Doctor of Philosophy, The Ohio State University, 2019, Computer Science and Engineering

The explosive growth of the Internet, the advent of novel distributed applications, and an abundance of inexpensive hardware, have led to significant increases in the use of wireless networks. At present, different types of wireless networks are being used to support the requirements of several applications. WiFi networks are most widely used for universal access of the Internet. Vehicular networks that enable car-to-car communication have gained much attention because they can be utilized to develop a multitude of distributed applications to improve road safety and driving experience. Similarly, a dense deployment of inexpensive and battery-free (passive) radio frequency identification (RFID) tags is ideal for object tracking and monitoring in shopping malls and warehouses. Any wireless networks have to provide better performance when the number of users and applications increases rapidly. To meet this ever-increasing demand, we have proposed several protocols that utilize previously unused resources to gain additional information. Such information is beneficial for the design of collision-embracing protocols that allow simultaneous transmissions from multiple nodes for better resource utilization, resulting in improved performance. In our first work, a medium access control (MAC) protocol for WiFi networks, named BASIC, is devised. BASIC utilizes the high bandwidth Ethernet backbone networks that connect WiFi access points (APs). Multiple APs received packets from the same WiFi client, and several APs share this received signal among each other to maximize throughput from iia client. By working together, APs in enterprise WiFi networks can decode packets from several clients simultaneously, resulting in a considerable increment in the total throughput. As a continuation, a collision-embracing protocol, called CoReCast, is designed for vehicular networks and is suitable for broadcasting. CoReCast exploits the abundant power and the availabili (open full item for complete abstract)

Committee: Prasun Sinha (Advisor); Rajiv Ramnath (Committee Member); Can Koksal (Committee Member); Brent Sohngen (Committee Member) Subjects: Computer Engineering; Computer Science

PhD, University of Cincinnati, 2017, Engineering and Applied Science: Computer Science and Engineering

A ubiquitous pervasive network incorporates today's Internet of Things/Internet of Everything Paradigm: Everything becomes smart with at least one microprocessor and a network interface. All these are under an umbrella of IoT/IoE paradigm where everything is network capable and connected. In most of the cases, these devices have multiple microprocessors and network interfaces at their disposal. In such a scenario, bringing every application to specific network on the same platform is critical, specifically for Sensor Networks, Cloud, WPANs and VANETs. While, enforcing and satisfying the requirements of CIA triad with non-repudiation universally is critical as this can solve multiple existing problems of ISM band exhaustion, leading to excessive collisions and contentions. Cooperative Interoperability also enables universal availability of data across all platforms which can be reliable and fully synchronized. Plug and play universal usability can be delivered. Such a network necessitates robust security and privacy protocols, spanning uniformly across all platforms. Once, reliable data access is made available, it leads to an accurate situation aware decision modeling. Simultaneous multiple channel usage can be exploited to maximize bandwidth otherwise unused. Optimizing Content delivery in hybrid mode which will be the major chunk of network traffic as predicted for near future of IoE. Now, such a proposed hybrid network does sound very complicated and hard to establish and maintain. However, this is the future of networks with huge leaps of technological advancement and ever dropping prices of hardware coupled with immensely improved capabilities, such a hybrid ubiquitous network can be designed and deployed in a realistic scenario. In this work, we go through not only looking into the issues of the large scale hybrid WMN, but also minutely discovering every possible scenario of direct mesh clients or sub-nets (VANET, Cloud or BAN) associated to it. Further, we pr (open full item for complete abstract)

Committee: Dharma Agrawal D.Sc. (Committee Chair); Richard Beck Ph.D. (Committee Member); Yizong Cheng Ph.D. (Committee Member); Rashmi Jha Ph.D. (Committee Member); Wen-Ben Jone Ph.D. (Committee Member); Marepalli Rao Ph.D. (Committee Member) Subjects: Computer Science

PhD, University of Cincinnati, 2013, Engineering and Applied Science: Computer Science and Engineering

Vehicular networking is a new emerging wireless technology that supports the communication amongst vehicles and enables vehicles to connect with the Internet. This networking technology provides vehicles with endless possibility of applications, including safety, convenience, and entertainment applications. Examples for these applications are safety messaging, real-time traffic, route updates, and general purpose Internet access. The goal of vehicular networks is to provide an efficient, safe, and convenient environment for the vehicles. In vehicular networking technology, vehicles connect either through other vehicles in an ad-hoc multi-hop fashion or through road side units (infrastructure) which connects them to the Internet. Each approach has its own advantages and disadvantages. However, one of the main objectives of vehicular networking is to achieve a minimal delay for message delivery, and encourage a continuous connectivity for vehicles. This dissertation introduces a novel hybrid communication paradigm for achieving seamless connectivity in Vehicular Ad-hoc NETworks (VANET), wherein the connectivity is often affected by changes in the dynamic topology, vehicles' speed, as well as traffic density. Our proposed technique ---named QoS-oriented Hybrid Vehicular Communications Protocol (QoSHVCP)--- exploits both existing network infrastructure through a Vehicle-to-Infrastructure (V2I) protocol, as well as a traditional Vehicle-to-Vehicle (V2V), that satisfies Quality-of-Service requirements. We analyze time delay as a performance metric, and determine delay propagation rates when vehicles are transmitting high priority messages via QoSHVCP. Focusing on V2V communication, we propose a novel reliable and low-collision packet-forwarding scheme, based on a probabilistic rebroadcasting. Our proposed scheme, called Collision-Aware REliable FORwarding (CAREFOR), works in a distributed fashion where each vehicle receiving a packet, rebroadcasts it (open full item for complete abstract)

Committee: Dharma Agrawal D.Sc. (Committee Chair); Raj Bhatnagar Ph.D. (Committee Member); Yizong Cheng Ph.D. (Committee Member); John Franco Ph.D. (Committee Member); Chia Han Ph.D. (Committee Member); Yiming Hu Ph.D. (Committee Member) Subjects: Computer Science

Master of Science, Miami University, 2022, Computational Science and Engineering

Vehicular communication networks hold promise to significantly improve road safety by giving vehicles improved awareness and advanced warning to emergencies. By their urgent nature, VANET applications regarding safety typically have strict performance requirements on delay and medium congestion. This has led to many different proposed approaches to improving the performance of safety message dissemination. Though these proposed solutions are able to improve the performance, they frequently make no mention of whether or not the improved performance is yet sufficient for the application. The proposed research will develop a scheme for modulating the transmission range of safety message broadcasts in order to satisfy the directly-measured delay requirements of each vehicle in the network. This method would guarantee that the message is delivered to each vehicle in due time whilst minimizing the interference in the network. The proposed research expands upon existing preliminary work by integrating more complete analysis of transmission delay and interference and implementing a more general system model. The theoretical analysis validates the proposed strategy, and simulations further characterize the behavior of the strategy under different conditions. Using the proposed strategy, vehicles on the road can adjust their communications to guarantee safety to every vehicle without overloading the network.

Committee: Miao Wang (Advisor); Ran Zhang (Advisor); Gokhan Sahin (Committee Member) Subjects: Electrical Engineering

Doctor of Philosophy, The Ohio State University, 2022, Electrical and Computer Engineering

Wireless technologies have become a vital part of our daily lives over the past few decades. Today, the cellular communication technologies are used by billions of people, and many types of devices rely on the wireless technologies, such as Wi-Fi, Bluetooth. The ubiquitous deployment of wireless networks and devices has us surrounded by the wireless signals emitted from them. This motivates researchers to exploit these signals for different indoor and outdoor wireless sensing applications. In this dissertation, we aim to take advantage of the wireless signals sent in a vehicular ad hoc network (VANET) that enables the communication between vehicles and infrastructure units over an ad hoc network. Given the tremendous effort by the government agencies and the industry into realizing the vehicular networks on a large scale, we believe there are many opportunities for different applications relying on the vehicular communication besides the safety-related VANET applications. In this dissertation, we use the communication signals in a vehicular network to make situational inference on the road traffic conditions and the user authentication in the case of Sybil attacks. First, we focus on the road state inference using the wireless signals. Although a wide variety of sensor technologies are recently being adopted for traffic monitoring applications, most of these technologies rely on wired infrastructure. The installation and maintenance costs limit the deployment of the traffic monitoring systems. In this dissertation, we introduce a novel traffic inference approach that exploits physical layer samples in vehicular communications processed by machine learning techniques. We verify the feasibility of the proposed approach with extensive simulations and real-world experiments. We first simulate wireless channels under realistic traffic conditions using a ray-tracing simulator and a traffic simulator. Next, we conduct experiments in a real-world environment and collect (open full item for complete abstract)

Committee: Can Emre Koksal (Advisor); Ness Shroff (Committee Member); Eylem Ekici (Committee Member) Subjects: Computer Engineering; Computer Science; Electrical Engineering; Engineering

Doctor of Philosophy, The Ohio State University, 2017, Electrical and Computer Engineering

Vehicular Adhoc Networks (VANETs) promises to empower the future autonomous vehicles with a cooperative awareness facility that will help in avoiding accidents and alleviating traffic congestion. The foreseen collective awareness requires the vehicles to communicate with their neighbors and with the infrastructure; such communication will need the fulfillment of many requirements such as security, privacy, and efficiency. The Dedicated Short-Range Communication (DSRC) standard has been formulated to afford these requisites. On one hand, when focusing on the application layer, DSRC adopts the successful Internet-based Public Key Infrastructure (PKI) framework to safeguard the vehicles. However, PKI alone cannot comprehensively meet all of the security and privacy requirements. On the other hand, the DSRC 's Medium Access Control (MAC) layer adopts the IEEE 802.11p access mode, which also needs augmentation to fulfill the efficiency of communication when collisions arise for safety beacons. Since many issues have not been well addressed in DSRC, academic, industrial, and governmental research has flourished over the last two decades to complement the standard. As being part of such large research community, we also have been incentivized to contribute with our own solutions. Our contributions have been ranging between two limits: either finding solutions to acclimate with the available DSRC shortcomings or disregarding the bias that DSRC has towards using only specific standards by bringing other alternative frameworks into scene. With the first direction in mind, our efforts are a mixture of high-level re-arrangement protocols such as grouping and overhead omissions to minimize the PKI and Carrier Sense Multiple Access - Collision Avoidance (CSMA/CA) privacy and efficiency shortcomings. For the other direction, we especially address the application layer level. Since some frameworks have small communication overhead while others have high anonymous traits, we have at (open full item for complete abstract)

Committee: Fusun Ozguner Professor (Advisor); Can Emre Koksal Professor (Committee Member); Xiaorui Wang Professor (Committee Member) Subjects: Computer Engineering; Computer Science; Electrical Engineering; Transportation

Doctor of Philosophy, The Ohio State University, 2017, Computer Science and Engineering

Mobile devices such as smartphones are ubiquitous in society. According to Cisco Systems, there were eight billion mobile devices worldwide in 2016, which surpassed the human population. Mobile devices and wireless network infrastructure form an "electronic world" of signals that is part of daily life. However, navigating this world with users' devices is challenging. The volume of signals may confuse users, wireless communications often require manual connection establishment, and latency may be large (such as Bluetooth device discovery). Pervasive mobile device communications offer large-scale measurement opportunities when many devices connect to wireless networks. For example, base stations to which devices connect can indicate human mobility patterns. But existing work only studies coarse-grained cellular call records and datasets used in wireless local area network (WLAN) studies typically consist of laptops. Besides, existing vehicular communications technologies tend to be expensive and available for new vehicles only. This dissertation studies three topics that arise in the electronic world: unobtrusive communication among mobile devices without manual connection establishment; pervasive mobile device communications measurement; and cost-effective vehicular communication among mobile devices. First, we design Enclave that enables unobtrusive communication among mobile devices without network connections or configurations. Unobtrusive communication is efficient wireless communication that does not require user interruption such as manual device connection or network configuration. Enclave consists of a delegate mobile device (such as an unused phone) that interposes between a user's "master" device (such as her smartphone) and the electronic world. Enclave communicates between the master and delegate devices using wireless name communication and picture communication. Second, we study a new dataset with over 41 million anonymized (dis)association logs wit (open full item for complete abstract)

Committee: Dong Xuan Ph.D. (Advisor); Feng Qin Ph.D. (Committee Member); Ten-Hwang Lai Ph.D. (Committee Member) Subjects: Computer Science

Doctor of Philosophy, The Ohio State University, 2017, Electrical and Computer Engineering

Many studies show that the 5.9 GHz Dedicated Short Range Communication (DSRC) band with 75 MHz bandwidth is not sufficient to ensure reliable transmission of safety messages for the upcoming intelligent transportation systems. Moreover, the so-called vehicular spectrum scarcity problem is becoming severer in the DSRC band due to the rapid growth of wireless traffic demands in vehicular networks. Meanwhile, many frequency bands allocated to existing RF systems are largely underutilized. Since few new spectrum resources are available for vehicular communications, a potential solution to the spectrum scarcity problem in the DSRC band is to unload portion of the wireless traffic from the DSRC band to the other underutilized bands through spectrum sharing. The most fundamental requirement of the spectrum sharing approach is the protection of legacy users of the underutilized bands. In addition, a novel design of medium access control (MAC) protocols is required because few existing wireless MAC protocols support spectrum sharing functionality. This dissertation is focused on the resource allocation algorithm development and MAC protocol design to enable spectrum sharing between vehicular networks and other RF systems. Firstly, we study the sharing of the 54 MHz - 698 MHz TV White Space (TVWS) band between vehicular networks and licensed users of the band. The TVWS band has been officially released by FCC for cognitive access, and all existing wireless systems are allowed to access the band on condition that they must conform to FCC regulations on protection of legacy TVWS users. In this work, the channel allocation problem in the cognitive vehicular network is formulated as a nonlinear integer programming problem, to which three efficient approximation algorithms are developed. Secondly, we study the coexistence of vehicular networks and other unlicensed wireless networks in the TVWS band. The motivation of this study is that, multiple heterogeneous wireless networks (open full item for complete abstract)

Committee: Eylem Ekici (Advisor); Ness Shroff (Committee Member); Emre Koksal (Committee Member); Yuejie Chi (Committee Member) Subjects: Electrical Engineering

Doctor of Philosophy, The Ohio State University, 2014, Electrical and Computer Engineering

The rapid growth in wireless communication systems has provided a flexibility of communication and content that has had a transformative impact to all aspects of society. However, the broadcast nature of the wireless medium makes these systems vulnerable to passive attacks in which the adversary attempts to eavesdrop on the transmitted messages, and to active attacks in which the adversary can intelligently manipulate legitimate transmissions, both of which can jeopardize a myriad of critical wireless services. Hence, it is imperative to design wireless networks with safeguards in place to ensure their resilience to attacks. To that end, this dissertation provides various perspectives in the domain of information theoretic secrecy and authentication, which provably guarantees security, regardless of the computational capabilities of the adversary. We strive to bridge the gap between the information theory of security and the practically implementable protocols within this paradigm. We first consider point to point secure communication over flat fading wireless channels under delay constraint. We extend the definition of outage capacity to account for the secrecy constraint and obtain sharp characterizations of the corresponding fundamental limits under different assumptions on the transmitter channel state information (CSI). The capacity achieving scheme relies on opportunistically exchanging private keys between the legitimate nodes. These keys are stored in a key buffer and used to secure delay sensitive data. We also characterize the optimal power control policies and analyze the effect of key buffer overflow on the overall outage probability. Next, we focus on investigating additional sources for generating secret key bits in mobile wireless networks. We propose an algorithm for secret key generation based on the observations of the relative locations between a pair of nodes. We test our algorithm in a vehicular setting based on observations made (open full item for complete abstract)

Committee: Can Emre Koksal (Advisor); Hesham El Gamal (Advisor); Ness Shroff (Committee Member) Subjects: Electrical Engineering