The use of electrical networks for telecommunications has a long history. It has been known since the beginning of the twentieth century [Ahola03]. The idea of using electrical networks for broadband communications arose in the 1990s [Hrasnica et al 04]. Recent and growing research interest has indicated that PowerLine Communications (PLC) is the threshold for achieving broadband delivery particularly in very dispersed and low teledensity areas. Currently, there are numerous PLC trials and commercial deployments underway inside and outside South Africa. Nevertheless, these PLC deployments are very isolated, done without clear methodology and performance remains bound to the physical layout of the electrical network. Because of that high bandwidth broadband PLC systems are prone to poor performance and this in turn limits the acceptance and deployment of this emerging alternative broadband technology. Though, PLC technical challenges are being addressed, there has been little analysis and research work that is focused on the “Development of Methodologies for Deploying and Implementing Local & Medium Area Broadband Power Line in Residential and Office Electric Grids” that would lead to broadband PLC being adopted and be of greater use to non-broadband communities of South Africa. PLC is a term describing several different systems using electrical grid distribution wires for simultaneous distribution of data by superimposing an analog signal [Hrasnica et al 04]. The research proposed and presented broadband PLC methodologies for typical medium voltage and local voltage PLC networks. These methodologieswere implemented and experimented with in configurations which closely mirrored residential and office settings through laboratory and multibuilding experiments using commercial 2nd Generation Mitsubishi Electric PLC technology. Research results presented not only serve to provide insight into broadband PLC but also how it handled broadband applications (communications), competed and compared with other technologies such as Ethernet LAN. In combination with networking communication theories, the research explored and analyzed the extent of PLC in providing broadband communication to residential and office electric grids at the University Fort Hare, Computer Science Department.

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The ever-growing demand for higher bandwidth broadband communication has driven transistor operation to higher and higher frequencies. However, achieving cut-o frequencies in the terahertz regime have been unsuccessful with the current state-of-the-art transistors exhibiting no better than 800 GHz. While the high-frequency transistor eld is dominated by III-V semiconductors, it has been proposed that graphene may be a competitive material. Graphene exhibits electron and hole mobilities orders of magnitude larger than conventional semiconductors and has an atomically thin form factor. Despite these benets, high-frequency graphene transis tors have yet to realize high-frequency characteristics better than III-V's. This thesis expands on the current limitations of graphene transistors in terms of improved fabrication techniques (to achieve higher carrier mobilities and lower contact resistances) and fundamental, band structure limitations (like quantum capacitance and the zero energy band gap). First, graphene, fully encapsulated in hexagonal boron-nitride crystals, transistors are fabricated with self-aligned source and drain contacts with sub-100 nm gate lengths. The encapsulation technique shields the graphene from the external environment so that graphene retains its intrinsic high mobility characteristic. In this short-channel regime, transport is determined to be ballistic with an injection velocity close to the Fermi velocity of graphene. However, the transconductance and output conductance are only 0.6 mS/mm and 0.3 mS/mm, respectively. This lack-luster performance is due to a relatively thick (3.5 nm) eective oxide thickness but also due to the eects of quantum capacitance which diminishes the total gate capacitance by up to 60%. Furthermore, the output conductance is increased due to the onset of hole conduction which leads to a second linear regime in the I-V characteristic. This is a direct consequence of graphene's zero energy band gap electronic structure. Finally, the source and drain contact resistances are large, which leads to poorer output current, transconductance and output conductance. Second, improvement to the contact resistance is explored by means of using graphite as the contact metal to graphene. Since graphite is atomically smooth, a pristine graphite-graphene interface can be formed without grain asperities found in conventional metals. Graphite is also lattice matched to graphene and exhibits the same 60 symmetry. Consequently, it is discovered that the graphite-graphene contact resistance exhibits a 60 periodicity, with respect to crystal orientation. When the two lattices align, a contact resistivity under 10 Wmm² is observed. Furthermore, contact resistivity minima are observed at two of the commensurate angles of twisted bilayer graphene. Though graphene transistor performance is band structure limited, it may still be possible to achieve competitive high-frequency operation by use of h-BN encapsulation and graphite contacts.

Thesis (Ph. D.)--University of California, San Diego, 2010. / Title from first page of PDF file (viewed Feb. 22, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 421-450).

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (M.B.A.)--University of Hong Kong, 1998. / Includes bibliographical references (leaf 99-100).

Thesis (M.A.)--Eastern Illinois University, 2010. / Includes bibliographical references (leaves 72-79).

M.Phil. (Electrical & Electronic Engineering) / Without any doubt, the entire range of voice and TV signals will migrate to the packet network. The universal addressable mode of Internet protocol (IP) and the interfacing framing structure of Ethernet are the main reasons behind the success of TCP/IP and Ethernet as a packet network and network access scheme mechanisms. Unfortunately, the success of the Internet has been the problem for real-time traffic such as voice, leading to more studies in the domain of Teletraffic Engineering; and the lack of a resource reservation mechanism in Ethernet, which constitutes a huge problem as switching system mechanism, have raised enough challenges for such a migration. In that context, ITU-T has released a series of Recommendation under the umbrella of H.323 to guarantee the required Quality of Service (QoS) for such services. Although the “utilisation” is not a good parameter in terms of traffic and QoS, we are here in proposing a multiplexing scheme with a queuing solution that takes into account the positive correlations of the packet arrival process experienced at the multiplexer input with the aim to optimize the utilisation of the buffer and bandwidth on the one hand; and the ITU-T H.323 Endpoints and Terminals configuration that can sustain such a multiplexing scheme on the other hand. We take into account the solution of the models from the M/M/1 up to G/G/1 queues based on Kolmogorov’s analysis as our solution to provide a better justification of our approach. This solution, the Diffusion approximation, is the limit of the Fluid process that has not been used enough as queuing solution in the domain of networking. Driven by the results of the Fluid method, and the resulting Gaussian distribution from the Diffusion approximation, the application of the asymptotic properties of the Maximum Likelihood Estimation (MLE) as the central limit theorem allowed capturing the fluctuations and therefore filtering out the positive correlations in the queue system. This has resulted in a queue system able to serve 1 erlang (100% of transmission link capacity) of traffic intensity without any extra delay and a queue length which is 60% of buffer utilization when compared to the ordinary Poisson queue length.

Leung, Yiu-Wing. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references (leaves 150-157). / Acknowledgments / Abstract / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Broadband Video Services --- p.1 / Chapter 1.3 --- Videoconference Services --- p.7 / Chapter 1.4 --- Videoconference Systems --- p.8 / Chapter 1.5 --- Chapter Summary and Thesis Organization --- p.18 / Chapter Chapter 2 --- Efficient Algorithms for Multiple Destinations Routing --- p.20 / Chapter 2.1 --- Background --- p.20 / Chapter 2.2 --- Integer Programming Formulation of the MDR Problem --- p.26 / Chapter 2.3 --- Heuristics for Multiple Destinations Routing --- p.27 / Chapter 2.4 --- Performance Comparisons --- p.40 / Chapter 2.5 --- Chapter Summary --- p.50 / Chapter Chapter 3 --- Connection Optimization for Two Types of Videoconferences --- p.51 / Chapter 3.1 --- Background --- p.51 / Chapter 3.2 --- The Videoconference Services --- p.52 / Chapter 3.3 --- Connection Optimization --- p.54 / Chapter 3.4 --- Performance Analysis --- p.62 / Chapter 3.5 --- Chapter Summary --- p.80 / Chapter Chapter 4 --- A TDM-based Multibus Packet Switch --- p.81 / Chapter 4.1 --- Background --- p.81 / Chapter 4.2 --- Architecture of the Multibus Switch --- p.89 / Chapter 4.3 --- Operation of the Multibus Switch --- p.93 / Chapter 4.4 --- Performance Analysis --- p.95 / Chapter 4.5 --- Numerical Results --- p.106 / Chapter 4.6 --- Discussions --- p.109 / Chapter 4.7 --- Chapter Summary --- p.113 / Chapter Chapter 5 --- A Modular Shared Media Video Switch --- p.114 / Chapter 5.1 --- System Architecture and Operation --- p.114 / Chapter 5.2 --- Slot Assignment for Point-to-Point Transmissions --- p.129 / Chapter 5.3 --- Slot Assignment for Point-to-Multipoint Transmissions --- p.132 / Chapter 5.4 --- Network Design Example --- p.136 / Chapter 5.5 --- Chapter Summary --- p.143 / Appendix --- p.144 / Chapter Chapter 6 --- Conclusions --- p.147 / References --- p.150

An Zhuo. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 62-65). / Abstracts in English and Chinese. / Acknowledgments --- p.i / 摘要 --- p.ii / Abstract --- p.iii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Circuit switching and Packet switching --- p.2 / Chapter 1.2 --- Virtual paths in high-speed networks --- p.6 / Chapter 1.3 --- BEF in cross-path switch --- p.8 / Chapter 1.4 --- Organization --- p.11 / Chapter Chapter 2 --- Analysis models --- p.12 / Chapter 2.1 --- Routing schemes in Clos network --- p.12 / Chapter 2.2 --- Path Switching --- p.15 / Chapter 2.3 --- Traffic Model of Input Modules --- p.17 / Chapter 2.4 --- Traffic Model of Output Modules --- p.19 / Chapter 2.5 --- Summary --- p.23 / Chapter Chapter 3 --- Throughput Performance of Input Modules in Path Switching --- p.24 / Chapter 3.1 --- Throughput performance vs. BEF --- p.24 / Chapter 3.2 --- Throughput performance vs. number of virtual paths --- p.30 / Chapter 3.2.1 --- Throughput performance vs. integer group size m/k --- p.33 / Chapter 3.2.2 --- Throughput performance vs. group size 0<R<2 --- p.39 / Chapter 3.2.3 --- Throughput performance vs. look-ahead scheme window size ω --- p.46 / Chapter 3.3 --- Summary --- p.48 / Chapter Chapter 4 --- Traffic Balancing Control in Path Switching --- p.50 / Chapter 4.1 --- Loss Probability in Output Modules --- p.50 / Chapter 4.1.1 --- Loss probability vs. number of central modules m --- p.51 / Chapter 4.1.2 --- Loss probability vs. knockout group size R and cluster size g --- p.52 / Chapter 4.2 --- Simulation Comparison of look-ahead scheme --- p.53 / Chapter 4.3 --- Simulation result of throughput vs. BEF --- p.55 / Chapter 4.4 --- Traffic Balancing Control --- p.55 / Chapter 4.5 --- Summary --- p.53 / Chapter Chapter 5 --- Conclusion --- p.60 / Bibliography --- p.62