<div>Cloud and parallel computing are fundamental components in the processing of large data sets. Deployments of distributed computers require network infrastructure that is fast, efficient, and secure. Software Defined Networking (SDN) separates the forwarding of network data by switches (data plane) from the setting and managing of network policies (control plane). While this separation provides flexibility for setting network policies affecting the establishment of network flows in the data plane, it provides little to no fault tolerance for failures, either benign or caused by corrupted/malicious applications. Such failures can cause network flows to be incorrectly routed through the network or stop such flows altogether. Without protection against faults, cloud network providers using SDN run the risk of inefficient allocation of network resources or even data loss. Furthermore, the asynchronous nature existing protocols for SDN does not provide a mechanism for consistency in network policy updates across multiple switches.</div><div>In addition, cloud and parallel applications require an efficient means for accessing local system data (input data sets, temporary storage locations, etc.). While in many cases it may be possible for a process to access this data by making calls directly to a file system (FS) kernel driver, this is not always possible (e.g. when using experimental distributed FSs where the needed libraries for accessing the FS only exist in user space).</div><div>This dissertation provides a design for fault tolerance of SDN and infrastructure for advancing the performance of user space FSs. It is divided into three main parts. The first part describes a fault tolerant, distributed SDN control plane framework. The second part expands upon the fault tolerant approach to SDN control plane by providing a practical means for dynamic control plane membership as well as providing a simple mechanism for controller authentication through threshold signatures. The third part describes an efficient framework for user space FS access.</div><div>This research makes three contributions. First, the design, specification, implementation, and evaluation of a method for fault tolerant SDN control plane that is inter-operable with existing control plane applications involving minimal instrumentation of the data plane runtime. Second, the design, specification, implementation and evaluation of a mechanism for dynamic SDN control plane membership that all ensure consistency of network policy updates and minimizes switch overhead through the use of distributed key generation and threshold signatures. Third, the design, specification, implementation, and evaluation of a user space FS access framework that is correct to the Portable Operating System Interface (POSIX) specification with significantly better performance over existing user space access methods, while requiring no implementation changes for application programmers.</div>

<div>Advances in virtualization technologies have revolutionized the design of the core of cellular networks. However, the adoption of microservice design patterns and migration of services from purpose-built hardware to virtualized hardware has adversely affected the delivery of latency-sensitive services.</div><div><br></div><div>In this dissertation, we make a case for cloud-native (microservice container packaged) network functions in the cellular core by proposing domain knowledge-driven, traffic-aware, orchestration frameworks to make network placement decisions. We begin by evaluating the suitability of virtualization technologies for the cellular core and demonstrating that container-driven deployments can significantly outperform other virtualization technologies such as Virtual Machines for control and data plane applications.</div><div><br></div><div>To support the deployment of latency-sensitive applications on virtualized hardware, we propose using Virtual Network Function (VNF) bundles (aggregates) to handle transactions. Specifically, we design Invenio to leverage a combination of network traces and domain knowledge to identify VNFs involved in processing a specific transaction, which are then collocated by a traffic-aware orchestrator. By ensuring that a user request is processed by a single aggregate of collocated VNFs, Invenio can significantly reduce end-to-end latencies and improve user experience.</div><div><br></div><div>Finally, to understand the challenges in using container-driven deployments in real-world applications, we develop and evaluate a novel caller-ID spoofing detection solution in Voice over LTE (VoLTE) calls. Our proposed solution, NASCENT, cross validates the caller-ID used during voice-call signaling with a previously authenticated caller-ID to detect caller-ID spoofing. Our evaluation with traditional and container-driven deployments shows that container-driven deployment can not only support complex cellular services but also outperform traditional deployments.</div><div><br></div>

<div> <div> <div> <p>With the prevalence of web and cloud-based services, there is an ever growing requirement on the underlying network infrastructure to ensure that business critical traffic is continually serviced with acceptable performance. Networks must meet their performance requirements under failures. The global scale of cloud provider networks and the rapid evolution of these networks imply that failures are the norm in production networks today. Unplanned downtime can cost billions of dollars, and cause catastrophic consequences. The thesis is motivated by these challenges and aims to provide a principled solution to certifying network performance under failures. Network performance certification is complicated, due to both the variety of ways a network can fail, and the rich ways a network can respond to failures. The key contributions of this thesis are: (i) a general framework for robustly certifying the worst-case performance of a network across a given set of uncertain scenarios. A key novelty is that the framework models flexible network response enabled by recent emerging trends such as Software-Defined Networking; (ii) a toolkit which automates the key steps needed in robust certification making it suitable for use by a network architect, and which enables experimentation on a wide range of robust certification of practical interest; (iii) Slice, a general framework which efficiently classifies failure scenarios based on whether network performance is acceptable for those scenarios, and which allows reasoning about performance requirements that must be met over a given percentage of scenarios. We also show applications of our frameworks in synthesizing designs that are guaranteed to meet a performance goal over all or a desired percentage of a given set of scenarios. The thesis focuses on wide-area networks, but the approaches apply to data-center networks as well.</p></div></div></div>

<div>Cognitive agent architectures embed social learning algorithms and normative frameworks for adopting others’ influenced goals. However, there exists inefficiency in providing continuous, situational decision-making to emerge social, altruistic norms. The thesis reconstructs social-ecological learning mechanisms to functionally and efficiently internalize situational cooperation. By orienting agents to be self-aware of their three-dimensional vectors, i.e., physical, emotional and intellectual in graphical representations, this thesis hypothesizes the parsimonious, action-predictive four emotions that not only link perceptions, action, and cognition by events but also the emotional continuity functional to social-ecological rationality of agents in continuum. Twelve Meridian system is employed to conceptualize the equalizing, complementary, heuristic orientation (ECHO) model. ECHO simulates “naturalistic” cooperation to model embodied, social-ecological orientations by self-organizing emotions to emerge functional social network formations. ECHO delineates the soma links to perceptions, namely Twelve Meridian channels as “direct pipes” that initiates and conduct emotions and consciousness of three dimensional agenthood: physical, emotional, and intellectual desires. ECHO reconstructs emotions as entities to induce systemic, self-organized rule of delegation by integrating agents’ percepts and actuations. By modeling constitutional emotions and consciousness of eight entities, emotions within entities as “individualized emotional processors,” are constructing and integrating purposeful social, altruistic events for the efficacy of situated agents.<br></div>

Mobile ad hoc networks (MANETs), due to their unique characteristics (e.g., unsecured wireless channel, dynamic mobility, absence of central supportive infrastructure and limited resources), are suffering from a wide range of security threats and attacks. Particularly, MANETs are susceptible to the Denial of Service (DoS) attack that aims to disrupt the network by consuming its resources. In MANETs, a special form of DoS attack has emerged recently as a potentially major threat: the flooding attack. This attack recruits multiple attack nodes to flood the MANET with overwhelming broadcast traffic. This flooding traffic is so large that all, or most of, MANET resources are exhausted. As a result, the MANET is not able to provide any services. This thesis aims to investigate the flooding attack and propose detective security measures to defend MANETs against such an attack.

<div> <div> <div> <p>Billions of “smart” things in our lives have been equipped with various sensors. Current devices, such as smartphones, smartwatches, tablets, and VR/AR headsets, are equipped with a variety of embedded sensors, e.g. accelerometer, gyroscope, magnetometer, camera, GPS sensor, etc. Based on these sensor data, many technologies have been developed to track human motion at different granularities and to enable new applications. This dissertation examines two challenging problems in human motion tracking. One problem is the ID association issue when utilizing external sensors to simultaneously track multiple people. Although an “outside” system can track all human movements in a designated area, it needs to digitally associate each tracking trajectory to the corresponding person, or say the smart device carried by that person, to provide customized service based on the tracking results. Another problem is the inaccuracy caused by limited sensing information when merely using the embedded sensors located on the devices being tracked. Since sensor data may contain inevitable noises and there is no external beacon used as a reference point for calibration, it is hard to accurately track human motion only with internal sensors.</p><p>In this dissertation, we focus on applying multimodal sensing to perform human motion tracking in mobile systems. To address the two above problems separately, we conduct the following research works. (1) The first work seeks to enable public cameras to send personalized messages to people without knowing their phone addresses. We build a system which utilizes the users’ motion patterns captured by the cameras as their communication addresses, and depends on their smartphones to locally compare the sensor data with the addresses and to accept the correct messages. To protect user privacy, the system requires no data from the users and transforms the motion patterns into low-dimensional codes to prevent motion leaks. (2) To enhance distinguishability and scalability of the camera-to-human communication system, we introduce context features which include both motion patterns and ambience features (e.g. magnetic field, Wi-Fi fingerprint, etc.) to identify people. The enhanced system achieves higher association accuracy and is demonstrated to work with dense people in a retailer, with a fixed-length packet overhead. The first two works explore the potential of widely deployed surveillance cameras and provide a generic underlay to various practical applications, such as automatic audio guide, indoor localization, and sending safety alerts. (3) We close this dissertation with a fine-grained motion tracking system which aims to track the positions of two hand-held motion controllers in a mobile VR system. To achieve high tracking accuracy without external sensors, we introduce new types of information, e.g. ultrasonic ranging among the headset and the controllers, and a kinematic arm model. Effectively fusing this additional information with inertial sensing generates accurate controller positions in real time. Compared with commodity mobile VR controllers which only support rotational tracking, our system provides an interactive VR experience by letting the user actually move the controllers’ positions in a VR scene. To summarize, this dissertation shows that multimodal sensing can further explore the potential power in sensor data and can take sensor-based applications to the next generation of innovation.</p><div><br></div></div></div></div><div><div><div> </div> </div> </div>

<div>This thesis firstly surveys and summarizes the state-of-the-art studies from two research areas in Software Defined Networking (SDN) architecture: (i) control plane scalability and (ii) Quality of Service (QoS)-related problems. It also outlines the potential challenges and open problems that need to be addressed further for more scalable SDN control planes and better and complete QoS abilities in SDN networks. The thesis secondly presents a hierarchical SDN design along with an inter-AS QoS-guaranteed routing approach. This design addresses the scalability problems of control plane and privacy concerns of inter-AS QoS routing philosophies in SDN. After exploring the roots of control plane scalability problems in SDN, the thesis then proposes a metric to quantitatively evaluate the control plane scalability in SDN. Later, the thesis presents a general framework for economic analysis of network architectures and designs. To this end, the thesis defines and utilizes two metrics, Unit Service Cost Scalability and Cost-to-Service, to evaluate how SDN architecture performs compared to MPLS architecture in terms of unit cost for a service and cost of introducing a new service along with giving mathematical models to calculate Capital Expenditures (CAPEX) and Operational Expenditures (OPEX) of a network. Moreover, the thesis studies the problem of optimal final pricing for services by proposing an optimal pricing scheme for a service request with QoS in SDN environment while aiming to maximize benefits of both service providers and customers. Finally, the thesis investigates how programmable network architectures, i.e. SDN, affect the network economics compared to traditional network architectures, i.e. MPLS, in case of failures along with exploring the economic impact of failures in different SDN control plane models. </div>

The growth of interactive multimedia (IMM) applications is one of the major driving forces behind the swift evolution of next-generation wireless networks where the traffic is expected to be varying and widely diversified. The amalgamation of multimedia applications on high-speed wireless networks is somewhat a natural evolution. Wireless local area network (WLAN) was initially developed to carry non-real time data. Since this type of traffic is bursty in nature, the channel access schemes were based on contention. However real time traffic (e.g. voice, video and other IMM applications) are different from this traditional data traffic as they have stringent constraints on quality of service (QoS) metrics like delay, jitter and throughput. Employing contention free channel access schemes that are implemented on the point coordination function (PCF), as opposed to the numerous works on the contending access schemes, is the plausible and intuitive approach to accommodate these innate requirements. Published researches show that works have been done on improving the distributed coordination function (DCF) to handle IMM traffic. Since the WLAN traffic today is a mix of both, it is only natural to utilize both, DCF and PCF, in a balanced manner to leverage the inherent strengths of each of them. We saw a scope in this technique and develop a scheme that combines both contention and non-contention based phases to handle heterogeneous traffic in WLAN. Standard access scheme, like 802.11e, improves DCF functionality by trying to emulate the functions of PCF. Researchers have made a multitude of improvements on 802.11e to reduce the costs of implementing the scheme on WLAN. We explore improving the PCF, instead, as this is more stable and implementations would be less costly. The initial part of this research investigates the effectiveness of the point coordination function (PCF) for carrying interactive multimedia traffic in WLAN. The performance statistics of IMM traffic were gathered and analyzed. Our results showed that PCF-based setup for IMM traffic is most suitable for high load scenarios. We confirmed that there is a scope in improving IMM transmissions on WLAN by using the PCF. This is supported by published researches on PCF related schemes in carrying IMM traffic on WLAN. Further investigations, via simulations, revealed that partitioning the superframe (SF) duration according to the need of the IMM traffic has considerable impact on the QoS of the WLAN. A theoretical model has been developed to model the two phases, i.e., PCF and DCF, of WLAN medium access control (MAC). With this model an optimum value of the contention free period (CFP) was calculated to meet the QoS requirement of IMM traffic being transmitted. Treating IMM traffic as data traffic or equating both IMM and non-IMM together could compromise a fair treatment that should be given to these QoS sensitive traffic. A self-adaptive scheme, called MAC with Dynamic Superframe Selection (MDSS) scheme, generates an optimum SF configuration according to the QoS requirements of traversing IMM traffic. That particular scheme is shown to provide a more efficient transmission on WLAN. MDSS maximizes the utilization of CFP while providing fairness to contention period (CP). The performance of MDSS is compared to that of 802.11e, which is taken as the benchmark for comparison. Jitter and delay result for MDSS is relatively lower while throughput is higher. This confirms that MDSS is capable of making significant improvement to the standard access scheme.

<p>The accessibility and flexibility of mobile devices make them an advantageous platform for gaming, but there are hardware limitations that impede the rendering of high-quality graphics. Rendering complex graphics on a mobile device typically results in a delayed image, also known as latency, and is a great discomfort for users of any real-time rendering experience. This study tests the image stream optimization View Bypass within a cloud gaming architecture, surpassing this imposing limitation by processing the high-quality game render on a remote computational server. A two sample for means test is performed to determine significance between two treatments: the control group without the View Bypass algorithm and the experimental group rendering with the View Bypass algorithm. A SSIM index score is calculated comparing the disparity between the remote server image output and the final mobile device image output after optimizations have been performed. This score indicates the overall image structural integrity difference between the two treatments and determines the quality and effectiveness of the tested algorithm.</p>

Cognitive Radio technologies have been touted to be instrumental in solving resource-allocation problems in resource-constrained radio environments. The adaptive computational intelligence of these radios facilitates the dynamic allocation of network resources--particularly, the spectrum, a scarce physical asset. In addition to consumer-driven innovation that is governing the wireless communication ecosystem, its associated infrastructure is being increasingly viewed by governments around the world as critical national security interests--the US Military instituted the DARPA Spectrum Collaboration Challenge which requires competitors to design intelligent radios that leverage optimization, A.I., and game-theoretic strategies in order to efficiently access the RF spectrum in an environment wherein every other competitor is vying for the same limited resources. In this work, we detail the design of our radio, i.e., the design choices made in each layer of the network protocol stack, strategies rigorously derived from convex optimization, the collaboration API, and heuristics tailor-made to tackle the unique scenarios emulated in this DARPA Grand Challenge. We present performance evaluations of key components of our radio in a variety of military and disaster-relief deployment scenarios that mimic similar real-world situations. Furthermore, specifically focusing on channel access in the MAC, we formulate the spectrum sensing and access problem as a POMDP; derive an optimal policy using approximate value iteration methods; prove that our strategy outperforms the state-of-the-art, and facilitates means to control the trade-off between secondary network throughput and incumbent interference; and evaluate this policy on an ad-hoc distributed wireless platform constituting ESP32 radios, in order to study its implementation feasibility.