Digital Video Broadcast

Since the invention of Information Theory by Shannon in 1948, coding theorists have been trying to come up with coding schemes that will achieve capacity dictated by Shannon’s
Theorem. The most successful two coding schemes among many are the LDPCs and Turbo codes. In this thesis we focus on LDPC codes and in particulary their usage by the second
generation terrestrial digital video broadcasting (DVB-T2), second generation satellite digital video broadcasting (DVB-S2) and IEEE 802.16e mobile WiMAX. Low Density Parity
Check (LDPC) block codes were invented by Gallager in 1962 and they can achieve near Shannon limit performances on a wide variety of fading channels. LDPC codes are included
in the DVB-T2 and DVB-S2 standards because of their excellent error-correcting capabilities. LDPC coding has also been adopted as an optional error correcting scheme in IEEE 802.16e
mobile WiMAX. This thesis focuses on the bit error rate (BER) and PSNR performance analysis of DVB-T2, DVB-S2 and IEEE 802.16e transmission using LDPC coding under additive white Gaussian noise (AWGN) and Rayleigh Fading channel scenarios. The power delay profile for all transmissions
was adopted from the ITU channel model. For modelling the fading environment Jakes fading channel model[7] together with ITU Vehicular-A and ITU Pedestrian-B[13] power delay profile parameters were used considering also the Doppler effect. The three scenarios presented in this thesis are the following: (i) simulation of LDPC coding for DVB-S2 standard, (ii) optional LDPC coding as suggested by the WiMAX standard and (iii) simulation of DVB-T2 using LDPC without outer BCH encoder and with outer BCH encoder. During the simulations the encoding algorithm used was Forward Substitution algorithm. Even though the second generation DVB standards and WiMAX standard has been out since 2009, not much comprative results have been published for BCH and LDPC concatenated
coding schemes making use of either a normal FEC frame or a shortened FEC frame. By carrying out the work presented here we tried to contribute towards this end. Throughout the simulations we have considered two different size images as the source of information to transmit. Performances analysis have been given by making comparisons between BER and PSNR values and psychovisually.

Keywords: Low Density Parity Check Coding; BCH coding; OFDM; WiMAX; Digital
Video Broadcasting; Rayleigh Fading Channel; Shortening; Zero-Padding; Digital Image
Processing; Iterative decoding.
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Interactive broadcasting elaborates on the study and realization of novel television networks, able to provide multiple interactive multimedia and Internet based services, utilizing Digital Video Broadcasting advances. On the other hand, IP Multimedia Subsystem (IMS) is a promising solution, that may be adopted in next generation networks and broadcasting systems, providing advanced capabilities and added value data services. In this context, this paper investigates interactive broadcasting systems and IMS convergence and proposes a novel research approach, which could be adopted in interactive marketing, enabling for a more efficient process of collecting and analyzing feedback data from users/viewers. This process may be vital for optimum marketing and advertising purposes. This potential information data may be used to target customers in more efficient and effective ways, i.e. geographical segmentation, increasing the possibility of impulse sells through t-commerce or allow audience to require more information for a company, brand or product, enhancing the experience a customer have with specific brands.

Despite the incessant progress observed in fined and wireless terrestrial communication networks, satellite systems remain an appealing solution for broadcasting, point-to-point, and multicasting telecommunications, because of undemanding customer equipment and wide coverage capability. In this scenario, digital video broadcasting via satellite (DVB-S) is recognized as one of the main market-attractive telecommunication fields. U p to now, expensive discrete GaAs HEMT or FET devices have been used to build up circuitry for satellite applications at Kuband. This article presents the first 12-GHz monolithic receiver for DVB-S applications, implemented in a low-cost silicon bipolar technology. The receiver is based on a superheterodyne architecture, employing a fully integrated LO. To comply with the severe LO phase noise requirement of -101 dBclHz at a 100 kHz offset from the carrier, an innovative VCO topology was used implementing a three-metal-layer integrated transformer. The performance parameters of the integrated receiver fulfill DVB-S standard specifications.

This paper investigates the design of power and spectrally efficient coded modulations based on amplitude phase shift keying (APSK) with application to broadband satellite communications. Emphasis is put on 64APSK constellations. The APSK modulation has merits for digital transmission over nonlinear satellite channels due to its power and spectral efficiency combined with its inherent robustness against nonlinear distortion. This scheme has been adopted in the DVB-S2 Standard for satellite digital video broadcasting. Assuming an ideal rectangular transmission pulse, for which no nonlinear inter-symbol interference is present and perfect precompensation of the nonlinearity takes place, we optimize the 64APSK constellation design by employing an optimization criterion based on the mutual information. This method generates an optimum constellation for each operating SNR point, that is, for each spectral efficiency. Two separate cases of interest are particularly examined: (i) the equiprobable case, where all constellation points are equiprobable and (ii) the nonequiprobable case, where the constellation points on each ring are assumed to be equiprobable but the a priory symbol probability associated per ring is assumed different for each ring. Following the mutual information-based optimization approach in each case, detailed simulation results are obtained for the optimal 64APSK constellation settings as well as the achievable shaping gain.

The terrestrial digital video broadcasting (DVB-T) network planning is the main interest of this article along with a case study for Greece. The basic principles and the guidelines of the DVB-T planning process are presented in conjunction with their application to the establishment of the Greek DVB-T allotment plan. The procedures described in this article were followed by the authors during the International Telecommunication Union (ITU) DVB-T planning project that concluded with the ITU's Regional Radiocommunication Conference 2006 (RRC-06) and the Geneva (GE-06) frequency plan for terrestrial digital radio broadcasting.

Cyclic delay diversity (CDD) is a simple multiple antenna technology which provides additional diversity in Rayleigh fading channels, and therefore, improves the system performance. We recall the principles of CDD and discuss the properties and impact of this transmit (TX) antenna diversity technology. Different applications motivate variations of the CDD principle. This variants are briefly introduced and discussed. We show the application to several types of wireless systems, in particular terrestrial digital video broadcasting, cellular mobile radio communications systems and a wireless communications system using adaptive bit loading (ABL). Simulation results highlight the benefits of CDD for these kind of systems.

We consider the problem of carrier synchronization in future 2nd-generation satellite digital video broadcasting (DVB-S2) receivers. In this scenario, this task is made harder by the complexity constraints, related to the use of consumer-grade equipment. Making use of the distributed pilot symbols of the DVB-S2 standard, low-complexity techniques for fine frequency estimation and for detection in the presence of a strong phase noise, typical of consumer-grade equipment, will be proposed. The performance of the described algorithms will be analysed in detail through computer simulations.

The demands for accessing services at high data rates while on the move, anyplace and anytime, resulted in numerous research efforts to integrate heterogeneous wireless and mobile networks. The focus was mainly put on the integration of the Universal Mobile Telecommunications System (UMTS) and the wireless local area network (WLAN) IEEE 802.11, which is beneficial in terms of capacity, coverage and cost. With the advent of IEEE 802.16(e) the attention of the research community was shifted to its interworking, on one side, with complementary WLANs, and on the other, with UMTS for extra capacity. In addition, there has been also research on UMTS interworking with different broadcasting systems, including the Digital Video Broadcasting system for handheld devices (DVB-H). All these research activities resulted in various heterogeneous architectures where the interworking was performed at different levels in the network. In this article, we address the integration at the UMTS radio access level, known also as very tight coupling. This integration approach exhibits good vertical handover performance and may allow for seamless session continuity during the handover. However, it is a technology specific solution, where not all the mechanisms applied to the integration of one wireless technology can be straightforwardly reused for embedding another. This integration approach introduces various modifications to UMTS that have to be standardized, which makes it a long-term solution. We present here the general architecture for the integration at the UMTS radio access level and discuss the extension of the architectural framework for various types of access systems with as few as possible additional modifications. The focus of the work is put on the vertical handovers. We discuss various vertical handovers among WCDMA, IEEE 802.11, IEEE 802.16e and DVB-H in the considered heterogeneous architecture. We present new handover types, describe the vertical handover procedures and provide performance evaluation of the vertical handovers in different scenarios and for different combinations of the wireless access technologies.

A new combline filter structure with a continuous tunability for both the center frequency and bandwidth is presented in this paper. The passband-width tunability is achieved by placing variable coupling reducers between the filter resonators. The coupling reducers, operating as bandwidth control subnetworks, are designed as detuned resonators made up of a line segment ending in a variable capacitor. The proposed filter structure is experimentally validated with the design, construction in suspended stripline technology, and characterization of a low-cost filter prototype for terrestrial digital video broadcasting receivers operating in the UHF band (470-862 MHz). Other relevant factors, such as the intermodulation distortion produced by the varactors used to control the bandwidth electronically or the power-handling performance of the constructed filter, are also discussed. The reconfigurable filter module described in this paper is very suitable for the design of flexible multifunction receiver subsystems simultaneously supporting signals with a different bandwidth.

A novel joint video encoding and statistical multiplexing (StatMux) method for broadcasting over digital video broadcasting for handhelds (DVB-H) channels is proposed to improve the quality of encoded video and to decrease the end-to-end delay in a broadcast system. The main parts of end-to-end delay in a DVB-H system result from a time-sliced transmission scheme that is used in DVB-H and from the bit rate variations of service bit streams. The time-sliced transmission scheme is utilized in DVB-H to reduce the power consumption of DVB-H receivers. Variable bit rate (VBR) video bit streams are used in DVB-H to improve the video quality and compression performance. The time-sliced transmission scheme has increased the channel switching delay, i.e., switching to a new audio-visual service, in DVB-H. The used VBR bit streams increase the required buffering delays in the whole system. The different parts of end-to-end delay in a DVB-H system can be affected by the used video encoding and multiplexing methods. Different scenarios for encoding and StatMux of video sources for DVB-H application are studied in this paper. Moreover, a new method for jointly encoding and StatMux of video sources is proposed that not only decreases the end-to-end delay but also improves the average quality of compressed video by dynamically distributing available bandwidth between the video sources according to their relative complexity. Performance of the proposed method is validated by simulation results.

The new terrestrial digital video broadcasting standard DVB-T2 provides a specific symbol -called P1-symbolfor the initial time and frequency synchronization. In this paper the maximum likelihood (ML) time and carrier frequency offset (CFO) synchronization scheme, which exploits the structure of the P1 symbol in both time and frequency domains is derived. Two lower-complexity solutions are then proposed: 1) a ML estimator that only exploits the time structure of the P1 symbol and 2) a pseudo ML (PML) scheme that resorts to a suboptimal CFO estimator while still performing ML time synchronization. The proposed schemes are compared in terms of both synchronization capabilities and implementation complexity. The Cramèr-Rao bounds for the CFO estimators are also evaluated. Simulation results in a typical DVB-T2 scenario show that both ML and PML schemes have a very close performance while significantly outperforming existing schemes.

Digital content providers seek to restrict usage by implementing conditional access. One such scenario is the security aspects of digital video broadcast (DVB-S). There has been a history of attacks on this technology to circumvent any security measures and some techniques have been countered by the deployment of customised/provider specific receivers. However, this leads to less choice and the duplication of equipment at the customer level. Open satellite receivers have been introduced to allow a single user to access several different services from a single piece of receiver equipment. These boxes provide a highly configurable environment with software emulations of conditional access systems that is open to abuse. The internet has allowed communities with in-depth expertise to grow up around open receiver equipment; effectively communicating attack methods as they evolve. A new level of emerging attack is a card sharing by which one legitimate user colludes to provide protected content to a larger group of illegitimate users. In this paper we propose countermeasures to protect DVB-S content against this species of attack by enforcing behavioural contracts and correct usage guidelines within the smart card. 1

This paper discusses new technologies in communication systems and particularly the new systems for transmitting audio and video data, which switch from analog to digital principle. The number of digital channels transmitted through satellites increased every day. The trend in the near future is for replacement all the analogue TV and Radio broadcasting with digital one. To unify the implementation of dynamic interactive systems, middleware kernels will be built-in in such systems, as some of these kernels are Open TV and MHP allowing integration of Java virtual machine, TCP/IP stack, browser and etc.

A multi-mode radio communication terminal is a tunable terminal for passing and/or receiving bands in at least two radio communication systems. In the last few years many research resources have been invested in the study of this new type of terminal. In our study, we intend that a multi-mode terminal is a terminal capable of communicating both with a Bent-Pipe satellite and with an On-Board Processor satellite. In the literature different technologies are presented and they can be used to realize the multi-mode capability of a terminal, but, the most suitable technology is the Software Defined Radio (SDR). The SDR is a set of Hardware and Software technologies that allow one to obtain reconfigurable architectures for network and wireless terminals. The goal of our work is to plan a satellite system based on Digital Video Broadcast with the Return Channel Satellite (DVB-RCS) standard in which the Return Channel Satellite Terminals (RCSTs) are able to adapt to the channel state, configuring the transmission chain via software, respecting a certain Quality of Service (QoS) constraint on the Packet Error Rate (PER).

A 70 Mb/s variable-rate 1024-quadrature amplitude modulated (QAM) cable receiver IC with integrated 10 b analogto-digital converter (ADC) and forward error correction (FEC) decoder is presented. The chip accepts an analog 2 V pp V pp V pp differential QAM signal centered at an intermediate frequency. The integrated 10 b ADC digitizes the IF signal, and all subsequent signal processing, including demodulation, timing/carrier recovery, adaptive equalization, and FEC, is performed digitally. The receiver IC is capable of receiving 4, 16, 32, 64, 128, 256, and 1024-QAM modulation formats. The 0.5-m triple level metal N-well CMOS chip has a complexity of 650 k transistors with a core area of 4.9 2 4.9 mm 2 : Power dissipation is 1.8 W at 7 MBaud and 5 V.

The recently introduced Digital Video Broadcasting Satellite to Handheld standard (DVB-SH) allows for digital broadcasting service provision to small mobile terminals in satellite/terrestrial hybrid networks. In this paper, the key results from an in-depth DVB-SH performance assessment campaign lasting two years are reported. The performance results reported encompass simulation, laboratory and field trials key findings and allow deriving recommendations for preferred system parameters and configurations. [email protected]; [email protected]).

The fourth-generation (4G) of cellular terminals will integrate the services provided by previous generations second-generation/third-generation (2G/3G) with other applications like global positioning system (GPS), digital video broadcasting (DVB) and wireless networks, covering metropolitan (IEEE 802.16), local (IEEE 802.11) and personal (IEEE 802.15) areas. This new generation of hand-held wireless devices, also named always-best-connected systems, will require low-power and low-cost multistandard chips, capable of operating over different co-existing communication protocols, signal conditions, battery status, etc. Moreover, the efficient implementation of these chipsets will demand for reconfigurable radio frequency (RF) and mixed-signal circuits that can adapt to the large number of specifications with minimum power dissipation at the lowest cost. Nanometer CMOS processes are expected to be the base technologies to develop 4G systems, assuring mass production at low cost through increased integration levels and extensive use of digital signal processing. However, the integration in standard CMOS of increasingly complex analog/RF parts imposes a number of challenges and trade-offs that make their design critical. These challenges are addressed in this paper through a comprehensive revision of the state-of-theart on transceiver architectures, building blocks and design trade-offs of reconfigurable and adaptive CMOS RF and mixed-signal circuits for emerging 4G systems.

This paper presents the results of an evaluation of a propagation model based on ray-tracing techniques using a game engine and Graphics Processing Unit (GPU) in outdoor scenarios, as a gap-filler for a Digital Video Broadcasting Handheld (DVB-H) service. This model involves complete identification of the parameters of wave propagation, multipath components between the transmitter and the receiver as attenuation, time delay of arrival (TDA), full polarimetric transmission matrix, direction of arrival DoA and the direction of departure DoD. In the paper, we present the results of the simulation and compare them with measurements, obtaining a satisfactory fit.

Digital video broadcasting terrestrial (DVB-T) is being adopted by many countries all over the world. Recently, DVB-H, a new standard compatible with DVB-T, has been proposed for handheld terminals, which demands low power consumption. In this study, a continuous-time filter for DVB-T/H receivers is presented. High linearity and low noise are achieved by selecting a Gm-C filter topology implemented with a novel programmable transconductor based on MOS transistors in the triode region. The filter is tunable in a wide range, which makes it suitable for VLSI integration. The filter has been designed in a standard 0.5 mm CMOS technology with a single 3.3 V supply voltage. Experimental results show an IM3 of 258 dB for a two tone experiment with 2 Vpp output signal centred at 2 MHz.

This paper shows a model used to calculate the efficiency of migration from analog TV technology to digital TV technology in Indonesia. Analogue television broadcasting in Indonesia uses 470-806 MHz or channel 22-62 and will migrate to digital television terrestrial (DTT) standard in a few years. Two standard had made for the migration, those are DVB-T and DVB-T2. This migration will provide frequency spectrum called digital dividend as DTT allows the television broadcaster to use only about 1/6 spectrum than the analogue [1]. The digital dividend propagation characteristic is very high valuable it has to used optimally in order to generate more benefit to the people, business stakeholders and government. That is why it is very important for us to create a model in order to provide best scenario with best scenario between DVB-T or DVB-T2 which provide greater profit for Indonesia's government.

Othogonal frequency division multiplexing with a suitably chosen guard interval is a n effective means of eliminating intersymbol interference for high-rate transmission over fading dispersive channels. T i m e variations of t h e channel, however, lead t o a loss of subchannel orthogonality, resulting in interchannel interference (ICI). This article examines t h e effects of IC1 through analysis a n d simulation, in t h e context of a system design for digital video broadcasting t o mobile receivers. It is shown t h a t IC1 can b e modeled as a n additive Gaussian random process t h a t leads t o a n error floor which can be determined analytically as a function of the Doppler frequency. Antenna diversity a n d trellis coding are t h e n examined as methods for reducing this error floor.

In this article we present a system for sharing a Conditional Access Module among different visualization devices. Current pay-TV systems require having conditional access modules and smart cards replicated at every visualization device willing to access Pay-TV contents. In this article, we show how a home gateway, capable of securely distribute decryption keys to home visualization device, an inexpensive descrambler, and a home network, enable a flexible solution to access Pay-TV 1 .

H.264 Scalable Video Coding (SVC) is an extension to the Advanced Video Coding (AVC) H.264 standard which provides efficient scalability functionalities on top of the high coding efficiency of H.264/AVC. SVC allows for temporal, spatial, and quality scalability of the output video stream, encoding the video information into an H.264/AVC base layer and a series of enhancement layers which incrementally improve the quality, increase screen resolution and/or frame rate. SVC is particularly suited for mobile TV reception, since the received video quality is adaptable to variable reception conditions and heterogeneous receiver capabilities. However, mobile TV Digital Video Broadcasting (DVB) standards such as DVB-H and DVB-SH were designed prior to the introduction of SVC, and therefore the underlying transmission protocols are not optimized for scalable video delivery. In this overview paper, we review recently proposed solutions for SVC stream adaptation on the underlying DVB-H/SH protocols, and point out novel technical solutions that are currently under consideration for the next generation mobile broadcasting standard DVB-NGH.

In this paper, a quality-of-service (QoS) multicast routing protocol, i.e., the core-based tree based on heuristic genetic algorithms (GAs), has been implemented and applied over a high-altitude platform (HAP)-satellite platform. The proposed multicast routing algorithm is called the constrained costbandwidth-delay GA (CCBD-GA). To achieve a better optimization of the multicast tree cost, a new algorithm called HULK-GA, which is based on the GA and on a proposed broadcast metric, has been developed. Finally, an algorithm called hybrid costbandwidth-delay GA has been proposed, taking into account both CCDB-GA and HULK-GA characteristics to obtain an overall algorithm that can consider QoS routing constraints and minimize the overall cost per link of the considered multicast tree. The joint bandwidth-delay metrics can be very useful in hybrid platforms such as the platform considered, because it is possible to take advantage of the single characteristics of the satellite and HAP segments. The HAP segment offers low propagation delay, permitting QoS constraints based on maximum end-to-end delay to be met. The satellite segment, instead, offers a larger footprint but higher propagation delay. The joint bandwidth-delay metric permits the traffic load to be balanced, respecting both QoS constraints.

DVB-T2 implements a very flexible time interleaving that allows multiple tradeoffs in terms of time diversity, latency and power saving. In this paper, we study in detail these tradeoffs in the context of mobile reception. Together with time diversity, we also investigate the impact of reduced time de-interleaving memory and Alamouti-based MISO in the mobile reception of DVB-T2 services. In addition, we propose the utilization of upper layer FEC protection in order to overcome the limitations of the DVB-T2 physical layer for the provision of long time interleaving, and enable fast zapping. The performance is evaluated by means of simulations in mobile channels that include the presence of fast fading and shadowing in the received signal.

In this letter, the impact of a magneto-dielectric resonator on a DVB-H antenna is investigated. A frequency reconfigurable antenna using a folded monopole antenna structure and varactor diodes is proposed. Two different designs are realized with and without the resonator. A measured instantaneous 6-dB bandwidth wider than 8 MHz is obtained continuously between 470 and 862 MHz for both prototypes. Design methodology is described. Measured return loss, gain, directivity, and radiation pattern are presented for different frequencies.

The Hybrid Fiber Coax (HFC) is a modern broadband access network, providing advanced interactive services such as Internet access, digital interactive television and cable telephony. The edge costs dominate the cost of launching new services, at the time of deployment (CapEx) as well as for maintenance (OpEx). Therefore next-generation edge devices aim at the convergence of these services and their platforms into a single multi-service infrastructure, thus sharing resources and bandwidth. The focus of this paper is on the HFC access network design for bandwidth-intensive TV services, bringing standard as well as switched broadcast technologies into play. Standard broadcast TV service deployments, offered through the Digital Video Broadcast (DVB) platform, require low installation costs, but the bandwidth consumption increases linearly with the number of available TV channels, even for very unpopular channels. Switched broadcast TV channels, offered on the (Euro-) DOCSIS platform together with other interactive unicast services such as Video on Demand, are only streamed to a node on the HFC access network if they are requested locally, thus limiting bandwidth consumption for less popular channels. We present an access network design tool, based on an analytical TV traffic model, minimizing the installation cost on the edge devices and study the influence of the most important traffic and content parameters.

Broadband satellite services to fixed terminals are currently offered in the forward link by the 2nd Generation (2G) Digital Video Broadcasting Satellite (DVB-S2) standard. For this standard the use of powerful Low-Density Parity-Check (LDPC) error correcting codes has been adopted performing within approximately 1 dB from the Shannon capacity limit. This paper studies and compares for the first time in a systematic manner different approximation methods used in check node update computation of DVB-S2 LDPC decoding with the aim of reducing computational complexity. Various performance evaluation results are presented for a wide range of DVB-S2 parameters, such as LDPC codeword size, coding rate, modulation format and including several decoding algorithms. It is shown that the proposed check node update approximations have a robust behavior, i.e. the resulting performance is quite independent of the DVB-S2 modulation and coding parameters. It is further shown that these approximations perform very close to the optimal Sum-Product Algorithm (SPA) in degradation, which is less than 0.2 dB. Despite this small degradation, the reduction in computational complexity compared to the optimal SPA is significant and can be as high as 40% in computational time savings.

(T-DMB) are two popular broadcasting standards that enable digital television transmissions to handheld receivers. This paper presents a comprehensive performance comparison between the physical layers of DVB-T/H and T-DMB when employed for mobile communications. By exploiting a recently proposed fast simulation model, we assess the BER of the two coded OFDM systems in several realistic scenarios, taking into account Rayleigh and Rice channels, different mobile speeds, inner and outer channel coding, channel estimation, and one or two receive antennas. Our comparison shows that the DVB-T/H physical layer performance highly depends on the delay spread of the channel, whereas T-DMB is less sensitive to the frequency selectivity of the channel. As a result, DVB-T/H yields better performance than T-DMB in typical Rayleigh channels with significant delay spread. On the contrary, at high SNR, T-DMB outperforms DVB-T/H in Rice channels with low delay spread. As a side result, we show the performance improvement of DVB-H produced by MPE-FEC at the data link layer.

Digital Video Broadcasting via satellite is being widely deployed worldwide. The first generation European standard (DVB-S) is a QPSK based system that supports up to 40 Msymb/s transmission rates. The second generation DVB-S2 specification recently finalized incorporates higher order modulations from 8PSK to 32 APSK . Physical layer impairments on the transmitreceive link include those introduced by the channel, such as reflections and interference, as well as those induced by various components in the system, such as tuner I/Q imbalance or amplifier non-linearity. These impairments degrade the received SNR and may in some cases affect the convergence behavior of various loops in the receiver. The paper provides a qualitative and quantitative description of the system and channel impairments and their effects on the received cluster SNR.

Signal Space Diversity (SSD) has been lately adopted into the second generation of the terrestrial digital video broadcasting standard DVB-T2. In this paper, a bitinterleaved coded modulation receiver for the DVB-T2 standard is detailed. An LDPC decoder based on a vertical layered schedule is the main novelty of this work. It enables an efficient exchange of extrinsic information between the rotated demapper and the LDPC decoder if an iterative receiver is considered. The design and the FPGA prototyping of the resultant architecture are then described. Low architecture complexity and good performance represent the main features of the proposed receiver.

Bu çalışmada dünyanın en büyük video platformu Youtube ‘un üniversite son sınıf öğrencilerinde kullanımı ile ilgili bir araştırma yapılmıştır. Sosyal medyanın ortaya çıkması ile beraber artış gösteren multimedya kullanımı yeni medyaya yeni bir boyut kazandırmış ve medya tüketiminin geleneksel medyadan yeni medyaya doğru yönelmesine neden olmuştur. Geçmişte sadece televizyon aracılığı ile izlenen video görüntüler bugün bir tık kadar yakınımıza gelmiştir. Bu bir “tık” kadar yakınlaşan içeriğin özellikle Youtube platformu sayesinde geleneksel medyadan sosyal medyaya doğru kaymasına neden olmuştur. Bu çalışmada üniversite son sınıf öğrencilerinin Youtube platformunu nasıl algıladıkları ve nasıl kullandıkları araştırılmıştır. Araştıranın birinci bölümünde sosyal medya kavramı hakkında kavramsal derinlemesine bir inceleme yapılmış ardından Youtube hakkında tarihsel ve platformun özelliklerini kapsayan bilgiler araştırılmıştır. Youtube hakkında yapılan önceki araştırmalar ışığında platformun kullanım alanlarının incelendiği araştırmanın ikinci bölümünde 800 üniversite son sınıf öğrencisine Youtube kullanımları ile ilgili hazırlanan bir anket hazırlanmıştır. Araştırmanın analiz bölümünde üniversite son sınıf öğrencilerinin Youtube kullanımı ile ilgili yedi faktör incelenmiştir. Platformun eğlendirme aracı olarak kullanımı, müzik dinleme aracı olarak kullanımı, eğitsel amaçlar, TV’ye alternatifliği, yalnızlık giderme, haber verme aracı ve boş zaman giderme aracı olarak faktör yükleri incelenmiştir. Araştırmanın sonucunda Youtube için hazırlanan ölçeğe özellikle Youtube’da kendi kanalları olanların, platforma daha sık girenlerin, platforma akıllı telefon yolu ile giriş yapanların daha olumlu görüş bildirdikleri gözlemlenmiştir.

Impulsive noise is known to be one of the most damaging types of wideband interference present in wireless communications systems, such as Universal Mobile Telecommunications Systems, Bluetooth, and Digital Video Broadcasting-Terrestrial. In order to quantify how impulsive noise degrades the quality of service (QoS) of a particular system and to evaluate the electromagnetic compatibility (EMC) requirements of a practical receiver under realistic impulsive noise conditions, it is necessary to use a flexible and modular impulsive noise generator. The primary objective of this paper is to present a low-complexity and highly flexible impulsive noise generator whose software module is implemented in a digital signal processor. In contrast to existing commercial equipment, the software implementation preserves the statistical characteristics of the measured impulsive noise parameters. In the proposed implementation, the generator presents two levels of flexibility that make it especially suitable for performing QoS tests and EMC conformance testing in realistic impulsive noise scenarios. First, the application is independent of the noise source under study. Second, the modularity of the testbed makes the generation of impulsive interference in different frequency bands possible. Experimental results confirm the feasibility and achievable performance of the proposed testbed.

In this paper, we present a complete framework of an end-to-end error resilient transmission of 3D video over Digital Video Broadcasting -Handheld (DVB-H) and provide an extensive analysis of coding and transmission parameters. We perform the analysis for different coding and error resilience schemes using different contents coded at different bitrate levels. Throughout the experiments, we investigate the effects of video content type, video bitrate, coding method and unequal protection level for different channel conditions. The results show that Multi-view Coding (MVC) coding outperforms Simulcast and distribution of available bitrate between video quality and Forward Error Correction (FEC) protection is an important factor in different channel conditions.

We recall the principles of cyclic delay diversity (CDD) and discuss the properties and impact of this transmit antenna diversity technology. Different applications motivate variations of the CDD principle. This variants are briefly introduced and discussed. We show the application to several types of wireless systems, in particular terrestrial digital video broadcasting, cellular mobile radio communications systems and a wireless communications system using adaptive bit loading. Simulation results show the benefits of CDD for these kind of systems.

The DVB-H (Digital Video Broadcasting for Handheld devices) specification was standardized by ETSI in 2004 to achieve IP data broadcasting ("datacasting") to handheld terminals. DVB-H emerged as an evolution of DVB-T, introducing new features -mainly at the data link layer-allowing for power saving at the receiver and for better tolerance to a mobile fading channel. This paper presents a laboratory-based software implementation of the DVB-H data link layer, combined with the appropriate physical-layer hardware components to form a complete DVB-H chain. Measurements are carried out to evaluate the efficiency of the new features of DVB-H.

A novel approach is here presented to embed a low-priority data stream into a high-priority data stream for OFDM wireless communications. The main improvement with respect to conventional hierarchical modulations is that the lowpriority data stream can be decoded from the received subcarrier symbols without any previous equalization in case of multipath fading channel. As a consequence, the expected performance is independent of the channel estimation method used to equalize the channel. The low-priority signal is superimposed on the highpriority symbols using a dirty paper coding technique. As a result of the analysis of the proposed method, several improvements to reduce the interference on the high-priority symbols are introduced. The performance of our scheme has been compared with that of a conventional hierarchical modulation using DVB-T system parameters, showing a considerable improvement for multipath fading channels.

We present two new iterative decoding algorithms for channels affected by strong phase noise and compare them with the best existing algorithms proposed in the literature. The proposed algorithms are obtained as an application of the sum-product algorithm to the factor graph representing the joint a posteriori probability mass function of the information bits given the channel output. In order to overcome the problems due to the presence in the factor graph of continuous random variables, we apply the method of canonical distributions. Several choices of canonical distributions have been considered in the literature. Well-known approaches consist of discretizing continuous variables or treating them as jointly Gaussian, thus obtaining a Kalman estimator. Our first new approach, based on the Fourier series expansion of the phase probability density function, yields better complexity/performance tradeoff with respect to the usual discretized-phase method. Our second new approach, based on the Tikhonov canonical distribution, yields near-optimal performance at very low complexity and is shown to be much more robust than the Kalman method to the placement of pilot symbols in the coded frame. We present numerical results for binary LDPC codes and LDPC-coded modulation, with particular reference to some phase-noise models and coded-modulation formats standardized in the next-generation satellite Digital Video Broadcasting (DVB-S2). These results show that our algorithms achieve nearcoherent performance at very low complexity without requiring any change to the existing DVB-S2 standard.

Raptor codes have been standardized as application layer forward error correction (FEC) codes for Multimedia Broadcast and Multicast Services (MBMS) and Digital Video Broadcast (DVB) due to their extraordinary advanced FEC protection and performance. Raptor codes are known to have characteristics very close to ideal and provide a wide range of operating flexibility and efficiency unmatched by other codes, and in particular they are an excellent implementation of fountain codes. Until now, investigations of the application of Raptor codes to UMTS and EPGRS have used an overall system model that does not accurately model the physical channel and user mobility, simplistically assuming independent random packet losses at the application layer. We investigate MBMS in UMTS in a much more realistic and complete simulation environment by considering advanced and complete channel models that simulate the physical channel and user mobility in a cellular network. We use this realisitic simulation environment to determine optimal system parameters under different mobility models, with different bearer parameters, and without and with selective combining. More specifically, we investigate joint settings of the Raptor code rate, the Turbo code rate, transmission power, etc., to find settings which provide reliable download delivery of files using minimal transmission energy. One of our main results is that optimal system-wide operating points use low transmission power and a modest amount of Turbo coding that results in relatively large radio packet loss rates that is compensated for by using a substantial amount of Raptor coding. These optimal operating points use far less transmission energy for download delivery of files than possible operating points without Raptor.