Turkey is considering privatizing its telecommunications system. Any developing country must analyze whether its economic, social, and institutional environment is appropriate for the privatization of a utility. The purposes of this study are (1) to establish a model to assist policy makers, (2) to analyze whether Turkey meets the prerequisites for telecommunications privatization, and (3) to provide Turkish leaders pragmatic policy alternatives pertaining to privatization of the Turkish Telecommunications system.High inflation rate, weakness of the private sector and the lack of regulatory regime are the major impediments facing Turkey's privatization efforts. Turkey might consider several options including (1) not privatizing at all, (2) retaining public ownership of the network operations while privatizing only the physical equipment market, or (3) following the British privatization model.

In a telecommunications network locating user equipment (paging) is a common procedure. Proposed functionality for 4G and 5G allows for eNB initiated paging via X2 interfaces. In this thesis machine learning algorithms were evaluated in order to reduce page signalling. Additionally, two paging schemes based on machine learning were proposed and compared to a common method of paging through cost models. The results show that signalling cost can be reduced by up to 80%.

The purpose of this thesis rose from tackling a specific project led by Cybercom Group. Water Sense was proposed after municipalities expressed the need to conveniently conduct measurements on water in Swedish lakes, and remotely get access to these data. The varying and infrequent nature of measurements result in an inefficient power consumption when a conventional sensor platform is used. Internet of Things is a relatively new and ever-evolving field for wireless sensor networks, where Low Power Wide-Area Network protocols are utilized to cleverly save power. One of these LPWAN protocols is LoRaWAN, a MAC layer protocol that runs on top of the PHY layer protocol LoRa. The chosen platform hardware for sensor nodes is an Adafruit feather equipped with a LoRa radio module, and the Contiki operative system was to be imported and integrated. Contiki OS is developed for small IoT systems with low-power, while offering networking mechanisms and a range of protocols typically utilized in WSNs. The adaptive and modular nature of Contiki allows for custom pairing of protocols to target a specific topology. LoRaWAN has a number of constraints that are disadvantageous for Water Sense, most prominently being a single-hop protocol. Contiki already supports several platforms with drivers, but the CPU and radio module of the Adafruit feather are not one of them. The goal was to integrate the LoRa PHY hardware with Contiki and have an adaptive platform for Water Sense and other scenarios. Unfortunately not all initial goals were achieved, and the physical layer was not fully integrated with Contiki’s APIs. However, the drivers needed for an operational physical layer were completed and range test could be conducted. Therefore, this thesis details the work done for implementing the physical layer and a study on Contiki’s data link protocols in proposed configurations for Water Sense.

During the thesis work, a feasibility study of the BPPM error-correction protocol is performed. The beyond pulse position modulation (BPPM) protocol was invented at Ericsson AB and describes a modulation encoding using vertically and horizontally polarized single photons for optical transmission and error-correction. The thesis work is a mixture of both experimental laboratory work and theoretical software simulations which are intended to mimic actual optical fiber transmission. One aspect of the project work involves designing the optical communication system which is used to evaluate the probabilities of transmission errors in the form of false detections and losses of light. During the project work, the BPPM protocol is implemented and used for software simulated error generation and correction. With the available laboratory setup used as the point of reference, error-correction using the BPPM protocol is studied using pulses of light containing more than one photon. The results show that the BPPM protocol can be used to recover some of the information that is lost during optical fiber transmission. Factors such as the size of the codewords, the number of photons per pulse and detection efficiency of the utilized single photon detector (SPD) have a significant impact on the success of the transmission.

No description available.

Many of todays' sophisticated communication systems, particularly those operating in the microwave frequency range, have a growing demand for highly selective and frequency agile filters with fast tuning rates. At microwave frequencies above 2GHz, filters that combine both tuning speed and high selectivity are difficult to realise. Unloaded Q values in the range of 1000 are required for reasonable selectivity. At present, these requirements with the exception of tuning speed are mainly fulfilled by electronically tuned filters employing yttrium iron garnet (YIG) resonators. An alternative solution to this problem is to utilise high-Q dielectric resonators (DRs) in-conjunction with an appropriate tuning mechanism to realise tunable filters. DRs can provide unloaded Q-factors comparable to waveguide resonators (typically 10,000 @ 10GHz), but at a substantially lower weight and smaller volume. DRs are also compatible with a microstrip environment which eliminates the need for microstrip to waveguide adaptors. This thesis is devoted to the study of the design and realisation of electronically tuned microwave filters employing dielectric resonators. Knowledge of the values of the coupling coefficient between a pair of DRs is essential for the design of both the bandpass and bandstop filters using these resonators. This necessitates the use of an accurate expression for the coupling coefficient which was derived by performing an electromagnetic analysis on the DR structure. This analysis also took into account the effects of the actual circuit environment such as the resonator support spacer and the dimensions of the enclosure. The experimental data presented shows very good agreement with the computed data. Novel techniques for the tuning of the DR operating in its fundamental mode are presented. These tuning configurations incorporating GaAs varactor diodes have been investigated to determine a circuit which greatly perturbs the DR fundamental mode. The amount of tuning that can be obtained by these methods exceeds more than 60MHz of the unperturbed value of resonant frequency with acceptable amount of Q-factor degradation. These tuning characteristics are superior to similar devices reported to date. A simple analytical expression is also derived for determining the tuning range of such a structure. Techniques for the design of novel electronically tunable DR bandpass and bandstop filters having either a Chebyshev or Butterworth response are presented. Design for prescribed response, starting from a low-pass lumped-element prototype filter is outlined. The bandpass filter structure consists of cascaded resonators, with the end resonators coupled to microstrip arcs on a substrate, whereas, the bandstop filter consists of a microstrip line with resonators mounted at intervals of one-quarter-wavelength. Tuning is achieved by varying a bias voltage to the varactor. The measured performances of several practical devices operating in the S-band are presented, these agree closely with theory. The centre frequency of these filters is within 2.46% and the bandwidth is within 3.75% of the desired values.

This thesis describes the in-orbit measurements, design and simulation of error-control strategies and channel modelling for low-Earth orbiting satellites, specifically in a restrictive small satellite platform. The motivation to pursue such a direction is the quest to optimise the low-Earth orbit (LEO) satellite communication link. Until a few years ago, advanced designs for satellite communications systems had focused on conventional geostationary Earth orbit (GEO) communication technologies which are not necessarily tailored to the LEO environment. Such sub-optimal designs were accommodated by the typical application of LEO satellites - remote sensing satellites - normally being large satellites equipped with huge parabolic dishes. With the recent rapid development in numerous LEO satellite constellations and trend in the satellite industry towards smaller and affordable satelhtes, the prominence of satellites in LEO cannot be ignored and it has become crucial to efficiently utilise the communications link. Until now, a suitable channel model for low-Earth orbit satellites has not existed. In order to provide a viable satellite network, a proper knowledge of the dynamic characteristics of the link is essential. A UHF measurement campaign from the UoSAT -3 microsatellite in LEO was therefore undertaken and analysis of the error statistics provides unique information on the channel behaviour for a broad range of elevation angles. The thesis has investigated generative Markov models as a means of representing the observed error statistics and established that the LEO satellite channel can be accurately described by a multiple-good-state, one-error state Fritchman model, or a four-state Markov model under special circumstances which are outlined. Various error control strategies have been evaluated based on the in-orbit measured data and proposed channel models, therefore verifying the precision of the Fritchman and four-state Markov models. During the course of this work, two schemes comprising type-II hybrid-ARQ based on punctured Reed Solomon codes and byte interleaving were investigated and the tradeoffs were identified. A novel type-II + delay hybrid protocol has been proposed and has been demonstrated to provide further increases in throughput performance. The principal conclusion from this thesis is that, using the results of the measurement campaign with an in-orbit satellite, it has been possible to generate a realistic fading model for use in future planning for LEO satellite systems. Furthermore, the type-II, type-II+delay hybrid and byte interleaving techniques are shown to provide an improvement in throughput performance of the existing store-andforward communications protocol with varying tradeoffs between the techniques.

The widespread use of radio frequencies of wavelengths small compared with the major terrain irregularities has led to the development of theoretical deterministic models for the prediction of field strengths over paths of given profile. The examination of these models is the main objective of the present thesis. Although present radio links are mainly based on empirical developments, theoretical approaches may offer considerable alternative for the design of future wireless communications systems. It is well known that the methods applied are based on multidimensional integral equations, which only in certain and idealised cases reduce to a practical form suitable for realistic utilisation. The present work attempts to reveal the physical processes that characterise the radio channel and how these are approached by certain models for common engineering applications. Since the major mechanism of propagation in radio environments is diffraction, extensive analysis is performed for this physical process. In particular, a new fast implementation of the Vogler multiple knife-edge diffraction algorithm is described with the additional benefit of improved accuracy at path profile configurations where the original solution fails considerably. An entirely new approach to slope-Uniform Theory of Diffraction is introduced and shown to produce essentially identical results to Vogler within much shorter computation times. This is applied to 3D urban propagation and to terrestrial fixed links and is shown to produce accurate results compared with measurements. Finally, new physical-statistical models are introduced in order to overcome the excessive cost of high resolution building databases. Application to both mobilesatellite and to broadband fixed access systems revealed a high degree of statistical accuracy

This work is motivated by the current trends in future broadband communication networks. On the one hand, the latest developments and experimentation with the Asynchronous Transfer mode (ATM) technology shows that that ATM is going to be the future transport mechanism in many private and public networks. This is driven by the need to efficiently support a large population of widebandlbroadband users with different data traffic characteristics and certain Quality of Service (QoS) guarantees. On the other hand, the interest in satellites and their role in the future broadband multimedia communications systems, has grown considerably since they can very quickly and economically extend the boundaries of the terrestrial mobile and fixed networks coverage. On-board satellite signal regeneration and' ATM-like' switching is part of the latest experimental developments by many payload manufacturers. In this thesis, the focus is on the Grade of Service (GoS) and QoS provisioning in future broadband satellite multimedia systems by introducing new means for their performance evaluation. The investigation includes modelling techniques for both Geostationary (GEO) and non-GEO systems. An extensive set of representative results derived analytically and by simulation are presented assuming different mixed traffic scenarios. A new methodology for the Available Bit Rate (ABR) service class capacity estimation and the CAC strategy that needs to be adopted in S-ATM systems is developed. Moreover, the performance evaluation of bandwidth reservation techniques for non-GEO satellite constellations is investigated and new rules for maintaining specified GoS performance are proposed. This work contributes towards the definition of a satellite network infrastructure that best satisfies the requirements of an integrated solution with Broadband-Integrated Services Digital Network (B-ISDN).

The present thesis discusses the interrelation between technical change, institutional transformation and public policy in the context of the planning and early development of new public telecommunications infrastructures. Efforts to implement ISDN have featured prominently in the above developments during the 1980s, thus offering the empirical ground on which the thesis focuses. Specifically, the thesis aims to identify the main critical factors that have been shaping the realisation of ISDN nationally and internationally and assess their impact in its early commercialisation stage. A number of analytical concepts provide the background for the above exercise: the Schumpeterian "creative destruction" and its variants; the notion of complementarity between technical change and institutional restructuring; different classifications of the innovation process; the ideas of technological paradigms and trajectories; the role of user-producer relations. ISDN is assessed in view of the broader transformations that have revolutionised the telecommunications industry during the 1980s. The innovative record of "technical trends" and socio-technical "concepts" examined by the thesis supports the case for technological pluralism. Their presence opens a variety of implementation alternatives for policy makers and defies the technological determinism strongly present in the original versions of the ISDN concept. Moreover, the spectrum of liberalisation regulatory options analysed, creates radically different conditions for the realisation of ISDN from the monopoly environment it was conceived in. As a result, ISDN is forced to change, adapting to a competitive, "open network" environment. The thesis examines the specific experiences of ISDN implementation in the United States, Japan and the European Community (France, Germany and the U.K., plus policies promoted by the European Commission) for its early diffusion period (up to 1990). It is demonstrated that ISDN has been pushed by telecommunications suppliers as part of both their longer-term strategic plans as well as their shorter-term tactical moves. Yet supply push, including international standardisation efforts, has been unable to offer success alone. A weak user participation, later realised by some providers; a slow and complex adaptation of ISDN to the new regulatory realities; difficulties to identify "winning" commercial applications for the right markets. These are the most important problem factors in ISDN's smooth commercialisation, although with varying impact in different national environments.