quality assessment of health facilities in South Africa : strengths appraised and gaps identifiedMabaso, Kopano Josephine January 2018 (has links)
<b>Background:</b> External Quality Assessment assesses the quality of the structures, processes and outcomes of health facilities using pre-determined standards. South Africa is introducing a national policy on External Quality Assessment, operationalised by a newly established External Quality Assessment agency: the Office of Health Standards Compliance. This thesis seeks to answer three research questions: What is the relationship between External Quality Assessment and patient outcomes (specifically Healthcare Associated Infections) at the specialist-care facility level in South Africa? What are the facilitators of and barriers to health facility performance (i.e. attainment of compliance with standards) in External Quality Assessment at the district hospital level in South Africa? What has been the experience of External Quality Assessment by frontline healthcare workers at the district hospital level in South Africa? <b>Methods:</b> Three systematic literature reviews are conducted that attempt to identify the existing evidence base for the above-mentioned research questions in the international literature. A convergent parallel mixed methods design is used to answer the research questions, comprising an Interrupted Time Series Analysis and a multiple embedded case study of two pairs of health facilities that had undergone External Quality Assessment by the Office of Health Standards Compliance. The Interrupted Time Series Analysis assesses whether an effectiveness relationship can be demonstrated between External Quality Assessment and the Healthcare Associated Infection Methicillin-resistant Staphylococcus Aureus (MRSA) in eight South African specialist-care hospitals using monthly MRSA data from 2004 to 2014. MRSA is used in this thesis as the proxy patient outcome indicator. In order to answer research questions two and three, I participated in a district hospital External Quality Assessment as a participant observer as well as conducted fifteen in-depth interviews with healthcare workers from two pairs of district hospitals and thirteen in-depth interviews with Office of Health Standards Compliance inspectors. These findings are triangulated with health facility External Quality Assessment reports. <b>Results:</b> No conclusive evidence is found of a relationship between implementation of External Quality Assessment and changes in MRSA. The major theoretical lenses drawn from in the analysis of the qualitative findings are systems thinking theory and regulatory theory. The qualitative research suggests that facilitators of performance in External Quality Assessment in South Africa include strong directional leadership within health facilities, a collaborative organisational culture, a whole systems approach, staff development, incentives, a robust information system and a supportive External Quality Assessment agency. The research also identifies poor alignment of External Quality Assessment standards, under-developed and limited human resources, inadequate decision-making space afforded to district hospital leadership, limited financial resources, the use of penalties and negative staff perceptions of External Quality Assessment as barriers to health facility performance in External Quality Assessment. In unpacking the experiences of South African healthcare workers of External Quality Assessment, this research finds that the work of the Office of Health Standards Compliance is valued by healthcare workers as a potential educational opportunity and is useful in providing the health system with a means to compare health facilities using a standardised tool. The implementation of the Office of Health Standards Compliance's External Quality Assessments requires significant improvement and, in their current form, they have potential unintended negative consequences on healthcare worker motivation as well as potentially, inadvertently encouraging the gaming of External Quality Assessment. <b>Conclusion:</b> The Office of Health Standards Compliance is being set up in such a way that once fully established it will be the primary regulator of quality of care in the South African health system. This thesis attempts to identify some of the strengths and weaknesses of this largely under-researched health system intervention and to contribute to strengthening its implementation.
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Estrutura de avaliação da qualidade percebida e desempenho em serviços administrativos de instituição de ensino superiorSteppacher, Damian January 2018 (has links)
O objetivo geral deste trabalho foi construir e aplicar uma estrutura de avaliação da qualidade percebida dos serviços administrativos prestados por servidores técnicos-administrativos em uma Instituição Federal de Ensino Superior (IFES). Para isto, o trabalho se dispôs a: i) levantar um conjunto de atributos e dimensões de qualidade percebida para os serviços administrativos prestados pelos técnicos-administrativos em uma IFES; ii) construir um instrumento de avaliação da qualidade percebida dos serviços administrativos prestados por técnicos-administrativos de uma IFES; iii) analisar gaps de qualidade percebida em serviços administrativos de uma IFES, usando a abordagem IPA (Importance-Performance Analysis), sob a perspectiva de docentes, técnicos-administrativos e discentes; e iv) identificar atributos críticos de qualidade e sua relação com os instrumentos de avaliação de desempenho e de planejamento estratégico na IFES em estudo. Entre as contribuições teóricas deste trabalho estão: i) uma estrutura de atributos para avaliação da qualidade dos serviços administrativos segundo importância e desempenho; e ii) um procedimento metodológico que abrange a hierarquização atributos, a analise dos gaps entre importância e percepção de desempenho, a elaboração e a interpretação da matriz de importância-desempenho. Já as principais contribuições práticas foram: i) a proposta de aperfeiçoamento de instrumentos de avaliação e controle existentes no âmbito da universidade; e ii) a aproximação ao usuário final do serviço, conhecendo sua percepção de qualidade e aspectos valorizados. Assim, ao adotar os procedimentos propostos neste estudo, entende-se que a Universidade estaria promovendo melhorias significativas nos serviços administrativos e avançando na busca pela excelência e qualidade. / This study aims to build and apply a structure of evaluation of the perceived quality of administrative services provided by the administrative staff in Higher Education Federal Institutions (HEFI). For this, the work is organized to i) create a set of attributes and dimensions of perceived quality of administrative services provided by administrative staff in a HEFI; ii) build perceived quality assessment instrument of the administrative services provided by HEFI's administrative staff; iii) analyze perceived quality gaps in administrative services of an HEFIs, using the IPA (Importance-Performance Analysis) approach, from the perspective of teachers, administrative staff, and student; and iv) identify critical attributes of quality and their relationship with instruments of performance and strategic planning in the IFES under study. Among the theoretical contributions of this work are i) an attribute structure to evaluate the quality of administrative services according to importance and performance; and ii) a methodological procedure that includes hierarchical attributes, gap analysis between importance and perception of performance, elaboration and interpretation of the importance-performance matrix. The main practical contributions were i) the proposal to improve existing evaluation and control instruments within the university; and ii) the approach to the end user of the service, knowing its perception of quality and evaluated aspects. Thus, when adopting the procedures proposed in this study, it is understood that the University would be promoting significant improvements in administrative services and advancing in the quest for excellence and quality.
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Objective Perceptual Quality Assessment of JPEG2000 Image Coding Format Over Wireless ChannelChintala, Bala Venkata Sai Sundeep January 2019 (has links)
A dominant source of Internet traffic, today, is constituted of compressed images. In modern multimedia communications, image compression plays an important role. Some of the image compression standards set by the Joint Photographic Expert Group (JPEG) include JPEG and JPEG2000. The expert group came up with the JPEG image compression standard so that still pictures could be compressed to be sent over an e-mail, be displayed on a webpage, and make high-resolution digital photography possible. This standard was originally based on a mathematical method, used to convert a sequence of data to the frequency domain, called the Discrete Cosine Transform (DCT). In the year 2000, however, a new standard was proposed by the expert group which came to be known as JPEG2000. The difference between the two is that the latter is capable of providing better compression efficiency. There is also a downside to this new format introduced. The computation required for achieving the same sort of compression efficiency as one would get with the original JPEG format is higher. JPEG is a lossy compression standard which can throw away some less important information without causing any noticeable perception differences. Whereas, in lossless compression, the primary purpose is to reduce the number of bits required to represent the original image samples without any loss of information. The areas of application of the JPEG image compression standard include the Internet, digital cameras, printing, and scanning peripherals. In this thesis work, a simulator kind of functionality setup is needed for conducting the objective quality assessment. An image is given as an input to our wireless communication system and its data size is varied (e.g. 5%, 10%, 15%, etc) and a Signal-to-Noise Ratio (SNR) value is given as input, for JPEG2000 compression. Then, this compressed image is passed through a JPEG encoder and then transmitted over a Rayleigh fading channel. The corresponding image obtained after having applied these constraints on the original image is then decoded at the receiver and inverse discrete wavelet transform (IDWT) is applied to inverse the JPEG 2000 compression. Quantization is done for the coefficients which are scalar-quantized to reduce the number of bits to represent them, without the loss of quality of the image. Then the final image is displayed on the screen. The original input image is co-passed with the images of varying data size for an SNR value at the receiver after decoding. In particular, objective perceptual quality assessment through Structural Similarity (SSIM) index using MATLAB is provided.
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