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The flexibility of future mobile networks exploiting modern technologies such as cloud-optimized radio access and software-defined networks opens a gateway to deploying dynamic strategies for live and on-demand content delivery. Traditional live broadcasting systems are spectral inefficient. It takes up a lot more radio spectrum than that of mobile networks, to cover the same size of an area. Furthermore, content caching at base stations reduces network traffic in core networks. However, numerous duplicated copies of contents are still transmitted in the unicast fashion in radio access networks. It consumes valuable radio spectrum and unnecessary energy. Finally, due to the present of numerous mobile receivers with a wide diversity of wireless channels in a base station coverage area, it is a challenge to select a proper modulation scheme for video broadcasting to optimize the quality of services for users. In this thesis, the challenges and the problems in the current strategies for content delivery are addressed. A holistic novel solution is proposed that considers user preferences, user mobility, device-to-device communication, physical-layer resource allocation, and video quality prediction. First, a system-level scheduling framework is introduced to increase the spectral efficiency on broadcasting live contents onto mobile networks. It considers the audience preferences for allocating radio resources spatially and temporally. Second, to reduce the redundant transmissions in radio access networks, a content distribution system that exploits user mobility is proposed that utilizes the urban-scale user mobility and broadcasting nature of wireless communication for delay-tolerant large size content. Third, to further reduce the energy consumption in network infrastructure, a content distribution system that relies on both user mobility, and device-to-device communication is proposed. It leverages the mobile users as content carriers to offload the heavy mobile traffic from network-level onto device-level. Fourth, to mitigate the multi-user channel diversity problem, a cross-layer approach is deployed to increase the video quality for users especially for those who have a low signal-to-noise ratio signal. Finally, data mining techniques are employed to predict video qualities of wireless transmissions over mobile networks. The holistic solution has been empirically developed and evaluated. It achieves high spectral and energy efficiency and mitigates the video quality degradation in mobile networks.

No / This work presents a novel broadband monopole antenna for digital video broadcastingterrestrial (DVB-T) application. The proposed antenna consists of a grating patch and a concave rectangular ground plane with defected ground plane, and the Multiple Split-Ring Resonator (MSRR). The added part in the ground plane and the meta-material are used to enable the antenna height reduction for fixed ranges of operating frequency. The antenna can operate from 468 MHz to 894 MHz frequency range corresponding to 62.5% of impedance bandwidth for |S11|<-7.5 dB. Details of the proposed antenna designs and experimental results of the constructed prototypes are presented and discussed.

This thesis consists of two parts. Part one includes the design procedure and implementation of the building blocks for an RF tuner module used in the Digital Video Broadcasting ¡V Terrestrial ¡]DVB-T¡^system. It contains the comparison of several RF tuner architectures, frequency planning, and link-budget analysis. Measurement results for the designed tuner operating in the frequency range from 50 to 860 MHz show that the maximum power gain ranges from 49 to 57.6 dB. The entire range for gain control is over 60 dB. In the maximum gain state, the noise figure ranges form 6.8 to 11.5 dB, the output third-order interception point¡]OIP3¡^ranges from 11.7 to 13.8 dBm, and the image rejection is over 50 dB. By applying the simplified single-carrier modulation signals, the tuner can pass the DVB-T system specifications with respect to the adjacent-channel and overlapping-channel protection ratios. In part two, an RFIC design for low-noise variable-gain amplifier that can be used in the RF front end of DVB-T system is presented. It operates from 100 to 900 MHz and dissipates 59.4 mW under a 3.3-V power supply. In the maximum gain state, measurement results for this RFIC show that the noise figure is less than 4 dB, the maximum gain is more than 14 dB, and the OIP3 is about 6.8dBm. The entire gain control range is over 40 dB.

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.

This thesis includes two topics. The first one is a low-power double-edge triggered flip-flop.The other is a orthogonal frequency division multiplex (OFDM) demodulator compliant with the Digital Video Broadcasting Handheld (DVB-H). Low-power double-edge triggered flip-flop (DETFF) is based on multi-Vth transistors technique. Since low threshold voltage transistors are able to generate large leakage current, they are suitable to drive big loads. By contrast, high threshold voltage transistors are more appropriate to latch data due to their low leakage. Therefore, a single latch double-edge triggered flip-flop utilizing multi-Vth transistors can be a low power and high speed design without paying the price of large area. The proposed OFDM demodulator is compliant with the DVB-H standard. The received DVB-H signal is processed by an RF front-end and the following analog-to-digital converter. Then, the digital signal is fed into the demodulator to adjust and calibrate the frequency, timing offset and channel estimation. The proposed DVB-H demodulator is mainly composed of five blocks : symbol timing synchronization block, carrier frequency offset compensation block, fast Fourier transform block, scatter pilot detection block and channel compensation block.

Η παρούσα διπλωματική εργασία εκπονήθηκε στο Εργαστήριο Ασύρματης Τηλεπικοινωνίας του τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Υπολογιστών. Ο στόχος της εργασίας αυτής ήταν η μελέτη της μετάδοσης κωδικοποιημένου βίντεο H.264/AVC στο δίκτυο WiMAX με βάση τη χρήση τριών σχημάτων διαμόρφωσης φυσικού επιπέδου του σήματος βίντεο. Λαμβάνοντας υπόψιν την τεράστια εξέλιξη των ασύρματων δικτύων, αλλά και των συσκευών που μπορούν να υποστηρίξουν πολυμεσικές εφαρμογές, καθιστούν τελικά τη μετάδοση βίντεο μια από τις σημαντικότερες προκλήσεις και ένα δημοφιλή ερευνητικό προσανατολισμό. Σημαντικό ρόλο στη μετάδοση του βίντεο διαδραματίζουν οι παράμετροι που διασφαλίζουν την Ποιότητα των Παρεχόμενων Υπηρεσιών, όπως το εύρος ζώνης, η καθυστέρηση, η διακύμανση της καθυστέρησης και φυσικά η απώλεια πακέτων. Ωστόσο, σε ένα δίκτυο υπάρχουν ποικίλλες παράμετροι που πρέπει να λαμβάνονται υπόψιν κατά τη μετάδοση πολυμεσικής πληροφορίας και στην παρούσα εργασία έγινε μια προσπάθεια να εξεταστεί το θέμα υπό το πρίσμα της διαμόρφωσης φυσικού επιπέδου. Το εργαλείο που χρησιμοποιήθηκε για τη μελέτη αυτή, είναι ο εξομοιωτής δικτύων NS-2, η έκδοση ns-2.29. Για την εξαγωγή των γραφικών παραστάσεων χρησιμοποιήθηκε το Matlab R2009b, ενώ για την εξαγωγή των σχημάτων το Microsoft Office Visio 2010. / This diploma thesis was developed at the Laboratory of Wireless Communications, at the Department of Electrical and Computer Engineering. The objective of this work was to study the transmission of the encoded video H.264/AVC through its transmission over WiMAX network based on the use of three physical layer modulation schemes of the video signal. Considering the tremendous evolution of wireless networks and the fact that modern devices can support multimedia applications, it cannot be denied that video broadcasting is of major importance and constitutes a great challenge for the engineers for further research. Parameters that ensure quality of service, such as bandwidth, delay, delay variation and of course packet loss, play dominant role in the optimization of video transmission. However, in a network, there are various parameters that should be taken into consideration when transmitting multimedia data. The tool used for this study is the network simulator NS-2, the version ns-2.29. In order to export the graphics the software that was used is Matlab R2009b, while the Microsoft Office Visio 2010 software was used to export the figures.

H παρούσα πτυχιακή εργασία επικεντρώνεται αρχικά, στη μελέτη των προτύπων της επίγειας και φορητής ψηφιακής τηλεοράσης (DVB-T και DVB-H). Το DVB-T αποτελεί τo πρότυπο της επίγειας µετάδοσης που έχει αναπτυχθεί µε ιδιαίτερα πολύπλοκο τρόπο από ότι τα προηγούµενα πρότυπα για δορυφορική και καλωδιακή µετάδοση. Με το DVB-T επιτυγχάνονται καλύτερες επιδόσεις απ’ ότι µε την αναλογική μετάδοση και προσφέρει πολλά πλεονεκτήµατα στην επίγεια µετάδοση αλλά και λήψη του σήµατος. Επειδή αποδείχθηκε σχετικά νωρίς ότι το DVB-T έχει μειονεκτήματα σε ότι αφορά το broadcasting τηλεοπτικού σήματος σε κινητά τηλέφωνα, γεννήθηκε η ιδέα για ένα σύστημα αποκλειστικά για φορητές συσκευές βασισμένο στο DVB-T. Καλείται DVB-H (DVB-Handheld). Δεδομένου ότι τα συστήματα ψηφιακής μετάδοσης DVB-T και DVB-H χρησιμοποιούν για τη διάδοσή τους το επίγειο και δορυφορικό κανάλι, γίνεται εκτενής ανάλυση των παραμέτρων που επηρεάζουν την επίγεια και δορυφορική μετάδοση, κυρίως από την οπτική των απωλειών. Στη συνέχεια, γίνεται ανάλυση όλων των σταδίων που λαμβάνουν χώρα κατά την εκπομπή και λήψη ενός OFDM σήματος μέσω ενός φυσικού καναλιού, διαμόρφωση η οποία χρησιμοποιείται κατά κόρον στα πρότυπα DVB-T και DVB-H. Έπειτα, προσομοιώνουμε μέσω του MATLAB όλη τη διαδικασία της OFDM μετάδοσης και λήψης, εξάγοντας τις γραφικές παραστάσεις με τη μορφή του OFDM σήματος σε κάθε στάδιο. Τέλος, θα μελετήσουμε την επίδραση του ασύρματου καναλιού (δορυφορικού και επίγειου) στην εξασθένηση του OFDM σήματος, στο σταθμό λήψης και θα εξάγουμε τις γραφικές παραστάσεις, επιβεβαιώνοντας την εξασθένηση αυτή. / This project focuses initially on the study of patterns of terrestrial and mobile digital television (DVB-T and DVB-H). The DVB-T standard is the terrestrial broadcasting standard that has been developed in a very complex way than previous standards for satellite and cable broadcasting. By implementing DVB-T we can achieve much better performance than analog transmission as it offers many advantages for terrestrial transmission and reception. Since it has been proved early on that the DVB-T has disadvantages in terms of the broadcasting of television signals to mobile phones, there has been created an idea for a system that exclusively focuses on mobile devices, based on DVB-T. It is called DVB-H (DVB-Handheld). Since the digital broadcasting systems of DVB-T and DVB-H use the terrestrial and satellite channel to transmit information, an extensive analysis of parameters affecting the terrestrial and satellite transmission takes place, mainly from the perspective of losses. Then, there takes place an analysis of all stages that occur when transmitting and receiving an OFDM signal through a natural channel, modulation which is widely used in DVB-T and DVB-H. Then, we run a MATLAB simulation for the whole process of OFDM transmission and reception, exporting graphs of the form of the OFDM signal at each stage. Finally, we will study the effect of wireless channel (satellite and terrestrial) as far as the weakening of the OFDM signal is concerned at the receiving station and we will export the graphs, confirming the aforementioned attenuation. .

M. Ing. / Digital Video Broadcasting-Handheld (DVB-H) is a technology that enables the reception of television services/programmes on a specific mobile handheld device. MultiChoice Subscriber Management Services (Propriety) Limited, in the year 2006, commenced a project in South Africa; to deploy a trial DVB-H network. The initial phase of the project included the major cities, namely Johannesburg, Cape Town and Durban. The trial network deployed in South Africa assisted MultiChoice in optimizing the efficiency and reliability of the system. It was at this stage that MultiChoice decided to deploy the DVB-H network in other parts of Africa. MultiChoice soon applied for frequency licenses in Nigeria, Kenya and Namibia. These licenses would enable MultiChoice to operate the DVB-H networks on a commercial platform in those countries; and would also enable MultiChoice to start generating an income by providing this service. Shortly after being awarded a license to broadcast DVB-H, a commercial DVB-H network was launched in Kenya in April 2007. The network consisted of two broadcast sites, at the time. MultiChoice came to an agreement with one of the local Mobile Network Operators (MNO) in Kenya to assist MultiChoice in getting the mobile television handset to the Kenyan people. The MNO possessed the required customer base and also the correct billing infrastructure. An immediate concern was raised by the MNO, about the DVB-H network coverage. With DVB-H, portable outdoor network coverage is guaranteed; however, to obtain coverage inside a building, can be somewhat problematic, especially if that building consists of two or more walls. It will be difficult for the DVB-H signal to penetrate those walls. The MNO’s retail outlets were mostly situated in shopping centre type buildings, hence, the MNO put forward a request for coverage inside the outlets where the mobile handset will be sold. This means that network coverage inside these shopping centre type buildings was required. Therefore, an indoor broadcast system was required in order to obtain the required coverage inside the building. MultiChoice decided to undertake a project to design and build this type of system for the current trial DVB-H network deployed in South Africa. This project would be used as a case study for future projects to be implemented for the network in Kenya. In order to successfully implement an Engineering related project, it is essential to consider both the Project Management aspects and the Engineering Management aspects of that particular project. These two concepts are very closely linked and should not be considered individually when implementing an Engineering project. It is understood that all projects go through certain life cycle phases in some form or other. This document provides the background theory to the four commonly recognized phases of the Project Life Cycle, it is then further shown how various aspects of these life cycle phases were applied to the actual project; and how the implementation of these aspects could improve project performance in the future. Some Engineering Management principles are also discussed and shown how they were applied to the actual project. Elements of this case study shall provide useful information for the projects to be implemented in Kenya.