Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 175-177).

Amateur Packet Radio Networking presently uses the NET/ROM protocol to establish the network. NET/ROM is considered to be insufficient to support the expected growth of the network. This research work proposes to use the TCP/IP protocol suite instead to build the network. A comparison between features of both protocols supports this proposal. A new and simple hardware platform is introduced. This will provide adequate support for initial experiments. Design considerations for both hardware architecture and software architecture are discussed in detail. Implementation of the IP protocol used for routing is discussed. / Graduation date: 1992

University of Macau / Faculty of Social Sciences and Humanities / Department of English

The explosive growth of the Internet during the last few years, has been propelled by the TCP/IP protocol suite and the best effort packet forwarding service. However, quality of service (QoS) is far from being a reality especially for multimedia services like video streaming and video conferencing. In the case of wireless and mobile networks, the problem becomes even worse due to the physics of the medium, resulting into further deterioration of the system performance. Goal of this dissertation is the systematic development of comprehensive models that jointly characterize the performance of transport protocols and media delivery in heterogeneous wireless networks. At the core of our novel methodology, is the use of analytical models for driving the design of media transport algorithms, so that the delivery of conversational and non-interactive multimedia data is enhanced in terms of throughput, delay, and jitter. More speciffically, we develop analytical models that characterize the throughput and goodput of the transmission control protocol (TCP) and the transmission friendly rate control (TFRC) protocol, when CBR and VBR multimedia workloads are considered. Subsequently, we enhance the transport protocol models with new parameters that capture the playback buffer performance and the expected video distortion at the receiver. In this way a complete end-to-end model for media streaming is obtained. This model is used as a basis for a new algorithm for rate-distortion optimized mode selection in video streaming appli- cations. As a next step, we extend the developed models for the aforementioned protocols, so that heterogeneous wireless networks can be accommodated. Subsequently, new algorithms are proposed in order to enhance the developed media streaming algorithms when heterogeneous wireless networks are also included. Finally, the aforementioned models and algorithms are extended for the case of concurrent multipath media transport over several hybrid wired/wireless links.

An architectural framework is proposed to secure the data link layer (Layer 2) in Internet protocol (IP) over Ethernet networks. In this architecture, a new security inter-layering concept, incorporating cryptographic Layer 2 identities, is introduced. Instead of traditional media access control (MAC) addresses, secure and flexible data link layer identifiers are utilized to securely bind Layer 2 and upper layers. In addition, to create security parameters and negotiate identifiers at the data link layer, a key establishment protocol is presented. Moreover, this architecture incorporates the IEEE 802.1AE standard (MACsec) and uses a key hierarchy similar to the IEEE 802.11i standard for future compatibility of wired and wireless networks. Finally, we provide a security analysis of the new data link layer security architecture.

Underwater sensor networks find applications in oceanographic data collection, pollution monitoring, offshore exploration, disaster prevention, assisted navigation, tactical surveillance, and mine reconnaissance. The enabling technology for these applications is acoustic wireless networking. UnderWater Acoustic Sensor Networks (UW-ASNs) consist of sensors and Autonomous Underwater Vehicles (AUVs) deployed to perform collaborative monitoring tasks. The objective of this research is to explore fundamental key aspects of underwater acoustic communications, propose communication architectures for UW-ASNs, and develop efficient sensor communication protocols tailored for the underwater environment. Specifically, different deployment strategies for UW-ASNs are studied, and statistical deployment analysis for different architectures is provided. Moreover, a model characterizing the underwater acoustic channel utilization efficiency is introduced. The model allows setting the optimal packet size for underwater communications. Two distributed routing algorithms are proposed for delay-insensitive and delay-sensitive applications. The proposed routing solutions allow each node to select its next hop, with the objective of minimizing the energy consumption taking the different application requirements into account. In addition, a resilient routing solution to guarantee survivability of the network to node and link failures in long-term monitoring missions is developed. Moreover, a distributed Medium Access Control (MAC) protocol for UW-ASNs is proposed. It is a transmitter-based code division multiple access scheme that incorporates a novel closed-loop distributed algorithm to set the optimal transmit power and code length. It aims at achieving high network throughput, low channel access delay, and low energy consumption. Finally, an efficient cross-layer communication solution tailored for multimedia traffic (i.e., video and audio streams, still images, and scalar sensor data) is introduced.

With the dramatic expansion of computers and communication networks, computer crimes, such as threatening letters, fraud, and theft of intellectual property have been growing at a dreadful rate. The increasing frequency of malicious computer attacks on government agencies and Internet businesses has caused severe economic waste and unique social threats. The problems of protecting data and information on computers and communication networks has become even more critical and challenging, since the widespread adoption of the Internet and the Web. Consequently, it is very urgent to design an integrated network-security architecture so as to make information safer, proactively or reactively defeat any network attack, make attackers accountable, and help the law enforcement system to collect the forensic evidences. Among a variety of attacks on computer servers or communication networks, a prevalent, famous, and serious network-security subject is known as "Denial of Service" (DoS) or "Distributed Denial of Service" (DDoS) attacks. According to an investigation on computer crime conducted by CSI/FBI in 2003, Internet DoS/DDoS have increased in frequency, severity, and sophistication, and have caught international attentions to the vulnerability of the Internet. DoS/DDoS attacks consume the resources of a remote host or network, thereby denying or degrading service to legitimate users. Such attacks are among the hardest security problems to address because they are simple to implement, difficult to prevent, and very difficult to trace. Therefore, this dissertation will firstly concentrate on how to resolve these troublesome DoS/DDoS problems. This is considered as the first step to overcome generic network security problems, and to achieve the final goal for accomplishing a total solution of network security. Instead of tolerating DoS/DDoS attacks by mitigating their effect, to trace back the attacking source for eliminating the attacker is an aggressive and better approach. However, it is difficult to find out the true attacking origin by utilizing the incorrect source IP address faked by the attacker. Accordingly, this dissertation will aim at conquering this representative network security problem, i.e. DoS/DDoS attacks, with IP traceback, and designing an optimal IP traceback. IP traceback ¡X the ability to trace IP packets to their origins¡Xis a significant step toward identifying, and thus stopping, attackers. A promising solution to the IP traceback is probabilistic packet marking (PPM). This traceback approach can be applied during or after an attack, and it does not require any additional network traffic, router storage, or packet size increase. Therefore, the IP traceback research on countering DoS/DDoS attacks will be based on PPM scheme. In this dissertation, three outstanding improvements among four PPM criteria¡Xthe convergency, the computational overhead, and the incomplete PPM deployment problem¡Xhas been achieved. PPM-NPC is proposed to improve the PPM convergency and computational overhead. With non-preemptively compensation, the probability of each marked packet arrived at the victim equals its original marking probability. Therefore, PPM-NPC will efficiently achieve the optimal convergent situation by simply utilizing a 2-byte integer counter. Another better scheme, CPPM, is also proposed, such that the marked packets can be fully compensated as well while they are remarked. With CPPM, the probability of each marked packet arrived at the victim will also equal its original marking probability. Consequently, CPPM will achieve the optimal convergent situation efficiently as well. Furthermore, RPPM-NPC is presented to advance the accuracy of a reconstructed path in an incomplete PPM deployment environment by correcting and recovering any discontinuous individual transparent router and any segment of consecutive double transparent routers. This scheme may also reduce the deployment overhead without requiring the participation of all routers on the attack path. Except for these improved criteria, PPM robustness, some weak assumptions in PPM, and a few unsolved problems for PPM, e.g. reflective DDoS attacks, will also be improved in the future. It is also interesting in combining other network security researches, such as IDS, system access control mechanism, etc., for constructing a more complete network security architecture. Therefore, this research hereby is done in order to completely resolve the troublesome flood-style DoS/DDoS problems, and as the basis for accomplishing a total solution of network security.

Visual analytics, defined as "the science of analytical reasoning facilitated by interactive visual interfaces," emerged several years ago as a new research field. While it has seen rapid growth for its first five years of existence, the main focus of visual analytics research has been on developing new techniques and systems rather than identifying how people conduct analysis and how visual analytics tools can help the process and the product of sensemaking. The intelligence analysis community in particular has not been fully examined in visual analytics research even though intelligence analysts are one of the major target users for which visual analytics systems are built. The lack of understanding about how analysts work and how they can benefit from visual analytics systems has created a gap between tools being developed and real world practices. This dissertation is motivated by the observation that existing models of sensemaking/intelligence analysis do not adequately characterize the analysis process and that many visual analytics tools do not truly meet user needs and are not being used effectively by intelligence analysts. I argue that visual analytics research needs to adopt successful HCI practices to better support user tasks and add utility to current work practices. As the first step, my research aims (1) to understand work processes and practices of intelligence analysts and (2) to evaluate a visual analytics system in order to identify where and how visual analytics tools can assist. By characterizing the analysis process and identifying leverage points for future visual analytics tools through empirical studies, I suggest a set of design guidelines and implications that can be used for both designing and evaluating future visual analytics systems.

This thesis, presents a multiprocessor topology, the hierarchical network of hyper-cubes, which has a low diameter, low degree of connectivity and yet exhibits hypercube like versatile characteristics. The hierarchical network of hyper-cubes consists of k-cubes interconnected in two or more hierarchical levels. The network has a hierarchical, expansive, recursive structure with a constant pre-defined building block. The basic building block of the hierarchical network of hyper-cubes comprises of a k-cube of processor elements and a network controller. The hierarchical network of hyper-cubes retains the positive features of the k-cube at different levels of hierarchy and has been found to perform better than the binary hypercube in executing a variety of application problems. The ASCEND/DESCEND class of algorithms can be executed in O(log2 N) parallel steps (N is the number of data elements) on a hierarchical network of hypercubes with N processor elements. A description of the topology of the hierarchical network of hypercubes is presented and its architectural potential in terms of fault-tolerant message routing, executing a class of highly parallel algorithms, and in simulating artificial neural networks is analyzed. Further, the proposed topology is found to be very efficient in executing multinode broadcast and total exchange algorithms. We subsequently, propose an improvisation of the network to counter faults, and explore implementation of artificial neural networks to demonstrate efficient implementation of application problems on the network. The fault-tolerant capabilities of the hierarchical network of hypercubes with two network controllers per k-cube of processor elements are comparable to those of the hypercube and the folded hypercube. We also discuss various issues related to the suitability of multiprocessor architectures for simulating neural networks. Performance analysis of ring, hypercube, mesh and hierarchical network of hypercubes for simulating artificial neural networks is presented. Our studies reveal that the performance of the hierarchical network of hypercubes is better than those of ring, mesh, hypernet and hypercube topologies in implementing artificial neural networks. Design and implementation aspects of hierarchical network of hypercubes based on two schemes, viz., dual-ported RAM communication, and transputers are also presented. Results of simulation studies for robotic applications using neural network paradigms on the transputer-based hierarchical network of hypercubes reveal that the proposed network can produce fast response times of the order of hundred microseconds.

Thesis (M.S.)--University of Delaware, 2009. / Principal faculty advisor: Charles G. Boncelet, Dept. of Computer & Information Sciences. Includes bibliographical references.