A powerful technique is presented for joint blind channel estimation and carrier offset method for code- division multiple access (CDMA) communication systems. The new technique combines singular value decomposition (SVD) analysis with carrier offset parameter. Current blind methods sustain a high computational complexity as they require the computation of a large SVD twice, and they are sensitive to accurate knowledge of the noise subspace rank. The proposed method overcomes both problems by computing the SVD only once. Extensive simulations using MatLab demonstrate the robustness of the proposed scheme and its performance is comparable to other existing SVD techniques with significant lower computational as much as 70% cost because it does not require knowledge of the rank of the noise sub-space. Also a kernel based equalization for CDMA communication systems is proposed, designed and simulated using MatLab. The proposed method in CDMA systems overcomes all other methods.

This research investigates mobile service design and engineering in the mobile telecommunications industry. The mobile telecommunication business is shifting from one that was voice-centric to one that is almost all data-centric; thanks to recent rapid advances in Information and Communication Technologies (ICTs). The underlying reasons behind this shift can be traced back to two main issues that are interlinked. The first and major reason is that telecoms (telecommunication companies) are trying to generate new revenue streams based on data and information transmissions, given the saturation of the voice market. This is rational given the market opportunities in one direction and the pressures being generated by the current economic downturn from the other direction. The second reason relates to the flexibility of data, compared to voice. Indeed, the number of services that can be developed on the basis of data are much greater than those that can be developed on the basis of voice. However, the design and engineering of successful and innovative mobile data services has proven to be a complex undertaking. The number of effective mobile data services is relatively small and the revenue generated from such offerings has generally been below expectations. This research develops an ontological framework to help in changing this situation, and making mobile services engineering more effective and successful, following the design-science research paradigm. Design-science research, in general, aims to solve unstructured but relevant organizational or social problems through the development of novel and useful artefacts. As the current research aims to help in solving the mobile data services engineering dilemma by developing a purposeful ontological framework, the design-science research paradigm is deemed fitting. Within this paradigm, the author develops a novel design approach specified for ontology engineering, termed “OntoEng”. This design approach is used in this research for developing the ontological framework. The developed ontological framework is founded on business model thinking. The idea is that creating innovative mobile data services requires developing innovative business models. Indeed, innovative business models can help translate technological potential into economic value and allow telecoms to achieve their strategic objectives. The ontological framework includes the development of an ontology, termed “V4 Mobile Service BM Ontology” as well as “Mobile Key Value Drivers” for designing and engineering innovative mobile data services. The V4 Mobile Service BM Ontology incorporates four design dimensions: (1) value proposition including targeting; (2) value architecture including technological and organizational infrastructure; (3) value network dealing with aspects relating to partnerships and co-operations; and finally (4) value finance relating to costs, pricing, and revenue structures. Within these four dimensions, sixteen design concepts are identified along with their constituent elements. Relationships and interdependencies amongst the identified design constructs are established and clear semantics are produced. The research then derives six key value drivers for mobile service engineering as follows: (a) Market Alignment; (b) Cohesion; (c) Dynamicity; (d) Uniqueness; (e) Fitting Network-Mode; and (f) Explicitness. The developed ontological framework in this research is evaluated to ensure that it can be successfully implemented and performs correctly in the real world. The research mainly utilizes case analysis methods to ensure the semantic correctness of the ontological framework. Indeed, the developed ontological framework is employed as an analytical lens to examine the design and engineering of three key real-life cases in the mobile telecommunications industry. These cases are: (1) Apple’s iPhone Services and Applications; (2) NTT DoCoMo’s i-mode Services; and (3) Orange Business Services. For further validation, the developed ontological framework is evaluated against a set of criteria synthesized from ontology engineering and evaluation literature. These criteria are: Clarity; Coherence; Conciseness; Preciseness; Completeness; and Customizability. The developed ontological framework is argued to make significant contributions for theory, practice, and methodology. For theory, this research provides (1) a novel ontological framework for designing and engineering mobile data services; (2) a unified framework of the business model concept; and (3) a new design approach for ontology engineering in information systems. For practice, the current research provides practitioners in the telecommunications industry with systematic and customizable means to design, implement, analyze, evaluate, and change new and existing mobile data services to make them more manageable, effective, and creative. For methodology, the use of the design- science research paradigm for ontology engineering signifies the focal methodological contribution in this research given its novelty. This research also contributes to the understanding of the design-science research paradigm in information systems as it is relatively new. It provides a working example in which the author illustrates how recognizing design-science research as a paradigm is essential and useful to the research in information systems discipline.

A common issue with the power grid during natural disasters is low availability. Many critical applications that are required during and after natural disasters, for rescue and logistical operations require highly available power supplies. Microgrids with distributed generation resources along with the grid provide promising solutions in order to improve the availability of power supply during natural disasters. However, distributed generators (DGs) such as diesel gensets depend on lifelines such as transportation networks whose behavior during disasters affects the genset fuel delivery systems and as a result affect the availability. Renewable sources depend on natural phenomena that have both deterministic as well as stochastic aspects to their behavior, which usually results in high variability in the output. Therefore DGs require energy storage in order to make them dispatchable sources. The microgrids availability depends on the availability characteristics of its distributed generators and energy storage and their dependent infrastructure, the distribution architecture and the power electronic interfaces. This dissertation presents models to evaluate the availability of power supply from the various distributed energy resources of a microgrid during natural disasters. The stochastic behavior of the distributed generators, storage and interfaces are modeled using Markov processes and the effect of the distribution network on availability is also considered. The presented models supported by empirical data can be hence used for microgrid planning. / text

The electrical efficiency of telecommunication power supplies is increasing to meet customer demands for lower total cost of ownership. Increased capital cost can now be justified if it enables sufficiently large energy savings, allowing the use of topologies and devices previously considered unnecessarily complex or expensive. Silicon carbide Schottky diodes have already been incorporated into commercial power supplies as expensive, but energy saving components. This thesis pursues the next step of considering silicon carbide transistors for use in telecommunications power converters. A range of silicon carbide transistors was considered with a primary focus on recently developed, normally-off, junction field effect transistors. Tests were devised and performed to uncover a number of previously unpublished characteristics of normally-off silicon carbide JFETs. Specifically, unique reverse conduction and associated gate current draw relationships were measured as well as the ability to block small reverse voltages when a negative gate-source voltage is applied. Reverse recovery-like characteristics were also measured and found to be superior to those of silicon MOSFETs. These characteristics significantly impact the steps that are required to maximize efficiency with normally-off SiC JFETs in circuits where synchronous rectification or bidirectional blocking is performed. A gate drive circuit was proposed that combines a number of recommendations to achieve rapid and efficient switching of normally-off SiC JFETs. Specifically, a low transient output impedance was provided to achieve rapid turn-on and turn-off transitions as well as a high dc output impedance to limit the steady state drive current while sustaining the turned-on state. A prototype circuit was constructed using building blocks that are typically found in single chip MOSFET drivers. The circuit was shown to operate well from a single supply, alleviating the need for a split supply such as that required by many published JFET drive circuits. This demonstrated a proof of concept for a single chip JFET driver solution. An active power factor correction circuit topology was extensively modelled and a prototype designed and tested to verify the model. The circuit was able to operate at switching frequencies in excess of 100kHz when using SiC JFETs, whereas silicon MOSFETs could only achieve switching frequencies of several kHz before switching losses became excessive. The circuit was designed as the dc equivalent for a 2kW, 230V AC input power converter with a split +/-400V dc output. A commercial single phase telecommunications power converter was modified to utilise normally-off SiC JFETs in its power factor correction circuit. The converter was tested and found to achieve similar electrical efficiency with 1200V SiC JFETs to that achieved with 600V silicon MOSFETs. The performance of the 1200V SiC JFETs in this application was also compared to that of 900V silicon MOSFETs and found to be superior. Finally, a prototype three-phase cyclo-converter was modified to use 1200V normallyoff SiC JFETs in place of 600V silicon MOSFETs and found to achieve similar electrical efficiency to the silicon MOSFETs in a 208V three phase system. These results strongly indicate that the 1200V SiC JFETs would provide better performance than 900V silicon MOSFETs in a 400V three phase system (that had been considered for commercial development).

In the two years 1989-1991 the environment of Poland's telecommunications was fundamentally transformed. This dissertation is an exploratory case study addressing four principal aspects of that country's changing telecommunications: (1) telecommunication regime or the structure of rules in which telecommunication systems function; (2) telecommunication services, defined as the means and methods of communicating from a distance by processing and relaying an electro-magnetic signal (categorized into telephone, mobile, data-messaging, information, data-carrier, and entertainment); (3) telecommunication equipment, or markets for switching, transmission and terminal equipment; and (4) telecommunication subscribers, or principal characteristics of the customer-base in the residential, professional, rural and urban market segments. Each aspect is examined for the purpose of capturing the on-going change. The dissertation identifies the principal agents of change and maps the new conditions onto the models developed by Cowhey and Aronson. Institutional pluralism, market competition, shortage alleviation and market restructuring have transformed Poland's telecommunication environment from the scarcity model to a version of the boutique model.

The objective of this research is to design, and determine the feasibility of, a telecommunication system for the city of Erdenet, Mongolia. The Mongolian Telecommunication Company, Telecommunication Company of Erdenet city, and the National Statistical Office of Mongolia provided the data required for telecommunication forecasting of Erdenet. The literature review and analysis of the telecommunication forecasting indicate the need for a model of a new Telecommunication system in Erdenet, Mongolia. The model, as indicated, should become a useful example for planning and updating the telecommunication system in Mongolia. The design of a proposed telecommunication network involves the following considerations: analyzing and forecasting telephone traffic, calculating the required number of channels, determining exchange locations, traffic matrix, and establishing a basic hierarchical structure.

The new released 4G standard wireless communication reminds us that higher transmission data rate and more reliable service are required urgently. However, to fulfill the demand can face problems in a complex environment like mines. In this thesis, characterization of underground tunnel mines with the idea of combating intersymbol interference effect is presented.            Ray tracing simulation method is applied to characterize channel impulse response in different positions of an underground tunnel. From this channel impulse response, we can obtain how intersymbol interference affects different wireless systems. Intersymbol interference occurs due to multipath propagation of time dispersion channel.           Adaptive Equalization is the most effective way to compensate intersymbol interference. Adaptive filter adapts filter coefficients to compensate the channel so that the combination of the filter and channel offers a flat frequency response and linear phase. The bit error rate performance without using adaptive equalization is compared with using equalizer. Moreover, adaptive equalization approaches using RLS and LMS algorithms are compared with each other. The tradeoff between convergence rate, computation cost instability and ensemble averaged minimum squared errors are analyzed to determine how to select the optimum adaptive equalizer.

This thesis evaluated the requirement and provides course improvement recommendations forTelecommunications Systems Engineering EO3502 taught at the Naval Postgraduate School Other graduate programs in Information Technology Management were evaluated to determine the standard for telecommunications engineering expected from some of the most respected academic institutions. Graduates of NPS's Information Technology Management (ITM) and Information Systems andOperations (ISO) curriculums were surveyed to determine how important telecommunicationsengineering is for their follow-on assignments. In addition, lesson topic vignettes were developed toprovide fleet/field examples to reinforce the relevance if individual topics. Finally, recommendationswere provided for improving EO3502 and the ITM curriculum in general. / Approved for public release; distribution is unlimited

The work presented in this thesis fits within the broader area of fiber optics communications. This is an important area of research as it provides a breeding ground for the present and future technologies supporting the Internet. Due to the ever-increasing bandwidth demands worldwide, the network infrastructures that make up the Internet are continuously being upgraded. This thesis aims to identify key segments of the Internet that are deemed to become the Internet's bottleneck if new technology does not replace the current one. These are datacenter intra and inter-connects, and metropolitan core area networks. In each category, we provide a comprehensive overview of the state of the art, identify key impairments affecting data transmission, and suggest solutions to overcome them.   For datacenter intra and inter-connects, the key impairments are lack of bandwidth from electro-optic devices, and dispersion. Solutions attempting to tackle these impairments must be constrained by cost and power consumption. The provided solution is MultiCAP, an alternative advanced modulation format that is more tolerable to dispersion and provides bandwidth management features, while being flexible enough to sacrifice performance in order to gain simplicity. MultiCAP was the first advanced modulation format to achieve over 100~Gb/s in 2013 for a data-center interconnect and set the world record on data transmission over a single VCSEL in 2014 for a short reach data link.    On metro-core networks, the challenge is to efficiently mitigate carrier induced frequency noise generated by modern semiconductor lasers. We point out that, when such lasers are employed, the commonly used laser linewidth fails to estimate system performance, and we propose an alternative figure of merit we name "Effective Linewidth". We derive this figure of merit analytically, explore it by numerical simulations and experimentally validate our results by transmitting a 28~Gbaud DP-16QAM over an optical link. / <p>QC 20170602</p> / GRIFFON

M.Ing. / Application Layer Forward Error Correction (AL-FEC) is a relatively new concept which uses erasure codes to add reliability insurance to particular application streams on a network. This concept has become particularly popular for media streaming services. Fountain codes have shown promise as the erasure code of choice for these implementations. The Fountain code concept is a principle that has two popular instantiations, the Luby Transform (LT) code and the Raptor code. While the Raptor code is the more efficient of the two, the LT code is the focal point of our dissertation. Our main objective in this dissertation was broken up into two different primary objectives which we had to satisfy in its completion. The first of these primary objectives entailed the finding of sets of input parameters which would yield an optimal implementation of the LT code for a given set of input block sizes. The simulation work performed in this investigation was done on a wide range of input parameters for each input block size concerned. While there have been a number of other studies which have performed such parameter optimisation we have not found any that present such comprehensive results as we do. The second of the primary objectives related to the analysis of the code when applied as an AL-FEC reliability mechanism for streaming media. This simulation work was performed on simulated IP network environments using the NS2 network simulator. The codes which were applied to the network were based on the optimal parameter sets found in the first objective. We analysed the effective throughput achievable by the code in the face of various packet loss rates. With the data obtained from the simulations we then derived a constraint on the allowable bit-rate of media which uses the LT code as an AL-FEC reliability mechanism. In performing the work in this dissertation it was identified that it was required to develop the LT code related simulation tools for performing the respective investigations. This involved development of a stand-alone LT code simulator as well as an LT code AL-FEC reliability mechanism for NS2.