by Chan Kwok-sum, Mak Wai-sing. / Bibliography: leaves 85-86 / Thesis (M.B.A.)--Chinese University of Hong Kong, 1986

Xie, Zhenchang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (p. 48-50). / Abstracts in English and Chinese. / Abstract --- p.ii / Table of Contents --- p.v / List of Figures --- p.vi / List of Tables --- p.vii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Development of fiber optic networks --- p.1 / Chapter 1.2 --- Optical transmission system --- p.2 / Chapter 1.3 --- The motivation of this thesis --- p.7 / Chapter 1.4 --- Outline of this thesis --- p.8 / Chapter Chapter 2 --- The Consolidation of Two Coexisting Networks with Full-Interconnection --- p.10 / Chapter 2.1 --- Assumptions and problem formulation --- p.10 / Chapter 2.2 --- Definitions and notations --- p.12 / Chapter 2.3 --- An algorithm to derive Lmin --- p.13 / Chapter 2.4 --- Example illustrations --- p.17 / Chapter 2.5 --- "The number of fiber links required over the number of nodes of a network, L/N" --- p.21 / Chapter 2.6 --- Summary --- p.22 / Chapter Chapter 3 --- The Consolidation of Two Coexisting Networks with Two Interconnection Links --- p.23 / Chapter 3.1 --- Assumptions --- p.24 / Chapter 3.2 --- Analysis on the optimal location of the two interconnection links --- p.25 / Chapter 3.3 --- Notations --- p.25 / Chapter 3.4 --- Theorems and corollaries --- p.25 / Chapter 3.5 --- "The number of fiber links required over the number of nodes of a network, L/N" --- p.35 / Chapter 3.6 --- Summary --- p.36 / Chapter Chapter 4 --- Protection of the Consolidated Network --- p.37 / Chapter 4.1 --- Full-interconnection case --- p.38 / Chapter 4.2 --- Two interconnection case --- p.39 / Chapter 4.3 --- Summary --- p.44 / Chapter Chapter 5 --- Summary and Future Works --- p.45 / Chapter 5.1 --- Summary --- p.45 / Chapter 5.2 --- Future works --- p.47 / Bibliography --- p.48 / Appendix ´ؤ List of publications --- p.52

This thesis work researches the theory and application of systems performing omnidirectional, non-direct path optical data communication (ONP systems). Such systems are characterized by 1) the communication involves a local, usually circular area; 2) Obstacles are allowed between a transmitter and the receivers. This is in contrast to the point-to-point and line-of-sight communications performed by almost all existing infrared data communication or transmission systems. The elimination of the point-to-point limitation makes ONP systems suitable for optical local area networking. The feasibility of ONP systems employing infrared LEDs and silicon photo detectors has been analyzed and the performance of such systems predicted. The analysis shows that indoor ONP systems are both feasible and practical. Only a few LEDs are required to cover the entire area of a large room. Efforts have been made in finding rules for optimal design of the ONP systems. A set of design criteria and curves have been established. The theoretical analysis has been verified in a successful experiment done with OptoNet, an ONP infrared datalink for local area networks. This experimental system consists of two identical communication units employing FSK modulation and microprocessor controllers. The experiment has demonstrated that the ONP optical data communications can be realized by relatively simple electronic hardware. / Graduation date: 1991

Thesis (M.S. in Information Systems)--Naval Postgraduate School, September 1990. / Thesis Advisor(s): Tung Xuan Bui. Second Reader: Smith, Henry H. "September 1990." Description based on title screen as viewed on December 16, 2009. DTIC Identifier(s): Local area networks, security, control systems, thesis. Author(s) subject terms: Computer security, local area network (LAN), security and control. Includes bibliographical references (p. 87-90). Also available in print.

Project report (M. Eng.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaf 97). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 87-88). Also available via the Internet.

Thesis (M.S. in Computer Science)--Naval Postgraduate School, March 2005. / Thesis Advisor(s): Thuy D. Nguyen, Cynthia E. Irvine. Includes bibliographical references (p. 53). Also available online.

Thesis (M.S.C.I.T.)--Regis University, Denver, Colo., 2005. / Title from PDF title page (viewed on Dec. 28, 2005). Includes bibliographical references.

This thesis presents the development and implementation of a token bus protocol for a Power Line Local Area Network (PLLAN) which utilizes intra-building power distribution circuit as the physical transmission medium. This medium provides a low cost means for data communications with a high degree of portability. Due to the characteristics of the power line and the prototype modem, the network would be easily saturated with data and would have a high collision probabilities. The IEEE 802.4 token bus standard is modified to fit the PLLAN and to bring its performance up. A comparative performance of the original protocol and the modified version shows that the latter provides an improvement in network throughput of up to 15 percent and a reduction in the network join-ring delay of up to 20 percent for a wide workload range. The performance figures of the modified version in a power line network of three SUN 3/50 workstations¹ transmitting at 9.6 kilo-bit per second is also presented and analyzed. ¹Sun workstation is a trademark of Sun Microsystems. / Science, Faculty of / Computer Science, Department of / Graduate

Wireless local area networks (WLANs) have experienced tremendous growth with the proliferation of IEEE 802.11 devices in past two decades. Wireless operators are embracing WLAN for cellular offloading in every smartphone nowadays [1]. The traffic over WLAN requires significant improvement of both WLAN throughput and efficiency. To increase throughput, multiple-input and multiple-output (MU-MIMO) has been adopted in the new generation of WLAN, such as IEEE 802.11ac. MU-MIMO systems exploit the spatial separation of users to increase the network throughput. In an MU-MIMO system, efficient channel sounding is essential for achieving optimal throughput. We propose a dynamic sounding approach for MU-MIMO systems in WLANs. We analyse and show that the optimal sounding intervals exist for single user transmit beamforming (SU-TxBF) and MU-MIMO for given channel conditions. We design a low-complexity dynamic sounding approach that adjusts the sounding interval adaptively in real-time. Through our collected over-the-air channel measurements, we demonstrate significant throughput improvements using our proposed dynamic sounding algorithm while being compliant with IEEE 802.11ac standard. Subsequently, we investigate the user grouping problem of downlink WLANs with MU-MIMO. Particularly, we focus on the problem of whether SU-TxBF or MU-MIMO should be utilized, and how many and which users should be in a multi-user (MU) group. We formulate this problem for maximizing the system throughput subject to the multi-user air time fairness (MU-ATF) criterion. We show that hypergraphs provide a suitable mathematical model and effective tool for finding the optimal or close to optimal solution. We show that the optimal grouping problem can be solved efficiently for the case where only SU-TxBF and 2-user MU groups are allowed in the system. For the general case, where any number of users can be assigned to groups of different sizes, we develop an efficient graph matching algorithm (GMA) based on graph theory principles with near-optimal performance. We evaluate the proposed algorithm in terms of system throughput using an 802.11ac emulator using collected channel measurements from an indoor environment and simulated channel samples for outdoor scenarios. We show that the approximate solution, GMA, achieves at least 93% of the optimal system throughput in all considered test cases. A complementary technique for MU-MIMO is orthogonal frequency-division multiple access (OFDMA), which will be the key enabler to maximize spectrum utilization in the next generation of WLAN, IEEE 802.11ax. An unsolved problem for 802.11ax is maximizing the number of satisfied users in the OFDMA system while accommodating the different Quality of Service (QoS) levels. We evaluate the possibility of regulating QoS through prioritizing the users in OFDMA-based WLAN. We define a User Priority Scheduling (UPS) criterion that strictly guarantees service requests of the spectrum and time resources for the users with higher priorities before guaranteeing resources to those of lower priority. We develop an optimization framework to maximize the overall number of satisfied users under this strict priority constraint. A mathematical expression for user satisfaction under prioritization constraints (scheduler) is formulated first and then linearized as a mixed integer linear program that can be efficiently solved using known optimization routine. We also propose a low-complexity scheduler having comparable performance to the optimal solution in most scenarios. Simulation results show that the proposed resource allocation strategy guarantees efficient resource allocation with the user priority constraints in a dense wireless environment. In particular, we show by system simulation that the proposed low-complexity scheduler is an efficient solution in terms of (1) total throughput and network satisfaction rate (less than 10% from the upper bound), and (2) algorithm complexity (within the same magnitude order of conventional scheduling strategy. / Ph. D.