Thesis (M.S.)--University of Toledo, 2009. / Typescript. "Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Engineering." "A thesis entitled"--at head of title. Bibliography: leaves 80-84.

Thesis (M.S.)--Villanova University, 2009. / Computer Science Dept. Includes bibliographical references.

Thesis (Ph. D.)--Washington State University, August 2007. / Includes bibliographical references (p. 94-100).

Dissertation (Ph.D.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (p.175-183).

Thesis (Ph. D.)--Auburn University. / Abstract. Includes bibliographical references (p. 151-160).

However, applying directional antennas to wireless networks can also cause new collisions, such as the new hidden terminal problem and the deafness problem. We study the challenges in the MAC layer design with directional antennas and present the state of the art of current MAC protocols with directional antennas. Then, we propose a novel collision avoidance scheme in terms of BT-DMAC (Busy-Tone based Directional Medium Access Control) to address the new collisions with directional antennas. Both the analytical and simulation results show that transmitting busy tones on a different channel can effectively reduce the hidden nodes and mitigate the deafness problem. Thus, integrating multiple channels with directional antennas can bring numerous benefits. Furthermore, we also explore some techniques in the MAC layer design with directional antennas. Some useful insights are also given. / The capacity of wireless networks are mainly affected by two key factors: the interference among concurrent transmissions and the number of simultaneous transmissions on a single interface. Recent studies have found that, using multiple channels can separate concurrent transmissions and significantly improve network throughput. However, those studies only consider wireless nodes that are only equipped with omni-directional antennas, which cause high collisions. On the other hand, some researchers have found that directional antennas bring more benefits such as the reduced interference and the increased spatial reuse compared with omni-directional antennas. But, they only focused on a single-channel network which only allows finite concurrent transmissions. In this thesis, we propose a novel network architecture, in terms of multi-channel networks using multiple directional antennas ( MC-MDA), which integrates the two technologies of multiple channels and directional antennas together and potentially brings more benefits. / We study the capacity of MC-MDA networks and explore the benefits of such networks. We have found that using directional antennas in multi-channel networks can greatly increase the network capacity. Furthermore, such networks require fewer channels than multi-channels with omni-directional antennas. More specifically, we study the channel assignment problem of such MC-MDA networks. Our results indicate that using directional antennas in wireless networks can significantly reduce the required number of channels. Directional antennas have a better spectrum reuse than omni-directional antennas. / Dai, Hongning. / Adviser: Kam-Wing Ng. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3596. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 173-183). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Due to the broadcast nature of wireless medium, simultaneous transmissions interfere with each other (especially transmissions on nearby links), thus adversely affecting data rates and Quality of Service (QoS) in the system. Interference mitigation is therefore a fundamental issue that must be addressed in next generation wireless networks. An important technique for this is to control the links' transmission power. Driven by the wide spread of broadband wireless data services, a system-wide efficiency metric (i.e., system utility) is typically used to characterize the advantage of power control. / In interference-limited wireless networks where simultaneous transmissions on nearby links heavily interfere with each other, however, power control alone is not sufficient to eliminate strong levels of interference between close-by links. In this case, scheduling, which allows close-by links to take turns to be active, plays a crucial role for achieving high system performance. Joint power control and scheduling that maximizes the system utility has long been a challenging problem. The complicated coupling between the signal-to-interference ratio of concurrently active links as well as the flexibility to vary power allocation over time gives rise to a series of non-convex optimization problems, for which the global optimal solution is hard to obtain. The second goal of this thesis is to solve the non-convex joint power control and scheduling problems efficiently in a global optimal manner. In particular, it is the monotonicity rather than the convexity of the problem that we exploit to devise an efficient algorithm, referred to as S-MAPEL, to obtain the global optimal solution. To further reduce the complexity, we propose an accelerated algorithm, referred to as A-S-MAPEL, based on the inherent symmetry of the optimal solution. The optimal joint-power-control-and-scheduling solution obtained by the proposed algorithms serves as a useful benchmark for evaluating other existing schemes. With the help of this benchmark, we find that on-off scheduling is of much practical value in terms of system utility maximization if "off-the-shelf' wireless devices are to be used. / Maximizing a system-wide utility through power control is an NP-hard problem in general due to the complicated coupling interference between links. Thus, it is difficult to solve despite its paramount importance. The first goal of this thesis is to find global optimal power allocations to a variety of system utility maximization (SUM) problems based on the recent advances in monotonic optimization. Instead of tackling the non-convexity issue head on, we bypass non-convexity by exploiting the monotonic nature of the power control problem. In particular, we establish a monotonic optimization framework to maximize a system utility through power control in single-carrier or multi-carrier wireless networks. Furthermore, MAPEL and M-MAPEL are respectively proposed to obtain the global optimal power allocation efficiently in single-carrier or multi-carrier wireless networks. The main benefit of MAPEL and M-MAPEL is to provide an important benchmark for performance evaluation of other heuristic algorithms targeting the same problem. With the help of MAPEL or M-MAPEL, we evaluate the performance of several existing algorithms through extensive simulations. On the other hand, by tuning the approximation factor in MAPEL and M-MAPEL, we could engineer a desirable tradeoff between optimality and convergence time. / With the proliferation of wireless infrastructureless networks such as ad hoc and sensor networks, it is increasingly crucial to devise an algorithm that solves the power control problem in a distributed fashion. In general, distributed power control is more complicated due to the lack of centralized infrastructure. As the third goal of this thesis, we consider a distributed power control algorithm for infrastructureless ad hoc wireless networks, where each link distributively and asynchronously updates its transmission power with limited message passing among links. This algorithm provably converges to the optimal strategy that picks global optimal solutions with probability 1 despite the non-convexity of the power control problem. In contrast with existing distributed power control algorithms, our algorithm makes no stringent assumptions on the system utility functions. In particular, the utility function is allowed to be concave or non-concave, differentiable or non-differentiable, continuous or discontinuous, and monotonic or non-monotonic. / Qian, Liping. / Adviser: Yingjun (Angela) Zhang. / Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 133-139). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Computing consistent global states in a distributed system is a fundamental problem. A large class of distributed system problems can be cast as construction of consistent global states and evaluation of relevant properties over these global states. Examples of such problems include the monitoring and debugging of distributed systems, the detection of stable properties such as deadlock, termination, and loss of tokens, protocol specification and verification, garbage collection, checkpointing and failure recovery, and many others. / Finally, we will present a suit of three new snapshot algorithms for mobile ad hoc network systems: cooperative, localized, and centralized. These new snapshot algorithms have different timing and tailoring components, Compared to existing snapshot algorithms, our snapshot algorithms can be proven to work in the presence of node mobility and dynamic topology changes, i.e., all of them can compute consistent global states in a mobile ad hoc network system. We will also evaluate the effectiveness and efficiency of these newly proposed snapshot algorithms by using extensive simulations. / Firstly, we will develop a system model for a mobile ad hoc network system. In addition to the internal, send and receive events that are considered in a traditional system model for static systems, two novel types of events called on and off are introduced to represent dynamic topology changes in our system model. Based on these on and off events, it is convenient to devise new distributed algorithms that can handle dynamic topology changes for the mobile ad hoc network environment. We will also propose a new relation called the extended-happened-before relation, which is generalized from the well-known happened-before relation defined by Lamport, to fully model the ordering of events in a mobile ad hoc network system. The event orders captured by the extended-happened-before relation playa critical role in solving the snapshot problem at hand. / However, consistent global states are not freely available in distributed systems without shared memory and synchronized clocks. In the literature, the fundamental problem of constructing consistent global states in a distributed system was defined as the snapshot problem. Although many solutions to the snapshot problem have been developed for various types of distributed systems, most of them cannot be applied directly to a mobile ad hoc network system, which has no fixed network infrastructure for operating support and may experience dynamic topology changes due to node mobility. In this thesis, we present a systematic study on the snapshot problem in mobile ad hoc network systems. / Secondly, we will derive a new consistency criterion for constructing a global state in a mobile ad hoc network system. Without a common time base and shared memory, the development of the new consistency criterion sticks to the fundamental principle that if the events for recording the local states are ensured to be concurrent, then the recorded local states are equivalent to those that are recorded simultaneously in real time and the resulting global state is guaranteed to be consistent. Importantly, we will also show a consistency theorem, which gives a necessary and sufficient condition for computing consistent global states in a mobile ad hoc network system. That is, a global state of a mobile ad hoc network system is consistent if and only if its corresponding cut is not only causally consistent but also topologically consistent. / Thirdly, we will propose a simple method called timing-and-tailoring to design and analyze snapshot algorithms in a well structured approach. In this generic method, a snapshot algorithm is decomposed into two basic components. The first component called timing is used to record the ordering of events by using logical time algorithms. The second component called tailoring is used to find a consistent global state based on known event ordering. To demonstrate the proposed timing-and-tailoring method, we will also present several examples of using this method to design and analyze snapshot algorithms. These examples provide helpful insights in designing new snapshot algorithms for mobile ad hoc network systems. / Wu, Dan. / Adviser: Man Hon Wong. / Source: Dissertation Abstracts International, Volume: 73-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 135-145). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Lam, Kim Yung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 87-92). / Abstract also in Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Rayleigh Fading Channels --- p.1 / Chapter 1.2 --- Wireless Ad Hoc Networks --- p.3 / Chapter 1.3 --- Ad Hoc Routing Protocols --- p.3 / Chapter 1.4 --- Information Capacity --- p.4 / Chapter 1.5 --- Cooperative Communications --- p.6 / Chapter 1.6 --- Outline of Thesis --- p.7 / Chapter 2 --- Background and Related Work --- p.8 / Chapter 2.1 --- Cooperative Communications --- p.8 / Chapter 2.1.1 --- Cooperative Diversity --- p.8 / Chapter 2.1.2 --- User Cooperation --- p.10 / Chapter 2.1.3 --- Coded Cooperation --- p.11 / Chapter 2.2 --- Cooperative Routing --- p.12 / Chapter 2.3 --- Information-Theoretic Study --- p.16 / Chapter 2.4 --- Optimization techniques --- p.17 / Chapter 3 --- Single-Source Single-Destination Cooperative Routing --- p.21 / Chapter 3.1 --- System Model --- p.22 / Chapter 3.1.1 --- Network Assumptions --- p.22 / Chapter 3.1.2 --- Routing Process --- p.22 / Chapter 3.1.3 --- Transmitting Signal --- p.23 / Chapter 3.1.4 --- Link Cost Formulation --- p.23 / Chapter 3.2 --- Minimum Energy Cooperative Route --- p.25 / Chapter 3.2.1 --- Cooperative Graph --- p.25 / Chapter 3.2.2 --- An Example of the Cooperative Graph --- p.27 / Chapter 3.2.3 --- Non-reducible property of the Cooperative Graph --- p.29 / Chapter 3.3 --- Optimized Scheduling --- p.32 / Chapter 3.3.1 --- KKT conditions --- p.32 / Chapter 3.3.2 --- Newton´ةs Method --- p.34 / Chapter 3.4 --- Complexity Analysis --- p.35 / Chapter 3.5 --- Simplified Scheduling Process --- p.37 / Chapter 3.5.1 --- Linear relationship in low rate regime --- p.37 / Chapter 3.5.2 --- The Simplified Scheduling Algorithm --- p.39 / Chapter 4 --- Heuristic Single-Source Cooperative Routing Schemes --- p.41 / Chapter 4.1 --- Maximum Hops Cut --- p.42 / Chapter 4.1.1 --- The Routing Protocol --- p.42 / Chapter 4.1.2 --- Simulations --- p.46 / Chapter 4.2 --- Maximum Relays Subgraph --- p.47 / Chapter 4.2.1 --- The Routing Protocol --- p.47 / Chapter 4.2.2 --- Simulations --- p.51 / Chapter 4.3 --- Adaptive Maximum Relays Subgraph --- p.55 / Chapter 4.3.1 --- The Routing Protocol --- p.55 / Chapter 4.3.2 --- Simulations --- p.57 / Chapter 4.4 --- Comparison of three protocols --- p.60 / Chapter 4.4.1 --- Implementation --- p.60 / Chapter 4.4.2 --- Cooperative Performance --- p.60 / Chapter 4.5 --- Enhancement of the algorithms --- p.61 / Chapter 4.5.1 --- Conclusion --- p.63 / Chapter 5 --- Multiplexing Cooperative Routes in Multi-source Networks --- p.64 / Chapter 5.1 --- Problem Formation --- p.65 / Chapter 5.1.1 --- The Network Model --- p.65 / Chapter 5.1.2 --- Objective Aim --- p.65 / Chapter 5.1.3 --- Link Cost Formulation --- p.66 / Chapter 5.1.4 --- Time Sharing and Interference --- p.66 / Chapter 5.1.5 --- Multiple Sources Consideration --- p.67 / Chapter 5.2 --- Multi-Source Route-Multiplexing Protocols --- p.68 / Chapter 5.2.1 --- Full Combination with Interference (FCI) --- p.68 / Chapter 5.2.2 --- Full Combination with Time Sharing (FCTS) --- p.68 / Chapter 5.2.3 --- Selection Between Interference and Time Sharing (SBITS) --- p.69 / Chapter 5.2.4 --- Interference and time sharing combinations --- p.71 / Chapter 5.2.5 --- The Simplified Version for SBITS --- p.72 / Chapter 5.3 --- Stage Cost Calculation --- p.73 / Chapter 5.3.1 --- Total stage cost formation in the sub timeslot --- p.73 / Chapter 5.3.2 --- Total stage cost formulation in different routing protocols --- p.74 / Chapter 5.3.3 --- Multiplexing for non-uniform timeslot routes --- p.75 / Chapter 5.4 --- Simulation --- p.76 / Chapter 5.4.1 --- Simulation model --- p.76 / Chapter 5.4.2 --- Simulation detail --- p.77 / Chapter 5.4.3 --- Simulation evaluation --- p.78 / Chapter 6 --- Conclusion and Future Work --- p.83 / Chapter 6.1 --- Conclusion --- p.83 / Chapter 6.2 --- Future Work --- p.84 / Chapter 6.2.1 --- Multiple-Source System Optimal Route --- p.84 / Chapter 6.2.2 --- Better Relay-Selection Policy --- p.85 / Chapter 6.2.3 --- Single Optimization for Minimum Energy Cooperative Route --- p.85 / Chapter 6.2.4 --- Dynamic Programming for Minimum Energy Cooperative Route --- p.85 / Chapter 6.2.5 --- Min-Max Problem --- p.85 / Chapter 6.2.6 --- Distributed Algorithm --- p.86 / Chapter 6.2.7 --- Game Theory --- p.86 / Bibliography --- p.87

Ruan, Sichao. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 62-65). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Multihop Ad Hoc Wireless Networks --- p.1 / Chapter 1.1.1 --- Introduction to Multihop Ad Hoc Networks --- p.2 / Chapter 1.1.2 --- Scalability of Ad Hoc Wireless Networks --- p.3 / Chapter 1.2 --- Hidden Terminal Problem --- p.3 / Chapter 1.3 --- Exposed Terminal Problem --- p.5 / Chapter 1.4 --- Overview of the Thesis --- p.6 / Chapter 2 --- Background --- p.8 / Chapter 2.1 --- MAC Protocols for Wireless Networks --- p.8 / Chapter 2.1.1 --- Aloha --- p.8 / Chapter 2.1.2 --- CSMA/CA --- p.9 / Chapter 2.1.3 --- IEEE 802.11 DCF Standard --- p.10 / Chapter 2.2 --- Related Work --- p.12 / Chapter 2.2.1 --- Schemes for Hidden Node Problem --- p.12 / Chapter 2.2.2 --- Schemes for Exposed Node Problem --- p.13 / Chapter 2.3 --- Tradeoff between Hidden and Exposed Nodes --- p.14 / Chapter 2.4 --- The Effect of Carrier Sensing Range --- p.17 / Chapter 3 --- Analysis on Carrier Sensing Range --- p.18 / Chapter 3.1 --- Analysis Model --- p.18 / Chapter 3.1.1 --- Terminal Configurations --- p.18 / Chapter 3.1.2 --- Timing/Packet Parameters --- p.19 / Chapter 3.1.3 --- Protocol Approximation --- p.20 / Chapter 3.1.4 --- Throughput Measurement --- p.21 / Chapter 3.2 --- Derivation of Throughput --- p.21 / Chapter 3.2.1 --- Channel Modeling --- p.22 / Chapter 3.2.2 --- Actual Transmission Rate --- p.24 / Chapter 3.2.3 --- Case One --- p.24 / Chapter 3.2.4 --- Case Two --- p.26 / Chapter 3.2.5 --- Mathematical Form of Throughput --- p.28 / Chapter 3.2.6 --- Analysis Results --- p.30 / Chapter 3.3 --- Implications --- p.31 / Chapter 3.3.1 --- Value of Sensing Range in CSMA/CA --- p.31 / Chapter 3.3.2 --- Need for New MAC Protocols --- p.32 / Chapter 4 --- MAC Protocols by Congestion Control --- p.34 / Chapter 4.1 --- Motivations and Principles --- p.34 / Chapter 4.1.1 --- Balancing Hidden and Exposed Nodes --- p.35 / Chapter 4.1.2 --- Controlling Carrier Sensing Range --- p.36 / Chapter 4.1.3 --- Non-homogenous Sensing Range --- p.36 / Chapter 4.2 --- Algorithm Descriptions --- p.38 / Chapter 4.2.1 --- Core Concept --- p.38 / Chapter 4.2.2 --- LDMI Control Scheme --- p.40 / Chapter 4.2.3 --- Tahoe Control Scheme --- p.41 / Chapter 5 --- Simulation Analysis --- p.44 / Chapter 5.1 --- Simulation Configurations --- p.44 / Chapter 5.1.1 --- Geometric Burst Traffic Model --- p.45 / Chapter 5.1.2 --- Network Topology --- p.46 / Chapter 5.1.3 --- Simulation Parameters --- p.47 / Chapter 5.2 --- Throughput Comparisons --- p.48 / Chapter 5.3 --- Fairness Comparisons --- p.50 / Chapter 5.3.1 --- Situation of Unfairness --- p.50 / Chapter 5.3.2 --- Fairness Measurement --- p.52 / Chapter 5.4 --- Convergence Comparisons --- p.54 / Chapter 5.5 --- Summary of Performance Comparison --- p.55 / Chapter 6 --- Conclusions --- p.56 / Chapter A --- Categories of CSMA/CA --- p.58 / Chapter A.1 --- 1-persistent CSMA/CA --- p.58 / Chapter A.2 --- non-persistent CSMA/CA --- p.58 / Chapter A.3 --- p-persistent CSMA/CA --- p.59 / Chapter B --- Backoff Schemes --- p.60 / Chapter B.1 --- Constant Window Backoff Scheme --- p.60 / Chapter B.2 --- Geometric Backoff Scheme --- p.60 / Chapter B.3 --- Binary Exponential Backoff Scheme --- p.61 / Bibliography --- p.62