Thesis (M.B.A.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 56).

published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

The object of interest in this research is the evaluation of the combined routing and flow control scheme proposed by Muralidhar and Sundareshan. A slightly modified design using results from positive system theory is proposed as an attempt to improve the performance. Then a detailed performance evaluation of Muralidhar and Sundareshan's scheme and its modified version proposed here is conducted using discrete-event simulation. The application of positive system theory to the combined routing and flow control algorithm proposed by Muralidhar and Sundareshan proved to be quite effective in improving the overall performance only in the initial transient period. The fact that the improvement is restricted to a particular time period appears to be attributable to poor buffer management and certain other fundamental problems with Muralidhar and Sundareshan's scheme. These problems are identified and are described in detail.

Approved for public release; distribution is unlimited / Future underwater missions will require data transmission via satellite. In particular, the Office of Naval Research (ONR) is interested in experimenting with communications using the GOES satellite system, which is government owned. Unfortunately, communication antennas must point to specific satellites in this system and thus underwater vehicles must steer a specific course on the surface during the communication process. While surfaced, underwater vehicles are subject to wind and wave disturbances and it has been suggested that control using differential thrust from propellers may provide advantages. This thesis covers efforts to create and test such a steering autopilot based on the use of the ARIES AUV and differing the voltage supplied to each propeller. It is planned to use the ARIES in an ocean experiment to test this satellite communication capability. This control is embedded in the control of ARIES during extended pop up maneuvers for GPS navigational fixes. When surfaced, not only are navigational fixes obtained, but also data packets are communicated to a command center. / Lieutenant, United States Navy

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering / This dissertation verifies a Computer Simulation Package for modeling pulse transmission over digital subscriber loops. Multigauge sections on subscriber cables can be studied. The model used for each section incorporates skin, proximity and eddy current effects. The model allows important quantities such as near end echo and overall transmission distortion of pulses to be.predicted. An experimental facility has been established in the laboratory for the purpose of validating the results produced by the simulator with results obtained over real cables. The experimental facility has as far as possible been automated by making use of computer controlled equipment for direct setup or the experiment, data transfer, and analysis. The results obtained from the pulse propagation program and that obtained from measurements are in close. agreement, rendering the Computer Simulation Package useful for analysing the performance of multi gauge digital subscriber loops. / AC 2018

Chui Sai Kit. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 73-77). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Wireless LAN --- p.3 / Chapter 1.2.1 --- Ad Hoc Mode --- p.3 / Chapter 1.2.2 --- Infrastructure Mode --- p.3 / Chapter 1.3 --- Handoff --- p.4 / Chapter 1.3.1 --- IP Layer Handoff --- p.5 / Chapter 1.3.2 --- MAC Layer Handoff --- p.6 / Chapter 1.4 --- Voice over Internet Protocol (VoIP) --- p.6 / Chapter 1.5 --- Significance of Research Outcomes --- p.8 / Chapter 1.6 --- Outline of Thesis --- p.10 / Chapter 2 --- Background Study --- p.11 / Chapter 2.1 --- Handoff Process --- p.12 / Chapter 2.2 --- MAC Layer Handoff --- p.12 / Chapter 2.2.1 --- MAC Layer Handoff Process --- p.12 / Chapter 2.2.2 --- MAC Layer Handoff Scheme --- p.16 / Chapter 2.3 --- IP Layer Handoff --- p.20 / Chapter 2.3.1 --- IP Layer Handoff Process --- p.20 / Chapter 2.3.2 --- IP Layer Handoff Scheme --- p.22 / Chapter 2.4 --- Chapter Summary --- p.25 / Chapter 3 --- AP Coordination System and Performance Analysis for Sync-Scan --- p.26 / Chapter 3.1 --- Introduction --- p.26 / Chapter 3.2 --- Problem Formulation --- p.27 / Chapter 3.3 --- Fast Handoff Scheme --- p.27 / Chapter 3.3.1 --- Access Point Coordination System --- p.28 / Chapter 3.3.2 --- Simulation Results --- p.30 / Chapter 3.3.3 --- Further Discussion --- p.33 / Chapter 3.3.4 --- Improved Handoff Process --- p.34 / Chapter 3.4 --- SyncScan Performance Analysis --- p.36 / Chapter 3.4.1 --- Beacon Delay --- p.36 / Chapter 3.4.2 --- Handoff Latency --- p.38 / Chapter 3.5 --- Chapter Summary --- p.41 / Chapter 4 --- Handoff Control Message Analysis --- p.43 / Chapter 4.1 --- Introduction --- p.43 / Chapter 4.2 --- Problem Formulation --- p.44 / Chapter 4.3 --- Key System Parameters --- p.45 / Chapter 4.4 --- System Model --- p.47 / Chapter 4.4.1 --- Markov Modulated Poisson Process (MMPP) Model --- p.47 / Chapter 4.4.2 --- System Time Distribution --- p.52 / Chapter 4.5 --- Performance Analysis --- p.58 / Chapter 4.6 --- Further Discussion --- p.63 / Chapter 4.6.1 --- Handoff Scheme Strategy --- p.63 / Chapter 4.6.2 --- Channel Reservation for Handoff Process --- p.66 / Chapter 4.7 --- Chapter Summary --- p.68 / Chapter 5 --- Conclusion --- p.70 / Bibliography --- p.73

by Gao Yan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 62-[65]). / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Purpose of Study --- p.5 / Chapter 1.3 --- Organization of Chapters --- p.7 / Chapter 2 --- Overview of Optical Burst-Mode Receivers --- p.8 / Chapter 2.1 --- Introduction --- p.8 / Chapter 2.2 --- Burst-Mode Data Transmission --- p.9 / Chapter 2.3 --- Two Main Issues on Burst-Mode Receiver --- p.11 / Chapter 2.4 --- Model of Burst-Mode Receiver --- p.13 / Chapter 2.5 --- Threshold Detection in Burst-Mode Receiver --- p.16 / Chapter 2.6 --- Sensitivity Penalty in Burst-Mode Receiver --- p.20 / Chapter 2.7 --- Chapter Summary --- p.22 / Chapter 3 --- Optimal Detection Threshold in Burst-mode Receiver --- p.24 / Chapter 3.1 --- Introduction --- p.24 / Chapter 3.2 --- Threshold Fluctuation in Burst-Mode Receiver --- p.25 / Chapter 3.3 --- BER of Burst-Mode Receiver --- p.27 / Chapter 3.4 --- Optimal Detection Threshold of Burst-Mode Receivers --- p.31 / Chapter 3.5 --- Simulation Result on the BER of Burst-mode Receiver --- p.36 / Chapter 3.6 --- Chapter Summary --- p.38 / Chapter 4 --- MLT-3 Burst-Mode Receiver --- p.41 / Chapter 4.1 --- Introduction --- p.41 / Chapter 4.2 --- MLT-3 Line Code --- p.42 / Chapter 4.3 --- BER Performance of MLT-3 Continuous-Mode Receiver --- p.45 / Chapter 4.4 --- Burst-mode Receiver For MLT-3 Line Code --- p.49 / Chapter 4.5 --- BER Performance of MLT-3 Burst-Mode Receiver --- p.52 / Chapter 4.6 --- Chapter Summary --- p.55 / Chapter 5 --- Conclusion --- p.59 / Bibliography --- p.62

Data communication is a critical component of modern technology in our society. There is an increasing reliance on information being at our fingers tips and we expect a low-latency, high-bandwidth connection to deliver entertainment or enhanced productivity. In order to serve this demand, communications devices are being pressed for smaller form factors, higher data throughput, lower power consumption and lower cost. Similar demands exist in a number of applications including metro/long-haul telecommunications, shorter datacenter links and supercomputing. Silicon photonics promises to be a technology that will solve some of the difficulties with improving communication devices. Building photonics in silicon allows for reuse of the same fabrication technology that is used by the CMOS electronics industry, potentially allowing for large volumes, high yields and low costs. Part I of this thesis details the design of components needed in a high-speed silicon photonic platform to meet the current challenges for high-speed communications. The author’s work in modeling photodetectors resulted in improving photodetector bandwidth from 30 GHz to 67 GHz, the fastest reported at the time of publication. Details regarding the optimization and test of modulators are also presented with the first-reported 50 Gbps modulator at 1310-nm. A large scale parallel channel demonstration of high-speed silicon photonics is then presented showing the potential scalability for silicon photonics systems. A full transceiver requires a number of components other than the photodetector and modulator that are the core active pieces of a silicon photonics platform. Part II includes work on the design and test of silicon photonic components providing functionality beyond the photodetector and modulator. A novel design integrating Metal-Semiconductor Field Effect Transistors (MESFETs) into a silicon photonics platform without process change is shown. This integration enables enhanced control functionality with minimal overhead. The critical final piece for a silicon photonics platform, adding a light source, is demonstrated along with performance results of the resulting tunable, extended C-band laser. In Part III, previous work on an enhanced silicon photonics platform with complementary components is used to build a high-speed integrated coherent link and then tested with a silicon photonics-based tunable laser. The transceiver was shown to operate at 34 Gbaud dual-polarization 16-QAM for a total of 272 Gbps over a single channel. This was the first published demonstration of an integrated coherent where all of the optics were built in a silicon photonics platform.

This dissertation investigates the use of a hardware mechanism called Eager Data Transfer (EDT) for achieving the reduction of communication latency for user-level network protocol. To reach the goal, the dissertation addresses the following research issues. First, the development of a communication system performance evaluation tool called Linux/SimOS is presented. Linux/SimOS provides a full system profiling capability to allow measurement at various level including hardware, operating system, and application. Second, the performance analysis of network protocols is presented. For the assessment of overhead related to network protocol operation, Linux/SimOS was used to perform the detailed latency measurements for TCP/IP, UDP/IP, and M-VIA network protocols. Finally, EDT is proposed for reducing communication latency. Since the data transfer time constitutes a significant portion of overall communication latency, the reduction of data transfer time leads to low communication latency. EDT is based on cache coherence interface hardware for reducing data transfer overhead during network protocol operation. Our simulation result shows that EDT is very effective in attaining low communication latency compared to the DMA-based approaches. / Graduation date: 2005

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.