Dissertations / Theses on the topic 'Digital Video Broadcasting'

In questo elaborato, dopo una descrizione delle procedure per la creazione degli standard per il il broadcasting numerico adottate dal DVB forum, vengono presi in considerazione i trends del mercato del broadcasting numerico e analizzato in dettaglio lo standard utilizzato per la diffusione televisiva terrestre DVB-T e la sua evoluzione DVB-T2.

This thesis deals with three among the major tasks of a receiver designed for Orthogonal Frequency Division Multiplex (OFDM): i) timing and frequency synchronization, ii) channel estimation and iii) data detection. These problems are very general, since OFDM is used in many different telecommunication environments, however the techniques involved are strongly dependent on the particular scenario. Here we focus on digital video broadcasting standards for terrestrial television. Terrestrial Digital Video Broadcasting, also known as DVB-T, is a broadcasting standard from the European consortium DVB. It is the most widely deployed Digital Terrestrial Television (DTT) system worldwide. The system is based on a transmission of an audio/video stream from the MPEG-2 family, using an OFDM modulation. Besides, in March 2006, the desire to improve the service quality as well as to increase the number of services and the power of the digital television system, has stimulated the DVB group to study some new options for an improved DVB-T standard. A call for technology has been published in 2007, followed in 2009 by the release of the standard for the new generation DVB-T, called DVB-T2. Deployment tests have been studied, and field tests show that DVB-T2, still based on OFDM, can guarantee a 30% increase of the system capacity with respect to its predecessor. As already stated, in both DVB-T standards the elected modulation scheme is OFDM. In fact, OFDM is widely used thanks to its low complexity structure allowing for simple demodulation and modulation by means of Fast Fourier ransform (FFT) and inverse FFT, respectively. The FFT algorithm is well optimized for computing blocks of samples with power of two sizes, i.e. 2048, 8096, etc. However, to allow simple equalization procedures and avoid interblock interference, a guard interval (GI) has to be appended to the OFDM block. GI reduces the efficiency of the transmission, because it is discarded at the receiver. The first part of this thesis proposes a receiver structure which takes advantage of the GI to improve data detection exploiting the redundancy of the signal. The performance of this structure is then analyzed comparing it with other two structures in a simulation scenario arisen from DVB-T2 reception configurations. The impact of low-density parity check codes (LDPC) which are part of the standard is also outlined. The second part of the thesis focuses on the channel estimation which is the basis for most of the signal processing techniques involved in the reception of an OFDM signal. In particular we focus on channel estimation using known pilot symbols. Transmission of pilot symbols on a sub-set of subcarriers in an orthogonal frequency division multiplexing system allows for an efficient channel estimation at the receiver by means of the Least-Square (LS) method. Usually, for these systems channel estimation is performed on pilots and then interpolated over the time and the frequency axis. We propose to improve the LS estimate on pilots by filtering the estimated channel both across the subcarriers and across different OFDM blocks, with adaptive filters in order to exploit the inter-carrier correlation and reduce the noise on the stimate. We consider various adaptive techniques to let the filter track the time-varying channel conditions: least mean square and Kalman filter theory are applied to design the finite impulse response filters. Besides, also infinite impulse response filters have been designed. Aim of the design is to obtain simple structures suitable for large FDM blocks and receivers with limited computational/memory resources, while still being adaptive to time-varying channel conditions. However, while most pproaches consider a single smoothing filter over time-interpolated estimates, i.e. after time interpolation, we propose the innovative use of multiple adaptive filters that take into account the different correlation among pilot estimates and interpolated estimates. In other words, we propose to design multiple adaptive frequency filters to perform frequency filtering in order to decrease the degree of noisiness of the time-interpolated samples. The idea is to leverage the fact that time-interpolated estimates have different reliability with respect to pilot LS estimates, and thus weighting accordingly the estimates during filtering, performance can be improved. Moreover, as a simpler approach we consider also the use of a single adaptive filter updated taking into account the reliability of the various estimates. Performance results are reported with reference to the DVB-T and DVB-T2 standards showing that the proposed multiple filters technique performs similar or better than existing approaches at a much lower complexity. Although these techniques have been developed considering the DVB-T/T2 pilot patterns, they can be applied to whatever system using pilot-patterned OFDM symbols. The last part of the thesis deals with the initial signal ynchronization for DVB-T2. In fact, the new standard for DTT provides a specific symbol, called P1 symbol, to ease initial signal acquisition and synchronization. We revise a synchronization technique based on the correlation of parts of the received signal showing that it fails to synchronize in practical channel conditions, e.g. single-frequency network (SFN) channels. Hence, we first propose a modified version of the existing technique to better exploit the correlation signal, then we analytically derive the maximum likelihood (ML) time and carrier frequency offset synchronization function. Unfortunately, the maximization of the likelihood function requires numerical methods, therefore we decided to simplify the scheme by considering a ML time (MLT) synchronization scheme, while resorting to a suboptimal estimator for carrier frequency offset (CFO). The proposed schemes are compared with existing solutions on both flat and frequency selective channels typically encountered in DVB-T2 transmissions, showing that both ML and MLT approaches are able to achieve synchronization with probability higher than 99%. The last chapter collects all the simulation results supporting the topics covered in the previous chapters.
La tesi discute tre tra le principali operazioni svolte da un ricevitore per segnali OFDM: i) sincronizzazione di simbolo e di frequenza, ii) stima di canale e iii) demodulazione del segnale. Dal momento che la modulazione OFDM è adottata in molti sistemi diversi, ognuno dei quali fa fronte agli stessi problemi con tecniche caratteristiche, gli argomenti proposti assumono un carattere molto generale. In questo lavoro, perciò, si tratteranno alcune tecniche OFDM applicate agli standard di diffusione terrestre della televisione digitale. La radiodiffusione terrestre della TV digitale ha come standard più diffuso in ambito mondiale il DVB-T. Il sistema è basato sulla trasmissione di un flusso audio/video della famiglia MPEG-2, mediante modulazione OFDM. Recentemente, nel Marzo 2006, il desiderio di migliorare la qualità del servizio, e migliorare la potenza del sistema televisivo hanno stimolato il gruppo DVB a studiare delle nuove opzioni per il miglioramento dello standard DVB-T. Nel 2007 è iniziata l’opera di standardizzazione del nuovo sistema. Dopo due anni, nel 2009, è stato pubblicato lo standard del sistema DVB-T di nuova generazione, che ha preso il nome di DVB-T2. Test sul campo hanno dimostrato che la nuova tecnologia, ancora basata su OFDM, può garantire un incremento di capacità del 30% in più rispetto al sistema precedente. I primi a trasmettere secondo la modalità DVB-T2 sono state alcune reti inglesi. Tuttavia, benché BBC, ITV1 e Channel 4, trasmettessero già in DVB-T2 su uno o due canali, nell’Ottobre 2010, l’emittente televisiva italiana Europa 7 ha lanciato il suo bouquet di 12 canali che trasmettono con tecnologia DVB-T2, divenendo di fatto il primo broadcaster al mondo a trasmettere esclusivamente in DVB-T2. Nel Novembre 2010, i 14 paesi componenti la comunità dei paesi Sud-Africani ha selezionato DVB-T2 come standard di diffusione televisivo della regione. La comunità prevede di operare lo switch-over digitale indicativamente nel Dicembre 2013. Come già abbiamo detto, entrambi gli standard DVB-T hanno scelto OFDM come schema di modulazione. Infatti, il largo utilizzo dell’OFDM si deve alla sua praticità di utilizzo, dovuta alla possibilità di realizzare modulatori e demodulatori a ridotta complessità. Le operazioni di demodulazione e modulazione sono realizzate rispettivamente tramite Trasformata di Fourier (FFT) e la sua operazione inversa (IFFT). FFT e IFFT sono entrambe realizzate mediante lo stesso algoritmo che è ottimizzato per operare su blocchi di campioni di lunghezza pari alle potenze di due, per esempio 2048 e 8096. Comunque, per permettere la realizzazione di procedure semplici di equalizzazione e quindi evitare l’interferenza tra simboli successivi, un Intervallo di Guardia (GI) deve essere trasmesso prima del blocco OFDM. Il GI riduce l’efficienza di trasmissione, in quanto è subito scartato dal ricevitore. La prima parte di questa tesi propone una struttura per il ricevitore che permetta di usare il GI per migliorare la decodifica dei dati. Le prestazioni di questa struttura sono analizzate confrontandola con altre due strutture in uno dei possibili scenari per il DVB-T2. Successivamente, è anche valutato l’impatto dei codici LDPC sulle prestazioni della struttura proposta. La seconda parte della tesi si concentra sulla stima di canale, che in molti casi rappresenta la base per le tecniche di elaborazione di segnale utilizzate nella ricezione di un segnale OFDM generico. In particolare noi consideriamo la stima di canale per sistemi OFDM che utilizzano delle portanti note al ricevitore. La trasmissione di simboli pilota in un sottoinsieme di portanti in un sistema OFDM permette di ottenere una efficiente stima di canale Least Square (LS) al ricevitore. Per questi sistemi la stima di canale è realizzata prima sulle portanti pilota, e successivamente interpolata nel tempo e in frequenza. In questo lavoro si propone di migliorare la stima LS sulle portanti filtrando la stima di canale con dei filtri adattativi. L’operazione di filtraggio è realizzata prima tra simboli OFDM successivi e poi tra portanti di un medesimo simbolo, in modo da sfruttare le correlazioni tra i diversi campioni stimati e ridurre così il livello di rumore. Si sono considerati diverse tecniche adattative per permettere ai filtri di seguire le condizioni di tempo-varianza del canale. Sono state applicate le teorie sui filtri least mean square e Kalman, per progettare filtri a risposta impulsiva limitata o infinita. Lo scopo degli algoritmi adattativi sviluppati è di ottenere delle strutture semplici, in grado di operare su simboli OFDM di grandi dimensioni, e con ricevitori con limitate risorse in termini di potenza di calcolo e memoria. Comunque, mentre molte tecniche considerano un singolo filtro per operare nel dominio della frequenza, cioé dopo l’interpolazione temporale, questa tesi propone l’utilizzo innovativo di più filtri che tengano in considerazione le diverse statistiche di correlazione tra le stime ottenute sulle portanti pilota e quelle ottenute tramite interpolazione temporale. In altre parole, si è proposto di progettare in parallelo più filtri adattativi, ognuno che operi su un sottoinsieme indipendente di portanti. L’idea è quella di sfruttare il fatto che le stime ottenute per interpolazione temporale hanno un’affidabilità diversa rispetto alle stime ottenute con il metodo LS, e quindi pesando le correlazioni in modo appropriato, al momento della procedura di filtraggio adattativo, è possibile un miglioramento delle prestazioni di stima. I risultati sono riportati con riferimento agli standard DVB-T e DVB-T2, dimostrando che la tecnica proposta è competitiva, o addirittura migliore, rispetto alle tecniche utilizzate in precedenza, permettendo una riduzione sostanziale della complessità di calcolo. Sebbene i risultati siano presentati con riferimento agli standard televisivi, queste tecniche possono essere applicate a qualsiasi sitema che utilizzi una modulazione OFDM con portanti pilota note al ricevitore. L’ultima parte della tesi si occupa di sincronizzazione del segnale DVB-T2. Lo standard DVB-T2 definisce un simbolo specifico, detto simbolo P1, per facilitare l’acqusizione iniziale del segnale e la sincronizzazione. In questa parte della tesi si rivisita la tecnica di sincronizzazione basata su correlazione delle parti ridondanti del segnale ricevuto, definita nelle linee guida dello standard. Dopodiché si mostra che essa fallisce quando certe configurazioni reali di canale si presentano, per esempio nel caso di canale caratteristico di una single-frequency network (SFN). Perciò, prima si propone una versione modificata della tecnica base che sfrutti meglio la correlazione del segnale, successivamente si ricava l’espressione analitica della funzione di massima verosimiglianza (ML) per la sincronizzazione di tempo e frequenza. Sfortunatamente non è possibile trovare una forma analitica dello stimatore ML che massimizza la funzione di massima verosimiglianza, perciò è stato introdotto uno schema semplificato che considera la stima ML solo del tempo (MLT), lasciando la stima dell’offset di frequenza ad uno stimatore sub-ottimo. Gli schemi proposti sono confrontati con soluzioni pre-esistenti sia con canali selettivi in frequenza che non. I risultati mostrano che sia la tecnica ML, che la tecnica MLT, sono in grado di raggiungere una corretta sincronizzazione con una probabilità maggiore del 99%. Infine, l’ultimo capitolo raccoglie i risultati di tutte le simulazioni delle tecniche trattate nei capitoli precedenti.

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Conselho Nacional de Pesquisa e Desenvolvimento Cient?fico e Tecnol?gico - CNPq
Digital Video Broadcasting ? Satellite Generation 2 (DVB-S2) standard is widely adopted for militar and civil communication. Due to the long distance between transmitter and receiver, satellite communication links operate with low signal to noise ratio. Forward Error Correction (FEC) techniques are of particular importance for DVBS2 systems, ensuring the desired performance. This dissertation presents the development of a core, in hardware description language, of a LDPC (Low-Density Parity-Check) codec compatible with the DVB-S2 standard. The developed core operates with two sizes of frames and twenty-one encoding rates, as defined in the DVB-S2 standard. The dissertation addresses the main challenges regarding the codec implementation and how they are faced. Three versions of the proposed architecture are implemented and evaluated. Each version uses a different numerical representation for the codec variables. VHDL simulation results are compared with simulations in C programming language, which uses floating point. The results show that the proposed core has equivalent or superior performance to those works reported in the literature when using the architecture with the smallest numerical representation. However, when evaluated the architecture with the highest numerical representation, the obtained FEC performance is significantly better than those presented in the literature, and are close to the results obtained with 64 bits floating point representation. In addition to the performance evaluation, the use of the FPGA (Field-Programmable Gate Array) resources are presented for each one of the three implemented architectures. The analysis of performance versus FPGA resources is addressed.
O padr?o Digital Video Broadcasting ? Satellite Generation 2 (DVB-S2) ? amplamente utilizado em comunica??es via sat?lite, para opera??es nas ?reas de defesa e de comunica??o civil. Devido ? dist?ncia entre transmissor e receptor, enlaces de comunica??o via sat?lite operam com baixa rela??o sinal-ru?do. T?cnicas de Forward Error Correction (FEC) s?o de particular import?ncia no desempenho de sistemas DVB-S2, garantindo a performance desejada. Esta disserta??o de mestrado apresenta o desenvolvimento de um core, em l?gica program?vel, de um codec LDPC (Low-Density Parity-Check) compat?vel com o padr?o DVB-S2. O core opera com os dois tamanhos de frames e as vinte e uma taxas de codifica??o previstas no padr?o. A disserta??o aborda os principais desafios de implementa??o do codec em hardware e como os mesmos s?o enfrentados. Tr?s vers?es da arquitetura proposta s?o implementadas e avaliadas, utilizando diferentes representa??es num?ricas das vari?veis do sistema, em ponto fixo. Os resultados de simula??o do core VHDL s?o balizados atrav?s de simula??es em linguagem de programa??o C, utilizando ponto flutuante. Os resultados obtidos demonstram que o core proposto apresenta desempenho equivalente ou superior aos relatados em literatura quando utilizada a menor representa??o num?rica implementada. No entanto, quando avaliada a arquitetura de maior representa??o num?rica, os resultados do core proposto nesta disserta??o s?o significantemente superiores aos apresentados em literatura, e pr?ximos aos resultados obtidos nas simula??es em C, utilizando representa??o de 64 bits em ponto flutuante. Al?m das avalia??es de desempenho, s?o apresentados os recursos de hardware utilizados para cada uma das tr?s implementa??es propostas, sendo realizada a an?lise quanto a desempenho versus ocupa??o de recursos FPGA (Field-Programmable Gate Array).

In this thesis, a single carrier ATSC DTV baseband transmitter, part of the receiver(including channel estimator and channel equalizer), were modeled. Since multi-pathinduced ISI (inter symbol interference) is the most significant impact on theperformance of single carrier DTV reception, modeling and implementation of singlecarrier channel estimator and channel equalizer have been the focus of the thesis. Westarted with the investigation of channel estimation methods. Afterwards, severalchannel estimators and equalizers were modeled and the performance of each channelequalization methods in different scenarios was evaluated. Our results show that thefrequency domain equalizer can achieve low computing cost and handle long delaypaths. Another important issue to be considered in block equalization is Inter-BlockInterference (IBI). The impact of IBI was investigated via behavior modeling. In lastpart of our thesis, two methods for IBI cancellation are compared and the proposal forhardware implementation was given.

In digital video broadcasting, sometimes many sources are used. When handling this broadcast a problem is a limited interface that has a fixed number to input channels but overcapacity in data transfer rate. To be able to connect more inputs to the interface a protocol that lets the user send more than one channel on a connection is needed. The important part for the protocol is that it keeps the input equal to the output both in timing and in what data is sent. These are done by encapsulating the data and use a header containing information for recreating the input. To solve the timing constraint dynamic buffer are used that makes all data evenly delayed. To validate the functionality of the protocol a test designed is implemented in VHDL and simulated.

The purpose of this thesis is to detect errors in Digital Multimedia Broadcasting (DMB) transport stream. DMB uses the MPEG-4 standard for encapsulating Packetized Elementary Stream (PES), and uses the MPEG-2 standard for assembling them in the form of transport stream packets. Recently many research works have been carried out about video stream error detection. They mostly do this by focusing on some decoding parameters related to frame. Processing complexity can be a disadvantage for the proposed methods. In this thesis, we investigated syntax error occurrences due to corruption in the header of the video transport stream. The main focus of the study is the video streams that cannot be decoded. The proposed model is implemented by filtering video and audio packets in order to find the errors. The filters investigate some sources that can affect the video stream playback. The output from this method determines the type, location and duration of the errors. The simplicity of the structure is one of advantages of this model. It can be implemented by three simple filters for detecting errors and a “calculation unit” for calculating the duration of an error. Fast processing is another benefit of the proposed model.

Estando prevista a introdução da televisão digital terrestre em Portugal para os próximos anos, coloca-se o desafio de projectar o seu desenvolvimento, sendo os aspectos do planeamento de frequências e da cobertura fundamentais para a concepção de um sistema a nível nacional. Dado que em Portugal se irá utilizar Coded Orthogonal Frequency Division Multiplexing (COFDM) 8K (6817 portadoras), com alcances máximos de cerca de 67 km por estação transmissora, neste trabalho, para além de se abordarem os aspectos globais da norma Digital Video Broadcast (DVB) e das suas variantes terrestre, por cabo, via satélite e móvel, abordam-se sistemas de difusão terrestres em particular, identificando-se as características do sistema que terão um forte impacto no planeamento, aspectos de cobertura DVB-T, atribuição e planeamento de frequências e ferramentas gráficas de planeamento recorrendo a sistemas de informação geográfica (SIG). Obtiveram-se resultados do planeamento de uma rede DVB-T em SFN no modo 8K com COFDM em modulação 64-QAM para a área geográfica da Beira Interior, utilizando uma frequência que irá ficar disponível após o “switcth-off”. A tecnologia DVB dá um grande contributo para que no futuro se ocupe menos espectro radioeléctrico com mais e melhores serviços que os prestados actualmente com tecnologia analógica, tal contributo só é possível graças ao desenvolvimento de algoritmos complexos para compressão de vídeo e áudio a transmitir. No planeamento da rede DVB-T Beira Interior chega-se à conclusão que o número de emissores e potências utilizadas são menores, comparando com o sistema analógico actual, conseguindo-se uma cobertura boa de 87% da população, cobertura aceitável de 95% da população e cobertura portátil interior na cidade da Covilhã.
As the introduction of terrestrial digital TV in Portugal is foreseen for the next years, the endeavour of designing its development needs to be faced, and the aspects of frequency and coverage are essential for the conception and deployment of a system with national availability. As in Portugal the option is to use Coded Orthogonal Frequency Division Multiplexing (COFDM) 8K (6817 carriers), with maximum coverage ranges per Station around 68 km, in this work, besides the general aspects of Digital Video Broadcast (DVB) and its terrestrial, cable, satellite and mobile variants, one specifically addresses terrestrial broadcast systems in particular. The characteristics with the strongest impact in the planning process are identified, as well as DVB-T coverage aspects, frequency assignment and planning, and geographical information systems graphical planning tools issues (GIS). Planning results were obtained for a DVB-T OFDM based network operating at Single Frequency Network (SFN), 8K mode, with 64-QAM modulation. The Beira Interior region was considered, and the frequency band that will be available for this Portuguese region after Switch-off of analog TV was considered. DVB gives a strong contribute to the reduction of spectrum wastage in the television broadcast sector while providing more and better services support in comparison to analog TV. This advantage is only possible owing to the development of complex algorithms for the compression of video and audio content to be transmitted. In the region of Beira Interior, Portugal, the number of transmitting stations and the transmitter powers are clearly lower than the ones for the today analog TV system. The following follows were achieved for the actual coverage of the population: “good” coverage of 87% of the population, acceptable coverage of 95% of the population and portable indoor coverage within the city of Covilhã.

There has been a significant rise in the provision of television and video services over IP (IPTV) in recent years. Increasing network capacity and falling bandwidth costs have made it both technically and economically feasible for service providers to deliver IPTV services. Several telecommunications (telco) operators worldwide are rolling out IPTV solutions and view IPTV as a major service differentiator and alternative revenue source. The main challenge that IPTV providers currently face, however, is the increasingly congested television service provider market, which also includes Internet Television. IPTV solutions therefore need strong service differentiators to succeed. IPTV solutions can doubtlessly sell much faster if they are more affordable or low-cost. Advertising has already been used in many service sectors to help lower service costs, including traditional broadcast television. This thesis therefore explores the role that advertising can play in helping to lower the cost of IPTV services and to incentivise IPTV billing. Another approach that IPTV providers can use to help sell their product is by addressing the growing need for control by today's multimedia users. This thesis will therefore explore the varied approaches that can be used to achieve viewer focused IPTV implementations. To further lower the cost of IPTV services, telcos can also turn to low-cost, open source platforms for service delivery. The adoption of low-cost infrastructure by telcos can lead to reduced Capital Expenditure (CAPEX), which in turn can lead to lower service fees, and ultimately to higher subscriptions and revenue. Therefore, in this thesis, the author proposes a CustOmisable, INcentive (COIN) driven Video on Demand (VoD) framework to be developed and deployed using the Mobicents Communication Platform, an open source service creation and execution platform. The COIN framework aims to provide a viewer focused, economically competitive service that combines the potential cost savings of using free and open source software (FOSS), with an innovative, incentive-driven billing approach. This project will also aim to evaluate whether the Mobicents Platform is a suitable service creation and execution platform for the proposed framework. Additionally, the proposed implementation aims to be interoperable with other IPTV implementations, hence shall follow current IPTV standardisation architectures and trends. The service testbed and its implementation are described in detail and only free and open source software is used; this is to enable its easy duplication and extension for future research.
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For centuries, repetition in one form or another has been seen as a significant element in the artistic palette. In numerous formats of expression, duplication and looping became a significant tool utilized by artisans in a multitude of creative formats. Yet within the realm of film, the Griffith and Eisenstein models of cinematic editing techniques (as the most popular-- and near-monolithic--narrative aesthetic criteria) effectively disregarded most other approaches, including looping. Despite the evidence for the consistent use of repetition and looping in multiple ways throughout the course of cinematic history, some theorists and practitioners maintain that the influx of the technique within digital cinema in recent years represents a sudden breakthrough, one that has arrived simply because technology has currently advanced to a point where their utilization within digital formats now makes sense both technologically and aesthetically. This situation points to a cyclical problem. Students of film and video frequently are not taught aesthetical or editorial options other than standard industry procedures. Those who are interested in varying techniques are therefore put in the position of having to learn alternative practices on their own. When they do look beyond visual norms to try applying different approaches in their projects, they risk going against the views of their instructors who are only interested in implementations of the standard methods which have been in the forefront for so long. Yet the loop s importance and prevalence as a digital language tool will only likely grow with the evolution of digital cinema. With this is mind, the dissertation addresses the following questions: To what extent can various forms of repetitive visuals be found throughout film history, and are not simply technical manifestations that have merely emerged within digital cinema? How might current educational practices in the realm of film and video work to inform students of techniques outside of the common narrative means? Finally, what other sources or strategies might be available to enlighten students and practitioners exploring both the history surrounding--and possible applications of--techniques based upon early cinema practices such as the loop?
Ph.D.
Department of English
Arts and Humanities
Texts and Technology PhD

La diffusion de signaux de télévision numérique est soumise à un certain nombre de contraintes. Notamment les niveaux de rayonnements non essentiels (RNE) émis en dehors des fréquences d’émission doivent être inférieurs à un seuil fixé par les instances de régulation afin de ne pas brouiller les autres canaux de diffusion. Compte tenu du caractère non-linéaire des amplificateurs de puissance, l’augmentation de la puissance diffusée permet d’augmenter le rendement des amplificateurs mais augmente en même temps le niveau des RNE. Les diffuseurs doivent donc trouver un compromis entre le niveau des RNE émis et le coût de revient des équipements de diffusion. Jusque là, les programmes DVB-T sont amplifiés en monocanal, c’est-à-dire que chaque multiplex est amplifié par un amplificateur. Le rendement est optimisé en utilisant un précorrecteur numérique afin de limiter les intermodulations dans le canal et dans les canaux adjacents, et en utilisant un filtre de canal afin de nettoyer le spectre. Cette technique de précorrection numérique, simulée dans ce mémoire, permet effectivement d’améliorer les shoulders et le TEB. L’amplification multicanal permettrait un gain important car un seul amplificateur est nécessaire pour traiter plusieurs multiplex. Cependant sans linérisation, il est nécessaire d’utiliser l’amplificateur de puissance avec un recul de puissance très élevé pour que le seuil maximal des RNE ne soit pas atteint. Nous proposons ici un précorrecteur multicanal qui permet de diminuer Digital television broadcasting is subjected to a certain number of contraints
Among others, the spurious levels must be lower than the threshold imposed by regulation authorities to avoid disturbing the other channels. Taking in account the non linearity nature of power amplifiers, increase the emitted power leads to increase the efficiency but also the spurious level. Consequently, broadcasters should reach a compromise between spurious level and transmitters cost. DVB-T programs are currently amplified in mono-channel, i. E. Each multiplex is amplified by its own amplifier. The efficiency is improved using a digital predistorter and a band-pass filter. The digital predistorter minimizes in band and out of band intermodulations, and the filter cleans the spectrum. The digital predistortion method, simulated in this memory, allows a great improvement of the shoulders and the BER. Multi-channel amplification would conduce to a high profit because only one amplifier is necessary to treat several channels. However without linearization, the amplifier must be used with a very high output back-o? in order to keep the spurious level below the fixed threshold. In this thesis we present a multi-channel predistorter that highly improves the shoulders and the spurious level

The inherent broadcast nature of satellites, their global coverage and direct access to a large number of subscribers give satellites unrivalled advantages in supporting IP multicast applications. A new generation of satellite systems that support regenerative on-board processors and multiple spot beam technology have opened new possibilities of implementing IP multicast communication over satellites. These new features enable satellites to make efficient use of their allocated bandwidth resources and provide cost effective network services but equally, create new challenges for mobile satellite terminals. IP mobility support in general and IP mobile multicast support in particular on mobile satellite terminals like the ones mounted on continental flights, maritime vessels, etc., still remain big challenges that have received very little attention from the research community. Up till now, there are no proposed mechanisms to support IP multicast for mobile receivers/sources in multi-beam satellite networks in open literature. This study explores the suitability of IP multicast mobility support schemes defined for terrestrial networks in a satellite environment and proposes novel schemes based on the concepts of Home and Remote subscription-based approaches, multiple interface and PMIPv6 protocol. Detailed analysis and comparison of results obtained from the proposed schemes, Mobile IP (MIP) Home and Remote subscription-based approaches (for terrestrial networks) when implemented on a reference multi-beam satellite network are presented. From these results, the proposed schemes outperform the MIP Home and Remote subscription-based approaches in terms of gateway handover latency, number of multicast packets lost and signalling cost over the satellite air interface.

The inherent broadcast nature of satellites, their global coverage and direct access to a large number of subscribers give satellites unrivalled advantages in supporting IP multicast applications. A new generation of satellite systems that support regenerative on-board processors and multiple spot beam technology have opened new possibilities of implementing IP multicast communication over satellites. These new features enable satellites to make efficient use of their allocated bandwidth resources and provide cost effective network services but equally, create new challenges for mobile satellite terminals. IP mobility support in general and IP mobile multicast support in particular on mobile satellite terminals like the ones mounted on continental flights, maritime vessels, etc., still remain big challenges that have received very little attention from the research community. Up till now, there are no proposed mechanisms to support IP multicast for mobile receivers/sources in multi-beam satellite networks in open literature. This study explores the suitability of IP multicast mobility support schemes defined for terrestrial networks in a satellite environment and proposes novel schemes based on the concepts of Home and Remote subscription-based approaches, multiple interface and PMIPv6 protocol. Detailed analysis and comparison of results obtained from the proposed schemes, Mobile IP (MIP) Home and Remote subscription-based approaches (for terrestrial networks) when implemented on a reference multi-beam satellite network are presented. From these results, the proposed schemes outperform the MIP Home and Remote subscription-based approaches in terms of gateway handover latency, number of multicast packets lost and signalling cost over the satellite air interface.

Os sistemas de telecomunicações sem fios dependem fundamentalmente do espectro de frequências radioeléctrico. Actualmente, os estudos dos organismos reguladores indicam que a utilização do espectro com licenciamento fixo é subaproveitada e que existe o problema da escassez de oferta do espectro. Assim, com o aumento da procura de novos serviços e do número de utilizadores os operadores de telecomunicações têm por obrigação de procurar novas soluções, que visem o aumento da eficiência espectral através de técnicas avançadas de processamento para a gestão do espectro. Esta dissertação propõe a operação do LTE em frequências mais baixas (UHF) para o aumento da eficiência espectral em conjunto com a gestão do espectro de rádio com atribuição temporária, no contexto da inter-coexistência. Assim, a transição da televisão analógica para a TDT oferece uma nova oportunidade no aproveitamento das bandas UHF para o aumento da oferta por parte dos operadores de telecomunicações. Em particular, os canais nas bandas UHF são adequados para aplicações móveis, devido às suas excelentes condições de propagação e penetração (superior) em edifícios. Além disso, o comprimento de onda nestas bandas é suficientemente curto, permitindo construir antenas com um tamanho adequado para uso portátil. Como possibilita a cobertura eficiente por parte dos operadores de telecomunicações de vastas áreas geográficas com um menor número de estações base. Assim sendo, a atribuição temporária de espectro nas bandas de TV (espaços vazios da TV, TV White Spaces - TVWS) com direitos exclusivos temporários é muito valiosa. Dado que os TVWS estarão disponíveis em 2012, as bandas utilizadas são um sério candidato para suportar o sistema LTE. As vantagens da utilização do sistema LTE são a flexibilidade em operar em várias bandas de frequência e em várias larguras de banda. No entanto, a maioria dos países europeus pensa utilizar a frequência 2.6 GHz para o sistema LTE o que poderá limitar a sua cobertura e diminuir o seu desempenho. Assim, através da utilização temporária das portadoras LTE nos TVWS (700MHz) poderá obter-se uma capacidade extra em redes próximas da saturação ou de cobertura melhorada. Para se observarem as diferenças entre a utilização dos 2.6GHz e os 700 MHz desenvolveu-se um simulador de LTE em MATLABTM, numa linguagem script orientada a objectos. O simulador permite obter resultados de cobertura e capacidade nas frequências actuais (Legacy) e nos TVWS. No processo de atribuição dinâmico dos recursos do LTE, o simulador utiliza dois algoritmos de Radio Resource Management (RRM), no contexto de Multi Band Access (MBA). Um dos algoritmos atribui recursos das duas bandas de forma equilibrada enquanto a outra dá prioridade a um das bandas, originado numa utilização mais eficiente dos recursos disponíveis. O objectivo é maximizar a utilização dos TVWS na atribuição dinâmica do espectro e minimizar a fragmentação do espectro, mantendo-se a QoS e evitar interferências entre os sistemas secundários e primário.
The wireless systems are dependent of the electromagnetic spectrum. The studies from the regulatory bodies show that, with a permanent licensing, the spectrum is underused; and there exists a shortage in the spectrum availability. Therefore, with the introduction of new services and the growth in the number of subscribers, operators face a new challenge and must find engineering solutions to increase the spectral efficiency and manage the available spectrum. This thesis purposes the extension of LTE operation over low frequency bands (UHF) in order to increase the spectral efficiency in conjunction with temporary use of the available spectrum, in the context of inter-coexistence. Hence, the transition to digital TV (i.e., digital TV switch-over) represents an opportunity to re-use UHF band with the respective increase in the operator's services offers. Namely, the UHF band is considered valuable for mobile services due to its excellent propagation characteristics and penetration through walls. Besides, the wavelength in this band is small enough to allow the construction of antennas that can be used in mobile devices. Additionally, in this band, the cell radius is larger than in upper frequencies (due to the lower path loss) which allow for operators to cover larger areas with less base stations. Therefore, the licensing process to use frequency spectrum in the TV bands for mobile services with temporary exclusive rights is seen to be very valuable. These channels are known as TV white spaces (TVWS). Since TVWS will be available in 2012, they are a serious candidate to support the LTE standard. The advantages of LTE are related with the flexibility to operate in different frequencies with various bandwidths. However, most of the European countries intent to use the 2.6 GHz frequency for LTE networks, which may limit the system's coverage and performance. Hence, with the use of temporary LTE carriers in TVWS (700MHz) it is possible to achieve extra capacity in networks near the saturation point and/or with ameliorated coverage. For this purpose, in order to evaluate the differences in terms of performance between LTE networks at 2.6 GHz and 700 MHz, a simulator was developed using a script language in MATLABTM . The simulator enables to achieve results about the coverage and capacity in the actual Legacy frequencies as well as in TVWS. In the dynamic process of distributing the LTE radio resources, two algorithms were used for Radio Resource Management (RRM), in a Multi Band Access (MBA) context. One of the algorithms try to equally distribute the resources while the other prioritize one of the bands against the other, lending to a more efficient use of available resources. The objective is to maximize the use of TVWS and minimize the fragmentation of the spectrum while keeping the comparable QoS levels.

El objetivo principal del proyecto de tesis doctoral es proponer y evaluar soluciones técnicas compatibles con la familia de estándares DVB diseñados para redes TDT que permitan por un lado, la transmisión simultánea de contenidos de TV a receptores fijos y móviles en configuraciones de red con alta capacidad de transmisión, y por otro lado la e ficiente provisión de contenidos locales en topologías SFN. Esta propuesta de tesis está dividida en tres secciones. La primera sección consiste en una revisión del estado del arte respecto a la planificación y diseño de redes de TDT que utilizan los estándares DVB, las soluciones propuestas e implementadas a día de hoy para la provisión de contenidos de TV digital a terminales móviles a través de las infraestructuras de TDT; así como las técnicas de transmisión utilizadas para la provisión de contenidos locales en redes de TDT, las soluciones propuestas en el estándar de segunda generación DVB-T2 y los requerimientos técnicos del futuro estándar DVB-NGH para la e ficiente emisión de estos contenidos en topologías de red SFN. Con base en el estado del arte se de ne en la segunda sección el objetivo principal, los objetivos específicos y los resultados esperados en el desarrollo de la tesis doctoral. Finalmente en la tercera sección se describe la metodología y los escenarios de evaluación que se utilizarán en las diferentes etapas del proceso de investigación.
López Sánchez, J. (2014). Transmisión Eficiente de Servicios Fijos/Móviles y Servicios Locales en Redes de Televisión Digital Terrestre de Primera y Segunda Generación [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/35134
TESIS

Digital Video Broadcasting (standard DVB) is a system for transmission of the television signals in the digital form. There are used a various types of modulations in this system as QPSK modulation is used in the systems of satellite video broadcasting DVB-S (Satellite) and M-QAM modulations in the cable transmitting DVB-C (Cable). This paper mainly deals with system of the terrestrial digital video broadcasting DVB-T (Terrestrial), where OFDM modulation is used. This type of signal processing is more resistant to the distortions caused by multipath transmitting, which is main problem in the DVB-T. Matlab application, which can simulate digital modulation and demodulation of the transmission signals in the DVB-T, is created in this thesis. The models of the transmission channel is inserted between structures of modulator and demodulator. The user of this application can set the parameters of the broadcasting (e.g. constellation, OFDM mode, guard interval insertion) and the type of distortions (additive noise, reflected and delayed signals). By calculation of the channel bit error rate (BER) user can study influences of broadcasting parameters to the quality of transmission.

The main goal of this dissertation is to study the Xlet-based interactive applications (such as advertisements, games, government services and early warning applications) in the digital television broadcasting environment and to improve their versatility, usability and interoperability through the simplification of their codes and content management methods. The EU had set an obligation for its member states to begin digital television broadcasting by 2012, therefore the development of such systems prior to this deadline had become a task of utmost importance in recent years. At present, there are two major systems of digital video broadcasting (DVB), which are DVB-HTML and DVB-J (DVB-Java). I decided to give more emphasis on DVB-J for my research, mainly because it’s more compatible with the interactive applications that are created with Java-based Xlets, and also because it’s easier to use, modify and update; hence the reason why DVB-J is the system that’s preferred by a larger number of television broadcasting corporations worldwide. DVB-J is also the digital video broadcasting standard that’s compatible with a larger number of MHP (Multimedia Home Platform, or DVB-MHP) systems that are utilized by the set-top-boxes for receiving interactive content (in the form of Xlets) during digital television broadcasts; as well as by handheld devices and web-based internet television networks. As of today, Italy (which has a large and expanding DVB-T network) is one of the leading countries in the world that extensively utilize DVB-MHP systems for sending and receiving interactive content during IDTV broadcasts. By 2009, several administrative regions in Italy had already completed the switch-off process of their analog broadcasting systems and had gone all-digital. Numerous interactive services are currently available in the IDTV broadcasting environment of Italy, ranging from IDTV-commerce and IDTV-government services to the use of a growing number of internet content. At present, the terrestrial antennas for sending the aerial digital signals of the DVB-T networks aren’t capable of receiving any return signals for interaction by mobile handsets like the DVB-H, therefore interactivity is currently limited to internet connection through DSL in stationary devices or to mobile telephone services in the outdoor environments. Internet connection, however, allows the interoperability between different types of stationary and mobile devices, such as television sets, PCs, notebook computers, mobile phones, DVB-H, BlackBerry and iPod. Due to the complexities which arise from the burden of having to provide an efficient and safe interoperability between an ever-increasing number of different device types, I based my research on developing a CMS that’s simple, flexible and easy to upgrade. Since Xlets are Java applets that are developed for digital television broadcasting, I have so far concentrated on the utilization of Java TV API in platforms that are capable of receiving digital and interactive content, such as TV set-top-boxes, DVB-H, and the latest generation of cell phones. In order to optimize the use of such digital and interactive content, which become more diffused and complex through constant innovations, it is necessary to develop an IESG (Integrated Electronic Service Guide) system, due to the ever-increasing traffic of digital and interactive content. The IESG is particularly effective in categorizing the contents and optimizing their availability to the users through a more sensitive search which yields better results, thus saving both bandwidth and user time. In the following chapters, I have explained the methods that I used for the creation of simple and quick (optimized in terms of downloading and running time) Xlets for the IDTV broadcasting environment; and the elaboration of a basic and versatile content management system to store and run these Xlet-based applications by a Set-Top-Box, the functions and properties of which are emulated by the XleTView software. The themes that I chose for the Xlets are the Earthquake and Tsunami Early Warning application, the Recent Seismic Activity Report application, and the Emergency Services application.

1. Rohling H. (2011). OFDM Concepts of Future Communication Systems. Springer. doi: 10.1007/978-3-642-17496-42. 2. Chiueh Tzi-Dar. Baseband Receiver Design for Wireless MIMO-OFDM Communications / Tzi-Dar Chiueh, Pei-Yun Tsai, I-Wei Lai 2nd ed. John Wiley & Sons Singapore Pte. Ltd., 2012. 3. Myronchuk, O., Shpylka, O., & Zhuk, S. (2020). Two-stage Channel Frequency Response Estimation in OFDM Systems. Path of Science, 6(2), 1001-1007. doi: http://dx.doi.org/10.22178/pos.55-1 4. Myronchuk O. Algorithm Of Channel Frequency Response Estimation In Orthogonal Frequency Division Multiplexing Systems Based On Kalman Filter / O. Myronchuk, O. Shpylka, S. Zhuk // 2020 IEEE 15th International Conference on Advanced Trends in Radioelectronics, Telecommunications and Computer Engineering (TCSET), Lviv-Slavske, Ukraine, 2020, pp. 31-34, doi: 10.1109/TCSET49122.2020.235385. 5. Мирончук А. Ю. Метод оценивания частотной характеристики канала в OFDM системах на основе фильтрации и экстраполяции пилот-сигналов / А.Ю. Мирончук, А.А. Шпилька, С.Я. Жук // Вестник НТУУ "КПИ". Серия Радиотехника. Радиоаппаратостроение. – 2019. №78. – С. 36 42. doi: 10.20535/RADAP.2019.78.36-42. 6. Шпилька, А. А., & Жук, С. Я. (2010). Совместная интерполяция данных и фильтрация параметров многолучевого канала связи. Известия высших учебных заведений. Радиоэлектроника, 53(1), 26–30. https://doi.org/10.20535/S0021347010010048 7. Shpylka, A.A., Zhuk, S.Y. Decoding of convolutional codes on a sliding window during signal propagation in a multipath communications channel. Radioelectron.Commun.Syst. 53, 497–501 (2010). https://doi.org/10.3103/S0735272710090086 8. Myronchuk O. Yu. Two-Stage Method for Joint Estimation of Information Symbols and Channel Frequency Response in OFDM Communication Systems / O. Yu. Myronchuk, A. A. Shpylka, S. Ya. Zhuk // Radioelectronics and Communications Systems. – 2020. Vol. 63. – No. 8, pp. 418 429. doi: 10.3103/S073527272008004X 9.Луцький М.Г., Корченко О.Г., Горніцька Д.А., Ярмошевич І.М. Модель оцінки якості експерта для підвищення об’єктивності експертиз у сфері інформаційної безпеки. Захист інформації. 2011. Том 13. Вип. 2(51). DOI: 10.18372/2410-7840.13.2022
Orthogonal frequency division multiplexing (OFDM) is widely used in modern digital communication systems such as digital video and audio broadcasting (ISDB-T, DVB-T, DVB-T2, DRM, DAB), wireless broadband networks (IEEE 802.16), local area networks (IEEE 802.11a, g, n), mobile communication systems (LTE, LTE Advanced) and other. The main advantages of OFDM are high spectrum efficiency and possibility to provide high data transmitting speeds.
Мультиплексування з ортогональним частотним поділом (OFDM) широко використовується в сучасних цифрових системах зв'язку, таких як цифрове відео- та аудіомовлення (ISDB-T, DVB-T, DVB-T2, DRM, DAB), бездротових широкосмугових мережах (IEEE 802.16), локальній мережі мережі (IEEE 802.11a, g, n), системи мобільного зв'язку (LTE, LTE Advanced) та інші. Основними перевагами OFDM є висока ефективність спектру та можливість забезпечити високі швидкості передачі даних.

This master’s theses consists of theoretical introduction which includes basic search of referenced literature about digital television systems and picture quality classification. The results of signal character measurement of selected TV channels from satellites ASTRA 1E (DVB-S) and ASTRA 1L (DVB-S2) are provided. The energy budget calculation of downlink and results of 24-hour TS error rate measurement is included as well. The video quality by DVQL metric for each particular program of CS link stream was measured during full 24 hours.

This dissertation considers packet-switched wireless networks for transmission of variable-rate layered hybrid video streams. Target applications are video streaming and broadcasting services. The work can be divided into two main parts.

In the first part, a novel quality-scalable scheme based on coefficient refinement and encoder quality constraints is developed as a possible extension to the video coding standard H.264. After a technical introduction to the coding tools of H.264 with the main focus on error resilience features, various quality scalability schemes in previous research are reviewed. Based on this discussion, an encoder decoder framework is designed for an arbitrary number of quality layers, hereby also enabling region-of-interest coding. After that, the performance of the new system is exhaustively tested, showing that the bit rate increase typically encountered with scalable hybrid coding schemes is, for certain coding parameters, only small to moderate. The double- and triple-layer constellations of the framework are shown to perform superior to other systems.

The second part considers layered code streams as generated by the scheme of the first part. Various error propagation issues in hybrid streams are discussed, which leads to the definition of a decoder quality constraint and a segmentation of the code stream to transmit. A packetization scheme based on successive source rate consumption is drafted, followed by the formulation of the channel code rate optimization problem for an optimum assignment of available codes to the channel packets. Proper MSE-based error metrics are derived, incorporating the properties of the source signal, a terminate-on-error decoding strategy, error concealment, inter-packet dependencies, and the channel conditions. The Viterbi algorithm is presented as a low-complexity solution to the optimization problem, showing a great adaptivity of the joint source channel coding scheme to the channel conditions. An almost constant image qualiity is achieved, also in mismatch situations, while the overall channel code rate decreases only as little as necessary as the channel quality deteriorates. It is further shown that the variance of code distributions is only small, and that the codes are assigned irregularly to all channel packets.

A double-layer constellation of the framework clearly outperforms other schemes with a substantial margin.

Keywords — Digital lossy video compression, visual communication, variable bit rate (VBR), SNR scalability, layered image processing, quality layer, hybrid code stream, predictive coding, progressive bit stream, joint source channel coding, fidelity constraint, channel error robustness, resilience, concealment, packet-switched, mobile and wireless ATM, noisy transmission, packet loss, binary symmetric channel, streaming, broadcasting, satellite and radio links, H.264, MPEG-4 AVC, Viterbi, trellis, unequal error protection

Cette thèse a pour objectif l'analyse du système de télévision numérique chinois (DTMB) et l'optimisation de sa fonction d'estimation de canal. Tout d'abord, une analyse approfondie de ce système est effectuée en comparaison du système DVB-T en termes de spécifications, d'efficacité spectrale et de performances. Ensuite, la fonction d'estimation de canal basée sur la séquence pseudo-aléatoire du système est étudiée dans les domaines temporel et fréquentiel, et plusieurs améliorations sont apportées aux méthodes typiques afin de notamment gérer les canaux très dispersifs en temps. Enfin, de nouveaux procédés itératifs aidés par les données et peu complexes sont proposés pour raffiner les estimés de canal. Les fonctions de décodage de canal et d'entrelacement sont exclues de la boucle et des fonctions de filtrage temps/fréquence sont étudiées pour fiabiliser les estimations. Ces nouveaux algorithmes démontrent leur efficacité par rapport aux méthodes courantes de la littérature.

L’évolution des applications vers le multimédia et des réseaux vers une hétérogénéité d’architectures protocolaires, a placé la notion de Qualité de Service au cœur des architectures de communication émergentes ; Ceci soulève la question de l’expression de la QdS et de l’adaptation aux besoins applicatifs de la diversité des services disponibles. Cette thèse propose un cadre sémantique et syntaxique pour décrire les contraintes applicatives et les services sous-jacents, et sélectionner et composer les services de communication, répondant aux besoins applicatifs. Les systèmes satellitaires intègrent une propriété naturelle de diffusion de l’information, ce qui en fait un composant de l’Internet de nouvelle génération. Nous montrons comment, grâce au cadre générique, les services orientés gestion de QdS spécifiques d’une architecture de communication satellitaire peuvent être composés, afin de délivrer une adaptation efficace entre les ressources satellitaires et les besoins applicatifs.

碩士
中華大學
電機工程學系(所)
96
The digital TV has become a mature and universal technique in recent years. The European standard for digital video broadcasting over terrestrial (DVB-T) has already been adopted by a lot of countries, including Taiwan. In this discussion, we will investigate the digital video broadcasting over terrestrial in Taiwan, and build the Simulink platform of the digital video broadcasting system. Establishes a receiver by the platform receiving, receives the Taiwan wireless television station signal, and decodes the transmission parameter signaling (TPS).

碩士
國立高雄師範大學
物理學系
96
n this thesis, many novel low-cost antenna designs are presented for DVB-T applications. These antennas are designed based on the use of monopole antenna, but with different techniques in order to overcome the narrow-bandwidth problem of conventional monopole antenna. Promising DVB-T antennas showing the omnidirectional radiation patterns and having low-profile configurations are demonstrated.

碩士
高苑科技大學
電機工程研究所
99
Using BER for Digital Video Broadcasting- Satellite (DVB-S) Student: Chi- Nen Hung Advisor : Chin-Ta Chen Abstract This paper is to study the system structure and channel coding of the Digital Video Broadcasting- Satellite (DVB-S). We use signal generator of DVB - S2/ S to be the Simulation DVB-S Source and apply DVS Station3 application software and R&S SFE100 to be the RF signal generator. We simulate and do the objective analysis of the DVB-S system that is combined the quadrature phase shift keying（QPSK）、different Code Rate and symbol Rate. Experimental results show that the best BER in DVB-S system is happened at 1/2 code rate、the worst condition is at 5/6、7/8code rate and 2/3、 3/4 are no obviously variations while RF signal generator (SFE100)、modulator (QPSK)、the different output level 、five kinds of symbol rates and four kinds of code rates are applied to measure the BER performance. These results can prove and practice the DVB-S system.

碩士
國立臺北科技大學
電腦與通訊研究所
95
For mobile receiving, transmitted data may be interfered, polluted and destroyed by the environmental noise easily. The service may be broken in the adverse circumstances. Therefore, it is very import to keep the quality of service (QoS) well from the consumer’s viewpoint. At the receiver of DVB-H, Multi-Protocol Encapsulation Forward Error Correction (MPE-FEC) is used to recover the polluted data. To achieve MPE-FEC by hardware is lacking flexibility, needing long time to verify and costing more funds than software. For this reason, this thesis implements MPE-FEC of DVB-H receiver by software to recover polluted data. In MPE-FEC, to repair the polluted data by Reed-Solomon (RS) Code is all depending on its powerful capability of error correction. This thesis uses Java program language to implement the MPE-FEC in DVB-H terminal. In addition to the information carried in the test file does not sufficient that let the program design more complicated and the complexity of RS decoding are costing much time for decoding transport stream. At last, this thesis also use C/C++ program language and different algorithm for RS decoding on Windows and Linux Operation System for testing. To wish that the experiment result can be the reference documents for development in the future.

碩士
逢甲大學
電子工程所
94
With the advances of science and technology, television broadcasting also moves into the digital era. Therefore, channel coding-decoding is worthy of conferring and researching because it is important for digital television broadcasting systems. The DVB-T published by European Broadcast Union makes use of Reed-Solomon code and viterbi decoder for channel codec. In this thesis we, first at all, compare some Reed-Solomon decoders that take account of area and find the best algorithm of them in this system. Thereafter we reform a structure of finite field multiplier which reducing the amount of logic gate without losing operation speed to optimize the speed of a Reed-Solomon decoder after reducing area. By the two ways, this decoder is designed with VHDL and verified through APEX20K Demo Board by Logic Analyzer. It occupies 2228 logic elements and 5400 memory bits.

碩士
國立成功大學
電機工程學系碩博士班
95
In this thesis, we focus on video quality control in Digital Video Broadcasting Handheld (DVB-H) system. In addition to the performance analysis of physical layer in DVB-H, we propose a local search algorithm to control video quality in a constrained network. The algorithm helps to indicate both the optimal packet scheduling and the optimal error protection capability in an effective way. We adopt the packet importance to decide the optimal drop set. Moreover, the redundancy for error protection is also taken into consideration. If the level of error protection is too high, it has to drop more video packets due to the limited channel capacity. On the contrary, if the level of error protection is little, correspondingly we could transmit more video packets to obtain a better reconstructed video quality at decoder side. The key contribution of this thesis is to achieve the best trade-off between these factors. Simulations using H.264/AVC video were conducted to evaluate the performance of the proposed scheme. The simulation results show that the packet schedule and the level of error protection selected from the local search achieve the optimal reconstructed video uality at decoder side.

碩士
國立臺灣海洋大學
電機工程學系
92
In the field of digital video broadcasting, it pursuing better quality video programs of the receiver is not the only goal. There is also increasing need in functions (such as PIP and POP). Satellite digital video broadcasts use transponders on a satellite to provide video programs. They can provide a wide broadcasting range. In addition, the direct to home service is currently under active development. Satellites will become the most popular video broadcasting transmission media. In this thesis, we investigate the satellite digital video broadcasting system. For the purpose of receiving multiple channel programs, traditional satellite receivers have to increase the number of tuners. This increases the complexity and the cost of the circuit. In this paper, we propose a multi-channel digital quadrature demodulation method to solve this problem. The so-called digital quadrature demodulation technique chooses the sample rate for signals via certain rules. The correctly demodulated multiple channel outputs can then be obtained from the sampled signal using simple operations. The whole digital quadrature demodulation process is done in the digital domain. This means that it can be easily realized by software. In addition, if the bandpass sampling is used, we can substantially reduce the sampling frequency. In this paper, we apply the multi-channel quadrature demodulation technique to the satellite digital video broadcasting system and perform simulation to verify the goodness of our design. The simulated result shows that the proposed structure is able to successfully demodulate multiple signals. We expect the proposed receiver structure to be implemented in the near future. Keywords: Quadrature Sampling, Bandpass Sampling, Digital Quadrature Demodulation, Digital Video Broadcast.

碩士
國立中央大學
電機工程研究所碩士在職專班
99
Abstract The main topic of this thesis is to design an antenna for compact wireless broadband digital video broadcasting system (Digital Video Broadcasting - Terrestrial, DVB-T). The antenna is fed by probe. A coupling structure in the center of the antenna is designed to generate low band and a chip resistor is added at the end of the antenna to increase bandwidth. The proposed antenna was fabricated on and FR4 substrate. The design parameters, such as the dimension of antenna (width and length) and chip resistor, were extensively analyzed by adjusting at different frequency bands (low-band, middle-band and high band). The return loss and radiation pattern were simulated and measured to verify the design concept. The compact wireless broadband digital video broadcasting system mentioned in the thesis conform with international norms of digital television bandwidth of 470 MHz to 860 MHz; the antenna gain can meet the requirement in real applications. The radiation pattern in E-plane exhibits an eight figure just as conventional monopole antenna. The radiation in H-plane shows an omni-directional pattern.

碩士
大同工學院
資訊工程學系
84
The thesis is dedicated to the study of an algorithm for MPEG-2 transport stream multiplexing in digital video broadcasting systems, which isa branch of network traffic improvement. The MPEG-2 transport stream characterizations for digital video broadcasting systems are presented. In the algorithm part I, we show that the channels can be loadedbalance. And in the part II, we show that we can use the delay buffer toprevent the channel overloading from dividing the transport stream peaks. Furthermore, a new delay stream evaluation criterion is proposed. Thehigh volume, low sensitive is popular to be delayed. Experimental results show that the new algorithm for transport stream multiplexing are potential for use.

碩士
雲林科技大學
電機工程系碩士班
98
The major goal of this thesis is to reduce the number of iterations required by the algorithm in DVB-T2 decoding systems. The overall system is composed of several parts: the outer BCH (Bose, Chaudhuri, and Hocquenghem) code, which can be used for overcoming bursty errors; the inner LDPC (low-density parity-check) code, whose purpose is to increase coding gains; the bit interleaver, which scrambles data bits so that the original message will not suffer too much on bursty channels. After message signals are transmitted through Rayleigh channels, received bits are deinterleaved by using a column twist deinterleaver followed by a parity deinterleaver. Min-Sum Algorithm is used in the inner decoder, which can effectively reduce number of iterations and error rates. Berlekamp-Massey algorithm is then applied in the outer decoder to construct the error location equation. Finally, Chien Search algorithm is used to efficiently locate the locations of errors. Simulation results show that, under all of the specifications for the numbers of column Nc being 8, 12, and 16, and for various code rates (i.e, 1/2, 3/5, 2/3, 3/4, 4/5 and 5/6), the error performance and coding gains can be effectively improved even when the iteration numbers are reduced.

碩士
國立交通大學
電信工程系所
93
This thesis proposes a new encoding and decoding method which can be applied to Digital Video Broadcasting (DVB) Systems. There are many kinds of error correction codes. Low Density Parity Check (LDPC) Code gets a lot of attention recently because its coding gain is near the Shannon limit. Moreover, the decoder is easy to implement and the hardware cost is low. Conventional Digital Video Broadcasting System uses two concatenated codes, an outer code (Reed-Solomon code) and an inner code (Convolutional code), respectively. These two codes have different interleavers. In order to simplify the coding scheme of Digital Video Broadcasting Systems, here we use a single Low Density Parity Check code to substitute for the original Reed-Solomon code and the Convolutional code, together with their interleavers. We use computer simulation to compare the bit error rate performance of the Low Density Parity Check Code and the original concatenated codes in Digital Video Broadcasting Systems.

碩士
國立中山大學
電機工程學系研究所
93
The topic of this thesis presents a digital front end (DFE) of the digital video broadcasting over terrestrial (DVB-T). The DVB-T system is similar to most of the prior digital communication system. It is roughly divided into two major parts, one for channel coding/decoding, and the other for modulation/demodulation. The thesis is mainly focused on the DVB-T digital video broadcasting demodulation part of the receiver and the integration of a complete digital front demodulation system. The major operational processor of the DFE is a 2K/8K dual-mode FFT processor, which has been implemented by the TSMC ( Taiwan Semiconductor Manu-facturing Company ) 0.35um 2P4M CMOS process technology to justify the simulation results as well as the correctness of the proposed architecture.

Currently, the best quality video that can be viewed on our TV is at a resolution of 1920 x 1080 pixels, standardized as High-definition (HD). To view a video even bigger and better than HD, a new resolution has recently been standardized as Ultra-High- Definition (UHD) at a resolution of 3840 x 2160 pixels. However, to broadcast a UHD video using the standard broadcast method, Digital Video Broadcasting (DVB), an exclusive DVB-UHD broadcast profile is being developed, which defines parameters for the content being transmitted, the transmitter-receiver equipment, and the television displays. At present, we only have a broadcast profile for Standard-Definition (SD) and HD. Thus, the objective of this research work is to contribute towards the standardization of the DVB-UHD broadcast profile.

碩士
真理大學
數理科學研究所
96
Watching TV by mobile devices can be realistic. The DVB-H (Digital Video Broadcasting-Handheld) is one of the main standards of mobile digital TV systems. The DVB-H involves the techniques of digital TV and mobile communications such that subscribers can access multimedia information by mobile devices. This theme presents a broadcasting protocol over DVB-H for near video-on-demand services. Based on the greedy approach, the proposed method can efficiently schedule the segments of a video for transmission. As a result, the proposed method can use the bandwidth efficiently and reduce the average waiting times.

碩士
國立交通大學
電信工程系所
94
In this thesis, first we introduce a new structure of dual bandpass filter applying for IEEE 802.11a/b/g. By a serial configuration of a inductive coupled-line (ICL) filter and a capacitive coupled-line filter (CCL) filter, a dual bandpass filter can be designed with a transmission zero between the two passbands. By the two-poles Z matrix analysis, we find that the transmission coefficient of the dual bandpass filter has approximately the same behavior as the individual single-band filter around the corresponding pass-band. The measurements results also agree quite well with the simulation ones. In the next part, a front-end module applied for digital video broadcasting-handheld (DVB-H) is proposed. The module which passband is 470~702MHz includes a bandpass filter, a low noise amplifier (LNA), and a lowpass filter. We integrate the active/passive components by LTCC technology and the measurements almost conform to the specifications.

碩士
國立中央大學
通訊工程研究所
93
ABSTRACT Viterbi algorithm is the well-known and efficiently maximum likelihood decoding algorithm applied to decode convolutional code. In this discussion, it concentrates on the standard of punctured convolutional encoder in DVB-T system. To design and implement a Viterbi decoder agreed with the decoding throughput which limited by the system, on the other hand, to research the soft-decision method for decoding process with the result in promoting the bit error rate！ The way used to soft-decision is by the minimum distance algorithm . Bit branch metrics have different value if the quantized level is not the same for soft-decision decoding. The analysis is focusing on the performance of soft-decision quantized level Q=8 and Q=16 and hard-dec ision and a basis for the coming IC design of Viterbi decoder. In the implementation issue, full parallel architecture and modulo normalization are used to save the source and decoding throughput, then the 3-pinter even block method is used to trace back and decoding the data. At the last, we implement the Viterbi decoder by above-mentioned ways and the soft-decision quantized level is Q=16.

碩士
國立中央大學
通訊工程研究所
93
Many digital signaling applications in broadcasting use Forward Error Correction, a technique in which redundant information is added to the signal to allow the receiver to detect and correct errors that may have occurred in transmission. Many different types of code have been devised for this purpose, but Reed-Solomon codes have proved to be a good compromise between efficiency and complexity. Reed-Solomon error correction has several applications in broadcasting, in particular forming part of the specification for the ETSI digital terrestrial television standard, known as DVB-T. In this thesis, we applied the specification for the ETSI digital terrestrial television standard(DVB-T) to realize the hardware implementation of Reed-Solomon decoder. Using Verilog Hardware Description Language and simulating by software “Modelsim” to confirm our program of RS(204,188,8) are fine and can correct errors which result from bad channel. Then, synthesizing logic-RTL by Synplify.

The present research study investigated the perceived credibility of television news in relationship to the acquisition of knowledge of digital video compositing techniques. An experiment was carried out to verify if acquiring knowledge of digital video post-production techniques affected the perceived credibility of television news. Instrumentation for the experiment included a video stimulus produced with a readily available digital video compositing software package as well as an online post-test questionnaire. A scale for perceived credibility of television news was constructed based on a frequently used operationalization of the concept of credibility. Findings showed that after subjects acquired knowledge of digital video post production techniques, their perception of television news credibility was less than subjects who did not acquire knowledge of digital video post production techniques. Also, the amount of education a subject possessed played a significant role in how he or she perceived the credibility of television news. Frequency of television news consumption, familiarity with digital imaging software tools, and academic background were also examined in relationship to perceived credibility of television news. Implications are explained for improving media literacy education, protecting television news credibility, and designing media effects experiments.

碩士
國立成功大學
資訊工程學系碩博士班
94
During the past years, the Digital Television Broadcast (DVB) standard has been developed rapidly and has also become one of the most popular Digital Television standards. The essential idea of DVB is to replace analog services with digital ones, while DVB2.0 contains a roadmap for the development of digital broadcasting technology. The purpose of DVB 2.0 is to build bridges to the world of computing and telecommunications. With the evolvements of multimedia and Internet techniques, DVB starts to develop interactive TV, of which the data comes from the data broadcasting of DVB. In order to handle the data of DVB data broadcasting, Digital Storage Media Control and Command (DSM-CC) specifications are then defined in DVB. In this thesis, we investigate the data decoding process within data broadcasting by designing and implementing the DSM-CC mechanism. Some issues that are ambiguously defined in the specification of DSM-CC, i.e., memory management, the relation of sections, module composition, content update, management of Service Domain and the problem of path, are clarified. In this thesis, the solutions for resolving the aforementioned issues are also proposed as the references of improving DVB specifications.

The rapid growth of wireless systems has shown little sign of ceasing, due to increased consumer demand for reliable interactive services. A key component of the development has centered on satellite networks, which allows provision of services in scenarios where terrestrial systems are not viable. The Digital Video Broadcasting-Satellite Second Generation (DVB-S2) standard was developed for use in satellite broadcast applications, the foremost being video broadcasting. Inherent to DVB-S2 is a powerful forward error correction (FEC) module, present in both the Physical and Data Link Layer. Improving the error correcting capability of the FEC is a natural advent in improving the quality of service of the protocol. This is more crucial in real time satellite video broadcast where retransmission of data is not viable, due to high latency. The Physical Layer error correcting capability is implemented in the form of a concatenated BCH-LDPC code. The DVB-S2 standard does not define the decoding structure for the receiver system however many powerful decoding systems have been presented in the literature; the Belief Propagation-Chase concatenated decoder being chief amongst them. The decoder utilizes the concept of soft information transfer between the Chase and Belief Propagation (BP) decoders to provide improved error correcting capability above that of the component decoders. The following dissertation is motivated by the physical layer (PL) FEC scheme, focused on the concatenated Chase-BP decoder. The aim is to generate results based on the BP-Chase decoder in a satellite channel as well as improve the error correcting capability. The BP-Chase decoder has shown to be very powerful however the current literature provides performance results only in AWGN channels. The AWGN channel however is not an accurate representation of a land-mobile satellite (LMS) channel; it does not consider the effect of shadowing, which is prevalent in satellite systems. The development of Markov chain models have allowed for better description of the characteristics of the LMS channel. The outcome being the selection of a Ku band LMS channel model. The selected LMS channel model is composed of 3 states, each generating a different degree of shadowing. The PL system has been simulated using the LMS channel and BP-Chase receiver to provide a more accurate representation of performance of a DVB-S2 network. The effect of shadowing has shown to reduce coding performance by approximately 4dB, measured over several code lengths and decoders, when compared with AWGN performance results. The second body of work aims to improve the error correcting capability of the BP-Chase decoder, concentrating on improving the LDPC decoding module performance. The LDPC system is the basis for the powerful error correcting ability of the concatenated scheme. In attempting to improve the LDPC decoder a reciprocal improvement is expected in the overall decoding performance of the concatenated decoder. There have been several schemes presented which improve BP performance. The BP-Ordered statistics decoder (OSD) was selected through a process of literary review; a novel decoding structure is presented incorporating the BP-OSD decoder into the BP-Chase structure. The result of which is the BP-OSD-Chase decoder. The decoder contains two stages of concatenation; the first stage implements the BPOSD algorithm which decodes the LDPC code and the second stage decodes the BCH code using the Chase algorithm. Simulation results of the novel decoder implementation in the DVBS2 PL show a coding gain of 0.45dB and 0.15dB versus the BP and BP-Chase decoders respectively, across both the AWGN and LMS channel.
Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2012.