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Afifi, Mohammed Ahmed Melegy MohammedTCP FTAT (Fast Transmit Adaptive Transmission): A New End-To- End Congestion Control Algorithm
Master of Science in Electrical Engineering, Cleveland State University, 2014, Washkewicz College of Engineering
Congestion Control in TCP is the algorithm that controls allocation of network resources for a number of competing users sharing a network. The nature of computer networks, which can be described from the TCP protocol perspective as unknown resources for unknown traffic of users, means that the functionality of the congestion control algorithm in TCP requires explicit feedback from the network on which it operates. Unfortunately this is not the way it works with TCP, as one of the fundamental principles of the TCP protocol is to be end-to-end, in order to be able to operate on any network, which can consist of hundreds of routers and hundreds of links with varying bandwidth and capacities. This fact requires the Congestion Control algorithm to be adaptive by nature, to adapt to the network environment under any given circumstances and to obtain the required feedback implicitly through observation and measurements. In this thesis we propose a new TCP end-to-end congestion control algorithm that provides performance improvements over existing TCP congestion control algorithms in computer networks in general, and an even greater improvement in wireless and/or high bandwidth- delay product networks.

Committee:

Nigamanth Sridhar, PhD (Committee Chair); Chansu Yu, PhD (Committee Member); Pong Chu, PhD (Committee Member)

Subjects:

Computer Engineering; Computer Science; Electrical Engineering

Keywords:

TCP; Congestion Control; Computer Networks; TCP NewReno; TCP Westwood; TCP Cubic; Linux TCP; ns-3; DCE Cradle; Direct Code Execution Cradle - ns-3; high bandwidth delay product networks; random loss radio signal; Adaptive Transmission

Shukla, ManishTCP Performance With Multipath Routing in Wireless Ad Hoc Networks
MS, University of Cincinnati, 2003, Engineering : Computer Science
Majority of applications on the Internet today use TCP for reliable communication. TCP has been designed for and fine tuned to wired environments, but recent studies have shown that its performance suffers in wireless network environments, particularly in ad hoc networks because of the presence of multiple wireless hops. Routing has been the most focused area of research in recent years in wireless ad hoc networking area. Many on-demand routing protocols have been proposed to improve robustness in the face of link and route failures and facilitate packet transmission. Using multiple paths to route packets is one of them. We examine the performance of the TCP protocol with multiple paths in mobile ad hoc networks (MANETs). We set up multiple routes between the TCP source and destination either manually or using an on-demand multipath routing protocol, and forward packets on both paths to reduce the load on one single path. Ordinarily one would expect the multiple paths to reduce conflict between TCP data and acknowledgement packets thus giving better overall performance. Our results do incidate that TCP performance with multipath routing shows some improvement for long routes; however, shorter routes may experience slight degradation in performance as compared to single path routing. This observation remains true even when contention-based scheduling is used to schedule packets on different paths, or the multiple routes are chosen such that they have a minimum radio interference among themselves. We conclude that the TCP could gain only limited benefits with multipath routing.

Committee:

Dr. Samir R. Das (Advisor)

Keywords:

TCP over wireless; TCP over AD HOC Networks; multipath routing; TCP performance with multipath; multipath in wireless network

Narasimhan, PriyaAn Evaluation of Realistic TCP Traffic on Satellite Networks
Master of Science (MS), Ohio University, 2002, Electrical Engineering & Computer Science (Engineering and Technology)

There are many factors governing the performance of TCP-based applications on satellite channels. The end-to-end performance of TCP is known to be degraded by the delay, noise and asymmetry inherent in geosynchronous systems. These results have been based on experiments that evaluate the performance of TCP in single flow tests. Single flow tests are useful for deriving information on the theoretical behavior of TCP and allow for easy diagnosis of problems. However, they do not represent realistic situations and therefore cannot be used to authoritatively comment on performance issues. Our experiments tested TCP's performance in a more dynamic environment with competing traffic flows from hundreds of TCP connections running simultaneously across the satellite channel.

Another aspect investigated was TCP reaction to bit errors on satellite channels. TCP interprets delays and losses as a sign of network congestion. This causes it to cut down its transmission rate leading to poor performance. We allowed the bit error rate on our satellite channel to vary widely and tested the performance of TCP as function of these bit error rates. Our studies show that the average performance of TCP on satellite channels in these realistic conditions is good and establishes the robustness of TCP on satellite channels. Many of our observations contradict commonly held beliefs about the performance of TCP on satellite links.

Committee:

Shawn Ostermann (Advisor)

Keywords:

TCP Performance; Satellite Channels; Performance Degradation; Realistic TCP Traffic

Cushman, Christopher ScottDestruction of chlorinated hydrocarbons by zero-valent zinc and bimetallic zinc reductants in bench-scale investigations
Master of Science (MS), Wright State University, 2014, Earth and Environmental Sciences
Many remediation technologies have been developed to treat extensive subsurface contamination by chlorinated hydrocarbons (CHCs). One such technology is a permeable reactive barrier (PRB), which contains reactive media that acts as an electron donor in order to reduce CHCs. Extensive effort has been placed on finding the most suitable reactive media in PRBs, with zero-valent iron (ZVI) being the most commonly utilized media. However, zero-valent zinc (ZVZ) is a promising replacement for ZVI in PRBs as it will more readily donate electrons, resulting in more rapid degradation of CHCs. In addition, amending a secondary/catalytic metal to primary metal surface can result in increased degradation kinetics and yield of dechlorinated byproducts. In this investigation, chlorinated methanes (CF and DCM), ethanes (1,1,2,2-TeCA, 1,1,2-TCA, 1,1,1-TCA, and 1,2-DCA), ethenes (PCE, TCE, cis-DCE, trans-DCE, and VC) and propanes (1,2,3-TCP and 1,2-DCP) were reduced by ZVZ and Zn bimetallic reductants. Results indicated that Cu/Zn was a more potent bimetallic reductant than Pd/Zn and Ni/Zn due to impressive CF degradation kinetics and increased yield of methane formed via direct transformation of CF to methane. Cu/Zn was used in reduction of all other compounds and did not significantly change byproduct distributions when compared to ZVZ. Reductive β-elimination was an important degradation pathway observed for chlorinated ethanes and ethenes, with reduction of chlorinated ethenes via this pathway resulting in the formation of highly reactive chlorinated acetylene intermediates, thus preventing the formation of VC. It appears that ZVI will reduce chlorinated ethenes via reductive β-elimination more readily than Zn reductants, suggesting an advantage of ZVI in the reduction of chlorinated ethenes. However, Zn reductants appear to be well suited for PRB applications at sites contaminated with 1,2,3-TCP, as reduction with Zn reductants yields fully dechlorinated byproducts via a reductive β-elimination to hydrogenolysis sequence, unlike ZVI. Cu/Zn increased degradation kinetics compared to ZVZ for all CHCs investigated, but only slight enhancement in kinetics was observed for chlorinated propanes. Increased chlorinated methane, ethane, and propane kinetics have been reported with ZVZ when compared to ZVI, thus suggesting the need to further study Cu/Zn as a potential replacement for ZVI in PRB applications.

Committee:

Abinash Agrawal, Ph.D. (Advisor); Mark Goltz, Ph.D. (Committee Member); Songlin Cheng, Ph.D. (Committee Member)

Subjects:

Chemistry; Environmental Engineering; Environmental Geology; Environmental Management; Environmental Science; Environmental Studies; Organic Chemistry; Sustainability; Water Resource Management

Keywords:

chlorinated hydrocarbons; zero-valent zinc; ZVZ; zero-valent iron; ZVI; bimetallic; reductants; copper; Cu-Zn; palladium; Pd-Zn; nickel; Ni-Zn; chlorinated methanes; chlorinated ethanes; chlorinated ethenes; chlorinated propanes; 1,2,3-TCP

Iqbal, AsifMonitoring Remote Financial Transaction Control Devices Using SNMP Over TCP
MS, Kent State University, 2009, College of Arts and Sciences / Department of Computer Science
Remote monitoring solutions are prevalent in the financial industry to monitor Financial Transaction Devices (FTD's) such as an Automated Teller Machine (ATM) over highly congested or faulty networks. Fault detection of hardware devices on systems with a diverse software stack is required to be done remotely in a guaranteed delivery mechanism and in a timely fashion. Simple Network Management Protocol (SNMP) has been a standard and is widely used for such applications over UDP for fixed sized and a predefined payload. Such solutions create quality of service (QoS) issues with messages being lost during severe congestion and high network traffic. The message loss can result in, during busy times of the day, an FTD to be down at a remote location for hours during busy times of the day. Due to non-receipt of status message by the remote monitoring application, an FTD may stay down for a much longer period than expected resulting in financial losses. In this thesis, we propose a solution to this problem which is based on SNMP messaging over TCP. Due to the fact that TCP is congestion-sensitive and UDP is not, and MAC layer back-off algorithms exacerbate the delay and loss differently in wired and wireless environment, we conducted a performance analysis of SNMP over several multi-hop wireless and wired networks. We studied the impact of load and number of hops on the performance of SNMP over TCP and UDP using delay, loss and throughput metrics.

Committee:

Dr. Hassan Peyravi, PhD (Advisor); Dr. Paul A. Farrell, PhD (Committee Member); Dr. Javed Khan, PhD (Committee Member)

Subjects:

Computer Science

Keywords:

SNMP; Remote Monitoring; Financial Transaction Control Device; UDP; TCP; QoS; Throughput

Desai, Harit SEvaluation and Tuning of Gigabit Ethernet performance on Clusters
MS, Kent State University, 2007, College of Arts and Sciences / Department of Computer Science
Cluster computing imposes heavy demands on the communication network. Gigabit Ethernet technology can provide the required bandwidth to meet these demands. However, it has also shifted the communication bottleneck from network media to protocol processing. In this thesis, we present an overview of Gigabit Ethernet technology and study the end-to-end Gigabit Ethernet communication bandwidth and latency. Performance graphs are collected using NetPIPE which clearly show the performance characteristics of TCP/IP and VIA over Gigabit Ethernet. Here we discuss the communication performance attainable with a PC cluster connected by a Gigabit Ethernet network. Gigabit Ethernet is the third generation of Ethernet technology and offers raw bandwidth of 1 Gbps. The focus of this work is to discuss the Gigabit Ethernet technology, to evaluate and analyze the end-to-end communication latency and achievable bandwidth, and to monitor the effects of software and hardware components on the overall network performance.

Committee:

Paul Farrell (Advisor)

Subjects:

Computer Science

Keywords:

Gigabit ethernet performance; Cluster computing; TCP/IP performance

Stahr, Michael CDESIGN AND IMPLEMENTATION OF AN EMPLOYEE JOB SCHEDULING AND PROGRESSION TRACKING SYSTEM
Master of Systems Analysis, Miami University, 2002, Systems Analysis
This thesis is a project-oriented one that features the design and development of a software system used for employee hourly progression tracking and job scheduling in an industrial environment. This software was developed at a professional level as verified by its adoption by one of the largest boxboard companies in the industry for its day-to-day operations. Some of the main features of this system are: Specialized ActiveX controls Object oriented design utilizing classes in Visual Basic 6.0 and C++ Stored procedures embedded in Microsoft SQL Server 7.0 TCP/IP technology This system consists of two integrated subsystems, Tracker and Crew Master. The first, Tracker, was designed to replace a manual system used by the accounting department for tracking employee hourly progression. The second, Crew Master, replaces a manual system for scheduling hourly employees for job positions as well as vacation scheduling.

Committee:

Jim Kiper (Advisor)

Keywords:

Visual Basic; SQL Server; ActiveX; TCP; IP; Programming; Stored Procedures; C++; Microsoft; Boxboard; Industry; Software; Object oriented; Scheduling

Kaniganti, Madhuri ChoudaryFEASIBILITY OF NS-2 MODELS IN SIMULATING THE CUSTODY TRANSFER MECHANISM
Master of Science (MS), Ohio University, 2005, Telecommunications (Communication)

The custody transfer mechanism is the main component of the Delay Tolerant Networking (DTN) architecture, where the responsibility of the data transfer to the destination end node from the source node is handled by a custody node. This mechanism is proposed by DTN for the challenged networks with limited bandwidth, large propagation delays and high error rate. The custody-based data transfer mechanism proposed by DTN is modeled using ns-2 in this thesis. The simulation of the custody transfer mechanism is carried out in wired and IEEE 802.11 wireless network environments in ns-2 with TCP as the Transport mechanism. With the existing capability of ns-2, the environments are simulated with limited bandwidth and moderate delays. The end-to-end transfer mechanism with data transfer from the source node to the destination node is also modeled to compare the performance of the transfer mechanisms. The simulated transfer mechanisms in ns-2 show that the custody transfer mechanism works better than end-to-end transfer mechanism in some circumstances, and shows similar performance to end-to-end in other situations studied.

Committee:

Hans Kruse (Advisor)

Subjects:

Information Science

Keywords:

Custody Transfer Mechanism; Ns-2; TCP

Barnard, Michael T.Data Transfer System for Host Computer and FPGA Communication
Master of Science (M.S.), University of Dayton, 2015, Electrical Engineering
This Thesis describes a communication system to allow for the transmission of data between a host computer and a DE2-115 FPGA board over an Ethernet connection. This is achieved by using a socket between the host computer and a NIOS II embedded processor that accepts the data from the host computer and transfers it to the FPGA fabric. The host computer uses a C++ program to open a file and send the data over the socket to the NIOS II processor. The NIOS II acts as memory controller for the Synchronous Dynamic Random Access Memory (SDRAM) on the board with separate input and output data sections for the Hardware Description Language (HDL) processing module. A HDL module then processes the data and sends it back to the NIOS II to be returned to the host computer over the socket. The data transfer system is tested with three basic image processing functions performed on three sample images to verify its functionality. This data transfer system allows for easier testing of digital designs on the DE2-115 board by providing test data to the digital design in an efficient manner.

Committee:

Eric Balster, Ph.D. (Committee Chair); John Weber, Ph.D. (Committee Member); Tarek Taha, Ph.D. (Committee Member)

Subjects:

Electrical Engineering

Keywords:

Data Transfer; FPGA Board; NIOS II Processor; Sockets; Ethernet; TCP IP

Schomp, Kyle GrahamDynamic TCP Proxies: Coping with Mobility and Disadvantaged Hosts in MANETs
Master of Sciences, Case Western Reserve University, 2010, EECS - Computer and Information Sciences

TCP proxies have been introduced as a method to improve throughput and reduce congestion in mobile ad hoc networks. Proxies split the path into several shorter paths which have higher throughput due to reduced packet loss and round trip time. As a side effect, congestion is reduced because fewer link layer retransmissions occur. In current protocols, proxies are assigned at the start of the transfer and must be used for the duration. Due to mobility and congestion change, pinned proxies can actually reduce throughput.

In this thesis, we present a second version of the DTCP protocol which includes the ability to switch proxies in the middle of a transfer. We demonstrate in the Network Simulator version 2 that the new protocol performs better than other related protocols in simulated mobile ad hoc networks with varying levels of mobility and congestion.

Committee:

Shudong Jin, PhD (Committee Chair); Michael Rabinovich, PhD (Advisor); Vincenzo Liberatore, PhD (Committee Member)

Subjects:

Information Systems

Keywords:

mobile ad hoc network;TCP Proxy;

Gao, YuanCongestion Control for Next-Generation Global Internets
Doctor of Philosophy, The Ohio State University, 2002, Electrical Engineering
As the size and application domains of the Internet grow explosively during recent years, several new phenomena have been observed and new research issues have emerged in Internet congestion control. In this dissertation, we address these congestion control issues for next-generation Internets with the focus on both the transport and the IP layers. Specifically, we address the following problems: (I) Congestion control of multicast for continuous media applications with the objectives of (weighted) fairness, TCP-friendliness, and scalability. (II) End-host-based, coordinated congestion control of TCP/UDP traffic to enable connections that traverse the same backbone link toshare congestion information and to coordinate among them all the congestion avoidance/control activities. (III) Exploitation of the correlation structure across multiple time scales (and hence the predictability) of Internet traffic for better AQM scheme and TCP congestion control. (IV) Incorporation of protocol effects ignored by previous TCP models in an enhanced TCP model. Design of an AQM controller to stabilize the queue at a router based on the enhanced model. The dissertation is a combination of two synergistic components: design of algorithms/protocols in an analytical framework and their validation with detailed ns-2 simulation and software system building and experiments in FreeBSD on a network testbed.

Committee:

Jennifer Hou (Advisor)

Keywords:

TCP; Congestion; traffic; packet; queues; packet losses; RACCOOM

THANGARAJ, ARUNAPERFORMANCE ANALYSIS OF PRIORITIZED TCP ACK SCHEMES IN THE IEEE 802.11e WLANs
MS, University of Cincinnati, 2007, Engineering : Computer Engineering
With the advent of multimedia applications over Wireless Local Area Networks (WLANs), the IEEE 802.11e standard was proposed to incorporate Quality of Service (QoS) parameters in the Medium Access Control (MAC) layer. It has been found through previous research work that the throughput of Transmission Control Protocol (TCP) is less when compared to that of User Datagram Protocol (UDP) in the IEEE 802.11e MAC layer protocol. This is because the TCP ACK (Acknowledgement) packets are queued up at the Access Points (APs), as the TCP ACK packets are not prioritized. In this research work, the performance of TCP traffic in the IEEE 802.11e MAC layer protocol is evaluated and two TCP ACK prioritizing schemes are proposed. The proposed schemes improve the overall throughput of TCP in the IEEE 802.11e MAC layer protocol while maintaining the QoS requirements of the IEEE 802.11e MAC layer protocol. We also analyze the problem of starvation of lower priority traffic in the IEEE 802.11e MAC layer protocol and its effects on the performance of lower priority TCP traffic in particular. The proposed second scheme of TCP ACK prioritization aims at improving the throughput of the lower priority TCP traffic in particular under heavy network load while maintaining the QoS requirements of the higher priority traffic. The schemes have been verified through extensive simulation results.

Committee:

Dr. Qing-An Zeng (Advisor)

Keywords:

IEEE 802.11e; TCP ACK; prioritization

Bykova, MarinaStatistical Analysis of Malformed Packets and Their Origins in the Modern Internet
Master of Science (MS), Ohio University, 2002, Computer Science (Engineering)

With the tremendous growth of Internet resources, we observe a rapid increase in the number of network applications and protocol implementations, which are not always thoroughly evaluated and tested. A growing number of network attacks attempt to disrupt legitimate communication or deny access to network resources to legitimate users. Both poor implementations and intentional abuse of network resources “pollute” a network with malformed packets and can become a threat to sound communication. In this work, we collect and analyze all of the IP and TCP headers of packets seen on a network that either violate existing standards or should not appear in modern internets. Our goal is to determine the reason that these packets appear on the network and evaluate what proportion of such packets could cause actual damage. Thus, we examine and divide the unusual packets obtained during our experiments into several categories based on their possible cause, which ranges from errors in network implementations to carefully constructed attack packets, and show the results. The traces analyzed were gathered at two different data sources at Ohio University’the university’s main Internet link connecting it to its ISP and a local network with student dormitory traffic – and provide a massive amount of statistical data.

Committee:

Shawn Ostermann (Advisor)

Subjects:

Computer Science

Keywords:

malformed packets; TCP/IP; traffic analysis; intrusion detection; packet header

Jero, Samuel C.Performance Analysis of the Datagram Congestion Control Protocol DCCP for Real-Time Streaming Media Applications
Master of Science (MS), Ohio University, 2013, Computer Science (Engineering and Technology)
The growth of real-time, streaming media application traffic in the Internet presents a number of challenges because the real-time constraints and interactive nature of these applications render the use of TCP ineffective. These streaming media application flows are usually high bandwidth and long duration, which means they should utilize network congestion control to avoid congestion collapse and ensure fairness. The Internet Engineering Task Force (IETF) developed the Datagram Congestion Control Protocol (DCCP) to provide congestion control for these types of real-time applications. A major factor behind this effort was the desire to eliminate the duplication of effort and potential for error resulting from each application implementing its own congestion control. In this research, we examine the difference in network performance and video quality for a typical application, a high bandwidth video telephony client, when using DCCP instead of the default transport protocol. We discuss several challenges to porting an application to DCCP and then examine the impact of DCCP on network and application performance in both testbed and Internet environments. We show that DCCP responds to changing network conditions within a few round trip times and provides better fairness to other network traffic than typical real-time, streaming media congestion control methods. Given fair bandwidth allocation, DCCP provides equivalent or better video quality, as measured by Peak Signal to Noise Ratio (PSNR) and Structural Similarity (SSIM).

Committee:

Shawn Ostermann (Advisor)

Subjects:

Computer Science

Keywords:

DCCP; Datagram Congestion Control Protocol; TFRC; TCP-Friendly Rate Control; network congestion; RTP; Real-Time Transport Protocol; network performance analysis; real-time streaming media; streaming media; streaming video

Swaro, James E.A Heuristic-Based Approach to Real-Time TCP State and Retransmission Analysis
Master of Science (MS), Ohio University, 2015, Computer Science (Engineering and Technology)
This study focuses on understanding how to classify out-of-order network traffic sent using the Transport Control Protocol(TCP). Packets that arrive out of order are the result of network reordering or loss recovery. TCP initiates loss recovery in response to the perceived loss of data, decreasing the congestion window and throughput of the connection. When TCP reacts poorly to loss, throughput may drop, latency may increase, and congestion collapse may occur. This thesis analyzes TCP traffic from an arbitrary observation point in a network, rather than at the TCP endpoint. Observing traffic at a TCP endpoint inhibits the inference of loss and detection of network reordering in one direction of the connection. Alternatively, observing traffic at an arbitrary point between two TCP endpoints allows inference of loss and detection of network reordering in both directions. Positioning the observation point at an arbitrary point can increase the diversity of observed connections, increasing the likelihood of detecting rare forms of aberrant behavior. In this paper, several algorithms and heuristics for classification of out-of-order TCP traffic are analyzed and implemented in a new TCP traffic analyzer called tcprs. An in-depth analysis of each algorithm and heuristic is given and compared with the results from tcptrace and tcpcsm. It was found that tcprs achieves an improvement in classification accuracy as compared with tcptrace and tcpcsm.

Committee:

Shawn Ostermann, Ph.D. (Advisor); David Juedes, Ph.D. (Committee Member); Jeffery Dill, Ph.D. (Committee Member); Hans Kruse, Ph.D. (Committee Member)

Subjects:

Computer Science

Keywords:

TCP; bulk trace analysis; traffic analysis; tcprs; retransmission analysis; network reordering analysis; congestion state detection; fine-grained retransmission detection

Yan, PengControl methods for data flow in communication networks
Doctor of Philosophy, The Ohio State University, 2003, Electrical Engineering
In this dissertation, we investigate various control methods for data flow in communication networks. First, we develop a rate-based flow controller for self-similar network traffic, which consists of a robust H-infinity control block and an adaptive LMMSE capacity predictor. The controller guarantees robust stability against time-varying time delay uncertainties and improves the transient response by predicting the self-similar cross traffic. Window-based congestion control methods are also explored for TCP traffic on IP networks. We propose a variable structure approach in Active Queue Management (AQM) support Explicit Congestion Notification (ECN). By analyzing the robustness and performance of the control scheme for the nonlinear TCP/AQM model, we show that the proposed design has good performance and robustness with respect to the uncertainties of the round-trip time (RTT) and the number of active TCP sessions, which are central to the notion of AQM. Alternatively, we design robust H-infinity AQM controllers for the linearized TCP/AQM model, with the presence of uncertain time delays. The H-infinity performance is analyzed and a switching control scheme is introduced to improve the system performance. Motivated by the Linear Parameter Varying (LPV) nature of the linearized TCP/AQM model, a switching H-infinity control method is further investigated for LPV systems where we provide some stability conditions in terms of the dwell time and the average dwell time.

Committee:

Hitay Ozbay (Advisor)

Keywords:

Control; Communication Networks; TCP/IP

Wang, YangDistributed parallel processing in networks of workstations
Doctor of Philosophy (PhD), Ohio University, 1994, Electrical Engineering & Computer Science (Engineering and Technology)

The main objective of this research is to explore the computing power of a network of workstations for the distributed execution of computationally intensive programs and to evaluate the overall network performance for such applications. The dynamic scheduling mechanism developed for this purpose requires that an application program be represented as a collection of subprograms in a task graph format showing the subprograms' dependency. An application program, described in such a format, is scheduled for parallel execution in the network in accordance with the load status information of the workstations as follows. The independent subtasks in a particular level of the task graph are distributed among the idle or lightly loaded processors (slaves) in the network by the user workstation (master) for parallel execution. The partial results are then collected by the master to ensure the synchronization among the slaves. This is repeated until all the subprograms at the different levels of the task graph are executed concurrently, and the final result is accumulated in the master station.

The performance of the network for this distributed program execution is characterized by the system speedup, which is defined as the ratio of the sequential execution time in a single workstation to the parallel execution in the network. The theoretical speedup equation is derived by modeling the network and considering various performance degradation factors including scheduling time, network load and size, communication time, TCP/IP communication overhead, task execution and synchronization time. The sequential and parallel execution times and the performance degradation factors were measured during the implementation for various network and station loads. The measurement values and theoretical results have shown that the system performance is degraded mostly by the heavily loaded nodes, the TCP/IP overhead (0.2 s), and the network size.

Committee:

Mehmet Celenk (Advisor)

Keywords:

distributed parallel processing; dynamic scheduling mechanism; TCP/IP communication overhead; theoretical speedup equation

FRANCIS, SHINCEREMOTE ADMINISTRATION OF AN AUTONOMOUS GUIDED VEHICLE THROUGH WEB BASED WIRELESS INTERFACES
MS, University of Cincinnati, 2003, Engineering : Industrial Engineering
Motion control is one of the most critical factors in the design of autonomous vehicles such as mobile robots. Bearcat III is an autonomous vehicle designed by the student at the Center for Robotics Research at the University of Cincinnati. The data transfer between the motion controller and the computer on Bearcat III is via serial port interface. This method is inflexible, sluggish and dated. A new motion control solution that uses a Galil DMC-2130 motion controller with a Galil ICM 1900 as the interconnect board is proposed. The new motion control system uses a DC brush less servo motor with encoders for feedback control. The choice of amplifier depends up on the choice of the motor type. This forms a closed loop feedback control system. The communication between motion controller (DMC-2130) and the central computer is achieved using Ethernet technology. This facilitates the use of Internet communication protocols and wireless communication standards to control the robot remotely. The new motion control system thus helps to control the robot via Internet and without physically present near the robot. The systems will be tested on the new robot, Bearcat cub, built by the students of the Center for Robotics Research. The significance of this work is in the increased understanding of motion control system for robot control and the synergetic combination of autonomous control of a robot and Internet and wireless communication standards in the field of defense and medicine.

Committee:

Dr. Ernest Hall (Advisor)

Subjects:

Engineering, Industrial

Keywords:

robotics; mobile robots; TCP/IP; wireless networking

Chi, YangEffective Use of Network Coding in Multi-hop Wireless Networks
PhD, University of Cincinnati, 2013, Engineering and Applied Science: Computer Science and Engineering
Multi-hop network has been envisioned to be a key technology in the next generation wireless networks. It offers the most flexible characteristic of the networks, requires no centralized or very small control, and very little configuration, thereby enjoying the quick deployment property. Yet, it has been named as the "next generation" for so many times that its usefulness is being questioned. The difficulty mainly comes from the inferiority in the performance being poor enough to make such networks overshadowed by other type of networks, unless quick deployment is a requirement, or performance is not a major concern. In this dissertation, we investigate the performance issues in multi-hop wireless networks. Some new architectures of multi-hop wireless networks with network coding are thoroughly explored. We first revisit network coding briefly. Being the latest revolution in the wireless world, network coding has evolved into a more practical shape, and has matured to a level so as to be adopted. A general introduction of network coding (network information theory) is covered for better understanding of how this technology would change the computer networks, and why we pick this topic for our research. The first work this dissertation covers is Murco, an opportunistic framework that brings the benefits of both multi-radio multi-channel technology and network coding to the multi-hop wireless networks. This combination, though it seems natural, faces many challenges. We address them with a loose collaboration between network coding and multi-radio technology coordinated by our framework. Our framework requires few changes or compromises on either side, and the simulation results demonstrate enhanced throughput. Following this work, we get into a more complex problem. Coding-aware routing in multi-hop wireless networks is vital for network coding's possible boom. We address this problem with a heuristic routing metric ETOX and a hybrid routing protocol HyCare. ETOX combines coding opportunities with other factors to provide both link and path measurements. HyCare employs ETOX as the routing metric and functions in both link-state routing and revrese forwarding manner. A cross-layer implementation is examined to validate our design paradigm. Our routing metric, ETOX, is inspired by a long-existing network traffic characteristic, namely Network Locality. During our research, we found that most previous works in Network Locality were conducted many years ago, and this area has been overlooked in wireless networks. To fully understand our routing metric, and to provide a foundation to other works that take Network Locality in wireless networks as granted, we also examine Network Locality in both single-hop and multi-hop wireless networks. The last work we introduced in this dissertation is TCP-Forward, a new transport layer protocol that gives TCP-like congestion control protocols a new life in lossy networks, like multi-hop wireless networks, with the help from network coding. Instead of using the most common intra-session network coding, the Random Linear Network Coding, we introduce Fountain Codes into the transport layer to provide both reliability and decoding efficiency. Due to the very nature and complexity of both congestion control and Fountain Codes, such a protocol can be a practicability headache. Our protocol is no exception and exposes great complexity in design and implementation. Our current implementation and results, though preliminary, has already showed some benefits over previous works.

Committee:

Dharma Agrawal, D.Sc. (Committee Chair); Yizong Cheng, Ph.D. (Committee Member); Chia Han, Ph.D. (Committee Member); Yiming Hu, Ph.D. (Committee Member); John Schlipf, Ph.D. (Committee Member)

Subjects:

Computer Science

Keywords:

Multi-hop Wireless Network;Network Coding;Multi-Radio Multi- Channel Networks;Coding-Aware Routing;Network Locality;TCP

Brennan, StephenExploring Alternative Routes Using Multipath TCP
Master of Sciences, Case Western Reserve University, 2017, EECS - Computer and Information Sciences
Multipath TCP (MPTCP) is an extension to TCP which allows hosts to establish connections consisting of multiple TCP “subflows” that travel across different Internet paths. MPTCP it is based on the assumption that at least one communicating host is multi-homed. Meanwhile, the Internet contains considerable path diversity, and research has shown that routes chosen by the Internet’s routing infrastructure are not always the most efficient. Although mechanisms have been proposed which are designed to take advantage of detour routing, none can be applied to unmodified applications. In this thesis, we leverage MPTCP to allow unmodified applications on single-homed devices to use detour routes. We find that this mechanism is capable of significant bandwidth aggregation under appropriate network conditions.

Committee:

Michael Rabinovich (Advisor); Mark Allman (Committee Member); Vincenzo Liberatore (Committee Member)

Subjects:

Computer Science

Keywords:

mptcp; multipath tcp; detour routing; overlay networking; openvpn; netfilter; linux kernel; mptcp path manager

Elza, DetheBrowser evolution: Document access on the world wide web
Master of Science (MS), Ohio University, 1998, Electrical Engineering & Computer Science (Engineering and Technology)

Browser evolution: Document access on the world wide web

Committee:

Shawn Ostermann (Advisor)

Keywords:

Transmission Control Protocol and Internet Protocol; TCP/IP; Hypertext Transfer Protocol; LaTeX

Olaleye, Olufunke ISymbiotic Audio Communication on Interactive Transport
MS, Kent State University, 2007, College of Arts and Sciences / Department of Computer Science

Audio perception is highly susceptible to disturbance in temporal quality. In the event of congestion, audio datagrams suffer packet loss, delay and jitter. Compressed audio appears as one of the most delicate traffic-type to handle on the Internet. The recent advances in auditory perception promise opportunities where a perceptually clever adaptive audio system can respond to impending breakdown and support near flawless sound. However, the major problem is receiving fast feedback from the current Internet. Recently proposed TCP Interactive (iTCP) seems to offer some interesting opportunity to perceptual audio. This is an operational state equivalent to the conventional TCP except that applications can optionally subscribe and receive selected local end-point protocol events in real-time.

In this thesis, we implemented a novel symbiotic perceptual audio streaming mechanism, that receives fast feedback from iTCP about congestion and then responds appropriately. This mechanism combines the quantization technique to accurately represent the audio signals without distortion. The adaptive system reduces the encoding target bit rate when congestion is detected which invariably reduces the delay and jitter faced by audio traffic in the network during congestion. We have tested it over the Internet. In this thesis, we highlight the performance of this system and report on the dramatic improvements in time-bounded streaming audio we observed.

Committee:

Javed Khan (Advisor)

Keywords:

TCP; iTCP; VoIP; congestion; voice; speech; audio; delay; jitter; packet loss; streaming audio; perceptual; quantization; symbiotic; throttling; exponential backoff; event notifier;event notification; MP3; distortion

Blanton, Joshua T.A Study of Transmission Control Protocol Selective Acknowledgement State Lifetime Validity
Master of Science (MS), Ohio University, 2008, Computer Science (Engineering and Technology)

The currently defined behavior for a standards-compliant Transmission Control Protocol (TCP) selective acknowledgment (SACK) sender, upon a retransmission timeout (RTO), is to infer that all previously-received SACK information is invalid. As all SACK information is advisory, it may be discarded at any time by either endpoint; however, discarding SACK information may have a detrimental impact on the connection's ability to recover without unnecessary retransmissions.

In this thesis, we analyze traces from actual Internet traffic to determine the behavior of SACK TCP endpoints, to determine the frequency with which they renege. We show that an inference between retransmission timeouts and SACK reneges is not valid in the majority of instances, and propose a mechanism for detecting invalid SACK state. Such a mechanism would allow senders to maintain SACK information beyond an RTO, while still allowing a receiver to discard out-of-sequence data when necessary. Furthermore, we claim that using such a detection mechanism may improve the recovery of connections after a retransmission timeout.

Committee:

Shawn D. Ostermann, PhD (Advisor)

Subjects:

Computer Science

Keywords:

TCP; SACK renege

Wang, HaiboHydroxyapatite degradation and biocompatibility
Doctor of Philosophy, The Ohio State University, 2004, Materials Science and Engineering
Hydroxyapatite (HA) is widely used as a bioactive ceramics since it forms a chemical bonding to bone. The disadvantage of this material is its poor mechanical properties. HA can be degraded in body, which is the reason for its bioactivity, but too fast degradation rate could cause negative effects, such as macrophage present, particle generation, and even implant clinical failure. HA degradation rate will be greatly changed under many conditions: purity, HA form (i.e. bulk form, porous form, coating, or HA/polymer composites), microstructure, implant site, body conditions, etc. Although much work has been done in HA properties and application areas, the HA degradation behavior and mechanism under these different conditions are still not clear. In this research, three aspects of HA degradation have been studied: 1) Two very common impurities—Tri-Calcium Phosphate (TCP) and Calcium Oxide and their influences on HA degradation in vitro and in vivo, 2) influence of HA/polymer composite form on HA degradation, 3) HA material particle generation and related mechanism. From the in vitro and in vivo tests on bulk HA disks with various Ca/P ratios, HA degradation can clearly be found. The degradation level is different in different Ca/P ratio samples as well as in different test environments. In same test environment, non-stoichiometric HA samples have higher degradation rate than stoichiometric HA. HA/PMMA composite design successfully intensifies HA degradation both in vitro and in vivo. Grain boundary damage can be found on in vivo test samples, which has not been clearly seen on bulk HA degraded surface. HA particle generation is found in in vitro and in vivo HA/PMMA composite surface and in vivo bulk HA surface. Sintering temperature and time does affect HA grain size, and this affect HA degradation rate. Intergranular fracture is found in a several micron zone close to the Ca/P ratio 1.62 and 1.67 sample degraded surfaces. At Ca/P ratio greater than 1.667, after HA degradation in water, solution pH increases because of CaO presence.

Committee:

John Lannutti (Advisor)

Keywords:

HA; HYDROXYAPATITE; implant; bone; Grain; ceramics; TCP

Chen, XinPerformance analysis of persistent hypertext transfer protocol (HTTP) over satellite links
Master of Science (MS), Ohio University, 1997, Electrical Engineering & Computer Science (Engineering and Technology)
HTTP/1.0 uses one request/response per TCP connection. Due to the TCP connection overhead and the TCP congestion control, this scheme works inefficiently. Persistent HTTP (HTTP/1.1) improves the network performance by allowing multiple requests/responses per TCP connection. In order to reduce the total elapsed time, pipelining technique must be used in HTTP/1.1. This thesis investigated the performance of HTTP/1.0, HTTP/1.1 and HTTP/1.1 Pipeline in satellite links by analyzing the TCP traffic data between the client and the server. HTTP/1.1 Pipeline improves the HTTP performance significantly. The effort is particularly obvious if the web page contains many small size inline images. Current implementations of HTTP/1.1 disable the nagle algorithm, solving the Odd/Short-Final-Segment Problem at the cost of producing many unfilled segment which will lower the network performance. This thesis suggests that the client and server exchange more information so that the server can disable the nagle algorithm or close the connection after the final response, this will improve the HTTP performance further.

Committee:

Shawn Ostermann (Advisor)

Keywords:

HTTP; TCP; Odd/Short-Final-Segment Problem